Heat treatable coated article with chromium nitride ir reflecting layer and method of making same

The present invention relates to heat treatable coated articles and heat treated coated articles consisting of a layer system on a glass substrate and a method of making the same. Coated articles according to the invention include an infrared (IR) reflecting layer. Such coated articles may be used in the manufacture of unitary windows, insulated glass (IG) window units, laminated windows, and / or other suitable applications.

Background of the invention

There is a known need for the color matching capabilities of coated articles (before heat treatment vs. after heat treatment). Glass substrates are often manufactured in large numbers and cut to size to meet the needs of a specific situation, such as new multiple windows and office doors, other window requirements, etc. In such applications it is often desirable that a portion of the windows and / or doors be heat treated (i.e., heat treated, heat set or bent) while others do not. In office buildings, IG units and / or laminates are often used for safety and / or thermal control reasons. It is often desirable that such heat treated (HT) units and / or laminates substantially match their untreated counterparts (e.g. in terms of color, reflectance, and / or the like) for construction and / or construction reasons. aesthetic.

US Patent No. 5,543,229 to Asahi Glass Company Ltd. discloses a heat treated coated article that includes a four (or more) layer system deposited on a glass substrate. The system includes a solar radiation limiting layer interposed between the first and second dielectric layers, where the second layer is at least partially nitrided. The solar-limiting or electrically conductive layer comprises a metal, such as stainless steel, titanium, chromium, zirconium, tantalum, hafnium, silver or aluminum, on a glass substrate. Patent 5,543,229 does not disclose or suggest the use of only three layers, of which the silicon nitride layer farthest from the substrate is thicker than the layer containing chromium nitride, and the layer structure claimed therein requires a large number of steps to be produced.

US Patent No. 5,376,455 discloses a coated article including: glass / Si₃N₄/ NiCr / Ag / NiCr / Si₃N₄. Unfortunately, the coating system of Patent 5,376,455 cannot be sufficiently color matched after heat treatment with its untreated counterpart. In other words, the coating system of Patent 5,376,455 has a fairly high ΔΕ value. This means, unfortunately, that two different coated articles with different coatings (one heat treated and one untreated) need to be produced for customers who want their heat treated and non-heat treated coated articles to be approximately color matched in the case of observation with the naked eye.

According to Patent 5,376,455 it was mostly possible to achieve conformability only by providing two different layer systems, one which was heat treated (HT) and the other which was not heat treated. The need to develop and use two different layer systems in order to achieve conformability creates additional manufacturing costs and the need to stock up on reserves, which is undesirable.

However, US Patent No. 5,688,585 to the same proprietor discloses a solar limiting coated article including glass / Si3N4 / NiCr / Si3N4 where the conformability was achieved with a single layer system. As explained at column 9 of Patent 5,688,585, it is a "requirement" of Patent 5,688,585 that the NiCr layer be substantially free of any nitride. The purpose of Patent 5,688,585 is to provide a sputter-coated layered system which, after heat treatment, allows color matching with its untreated counterpart. However, Patent 5,688,585 used a heat treatment (HT) for only three (3) minutes (col. 10, line 55). Longer heat treatments are often desired in order to achieve better toughening or HT characteristics. Unfortunately, as explained below, it has been found that for longer HT times, the coatings of Patent 5,688,585 cannot maintain low ∆Ε values ​​and thus lose their color matching ability.

Considering the following layer stack: glass / Si₃N₄/ NiCr / Si₃N₄, where the Si₃N₄is about 50-70 A (angstroms) thick, the NiCr layer is about 325 A thick, (the NiCr layer is not nitrided during deposition as can be seen in Figure 15) and the Si face layer₃N₄it is about 210-310 A in thickness. It has been found that some nitriding with NiCr may possibly occur during the heat treatment. Unfortunately, taking into account the deposited NiCr layer, this product

The coated material has a fairly high transmissive value ∆Ε * of about 5.9 after heat treatment (HT) at 625 degrees C for ten (10) minutes. This high transmissive ΔE value means that the HT version of the coated article with 5,688,585 approximately does not match the color of the untreated counterparts for color transmittance after 10 minutes of HT. Moreover, such stacks have a glass side reflective ΔE * value greater than 5.0 after heat treatment (HT) at 625 degrees C for ten minutes. These high glass side reflective ΔΕ values ​​are undesirable, and prevent matchability between heat treated and non heat treated versions of the same coating.

Unfortunately , a stack of glass / Si layers₃N₄/ NiCr / Si₃N₄wherein the Ni / Cr ratio is 80/20, while providing effective solar control and an overall good coating system, is also sometimes insufficient with respect to: (a) acid corrosion resistance (e.g., boiling HCl); and (b) mechanical performance such as scratch resistance; in addition to the problems described above related to (c) heat stability after heat treatment for tempering, heat bending or the like (i.e., the ΔE * value (s).

Accordingly, there is a need for a coated article that has improved characteristics with respect to (a), (b) and / or (c) over a conventional glass / Si layer stack.₃N₄/ NiCr / Si₃N₄but which still achieves acceptable solar control (e.g., blocking significant amounts of IR and / or UV radiation) and / or heat treatment. It is an object of the present invention to meet at least one of the above-mentioned needs, and / or other needs that will become apparent to those skilled in the art from reading the following disclosure.

Summary of the invention

The present invention relates to a heat treated coated article consisting of a layer system deposited on a glass substrate, the layer system consisting of a first dielectric layer and a second dielectric layer and a metal nitride inclusive layer interposed therebetween, wherein the metal nitride inclusive layer comprises nitride chrome, has a thickness of 100-300 A, and is disposed between and in contact with the first dielectric layer and the second dielectric layer both of which contain silicon nitride, the second dielectric layer including silicon nitride being placed such that the layer including chromium nitride is positioned between the second dielectric layer including silicon nitride and the glass substrate;

wherein the first dielectric layer containing silicon nitride is 50-900 Å thick; wherein the second dielectric layer containing silicon nitride has a thickness of 200-400 Å and is thicker than the layer containing chromium nitride;

wherein the coated article has a ∆Ε * (glass side reflective and / or transmissive) value of no greater than 4.0 after a heat treatment of at least 600 ° C; and wherein the chromium nitride is characterized by a ratio defined as Cr_xN_ywhere y / x is from 0.25 to 0.7.

Preferably, the coated article of this invention has a ∆Ε * value (glass side reflective and / or transmissive) of no greater than 3.0 after the above heat treatment.

More preferably, the coated article of this invention has a ∆Ε * value (glass side reflective and / or transmissive) of no greater than 2.5 after the above heat treatment.

Even more preferably, the coated article of this invention has a ∆Ε * (glass side reflective and / or transmissive) value of no greater than 2.0 after the above heat treatment.

Preferably, the coated article of this invention has a ∆Ε * (glass side reflective) value of no greater than 3.0 after the above heat treatment.

Preferably, in the coated article of the invention, chromium nitride is characterized as Cr_xN_ywhere y / x is from 0.3 to 0.6.

More preferably, in the coated article of the invention, chromium nitride is characterized as Cr_xN_ywhere y / x is from 0.45 to 0.55.

Preferably, in the coated article of this invention, the layer comprising chromium nitride contains from 55 to 90 atomic% chromium, and from 15 to 50 atomic% nitrogen.

In another aspect, the invention provides a heat treatable coated article comprising a coating deposited on a glass substrate, the coating comprising a first dielectric layer, a layer containing metal nitride, and a second dielectric layer, wherein the layer containing the metal nitride comprises nitride. chromium, having a thickness of 100-300 Å, and sandwiched between the first dielectric layer and the second dielectric layer;

wherein the first dielectric layer comprises silicon nitride, having a thickness of 50-900 Å;

Wherein the second dielectric layer comprises silicon nitride, having a thickness of 200-400 Å, and is thicker than the layer including chromium nitride; and wherein the layers of the coated article include suitable thicknesses and materials such that if a heat treatment is performed at a temperature of at least 600 ° C, the coated article will have a ∆Ε * value not greater than 3.0; and wherein chromium nitride is characterized as Cr_xN_ywhere y / x is 0.45 to 0.55.

In another aspect, the invention provides a method of making a coated article that includes forming a coating by sputtering a first dielectric layer on a substrate, sputtering a layer containing metal nitride on a substrate over the first dielectric layer, sputtering a second dielectric layer on the substrate over a layer containing metal nitride. , characterized in that the obtained coating consists of the first dielectric layer, a layer comprising metal nitride and a second dielectric layer, wherein a first dielectric layer comprising silicon nitride is cathodically sputtered on the substrate, a metal nitride inclusive layer comprising chromium nitride is cathodically sputtered over and in contact with the first dielectric layer, and the second layer is cathodically sputtered a dielectric layer containing silicon nitride over and in contact with the layer containing chromium nitride, and wherein the first dielectric layer comprising silicon nitride has a thickness of 50-900 Å;

where the layer containing chromium nitride has a thickness of 100-300 Å;

wherein the second dielectric layer containing silicon nitride has a thickness of 200-400 Å and is thicker than the layer containing chromium nitride in the finished article; the layer comprising chromium nitride is sputtered cathodically to form Cr_xN_ywhere y / x is from 0.25 to 0.7.

Preferably, the method of the invention further comprises heat treating the coated article to a temperature of at least 580-600 ° C, the coated article having a ∆Ε * (glass side reflective and / or transmissive) value of no greater than 3.0 following the heat treatment.

Preferably, the method of the invention further comprises heat treating the coated article to a temperature of at least 625 ° C, the coated article having a ∆Ε * (glass side reflective and / or transmissive) value of no greater than 3.0 following the heat treatment.

In certain example embodiments, a coating or layering is provided that consists of an infrared (IR) reflecting layer including chromium nitride sandwiched between a pair of dielectric layers. In certain example embodiments, the coating or layering exhibits good acid corrosion resistance such as HCl, good mechanical performance such as scratch resistance, and / or good color fastness (i.e., low ΔΕ * value (s) after processing. thermal (HT).

For example, it has been found that a coating or layer system including an infrared reflecting layer comprising chromium nitride has better durability (e.g., in terms of acid exposure) than the above-mentioned conventional coating including an infrared reflecting layer made of NiCr. Moreover, it has surprisingly been found that the use of chromium nitride as an infrared reflecting layer enables the solar control coating to exhibit much better durability after heat treatment (e.g., a lower ΔΕ * value for a given heat treatment time) than the above-mentioned conventional coating in which the Metallic NiCr is used to reflect infrared radiation.

Coated articles according to certain embodiments of this invention can be used as unitary windows due to their excellent durability characteristics which may or may not be heat treated. Alternatively, coated articles according to the present invention may also be used in the context of insulating glass window units or any other suitable application which may or may not require heat treatment.

In certain example embodiments of this invention, heat treated (HT) coated articles including an infrared reflecting layer made of chromium nitride have a ∆Ε * (glass side reflective and / or transmissive) value of no greater than 5.0, even more preferably. no greater than 4.0, more preferably no greater than 3.0, and more preferably no greater than 2.5, even more preferably no greater than 2.0, and most preferably no greater than 1.8. By way of example, the heat treatment (HT) may be for a minimum of 5 minutes at a temperature of at least 580 degrees C, and may be at a temperature of at least 600 degrees C for a period of at least 5 minutes (more preferably at least 7 minutes, and most preferably at least 7 minutes, and most preferably at least 7 minutes). 9 minutes), in certain example embodiments.

In certain example embodiments, an infrared reflecting layer made of chromium nitride may be depicted as Cr_xN_ywhere the ratio y / x is from 0.25 to

PL 223 451 B1

0.7, even more preferably from 0.3 to 0.6, even more preferably from 0.45 to 0.55. For example purpose only, Cr₂N translates to a y / x ratio of 1/2 (i.e., 0.5). It has surprisingly been found that this particular y / x ratio range (s) for chromium nitrides (Cr) is particularly useful in terms of thermal, optical and / or durability characteristics. For example, nitriding with Cr greater than that stated may result in reduced durability (e.g., mechanical and / or chemical resistance).

Description of the drawings

Figure 1 is a partial cross sectional view of an embodiment of a unitary coated article (heat treated or not heat treated) according to an example embodiment of this invention.

Figure 2 is a partial cross sectional view of an IG window unit such as that contemplated in the present invention in which the coating or layer system of Figure 1 may be used.

Figure 3 is a graph that plots nitrogen gas flow as% of total gas flow during sputtering the chromium nitride layer vs. the Cr, N atomic content of the resulting coating, illustrating the stoichiometry of the chromium nitride layers according to various embodiments of this invention as a function of nitrogen gas flow during sputtering (N and Cr atomic percentages were determined by XPS photo-electron spectroscopy).

Figure 4 is a graph that plots the nitrogen gas flow as a percentage of the total gas flow during sputtering a chromium nitride layer vs. obtained y / x ratio (data Cr_xN_y) in the resulting chromium nitride layer according to various embodiments of this invention, thereby illustrating the different stoichiometry of the layer as a function of the amount of nitrogen in the total gas flow during sputtering (N and Cr atomic percentages were determined by XPS photo-electron spectroscopy).

Figure 5 is a graph that plots the nitrogen gas flow (in standard cubic centimeters) during sputtering a chromium nitride layer vs. obtained y / x ratio (CrxNy data in the resulting chromium nitride layer according to various embodiments of the present invention, thus illustrating the different stoichiometry of the layer as a function of nitrogen gas flow during sputtering (atomic percentages N and Cr were determined by X-ray photo-electron spectroscopy XPS ).

Detailed Description of the Invention

Certain embodiments of the present invention provide a coating or sandwich system that can be used in windows such as solid windows (e.g., vehicle, residential or building windows), IG window units, and / or other suitable applications. Certain example embodiments of this invention provide a sandwich system that has good (a) resistance to acid corrosion (e.g., which can be tested in boiling HCl); (b) mechanical performance, such as scratch resistance; and / or (c) thermal stability during heat treatment. Regarding the thermal stability after heat treatment (HT), this means a low ΔΕ * value (reflective and / or transmissive on the glass side); where Δ indicates the change from the point of view of thermal treatment such as quenching, heat bending or thermal heating to strengthen, monolithic and / or in the context of the surrounding of double panes such as IG units or laminates. In certain example embodiments, such heat treatments sometimes involve heating the coated substrate to a temperature from about 580 ° C to about 800 ° C for 4-5 minutes or more, and in some embodiments at a furnace set point temperature of about 600 ° C for a period of time as at least 4 or 5 minutes (more preferably at least 7 minutes, and most preferably at least 9 minutes).

Figure 1 is a side cross sectional view of a coated article according to an example embodiment of this invention. The coated article comprises a substrate 1 (e.g., a clear, green, brown, gray, blue, or cyan glass substrate from about 1.0 to 12.0 mm thick), a first dielectric layer 2 (including silicon nitride, e.g. Si₃N₄), an infrared reflection layer 3 comprising chromium nitride (Cr_xN_y), and a second dielectric layer 4 (containing silicon nitride, e.g., Si₃N₄).

In certain example embodiments of this invention, infrared reflecting layer 3 is substantially free of Ni (i.e., no more than about 10% Ni, more preferably no more than 5% Ni, even more preferably no more than 1% Ni, and most preferably no Ni, and most preferably no Ni. more than 0.01% Ni).

The total coating 5 comprises layers 2-4. It is noted that the terms "oxide" and "nitride" in the context of the present invention encompass different stoichiometry. For example, the term silicon nitride

PL 223 451 B1 includes stoichiometric Si₃N₄as well as non-stoichiometric silicon nitride such as Si enriched silicon nitride. Layers 2-3 may be deposited on substrate 1 by magnetron sputtering or any other suitable technique in various embodiments of this invention.

In certain example embodiments of this invention, infrared reflecting layer 3 is sputter deposited in the form of chromium nitride. The stoichiometry of this layer, when deposited, may be represented, in certain example embodiments, by Cr_xN_ywherein the ratio y / x (i.e., ratio of N to Cr) is from 0.25 to 0.7, more preferably from 0.3 to 0.6, even more preferably from 0.45 to 0.55. For purposes of example only, chromium nitride in the form of Cr₂N translates into a y / x ratio of 1/2. (that is, 0.5). It has surprisingly been found that the above-mentioned y / x ratio ranges for chromium nitrides are particularly useful with regard to coating characteristics such as durability and optical quality. For example, nitriding of Cr in amounts greater than this (approaching CrN where y / x = 1) may result in lower chemical resistance of coating 5 and / or poor adhesion to silicon nitride, especially after heat treatment. In other words, the durability is lowered in some cases if the y / x ratio is greater than the above-mentioned range.

It was surprisingly found that the use in the 3 Cr_xN_y (unlike NiCr) results in a coated article having: (a) improved resistance to corrosion by acid such as HCl; (b) improved mechanical durability; 1 (c) improved color fastness after heat treatment (i.e., lower AE * value (s)).

In certain example embodiments of this invention, each of the antireflective dielectric layers 2 and / or 4 may have a refractive index "n" of from about 1.5 to 2.5, more preferably from 1.9 to 2.3. In embodiments of the present invention wherein layers 2 and / or 4 contain silicon nitride (e.g., Si₃N₄), the Si-containing sputtering targets used to form these layers may or may not be doped with 6-20% by weight of aluminum and / or stainless steel (e.g. SS # 316), with about the same amount appearing thereafter in the layers produced in this way.

While Figure 1 illustrates a coated article according to an embodiment of this invention in unitary form, Figure 2 illustrates the coating or layering 5 of Figure 1 applied to surface # 2 of an IG (insulating glass) window unit. In Figure 2, two glass substrates (e.g., 2mm to 12mm thick float glass) 1, 7 are sealed at the peripheral edges with conventional sealant and / or spacer (not shown) and may be provided with conventional tape. a drying agent (not shown). The panes are then held in a conventional window or door mounting frame. By sealing the peripheral edges of the glass sheets and replacing the air in the insulation space (or chamber) 9 with a gas such as argon, a highly insulating IG unit value as shown in the Figure is produced. 2

Optionally, insulating space 9 may be pressurized below atmospheric pressure in certain other embodiments, although this is of course not necessary in all IG embodiments. In IG embodiments, the coating 5 of Figure 1 may be provided on the inner wall of substrate 1 (as in Figure 2), and / or on the inner wall of substrate 7.

Returning to Figure 1, different thicknesses may be used in accordance with one or more of the objects and / or needs considered above. According to the present invention, the thicknesses and materials suitable for the individual layers on the glass substrate 1 are as follows:

Table 1

<td>Layer</td><td>Thickness range (A)</td>

<td>Silicon nitride (layer 2)</td><td>50-900 A.</td>

<td>CrxNy (layer 3)</td><td>100-300 A.</td>

<td>Silicon nitride (layer 4)</td><td>200-400 A.</td>

In certain example embodiments, the color fastness due to HT can result in significant matchability between the heat treated and untreated versions of the coating or layer system. In other words, for unitary and / or IG applications, in some embodiments of the present invention, two glass substrates having the same coating system applied (one HT after depositing and the other not HT subjected) appear to be judged to be

With the naked human eye essentially the same. To express this in yet another way, the coated article has good post-HT color fastness.

The value of ∆ Wartość * is important in determining whether there is color fastness or remarkable post-HT color matchability in the context of certain embodiments of this invention (i.e., the term ∆Ξ * is important in determining color fastness post-HT). The color in this patent application has been described with reference to typical a *, b * values. For example, the term ∆8 * indicates how much the color value of a * changes with HT.

The term ΔΕ * (and ΔE) is well understood and described, along with various techniques for its determination, in ASTM 2244-93 as well as described by Hunter et al., The Measurement of Appearance, 2^{n / a} Ed. chap. 9, page 162 et seq. (John Wiley &amp; Sons, 1987). As used, ∆E * (and ∆Ε) is a way of adequately expressing the change (or lack thereof) in reflectance and / or transmittance (and thus also color appearance) of an article after or due to HT. ΔΕ can be calculated using the "ab" technique or the Hunter technique (denoted by the use of subscript "H"). ΔΕ corresponds to the L, a, b scale; Hunter Lab (or L._h, a_h, b_h).

Similarly, ΔE * corresponds to the L *, a *, b * CIE LAB scale. Both are considered to be useful and equivalent for the purposes of the present invention. For example, as described above by Hunter et al., A rectangular coordinate / scale technique (CIE LAB 1976) known as the L *, a *, b * scale can be used, in which "

L * means (CIE 1976) luminous units a * means (CIE 1976) red-green units b * means (CIE 1976) yellow-blue units and the distance ΔE * between L *_about and*_about b *_about and L *₁ and*₁ b *_and is:

ΔΕ * = {^ L *)²+ (Aa *)² + ^ b *)²}^1/2 where:

Δυ * = L * 1 - L * o (2)

Δa * = a *₁ - a *_about (3)

Ab * = b * 1 - b * o (4) where "o)" subscript is the coating (or coated article) before heat treatment and the subscript "1" is the coating (coated article) after heat treatment; and the numbers used (e.g., a *, b *, L *) are those calculated by the L *, a *, b * coordinate technique mentioned above (CIE LAB 1976). Similarly, ΔE can be calculated using equation (1) by replacing a *, b * L * with the values ​​of Hunter Lab a_h, b_h, L._h. Also within the scope of the present invention and in estimating ∆E * they are equivalent numbers if converted to those calculated by any other technique that uses the same concept of ∆E * as defined above.

After heat treatment (HT) such as quenching, and in certain example embodiments of this invention, coated articles have color parameters such as those in Table 2. The subscript "G" is indicated to correspond to the glass side reflective color, "T" subscript corresponds to transmissive color, and "F" subscript corresponds to the color facing the film. As is known, the glass side (G) is reflective color when viewed from the glass side (as opposed to the layer / film side) of the coated article. The film side (F) (not shown in Table 2) represents a reflective color when viewed from the side of the coated article on which the coating 5 is provided.

Table 2: Color parameters after heat treatment

<td></td><td>general</td><td>beneficial</td><td>the most advantageous</td>

<td>ΔΕ * ο</td><td> &lt; = 5,0</td><td> &lt; = 4,0</td><td> &lt; = 3,0</td>

<td>AE * Vol</td><td> &lt; = 5,0</td><td> &lt; = 4,0</td><td> &lt; = 3,0</td>

<td>a * G</td><td>-6 to +6</td><td>-4 to +4</td><td>-3 to +3</td>

<td>b * G</td><td>-30 to +25</td><td>-25 to +20</td><td>-20 to +10</td>

<td>Δa * G</td><td> &lt;=1,0</td><td> &lt;=0,7</td><td> &lt;=0,5</td>

<td>Δb * G</td><td> &lt;=1,5</td><td> &lt;=0,8</td><td> &lt;=0,5</td>

<td>ΔL * G</td><td> &lt;=5</td><td> &lt;=3</td><td> &lt;=2</td>

<td>^T.vis</td><td> 8-80%</td><td> 10-50%</td><td> 10-30%</td>

<td>Rs (Ω / kw.):</td><td> &lt;250</td><td> &lt;150</td><td> &lt;110</td>

PL 223 451 B1

The post-HT coated articles in this patent application may even have a ∆Ε * (glass side reflective and / or transmissive) value (s) of no greater than 2.5, more preferably no greater than 2.0, and sometimes not even greater than 1. 8, in certain example embodiments of this invention. In certain example embodiments, the post-HT coated articles in this patent application may even have a ∆Ε * value (s) (glass side reflective and / or transmissive) of no greater than 1.5, or even 1.2.

Figures 3-5 illustrate different stoichiometry of the silicon nitride layer 3 according to various embodiments of the present invention. In particular, these figures illustrate different N to Cr ratios (y / x ratios) in the chromium nitride layer 3 as a function of nitrogen gas flow during the sputtering process in which the layer 3 is sputter deposited. In these figures, the atomic percentages of N and Cr (atomic%) were determined by XPS. In addition, it is noted that the correlation between the nitrogen gas flows and the N to Cr ratio (s) was determined according to the ILS coater used to deposit these samples as the flows were measured on this sputter coater.

Figure 3 is a graph that plots, during sputtering a chromium nitride layer, the nitrogen gas flow as a percentage of the total gas flow (e.g., where Ar and N gases are used) vs. the Cr, N atomic content of the resulting layer 3, illustrating the stoichometry of the chromium nitride layers according to various embodiments of this invention as a function of nitrogen gas flow. Figure 4 is a graph that plots the nitrogen gas flow as a percentage of the total gas flow during sputtering a chromium nitride layer vs. obtained ratio y / x (data Cr_xN_y) in the resulting chromium nitride layer according to various embodiments of the present invention, thus illustrating the different stoichiometry of the layer as a function of the amount of nitrogen in the total gas flow during sputtering. Figure 5 is a graph that plots the nitrogen gas flow (in standard units of cubic centimeters) during sputtering a chromium nitride layer vs. obtained ratio y / x (data Cr_xN_y) in the resulting chromium nitride layer according to various embodiments of the present invention, thus illustrating the different stoichiometry of the layer as a function of nitrogen gas flow during sputtering.

As explained above, the best performance (balanced durability and sun protection) surprisingly appears when the Cr_xN_y 3 is defined by a ratio of N to Cr, y / x, equal to 0.25 to 0.7, even more preferably 0.3 to 0.6, even more preferably 0.45 to 0.55.

For purposes of illustration only, a plurality of examples representing various exemplary embodiments of the present invention are provided below.

Examples 1-2

Examples 1-2 were uniform coated articles (each finally annealed and heat treated). The Si3N4 layers 2 and 4 in each example were deposited by sputtering a silicon target (doped with about 10% Al) in an atmosphere containing nitrogen gas. The chromium nitride layer 3 in each example was sputter-deposited in an atmosphere containing argon and nitrogen gas.

In Example 1, the following sputtering process parameters were used to deposit the coating. Linear velocities are expressed in inches per minute (IPM), and gas flows (Ar and N) are given in standard cubic centimeters units:

TABLE 3: Example 1 Coating process parameters

<td>layer</td><td>power</td><td>tension</td><td>Speed linear</td><td>number waveforms</td><td>Flow Ar</td><td>Flow N</td>

<td>SiN layer 2</td><td>1.0 kW</td><td>463 V</td><td> 41,2</td><td> 2</td><td> 40</td><td> 40</td>

<td>CrxN_y layer 3</td><td>1.0 kW</td><td>392 V</td><td> 41,5</td><td> 2</td><td> 45</td><td> 15</td>

<td>SiN layer 4</td><td>1.0 kW</td><td>462 V</td><td> 41,2</td><td> 7</td><td> 40</td><td> 40</td>

In Example 2, the following sputtering process parameters were used to deposit the coating. Again, the linear velocity is given in inches per minute (IPM), and gas flows are given in standard cubic centimeters (sccm) units:

PL 223 451 B1

TABLE 4: Example 2 Coating process parameters

<td>layer</td><td>power</td><td>tension</td><td>Speed linear</td><td>number waveforms</td><td>Flow Ar</td><td>Flow N</td>

<td>SiN layer 2</td><td>2.5 kW</td><td>501 V</td><td> 44,5</td><td> 8</td><td> 40</td><td> 55</td>

<td>CrxNy layer 3</td><td>1.0 kW</td><td>393 V</td><td> 38,1</td><td> 2</td><td> 45</td><td> 15</td>

<td>SiN layer 4</td><td>2.5 kW</td><td>502 V</td><td> 41,3</td><td> 2</td><td> 40</td><td> 55</td>

Examples 1-2 after sputtering (after annealing and without HT treatment) had the following parameters (111 C, 2-step observation):

Table 5: Parameters (without HT)

<td>Parameter</td><td>Example 1</td><td>Example 2</td>

<td>Tvis (TY) (permeable)</td><td> 22,5%</td><td> 20,9%</td>

<td>a * T</td><td> -0,9</td><td> -1,1</td>

<td>b * T</td><td> -4,6</td><td> 2,4</td>

<td>L * t</td><td> 54,5</td><td> 52,8</td>

<td>RgY (reception from glass side%)</td><td> 31,5%</td><td> 18,5%</td>

<td>a * G</td><td> -2,2</td><td> -1,1</td>

<td>b * G</td><td> -4,2</td><td> -19,0</td>

<td>L * g</td><td> 62, 9</td><td> 50,1</td>

<td>RfY (pickup from movie side%)</td><td> 20,7%</td><td> 34,7%</td>

<td>a * F</td><td> 0,3</td><td> 0,1</td>

<td>b * F</td><td> 24,4</td><td> 17,6</td>

<td>L * f</td><td> 52,6</td><td> 65,5</td>

<td>Tsol (TS):</td><td> 18%</td><td> 18%</td>

<td>Shading coefficient (SC):</td><td> 0,39</td><td> 0,41</td>

<td>SHGC (Solar Energy Coefficient):</td><td> 0,33</td><td> 0,35</td>

<td>Tuv (UV transmission):</td><td> 20,3%</td><td> 16,0%</td>

<td>Rs (specific resistance, ohm / kw)</td><td> 86,4</td><td>on</td>

Examples 1 and 2 each had the following stack of layers as shown in Table 6. The thicknesses and stoichiometry given below in Table 6 for Examples 1-2 are approximate and not exact. The coating 5 for each Example is shown in Figure 1, and thus includes layers 2, 3, and 4. In each Example, the glass substrates were transparent and about 6 mm thick.

TABLE 6: Coatings in the Examples

<td>Example 1:</td><td>Glass / Si₃N4 (100) / CrxNy (170 A) / SisN (350 A)</td>

<td>Example 2:</td><td>Glass / SiaN4 (890) / CrxNy (185 A) / SisN (240 A)</td>

After sputtering, Examples 1 and 2 were each then heat treated for 10 minutes at about 625 degrees C. Table 7 below lists some of the color fastness parameters of Examples 1-2 after heat treatment (HT).

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Table 7: Durability of the reflective color on the glass side after heat treatment

<td>Parameter</td><td>Example 1</td><td>Example 2</td>

<td>ae * g</td><td> 0,8</td><td> 1,7</td>

As can be seen from Table 7, Examples 1-2 had excellent glass side reflective ∆Ε * values. The low numbers associated with these values ​​illustrate how little the optical characteristics of the coating changed after heat treatment. This is an indicator of higher durability after heat treatment (e.g., quenching or the like).

For comparison, the following layer stack was considered: glass / Si₃N₄/ NiCr / Si₃N₄which, after heat treatment (HT) at 625 degrees C for ten minutes, has a glass side reflective value ΑΕ * greater than 5.0. The above Examples 1-2 clearly illustrate the relative advantage of using chromium nitride as opposed to NiCr in the IR reflecting layer. By using chromium nitride, a much lower ΔE * reflective value on the glass side can be obtained. Moreover, also the durability can be improved as explained above.

Examples 3-5

As mentioned above, it was surprisingly found that considering Cr_xN_y in layer 3, the ratio y / x (i.e., ratio of N to Cr) of 0.25 to 0.9, even more preferably 0.3 to 0.7, even more preferably 0.3 to 0.6, is better than the other ratios in terms of durability and optical characteristics. Examples 3-5 provided below illustrate how diverse Cr_xN_y layers 3 have been made in a coater (sputtering) according to various embodiments of the present invention, in a variety of ways that maintain the y / x ratio within the range of 0.25 to 0.9. Examples 3-5 were sprayed onto 3 mm clear glass substrates with no silicon nitride layers thereon. The atomic percentages for the resulting chromium nitride layers of the Examples were measured by XPS, as was the y / x ratio (Cr data_xN_y).

TABLE 8: Sputtering for Examples 3-5

<td>Feature</td><td>Example 3</td><td>Example 4</td><td>Example 5</td>

<td>Substance:</td><td>CrxN_y</td><td>CrxN_y</td><td>CrxN_y</td>

<td>Power (kW):</td><td> 1</td><td> 1</td><td> 1</td>

<td>U (V):</td><td> 397</td><td> 399</td><td> 402</td>

<td>Pressure (mTorr):</td><td> 1,8</td><td> 2,0</td><td> 2,4</td>

<td>Ar flow (sccm):</td><td> 45</td><td> 45</td><td> 45</td>

<td>Flow N (sccm):</td><td> 10</td><td> 20</td><td> 30</td>

<td>% of flow N (N / N + Ar):</td><td> 18,2</td><td> 30,8</td><td> 40,0</td>

<td>Cr atomic%:</td><td> 74,4</td><td> 62,8</td><td> 56,2</td>

<td>atomic% N:</td><td> 24,5</td><td> 35,8</td><td> 40,2</td>

<td>Y / x ratio</td><td> 0,33</td><td> 0,57</td><td> 0,72</td>

From the above Table 8, a variety of methods can be observed by which the silicon nitride layer can be cathodically sputtered such that the y / x ratio for N to Cr is in the desired range. In certain embodiments of this invention, the Cr atomic% in layer 3 is from 55 to 90%, more preferably from 60 to 85%, and even more preferably from 65 to 75%; while the N atomic% in layer 3 is from 15 to 50%, more preferably from 20 to 40%, and most preferably from 24 to 36%. These atomic% amounts of Cr and N surprisingly result in improved color fastness due to heat treatment (ie, low ∆Ε *) combined with improved color fastness.

Accordingly, the benefits of using chromium nitride as an infrared reflecting layer include (a) improved corrosion resistance with respect to an acid such as HCl; (b) improved mechanical characteristics, such as better scratch resistance; and / or (c) improved thermal stability (ie, low ΔΕ * value (s)). In certain embodiments of this invention, coated articles may or may not be heat treated.

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Certain terms are commonly used in the glass coating field, particularly in determining the solar control properties and characteristics of coated glass. Such terms are used in this patent application according to their well-known meaning. For example, as used in this patent application:

The intensity of the reflected light in the visible wavelength range, that is, the "reflectance" is defined by its percentage ratio and given as R_XY (that is, the Y value quoted below in ASTM E-308-85) where "X" is both "G" for the glass side and "F" for the film side. The "side of the glass" (ie, "G") means to look from the side of the glass substrate opposite to that on which the coating is located, while the "side of the film (ie," F ") means to look from that side of the glass substrate on which there is a shell.

Color parameters were measured and reported in this patent application using CIE LAB a *, b * coordinates and scale (ie, CIE a * b * plot, I11. CIE-C, 2-step observation). Other similar coordinates may be used equivalently, such as subscript "h" to denote a typical Hunter Lab Scale application, or I11. CIE-C, 10 ° observation, or CIE LUV u * v * coordinates. These scales are defined in this patent application according to ASTM D2244-93 Standard Test Method for Calculation of Color Differences from Instrumentally Measured Color Coordinates 9/15/93 as extended in ASTM E-308-85, ASTM Standards Yearbook, Vol. 06.01 Standard Method for Computing the Colors of Objects by 10 Using the CIE System and / or as depicted in IES LIGHTING HANDBOOK 1981 Reference Volume.

The terms "emittance" and "transmittance" are well understood and are used in this patent application according to their well-known meanings. So, for example, the terms visible light transmittance (TY), infrared transmittance, and ultraviolet transmittance (T_uv) are known. Total solar energy transmittance (TS) is therefore usually characterized as a weighted average of these values ​​from 300 to 2500 nm (UV, visible and near infrared radiation). With respect to these transmittances, visible transmittance (TY) as described in this patent application is determined by the standard CIE Illuminant C, 2-step observation technique, at 380-730 nm; near infrared is 720-2500 nm; ultraviolet is 300-380 nm; and total solar radiation is 300-2500 nm. For the purposes of emittance, however, a specific infrared range (i.e., 2500-40,000 nm) is used.

Visible transmittance can be measured using known, conventional techniques. For example, using a spectrophotometer such as a Perkin Elmer Lambda 900 or Hitachi U4001, a spectral transmission curve is obtained. Visible transmittance is then calculated using the ASTM 308 / 12244-93 methodology mentioned above. Less than the recommended number of points for each length may be used, if desired. Another technique for measuring visible transmittance is to use a spectrometer, such as the commercial Spectrogard spectrophotometer manufactured by Pacific Scientific Corporation. This device measures and reports visible transmittance directly. As described and measured in this patent application, visible transmittance (ie, the Y value in a CIE tristimulus system, ASTM E-308-85) uses I11. C., 2-stage observation.

Another term used in this patent application is "proper resistance". Specific resistance (R._s) is a well-known term and has been used in this patent application according to its well-known meaning. It is expressed in this patent application in ohm units per unit area. Generally speaking, the term refers to the resistance in ohms per any square of a layer system on a glass substrate to the electric current flowing through the layer system. Specific resistance is an indicator of how well the layer or layer system is reflecting infrared energy, and is therefore often used along with emittance as a measure of this feature. For example, "specific resistance" may be conveniently measured with a 4 point ohmmeter tester, such as a disposable 4 point resistivity tester from Magnetron Instruments Corp. head, Model M-800 produced by Signatone Corp. from Santa Clara, California.

"Chemical stability" or "chemically stable" is used in this patent application synonymously with the terms "chemically resistant" or "chemically stable". For example, chemical stability can be determined by boiling a sample of the coated glass substrate in about 500 cubic centimeters of 5% HCl for one hour (i.e., about 195 ° F). Alternatively, the chemical stability can be determined by cooking in NaOH, which includes cooking the coated sample

The glass substrate in a solution having a pH of about 12.2, i.e. a mixture of water and NaOH (about 0.4% NaOH); the solution can be obtained from LabChem, Inc., Cat. Well. LC 24270-4 (this is what is meant by cooking in NaOH according to the present patent application). Cooking in NaOH may be performed at about 145 degrees F (Examples above), or about 195 degrees F in other instances.

The terms "heat treatment" and "heat treatment" as used herein mean heating an article to a temperature sufficient to allow the glass-containing article to be thermally tempered, bent, and / or straightened. This definition includes, for example, heating a coated article to a temperature of at least about 580 or 600 degrees C for a time sufficient to permit improvement. In some cases, the heat treatment may be for at least about 4 or 5 minutes.

Many other features, changes, and improvements will become apparent to those skilled in the art upon giving the above disclosure. Such other features, changes and improvements are therefore considered part of the present invention, the scope of which is defined in the following claims.