Patent Description:
Low solar factor (SF) and solar heat gain coefficient (SHGC) values are desired in some applications, particularly in warm weather climates. Solar factor (SF), calculated in accordance with EN standard <NUM>, relates to a ratio between the total energy entering a room or the like through a glazing and the incident solar energy. Thus, it will be appreciated that lower SF values are indicative of good solar protection against undesirable heating of rooms or the like protected by windows/glazings. A low SF value is indicative of a coated article (e.g., IG window unit) that is capable of keeping a room fairly cool in summertime months during hot ambient conditions. Thus, low SF values are sometimes desirable in hot environments. High light-to-solar gain (LSG) values are also desirable. LSG is calculated as Tvis/SHGC. The higher the LSG value, the more visible light that is transmitted and the less amount of heat that is transmitted by the coated article. While low SF and SHGC values, and high LSG values, are sometimes desirable for coated articles such as IG window units and/or monolithic windows, the achievement of such values may come at the expense of sacrificing coloration and/or reflectivity values. In particular, conventional attempts to achieve low SF and SHGC values have often resulted in undesirably high visible reflectance value(s) and/or undesirable visible coloration of the coating. Thus, conventional low-E coatings designed for monolithic window applications typically cannot be used to provide low visible transmission (e.g., <NUM>-<NUM>%), low SHGC performance absent the use of deeply tinted glass substrates. It is often desirable, but difficult, to achieve a combination of acceptable visible transmission (TY or Tvis), desirable reflective coloration (e.g., desirable a* and b* reflective color values), low SF, low SHGC, and high LSG for a coated article in window applications, especially if it desired to use a glass substrate that is not deeply tinted.

SF (G-Factor; EN410-<NUM><NUM>) and SHGC (NFRC-<NUM>) values are calculated from the full spectrum (Tvis, Rg and Rf) and are typically measured with a spectrophotometer such as a Perkin Elmer <NUM>. The SF measurements are done on monolithic coated glass, and the calculated values can be applied to monolithic, IG and laminated applications.

Solar control coatings are known in the art. For example, solar control coatings having a layer stack of glass/Si<NUM>N<NUM>/NiCr/Si<NUM>N<NUM>/NiCr/Si<NUM>N<NUM> are known in the art, where the NiCr layer may be nitrided. For example, see <CIT>. While layer stacks of <CIT> provide reasonable solar control and are overall good coatings, they are lacking in certain respects. The glass side reflective a* values (a* under RGY) in Examples <NUM>, <NUM> and <NUM> in paragraphs <NUM>-<NUM> of US '<NUM> are -<NUM>, - <NUM>, and +<NUM>, respectively, and the glass side visible reflectance values (RGY) in Examples <NUM>, <NUM> and <NUM> are <NUM>%, <NUM>%, and <NUM>%, respectively. Examples <NUM> and <NUM> in US '<NUM> are undesirable because the glass side visible reflectance (RGY) values are too high at <NUM>% and <NUM>%, respectively, and because the glass side reflective a* values are too negative at -<NUM> and -<NUM>, respectively. And when RGY is reduced down to <NUM>% in Example <NUM>, this results in the glass side reflective a* color value in Example <NUM> becoming too red with a value of +<NUM>. Thus, the coatings described in US '<NUM> were not able to achieve a combination of acceptable visible reflectivity values and reflective a* coloration values.

Certain known solar control coatings use NbN, NbZr, or NbZrN as IR reflecting layers. For instance, see <CIT>and <CIT>. However, the instant inventors have surprisingly found that solar control coatings that use solely these materials NbN, NbZr, or NbZrN for IR reflecting layers are lacking in terms of normal emissivity (En) for a given IR reflecting layer(s) thickness. For a given IR reflecting layer(s) thickness, the instant inventors have found that such coatings have undesirably high normal emittance (En) values, undesirably high SHGC values; and undesirably low LSG values. <CIT> discloses a coating over a glass comprising a a dielectric layer comprising Si3N4 covered by a Ni-Cr- nitride, a second dielectric layer comprising siliciumoxynitride covered by a layer comprising titanium nitride and a final layer comprising Si3N4.

It would be desirable according to example embodiments of this invention for a coating to be designed so as to have a combination of acceptable visible transmission (TY or Tvis), desirable reflective coloration (e.g., desirable a* and b* reflective color values), low SF, low SHGC, and high LSG for a coated article in window applications. Note that as visible transmission increases parameters such as SF and SHGC will also increase, and En will decrease, with this being based on the desired transmission for instance of a given coated article for a given application. Coated articles according to example embodiments of this invention substantially reduce the red interior reflective color (e.g., film side reflective red color) while retaining a low interior visible reflectance, while maintaining good mechanical, chemical and environmental durability and low emissivity properties.

In example embodiments of this invention, applications such as monolithic window applications desire reflective coloration that is not significantly red. In other words, applications such as monolithic window applications desire reflective a* color values that are either negative or no greater than +<NUM> or +<NUM> (reflective a* values higher than +<NUM> are undesirably red). Such reflective a* values are desirable in the context of glass side reflective (RG[or outside, or exterior]Y) and/or film side reflective (RF[or inside]Y) a* values.

Embodiments of this invention relate to coated articles that include two or more functional infrared (IR) reflecting layers sandwiched between at least dielectric layers, and/or a method of making the same. The dielectric layers may be of or include silicon nitride or the like. In example embodiments, at least one of the IR reflecting layers is of or including titanium nitride (e.g., TiN) and at least another of the IR reflecting layers is of or including NiCr (e.g., NiCr, NiCrNx, NiCrMo, and/or NiCrMoNx). It has surprisingly and unexpectedly been found that the use of these different materials for the different IR reflecting layers (e.g., as opposed to using TiN for both IR reflecting layers) in a given solar control coating surprisingly results in improved optics such as improved reflective a* values and/or reduced visible reflectivity values which are often desirable characteristics in window applications, and the provision of the IR reflecting layer of or including NiCr allows coated articles to be more easily tailored for desired visible transmission values while the IR reflecting layer of or including TiN can keep the normal emissivity, SF and/or SHGC values reasonably low. Coating according to embodiments of this invention may be designed so that before and/or after any optional heat treatment such as thermal tempering the coated articles realize one or more of: desirable glass side and/or film side reflective visible coloration that is not too red (e.g., reflective a* color value(s) from -<NUM> to +<NUM>); a desirably low solar heat gain coefficient (SHGC); desirable visible transmission (TY or Tvis); thermal stability upon optional heat treatment (HT) such as thermal tempering; desirably low normal emissivity/emittance (En); and/or desirably high light-to-solar gain ratio (LSG). Such coated articles may be used in the context of monolithic windows, insulating glass (IG) window units, laminated windows, and/or other suitable applications.

In example embodiments of this invention there is provided a coated article including a coating supported by a glass substrate, the coating comprising: a first dielectric layer; a first infrared (IR) reflecting layer on the glass substrate over at least the first dielectric layer; a second dielectric layer comprising silicon nitride on the glass substrate over at least the first dielectric and the first IR reflecting layer; a second layer IR reflecting layer comprising a nitride of titanium on the glass substrate over at least the second dielectric layer comprising silicon nitride; a third dielectric layer on the glass substrate over at least the second IR reflecting layer comprising the nitride of titanium; wherein the coating contains no IR reflecting layer based on silver; and wherein the coated article has: a visible transmission from about <NUM>-<NUM>%, a glass side visible reflectance no greater than about <NUM>%, a film side visible reflectance no greater than about <NUM>%, a glass side reflective a* value of from -<NUM> to +<NUM>, and a film side reflective a* color value of from -<NUM> to +<NUM>. as from claim <NUM>.

In example embodiments of this invention, there is provided a method of making a coated article including a coating supported by a glass substrate, the method comprising: sputter-depositing a first dielectric layer comprising silicon nitride; sputter-depositing a first infrared (IR) reflecting layer comprising NiCr on the glass substrate over at least the first dielectric layer comprising silicon nitride; sputter-depositing a second dielectric layer comprising silicon nitride on the glass substrate over at least the first dielectric layer comprising silicon nitride and the first IR reflecting layer comprising NiCr; sputter-depositing a second layer IR reflecting layer comprising a nitride of titanium on the glass substrate over at least the second dielectric layer comprising silicon nitride; and sputter-depositing a third dielectric layer comprising silicon nitride on the glass substrate over at least the second IR reflecting layer comprising the nitride of titanium; wherein the coating contains no IR reflecting layer based on silver; and wherein the coated article has a visible transmission from about <NUM>-<NUM>% and one or more of: (a) a glass side visible reflectance no greater than about <NUM>%, (b) a film side visible reflectance no greater than about <NUM>%, (c) a glass side reflective a* value of from -<NUM> to +<NUM>, and (d) a film side reflective a* color value of from -<NUM> to +<NUM>. as from claim <NUM>.

Thus, this invention covers monolithic window units, IG window units, laminated window units, and any other article including a glass substrate having a coating thereon as claimed. Note that monolithic measurements may be taken by removing a coated substrate from an IG window unit and/or laminated window unit, and then performing monolithic measurements. It is also noted that for a given coating the SF and SHGC values will be significantly higher for a monolithic window unit than for an IG window unit with the same coated article.

<FIG> is a partial cross sectional view of a monolithic coated article (heat treated or not heat treated) according to an example embodiment of this invention.

Referring now more particularly to the accompanying drawings in which like reference numerals indicate like parts throughout the several views.

A coating <NUM> is designed so as to have a combination of acceptable visible transmission (TY or Tvis), desirable reflective coloration (e.g., desirable a* and b* reflective color values), low SF, low SHGC, and high LSG for a coated article for use in window applications or the like. As visible transmission increases when the IR reflecting layer(s) become thinner, parameters such as SF and SHGC will also increase, and En will decrease, with this being based on the desired transmission for instance of a given coated article for a given application. Example applications include architectural windows, residential windows, monolithic windows, automotive windows, and/or IG windows.

Embodiments of this invention relate to coated articles having a coating <NUM> on a glass substrate <NUM>, where the coating includes two or more functional infrared (IR) reflecting layers <NUM> and <NUM> sandwiched between at least dielectric layers <NUM>, <NUM>, <NUM>, <NUM>, and/or a method of making the same. The dielectric layers <NUM>, <NUM> and <NUM> may be of or include silicon nitride or the like. Transparent dielectric overcoat <NUM>, of or including zirconium oxide is present. In example embodiments, at least one of the IR reflecting layers is of or including titanium nitride (e.g., TiN) and at least another of the IR reflecting layers is of or including NiCr (e.g., NiCr, NiCrNx, NiCrMo, and/or NiCrMoNx). In the <FIG> embodiment, upper IR reflecting layer <NUM> is of or including titanium nitride (e.g., TiN) and lower IR reflecting layer <NUM> is of or including NiCr (e.g., NiCr, NiCrNx, NiCrMo, and/or NiCrMoNx). It has surprisingly and unexpectedly been found that the use of these different materials for the different IR reflecting layers <NUM> and <NUM> (e.g., as opposed to using TiN for both IR reflecting layers <NUM> and <NUM>) in a given solar control coating surprisingly results in improved optics such as improved reflective a* values and/or reduced visible reflectivity values which are often desirable characteristics in window applications, and the provision of the IR reflecting <NUM> layer of or including NiCr allows coated articles to be more easily tailored for desired visible transmission values while the IR reflecting layer of or including TiN <NUM> provides for desirably low normal emissivity, SF and/or SHGC values for a given thickness of IR reflecting material. Coating <NUM> according to embodiments of this invention is designed so that before and/or after any optional heat treatment such as thermal tempering the coated articles realize one or more of: desirable glass side and/or film side reflective visible coloration that is not too red (e.g., reflective a* color value(s) from -<NUM> to +<NUM>); a desirably low solar heat gain coefficient (SHGC); desirable visible transmission (TY or Tvis); thermal stability upon optional heat treatment (HT) such as thermal tempering; desirably low En; and/or a desirably high light-to-solar gain ratio (LSG). In example embodiments of this invention, the coating <NUM> contains no IR reflecting layer based on Ag or Au.

In example embodiments of this invention, certain applications such as monolithic window applications desire reflective coloration that is not significantly red. In other words, applications such as monolithic window applications desire reflective a* color values that are either negative or no greater than +<NUM> (reflective a* values higher than +<NUM> are undesirably red). Such reflective a* values are not too red and are desirable in the contact of glass side reflective (RGY) and/or film side reflective (RFY) a* values.

Coated articles may optionally be heat treated in certain example embodiments of this invention, and are preferably designed to be heat treatable. The terms "heat treatment" and "heat treating" as used herein mean heating the article to a temperature sufficient to achieve thermal tempering, heat bending, and/or heat strengthening of the glass inclusive article. This definition includes, for example, heating a coated article in an oven or furnace at a temperature of least about <NUM> degrees C, more preferably at least about <NUM> degrees C, for a sufficient period to allow tempering, bending, and/or heat strengthening. In certain instances, the HT may be for at least about <NUM> or <NUM> minutes. The coated article may or may not be heat treated in different embodiments of this invention.

<FIG> is a cross sectional view of a coated article according to an example embodiment of this invention. In the <FIG> embodiment the solar control coating <NUM> includes two IR reflecting layers <NUM> and <NUM>, and transparent dielectric layers <NUM>, <NUM>, <NUM> and <NUM>. The coated article includes at least glass substrate <NUM> (e.g., clear, green, bronze, grey, blue, or blue-green glass substrate from about <NUM> to <NUM> thick, more preferably from <NUM>-<NUM> thick, with an example glass substrate thickness being <NUM>), transparent dielectric layers <NUM>, <NUM>, <NUM> (e.g., of or including silicon nitride [e.g., Si<NUM>N<NUM>], silicon oxynitride, silicon zirconium nitride, IR reflecting layers <NUM>, <NUM>. It will be appreciated that the IR reflecting layers <NUM> and/or <NUM> are benitrided in example embodiments of this invention. Upper IR reflecting layer <NUM> is of or including titanium nitride (e.g., TiN, preferably a stoichiometric or substantially stoichiometric type) and lower IR reflecting layer <NUM> is of or including NiCr (e.g., NiCr, NiCrNx, NiCrMo, and/or NiCrMoNx). The NiCr may be with respect to metal content about Ni(<NUM>)/Cr(<NUM>) by weight percent, or any other suitable ratio. The lower absorbing IR reflecting layer <NUM> (e.g., of or including NiCr-based metal or NiCr-based nitride) preferably has a refractive index (n) from about <NUM> - <NUM> (at <NUM>) and an extinction coefficient (k) from about <NUM> - <NUM> (at <NUM>). This has surprisingly been found to provide for lower glass and film side visible reflectance and reduced reddish film side reflective color in the final product. The upper IR reflecting layer <NUM> is of or includes TiNx in example embodiments of this invention, where x is preferably from <NUM> to <NUM>, more preferably from <NUM> to <NUM>, with an example value being about <NUM>. These "x" values provide for improved/lowered emittance values compared to if "x" is too low for instance. It has surprisingly and unexpectedly been found that the use of these different materials for the different IR reflecting layers <NUM> and <NUM> (e.g., as opposed to using TiN for both IR reflecting layers <NUM> and <NUM>) in a given solar control coating provides for surprisingly results as explained herein. While the IR reflecting layers may include some small amount of oxygen in certain instances, it is preferable that these layers <NUM> and <NUM> are substantially free of oxygen such as no more than <NUM>% oxygen, more preferably no more than about <NUM>% oxygen, and most preferably no more than about <NUM>% or <NUM>% oxygen in certain embodiments (atomic %). The coated article includes transparent dielectric overcoat layer <NUM> of or including a protective material that is zirconium oxide (e.g., ZrO<NUM>). Optionally, a dielectric layer of or including silicon oxynitride and/or zirconium silicon oxynitride of any suitable stoichiometry may be located between and contacting layers <NUM> and <NUM> in the upper part of the layer stack in certain example embodiments. Coating <NUM> does not include any metallic IR blocking or reflecting layer of or based on Ag or Au. In certain example embodiments of this invention, IR reflecting layers <NUM> and <NUM> reflect at least some IR radiation, and do not contact any other metal or metal based IR reflecting layer. In certain example embodiments, it is possible for each of the layers to include other materials such as dopants.

The overall coating <NUM> of <FIG> includes at least the illustrated layers in certain example embodiments. It is noted that the terms "oxide" and "nitride" as used herein include various stoichiometries. For example, the term silicon nitride (for one or more of layers <NUM>, <NUM>, <NUM>) includes stoichiometric Si<NUM>N<NUM>, as well as non-stoichiometric silicon nitride, and these layers may be doped with other material(s) such as Al and/or O. The illustrated layers may be deposited on glass substrate <NUM> via magnetron sputtering, any other type of sputtering, or via any other suitable technique in different embodiments of this invention. It is noted that other layer(s) may be provided in the stack shown in <FIG> such as between layers <NUM> and <NUM>, or between layers <NUM> and <NUM>, or between the substrate <NUM> and layer <NUM>, or the like. Generally, other layer(s) may also be provided in other locations of the coating. Thus, while the coating <NUM> or layers thereof is/are "on" or "supported by" substrate <NUM> (directly or indirectly), other layer(s) may be provided therebetween. Thus, for example, the layer system <NUM> and layers thereof shown in <FIG> are considered "on" the substrate <NUM> even when other layer(s) may be provided therebetween (i.e., the terms "on" and "supported by" as used herein are not limited to directly contacting). However, there may be the direct contacts shown in <FIG> in preferred embodiments.

In certain example embodiments of this invention, dielectric layers <NUM>, <NUM>, and <NUM> may each have an index of refraction "n" of from <NUM> to <NUM> (at <NUM>), more preferably from <NUM> to <NUM> in certain embodiments, and most preferably from about <NUM> to <NUM> in preferred embodiments of this invention. One, two, three, or all of these layers <NUM>, <NUM>, <NUM> may be of or include silicon nitride and/or silicon oxynitride in certain example embodiments of this invention. In such embodiments of this invention where layers <NUM>, <NUM>, <NUM> comprise silicon nitride (e.g., Si<NUM>N<NUM>), sputtering targets including Si employed to form these layers may or may not be admixed with up to <NUM>-<NUM>% (e.g., <NUM>%) by weight aluminum or stainless steel (e.g. SS#<NUM>), with about this amount then appearing in the layers so formed. Even with this amount(s) of aluminum and/or stainless steel, such layers are still considered dielectric layers. In example embodiments, each of the IR reflecting layers <NUM> and <NUM> is provided between respective nitride layers (e.g., silicon nitride based layers <NUM>, <NUM>, <NUM>) in order to reduce or prevent oxidation of the IR reflecting layers during possible heat treatment (e.g., thermal tempering, heat bending, and/or heat strengthening) thereby permitting predictable coloration to be achieved following the heat treatment at multiple viewing angles. While <FIG> illustrates a coated article according to an embodiment of this invention in monolithic form, coated articles according to other embodiments of this invention may comprise IG (insulating glass) window units or the like.

Turning back to the <FIG> embodiment, various thicknesses may be used consistent with one or more of the needs discussed herein. According to certain example embodiments of this invention, example thicknesses (in angstroms) and materials for the respective layers of the <FIG> embodiment on the glass substrate <NUM> are as follows in certain example embodiments for achieving desired transmission, reflective coloration, and visible reflectance in combination with a desirably low SF and/or SHGC value(s) and/or a desirably high LSG value (layers are listed in order moving away from the glass substrate <NUM>):.

Table <NUM> above relates to, for example, embodiments where coating <NUM> is designed so that before and/or after any optional heat treatment such as thermal tempering the coated articles realize one, two, three, four, five or all six of: desirable glass side and/or film side reflective visible coloration such as not too red reflective color (e.g., reflective a* color value(s) from -<NUM> to +<NUM>); a desirably low SHGC; desirable visible transmission; thermal stability upon optional HT such as thermal tempering; desirably low En; and/or a desirably high LSG. In certain example embodiments, upper IR reflecting layer <NUM> is physically thicker than lower IR reflecting layer by at least <NUM> angstroms (Å), more preferably by at least <NUM>Å, and sometimes by at least <NUM>Å. It has been found that this thickness difference surprisingly results in the normal emittance being desirably low in combination with reflective * value(s) being desirably neutral and visible reflectance values being desirably low. In certain example embodiments of this invention, center dielectric layer <NUM> is physically thicker than each of dielectric layers <NUM> and <NUM> by at least <NUM> angstroms (Å), more preferably by at least <NUM>Å, and sometimes by at least <NUM>Å, in order to provide for improved coloration and/or reflectance values especially in low visible transmission applications.

Before and/or after any optional heat treatment (HT) such as thermal tempering, in certain example embodiments of this invention coated articles according to the <FIG> embodiment have color/optical characteristics as follows in Table <NUM> (measured monolithically). It is noted that subscript "G" stands for glass side reflective, subscript "T" stands for transmissive, and subscript "F" stands for film side reflective. As is known in the art, glass side (G) means when viewed from the glass side (as opposed to the layer/film side) of the coated article. Film side (F) means when viewed from the side of the coated article on which the coating is provided. Table <NUM> set forth below illustrates certain characteristics of coated articles according to certain example embodiments of this invention after HT such as thermal tempering (monolithically measured for Table <NUM>). The characteristics below in Table <NUM> are in accordance with Illuminant C, <NUM> degree Observer, and are applicable to HT and non-HT coated articles herein, except that the thermal stability data in Table <NUM> relates to HT coated articles and demonstrates the stability upon HT. Glass side reflective and/or film side reflective coloration may be such that coated articles appear neutral colored, blue-green colored, or yellow-green colored in various example embodiments of this invention.

For purposes of example only, Examples <NUM>-<NUM> representing different example embodiments of this invention, as well we Comparative Examples (CE) <NUM>-<NUM>, are set forth below.

Comparative Examples (CEs) <NUM>-<NUM> and Examples <NUM>, <NUM>, and <NUM> were sputter-deposited (as all examples) layer stacks modeled on <NUM> thick clear glass substrates. Examples <NUM>, <NUM> and <NUM> were layer stacks modeled on <NUM> thick green glass substrates. Examples <NUM> and <NUM> were layer stacks modeled on <NUM> thick deep green SMG-III glass substrates. Examples <NUM>, <NUM> and <NUM> were layer stacks modeled on <NUM> thick crystal grey glass substrates. And Examples <NUM>, <NUM> and <NUM> were layer stacks modeled on <NUM> thick grey glass substrates. Thus, Examples <NUM>-<NUM> for instance are essentially the same coating, but on different colored glass substrates <NUM>. Different thicknesses of various layers in the examples are designed for different desired visible transmission applications. The optical measurements are monolithic measurements. Optical data for CEs <NUM>-<NUM> and Examples <NUM>-<NUM> is in accordance with Illuminant C, <NUM> degree Observer, and for Examples <NUM>-<NUM> is in accordance with D65 <NUM> degree Observer, unless indicated otherwise. The silicon nitride layers in each example were doped with about <NUM>% Al. The TiN layers were approximately stoichiometric, and the NiCr layers were <NUM>/<NUM> Ni/Cr, which of course can be nitrided. Layer thicknesses are in angstroms (Å). "L" in Table <NUM> below stand for Layer (e.g., L2 means layer <NUM> shown in <FIG>, L3 means layer <NUM> shown in <FIG>, and so forth). Note that Comparative Examples <NUM>-<NUM> (CEs <NUM>-<NUM>) used TiN, instead of NiCr, for purposes of comparison. It will be shown below that the use of NiCr for layer <NUM> in Examples <NUM>-<NUM> provided for unexpectedly improved optics compared to the use of TiN for layer <NUM> in CEs <NUM>-<NUM>.

Measured monolithically after thermal tempering (HT), the CEs and Examples has the following characteristics.

It can be seen from Table <NUM>, comparing CEs <NUM>-<NUM> with Examples <NUM>-<NUM>, that the use of NiCr in Examples <NUM>-<NUM> (instead of TiN in CEs <NUM>-<NUM>) for layer <NUM> provided for unexpected results. For instance, the film side reflective a* values (a*F) in CEs <NUM>-<NUM> were too red with values of +<NUM>, +<NUM>, and +<NUM>, respectively. The use of NiCr for layer <NUM> in Examples <NUM>-<NUM> (instead of TiN in CEs <NUM>-<NUM>) unexpectedly shifted the film side reflective a* (a*F) values to acceptable values of <NUM> and -<NUM>, respectively, thereby resulting in not too red coatings as viewed from the film side which are more aesthetically pleasing especially in applications such as monolithic window applications. Additionally, the film side visible reflectance values of CEs <NUM>-<NUM> were too high at <NUM>% and <NUM>%, respectively. The use of NiCr for layer <NUM> in Examples <NUM>-<NUM> (instead of TiN in CEs <NUM>-<NUM>) unexpectedly shifted the film side visible reflectance vales to more acceptable and aesthetically pleasing <NUM>% and <NUM>%, respectively. Moreover, the use of TiN for layer <NUM> allowed En to remain in an acceptable range (whereas that would not have occurred if NiCr had been used for both IR reflecting layers <NUM> and <NUM>). It is noted that CEs <NUM>-<NUM> are readily comparable to Examples <NUM>-<NUM> because they have similar visible transmission values.

Measured monolithically after thermal tempering (HT), Examples <NUM>-<NUM> had the following characteristics. Examples <NUM>-<NUM> confirm the unexpected results demonstrated above by using NiCr for layer <NUM> (instead of TiN in CEs <NUM>-<NUM>).

Again, in addition to the comparison above between CEs <NUM>-<NUM> and Examples <NUM>-<NUM>, it can be seen also by comparing Examples <NUM>-<NUM> with CEs <NUM>-<NUM> that the use of NiCr in Examples <NUM>-<NUM> (instead of TiN in CEs <NUM>-<NUM>) for layer <NUM> provided for unexpected results. For instance, the film side reflective a* values (a*F) in CEs <NUM>-<NUM> were too red with values of +<NUM>, +<NUM>, and +<NUM>, respectively. The use of NiCr for layer <NUM> in Examples <NUM>-<NUM> (instead of TiN in CEs <NUM>-<NUM>) unexpectedly shifted the film side reflective a* (a*F) values to acceptable values within the range of -<NUM> to +<NUM>, thereby resulting in not too red coatings as viewed from the film side which are more aesthetically pleasing. Additionally, the film side visible reflectance values of CEs <NUM>-<NUM> were too high at <NUM>% and <NUM>%, respectively. The use of NiCr for layer <NUM> in Examples <NUM>-<NUM> (instead of TiN in CEs <NUM>-<NUM>) unexpectedly shifted the film side visible reflectance vales to more acceptable and aesthetically pleasing values no greater than <NUM>%. Moreover, the use of TiN for layer <NUM> allowed En to remain in an acceptable range (whereas that would not have occurred if NiCr had been used for both IR reflecting layers <NUM> and <NUM>). In Examples <NUM>-<NUM> for example, it can be seen that film side reflective a* color is aesthetically acceptable with a maximum value around +<NUM> (barely red). Overall film side reflective coloration varies between light greenish blue to light violet-blue, while at the same time film side visible reflectance remains desirably low ranging between <NUM>% and <NUM>% regardless of light transmission value. Glass side visible reflectance also remains fairly low across all transmission ranges, and glass side reflective color varies from neutral to blue-green to yellowish green except when placed on grey tinted glass where the has a light gray appearance. These are medium spectrally selective products, with SHGC (NFRC-<NUM>) ranging from about <NUM> for low visible transmission designs to about <NUM> for high visible transmission designs. Normal emissivity varies from about <NUM> and about <NUM>. LSG varies from about <NUM> for a low light transmission design on gray tinted glass to about <NUM> for high light transmission designs on green tinted glass. Thickness and substrate variations of the basic design can be made to achieve other desired transmissions, reflections, reflected color and thermal performance.

With respect to the automotive market, there is a need for privacy glass. Such products are used in the areas of light trucks (trucks, SUV's and cross over vehicles) where light transmission is allowed to be less than <NUM>% behind the B-pillars of the vehicle. This market is supplied today with deep gray body tinted glass. The typical existing automotive privacy glass has a low visible light transmission (typically less than about <NUM>%), very low outdoor reflectance (less than about <NUM>%) as well as a transmitted and reflected color that appears to be a neutral gray. Coated articles according to example embodiments of this invention could be used in vehicle privacy glass applications, without necessarily needing deeply tinted glass substrates. Referring to Examples <NUM>-<NUM> above for example, coatings when deposited on standard green tinted glass (e.g., see Ex. <NUM>) may have a visible light transmission of about <NUM>%, and a glass and film side reflectance of about <NUM>%, transmitted color is blue-green, glass side reflective color is light violet but appears as a blackish gray due to the low reflectance, film side color is a light greenish blue, and with an LSG of about <NUM> the coated article is more spectrally selective than conventional PrivaGuard deep grey body tinted glass conventionally used in such applications. Such applications can be advantageus, for example as green tinted glass substrates typically have a much lower cost to produce than do deeply grey body tinted PrivaGuard tinted glass substrate.

It is noted above that IR reflecting layer <NUM> may be of or include NiCrMo and/or NiCrMoNx in certain example embodiments of this invention. In such embodiments the IR reflecting layer <NUM> may, for example, be of or include C22 and/or a nitride thereof. Table <NUM> below shows an example composition of the NiCrMo-based alloy C22.

Moreover, it is noted above that IR reflecting layer <NUM> may be of or include NiCrMo and/or NiCrMoNx in certain example embodiments of this invention. In such embodiments the IR reflecting layer <NUM> may, for example, be of or include Inconel <NUM> and/or a nitride thereof. Table <NUM> below shows an example composition of the NiCrMo-based alloy Inconel <NUM>.

Claim 1:
A coated article including a coating supported by a glass substrate (<NUM>), the coating comprising:
a first dielectric layer (<NUM>) comprising silicon nitride;
a first infrared (IR) reflecting layer (<NUM>) comprising Ni and Cr on the glass substrate over at least the first dielectric layer comprising silicon nitride;
a second dielectric layer (<NUM>) comprising silicon nitride on the glass substrate over at least the first dielectric layer (<NUM>) comprising silicon nitride and the first IR reflecting layer (<NUM>) comprising Ni and Cr;
a second IR reflecting layer (<NUM>) comprising a nitride of titanium on the glass substrate (<NUM>) over at least the second dielectric layer (<NUM>) comprising silicon nitride;
a third dielectric layer (<NUM>)comprising silicon nitride on the glass substrate (<NUM>) over at least the second IR reflecting layer (<NUM>) comprising the nitride of titanium;
an overcoat (<NUM>) comprising an oxide of zirconium;
wherein the coating contains no IR reflecting layer based on silver; and
wherein the coated article has: a visible transmission from <NUM>-<NUM>%, a glass side visible reflectance no greater than <NUM>%, a film side visible reflectance no greater than <NUM>%, a glass side reflective a* value of from -<NUM> to +<NUM>, and a film side reflective a* color value of from -<NUM> to +<NUM>.