Heat treatable coated article having titanium nitride and ITO based IR reflecting layers

Abstract

Coated articles include two or more functional infrared (IR) reflecting layers optionally sandwiched between at least dielectric layers. The dielectric layers may be of or including silicon nitride or the like. 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 indium-tin-oxide (ITO).

Claims

1. A coated article including a coating supported by a glass substrate, the coating comprising: a first dielectric layer comprising silicon nitride on the glass substrate; a first infrared (IR) reflecting layer comprising ITO on the glass substrate, wherein the first dielectric layer comprising silicon nitride is located between at least the glass substrate and the first IR reflecting layer comprising ITO; a second dielectric layer comprising silicon nitride on the glass substrate over at least the first IR reflecting layer comprising ITO; a second layer IR reflecting layer comprising a nitride of titanium on the glass substrate over at least the first and second dielectric layers comprising silicon nitride, so that the second dielectric layer comprising silicon nitride is located between at least the first IR reflecting layer comprising ITO and the second IR reflecting layer comprising the nitride of titanium; 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 contains only two IR reflecting layers; wherein the first IR reflecting layer comprising ITO is from 250-450 thick, and the second IR reflecting layer comprising the nitride of titanium is from 130-300 thick; and wherein the coated article measured monolithically has: a visible transmission from about 15-80%, a film side visible reflectance no greater than 10%, a glass side visible reflectance no greater than about 30%, a glass side reflective a* value of from 10.0 to +1.6, and a light-to-solar gain ratio (LSG) of at least 1.10.

2. The coated article of claim 1, wherein the second IR reflecting layer comprising the nitride of titanium comprises TiN.sub.X, where x is from 0.8 to 1.2.

3. The coated article of claim 1, wherein the second IR reflecting layer comprising the nitride of titanium comprises TiN.sub.X, where x is from 0.9 to 1.1.

4. The coated article of claim 1, wherein the second IR reflecting layer contains from 0-8% oxygen (atomic %).

5. The coated article of claim 1, wherein the second IR reflecting layer contains from 0-5% oxygen (atomic %).

6. The coated article of claim 1, wherein the first dielectric layer comprising silicon nitride directly contacts the glass substrate and the first IR reflecting layer.

7. The coated article of claim 6, wherein the first dielectric layer comprising silicon nitride further comprises oxygen.

8. The coated article of claim 1, where the second IR reflecting layer consists essentially of the nitride of titanium.

9. The coated article of claim 1, wherein the coating further comprises an overcoat comprising an oxide of zirconium.

10. The coated article of claim 1, wherein the coated article has a visible transmission from about 20-70%, and a light-to-solar gain ratio (LSG) of at least 1.15.

11. The coated article of claim 1, wherein the coated article has a film side visible reflectance no greater than 5%.

12. The coated article of claim 1, wherein the glass substrate is a clear glass substrate.

13. The coated article of claim 1, wherein the coated article is a monolithic window.

14. A coated article including a coating supported by a glass substrate, the coating comprising: a first infrared (IR) reflecting layer comprising ITO supported by the glass substrate; a dielectric layer comprising silicon nitride on the glass substrate over at least the first IR reflecting layer comprising ITO; a second layer IR reflecting layer comprising a nitride of titanium on the glass substrate over at least the dielectric layer comprising silicon nitride, so that the dielectric layer comprising silicon nitride is located between at least the first IR reflecting layer comprising ITO and the second IR reflecting layer comprising the nitride of titanium; another 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 contains only two IR reflecting layers; and wherein the coating has a normal emittance (E.sub.n) value of no greater than 0.30; wherein the first IR reflecting layer comprising ITO is from 250-450 thick, and the second IR reflecting layer comprising the nitride of titanium is from 130-300 thick.

15. A coated article including a coating supported by a glass substrate, the coating comprising: a first dielectric layer comprising silicon nitride on the glass substrate; a first infrared (IR) reflecting layer comprising ITO on the glass substrate, wherein the first dielectric layer comprising silicon nitride is located between at least the glass substrate and the first IR reflecting layer comprising ITO; a second dielectric layer comprising silicon nitride on the glass substrate over at least the first IR reflecting layer comprising ITO; a second layer IR reflecting layer comprising a nitride of titanium on the glass substrate over at least the first and second dielectric layers comprising silicon nitride, so that the second dielectric layer comprising silicon nitride is located between at least the first IR reflecting layer comprising ITO and the second IR reflecting layer comprising the nitride of titanium; 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 contains only two IR reflecting layers; wherein the first IR reflecting layer comprising ITO is from 250-450 thick, and the second IR reflecting layer comprising the nitride of titanium is from 130-300 thick; and wherein the coated article measured monolithically has a visible transmission from about 15-80%.

Description

IN THE DRAWINGS

(1) FIG. 1 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.

DETAILED DESCRIPTION OF CERTAIN EXAMPLE EMBODIMENTS OF THE INVENTION

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

(3) A coating 8 is designed so as to have a combination of acceptable visible transmission (TY or T.sub.vis), desirable glass side reflective coloration (e.g., desirable a* and b* reflective color values), low film side visible reflectance, 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 SHGC will also increase, and E.sub.n 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.

(4) Certain embodiments of this invention relate to coated articles having a coating 8 on a glass substrate 1, where the coating includes two or more functional infrared (IR) reflecting layers 3 and 5 which may be sandwiched between at least transparent dielectric layers 2, 4, 6, 7, and/or a method of making the same. Some of the transparent dielectric layers, such as dielectric layer(s) 2 and/or 7, are optional and need not be provided in certain example embodiments. The dielectric layers 2, 4 and 6 are preferably amorphous, preferably have a k<0.1, and may be of or include silicon nitride, silicon oxynitride, zinc stannate, tin oxide, or the like. Transparent dielectric overcoat 7, of or including zirconium oxide or any other suitable material, is optional. In certain 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 ITO. In the FIG. 1 embodiment, upper IR reflecting layer 5 is of or including titanium nitride (e.g., TiN) and lower IR reflecting layer 3 is of or including ITO. It has surprisingly and unexpectedly been found that the use of these different materials for the different IR reflecting layers 3 and 5 (e.g., as opposed to using TiN for both IR reflecting layers 3 and 5) in a given solar control coating surprisingly results in improved optics such as improved glass side reflective a* values and/or higher LSG values which are often desirable characteristics in window applications, and the provision of the IR reflecting 3 layer of or including ITO allows coated articles to be more easily tailored for desired visible transmission values and high LSG values while the IR reflecting layer of or including TiN 5 provides for desirably low normal emissivity and/or SHGC values for a given thickness of IR reflecting material. Coating 8 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 reflective visible coloration that is not too red (e.g., reflective a* color value(s) from 8 to +1.6); a desirably low solar heat gain coefficient (SHGC); desirable visible transmission (TY or T.sub.vis); low film side reflectance; thermal stability upon optional heat treatment (HT) such as thermal tempering; desirably low E.sub.n; and/or a desirably high light-to-solar gain ratio (LSG). In example embodiments of this invention, the coating 8 contains no IR reflecting layer based on Ag or Au.

(5) In certain example embodiments of this invention, certain applications such as monolithic window applications desire glass side reflective coloration that is not significantly red. In other words, certain applications such as monolithic window applications desire glass side reflective a* color values that are either negative or no greater than +1.6 (glass side reflective a* values higher than +1.6 are undesirably red). Such glass side reflective a* values are not too red and are desirable in the context of glass side reflective (R.sub.GY) a* values.

(6) 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 580 degrees C., more preferably at least about 600 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 4 or 5 minutes. The coated article may or may not be heat treated in different embodiments of this invention. Instead of HT at >600 C (e.g., tempering), this coating can also achieve desired performance by activating HT at as low as 350 degrees C. for example. After HT at 350 C for example, the glass is not tempered and may be cut to desired size.

(7) FIG. 1 is a cross sectional view of a coated article according to an example embodiment of this invention. In the FIG. 1 embodiment the solar control coating 8 includes two IR reflecting layers 3 and 5, and transparent dielectric layers 2, 4, 6 and 7. The coated article includes at least glass substrate 1 (e.g., clear, green, bronze, grey, blue, or blue-green glass substrate from about 1.0 to 12.0 mm thick, more preferably from 4-8 mm thick, with an example glass substrate thickness being 6 mm), transparent dielectric layers 2, 4, 6 (e.g., of or including silicon nitride [e.g., Si.sub.3N.sub.4], silicon oxynitride, silicon zirconium nitride, or some other suitable dielectric), and IR reflecting layers 3, 5. Upper IR reflecting layer 5 is of or including titanium nitride (e.g., TiN, preferably a stoichiometric or substantially stoichiometric type) and lower IR reflecting layer 3 is of or including conductive ITO. The upper IR reflecting layer 5 is of or includes TiN.sub.x in certain example embodiments of this invention, where x is preferably from 0.8 to 1.2, more preferably from 0.9 to 1.1, with an example value being about 1.0. These x values provide for improved/lowered emittance values compared to if x is too low for instance. The titanium nitride has been found to be very durable compared to silver for example, and more resistant to moisture induced corrosion compared to silver for example. It has surprisingly and unexpectedly been found that the use of these different materials for the different IR reflecting layers 3 and 5 (e.g., as opposed to using TiN for both IR reflecting layers 3 and 5) in a given solar control coating provides for surprisingly results as explained herein. While the IR reflecting layer 5 may include some small amount of oxygen in certain instances, it is preferable that layer 5 is substantially free of oxygen such as no more than 8% oxygen, more preferably no more than about 5% oxygen, and most preferably no more than about 3% or 2% oxygen in certain embodiments (atomic %). While IR reflecting layer 5 is of or including titanium nitride in preferred embodiments of this invention, it is possible for upper IR reflecting layer 5 to be of another metal nitride such as zirconium nitride and/or niobium nitride in alternative embodiments of this invention. The coated article may optionally include transparent dielectric overcoat layer 7 of or including a protective material such as zirconium oxide (e.g., ZrO.sub.2) or silicon oxynitride. 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 6 and 7 in the upper part of the layer stack in certain example embodiments. In certain example embodiments of this invention, coating 8 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 3 and 5 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. It will be appreciated of course that other layers may also be provided, or certain layers may be omitted, and different materials may be used, in certain alternative embodiments of this invention. For example, another metal nitride layer 5 could be added above the ITO in certain alternative embodiments of this invention.

(8) The overall coating 8 of FIG. 1 includes at least the illustrated layers in certain example embodiments, with layers 2 and 7 in particular being optional. 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 2, 4, 6) includes stoichiometric Si.sub.3N.sub.4, 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 1 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. 1 such as between layers 2 and 3, or between layers 3 and 4, or between the substrate 1 and layer 2, or the like. Generally, other layer(s) may also be provided in other locations of the coating. Thus, while the coating 8 or layers thereof is/are on or supported by substrate 1 (directly or indirectly), other layer(s) may be provided therebetween. Thus, for example, the layer system 8 and layers thereof shown in FIG. 1 are considered on the substrate 1 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. 1 in preferred embodiments.

(9) In certain example embodiments of this invention, dielectric layers 2, 4, and 6 may each have an index of refraction n of from 1.7 to 2.5 (at 550 nm), more preferably from 1.8 to 2.2 in certain embodiments, and most preferably from about 2.0 to 2.06 in preferred embodiments of this invention. One, two, three, or all of these layers 2, 4, 6 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 2, 4, 6 comprise silicon nitride (e.g., Si.sub.3N.sub.4) or silicon oxynitride, sputtering targets including Si employed to form these layers may or may not be admixed with up to 1-20% (e.g., 8%) by weight aluminum or stainless steel (e.g. SS #316), 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 certain example embodiments, each of the IR reflecting layers 3 and 5 is provided between respective nitride layers (e.g., silicon nitride based layers 2, 4, 6) in order to reduce or prevent damage to 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. 1 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.

(10) Turning back to the FIG. 1 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. 1 embodiment on the glass substrate 1 are as follows in certain example embodiments for achieving desired transmission, glass side reflective coloration, and visible reflectance in combination with a desirably low SHGC value(s) and/or a desirably high LSG value (layers are listed in order moving away from the glass substrate 1):

(11) TABLE-US-00001 TABLE 1 (Thicknesses in FIG. 1 embodiment) Example Preferred Example Layer Range () () () silicon nitride (layer 2): 20-500 40-200 50 IR reflector (e.g., ITO) (layer 3): 100-1,000 250-450 330 silicon nitride (layer 4): 20-1100 25-400 300 IR reflector (e.g., TiN) (layer 5): 50-450 130-300 200 silicon nitride (layer 6): 20-800 300-550 450 overcoat (e.g., ZrO.sub.2) (layer 7): 10-150 20-40 30

(12) Table 1 above relates to, for example, embodiments where coating 8 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, six or all seven of: desirable glass side reflective visible coloration such as not too red reflective color (e.g., reflective a* color value(s) from 8 to +1.6); a desirably low SHGC; desirable visible transmission; low film side visible reflectance, thermal stability upon optional HT such as thermal tempering; desirably low E.sub.n; and/or a desirably high LSG. In certain example embodiments, lower IR reflecting layer 5 may be physically thicker than upper IR reflecting layer by at least 50 angstroms (), more preferably by at least 100 . In certain example embodiments of this invention, upper dielectric layer 6 is physically thicker than center dielectric layer 4 by at least 50 angstroms (), more preferably by at least 100 , and sometimes by at least 150 .

(13) 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. 1 embodiment have color/optical characteristics as follows in Table 2 (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. The characteristics below in Table 2 are in accordance with Illuminant C, 2 degree Observer, and are applicable to HT and non-HT coated articles herein. Glass 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.

(14) TABLE-US-00002 TABLE 2 Color/Optical Characteristics (FIG. 1 embodiment monolithic) General Preferred Most Preferred T.sub.vis (TY): 15-80% 20-70% 30-60% (or 40-60%) a*.sub.T 10 to +5 8 to +2 6 to 0 b*.sub.T 15 to +7 10 to +3 9 to 0 R.sub.GY(glass side): 30% 25% 20% a*.sub.G 10 to +1.6 8 to +1.6 6 to +1 b*.sub.G 25 to +9 9 to +4 8 to +1 R.sub.FY(film side): 10% 8% 5% a*.sub.F 9 to +9 6 to +7 3 to +5 b*.sub.F 14 to +9 9 to +4 8 to 0 E.sub.n: 0.30 0.25 0.22 SHGC: 0.52 0.45 0.42 LSG: 1.10 1.15 1.22

(15) For purposes of example only, Example 1 representing an example embodiments of this invention, as well we Comparative Examples (CE) 1-5, are set forth below.

EXAMPLES

(16) Comparative Examples (CEs) 1-4 and Examples 1-2 were sputter-deposited (as all examples) layer stacks modeled on 4 mm thick clear glass substrates. And CE 5 was a layer stacks modeled on 4 mm thick green glass substrate. The optical measurements are monolithic measurements. Optical data for CEs 1-5 and Examples 1-2 is in accordance with Illuminant C, 2 degree Observer. The silicon nitride layers were doped with about 8% Al. The TiN layers were approximately stoichiometric. Layer thicknesses are in angstroms (). L in Table 4 below stand for Layer (e.g., L2 means layer 2 shown in FIG. 1, L3 means layer 3 shown in FIG. 1, and so forth). It will be shown below that the use of ITO for layer 3 in Examples 1-2 provided for unexpectedly improved optics compared to the use of TiN or NiCr for layer 3 in CEs 1-5.

(17) TABLE-US-00003 TABLE 3 Layer Stacks of Comparative Examples (CEs) 1-5 Example L2(Si.sub.3N.sub.4) L3(NiCr) or L3(TiN) L4(Si.sub.3N.sub.4) L5(TiN) L6(Si.sub.3N.sub.4) L7(ZrO.sub.2) CE 1: 220 n/a 240 670 310 10 40 CE 2: 140 n/a 200 590 240 30 40 CE 3: 40 n/a 180 350 120 30 40 CE 4: 50 68 n/a 723 268 171 30 CE 5: 50 66 n/a 714 261 206 30

(18) Measured monolithically after thermal tempering (HT), the CEs had the following characteristics.

(19) TABLE-US-00004 TABLE 4 Measured Monolithic Optical Data (CEs 1-5) Parameter CE 1 CE 2 CE 3 CE4 CE5 T.sub.vis (TY)(transmission ): 18.6% 24.2% 35.3% 23.1% 21.8% L*.sub.T: 50.2 56.3 66.0 55.2 53.8 a*.sub.T 7.2 7.0 5.5 3.15 5.86 b*.sub.T 4.3 1.5 0.8 8.27 7.97 R.sub.GY(glass side refl. %): 9.5% 9.2% 13.0% 12.0% 9.6% L*.sub.G: 36.9 36.4 42.8 41.2 37.1 a*.sub.G: 3.2 2.8 0.3 0.8 1.45 b*.sub.G: 3.5 0.4 5.7 1.8 2.1 R.sub.FY(film side refl. %): 25.2% 19.1% 10.8% 14.1% 11.2% L*.sub.F: 57.3 50.8 39.2 44.4 39.9 a*.sub.F: 5.3 4.7 7.0 0.6 0.3 b*.sub.F: 8.3 6.1 5.4 4.9 4.1 E.sub.n: 0.18 0.25 0.36 0.25 0.25 SHGC (NFRC-2001): 0.21 0.24 0.31 0.28 0.27 LSG: 0.80 1.01 1.14 0.83 0.81

(20) Examples 1-2 according to examples of this invention had the following layer stack. Layer thicknesses are in angstroms ().

(21) TABLE-US-00005 TABLE 5 Layer Stack of Examples 1-2 Example L3(ITO) L4(Si.sub.3N.sub.4) L5(TiN) L6(Si.sub.3N.sub.4) L7(Si.sub.3N.sub.4) Ex. 1: 330 300 200 450 n/a Ex. 2: 330 20 180 350 40

(22) Measured monolithically after HT, Examples 1-2 had the following characteristics.

(23) TABLE-US-00006 TABLE 6 Measured Monolithic Optical Data (Examples 1-2) Parameter Example 1 Example 2 T.sub.vis (TY)(transmission ): 51.97% 54.4% a*.sub.T 3.14 3.2 b*T 2.81 3.9 R.sub.GY(glass side refl. %): 19.9% 16.0% a*.sub.G: 4.0 2.1 b*.sub.G: 0.9 0.0 R.sub.FY(film side refl. %): 2.2% 2.6% a*.sub.F: +3.35 +5.6 b*.sub.F: 4.71 +1.8 E.sub.n: 0.20 0.22 SHGC (NFRC-2001): 0.41 0.42 LSG: 1.25 1.30

(24) An advantage of using ITO and TiNx for the IR reflecting layers, instead of using TiNx for both IR reflecting layers, is improved thermal performance such as improved E.sub.n and/or LSG value(s). This is shown in the tables above. It can be seen by comparing CEs 1-5 (Tables 3-4) with Examples 1-2 (Tables 5-6), that the use of ITO in Examples 1-2 (instead of TiN or NiCr in CEs 1-5) for layer 3 provided for unexpected results. For instance, the LSG values of CEs 1, 4 and 5 were all well less than 1.0, which is undesirable. And while the LSG values of CEs 2 and 3 were more acceptable, but still low, at 1.01 and 1.14, these CEs 2 and 3 along with the other CEs had undesirably high film side reflectance of 10.8% or higher. And CE 3 had an undesirably high normal emittance/emissivity (E.sub.n) of 0.36, which means that insufficient IR is blocked by the coating. Thus, for instance, all CEs had undesirably high film side reflectance values, and most had undesirably low LSG values. No comparative example (CE) has a sufficiently low normal emittance/emissivity (E.sub.n) combined with desirably low film side visible reflectance and desirably high LSG.

(25) The use of ITO for layer 3 in Example 1 (instead of TiN or NiCr in CEs 1-5) unexpectedly reduced the film side visible reflectance vales to more acceptable and aesthetically pleasing 2.2% and 2.6% and surprisingly increased the LSG value to 1.25 and 1.30 which means a significant energy saving. Moreover, the use of TiN for layer 5 and ITO for layer 3 allowed normal emittance (E.sub.n) to remain in an acceptable range of no greater than 0.30, more preferably no greater than 0.25, and most preferably no greater than 0.22.

(26) In an example embodiment of this invention, there is provided a coated article including a coating supported by a glass substrate, the coating comprising: a first infrared (IR) reflecting layer comprising ITO on the glass substrate; a first dielectric layer comprising silicon nitride on the glass substrate over at least the first IR reflecting layer comprising ITO; a second layer IR reflecting layer comprising a nitride of titanium on the glass substrate over at least the first dielectric layer comprising silicon nitride, so that the first dielectric layer comprising silicon nitride is located between at least the first IR reflecting layer comprising ITO and the second IR reflecting layer comprising the nitride of titanium; a second 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; wherein the coating has a normal emittance (E.sub.n) value of no greater than 0.30; and wherein the coated article has: a visible transmission from about 15-80%, a film side visible reflectance no greater than 10%, a glass side visible reflectance no greater than about 30%, a glass side reflective a* value of from 10.0 to +1.6, and a light-to-solar gain ratio (LSG) of at least 1.10.

(27) In the coated article of the immediately preceding paragraph, the coating in some instances contains only two IR reflecting layers.

(28) In the coated article of any of the preceding two paragraphs, the first dielectric layer comprising silicon nitride may be located between and directly contacting the first and second IR reflecting layers.

(29) In the coated article of any of the preceding three paragraphs, the second IR reflecting layer comprising the nitride of titanium may comprise TiN.sub.x, where x is from 0.8 to 1.2, more preferably from 0.9 to 1.1.

(30) In the coated article of any of the preceding four paragraphs, the second IR reflecting layer may contain from 0-8% oxygen (atomic %), more preferably from 0-5% oxygen (atomic %).

(31) In the coated article of any of the preceding five paragraphs, the coating may further comprise another dielectric layer comprising silicon nitride or silicon oxynitride located between and contacting the glass substrate and the first IR reflecting layer.

(32) In the coated article of any of the preceding six paragraphs, the second IR reflecting layer may consist essentially of the nitride of titanium.

(33) In the coated article of any of the preceding seven paragraphs, the coating may further comprise an overcoat comprising an oxide of zirconium.

(34) In the coated article of any of the preceding eight paragraphs, the coated article may have a visible transmission from about 20-70% and/or a light-to-solar gain ratio (LSG) of at least 1.15.

(35) In the coated article of any of the preceding nine paragraphs, the coated article may have a light-to-solar gain ratio (LSG) of at least 1.22.

(36) In the coated article of any of the preceding ten paragraphs, the coated article may have a film side visible reflectance no greater than 8%, more preferably no greater than 5%.

(37) In the coated article of any of the preceding eleven paragraphs, the glass substrate may be a clear glass substrate.

(38) In the coated article of any of the preceding twelve paragraphs, the coated article may have a glass side reflective a* value of from 8 to +1.0, and/or a film side reflective a* value of from 9 to +9.

(39) In the coated article of any of the preceding thirteen paragraphs, one or more of the dielectric layers comprising silicon nitride may further comprise oxygen and/or may be doped with aluminum.

(40) In the coated article of any of the preceding fourteen paragraphs, the coated article may be a monolithic window.

(41) In the coated article of any of the preceding fifteen paragraphs, the coated article measured monolithically may have an SHGC value of no greater than 0.52, more preferably no greater than 0.45, and most preferably no greater than 0.42.

(42) In the coated article of any of the preceding sixteen paragraphs, the first IR reflecting layer comprising ITO may be from 100-1,000 thick, and/or the second IR reflecting layer comprising the nitride of titanium may be from 50-450 thick.

(43) In the coated article of any of the preceding seventeen paragraphs, the first IR reflecting layer comprising ITO may be from 250-450 thick, and/or the second IR reflecting layer comprising the nitride of titanium may be from 130-300 thick.

(44) In an example embodiment of this invention, there is provided a coated article including a coating supported by a glass substrate, the coating comprising: a first infrared (IR) reflecting layer comprising ITO on the glass substrate; a first dielectric layer on the glass substrate over and directly contacting the first IR reflecting layer comprising ITO; a second layer IR reflecting layer comprising a metal nitride on the glass substrate over and directly contacting the first dielectric layer, so that the first dielectric layer is located between and directly contacting the first IR reflecting layer comprising ITO and the second IR reflecting layer comprising the metal nitride; a second dielectric layer on the glass substrate over and directly contacting the second IR reflecting layer comprising the metal nitride; wherein the coating contains no IR reflecting layer based on silver; and wherein the coated article has a visible transmission from about 15-80%.

(45) In the coated article of the immediately preceding paragraph, the coating may have a normal emittance (E.sub.n) value of no greater than 0.30, more preferably no greater than 0.25, and most preferably no greater than 0.22.

(46) In the coated article of any of the preceding two paragraphs, the metal nitride may be a nitride of titanium.

(47) In the coated article of any of the preceding three paragraphs, the first and/or second dielectric layer may comprise silicon nitride.

(48) In the coated article of any of the preceding four paragraphs, the coated article may have a film side visible reflectance no greater than 10%, a glass side visible reflectance no greater than about 30%, a glass side reflective a* value of from 10.0 to +1.6, and a light-to-solar gain ratio (LSG) of at least 1.10.

(49) In the coated article of any of the preceding five paragraphs, the second IR reflecting layer may contain from 0-8% oxygen (atomic %), more preferably from 0-5% oxygen (atomic %).

(50) In the coated article of any of the preceding six paragraphs, the coating may further comprise another dielectric layer which may comprise silicon nitride and/or silicon oxynitride located between and contacting the glass substrate and the first IR reflecting layer.

(51) In the coated article of any of the preceding seven paragraphs, the coating may further comprise an overcoat comprising an oxide of zirconium.

(52) In the coated article of any of the preceding eight paragraphs, the coated article may have a visible transmission from about 20-70% and/or a light-to-solar gain ratio (LSG) of at least 1.15.

(53) In the coated article of any of the preceding nine paragraphs, the coated article may have a light-to-solar gain ratio (LSG) of at least 1.22.

(54) In the coated article of any of the preceding ten paragraphs, the coated article may have a film side visible reflectance no greater than 8%, more preferably no greater than 5%.

(55) In the coated article of any of the preceding eleven paragraphs, the glass substrate may be a clear glass substrate.

(56) In the coated article of any of the preceding twelve paragraphs, the coated article may have a glass side reflective a* value of from 8 to +1.0, and/or a film side reflective a* value of from 9 to +9.

(57) Once given the above disclosure many other features, modifications and improvements will become apparent to the skilled artisan. Such other features, modifications and improvements are therefore considered to be a part of this invention, the scope of which is to be determined by the following claims: