Adaptable, durable, heat treatable, ir radiation reflecting glass coated by ion sputtering and method of making same

The present invention relates to a glass article having a sputter coated glass substrate in a layered system and then heat treated. This product is stable after heat treatment and shows no substantial change in appearance as a result of and during heat treatment.

Metal and metal oxide coated glasses for architectural and automotive applications are well known. According to information contained in numerous patents, as well as in the general literature, such glasses, by selecting the layer system of the coating, can obtain acceptable reflectance, transmittance, emissivity, chemical resistance and durability, as well as the desired color. In this regard, for example, U.S. Patent Nos. 3,935,351, 4,413,877, 4,462,883, 3,826,728, 3,681,042, 3,798,146 and 4,594,137 mention several such glasses.

The popularity of coated glasses has resulted in numerous efforts to obtain coated glass articles which are coated prior to heat treatment and then heat treated without adversely altering the characteristics of the coating or glass as such (i.e., the resulting glass product). It is particularly difficult to obtain a uniform coating on previously bent glass. It is known that to obtain a uniform coating it is a much simpler technique to coat a flat glass surface and then bend it than to coat a previously bent glass. It is also true that, for example, in architectural and residential glass, where both toughened and non-toughened glass sheets are used in the same building, they must fit together as closely as possible, at least in terms of their appearance

183 571 of the glass side, as well as color and reflectivity - the characteristics best expressed by ΔΕ as defined in ASTM Designation D-2244-93 (published November 1993) under the title Standard Tests Method for Calculation of Color Diffemces from Instrumentally Measured Color Coordinates. That is, the lower ΔΕ, the closer and more accurate the match.

Certain techniques have been developed in the past to manufacture heat treatable coated glass articles which may then be heat treated to be toughened, bent or subjected to a technique known as heat strengthening. Many of these pre-coated articles had some drawbacks in that they were not heat treatable at the higher temperatures necessary to economically bend, temper, and / or cure (e.g. 620 ° C - 790 ° C). A disadvantage of such techniques was the need to maintain the temperature at approximately 590 ° C or less in order to achieve heat treatability without adversely affecting the coating or its substrate. In almost all of the previous known techniques, the substrate coated with such an arrangement did not actually fit together after being heat treated, even when considered heat treatable, as manifested, for example, by an excessively high value of ΔΕ at least in the reflectance characteristics on its glass side.

The absence of any adverse changes to the coating or its substrate is defined by the term heat treatable as used herein. While in many situations some characteristics may vary slightly during heat treatment, being heat treatable as used herein means that desirable properties such as emissivity, sheet resistance, durability and chemical resistance of the final layer system and end product must be achieved despite the fact that that the coated glass has undergone one or more of the above-mentioned heat treatments (i.e., bending, toughening and / or heat strengthening). For most of the architectural features considered here, optimal heat treatability means that the glass and its layered coating remain unchanged, at least in terms of their properties such as emissivity, sheet resistance, durability and chemical resistance, for the product heat-treated to the final product. after heat treatment. For most automotive as well as architectural purposes, the change in emissivity for the better (i.e. lowering it) due to fattening can be tolerated and is even desirable, as long as optimal heat treatability means that the change occurs uniformly across the substrate and is independent of the parameters used. for heat treatment.

In the practice of this invention, the coating system is preferably heat treatable in the sense of the term explained above, but it is equally important that a product so coated with the heat-treated coating system is also compatible with a similar product that has not been heat treated ( i.e. to itself before heat treatment), because its ΔΕ, as a characteristic of the coating system, at least with regard to glass side reflectance, it has been minimized (i.e., due to the uniqueness of certain coating systems according to the invention).

In this regard, U.S. Patent 5,188,887 discloses certain coating systems known in the art that are heat treatable as they can be successfully heat treated at the higher temperatures noted above to achieve the desired result despite having gone through quenching, bending. or heat strengthening. Generally speaking, known coating compositions distinguish among the coating systems one that employs a high nickel alloy as the metal layer, which in a preferred embodiment is an alloy known as Haynes 214 containing essentially 75.45% Ni, 4.00% Fe, 16, 00% Cr, 0.04% Al and 0.01% Y (in wt%). By using a high nickel alloy such as Haynes 214 and coating it with stoichiometric tin oxide (SnO2) either alone or with other layers (such as a backcoat of the same stoichiometric tin oxide and / or an intermediate aluminum layer between the top layer SnO2 and a high nickel alloy), it was found that the heat workability of glassware at elevated temperatures from about 620 ° C

183 571 to 790 ° F, for approximately 2-30 minutes, can be achieved without degradation in color, mechanical durability, emissivity, reflectance, or transmittance. Thus, these compositions established significant advances over previous heat treatable systems such as those disclosed in the following US Patents 4,790,822, 4,816,034, 4,826,525, 4,715,879, and 4,857,094. However, such coating systems have been found to be mismatched in view of the definition of the term given above, as illustrated by their rather high ∆Ε values ​​after heat treatment.

In addition to the above patents, a Leybold TCC-2000 glass system for vehicle windshields is also known. This system uses four or five layers of metals or metal oxides to produce sputter-coated glass which, being somewhat heat treatable at temperatures up to 590 ° C, can be used as pre-coated glass for curved or unbent glass vehicle windscreens, provided that the heat treatment is carried out rapidly within prescribed time limits. Layering outwardly from the glass substrate typically includes a first tin oxide layer, a second nickel / chromium alloy layer (typically about 80/20), a third silver layer, a fourth nickel / chromium alloy layer, and a fifth tin oxide layer. In addition to the rather low upper limit for temperature and heat treatment times, the resulting coatings are rather soft and exhibit unacceptably low chemical resistance characteristics, so that in fact they can only be applied to the interior surfaces of laminated vehicle glass windscreens. Matchability is not available in these systems.

In the aforementioned US Patent 4,715,879, it is particularly emphasized that such a coating system cannot be obtained unless a protective metal oxide layer (i.e., tin oxide) is formed such that the oxide is deficient in oxygen (i.e., not stoichiometric). . This of course requires careful balancing during the manufacturing process. Thermal workability is also described in US Patent 4,826,525. However, it is particularly emphasized in this specification that an aluminum layer must be used in order to obtain heat workability. However, no match was achieved in any case.

The aforementioned US Patent 5,229,194 discloses a significant advance in heat treatable sputter coatings, even over those disclosed in US Patent 5,188,887. This specification states that unique results can be obtained in the field of heat treatable sputter coated glasses, especially for use as privacy windows in vehicles, if a layer of metallic nickel or a high metallic nickel alloy layer is surrounded by a primer and a cover coating. with a separate layer of nickel oxide or nitride or a high nickel alloy and further coated with an oxide coating such as SnO₂, ZnO, TiO2, or an oxide of the alloys used herein. Silicon is also mentioned as being useful for use in a first coating covering a layer containing metallic nickel.

These coating systems in their preferred forms have shown particularly good heat treatability and abrasion resistance. While some of them were initially found to be chemically resistant, these systems, when they began to be mass produced, were found to fail the rigorous chemical resistance test using 5% HCl boiling hydrochloric acid (discussed below). However, their IR and UV reflectance characteristics were found to be excellent for a wide range of applications. Moreover, their visible light transmittance values, while desirable for use in privacy windows, have turned out to be too low to be really useful for use on glass windows or panels for architectural or residential purposes where high visible light transmittance is required. Thus, when the production of sputter coatings was required to fulfill orders for architectural and residential coated glass, after the glass sheets for privacy windows had already been coated, the coating equipment had to be turned off in order for the new layering system to be created. If it could

183 If this exclusion is avoided, significant economic benefits could be obtained. Still, a lack of match was found.

US Patent 5,344,718 discloses a particularly unique sputter-coated layer system which has remarkable suitability for architectural and residential purposes by obtaining not only good chemical and mechanical durability but also solar management properties. Such systems are properly considered low E glasses (coatings) because their hemispherical emissivity (Eh) was generally less than about 0.12. When measured otherwise, their sheet resistance was preferably less than about 10.5 ohms / square. In addition, for normal glass thickness (i.e. 2mm - 6mm), the visible transmittance was preferably about 78% or more (compared to less than 22-23% for the particularly preferred embodiments of the above-mentioned heat treatable laminate systems for windows providing privacy).

The solution of the aforementioned US Patent 5,344,718 achieves uniquely low E values, high visible light transmittance values, together with good chemical stability and abrasion resistance, thanks to the use of a layered system which essentially comprises (from the glass towards the outside) a backing a layer S13N4, a first layer of nickel or a nickel alloy, a silver layer, a second layer of nickel or a nickel alloy, and a top coat of the layer S13N4. In a particularly preferred embodiment, the layer system away from the glass outwards consists of:

Si₃N4 / Ńi: Cr / Ag / Ni: Cr / Ag / Ni: Cr / Si₃N₄

It has been found that this seven layer system exhibits somewhat better durability and scratch resistance properties than the above described five layer system. However, in each system, the preferred Ni: Cr layer was nichrome, with a Ni: Cr weight ratio of 80/20 wherein the major part of the chromium is in the form of chromium nitride, since the Ni: Cr layer was formed in a nitrogen-containing atmosphere.

Unfortunately, stable, low E and high visible light transmittance glass layers have proved to be heat-treatable and non-compatible. It has recently been discovered that this was not due to the oxidation of the silver layer (s), but the reason for this was that the metallic silver layer (s) lost their continuity during heat treatment due to lack of wetting; in this case, the surrounding Ni: Cr layers are insufficient to maintain the continuity of the silver layer (s) during heat treatment. Thus, these multi-layer systems with the remaining advantages could not be used where the laminated glass was to be subsequently heat-treated, e.g. by hardening, heat strengthening and bending. Unfortunately, the use of silver layers was necessary in order to obtain the E-values ​​at desirable low levels.

It must be remembered that heat treatable sputter coatings have found their application not only in the windshield technology. Also, specific architectural and residential applications require the coated glass to be toughened, bent or heat strengthened. Moreover, the low E systems of cited US Patent 5,344,718 could not be adapted to obtain low enough visible transmittance values ​​to make them suitable for privacy windows, even if they were heat treatable ... although they were not .

U.S. Patent 5,376,455 discloses particular low E heat treatable coating systems. These systems include towards the glass outward, a first layer S13Ń4 (350 A-450 A average), a first nickel or nichrome layer (20 A average), a silver layer (50 A -120 A average), a second nickel or nichrome layer ( 7 A average), the second layer S13Ń4 (450 A -550 A average). While a match between heat treated and non-heat treated systems is achieved, this is only achieved by matching two different layer systems (e.g. column 23 line 68 - column 24 line 21). Thus, despite considerable progress, it has not been possible to provide a single layer system which, while being heat treatable, would also have at least a sufficiently low degree of glass side reflection ΔΕ to be considered matchable.

183 571 after heat treatment with itself (e.g., the same coating system applied simultaneously to the same batch with the substrate or later to a different batch) prior to heat treatment.

As can be seen from the above, if one skilled in the art would like to continue to obtain the known benefits of abrasion and corrosion resistance (i.e. chemical resistance) through the use of S13N4 layers, but also would like to avoid production downtime or the need to create a different layering system for matchability while at the same time. obtaining heat treatability, the skilled person would encounter insoluble problems.

It is apparent from the prior art that there is a need for a layered system that employs sputter coating while avoiding the above-described technical problems and drawbacks of the known systems.

According to the invention, a glass article comprising a glass substrate having a sputter coated layering on top and then heat treated has, away from the glass substrate:

a) a base layer containing silicon nitride,

b) a metallic layer that comprises nickel or a nickel alloy with a nickel content of at least 10% by weight substantially free of nitride or oxide; and

c) a cover layer comprising silicon nitride, wherein the heat treated glass article exhibits a glass side reflectance Δ nieη of no greater than about 2.0 with a glass substrate thickness of about 1.5mm -13mm.

Said glass product has a silver-free layering. Preferably, layer (a) is about 5-70 A thick, layer (b) is about 30-150 A thick, layer (c) is about 200-500 A thick. The layered glass product after heat treatment has a reflectance ΔΕη on the coating side Not greater than about 5.0, visible light transmittance ΔΕη not greater than about 5.0, and has both before and after heat treatment the following characteristics:

YOU, approximately 1% - 80%

RqY, about 4% - 55%

R_fY, approximately 4% - 65%

E._n, about 0.1 - 0.75

They are about 0.1-0.75

R_s, about 20 - 500 ohms / sq.

It is also preferred that layer (a) has a thickness of about 30-50 Å, layer (b) has a thickness of around 50-100 Å, layer (c) has a thickness of around 300-400 Å, the glass product having both in front of and after heat treatment, the following characteristics:

<td>YOU,</td><td>less than 70%</td>

<td>RgY,</td><td>about 5% - 45%</td>

<td>RfY,</td><td>about 5% - 45%</td>

<td>visible color,</td><td>ah about 0 ± 2</td>

<td></td><td>bh about -4 ± 4</td>

<td>E._n,</td><td>about 0.2 - 0.75</td>

<td>Eh,</td><td>about 0.2 - 0.75</td>

<td>R_s,</td><td>about 20-300 ohms / sq.</td>

The glass product according to the invention is durable and chemically resistant and is hardened during heat treatment.

Also preferably, layer (a) has a thickness of about 40 Å, layer (b) has a thickness of around 75 Å, and contains unnitrided and non-oxidized nichrome with a nickel to chromium weight ratio of about 80:20, and layer (c) has a thickness of about 350 A, wherein said glass article exhibits both before and after heat treatment the following characteristics:

<td>TY, RgY, RfY,</td><td>about 50% about 13% about 10% - 11%</td>

183 571 glass side reflectance ΔΕη less than about 1.5, reflectance ΔΕ_η at the coating side of less than about 4.0, and visible transmittance ΔΕη less than about 4.0.

In preferred glass articles that are durable and chemically resistant, the glass side reflectance ΔΕη is less than about 0.5, the coating side reflectance ΔΕη is less than about 2.0, visible light transmittance ΔΕη is less than about 1.0 . Preferably, layer (a) has a thickness of about 40 Å, layer (b) has a thickness of around 140 Å and contains unnitrided and unoxidized nichrome with a nickel to chromium weight ratio of about 80:20, and layer (c) has a thickness of about 350 A, wherein said glass article shows both before and after toughening the following characteristics:

YOU, around 30%

Rg Y, about 20-21%

R_fY, about 16% glass side reflectance ΔΕη less than about 2.0, reflectance

Coating side ∆Εη less than about 4.0, visible light transmittance ∆Εη less than about 3.0, wherein said glass article is durable and chemically resistant. The silicon nitride layers preferably contain up to about 6% by weight of aluminum, said layer system being silver free and comprising said layers (a), (b) and (c), the layer system being stable and chemically resistant.

In order to correctly determine the match achieved by the present invention, the set of different characteristics given below were measured using a transparent glass substrate (to demonstrate that the matchability is achieved by the layering and not as a result of the substrate used). Typical characteristics achieved by the unique coating systems of the invention are as follows:

<td>Characteristic</td><td>Range</td><td>Favorable range</td>

<td>Visible Light Transmission (YOU):</td><td>about 1% - 80%</td><td>Less than about 70%</td>

<td>Visible Light Reflectance (RqY) (glass side):</td><td>about 4% - 55%</td><td>About 5% - 45%</td>

<td>Visible Light Reflectance (RgY) (Coating Side):</td><td>about 4% - 65%</td><td>About 5% - 45%</td>

<td>Visible color (glass side):</td><td>silver, tin-lead alloy, blue, gray</td><td>About ah, 0 ± 2 bh, -4 ± 4</td>

<td>Emissivity (normal, i.e. E_n &amp; hemisphere, E_h)</td><td>about 0.10-0.75</td><td>About 0.2 - 0.75</td>

<td>Sheet resistance (R._s):</td><td>approximately 20 - 500 ohms / square</td><td>Approximately 20 - 300 ohms / square</td>

<td>Solar light transmission (T_s):</td><td>about 1% - 80%</td><td>Less than about 70%</td>

<td>ΔΕ_η glass side reflectance</td><td>about &lt;2.0</td><td>Less than about 1.5</td>

<td>ΔΕ_η coating side reflectance</td><td>about &lt;5.0</td><td>Less than about 4.0</td>

<td>ΔΕ_η visible light transmission</td><td> &lt;5,0</td><td> &lt;4,0</td>

In the most preferred embodiments of the invention, the final product and its layering system, both before and after heat treatment, exhibit excellent chemical resistance and durability (i.e., abrasion and scratch resistance).

The subject of the invention in an exemplary embodiment is illustrated in the drawing which shows a partial cross-section through a coating system on a glass substrate.

183 571

Specific terms are commonly used in the glass coating art, especially when specifying the properties and solar management characteristics of coated glass used in architecture and / or automotive engineering. Such terms are used according to their well-known meanings. For example: the light intensity of visible wavelengths, the reflectance is given by its% value and is denoted as RxY (i.e. the value of Y is given below in ASTM 308-85), where X is either G for the glass side or F for the side of the applied layers. The glass side (i.e., G) is viewed from the side of the glass substrate opposite to the side where the coating is located, while the side of the coated (i.e., F) means is viewed from the side of the glass substrate where the coating is located. .

Color characteristics are measured using a and b coordinates. These coordinates are indicated by the index h to denote the conventional application of the Hunter method (or Hunter units) of Illuminant C, 10 ° observer, according to ASTM D-2244-93 Standard Test Mathod for Calculation of Color Differences From Instrumentally Measured Color Coordinates 9/15/93 extended with ASTM E-308-85, Annual Book of ASTM Standards, Volume 06.01 Standard Methid for Computing the Colors of Objects by Using the CIE System.

The terms' emissivity and transmittance are well known in the art and are used herein according to their known meanings. Thus, for example, the term transmittance herein means solar transmittance, which is supplemented by visible light transmittance (TY), infrared energy transmittance, and ultraviolet energy transmittance, the total solar energy transmittance (TS) is thus usually characterized as the average of these other values. Regarding these transmittances, visible transmittance as reported herein is characterized by standard Illuminanta C technique at 380-720 nm, for infrared it is 800-2,100 nm, for ultraviolet it is 300-400 nm; and the total solar transmittance is 300 - 2100 nm. However, for the purposes of emissivity, as discussed below, a specific infrared range (i.e., 2,500,400,000 nm) has been used.

Visible transmittance can be measured using known, conventional techniques. For example, a spectral transmittance curve is obtained by using a spectrophotometer such as a Beckman 5240 (Beckman Sci. Inst. Corp.). Thus, visible transmittance is calculated using the above-mentioned ASTM 308 / 2244-93 methodology. If necessary, fewer wavelength points than recommended can be used. Another technique for measuring visible transmittance is to use a spectrometer such as the commercially available Spectragard Spectrophotometer manufactured by Pacific Scientific Corporation. This device measures and communicates directly visible transmittance. As shown, visible transmittance (ie, Y value in CIE trichromatic values, ASTM E-308-85) uses Illuminant C., 10 ° observer.

The emissivity (E) is a measure or characteristic of both the absorption and the reflectance of light at given wavelengths. Usually it is represented by the formula:

Ε = 1 - Reflectance coefficient fi

For architectural purposes, the emissivity values ​​become very important in the so-called mid-range infrared spectrum, sometimes also called far-range, i.e. around 2,500 - 40,000 nm, for example, as determined with WINDOW 4.1, LBL-35298 (1994 ) by Barkeley Laboratories as quoted below. The term emissivity as used herein is used to refer to the emissivity values ​​measured in this infrared range as defined by the 1991 Proposed ASTM Standard for measuring infrared energy to calculate emissivity as proposed by the Primary Glass Manufacturers' Council and entitled Test Method for Maesuring and Calculating Emittance of Architectural Fiat Glass Products Using Radiometrie Measurements. In this standard, the emissivity is defined as the hemispherical emissivity (Eh) and the normal emissivity (E_n).

The current collection of measurement data of such emissivity values ​​is traditional and can be done by using, for example, the Beckman Model spectrophotometer

183 571

4260 with UV equipment (Beckman Scientific Inst. Corp.). This spectrophotometer measures the reflectance as a function of wavelength, and hence the emissivity is calculated using the above-mentioned 1991 Proposed ASTM Standard, which was incorporated herein by reference.

Another term used is sheet resistance. Sheet resistance (R._s) is a term known in the art and is used herein according to its meaning. This term relates to the resistance of a layer system on a glass substrate to the electric current passing through the layer system and is expressed in ohms per square. Sheet resistivity is an indicator of how well a layer reflects infrared energy, and is therefore often used together with emissivity as a measure of its performance. Sheet resistance is conventionally measured using a 4-point probe ohmmeter, such as a 4-point dispersible resistive probe with an Instruments Corp. Magnetron Head, Model M-800 manufactured by Signatone Corp., Santa Clara, California.

Chemical or chemically stable are used herein as synonyms of terms used in the art: chemical resistance or chemical stability. Chemical durability is determined by boiling a sample of a 2 x 5 (5 cm x 7.5 cm) coated glass substrate in approximately 500 cm.³ 5% HCl for 1 hour (i.e. at about 105 ° C). A sample is considered to pass this test (and therefore is chemically resistant or considered to be chemically stable) when, after this 1 hour of cooking, the layered sample exhibits no pores greater than about 0.076 mm in diameter.

The term mechanical durability, or simply durability, is determined using one of two tests. The first test is used by the Pacific Scientific Abrasion Tester (or its equivalent) in which a nylon brush of approximately 5 x 10 x 2.5 cm is cycled through the layering for 500 cycles using a 150 g mass applied to a sample of approximately 15 x 43 cm. In another alternative test, a conventional Taber abrasive machine (or equivalent) is used by subjecting a 10 x 10 cm sample to 300 revolutions of two CS 10F abrasive wheels having an attached mass of 500 g each. In both of these tests, the test is considered passed and the product is considered durable when no particularly noticeable scratches appear when viewed with the naked eye in visible light.

The discussed thicknesses of the various layers in these systems are measured and the term thickness as used herein is determined by alternative techniques. One technique uses known optical curves, or, in an alternative technique, a conventional needle ellipsometer (ie, profilometer) is used. In another particularly preferred technique, a n &amp; k analyzer (n &amp; k Technology, Inc., Santa Clara, California) is used. This technique is described in US Patent 4,905,170, along with the possibility to determine the values ​​of n (i.e. refractive index) and k (i.e. extinction coefficient) of the test coating.

Another term as used herein and one of the most important terms in understanding the subject matter of the invention is delta E (ie ∆Ε). The term is known in the art, and is referenced herein, along with various techniques for defining it, in the above-mentioned ASTM-2244-93.

ΔΕ in accordance with ASTM-2244-93 is an appropriate way of expressing the change (or lack thereof) in reflectance and / or transmittance (and therefore also color appearance) in an article. ΔΕ is determined by the ab technique, by the Hunter (H) technique, and / or by the Friele-MacAdam-Chickering (FMC-2) technique. They are all found suitable for the purposes of the present invention. As used herein, ΔΕ is determined by the Hunter technique and is denoted by the symbol ΔΕη- Thus, for example, when the glass side reflectance ΔΕη of a coated substrate is said to be not greater than about 2.0, the value 2.0 is the value according to Hunter.

Equivalent values ​​are within the scope of the present invention when determined by one of the other two techniques (ab or FMC-2) discussed in ASTM2244-93 or another technique designed to calculate such variation or absence.

For most commercial purposes, for proper matchability, the glass side reflectance characteristics must be as low as possible for ΔΕ,

183 571 and ΔΕ for the coating side reflectance and / or transmittance are for most, but not all, applications either unimportant or much less important. Nevertheless, the invention contemplates matching when the latter two values ​​of ΔΕ are not taken into account that the coating side reflectance ΔΕ as well as visible transmittance ΔΕη should be less than or equal to about 5.0, and preferably less than or equal to about 4.0. These, of course, are Hunter values, and therefore also the equivalence of values ​​obtained by other techniques applies to them.

Figure 1 of the accompanying drawing shows a partial cross sectional view of a typical embodiment of the product according to the invention. The glass substrate 1 has a primer coat 2 (i.e., layer 1 - first) S13N4 thereon, an intermediate layer 3 (i.e., layer 2 - the second) of unnitrogenated nickel or nickel alloy (preferably 80/20 nichrome) and a cover coat 4 (i.e., layer 2 - second). 4 - the third). The layers as taite are herein referred to as layer 1, 2 and 3, respectively.

Layer formation on the glass substrate 1 may be accomplished by conventional multi-member (multi-disk) sputter coating systems as manufactured by Airco, Inc. An example of a useful coater is the G-49 Airco Inc. for ion sputtering on large flat glass. It should be noted that an important aspect of the present invention is that unique results are achieved using conventional sputter coating techniques without the need for special processes to alleviate internal stresses discussed in US Patent 5,377,045.

As shown in the figure, only three layers are used in the embodiment of the invention, i.e. 1, 2 and 3. From the glass towards the outside, both the general and the preferred range of layer thicknesses were measured by the n &amp; k technique for this particular embodiment are they are as follows:

<td>Layer</td><td>Ingredient</td><td>Thickness (A)</td><td>Preferred thickness (A)</td>

<td> 1</td><td>S13N4 *</td><td>about 5-70</td><td>about 30-50</td>

<td> 2</td><td>Ni or nichrome **</td><td>around 30-150</td><td>about 50-100</td>

<td> 3</td><td>Si₃N₄ *</td><td>about 200-500</td><td>about 300-400</td>

* ultimately may be added up to about 6% by weight of aluminum and / or stainless steel (e.g. ss # 316).

** preferably nichrome is used (e.g. with a Ni / Cr weight ratio of 80/20)

It is a feature of the present invention that the prior belief that a nickel alloy with a high nickel content (or pure nickel) is required for heat workability is not confirmed when used in combination with S13N4 layers as stated above. While layer 2 should be a nickel inclusive layer, it need not be a nickel high nickel alloy. However, a requirement of the invention is that while some greater or lesser amount of oxidation could be tolerated in the nickel-containing layer, the nickel-containing layer must remain free of any nitrides in order to be sufficiently chemically resistant. However, for optimal matchability it is important not to allow oxidation of the nickel layer or the nickel alloy to take place.

In this regard, while the nitrides do not interfere with the heat workability in most cases, it has been found that the formation of the nitride reduces the chemical resistance as determined by the 5% HCl boil test described above.

As stated above, the nickel inclusive layer may be formed of nickel alone, but a simple Ni / Cr alloy is more preferred. An example of a group of alloys that can be used are many stainless steels with a nickel content as low as about 10% by weight (for example, SS-316 which contains 10% Ni and 90% mainly Fe and Cr). Obviously, nickel / chromium alloys with high nickel remain most preferred for the invention. This includes Ni / Cr alloy 80/20 by weight and Haynes 214 alloy whose nominal weight composition includes:

183 571

Element:

Ni Fe Cr C Al Y (Average) wt%:

75,45

4,00

16,00

0,04

4,50

0,01

Other examples of Ni / Cr alloys useful in the practice of the present invention include inconel and nichrome. Thus, generally speaking, the metal layer used in conjunction with the surrounding S13N4 layers comprises at least about 10 wt% nickel, and must be present in an unoxidized (or only slightly oxidized) form and preferably nitride free to increase chemical resistance.

While the drawing shows the triple layer system, if required, other layers may be added to achieve further objects and characteristics, however, such other layers should not adversely affect the match characteristics unique to this invention.

EXAMPLES

The layer systems listed below were sputter coated with a G-49 Airco Coater for Large Area Flat Glass onto clear glass substrates 6.35mm thick and 2.54 x 3.66m wide and long using the target layer with Si doped with about 6% by weight of aluminum and traditional sputter coating techniques. The chemical resistance and durability tests described above were applied. The heat treatment applied was a repetition of the traditional hardening process using an industrial quench furnace in which the sample was exposed to a temperature of up to about 685 ° C for an average of 3 minutes cycles (actual sample temperature of approximately 649 ° C) and then cooled rapidly to room temperature. Plates measuring 61 x 91.5 cm were cut from the samples prior to quenching. The coating layer thickness was measured using the n &amp; k technique.

Example 1 (reference numerals apply to the drawing)

Using a conventional coating apparatus and the equipment set below, a first primer coat 2 [layer 1 - first] of S13Ń4 with a thickness of approximately 40A was applied to a transparent glass substrate. chromium equal to 80/20) [i.e. layer 2 - second] approximately 75 A thick. Finally, a top coat 3 [layer 3] of S13N4 approximately 350 A was applied.

The coated samples thus produced passed the above-described mechanical stability and chemical resistance tests, both before and after the heat treatment. Their solar management properties and Hunter ΔΕ values ​​(and Hunter color coordinates ah and bh) are summarized below. Briefly, the coated article proved to be durable, capable of being hardened, bent, and did not significantly change its appearance as a result of the tempering heat treatment to which it was subjected. Therefore, it has been found to be fit under conditions of industrial acceptability, and to have highly desirable solar management properties, in single-glazed or multi-glazed IG architectural products.

183 571

COATING MACHINE SETTINGS

<td>layer</td><td>Material</td><td>% n₂</td><td>% Ar</td><td>pressure (track)</td><td>cathode power</td><td>cathode voltage</td><td>cathode amps</td><td>linear speed</td><td>number of passes</td>

<td> 1</td><td>silicon</td><td> 80</td><td> 20</td><td>2.0x10 '³</td><td>27.7 kW</td><td>414V</td><td>66.9A</td><td> 334</td><td> 1</td>

<td> 2</td><td>nichorm</td><td> 0</td><td> 100</td><td>2.0x10 '³</td><td>18.1 kW</td><td>429V</td><td>42.1A</td><td> 334</td><td> 1</td>

<td> 3</td><td>silicon</td><td> 80</td><td> 20</td><td>2.0x10 '³</td><td>334.9 kW</td><td>462V</td><td>724.9A</td><td> 334</td><td> 1</td>

OPTICAL PROPERTIES (111 ° C, 10 ° observer, Hunter values)

<td>PROPERTY</td><td>Y</td><td>3h</td><td>bh</td>

<td>glass side reflectance (not heated)</td><td> 12,93</td><td> -1,1</td><td> -8,1</td>

<td>glass side reflectance (heated)</td><td> 12,75</td><td> -1,12</td><td> -7,75</td>

<td>ΔΕ</td><td> 0,44</td><td></td><td></td>

<td>layer side reflectance (not heated)</td><td> 9,79</td><td> 1,53</td><td> 4,05</td>

<td>layer side reflectance (heated)</td><td> 10,67</td><td> 1,15</td><td> 3,34</td>

<td>ΔΕ</td><td> 1,6</td><td></td><td></td>

<td>transmittance (not heated)</td><td> 51,85</td><td> -2</td><td> -2,59</td>

<td>transmittance (heated)</td><td> 52,99</td><td> -1,93</td><td> -2,29</td>

<td>ΔΕ</td><td> 0,84</td><td></td><td></td>

Before heat treatment, the emissivity normal (E_n) and hemispherical (Eh) were 0.73 and 0.69 respectively, and the sheet resistance (R_s) was 260 ohms / square. After heat treatment E_n and Eh were 0.71 and 0.67, respectively, and R_s was 235 ohms / square (i.e. each of these values ​​showed little change as defined by heat treatability).

Example 2

The procedure of Example 1 was repeated, except that the thickness of the intermediate nichrome coating [i.e. of layer 2] to about 140 A (i.e., doubled on average) to reduce visible light transmittance to the true privacy window range (e.g., to about 30% glass side transmittance for visible light). The tables below list the coater settings and properties, respectively. Again, the coated article proved to be conformable under conditions of industrial acceptability, durable, toughened, bentable, and showed no appreciable change in its appearance due to heat treatment. It also exhibited desirable sunlight management properties, especially when low visible light transmittance was required for privacy.

COATING MACHINE SETTINGS

<td>layer</td><td>Material</td><td>% n₂</td><td>% Ar</td><td>pressure (track)</td><td>cathode power</td><td>cathode voltage</td><td>cathode amps</td><td>linear speed</td><td>number of passes</td>

<td> 1</td><td>silicon</td><td> 80</td><td> 20</td><td>2.0x10 '³</td><td>28.2 kW</td><td>414V</td><td>68.1A</td><td> 334</td><td> 1</td>

<td> 2</td><td>nichorm</td><td> 0</td><td> 100</td><td>2.0x10 '³</td><td>39.3 kW</td><td>454V</td><td>86.6A</td><td> 334</td><td> 1</td>

<td> 3</td><td>silicon</td><td> 80</td><td> 20</td><td>2.0x10 '³</td><td>334.9 kW</td><td>462V</td><td>724.9A</td><td> 334</td><td> 1</td>

183 571

OPTICAL PROPERTIES (111 ° C, 10 ° observer, Hunter values)

<td>PROPERTY</td><td>Y</td><td>and_h</td><td>b_h</td>

<td>glass side reflectance (not heated)</td><td> 20,6</td><td> 0,9</td><td> -3,59</td>

<td>glass side reflectance (heated)</td><td> 19,5</td><td> -1,22</td><td> -5,03</td>

<td>ΔΕ</td><td>Ł9</td><td></td><td></td>

<td>layer side reflectance (not heated)</td><td> 15,6</td><td> 2,45</td><td> 14,31</td>

<td>layer side reflectance (heated)</td><td> 16,4</td><td> 1,47</td><td> 10,43</td>

<td>ΔΕ</td><td> 3,9</td><td></td><td></td>

<td>transmittance (not heated)</td><td> 32,1</td><td> -1,8</td><td> -5,93</td>

<td>transmittance (heated)</td><td> 33,4</td><td> -1,55</td><td> -3,82</td>

<td>ΔΕ</td><td> 2,5</td><td></td><td></td>

Before heat treatment, the emissivity normal (E_n) and hemispherical (Eh) were 0.55 and 0.54 respectively, and the sheet resistance (R_s) was 108 ohms / square. After heat treatment, En and Eh were 0.48 and 0.49, respectively, and R_s was 89 ohms / square. Again, each of these values ​​shows little variation according to the above-formulated definition of heat treatability.

<img file="PL183571B1_D0001.tif" />

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