Heat treatable, durable IR-reflecting sputter-coated glasses and method of making same

<u>FIELD OF INVENTION</u>

0001This invention relates to sputter-coated glasses and methods of making them. More particularly, this invention relates to sputter-coated glasses which are heat treatable and durable and whose solar management properties may be varied over a wide range so as to be useful for architectural, automotive and residential purposes.

<u>BACKGROUND OF THE INVENTION</u>

0002The popularity of metal and metal oxide coated glasses in architectural and automotive design is well known. As reported prolifically in patent and other literature, such glasses, usually achieve, through the manipulation of the coating's layering system, quite acceptable degrees of reflectance, transmittance, emissivity, chemical resistance, and durability, as well as the color desired. See, for example, in this respect, <patcit id="pcit0001" dnum="US3935351A"><text>U.S. Patent Nos. 3,935,351</text></patcit>; <patcit id="pcit0002" dnum="US4413877A"><text>4,413,877</text></patcit>; <patcit id="pcit0003" dnum="US4462883A"><text>4,462,883</text></patcit>; <patcit id="pcit0004" dnum="US3826728A"><text>3,826,728</text></patcit>; <patcit id="pcit0005" dnum="US3681042A"><text>3,681,042</text></patcit>; <patcit id="pcit0006" dnum="US3798146A"><text>3,798,146</text></patcit>; and <patcit id="pcit0007" dnum="US4594137A"><text>4,594,137</text></patcit> just to name a few.

0003It has also been well reported that while several reasonably acceptable techniques exist for applying such coatings, one of the most efficacious, and thus preferred, is the well known technique referred to as "magnetically enhanced sputter coating". Such a technique is reported in <patcit id="pcit0008" dnum="US4166018A"><text>U.S. Patent No. 4,166,018</text></patcit>, a recognized fundamental teaching on the subject. (See also, <nplcit id="ncit0001" npl-type="s"><text>Munz et al "Performance and Sputtering Criteria of Modern Architectural Glass Coatings", SPIE Vol. 325, Optical Thin Films, 1982, pp. 65-73</text></nplcit>.)

0004While efficacious for many known layer systems, the use of certain older sputter coating system has been known to result in mechanical durability qualities less than that achieved by another known method called the "pyrolytic" technique. As a reverse function, however, sputter-coated systems often achieve better infrared reflectance than typical pyrolytic coatings. Also, sputter-coated glasses have generally been recognized as having superior optical and thermal performance characteristics than pyrolytically formed coatings, such as having improved coating uniformity, good emittance, and better solar performance characteristics. It is clear, that if a sputter-coating technique could be devised for a particular coating system wherein the mechanical durability qualities of the sputter-coated system could approach or equal that of a pyrolytic technique, while at the same time achieving the enhanced benefits of sputter-coated technology, a significant step forward in the art would be made.

0005In <patcit id="pcit0009" dnum="US5229194A"><text>U.S. Patent No. 5,229,194</text></patcit>, entitled "Improved Heat Treatable Sputter-Coated Glass Systems" there are disclosed certain unique layer systems that achieved this significant step forward in the art. These systems are prior art to the subject invention due to commercial sale more than one year prior to our filing date herein. They are discussed more fully below.

0006Firstly, however, it should be stated that in recent years, the popularity of coated glasses has occasioned numerous attempts at achieving a coated glass article which, prior to heat treatment, can be coated, and which thereafter, can be heat treated without adversely changing the characteristics of the coating or the glass itself (i.e. the resulting glass article). One of the reasons for this is, for example, that it can be extremely difficult to achieve a uniform coating on an already bent piece of glass. It is well known that if a flat glass surface can be coated and thereafter bent, much simpler techniques can be used to get a uniform coating than if the glass has been previously bent. This is true, in this respect, for architectural and residential glass, but is particularly true for automotive glass such a bent glass windshields which in recent years have had to take on more aerodynamically efficient designs to aid in achieving increased fuel economy.

0007Certain techniques have been developed in the past for making coated heat treatable glass articles which may then, and thereafter, be heat treated by way of tempering, bending, or a technique known as "heat strengthening". Generally speaking, many of these prior coated articles have suffered from not being heat treatable at the higher, elevated temperatures necessary to achieve economic bending, tempering, and/or heat strengthening (i.e. 1150°F - 1450°F). In short, such techniques have often suffered from a need to keep the temperature at approximately 1100°F or less in order to achieve heat treatability without adversely affecting the coating or its substrate.

0008This latter situation; namely the absence of any substantial adverse affect upon the coating or its substrate, defines what is meant herein by the term "heat treatable". While in certain situations, some characteristics may change somewhat during heat treatment, to be "heat treatable" as used herein means that the desired properties of the ultimate layer system and overall product must be achieved despite the fact that the coated glass has been subjected to one or more of the heat treatments discussed above (i.e. bending, tempering and/or heat strengthening). For most architectural purposes contemplated by this invention optimized heat treatability means that the glass and its layered coating remains substantially unchanged in its visual (optical) appearance as between the pre-heat treated product and the final product after heat treatment. For most automotive purposes change for the better due to the heat treatment may be tolerated and is even desirable, so long as optimized heat treatability means that the change takes place uniformly across the substrate and is independent of the parameters used to perform the heat treatment.

0009In this respect, <patcit id="pcit0010" dnum="US5188887A"><text>U.S. Patent No. 5,188,887</text></patcit> discloses certain prior art coating systems which are heat treatable because they can be heat treated successfully at the higher, more elevated temperatures aforesaid, to achieve the desired result despite having gone through tempering, bending or heat strengthening. Generally speaking, these prior art coating compositions find their uniqueness in a layering system which employs as a metallic layer, a high nickel content alloy which, in its preferred form, is an alloy known as Haynes 214, consisting essentially of 75.45% Ni, 4.00% Fe, 16.00% Cr, 0.04% C, 4.50% Al, and 0.01% Y (percentages are by weight). By using a high nickel content alloy, such as Haynes 214, and overcoating it with stoichiometric tin oxide (SnO₂) either alone or with other layers (such as an undercoat of the same stoichiometric tin oxide and/or an intermediate layer of aluminum between the top SnO₂ layer and the high content nickel alloy), it was found that heat treatability of glass articles at elevated temperatures of from approximately 1150°F - 1450°F from about 2-30 minutes, could be achieved without substantial degradation of color, mechanical durability, emissivity, reflectance or transmittance. These compositions therefore constituted a significant improvement over prior heat treatable systems such as those disclosed in the following patents: <patcit id="pcit0011" dnum="US4790922A"><text>4,790,922</text></patcit>; <patcit id="pcit0012" dnum="US4816034A"><text>4,816,034</text></patcit>; <patcit id="pcit0013" dnum="US4826525A"><text>4,826,525</text></patcit>; <patcit id="pcit0014" dnum="US4715879A"><text>4,715,879</text></patcit>; and <patcit id="pcit0015" dnum="US4857094A"><text>4,857,094</text></patcit>.

0010In addition to the above disclosures in the aforesaid patents, the Leybold windshield glass system TCC-2000 is also known. In this system, four or five layers of metals and metal oxides are employed to obtain a sputter-coated glass which, being somewhat heat treatable at temperatures up to 1100°F may be used as a pre-coated glass for making bent or unbent, glass windshields, provided that rapid time limits are placed on the heat treatment. The layering from glass substrate outwardly usually includes a first layer of tin oxide, a second layer of nickel/chrome alloy (usually about 80/20), a third layer of silver, a fourth layer of the nickel/chrome alloy, and a fifth layer of tin oxide. In addition to the rather low upper limit on heat treatment temperature and times, the resultant coatings are rather soft and exhibit such unacceptably low chemical resistance characteristics that they can realistically be used only on the inner surfaces of laminated glass windshields.

0011In the aforesaid <patcit id="pcit0016" dnum="US4715879A"><text>U.S. Patent No. 4,715,879</text></patcit> it is specifically taught that the layering system therein cannot be achieved unless the protective layer of a metal oxide (e.g. tin oxide) be formed such that the oxide has an oxygen deficit (i.e. is non-stoichiometric). This, of course, requires delicate balancing in the manufacturing process. Heat treatability, in this respect, is also disclosed in <patcit id="pcit0017" dnum="US4826525A"><text>U.S. Patent No. 4,826,525</text></patcit>. However, in this patent it is specifically taught that a layer of aluminum must be applied to achieve heat treatability.

0012In the aforesaid <patcit id="pcit0018" dnum="US5229194A"><text>U.S. Patent No. 5,229,194</text></patcit>, a significant advance in heat treatable sputter coatings is disclosed, even when compared to those disclosed in <patcit id="pcit0019" dnum="US5188887A"><text>U.S. Patent No. 5,188,887</text></patcit>. In that invention it was found that unique results in the area of heat treatable sputter-coated glasses were achievable, particularly when used as "privacy" windows in vehicles, if metallic nickel or a high content metallic nickel alloy layer were surrounded by an undercoat and overcoat of a separate layer of an oxide or nitride of nickel or high content nickel alloy, and a further overcoat of an oxide such as SnO₂, ZnO, TiO₂ or oxide alloys thereof was employed. Silicon is also mentioned as useful for the first overcoat of the metallic nickel-containing layer.

0013Such layering systems in their preferred forms proved particularly heat treatable and abrasion resistant. However, while some were found initially to be chemically resistant, certain systems when put into mass production were found not to pass the rather rigorous 5% HCl boil chemical resistance test (discussed below). Their infrared and UV reflectance characteristics were, however, found to be excellent for a wide range of uses. Still further, however, their visible light transmittance values, desirably low for "privacy" window use, nevertheless proved to be too low to be truly useful as glass windows or panels for architectural or residential purposes where high visible light transmittance is required. Thus when production called for the sputter-coater to fulfill orders for architectural or residential coated glass after glass sheets for "privacy" windows had been coated, the coater had to be shut down so that a new layer system could be formed. If such a shutdown could be avoided a significant economic advance would be accomplished.

0014In our commonly owned, copending application Serial No. <patcit id="pcit0020" dnum="WO07876350A"><text>07/876,350</text></patcit> filed April 30, 1992, entitled "High Performance, Durable, Low-E Glass and Method of Making Same", there are disclosed certain unique sputter-coated layering systems having unique applicability for architectural and residential purposes because of their achievement of not only good chemical and mechanical durability, but their solar management properties as well. These systems are properly deemed "low-E" glasses (coatings) because their hemispherical emissivity (E_n) was generally less than about 0.16 and their normal emissivity (E_n) was generally less than about 0.12. Measured another way their sheet resistance was preferably less than about 10.50 ohms/square. In addition, for normal glass thicknesses (e.g. 2 mm-6 mm) visible light transmittance was preferably about 78% or more (compared to less than about 22-23% in certain preferred embodiments of the aforesaid heat treatable "privacy" window layer systems).

0015The invention in this aforesaid copending application Serial No. <patcit id="pcit0021" dnum="WO07876350A"><text>07/876,350</text></patcit>, now <patcit id="pcit0022" dnum="US5344718A"><text>U.S. Patent No. 5,344,718</text></patcit>, achieved its unique low-E, high visible light transmittance values, along with its good chemical durability and resistance to abrasion, by employing a layer system which generally comprised (from glass outwardly) an undercoat layer of Si₃N₄, a first layer of nickel or nickel alloy, a layer of silver, a second layer of nickel or nickel alloy, and an overcoat layer of Si₃N₄. In certain preferred embodiments, the layer system from glass outwardly consisted essentially of: Si₃N₄/Ni:Cr/Ag/Ni:Cr/Ag/Ni:Cr/Si₃N₄ This seven layer system was found to exhibit somewhat higher durability and scratch resistance characteristics than the above-described five layer system. In each system, however, the preferred Ni:Cr layer was nichrome, i.e. 80/20 by weight Ni/Cr, and in which a substantial portion of the chromium formed as a nitride of Cr because the Ni:Cr layer was formed in a nitrogen-containing atmosphere.

0016Unfortunately, these durable, low-E, high visible transmittance glass layer systems proved to be non-heat treatable. This has now been found to be true not because of any oxidation of the silver layer(s) but because the metallic silver layer(s) during heat treatment become(s) discontinuous due to non-wetting; in this case because the Ni:Cr surrounding layers are insufficient to maintain the continuity of the silver layer(s) during heat treatment. Thus these otherwise advantageous layer systems could not be used where the layered glass was thereafter to be heat treated as by tempering, heat strengthening and bending. Unfortunately the silver layers were necessary to employ in order to achieve the desired low-E levels.

0017It is to be remembered in this respect that it is not just in the automotive windshield art where heat treatable sputter-coated layer systems find their utility. Certain architectural and residential uses also require the coated glass to be tempered, bent, or heat strengthened. Still further, the low-E glass systems of the aforesaid invention in copending application Serial No. <patcit id="pcit0023" dnum="WO07876350A"><text>07/876,350</text></patcit>, now <patcit id="pcit0024" dnum="US5344718A"><text>U.S. Patent No. 5,344,718</text></patcit>, could generally not be adjusted to achieve low enough visible transmittance values to make them useful in "privacy" windows, even if they were heat treatable...which they were not. For these reasons then, these low-E glass systems did not overcome the aforesaid production problem of having to shut down the system to satisfy the needs of customers requiring widely varying solar management characteristics in their sputter-coated glass products.

0018Compounding the above-described problem was the problem created in the sputter-coating chamber by the need to create an Si₃N₄ layer or layers in the layering system of the aforesaid copending application Serial No. <patcit id="pcit0025" dnum="WO07876350A"><text>07/876,350</text></patcit>. In order to achieve such a layer, an Si target (usually doped with aluminum) as the cathode was employed. Sputter coating was then conducted in an N₂ containing atmcsphere to create Si₃N₄ by reaction. Unfortunately Si₃N₄ is a non-conductor (as is the small amount of aluminum nitride formed from the Al dopant which also coats the anode during sputter-coating). Coating efficiency deteriorates and shutdown times can be extensive.

0019In our copending application, Serial No. <patcit id="pcit0026" dnum="WO08102585A"><text>08/102,585</text></patcit>, now <patcit id="pcit0027" dnum="US5403458A"><text>US-A-5,403,458</text></patcit> filed simultaneously herewith and entitled "Sputter-Coating Target and Method of Use", a unique solution to this problem is disclosed. Generally speaking, the solution is to create a cathode target which has a prescribed amount of a conductive metal dispersed in the Si so that its nitride (or the metal if it does not form a nitride during the sputter-coating operation) forms on the anode in sufficient amounts to maintain conductivity for an enhanced period of time, thus avoiding numerous shutdowns. The entire disclosure of this copending application is incorporated herein by reference.

0020Heretofore if the skilled artisan wished to continue to achieve the known benefits of abrasion and corrosion resistance by using Si₃N₄ layers, but also wished to avoid costly downtime, while at the same time needing to achieve heat treatability and yet have flexibility to vary the solar management properties over a reasonably wide range to avoid further production shutdowns (to meet the needs of different customers), that artisan was faced with an unsolvable problem. In this respect, the mere choice of any conductive metal as the dispersant (i.e. dopant) in an Si target would not inherently solve the problem, for that metal, while overcoming the anode coating problem may well defeat heat treatability and/or the desired levels of durability, and/or solar management (including color) characteristics which must be achieved.

0021It is therefore, apparent that there exists a need in the art for a sputter-coated layer system which achieves the benefits of sputter-coating while overcoming the above-described problems and drawbacks in the art. It is a purpose of this invention to fulfill this need in the art as well as other needs which will become apparent to the skilled artisan once given the following disclosure.

SUMMARY OF THE INVENTION

0022Generally speaking this invention fulfills the above-described needs in the art by providing a glass article as claimed in claim 1. This invention further fulfills the above-described needs in the art by providing a method of heat treating a coated glass article as claimed in claim 14.

0023In certain preferred embodiments of this invention the layer system further includes an undercoat layer of Si₃N₄, and each of the Si₃N₄ layers includes a small amount of a dopant conductive metal or conductive metal nitride as a result of the use of such a metal as a dispersant (dopant) in the Si cathode target of the sputter coating apparatus to overcome the above-described problem of downtime due to coating of the anode with non-conductive Si₃N₄. The dopant, conductive metal is, of course, chosen so as to, at worst, have no adverse affect upon the solar management or other physical characteristics desired in the final product. In certain preferred systems, this dopant metal is selected from titanium, zirconium, hafnium and mixtures thereof.

0024The layer systems as aforesaid are preferably formed by sputter coating each layer to its requisite thickness onto a glass substrate. While the glass thickness may be varied widely, typically the glass article will be of the float glass type and have a thickness of about 1.5-13.0 mm (i.e. about 0.060"-0.50") and more usually about 2 mm-6 mm. The glass may be tinted or non-tinted, or patterned glass. Such glass may be of the single strength type. In certain further preferred forms of this invention, then, and when measured by application to a glass substrate having a conventional thickness of about 4.0 mm the resultant glass article, after being heat treated will have the following characteristics: <tables id="tabl0001" num="0001"><table frame="all"><tgroup cols="2"><colspec colnum="1" colname="col1" colwidth="50mm" /><colspec colnum="2" colname="col2" colwidth="40mm" /><thead valign="top"><row><entry align="center">Characteristic</entry><entry>Range</entry></row></thead><tbody><row><entry>Visible Transmission:</entry><entry>about 1% - 80%</entry></row><row><entry>Visible Reflectance (glass side):</entry><entry>about 4% - 55%</entry></row><row><entry>Visible Reflectance (film side):</entry><entry>about 4% - 65%</entry></row><row><entry>Visible Color (glass side):</entry><entry>silver, pewter, blue, gray</entry></row><row><entry>Emittance (normal, i.e. E_n):</entry><entry>about 0.10-0.60</entry></row><row><entry>Sheet Resistance (R_S):</entry><entry>about 2-250 ohms/square</entry></row><row><entry>Solar Transmission:</entry><entry>about 1% - 80%</entry></row></tbody></tgroup></table></tables> The above table shows how flexible the systems of this invention are to meet a wide range of solar management needs.

0025Transmission and Reflectance are recorded as Illuminant C, 2° observer. A more preferred range of Normal Emittance (E_n) is about 0.15-0.35 for many uses. A more preferred range of Sheet Resistance is about 15-35 ohms/square for many uses. In the most preferred forms of this invention the resultant article, and its layer system, both before and after heat treatment exhibits excellent chemical resistance and durability (i.e. abrasion or scratch resistance). "Chemical resistance" is determined by boiling a 2" x 5" sample of the article in about 500 cc of 5% HCl for one hour (i.e. about 220°F). The article is deemed to pass this test if it shows no pinholes greater than about 0.003" in diameter after this one hour boil. "Durability" is measured by two tests, first a conventional Taber abrader test using a 4" x 4" sample and one a 500 g.wt. attached to each of two C.S. 10F abrasion wheels rotated through 300 revolutions. Durability may further be tested using a Pacific Scientific Abrasion Tester (1" nylon brush cyclically passed over the coating in 500 cycles employing 150 gms. of weight, applied to a 6" x 17" sample). In both tests if no substantial, noticeable scratches appear when viewed with the naked eye under visible light, the test is deemed passed, and the article is said to be durable.

0026Transmission properties in the preferred forms of this invention are as indicated above when measured by the conventional Illuminant C, 2° observer test using a glass substrate of about 4 mm. To be "heat treatable" within the meaning of the preferred forms of this invention, transmission (visible and solar) should not be changed by heat treatment more than about 20% and preferably less than about 10%. Most preferably it changes less than about 2%. In addition, to be "heat treatable" within the meaning of the most preferred forms of this invention, sheet resistance (R_s) should not be increased more than about 10% during heat treatment. Preferably it is not increased at all, and most preferably it is decreased slightly by such heat treatment.

0027By way of further explanation of the above characteristics, the terms "emissivity" and "transmittance" are well understood in the art and are used herein according to their well known meaning. Thus, for example, the term "transmittance" herein means solar transmittance, which is made up of visible light transmittance, infrared energy transmittance, and ultraviolet light transmittance. Total solar energy transmittance is then usually characterized as a weighted average of these other values. With respect to these transmittances, visible transmittance, as reported herein, is characterized by the standard Illuminant C technique, 2° observer, at 380-720 nm; infrared is 800-2100 nm; ultraviolet is 300-400 nm; and total solar is 300-2100 nm. For purposes of emissivity, however, a particular infrared range (i.e. 2,500-40,000 nm) is employed, as discussed below.

0028Visible transmittance can be measured using known, conventional techniques. For example, by using a spectrophotometer, such as a Beckman 5240 (Beckman Sci. Inst. Corp.), a spectral curve of transmission at each wavelength is obtained. Visible transmission is then calculated using ASTM E-308 "Method for Computing the Colors of Objects by Using the CIE System" <i>(Annual Book of ASTM Standards,</i> Vol. 14.02). A lesser number of wavelength points may be employed than prescribed, if desired. Another technique for measuring visible transmittance is to employ a spectrometer such as a commercially available Spectragard spectrophotometer manufactured by Pacific Scientific Corporation. This device measures and reports visible transmittance directly.

0029"Emissivity" (E) is a measure, or characteristic of both absorption and reflectance of light at given wavelengths. It is usually represented by the formula:<maths id="math0001"><math display="block"><mi mathvariant="normal">E</mi><mo>=</mo><mn>1</mn><mo>-</mo><msub><mi>Reflectance</mi><mi>film</mi></msub></math><img file="EP0747329B2_D0001.tif" /></maths>

0030For architectural purposes, emissivity values become quite important in the so-called "mid range", sometimes also called the "far range", of the infrared spectrum, i.e. about 2,500-40,000 nm. The term "emissivity", as used herein, is thus used to refer to emissivity values measured in this infrared range as specified by the 1991 Proposed ASTM Standard for measuring infrared energy to calculate emittance, as proposed by the Primary Glass Manufacturers Council and entitled "Test Method for Measuring and Calculating Emittance of Architectural Flat Glass Products Using Radiometric Measurements". This Standard, and its provisions, are incorporated herein by reference. In this Standard, emissivity is broken into two components, hemispherical emissivity (E_h) and normal emissivity (E_n).

0031The actual accumulation of data for measurement of such emissivity values is conventional and may be done by using, for example, a Beckman Model 4260 spectrophotometer with "VW" attachment (Beckman Scientific Inst. Corp.). This spectrophotometer measures reflectance versus wavelength, and from this, emissivity is calculated using the aforesaid 1991 Proposed ASTM Standard which has been incorporated herein by reference.

0032Another term employed herein is "sheet resistance". Sheet resistance (R_s) is a well known term in the art and is used herein in accordance with its well known meaning. Generally speaking, this term refers to the resistance in ohms for any square of a layer system on a glass substrate to an electric current passed through the layer system. Sheet resistance is an indication of how well the layer is reflecting infrared energy, and is thus often used along with emissivity as a measure of this characteristic, so important in many architectural and automotive glasses. "Sheet resistance" is conveniently measured by using a 4-point probe ohmmeter, such as a dispensable 4-point resistivity probe with a Magnetron Instruments Corp. head, Model M-800 produced by Signatone Corp. of Santa Clara, California.

0033This invention will now be described with respect to certain embodiments thereof as discussed below and illustrated in the following drawings, wherein:

IN THE DRAWINGS

LEGEND

0034<dl id="dl0001" compact="compact"><dt>Si₃N₄ =</dt><dd>a layer comprised of at least about 90% silicon nitride</dd><dt>Ni =</dt><dd>metallic nickel</dd><dt>M =</dt><dd>a nickel containing metal layer substantially free of any nitride of that metal</dd><dt>M/O =</dt><dd>a layer wherein a very small amount of oxidation of the nickel containing metal layer has taken place, the layer remains substantially free of any nitride of the metal</dd><dt>MO_x =</dt><dd>the layer is stoichiometrically oxidized metal</dd><dt>glass =</dt><dd>the glass substrate (also "G" in <figref idref="f0002">Figure 7</figref>)</dd><dt>W₂ =</dt><dd>first washer</dd><dt>W₁ =</dt><dd>second washer</dd><dt>T =</dt><dd>tunnel</dd><dt>C =</dt><dd>conveyor</dd><dt>F =</dt><dd>chamber separator wall</dd></dl> and wherein; <figref idref="f0001">Figures 1-6</figref> are partial cross-sectional views wherein: <ul id="ul0001" list-style="none" compact="compact"><li><figref idref="f0001">Figure 1A</figref> illustrates a two layer system according to this invention;</li><li><figref idref="f0001">Figure 1B</figref> illustrates the layer system of <figref idref="f0001">Figure 1A</figref> with a silicon nitride undercoat;</li><li><figref idref="f0001">Figure 2A</figref> illustrates another two layer system according to this invention;</li><li><figref idref="f0001">Figure 2B</figref> illustrates the layer system of <figref idref="f0001">Figure 2A</figref> with a silicon nitride undercoat;</li><li><figref idref="f0001">Figure 3A</figref> illustrates a four layer system according to this invention;</li><li><figref idref="f0001">Figure 3B</figref> illustrates the layer system of <figref idref="f0001">Figure 3A</figref> with a silicon nitride undercoat;</li><li><figref idref="f0001">Figure 4A</figref> illustrates a five layer system according to this invention;</li><li><figref idref="f0001">Figure 4B</figref> illustrates the five layer system of <figref idref="f0001">Figure 4A</figref> wherein the metal "M" is partially oxidized;</li><li><figref idref="f0001">Figure 5A</figref> illustrates another two layer system according to this invention;</li><li><figref idref="f0001">Figure 5B</figref> illustrates the two layer system of <figref idref="f0001">Figure 5A</figref> with a silicon nitride undercoat;</li><li><figref idref="f0001">Figure 6</figref> illustrates a nine layer system according to this invention;</li><li><figref idref="f0002">Figure 7</figref> is a schematic illustration of a conventional Airco 5-chamber sputter coater useful in making the coated glass articles of this invention.</li></ul>

DETAILED DESCRIPTION OF CERTAIN EMBODIMENTS

0035As contemplated by this invention, the layer systems as illustrated (e.g. <figref idref="f0001">Figures 1A-6</figref>) are heat treatable within the meaning of that term as defined above. As further stated above, in their preferred forms, heat treatment actually may improve the article by increasing its IR reflectance (e.g. as indicated by a reduction in sheet resistance, R_s).

0036It has been found that to achieve this heat treatability, each layer should have a finite thickness which is generally continuous in nature. The thickness of any particular layer or the system as a whole may, so long as each layer is substantially continuous, be varied over a wide range depending upon the material used for the layer, the heat treatment to be used, the number of layers in the system, and the characteristics desired in the ultimate product. Generally speaking, however, the following ranges of thicknesses have been found to give the best results for most contemplated purposes: <tables id="tabl0002" num="0002"><table frame="all"><tgroup cols="2" rowsep="0"><colspec colnum="1" colname="col1" colwidth="37mm" /><colspec colnum="2" colname="col2" colwidth="25mm" /><thead valign="top"><row rowsep="1"><entry /><entry align="center">Thickness (Å)</entry></row></thead><tbody><row><entry>Si₃N₄ (overcoat)</entry><entry>10-750</entry></row><row><entry>M (nickel or nickel alloy)</entry><entry>50-300</entry></row><row><entry>MO_x</entry><entry>50-100</entry></row><row><entry>M/O</entry><entry>50-500</entry></row><row><entry>Ni/Si₃N₄</entry><entry>50-300</entry></row><row><entry>Si₃N₄ (intermediate)</entry><entry>500-1200</entry></row><row rowsep="1"><entry>Si₃N₄ (undercoat)</entry><entry>10-750</entry></row></tbody></tgroup></table></tables>

0037An important aspect of this invention is the use of silicon nitride (Si₃N₄) as a layer or layers in the system. In this respect various forms of silicon nitride containing materials were heretofore known for use as a coating material capable of providing resistance to abrasion and corrosion in a layer system. See, for example, <patcit id="pcit0028" dnum="US4769291A"><text>U.S. Patent Nos. 4,769,291</text></patcit>; <patcit id="pcit0029" dnum="US5062937A"><text>5,062,937</text></patcit>; <patcit id="pcit0030" dnum="US4954232A"><text>4,954,232</text></patcit>; <patcit id="pcit0031" dnum="US4948482A"><text>4,948,482</text></patcit> and <patcit id="pcit0032" dnum="US4680742A"><text>4,680,742</text></patcit>. This invention avails itself of these advantageous properties of an Si₃N₄ layer or layers. However, and in addition, it is a unique, and quite surprising, finding of this invention that when such a layer or layers of Si₃N₄ is (or are) used in combination with another selected metal(s) to make up a particular group of layer systems, that these layer systems achieve the highly desirable characteristic of being heat treatable as well. Still further, it has also been surprisingly found that, whether through synergism or some other unknown mechanism, Si₃N₄ is employed with such selected metal layer(s) to make up these layer systems, a significant improvement in chemical resistance is experienced, particularly as compared with the prior, known and highly regarded high content Ni layer systems of the aforesaid <patcit id="pcit0033" dnum="US5229194A"><text>U.S. Patent No. 5,229,194</text></patcit>.

0038In the practice of this invention it is believed that the metal employed (as M, M/O and/or MO_x) in combination with Si₃N₄ should be selected from a rather narrow group of alternatives in order to achieve the desired results of heat treatability, durability and chemical resistance, while at the same time achieving the necessary color and solar management properties desired.

0039It is a requirement, however, for this invention, that while some small or minor amount of oxidation may be tolerated in the nickel-containing layer(s), the nickel-containing layer(s) must remain substantially free of any nitride so as to be sufficiently chemically resistant to satisfy most needs. In this respect, while nitrides do not significantly interfere with the achievement of heat treatability in most instances, the formation of such a nitride has been found to reduce chemical durability as measured by the aforesaid 5% HCl boil test.

0040Of course, high content nickel/chromium alloys remain useful in this invention. Such consist of 80/20 by weight Ni/Cr and Haynes 214 Alloy whose nominal composition by weight consists essentially of: <tables id="tabl0003" num="0003"><table frame="all"><tgroup cols="2" rowsep="0"><colspec colnum="1" colname="col1" colwidth="17mm" /><colspec colnum="2" colname="col2" colwidth="26mm" /><thead valign="top"><row rowsep="1"><entry align="center">Element</entry><entry align="center">(approx) Wt. %</entry></row></thead><tbody><row><entry>Ni</entry><entry align="char" char="." charoff="14">75.45</entry></row><row><entry>Fe</entry><entry align="char" char="." charoff="14">4.00</entry></row><row><entry>Cr</entry><entry align="char" char="." charoff="14">16.00</entry></row><row><entry>C</entry><entry align="char" char="." charoff="14">.04</entry></row><row><entry>Al</entry><entry align="char" char="." charoff="14">4.50</entry></row><row rowsep="1"><entry>Y</entry><entry align="char" char="." charoff="14">.01</entry></row></tbody></tgroup></table></tables>

0041With reference now to the drawings, <figref idref="f0001">Figures 1A and 1B</figref> illustrate one particular type of heat treatable layer system contemplated herein. In these two figures, a nickel containing metal "M" virtually free of any oxidation or nitride has been formed by sputter coating (e.g. to a thickness of about 50 to 300 Å). In <figref idref="f0001">Figure 1A</figref> this metallic layer is simply overcoated by sputter coating with Si₃N₄ (e.g. about 10 to 750 A thick). In <figref idref="f0001">Figure 1B</figref> an undercoat of Si₃N₄ was first sputter coated onto the glass substrate (e.g. to a thickness of about 10 to 750 Å).

0042The layer system of <figref idref="f0001">Figure 2A</figref> is similar to that of <figref idref="f0001">Figure 1A</figref> and the layer system of <figref idref="f0001">Figure 2B</figref> is similar to that of <figref idref="f0001">Figure 1B</figref> except that, by the designation "M/O" it is indicated that an acceptable heat treatable layer system can be achieved despite the existence of a small amount of oxidation having been formed in the metallic layer. While not precisely quantifiable, in certain instances as much as about 15% oxygen in the sputter-coating gas may be tolerated and still achieve the desired results of this invention. The layer thicknesses here are the same as in <figref idref="f0001">Figures 1A and 1B</figref> respectively.

0043<figref idref="f0001">Figures 3A and 3B</figref> show a family of layer systems in accordance with this invention. Here, whether only overcoated with Si₃N₄ (<figref idref="f0001">Figure 3A</figref>) or in addition, undercoated as well with Si₃N₄ (<figref idref="f0001">Figure 3B</figref>) stoichiometric metal oxide layers MO_x surround the substantially metallic layer M/O. The layers are sputter coated to the thicknesses within the guidelines given above.

0044<figref idref="f0001">Figures 4A and 4B</figref> illustrate yet another family of layer systems contemplated by this invention. Here two layers of metal "M", or slightly oxidized metal "M/O" are separated, and surrounded by layers of Si₃N₄. Once again, the layers are sputter coated to thicknesses within the guidelines given above.

0045<figref idref="f0001">Figure 6</figref> is a combined hybrid of the families of <figref idref="f0001">Figures 3A,B and 4A,B</figref>, in that here there are two metallic layers M/O, each surrounded by stoichiometric oxide layers MO_x which in turn are surrounded by three layers, Si₃N₄. Again the layers are sputter coated to thicknesses within the guidelines given above.

0046<figref idref="f0001">Figures 5A and 5B</figref> set forth another family of layer systems according to this invention. Here the metallic layer is overcoated (alone, <figref idref="f0001">Figure 5A</figref>) or optionally undercoated as well (<figref idref="f0001">Figure 5B</figref>) with Si₃N₄ as in the other families. However, in this embodiment substantially pure nickel has been admixed with Si₃N₄ as the separate metal layer. This intermediate Ni/Si₃N₄ layer uniquely serves in certain circumstances to achieve desired solar management characteristics yet is highly durable, heat treatable, and abrasion resistant. The weight percent of Ni in the preferred embodiments is about 80 to 90%, the remainder being Si₃N₄.

0047The layer systems of this invention may be formed by any conventional sputter-coating technique, using for example, a conventional sputter coater such as an Airco-Temescal multi-zone sputter coater of known design. One preferred way, however, of forming the coatings of this invention is to use the unique techniques and targets as disclosed in our copending application Serial No.<patcit id="pcit0034" dnum="WO08102585A"><text>08/102,585</text></patcit> now <patcit id="pcit0035" dnum="US5403458A"><text>US-A-5,403,458</text></patcit> entitled "Sputter Coating Target and Method of Use", filed on even date herewith. The entire disclosure of this copending application is incorporated herein by reference. Generally speaking, and as disclosed in this copending application, a unique sputter-coated target for producing Si₃N₄ layers is employed to overcome the problem of coating the anode with a non-conductive layer (e.g. of Si₃N₄). This is accomplished by uniformly mixing with the Si of the target another element, in small quantities, which will render the ultimate layer formed (and thus the layer formed on the anode) conductive...thereby alleviating the anode reconditioning downtime problem prevalent in the art.

0048In the practice of the subject invention where heat treatability, solar management, durability and abrasion resistance are desired characteristics in the layer system, care must be taken in choosing the conductive element to be admixed with the Si in the target so as not to defeat, in the ultimate Si₃N₄ layer formed, its purposes and characteristics. Thus, in the practice of this invention it is preferred for most systems contemplated that the conductive element used will be limited to small amounts, usually less than abut 10% and preferably less than about 5%. Such elements furthermore should generally be highly resistant to oxidation. Metals such as gold, platinum and nickel may be employed. Preferred, however, for most purposes contemplated herein are the metals titanium, zirconium, chromium, hafnium, and mixtures thereof. These elements are preferred because they generally form nitrides which are electrically conductive and, optically as well as mechanically, do not interfere (and are compatible with) the primary material Si₃N₄. To the extent they form nitrides, however, the amount of such a nitride formed is to be minimized. To the extent that any silicide is formed of these metals it is believed that it is an intermediate which quickly breaks down into its respective nitrides, but in any event is compatible with and does not optically or mechanically interfere with the Si₃N₄ is any event, to the extent that it may remain.

0049A particularly preferred target for use herein is an Si target doped with about 5% titanium. It has been found that the resultant layer(s) formed (e.g. the Si₃N₄ illustrated in <figref idref="f0001">Figures 1-6</figref>) comprise(s) about 95% Si₃N₄, the remainder being titanium nitride. This small amount of titanium nitride has been found not to interfere materially with the optical, mechanical, chemical, color or heat treatable characteristics desired in the practice of this invention. In like manner, furthermore, the nitride of zirconium, chromium or hafnium can also be tolerated for the purposes cf achieving production efficiency in approximately the same amounts.

0050This invention will now be described with respect to certain examples thereof:

EXAMPLES

0051The following layer systems were sputter coated onto clear glass substrates using Si target(s) (doped with 5% aluminum) and conventional sputter coating techniques as indicated. The chemical and durability tests employed are as described above. The heat treatment employed exemplified a typical tempering process by subjecting the sample to 1265°F (685°C) for 5 minutes. Heat treatment samples were either 3" x 3" or 4" x 4" squares.

EXAMPLE 1

(Prior Art Exemplar)

0052A layer system of a prior art exemplar such as falls within the scope of our aforesaid <patcit id="pcit0036" dnum="US5229194A"><text>U.S. Patent No. 5,229,194</text></patcit>, was formed by sputter coating. The layer system so formed from glass outward was SnO₂/MO_x/M/O/MO_x/SnO₂ wherein M = Haynes 214 Alloy. The product showed excellent heat treatability and an R_s of 79 ohms/sq. However, it failed the chemical resistance test (i.e. 5% HCl boil at 220°F for 1 hour) before heat treatment at 5 minutes and at 12 minutes after heat treatment. The Taber abrasion test was passed in that there was a 7.6% change in transmission prior to heat treatment at 300 revolutions, but only a 1.2% change in transmission after heat treatment at 300 revolutions. This evidenced quite acceptable mechanical durability characteristics. Despite its somewhat low chemical resistance as determined by the boil test, this prior art coating system has proven to be an excellent heat treatable coating for many applications where very reduced visible transmission is required, and this kind of chemical resistant is of little or no concern. An example of such use is in "privacy" windows in automobiles. In this respect visible transmittance of this prior art exemplary is about 23%.

EXAMPLES 2-24

0053A series of layered films was now made for comparison purposes using standard sputter coating techniques and thicknesses within the above guidelines. The results are as follows: <tables id="tabl0004" num="0004"><table frame="all"><tgroup cols="4" rowsep="0"><colspec colnum="1" colname="col1" colwidth="23mm" /><colspec colnum="2" colname="col2" colwidth="92mm" /><colspec colnum="3" colname="col3" colwidth="27mm" /><colspec colnum="4" colname="col4" colwidth="17mm" /><thead valign="top"><row rowsep="1"><entry align="center">Example No.</entry><entry>Layer System</entry><entry align="center">Heat Treatment</entry><entry align="center">Acid Boil</entry></row></thead><tbody><row><entry align="right">2</entry><entry>SNO₂/214OX/214-0/214OX/SNO₂/Si₃N₄</entry><entry align="center">F</entry><entry align="right">F</entry></row><row><entry align="right">3</entry><entry>SNO₂/214OX/214-0/214OX/Si₃N₄</entry><entry align="center">P</entry><entry align="right">P</entry></row><row><entry align="right">4</entry><entry>SNO2/214OX/214-0/214OX/Si₃N₄/SNO₂</entry><entry align="center" /><entry align="right">PP</entry></row><row><entry align="right">5</entry><entry>Si₃N₄/214OX/214-0/214OX/Si₃N₄</entry><entry align="center">P</entry><entry align="right">P</entry></row><row><entry align="right">6</entry><entry>Si₃N₄/214/Si₃N₄</entry><entry align="center">P</entry><entry align="right">P</entry></row><row><entry align="right">7</entry><entry>Si₃N₄/214-N/Si₃N₄</entry><entry align="center">P</entry><entry align="right">F</entry></row><row><entry align="right">8</entry><entry>Si₃N₄/214-N/Si₃N₄</entry><entry align="center">P</entry><entry align="right">F</entry></row><row><entry align="right">9</entry><entry>Si₃N₄/214-N/Si₃N₄</entry><entry align="center">P</entry><entry align="right">F</entry></row><row><entry align="right">10</entry><entry>Si₃N₄/214/Si₃N₄</entry><entry align="center">P</entry><entry align="right">P</entry></row><row><entry align="right">11</entry><entry>Si₃N₄/214OX/214-0/214OX/Si₃N₄**</entry><entry align="center" /><entry /></row><row><entry align="right">12</entry><entry>Si₃N₄/214/Si₃N₄/214/Si₃N₄</entry><entry align="center" /><entry align="right">PP</entry></row><row><entry align="right">13</entry><entry>Si₃N₄/214/Si₃N₄/214/Si₃N₄</entry><entry align="center" /><entry align="right">PP</entry></row><row><entry align="right">14</entry><entry>Si₃N₄/214OX/214-0/214OX/Si₃N₄/214OX/214-0/214OX/Si3N₄</entry><entry align="center">P</entry><entry align="right">P</entry></row><row><entry align="right">15</entry><entry>Si₃N₄/214OX/214-0/214OX/Si₃N₄/214OX/214-0/214OX/Si₃N₄</entry><entry align="center">P</entry><entry align="right">P</entry></row><row><entry align="right">16</entry><entry>Si₃N₄/214-O/Si₃N₄</entry><entry align="center">P</entry><entry align="right">P</entry></row><row><entry align="right">17</entry><entry>***Si₃N₄/Ni/Si₃N₄</entry><entry align="center">P</entry><entry align="right">P</entry></row><row><entry align="right">18</entry><entry>Si₃N₄/Ni/Si₃N₄/Ni/Si₃N₄</entry><entry align="center">P</entry><entry align="right">P</entry></row><row><entry align="right">19</entry><entry>Si₃N₄/Ni/Si₃N₄/Ni/Si₃N₄</entry><entry align="center">P</entry><entry align="right">P</entry></row><row><entry align="right">20</entry><entry>Si₃N₄/SS-316/Si₃N₄</entry><entry align="center">P</entry><entry align="right">-</entry></row><row><entry align="right">21</entry><entry>Si₃N₄/SS-316/SNO₂</entry><entry align="center">F</entry><entry align="right">-</entry></row><row><entry align="right">22</entry><entry>Si₃N₄/(80/20)/Si₃N₄</entry><entry align="center">P</entry><entry align="right">P</entry></row><row><entry align="right">23</entry><entry>****Si₃N₄/(80/20)-0/Si₃N₄</entry><entry align="center">P</entry><entry align="right">P</entry></row><row rowsep="1"><entry align="right">24</entry><entry>Si₃N₄/(80/20)-0/Si₃N₄</entry><entry align="center">P</entry><entry align="right">P</entry></row></tbody></tgroup><tgroup cols="4" colsep="0" rowsep="0"><colspec colnum="1" colname="col1" colwidth="23mm" /><colspec colnum="2" colname="col2" colwidth="92mm" /><colspec colnum="3" colname="col3" colwidth="27mm" /><colspec colnum="4" colname="col4" colwidth="17mm" /><tbody><row><entry namest="col1" nameend="col4" align="justify">*P = Passed test *PP = Passed test both before and after heat treatment *F = Failed test **This layer system was tested and passed the Taber test both before and after heat treatment</entry></row><row><entry namest="col1" nameend="col4" align="justify">***This layer system exhibited low emittance characteristics (E_n=17)</entry></row><row><entry namest="col1" nameend="col4" align="justify">****80/20 is an alloy of 80% Ni and 20% Cr by weight</entry></row></tbody></tgroup></table></tables> Examples 20 and 21 are comparative examples, only.

0054Examples 22-24 in the above table (reported here as 2A, B, C) were formed in the following way on an ILS-1600 Airco sputter coater using 5/32" clear glass. The following conditions were employed: <tables id="tabl0005" num="0005"><table frame="all"><tgroup cols="7"><colspec colnum="1" colname="col1" colwidth="17mm" /><colspec colnum="2" colname="col2" colwidth="20mm" /><colspec colnum="3" colname="col3" colwidth="30mm" /><colspec colnum="4" colname="col4" colwidth="22mm" /><colspec colnum="5" colname="col5" colwidth="21mm" /><colspec colnum="6" colname="col6" colwidth="22mm" /><colspec colnum="7" colname="col7" colwidth="21mm" /><thead valign="top"><row><entry rowsep="0" align="center">Line No.</entry><entry rowsep="0" align="center">Film Layer</entry><entry rowsep="0" align="center">Base Pressure IG</entry><entry namest="col4" nameend="col5" align="left">GAS 1: Ar</entry><entry namest="col6" nameend="col7" align="left">GAS 2: N₂ (O₂)</entry></row><row><entry /><entry /><entry /><entry align="center">Flow (sccm)</entry><entry align="center">Cap. Mono.</entry><entry align="center">Flow (sccm)</entry><entry align="center">Cap. Mono.</entry></row></thead><tbody><row><entry>1</entry><entry>Si₃N₄</entry><entry align="char" char="." charoff="6">4.1x10^-6</entry><entry align="right">25</entry><entry>5.5x10^-4</entry><entry>25</entry><entry align="char" char="." charoff="9">8.8x10^-4</entry></row><row><entry>2A</entry><entry>80/20</entry><entry align="char" char="." charoff="6">2.0x10^-6</entry><entry align="right">40</entry><entry>6.9x10^-4</entry><entry /><entry /></row><row><entry>2B</entry><entry>80/20-0</entry><entry align="char" char="." charoff="6">1.5x10^-6</entry><entry align="right">40</entry><entry>7.1x10^-4</entry><entry>3 (O₂)</entry><entry align="char" char="." charoff="9">7.5x10^-4</entry></row><row><entry>2C</entry><entry>80/20-0</entry><entry align="char" char="." charoff="6">2.0x10^-6</entry><entry align="right">40</entry><entry>7.1x10^-4</entry><entry>6 (O₂)</entry><entry align="char" char="." charoff="9">7.8x10^-4</entry></row><row><entry>3</entry><entry>Si₃N₄</entry><entry align="char" char="." charoff="6">2.5x10^-6</entry><entry align="right">25</entry><entry>5/8x1-^-4</entry><entry>25</entry><entry align="char" char="." charoff="9">9.0x10^-4</entry></row></tbody></tgroup></table></tables><tables id="tabl0006" num="0006"><table frame="all"><tgroup cols="9"><colspec colnum="1" colname="col1" colwidth="17mm" /><colspec colnum="2" colname="col2" colwidth="18mm" /><colspec colnum="3" colname="col3" colwidth="18mm" /><colspec colnum="4" colname="col4" colwidth="18mm" /><colspec colnum="5" colname="col5" colwidth="20mm" /><colspec colnum="6" colname="col6" colwidth="20mm" /><colspec colnum="7" colname="col7" colwidth="20mm" /><colspec colnum="8" colname="col8" colwidth="19mm" /><colspec colnum="9" colname="col9" colwidth="20mm" /><thead valign="top"><row><entry rowsep="0" align="center">Line No.</entry><entry rowsep="0" align="center">Film Layer</entry><entry rowsep="0" align="center">Drive Motor Speed %</entry><entry namest="col4" nameend="col7" align="left">Cathode Parameters</entry><entry rowsep="0" align="center">Voltage Under Cathode</entry><entry rowsep="0" align="center">Sputter Pressure IG 1</entry></row><row><entry /><entry /><entry /><entry align="center">% Power Level</entry><entry align="center">Voltage Load Lock</entry><entry align="center">Power KW</entry><entry align="center">DC AMPS</entry><entry /><entry /></row></thead><tbody><row><entry>1</entry><entry>Si₃N₄</entry><entry>35x16</entry><entry align="char" char=".">7.0</entry><entry align="right">420</entry><entry align="char" char="." charoff="10">2.9</entry><entry align="char" char="." charoff="10">7.0</entry><entry align="right">424</entry><entry>5.5x 10^-4</entry></row><row><entry>2A</entry><entry>80/20</entry><entry>35x2</entry><entry align="char" char=".">8.5</entry><entry align="right">473</entry><entry align="char" char="." charoff="10">4.0</entry><entry align="char" char="." charoff="10">8.7</entry><entry align="right">477</entry><entry>5.0x 10^-4</entry></row><row><entry>2B</entry><entry>80/20-0</entry><entry>35x2</entry><entry align="char" char=".">8.5</entry><entry align="right">486</entry><entry align="char" char="." charoff="10">4.2</entry><entry align="char" char="." charoff="10">8.7</entry><entry align="right">490</entry><entry>5.3x 10^-4</entry></row><row><entry>2C</entry><entry>80/20-0</entry><entry>35x2</entry><entry align="char" char=".">8.5</entry><entry align="right">501</entry><entry align="char" char="." charoff="10">4.2</entry><entry align="char" char="." charoff="10">8.7</entry><entry align="right">503</entry><entry>5.0x 10^-4</entry></row><row><entry>3</entry><entry>Si₃N₄</entry><entry>35x8</entry><entry align="char" char=".">7.0</entry><entry align="right">424</entry><entry align="char" char="." charoff="10">2.9</entry><entry align="char" char="." charoff="10">7.0</entry><entry align="right">426</entry><entry>5.7x 10^-4</entry></row></tbody></tgroup></table></tables>

0055Example 24 had an E_n (at 10 microns) before heat treatment of 0.34 and an R_s of 58.1. After heat treatment the R_s was 28.0 and the E_n was 0.23. Illuminant C 2° observer values before and after heat treatment were as follows: <tables id="tabl0007" num="0007"><table frame="all"><tgroup cols="3" rowsep="0"><colspec colnum="1" colname="col1" colwidth="19mm" /><colspec colnum="2" colname="col2" colwidth="20mm" /><colspec colnum="3" colname="col3" colwidth="21mm" /><thead valign="top"><row rowsep="1"><entry namest="col1" nameend="col3" align="left">Before heat treatment:</entry></row></thead><tbody><row><entry align="right">TY 19.42</entry><entry align="right">RGY 16.11</entry><entry align="right">RFY 34.48</entry></row><row><entry align="right">x .2873</entry><entry align="right">x .3259</entry><entry align="right">x .3459</entry></row><row><entry align="right">y .2967</entry><entry align="right">y .3255</entry><entry align="right">y .3556</entry></row><row><entry align="right">a -1.24</entry><entry align="right">a -1.87</entry><entry align="right">a -0.96</entry></row><row rowsep="1"><entry align="right">b -6.77</entry><entry align="right">b -3.53</entry><entry align="right">b +15.11</entry></row></tbody></tgroup></table></tables><tables id="tabl0008" num="0008"><table frame="all"><tgroup cols="3" rowsep="0"><colspec colnum="1" colname="col1" colwidth="19mm" /><colspec colnum="2" colname="col2" colwidth="21mm" /><colspec colnum="3" colname="col3" colwidth="21mm" /><thead valign="top"><row rowsep="1"><entry namest="col1" nameend="col3" align="left">After heat treatment:</entry></row></thead><tbody><row><entry align="right">TY 26.28</entry><entry align="right">RGY 12.61</entry><entry align="right">RFY 28.36</entry></row><row><entry align="right">x .2869</entry><entry align="right">x .3209</entry><entry align="right">x .3558</entry></row><row><entry align="right">y .2986</entry><entry align="right">y .3173</entry><entry align="right">y .3641</entry></row><row><entry align="right">a -2.17</entry><entry align="right">a +2.58</entry><entry align="right">a -0.41</entry></row><row rowsep="1"><entry align="right">b -7.04</entry><entry align="right">b +1.19</entry><entry align="right">b +17.54</entry></row></tbody></tgroup></table></tables>

0056All three products were found to be heat treatable, durable and chemically resistant.

0057Example 17 in the above table was formed in a similar fashion using 5/32" clear glass with slight variations in operating conditions as indicated below so as to make up three samples a, b, c. The sputtering of the Ni layer included a startup with 10% O₂ with heatup for 10 minutes, then shutoff. All samples were heat treatable, chemically resistant and durable. The operating conditions were as follows: <tables id="tabl0009" num="0009"><table frame="all"><tgroup cols="7"><colspec colnum="1" colname="col1" colwidth="17mm" /><colspec colnum="2" colname="col2" colwidth="20mm" /><colspec colnum="3" colname="col3" colwidth="30mm" /><colspec colnum="4" colname="col4" colwidth="22mm" /><colspec colnum="5" colname="col5" colwidth="21mm" /><colspec colnum="6" colname="col6" colwidth="22mm" /><colspec colnum="7" colname="col7" colwidth="21mm" /><thead valign="top"><row><entry rowsep="0" align="center">Line No.</entry><entry rowsep="0" align="center">Film Layer</entry><entry rowsep="0" align="center">Base Pressure IG</entry><entry namest="col4" nameend="col5" align="left">GAS 1: Ar</entry><entry namest="col6" nameend="col7" align="left">GAS 2: N₂</entry></row><row><entry /><entry /><entry /><entry align="center">Flow (sccm)</entry><entry align="center">Cap. Mono.</entry><entry align="center">Flow (sccm)</entry><entry align="center">Cap. Mono.</entry></row></thead><tbody><row><entry>1</entry><entry>Si₃N₄</entry><entry align="char" char="." charoff="6">7.8x10^-6</entry><entry align="right">25</entry><entry align="char" char="." charoff="9">4.8x10^-4</entry><entry align="right">25</entry><entry align="char" char="." charoff="9">7.1x10^-4</entry></row><row><entry>2a</entry><entry>Ni</entry><entry align="char" char="." charoff="6">6.0x10^-6</entry><entry align="right">80</entry><entry align="char" char="." charoff="9">1.6x10^-3</entry><entry /><entry /></row><row><entry>2b</entry><entry>Ni</entry><entry align="char" char="." charoff="6">8.4x10^-6</entry><entry align="right">80</entry><entry align="char" char="." charoff="9">1.6x10^-3</entry><entry /><entry /></row><row><entry>2c</entry><entry>Ni</entry><entry align="char" char="." charoff="6">2.2x10^-6</entry><entry align="right">80</entry><entry align="char" char="." charoff="9">1.6x10^-3</entry><entry /><entry /></row><row><entry>3</entry><entry>Si₃N₄</entry><entry align="char" char="." charoff="6">8.4x10^-6</entry><entry align="right">25</entry><entry align="char" char="." charoff="9">5.4x10^-4</entry><entry align="right">25</entry><entry align="char" char="." charoff="9">8.2x10^-4</entry></row></tbody></tgroup></table></tables><tables id="tabl0010" num="0010"><table frame="all"><tgroup cols="9"><colspec colnum="1" colname="col1" colwidth="17mm" /><colspec colnum="2" colname="col2" colwidth="19mm" /><colspec colnum="3" colname="col3" colwidth="18mm" /><colspec colnum="4" colname="col4" colwidth="18mm" /><colspec colnum="5" colname="col5" colwidth="20mm" /><colspec colnum="6" colname="col6" colwidth="20mm" /><colspec colnum="7" colname="col7" colwidth="20mm" /><colspec colnum="8" colname="col8" colwidth="19mm" /><colspec colnum="9" colname="col9" colwidth="20mm" /><thead valign="top"><row><entry rowsep="0" align="center">Line No.</entry><entry rowsep="0" align="center">Film Layer</entry><entry rowsep="0" align="center">Drive Motor Speed %</entry><entry namest="col4" nameend="col7" align="left">Cathode Parameters</entry><entry rowsep="0" align="center">Voltage Under Cathode</entry><entry rowsep="0" align="center">Sputter Pressure IG 1</entry></row><row><entry /><entry /><entry /><entry align="center">% Power Level</entry><entry align="center">Voltage Load Lock</entry><entry align="center">Power KW</entry><entry align="center">DC AMPS</entry><entry /><entry /></row></thead><tbody><row><entry>1</entry><entry>Si₃N₄</entry><entry>35x16</entry><entry align="char" char=".">7.0</entry><entry align="right">422</entry><entry align="char" char="." charoff="10">2.9</entry><entry align="char" char="." charoff="10">7.0</entry><entry align="right">425</entry><entry>4.5x 10^-4</entry></row><row><entry>2a</entry><entry>Ni</entry><entry>35x1</entry><entry align="char" char=".">8.5</entry><entry align="right">562</entry><entry align="char" char="." charoff="10">5.3</entry><entry align="char" char="." charoff="10">9.5</entry><entry align="right">564</entry><entry>8.8x 10^-4</entry></row><row><entry>2b</entry><entry>Ni</entry><entry>35x2</entry><entry align="char" char=".">6.0</entry><entry align="right">543</entry><entry align="char" char="." charoff="10">3.8</entry><entry align="char" char="." charoff="10">7.0</entry><entry align="right">545</entry><entry>8.9x 10^-4</entry></row><row><entry>2c</entry><entry>Ni</entry><entry>35x2</entry><entry align="char" char=".">7.0</entry><entry align="right">547</entry><entry align="char" char="." charoff="10">4.1</entry><entry align="char" char="." charoff="10">7.5</entry><entry align="right">550</entry><entry>7.5x 10^-4</entry></row><row><entry>3</entry><entry>Si₃N₄</entry><entry>35x8</entry><entry align="char" char=".">7.0</entry><entry align="right">429</entry><entry align="char" char="." charoff="10">2.9</entry><entry align="char" char="." charoff="10">7.0</entry><entry align="right">428</entry><entry>4.3x 10^-4</entry></row></tbody></tgroup></table></tables>

0058For Example 17, sample C, the illuminant C 2° obs. values were determined both before and after heat treatment and were reported as follows: <tables id="tabl0011" num="0011"><table frame="all"><tgroup cols="3" rowsep="0"><colspec colnum="1" colname="col1" colwidth="19mm" /><colspec colnum="2" colname="col2" colwidth="21mm" /><colspec colnum="3" colname="col3" colwidth="21mm" /><thead valign="top"><row rowsep="1"><entry namest="col1" nameend="col3" align="left">Before heat treatment:</entry></row></thead><tbody><row><entry align="right">TY 23.48</entry><entry align="right">RGY 12.74</entry><entry align="right">RFY 31.94</entry></row><row><entry align="right">x .2847</entry><entry align="right">x .3369</entry><entry align="right">x .3418</entry></row><row><entry align="right">y .2948</entry><entry align="right">y .33444</entry><entry align="right">y .3499</entry></row><row><entry align="right">a -1.56</entry><entry align="right">a -2.27</entry><entry align="right">a -0.47</entry></row><row rowsep="1"><entry align="right">b -7.97</entry><entry align="right">b +6.02</entry><entry align="right">b +12.77</entry></row></tbody></tgroup></table></tables><tables id="tabl0012" num="0012"><table frame="all"><tgroup cols="3" rowsep="0"><colspec colnum="1" colname="col1" colwidth="19mm" /><colspec colnum="2" colname="col2" colwidth="21mm" /><colspec colnum="3" colname="col3" colwidth="21mm" /><thead valign="top"><row rowsep="1"><entry namest="col1" nameend="col3" align="left">After heat treatment:</entry></row></thead><tbody><row><entry align="right">TY 22.44</entry><entry align="right">RGY 14.45</entry><entry align="right">RFY 32.41</entry></row><row><entry align="right">x .2835</entry><entry align="right">x .3370</entry><entry align="right">x .3390</entry></row><row><entry align="right">y .2932</entry><entry align="right">y .3367</entry><entry align="right">y .3461</entry></row><row><entry align="right">a -1.41</entry><entry align="right">a +1.78</entry><entry align="right">a -0.17</entry></row><row rowsep="1"><entry align="right">b -8.37</entry><entry align="right">b +6.72</entry><entry align="right">b +11.48</entry></row></tbody></tgroup></table></tables>

0059Sheet resistance R_s before heat treatment was 23.5 and after heat treatment was 17.0. Normal emittance (E_n) before heat treatment was 0.24 and after heat treatment was 0.17. Example 17 was heat treatable, durable and chemically resistant.

0060With reference now to Example 11, in the above table, an 8"x8" sample of 5/32" thick clear glass was formed by the sputter coater under the following conditions: <tables id="tabl0013" num="0013"><img file="EP0747329B2_D0002.tif" /></tables>

0061Sheet resistance before heat treatment was 82.6 and after heat treatment was 46.1. Normal emittance (E_n) before heat treatment was 0.48 and after heat treatment was 0.33. Before and after Ill. C 2° observer data was reported as follows: <tables id="tabl0014" num="0014"><table frame="all"><tgroup cols="3" rowsep="0"><colspec colnum="1" colname="col1" colwidth="19mm" /><colspec colnum="2" colname="col2" colwidth="21mm" /><colspec colnum="3" colname="col3" colwidth="21mm" /><thead valign="top"><row rowsep="1"><entry namest="col1" nameend="col3" align="left">Before heat treatment:</entry></row></thead><tbody><row><entry align="right">TY 26.04</entry><entry align="right">RGY 12.29</entry><entry align="right">RFY 29.27</entry></row><row><entry align="right">x .2869</entry><entry align="right">x .3319</entry><entry align="right">x .3436</entry></row><row><entry align="right">y .2958</entry><entry align="right">y .3327</entry><entry align="right">y .3527</entry></row><row><entry align="right">a -1.17</entry><entry align="right">a +1.40</entry><entry align="right">a -0.74</entry></row><row rowsep="1"><entry align="right">b -7.76</entry><entry align="right">b +5.15</entry><entry align="right">b +13.30</entry></row></tbody></tgroup></table></tables><tables id="tabl0015" num="0015"><table frame="all"><tgroup cols="3" rowsep="0"><colspec colnum="1" colname="col1" colwidth="19mm" /><colspec colnum="2" colname="col2" colwidth="21mm" /><colspec colnum="3" colname="col3" colwidth="21mm" /><thead valign="top"><row rowsep="1"><entry namest="col1" nameend="col3" align="left">After heat treatment:</entry></row></thead><tbody><row><entry align="right">TY 28.34</entry><entry align="right">RGY 11.54</entry><entry align="right">RFY 26.69</entry></row><row><entry align="right">x .2895</entry><entry align="right">x .3321</entry><entry align="right">x .3395</entry></row><row><entry align="right">y .2988</entry><entry align="right">y .3341</entry><entry align="right">y .3472</entry></row><row><entry align="right">a -1.34</entry><entry align="right">a +1.09</entry><entry align="right">a -0.31</entry></row><row rowsep="1"><entry align="right">b -6.88</entry><entry align="right">b +5.32</entry><entry align="right">b +11.09</entry></row></tbody></tgroup></table></tables>

0062The Taber test prior to heat treatment showed a change of 7.6%. After heat treatment the change was only 1.2%. The product produced was heat treatable, durable and chemically resistant.

0063Examples 12 and 13, from the above table, were formed in a similar fashion and showed superior heat treatability characteristics and excellent chemical resistance. Example 12 was dark and Example 13 was not. The operating conditions were as follows: <u>For Both Examples 12 and 13</u><tables id="tabl0016" num="0016"><table frame="all"><tgroup cols="7"><colspec colnum="1" colname="col1" colwidth="17mm" /><colspec colnum="2" colname="col2" colwidth="20mm" /><colspec colnum="3" colname="col3" colwidth="30mm" /><colspec colnum="4" colname="col4" colwidth="15mm" /><colspec colnum="5" colname="col5" colwidth="17mm" /><colspec colnum="6" colname="col6" colwidth="15mm" /><colspec colnum="7" colname="col7" colwidth="17mm" /><thead><row><entry valign="top">Line No.</entry><entry valign="top">Film Layer</entry><entry valign="top">Base Pressure IG I</entry><entry namest="col4" nameend="col5" align="left" valign="top">Gas 1: Ar</entry><entry namest="col6" nameend="col7" align="left" valign="top">Gas 2: N2</entry></row><row><entry valign="top" /><entry valign="top" /><entry valign="top" /><entry valign="top">Flow (sccm)</entry><entry valign="top">Cap. Mono.</entry><entry valign="top">Flow (sccm)</entry><entry valign="top">Cap. Mono.</entry></row></thead><tbody><row><entry>1</entry><entry>Si₃N₄</entry><entry>3.4x10^-6</entry><entry>25</entry><entry>4.7x10^-4</entry><entry>25</entry><entry>8.0x10^-4</entry></row><row><entry>2</entry><entry>214</entry><entry>1.6x10^-6</entry><entry>40</entry><entry>6.0x10^-4</entry><entry /><entry /></row><row><entry>3</entry><entry>Si₃N₄</entry><entry>1.3x10^-6</entry><entry>25</entry><entry>4.6x10^-4</entry><entry>25</entry><entry>8.0x10^-4</entry></row><row><entry>4</entry><entry>214</entry><entry>1.1x10^-6</entry><entry>40</entry><entry>6.3x10^-4</entry><entry /><entry /></row><row><entry>5</entry><entry>Si₃N₄</entry><entry>9.8x10^-7</entry><entry>25</entry><entry>5.0x10^-4</entry><entry>25</entry><entry>8.2x10^-4</entry></row></tbody></tgroup></table></tables>

0064<u>Examples 12 and 13 represented as A and B respectively</u><tables id="tabl0017" num="0017"><table frame="all"><tgroup cols="9"><colspec colnum="1" colname="col1" colwidth="17mm" /><colspec colnum="2" colname="col2" colwidth="20mm" /><colspec colnum="3" colname="col3" colwidth="30mm" /><colspec colnum="4" colname="col4" colwidth="25mm" /><colspec colnum="5" colname="col5" colwidth="30mm" /><colspec colnum="6" colname="col6" colwidth="20mm" /><colspec colnum="7" colname="col7" colwidth="19mm" /><colspec colnum="8" colname="col8" colwidth="37mm" /><colspec colnum="9" colname="col9" colwidth="34mm" /><thead><row><entry morerows="1" valign="top">Line No.</entry><entry morerows="1" valign="top">Film Layer</entry><entry morerows="1" valign="top">Drive Motor Speed %</entry><entry namest="col4" nameend="col7" align="left" valign="top">Cathode Parameters</entry><entry morerows="1" valign="top">Voltage under Cathode</entry><entry morerows="1" valign="top">Sputter Pressure IG I</entry></row><row><entry valign="top">% Power Level</entry><entry valign="top">Voltage Load Lock</entry><entry valign="top">Power KW</entry><entry valign="top">DC AMPS</entry></row></thead><tbody><row><entry>1</entry><entry>Si₃N₄</entry><entry>35x16</entry><entry align="char" char=".">7.0</entry><entry>430</entry><entry>3.0</entry><entry align="char" char=".">7.1</entry><entry>432</entry><entry>4.8x10^-4</entry></row><row><entry>2A</entry><entry>214</entry><entry>35x2</entry><entry align="char" char=".">5.0</entry><entry>396</entry><entry>2.6</entry><entry align="char" char=".">6.4</entry><entry>401</entry><entry>3.9x10^-4 - 4.0</entry></row><row><entry>2B</entry><entry>214</entry><entry>35x2</entry><entry align="char" char=".">4.3</entry><entry>376</entry><entry>1.8</entry><entry align="char" char=".">4.6</entry><entry>379</entry><entry>4.1x10^-4</entry></row><row><entry>3</entry><entry>Si₃N₄</entry><entry>35x8</entry><entry align="char" char=".">7.0</entry><entry>431</entry><entry>3.0</entry><entry align="char" char=".">7.0</entry><entry>434</entry><entry>4.6x10^-4</entry></row><row><entry>4A</entry><entry>214</entry><entry>35x2</entry><entry align="char" char=".">5.0</entry><entry>398</entry><entry>2.6</entry><entry align="char" char=".">6.4</entry><entry>397</entry><entry>3.9x10^-4 - 4.0</entry></row><row><entry>4B</entry><entry>214</entry><entry>35x2</entry><entry align="char" char=".">4.3</entry><entry>376</entry><entry>1.8</entry><entry align="char" char=".">4.6</entry><entry>379</entry><entry>4.1x10^-4</entry></row><row><entry>5</entry><entry>Si₃N₄</entry><entry>35x8</entry><entry align="char" char=".">7.0</entry><entry>431</entry><entry>3.0</entry><entry align="char" char=".">7.0</entry><entry>433</entry><entry>4.8x10^-4</entry></row></tbody></tgroup></table></tables>

EXAMPLE 25

0065A coated glass article useful for architectural or automotive purpose was formed on a production sputter coater using a typical 5/32" float glass and Haynes 214 as the metal "M". <figref idref="f0001">Figure 1B</figref> represents the resultant layer system wherein the Si₃N₄ undercoat was approximately 550 A thick, the Haynes 214 layer was approximately 100 Å thick and the Si₃N₄ overcoat was approximately 275 A thick. A conventional Airco (Solar Products)-Temescal Multi-Zone Architectural Sputter Coater as illustrated in <figref idref="f0002">Figure 7</figref> was employed, and whose various parts are described in more detail in Example 26 below. The operating conditions were as follows: <tables id="tabl0018" num="0018"><table frame="all"><tgroup cols="6"><colspec colnum="1" colname="col1" colwidth="20mm" /><colspec colnum="2" colname="col2" colwidth="19mm" /><colspec colnum="3" colname="col3" colwidth="17mm" /><colspec colnum="4" colname="col4" colwidth="12mm" /><colspec colnum="5" colname="col5" colwidth="14mm" /><colspec colnum="6" colname="col6" colwidth="16mm" /><thead valign="top"><row><entry align="center">Coat Zone</entry><entry align="center">Cathode #</entry><entry>Material</entry><entry>Volts</entry><entry>Amps</entry><entry>P (KW)</entry></row></thead><tbody><row><entry morerows="5" align="center">1</entry><entry>1</entry><entry>Si</entry><entry>417</entry><entry align="char" char="." charoff="28">60.7</entry><entry align="char" char="." charoff="23">25.3</entry></row><row><entry>2</entry><entry>Si</entry><entry>428</entry><entry align="char" char="." charoff="28">97.7</entry><entry align="char" char="." charoff="23">41.8</entry></row><row><entry>3</entry><entry>Si</entry><entry>412</entry><entry align="char" char="." charoff="28">97.0</entry><entry align="char" char="." charoff="23">40.0</entry></row><row><entry>4</entry><entry>Si</entry><entry>419</entry><entry align="char" char="." charoff="28">69.8</entry><entry align="char" char="." charoff="23">29.2</entry></row><row><entry>5</entry><entry>Si</entry><entry>409</entry><entry align="char" char="." charoff="28">90.0</entry><entry align="char" char="." charoff="23">36.8</entry></row><row><entry>6</entry><entry>Si</entry><entry>448</entry><entry align="char" char="." charoff="28">92.9</entry><entry align="char" char="." charoff="23">41.6</entry></row><row><entry morerows="5" align="center">2</entry><entry>7</entry><entry>Si</entry><entry>415</entry><entry align="char" char="." charoff="28">70.7</entry><entry align="char" char="." charoff="23">29.3</entry></row><row><entry>8</entry><entry>Si</entry><entry>417</entry><entry align="char" char="." charoff="28">42.5</entry><entry align="char" char="." charoff="23">17.7</entry></row><row><entry>9</entry><entry>Si</entry><entry>431</entry><entry align="char" char="." charoff="28">86.3</entry><entry align="char" char="." charoff="23">37.2</entry></row><row><entry>10</entry><entry>Si</entry><entry>416</entry><entry align="char" char="." charoff="28">81.6</entry><entry align="char" char="." charoff="23">33.9</entry></row><row><entry>11</entry><entry>Si</entry><entry>420</entry><entry align="char" char="." charoff="28">86.3</entry><entry align="char" char="." charoff="23">36.2</entry></row><row><entry>12</entry><entry>Si</entry><entry>430</entry><entry align="char" char="." charoff="28">90.4</entry><entry align="char" char="." charoff="23">38.8</entry></row><row><entry morerows="2" align="center">3</entry><entry>31</entry><entry>214</entry><entry>469</entry><entry align="char" char="." charoff="28">36.9</entry><entry align="char" char="." charoff="23">17.3</entry></row><row><entry>32</entry><entry>214</entry><entry>462</entry><entry align="char" char="." charoff="28">36.7</entry><entry align="char" char="." charoff="23">17.0</entry></row><row><entry>33</entry><entry>214</entry><entry>463</entry><entry align="char" char="." charoff="28">36.1</entry><entry align="char" char="." charoff="23">16.7</entry></row><row><entry align="center">4</entry><entry>19</entry><entry>214</entry><entry>426</entry><entry align="char" char="." charoff="28">18.9</entry><entry align="char" char="." charoff="23">8.1</entry></row><row><entry morerows="5" align="center">5</entry><entry>25</entry><entry>Si</entry><entry>402</entry><entry align="char" char="." charoff="28">30.9</entry><entry align="char" char="." charoff="23">12.4</entry></row><row><entry>26</entry><entry>Si</entry><entry>433</entry><entry align="char" char="." charoff="28">66.1</entry><entry align="char" char="." charoff="23">28.6</entry></row><row><entry>27</entry><entry>Si</entry><entry>410</entry><entry align="char" char="." charoff="28">75.1</entry><entry align="char" char="." charoff="23">30.8</entry></row><row><entry>28</entry><entry>Si</entry><entry>418</entry><entry align="char" char="." charoff="28">49.9</entry><entry align="char" char="." charoff="23">20.9</entry></row><row><entry>29</entry><entry>Si</entry><entry>452</entry><entry align="char" char="." charoff="28">70.8</entry><entry align="char" char="." charoff="23">32.0</entry></row><row><entry>30</entry><entry>Si</entry><entry>424</entry><entry align="char" char="." charoff="28">71.3</entry><entry align="char" char="." charoff="23">30.2</entry></row></tbody></tgroup></table></tables><tables id="tabl0019" num="0019"><table frame="all"><tgroup cols="6" rowsep="0"><colspec colnum="1" colname="col1" colwidth="20mm" /><colspec colnum="2" colname="col2" colwidth="10mm" /><colspec colnum="3" colname="col3" colwidth="10mm" /><colspec colnum="4" colname="col4" colwidth="10mm" /><colspec colnum="5" colname="col5" colwidth="10mm" /><colspec colnum="6" colname="col6" colwidth="14mm" /><thead valign="top"><row rowsep="1"><entry namest="col1" nameend="col6" align="center">ZONE 1</entry></row></thead><tbody><row><entry>Gases</entry><entry namest="col2" nameend="col6" align="left">Argon and nitrogen</entry></row><row><entry>Gas Ratio</entry><entry namest="col2" nameend="col6" align="left">80% N₂; 20% Ar</entry></row><row><entry>Gas Flows</entry><entry namest="col2" nameend="col6" align="left">1448 N₂, 365 Ar</entry></row><row><entry>Throttles</entry><entry namest="col2" nameend="col6" align="left">10%</entry></row><row><entry morerows="1">Flow Ratio</entry><entry>A</entry><entry>B</entry><entry>C</entry><entry>D</entry><entry>E</entry></row><row><entry>21</entry><entry>29</entry><entry>0</entry><entry>29</entry><entry>21 (%)</entry></row><row rowsep="1"><entry>Pressure</entry><entry namest="col2" nameend="col6" align="left">2.0x10^-3 Torr</entry></row></tbody></tgroup><tgroup cols="6" rowsep="0"><colspec colnum="1" colname="col1" colwidth="20mm" /><colspec colnum="2" colname="col2" colwidth="10mm" /><colspec colnum="3" colname="col3" colwidth="10mm" /><colspec colnum="4" colname="col4" colwidth="10mm" /><colspec colnum="5" colname="col5" colwidth="10mm" /><colspec colnum="6" colname="col6" colwidth="14mm" /><thead valign="top"><row rowsep="1"><entry namest="col1" nameend="col6" align="center">ZONE 2</entry></row></thead><tbody><row><entry>Gases</entry><entry namest="col2" nameend="col6" align="left">Argon and nitrogen</entry></row><row><entry>Gas Ratio</entry><entry namest="col2" nameend="col6" align="left">80% N₂; 20% Ar</entry></row><row><entry>Gas Flows</entry><entry namest="col2" nameend="col6" align="left">1856 N₂, 433 Ar</entry></row><row><entry>Throttles</entry><entry namest="col2" nameend="col6" align="left">9%</entry></row><row><entry morerows="1">Flow Ratio</entry><entry>A</entry><entry>B</entry><entry>C</entry><entry>D</entry><entry>E</entry></row><row><entry>24</entry><entry>26</entry><entry>0</entry><entry>26</entry><entry>24 (%)</entry></row><row rowsep="1"><entry>Pressure</entry><entry namest="col2" nameend="col6" align="left">2.1x10^-3 Torr</entry></row></tbody></tgroup><tgroup cols="6" rowsep="0"><colspec colnum="1" colname="col1" colwidth="20mm" /><colspec colnum="2" colname="col2" colwidth="10mm" /><colspec colnum="3" colname="col3" colwidth="10mm" /><colspec colnum="4" colname="col4" colwidth="10mm" /><colspec colnum="5" colname="col5" colwidth="10mm" /><colspec colnum="6" colname="col6" colwidth="14mm" /><thead valign="top"><row rowsep="1"><entry namest="col1" nameend="col6" align="center">ZONES 3 AND 4</entry></row></thead><tbody><row><entry>Gases</entry><entry namest="col2" nameend="col6" align="left">Argon (100%)</entry></row><row><entry>Gas Flow</entry><entry namest="col2" nameend="col6" align="left">1821 sccm Ar</entry></row><row><entry>Throttles</entry><entry namest="col2" nameend="col6" align="left">17%</entry></row><row><entry morerows="1">Flow Ratio</entry><entry>A</entry><entry>B</entry><entry>C</entry><entry>D</entry><entry>E</entry></row><row><entry>20</entry><entry>20</entry><entry>20</entry><entry>20</entry><entry>20 (%)</entry></row><row rowsep="1"><entry>Pressure</entry><entry namest="col2" nameend="col6" align="left">2.0-2.1x10^-3 Torr</entry></row></tbody></tgroup><tgroup cols="6" rowsep="0"><colspec colnum="1" colname="col1" colwidth="20mm" /><colspec colnum="2" colname="col2" colwidth="10mm" /><colspec colnum="3" colname="col3" colwidth="10mm" /><colspec colnum="4" colname="col4" colwidth="10mm" /><colspec colnum="5" colname="col5" colwidth="10mm" /><colspec colnum="6" colname="col6" colwidth="14mm" /><thead valign="top"><row rowsep="1"><entry namest="col1" nameend="col6" align="center">ZONE 5</entry></row></thead><tbody><row><entry>Gases</entry><entry namest="col2" nameend="col6" align="left">Argon and nitrogen</entry></row><row><entry>Gas Ratio</entry><entry namest="col2" nameend="col6" align="left">80% N₂; 20% Ar</entry></row><row><entry>Gas Flows</entry><entry namest="col2" nameend="col6" align="left">1421 N₂, 312 Ar</entry></row><row><entry>Throttles</entry><entry namest="col2" nameend="col6" align="left">14%</entry></row><row><entry morerows="1">Flow Ratio</entry><entry>A</entry><entry>B</entry><entry>C</entry><entry>D</entry><entry>E</entry></row><row><entry>19</entry><entry>31</entry><entry>0</entry><entry>31</entry><entry>19 (%)</entry></row><row rowsep="1"><entry>Pressure</entry><entry namest="col2" nameend="col6" align="left">2.2x10^-3 Torr</entry></row></tbody></tgroup></table></tables>

0066The resultant product was tested and the results are reported as follows: <tables id="tabl0020" num="0020"><table frame="all"><tgroup cols="4"><colspec colnum="1" colname="col1" colwidth="10mm" /><colspec colnum="2" colname="col2" colwidth="10mm" /><colspec colnum="3" colname="col3" colwidth="61mm" /><colspec colnum="4" colname="col4" colwidth="18mm" /><tbody><row><entry rowsep="0" align="center">I.</entry><entry rowsep="0" align="center">(a)</entry><entry rowsep="0">visible transmittance (Ill. C 2° observer):</entry><entry rowsep="0" /></row><row><entry rowsep="0" align="center" /><entry rowsep="0" align="center" /><entry rowsep="0">   before heat treatment</entry><entry rowsep="0">23%</entry></row><row><entry rowsep="0" align="center" /><entry rowsep="0" align="center" /><entry rowsep="0">   after heat treatment</entry><entry rowsep="0">22%</entry></row><row><entry rowsep="0" align="center" /><entry rowsep="0" align="center" /><entry rowsep="0" /><entry rowsep="0" /></row><row><entry rowsep="0" align="center" /><entry rowsep="0" align="center">(b)</entry><entry rowsep="0">reflectance:</entry><entry rowsep="0" /></row><row><entry rowsep="0" align="center" /><entry rowsep="0" align="center" /><entry rowsep="0">   before heat treatment</entry><entry rowsep="0" /></row><row><entry rowsep="0" align="center" /><entry rowsep="0" align="center" /><entry rowsep="0">    glass side:</entry><entry rowsep="0">≈15-16%</entry></row><row><entry rowsep="0" align="center" /><entry rowsep="0" align="center" /><entry rowsep="0">    film side:</entry><entry rowsep="0">≈22-24%</entry></row><row><entry rowsep="0" align="center" /><entry rowsep="0" align="center" /><entry rowsep="0">   after heat treatment</entry><entry rowsep="0" /></row><row><entry rowsep="0" align="center" /><entry rowsep="0" align="center" /><entry rowsep="0">    glass side:</entry><entry rowsep="0">≈14-15%</entry></row><row><entry rowsep="0" align="center" /><entry rowsep="0" align="center" /><entry rowsep="0">    film side:</entry><entry rowsep="0">≈17-18%</entry></row><row><entry rowsep="0" align="center" /><entry rowsep="0" align="center" /><entry rowsep="0" /><entry rowsep="0" /></row><row><entry rowsep="0" align="center" /><entry rowsep="0" align="center">(c)</entry><entry rowsep="0">emittance (E_n):</entry><entry rowsep="0" /></row><row><entry rowsep="0" align="center" /><entry rowsep="0" align="center" /><entry rowsep="0">   before heat treatment</entry><entry rowsep="0">0.50</entry></row><row><entry rowsep="0" align="center" /><entry rowsep="0" align="center" /><entry rowsep="0">   after heat treatment</entry><entry rowsep="0">0.55</entry></row><row><entry rowsep="0" align="center" /><entry rowsep="0" align="center" /><entry rowsep="0" /><entry rowsep="0" /></row><row><entry rowsep="0" align="center" /><entry rowsep="0" align="center">(d)</entry><entry rowsep="0">sheet resistance (ohms per sq.):</entry><entry rowsep="0" /></row><row><entry rowsep="0" align="center" /><entry rowsep="0" align="center" /><entry rowsep="0">   before heat treatment</entry><entry rowsep="0">60.0</entry></row><row><entry rowsep="0" align="center" /><entry rowsep="0" align="center" /><entry rowsep="0">   after heat treatment</entry><entry rowsep="0">73.5</entry></row><row><entry rowsep="0" align="center" /><entry rowsep="0" align="center" /><entry rowsep="0" /><entry rowsep="0" /></row><row><entry rowsep="0" align="center">II.</entry><entry rowsep="0" align="center" /><entry rowsep="0">Durability (mechanical) (Taber test only)</entry><entry rowsep="0" /></row><row><entry rowsep="0" align="center" /><entry rowsep="0" align="center" /><entry rowsep="0">   before heat treatment</entry><entry rowsep="0">8-9%</entry></row><row><entry rowsep="0" align="center" /><entry rowsep="0" align="center" /><entry rowsep="0">   after heat treatment</entry><entry rowsep="0">5-6%</entry></row><row><entry rowsep="0" align="center" /><entry rowsep="0" align="center" /><entry rowsep="0" /><entry rowsep="0" /></row><row><entry rowsep="0" align="center">III.</entry><entry rowsep="0" align="center" /><entry rowsep="0">Chemical resistance (boil test)</entry><entry rowsep="0" /></row><row><entry rowsep="0" align="center" /><entry rowsep="0" align="center" /><entry rowsep="0">   before heat treatment</entry><entry rowsep="0">pass</entry></row><row><entry align="center" /><entry align="center" /><entry>   after heat treatment</entry><entry>pass</entry></row></tbody></tgroup></table></tables>

EXAMPLE 26

0067A conventional Airco (Solar Products) Temescal multi-zone architectural sputter-coater of known design is used. This coater is schematically illustrated in <figref idref="f0002">Figure 7</figref>. In Coating Zones 1, 2, 4 and 5 there are employed three cathodes, each with two rotatable targets. In Coating Zone #3 there are employed three cathodes, each with one planar target. Thus the resulting targets are 1-27 (e.g. Coating Zone #1, Cathode Bay #1, Target "1") Glass substrate G, herein shown as a flat glass sheet (e.g. in the shape of a flat, yet to be bent and/or tempered part) is conveyed on a roller through the Airco sputter-coater whose zones are separated in a known fashion by walls (F) having in their lower extremity an adjustable tunnel (T). Pre-wash (W₁) and post-wash (W₂) are conventionally provided.

0068Using this equipment the layer system of <figref idref="f0001">Figure 1B</figref> was formed, wherein metal "M" is a substantially pure metallic nickel/chromium alloy (80/20% by wt. Ni:Cr). All 12 targets in Coating Zones #1 and #2 are of the same metal (e.g. silicon doped with about 5% Al) from which a silicon nitride layer was formed. In this case, Zone 1 and Zone 2 were regulated to approximately 2-3 microns (2-3x10^-3 Torr) with an 80% N₂ and 20% Argon atmosphere. As Glass G progressed through Zones #1 and #2 at the aforesaid pressure, silicon nitride was applied to the glass as layer "A" to a thickness of approximately 500Å.

0069As glass (G) progresses into Coating Zone #3, cathodes 7, 8 and 9 sputter a layer of the pure metallic nickel chrome alloy (80-20) in Argon at a pressure of 1-2 microns (1-2x10^-3 Torr). The thickness achieved was approximately 150Å.

0070Glass (G) was then moved through Coating Zone #4, which was regulated to a pressure of about 2-3 microns (2-3x10^-3 Torr) with an 80% N₂ and 20% Ar atmosphere. Cathodes 10, 11 and 12 (six metallic silicon targets) were used to apply a layer of silicon nitride. The glass was then moved through Coating Zone #5, which was also regulated to a pressure of approximately 2-3 microns (2-3x10^-3 Torr) with an 80% N₂ and 20% Ar atmosphere. To apply further silicon nitride, a total of six targets are used in this coat zone. All silicon targets were 95% Si, 5% Al, by weight. The total thickness of the overcoat layer of Si₃N₄ created in Zones 4 and 5 was approximately 300A. This then completes the heat treatable coating system.

0071The process conditions are as follows: <tables id="tabl0021" num="0021"><table frame="all"><tgroup cols="9"><colspec colnum="1" colname="col1" colwidth="13mm" /><colspec colnum="2" colname="col2" colwidth="17mm" /><colspec colnum="3" colname="col3" colwidth="15mm" /><colspec colnum="4" colname="col4" colwidth="12mm" /><colspec colnum="5" colname="col5" colwidth="24mm" /><colspec colnum="6" colname="col6" colwidth="14mm" /><colspec colnum="7" colname="col7" colwidth="20mm" /><colspec colnum="8" colname="col8" colwidth="23mm" /><colspec colnum="9" colname="col9" colwidth="31mm" /><thead><row><entry valign="top">Zone</entry><entry valign="top">Cathode</entry><entry valign="top">Target</entry><entry valign="top">KW</entry><entry valign="top">Cathode Volts</entry><entry valign="top">Amps</entry><entry valign="top">Material</entry><entry valign="top">Pressure</entry><entry valign="top">Material N₂%/Ar%</entry></row></thead><tbody><row><entry morerows="5" valign="middle">1</entry><entry>1</entry><entry>1</entry><entry>32.1</entry><entry>416</entry><entry>70.9</entry><entry>Si</entry><entry>2.1x10^-3 Torr</entry><entry>80/20</entry></row><row><entry>1</entry><entry>2</entry><entry>19.8</entry><entry>401</entry><entry>42.9</entry><entry>si</entry><entry>2.1x10^-3 Torr</entry><entry>80/20</entry></row><row><entry>2</entry><entry>3</entry><entry>21.6</entry><entry>402</entry><entry>60.0</entry><entry>Si</entry><entry>2.1x10^-3 Torr</entry><entry>80/20</entry></row><row><entry>2</entry><entry>4</entry><entry>26.9</entry><entry>400</entry><entry>60.8</entry><entry>Si</entry><entry>2.1x10^-3 Torr</entry><entry>80/20</entry></row><row><entry>3</entry><entry>(5)</entry><entry>x</entry><entry>x</entry><entry>x</entry><entry>Si</entry><entry>2.1x10^-3 Torr</entry><entry>80/20</entry></row><row><entry>3</entry><entry>(6)</entry><entry>x</entry><entry>x</entry><entry>x</entry><entry>Si</entry><entry>2.1x10^-3 Torr</entry><entry>80/20</entry></row><row><entry morerows="5" valign="middle">2</entry><entry>4</entry><entry>1</entry><entry>26.5</entry><entry>396</entry><entry>60.8</entry><entry>Si</entry><entry>2.0x10^-3 Torr</entry><entry>80/20</entry></row><row><entry>4</entry><entry>2</entry><entry>34.8</entry><entry>407</entry><entry>74.8</entry><entry>Si</entry><entry>2.0x10^-3 Torr</entry><entry>80/20</entry></row><row><entry>5</entry><entry>3</entry><entry>36.0</entry><entry>449</entry><entry>76.8</entry><entry>Si</entry><entry>2.0x10^-3 Torr</entry><entry>80/20</entry></row><row><entry>5</entry><entry>4</entry><entry>39.6</entry><entry>412</entry><entry>88.5</entry><entry>Si</entry><entry>2.0x10^-3 Torr</entry><entry>80/20</entry></row><row><entry>6</entry><entry>5</entry><entry>44.6</entry><entry>421</entry><entry>97.8</entry><entry>Si</entry><entry>2.0x10^-3 Torr</entry><entry>80/20</entry></row><row><entry>6</entry><entry>6</entry><entry>46.7</entry><entry>449</entry><entry>93.7</entry><entry>Si</entry><entry>2.0x10^-3 Torr</entry><entry>80/20</entry></row><row><entry morerows="2" valign="middle">3</entry><entry>7</entry><entry>1</entry><entry>11.1</entry><entry>436</entry><entry>25.5</entry><entry>80 Ni 20 Cr</entry><entry>1.5x10^-3 Torr</entry><entry>100% Argon</entry></row><row><entry>8</entry><entry>2</entry><entry>11.1</entry><entry>456</entry><entry>25.4</entry><entry>80 Ni 20 Cr</entry><entry>1.5x10^-3 Torr</entry><entry>100% Argon</entry></row><row><entry>9</entry><entry>3</entry><entry>10.9</entry><entry>442</entry><entry>24.8</entry><entry>80 Ni 20 Cr</entry><entry>1.5x10^-3 Torr</entry><entry>100% Argon</entry></row><row><entry morerows="5" valign="middle">4</entry><entry>10</entry><entry>1</entry><entry>18.4</entry><entry>410</entry><entry>41.0</entry><entry>Si</entry><entry>2.1x10^-3 Torr</entry><entry>80/20</entry></row><row><entry>10</entry><entry>2</entry><entry>18.2</entry><entry>410</entry><entry>40.0</entry><entry>Si</entry><entry>2.1x10^-3 Torr</entry><entry>80/20</entry></row><row><entry>11</entry><entry>3</entry><entry>17.2</entry><entry>409</entry><entry>39.5</entry><entry>Si</entry><entry>2.1x10^-3 Torr</entry><entry>80/20</entry></row><row><entry>11</entry><entry>4</entry><entry>17.8</entry><entry>411</entry><entry>39.6</entry><entry>Si</entry><entry>2.1x10^-3 Torr</entry><entry>80/20</entry></row><row><entry>12</entry><entry>5</entry><entry>18.1</entry><entry>407</entry><entry>39.5</entry><entry>Si</entry><entry>2.1x10^-3 Torr</entry><entry>80/20</entry></row><row><entry>12</entry><entry>6</entry><entry>18.4</entry><entry>403</entry><entry>40.4</entry><entry>Si</entry><entry>2.1x10^-3 Torr</entry><entry>80/20</entry></row><row><entry morerows="5" valign="middle">5</entry><entry>13</entry><entry>1</entry><entry>20.7</entry><entry>38.7</entry><entry>46.6</entry><entry>Si</entry><entry>2.2x10^-3 Torr</entry><entry>60/20</entry></row><row><entry>13</entry><entry>2</entry><entry>20.9</entry><entry>406</entry><entry>45.3</entry><entry>Si</entry><entry>2.2x10^-3 Torr</entry><entry>80/20</entry></row><row><entry>14</entry><entry>3</entry><entry>19.5</entry><entry>396</entry><entry>44.6</entry><entry>Si</entry><entry>2.2x10^-3 Torr</entry><entry>80/20</entry></row><row><entry>14</entry><entry>4</entry><entry>19.7</entry><entry>394</entry><entry>45.2</entry><entry>Si</entry><entry>2.2x10^-3 Torr</entry><entry>80/20</entry></row><row><entry>15</entry><entry>5</entry><entry>19.8</entry><entry>414</entry><entry>45.3</entry><entry>Si</entry><entry>2.2x10^-3 Torr</entry><entry>80/20</entry></row><row><entry>15</entry><entry>6</entry><entry>22.5</entry><entry>447</entry><entry>45.4</entry><entry>Si</entry><entry>2.2x10^-3 Torr</entry><entry>80/20</entry></row></tbody></tgroup></table></tables> Line Speed: 200"/mn Glass thickness and type: 3.9 mm green tint

0072The resultant optical characteristics are: <tables id="tabl0022" num="0022"><table frame="all"><tgroup cols="3" rowsep="0"><colspec colnum="1" colname="col1" colwidth="17mm" /><colspec colnum="2" colname="col2" colwidth="21mm" /><colspec colnum="3" colname="col3" colwidth="21mm" /><thead valign="top"><row rowsep="1"><entry namest="col1" nameend="col3" align="left">Optics as coated, Ill. "C", 2° obs.</entry></row></thead><tbody><row><entry>TY 22.65</entry><entry>RGY 16.02</entry><entry>RFY 22.43</entry></row><row><entry>a* -4 .53</entry><entry>a* -2.51</entry><entry>a* +1.21</entry></row><row><entry>b* -8.82</entry><entry>b* -0.45</entry><entry>b* +27.12</entry></row><row><entry namest="col1" nameend="col3" align="left">Sheet resist. = 65.3 ohms/sq.</entry></row><row rowsep="1"><entry namest="col1" nameend="col3" align="left">Normal emit. = 0.50</entry></row></tbody></tgroup><tgroup cols="3" colsep="0" rowsep="0"><colspec colnum="1" colname="col1" colwidth="17mm" /><colspec colnum="2" colname="col2" colwidth="21mm" /><colspec colnum="3" colname="col3" colwidth="21mm" /><tbody><row><entry namest="col1" nameend="col3" align="justify">*(heat treating was @ 665°C cycled for an automated time period of 16 minutes)</entry></row></tbody></tgroup></table></tables><tables id="tabl0023" num="0023"><table frame="all"><tgroup cols="3" rowsep="0"><colspec colnum="1" colname="col1" colwidth="20mm" /><colspec colnum="2" colname="col2" colwidth="22mm" /><colspec colnum="3" colname="col3" colwidth="22mm" /><thead valign="top"><row rowsep="1"><entry namest="col1" nameend="col3" align="left">Optics after heat treating*, Ill. "C", 2° obs.</entry></row></thead><tbody><row><entry>TY 23.04</entry><entry>RGY 15.37</entry><entry>RFY 23.46</entry></row><row><entry>a* -4.07</entry><entry>a* -3.52</entry><entry>a* +0.04</entry></row><row><entry>b* -7.13</entry><entry>b* +1.15</entry><entry>b* +22.15</entry></row><row><entry namest="col1" nameend="col3" align="left">Sheet resist. = 47.3 ohms/sq.</entry></row><row><entry namest="col1" nameend="col3" align="left">Normal emit. = 0.45</entry></row><row><entry>ΔT +0.39</entry><entry>ΔRG -0.65</entry><entry>ΔRF +1.03</entry></row><row><entry>ΔE 1.87</entry><entry>ΔE 1.09</entry><entry>ΔE 5.90</entry></row><row><entry namest="col1" nameend="col3" align="left">ΔSheet resist. = -18.0 ohms/sq.</entry></row><row rowsep="1"><entry namest="col1" nameend="col3" align="left">ΔNormal emit. = -0.05</entry></row></tbody></tgroup><tgroup cols="3" colsep="0" rowsep="0"><colspec colnum="1" colname="col1" colwidth="20mm" /><colspec colnum="2" colname="col2" colwidth="22mm" /><colspec colnum="3" colname="col3" colwidth="22mm" /><tbody><row><entry namest="col1" nameend="col3" align="justify">*(heat treating was @ 665°C cycled for an automated time period of 16 minutes)</entry></row></tbody></tgroup></table></tables><tables id="tabl0024" num="0024"><table frame="all"><tgroup cols="2"><colspec colnum="1" colname="col1" colwidth="54mm" /><colspec colnum="2" colname="col2" colwidth="112mm" /><thead valign="top"><row><entry namest="col1" nameend="col2" align="left">Testing</entry></row><row><entry namest="col1" nameend="col2" align="left">Chemical resistance:</entry></row></thead><tbody><row rowsep="0"><entry>As coated -</entry><entry>No change in physical properties after boiling (230°F) in 5% HCl acid for one hour</entry></row><row><entry>After heating -</entry><entry>no change in physical properties after boiling (230°F) in 5% HCl acid for one hour</entry></row></tbody></tgroup><tgroup cols="2"><colspec colnum="1" colname="col1" colwidth="54mm" /><colspec colnum="2" colname="col2" colwidth="112mm" /><thead valign="top"><row><entry namest="col1" nameend="col2" align="left">Taber abrasion test: ΔT (transmission) @ 300 cycles and 500 gram load</entry></row></thead><tbody><row rowsep="0"><entry>As coated -</entry><entry>ΔT = 8.1%</entry></row><row><entry>After heating -</entry><entry>ΔT = 6.3%</entry></row></tbody></tgroup></table></tables>

EXAMPLE 27

0073This example was formed on the equipment as described in Example 26 above. The same cathode, target gas ratios, pressures and process conditions were maintained as in Example 26 in Coating Zones #1 and #2 to achieve an undercoat of Si₃N₄ (and some aluminum nitride from dopant) of the same thickness as in Example 26. Changes were made, however, to the process conditions in Coating Zones #3, #4 and #5.

0074The gas composition in Coating Zone #3 was changed from 100% Argon to a 95% Argon, 5% oxygen atmosphere at the same pressure, and power was increased to the targets in Coating Zone #3 to give a metallic layer on glass (G) similar in thickness to that of Example 26. The layer system formed was that of <figref idref="f0001">Figure 2B</figref> where M was the same Ni/Cr alloy as used in Example 26, but here partially oxidized. The glass was passed through Coating Zones #4 and #5 where, as before, a silicon nitride layer was formed on top of the metallic, now partially oxidized layer (M/O). This topcoat of Si₃N₄ was kept somewhat thinner than in Example 26 in order to more nearly match the desirable optics of Example 26. The advantage of the coating layer system in this example over Example 26 is that the sheet resistance (and normal emittance) of the product after heat treatment actually achieved, is in the range of typical "low-E" coatings. Thus, this coating layer system has the ability to reflect more infrared energy as compared to the coating layer system in Example 26. Chemical durability is reduced only slightly compared to Example 26, but mechanical durability is improved over Example 26's already good durability.

0075The process conditions are as follows: <tables id="tabl0025" num="0025"><table frame="all"><tgroup cols="9"><colspec colnum="1" colname="col1" colwidth="13mm" /><colspec colnum="2" colname="col2" colwidth="17mm" /><colspec colnum="3" colname="col3" colwidth="15mm" /><colspec colnum="4" colname="col4" colwidth="12mm" /><colspec colnum="5" colname="col5" colwidth="24mm" /><colspec colnum="6" colname="col6" colwidth="14mm" /><colspec colnum="7" colname="col7" colwidth="20mm" /><colspec colnum="8" colname="col8" colwidth="23mm" /><colspec colnum="9" colname="col9" colwidth="31mm" /><thead><row><entry valign="top">Zone</entry><entry valign="top">Cathode</entry><entry valign="top">Target</entry><entry valign="top">KW</entry><entry valign="top">Cathode Volts</entry><entry valign="top">Ampe</entry><entry valign="top">Material</entry><entry valign="top">Pressure</entry><entry valign="top">Material N₂%/Ar%</entry></row></thead><tbody><row><entry morerows="5" valign="middle">1</entry><entry>1</entry><entry>1</entry><entry>32.4</entry><entry>424</entry><entry>70.9</entry><entry>Si</entry><entry>2.1x10^-3 Torr</entry><entry>80/20</entry></row><row><entry>1</entry><entry>2</entry><entry>20.1</entry><entry>413</entry><entry>43.0</entry><entry>Si</entry><entry>2.1x10^-3 Torr</entry><entry>80/20</entry></row><row><entry>2</entry><entry>3</entry><entry>27.7</entry><entry>409</entry><entry>60.4</entry><entry>Si</entry><entry>2.1x10^-3 Torr</entry><entry>80/20</entry></row><row><entry>2</entry><entry>4</entry><entry>27.2</entry><entry>405</entry><entry>59.7</entry><entry>Si</entry><entry>2.1x10^-3 Torr</entry><entry>80/20</entry></row><row><entry>3</entry><entry>5</entry><entry>x</entry><entry>x</entry><entry>x</entry><entry>Si</entry><entry>2.1x10^-3 Torr</entry><entry>80/20</entry></row><row><entry>3</entry><entry>6</entry><entry>x</entry><entry>x</entry><entry>x</entry><entry>Si</entry><entry>2.1x10^-3 Torr</entry><entry>80/20</entry></row><row><entry morerows="5" valign="middle">2</entry><entry>4</entry><entry>1</entry><entry>27.2</entry><entry>408</entry><entry>60.0</entry><entry>Si</entry><entry>2.0x10^-3 Torr</entry><entry>80/20</entry></row><row><entry>4</entry><entry>2</entry><entry>35.5</entry><entry>422</entry><entry>75.4</entry><entry>Si</entry><entry>2.0x10^-3 Torr</entry><entry>80/20</entry></row><row><entry>5</entry><entry>3</entry><entry>31.8</entry><entry>457</entry><entry>67.7</entry><entry>Si</entry><entry>2.0x10^-3 Torr</entry><entry>80/20</entry></row><row><entry>5</entry><entry>4</entry><entry>40.0</entry><entry>422</entry><entry>88.7</entry><entry>Si</entry><entry>2.0x10^-3 Torr</entry><entry>80/20</entry></row><row><entry>6</entry><entry>5</entry><entry>45.5</entry><entry>433</entry><entry>97.8</entry><entry>Si</entry><entry>2.0x10^-3 Torr</entry><entry>80/20</entry></row><row><entry>6</entry><entry>6</entry><entry>43.4</entry><entry>457</entry><entry>86.6</entry><entry>Si</entry><entry>2.0x10^-3 Torr</entry><entry>80/20</entry></row><row><entry morerows="2" valign="middle">3</entry><entry>7</entry><entry>1</entry><entry>18.6</entry><entry>451</entry><entry>39.9</entry><entry>80 Ni 20 Cr</entry><entry>1.5x10^-3 Torr</entry><entry>95 Oxygen 5 Ar</entry></row><row><entry>8</entry><entry>2</entry><entry>19.1</entry><entry>481</entry><entry>39.8</entry><entry>80 Ni 20 Cr</entry><entry>1.5x10^-3 Torr</entry><entry>95 oxygen 5 Ar</entry></row><row><entry>9</entry><entry>3</entry><entry>18.7</entry><entry>468</entry><entry>39.1</entry><entry>80 Ni 20 cr</entry><entry>1.5x10^-3 Torr</entry><entry>95 Oxygen 5 Ar</entry></row><row><entry morerows="5" valign="middle">4</entry><entry>10</entry><entry>1</entry><entry>12.3</entry><entry>409</entry><entry>27.7</entry><entry>Si</entry><entry>2.0x10^-3 Torr</entry><entry>80/20</entry></row><row><entry>10</entry><entry>2</entry><entry>12.1</entry><entry>409</entry><entry>26.6</entry><entry>Si</entry><entry>2.0x10^-3 Torr</entry><entry>80/20</entry></row><row><entry>11</entry><entry>3</entry><entry>11.3</entry><entry>408</entry><entry>26.1</entry><entry>Si</entry><entry>2.0x10^-3 Torr</entry><entry>80/20</entry></row><row><entry>11</entry><entry>4</entry><entry>11.8</entry><entry>410</entry><entry>26.1</entry><entry>Si</entry><entry>2.0x10^-3 Torr</entry><entry>80/20</entry></row><row><entry>12</entry><entry>5</entry><entry>12.0</entry><entry>412</entry><entry>26.4</entry><entry>Si</entry><entry>2.0x10^-3 Torr</entry><entry>80/20</entry></row><row><entry>12</entry><entry>6</entry><entry>12.3</entry><entry>404</entry><entry>27.2</entry><entry>Si</entry><entry>2.0x10^-3 Torr</entry><entry>80/20</entry></row><row><entry morerows="5" valign="middle">5</entry><entry>13</entry><entry>1</entry><entry>12.1</entry><entry>385</entry><entry>27.6</entry><entry>Si</entry><entry>2.1x10^-3 Torr</entry><entry>80/20</entry></row><row><entry>13</entry><entry>2</entry><entry>12.4</entry><entry>401</entry><entry>26.7</entry><entry>Si</entry><entry>2.1x10^-3 Torr</entry><entry>80/20</entry></row><row><entry>14</entry><entry>3</entry><entry>11.3</entry><entry>390</entry><entry>26.3</entry><entry>Si</entry><entry>2.1x10^-3 Torr</entry><entry>80/20</entry></row><row><entry>14</entry><entry>4</entry><entry>11.5</entry><entry>392</entry><entry>26.6</entry><entry>Si</entry><entry>2.1x10^-3 Torr</entry><entry>80/20</entry></row><row><entry>15</entry><entry>5</entry><entry>11.5</entry><entry>410</entry><entry>26.8</entry><entry>Si</entry><entry>2.1x10^-3 Torr</entry><entry>80/20</entry></row><row><entry>15</entry><entry>6</entry><entry>13.2</entry><entry>442</entry><entry>26.8</entry><entry>Si</entry><entry>2.1x10^-3 Torr</entry><entry>80/20</entry></row></tbody></tgroup></table></tables>

0076The optical results achieved were as follows: <tables id="tabl0026" num="0026"><table frame="all"><tgroup cols="3" rowsep="0"><colspec colnum="1" colname="col1" colwidth="17mm" /><colspec colnum="2" colname="col2" colwidth="21mm" /><colspec colnum="3" colname="col3" colwidth="21mm" /><thead valign="top"><row rowsep="1"><entry namest="col1" nameend="col3" align="left">Optics as coated, Ill. "C", 2° obs.</entry></row></thead><tbody><row><entry>TY 18.70</entry><entry>RGY 12.76</entry><entry>RFY 25.12</entry></row><row><entry>a* -5.06</entry><entry>a* -0.43</entry><entry>a* +0.40</entry></row><row><entry>b* -1.04</entry><entry>b* -4.27</entry><entry>b* +24.56</entry></row><row><entry namest="col1" nameend="col3" align="left">Sheet resist. = 104.5 ohms/sq.</entry></row><row rowsep="1"><entry namest="col1" nameend="col3" align="left">Normal emit. = 0.55</entry></row></tbody></tgroup></table></tables><tables id="tabl0027" num="0027"><table frame="all"><tgroup cols="3" rowsep="0"><colspec colnum="1" colname="col1" colwidth="20mm" /><colspec colnum="2" colname="col2" colwidth="22mm" /><colspec colnum="3" colname="col3" colwidth="22mm" /><thead valign="top"><row rowsep="1"><entry namest="col1" nameend="col3" align="left">Optics after heat treating*, Ill. "C", 2° obs.</entry></row></thead><tbody><row><entry>TY 23.59</entry><entry>RGY 10.77</entry><entry>RFY 21.61</entry></row><row><entry>a* -5.46</entry><entry>a* -0.36</entry><entry>a* +0.54</entry></row><row><entry>b* -3.47</entry><entry>b* -4.84</entry><entry>b* +26.77</entry></row><row><entry namest="col1" nameend="col3" align="left">Sheet resist. - 15.2 ohms/sq.</entry></row><row><entry namest="col1" nameend="col3" align="left">Normal emit. = 0.183</entry></row><row><entry>ΔT +4.89</entry><entry>ΔRG -1.99</entry><entry>ΔRF -3.51</entry></row><row><entry>ΔE 6.03</entry><entry>ΔE 3.45</entry><entry>ΔE 4.74</entry></row><row><entry namest="col1" nameend="col3" align="left">ΔSheet resist. = -89.3 ohms/sq.</entry></row><row rowsep="1"><entry namest="col1" nameend="col3" align="left">ΔNormal emit. = -0.37</entry></row></tbody></tgroup></table></tables><tables id="tabl0028" num="0028"><table frame="all"><tgroup cols="2"><colspec colnum="1" colname="col1" colwidth="54mm" /><colspec colnum="2" colname="col2" colwidth="112mm" /><thead valign="top"><row><entry namest="col1" nameend="col2" align="left">Testing</entry></row><row><entry namest="col1" nameend="col2" align="left">Chemical resistance:</entry></row></thead><tbody><row rowsep="0"><entry>As coated -</entry><entry>slight change in /physical properties after boiling (230°F) in 5% HCl acid for one hour</entry></row><row><entry>After heating -</entry><entry>slight change in physical properties after boiling (230°F) in 5% HCl acid for one hour</entry></row></tbody></tgroup><tgroup cols="2"><colspec colnum="1" colname="col1" colwidth="54mm" /><colspec colnum="2" colname="col2" colwidth="112mm" /><thead valign="top"><row><entry namest="col1" nameend="col2" align="left">Taber abrasion test: ΔT (transmission) @ 300 cycles and 500 gram load</entry></row></thead><tbody><row rowsep="0"><entry>As coated -</entry><entry>ΔT = 3.1%</entry></row><row><entry>After heating -</entry><entry>ΔT = 1.8%</entry></row></tbody></tgroup></table></tables>