Metal based coating composition and related coated substrates

1. A coated substrate comprising:

a. a substrate; and

b. a coating composition over the substrate comprising:

i. at least one metal based layer selected from the group consisting of tungsten, chromium, tantalum, molybdenum, aluminum, alloys of cobalt and chromium, and mixtures thereof, wherein each metal based layer independently has a thickness of from 14 nm to 50 nm; and

ii. at least one dielectric layer comprising Si x N y , where x/y ranges from 0.75 to 1.5, over and adjacent to the metal based layer,

wherein the dielectric layer is a multiple film configuration consisting of,

(i) a first dielectric film comprising Si x N y having an index of refraction,

(ii) a second dielectric film over the first dielectric film, the second dielectric film having an index of refraction that is at least 0.25 lower than the index of refraction of the first dielectric film, where said second dielectric film is silicon dioxide, and

(iii) a third dielectric film comprising Si x N y over the second film.

2. The coated substrate according to claim 1 , wherein the metal based layer comprises an alloy of cobalt and chromium.

3. The coated substrate according to claim 1 , wherein the first and third dielectric films are the same material.

4. The coated substrate according to claim 3 , wherein the first dielectric layer is Si 3 N 4 and the third dielectric layer is Si 3 N 4 .

5. The coated substrate according to claim 4 , wherein the dielectric layer has a thickness of greater than or equal to 5 nm.

6. The coated substrate according to claim 4 , further comprising a layer of titanium nitride, chromium nitride, tungsten nitride or mixtures thereof over the dielectric layer.

7. The coated substrate according to claim 1 , further comprising a protective overcoat as the last layer of the coating stack, the protective overcoat selected from the group consisting of silicon dioxide, zirconium dioxide, titanium dioxide, niobium dioxide, chromium dioxide, silicon oxynitride and mixtures thereof.

8. The coated substrate according to claim 1 , wherein a non-heat treated, coated substrate of claim 1 as compared to a heat treated, coated substrate of claim 1 has a ΔE cmc (1.5:1) (T), a ΔE cmc (1.5:1) (R1) and a ΔE cmc (1.5:1) (R2) no greater than 8 units.

9. The coated substrate according to claim 1 , wherein the substrate is glass.

10. The coated substrate according to claim 9 , wherein the glass substrate is incorporated into an insulating glass unit.

11. The coated substrate according to claim 10 , incorporated into an insulating glass unit, wherein the insulating glass unit exhibits at least one of the following: a visible transmittance of no greater than 90% and an R2 visible light reflectance of greater than 4%.

12. A coated substrate comprising:

a. a first metal based layer selected from the group consisting of tungsten, chromium, tantalum, molybdenum, aluminum, niobium, mixtures thereof; and alloys of cobalt and chromium over a substrate;

b. an infrared reflective layer over the first metal based layer;

c. a second metal based layer selected from tungsten, chromium, tantalum, molybdenum, aluminum, mixtures thereof; and alloys of cobalt and chromium over the infrared reflective layer; and

d. a dielectric layer over the second metal based layer wherein the dielectric layer comprises Si x N y , where x/y ranges from 0.75 to 1.5,

wherein the dielectric layer is a multiple film configuration consisting of,

(i) a first dielectric film comprising Si x N y having an index of refraction,

(ii) a second dielectric film over the first dielectric film, the second dielectric film having an index of refraction that is at least 0.25 lower than the index of refraction of the first dielectric film, where the second dielectric film is silicon dioxide, and

(iii) a third dielectric film comprising Si x N y over the second film,

wherein said first metal based layer and said second metal based layer each independently have a thickness of from 14 nm to 50 nm.

13. A coated substrate according to claim 12 , wherein the infrared reflective layer is selected from the group consisting of gold, copper and silver as well as mixtures and alloys thereof.

14. A coated substrate according to claim 12 , wherein the infrared reflective layer is silver.

15. The coated substrate according to claim 13 , wherein the infrared reflective layer has a thickness ranging from 1 nm to 50 nm.