Coated article with IR reflecting layer and method of making same

• US 20090263596A1
• Filed: 04/21/2008
• Published: 10/22/2009
• Est. Priority Date: 04/21/2008
• Status: Active Grant

• Current Assignee: Guardian Glass LLC (KOCH Industries Incorporated)
• Original Assignee: C.R.V.C., Grand Duche De Luxemboug, Guardian Industries Corporation (KOCH Industries Incorporated)
• Inventors: Lingle, Philip J., Blacker, Richard, Disteldorf, Bernd, Boyce, Brent, Lao, Jingyu
• Granted Patent: US 8,409,717 B2
• Time in Patent Office: Days
• US Class Current: 428/34
• CPC Class Codes: B32B 17/06 comprising glass as the main or only constituent of a layer, next to another layer of a specific material
• CPC Class Codes: B32B 2255/20 Inorganic coating
• CPC Class Codes: B32B 2255/28 Multiple coating on one surface
• CPC Class Codes: B32B 2307/304 Insulating
• CPC Class Codes: B32B 2307/412 Transparent
• CPC Class Codes: B32B 2307/416 Reflective
• CPC Class Codes: C03C 17/2453 Coating containing SnO2
• CPC Class Codes: C03C 17/3435 comprising a nitride, oxynitride, boronitride or carbonitride
• CPC Class Codes: C03C 17/36 at least one coating being a metal
• CPC Class Codes: C03C 17/3618 Coatings of type glass/inorganic compound/other inorganic layers, at least one layer being metallic
• CPC Class Codes: C03C 17/3626 one layer at least containing a nitride, oxynitride, boronitride or carbonitride
• CPC Class Codes: C03C 17/3634 one layer at least containing carbon, a carbide or oxycarbide
• CPC Class Codes: C03C 17/3644 the metal being silver
• CPC Class Codes: C03C 17/3652 the coating stack containing at least one sacrificial layer to protect the metal from oxidation
• CPC Class Codes: C03C 17/366 Low-emissivity or solar control coatings
• CPC Class Codes: C03C 17/3681 the multilayer coating being used in glazing, e.g. windows or windscreens
• CPC Class Codes: C03C 2217/21 Oxides
• CPC Class Codes: C03C 2217/211 SnO2
• CPC Class Codes: C03C 2217/212 TiO2
• CPC Class Codes: C03C 2217/216 ZnO
• CPC Class Codes: C03C 2217/219 : CrOx, MoOx, WOx
• CPC Class Codes: C03C 2217/256 : Ag
• CPC Class Codes: C03C 2217/281 : Nitrides
• CPC Class Codes: C03C 2217/70 : Properties of coatings
• CPC Class Codes: C03C 2218/154 : by sputtering
• CPC Class Codes: C03C 2218/156 : by magnetron sputtering
• CPC Class Codes: C23C 14/0652 : Silicon nitride
• CPC Class Codes: C23C 14/086 : of zinc, germanium, cadmium, indium, tin, thallium or bismuth
• CPC Class Codes: E06B 2009/2417 : Light path control; means to control reflection
• CPC Class Codes: E06B 3/6715 : specially adapted for increased thermal insulation or for controlled passage of light E06B3/66323 takes precedence; coating of glass pains C03C17/00; devices or arrangements for controlling the intensity, colour, phase, polarisation or direction of light G02F1/00
• CPC Class Codes: E06B 9/24 : Screens or other constructions affording protection against light, especially against sunshine; Similar screens for privacy or appearance; Slat blindsoperating, guiding or securing devices or arrangements for roll-type closures E06B9/56; free-hanging flexible screens A47H23/00
• CPC Class Codes: Y10T 428/265 : 1 mil or less

Abstract

Example embodiments of this invention relate to a coated article including an infrared (IR) reflecting layer of a material such as silver or the like, for use in an insulating glass (IG) window unit for example. In certain example embodiments, the coating is a single-silver type coating, and includes an overcoat including an uppermost layer of or including silicon nitride and a layer of or including tin oxide immediately under and contacting the silicon nitride based overcoat. In certain example embodiments, the thicknesses of the silicon nitride based overcoat and the tin oxide based layer are balanced (e.g., substantially equal, or equal plus/minus about 10%). It has surprisingly been found that such balancing results in an improvement in thermal cycling performance and improved mechanical durability. In certain example embodiments, the coating may realize surprisingly good substantially neutral film side reflective coloration, and may achieve an improved visible transmission, SHGC ratio and low U-values. Moreover, in certain example embodiments, stress in the overcoat of the coating may be reduced by reducing nitrogen gas flow (N₂ ml/kW) and cathode power during a sputter-deposition process, thereby further improving thermal cycling performance.

Claims

1. A coated article including a coating supported by a glass substrate, the coating comprising:

at least one dielectric layer;

a layer comprising zinc oxide over the at least one dielectric layer;

an infrared (IR) reflecting layer comprising silver on the glass substrate, located over and directly contacting the layer comprising zinc oxide, wherein the coating includes only one IR reflecting layer;

a layer comprising an oxide of Ni and/or Cr located over and directly contacting the IR reflecting layer comprising silver;

an overcoat comprising a layer comprising tin oxide located over the oxide of Ni and/or Cr and a layer comprising silicon nitride located over and contacting the layer comprising tin oxide; and

wherein, in the overcoat, the layer comprising tin oxide and the layer comprising silicon nitride have substantially equal thicknesses plus/minus 15% in order to improve thermal cycling performance and mechanical durability of the coating.

2. The coated article of claim 1, wherein in the overcoat the layer comprising tin oxide has a thickness of from about 80-210 Å

and the layer comprising silicon nitride has a thickness of from about 100-250 Å

.

3. The coated article of claim 1, wherein in the overcoat the layer comprising tin oxide and the layer comprising silicon nitride each have a thickness of from about 160-180 Å

.

4. The coated article of claim 1, wherein the at least one dielectric layer comprises a first layer comprising silicon nitride contacting the glass substrate, a layer comprising titanium oxide over and contacting the first layer comprising silicon nitride, and a second layer comprising silicon nitride over and contacting the layer comprising titanium oxide, and wherein the layer comprising zinc oxide directly contacts the second layer comprising silicon nitride.

5. The coated article of claim 1, wherein the coating has a sheet resistance (R_s) of no greater than 11 ohms/square.

6. The coated article of claim 1, wherein the coating has a sheet resistance (R_s) of no greater than 10 ohms/square.

7. The coated article of claim 1, wherein the coated article is an insulating glass (IG) window unit.

8. The coated article of claim 7, wherein the IG unit has an SHGC value of at least 0.65, a visible transmission of at least 70%, and an Energy Rating of at least 25.

9. The coated article of claim 7, wherein the IG unit has an SHGC value of at least 0.68, a visible transmission of at least 74.5%, and an Energy Rating of at least 29.

10. The coated article of claim 8, wherein the IG unit has a U-value of no greater than 0.30 Btu/h ft F.

11. The coated article of claim 8, wherein the IG unit comprises at least an interior glass substrate and an exterior glass substrate, wherein the coating is provided on a surface of the interior glass substrate facing a gap between the interior and exterior glass substrates, and wherein the IG unit has, as viewed from an exterior of a building in which the IG unit is provided, a reflective a* value of from about −

4 to 0, and a reflective b* value of from about −

1 to +2.5.

12. An IG window unit including a coating supported by a glass substrate, the coating from the glass substrate outwardly comprising:

at least one dielectric layer;

a layer comprising zinc oxide over the at least one dielectric layer;

an infrared (IR) reflecting layer comprising silver on the glass substrate, located over and directly contacting the layer comprising zinc oxide, wherein the coating includes only one IR reflecting layer;

a layer comprising an oxide of Ni and/or Cr located over and directly contacting the IR reflecting layer comprising silver;

an overcoat comprising a layer comprising tin oxide located over the oxide of Ni and/or Cr and a layer comprising silicon nitride located over and contacting the layer comprising tin oxide; and

wherein the IG unit has an SHGC value of at least 0.65, a visible transmission of at least 70%, and an Energy Rating of at least 25.

13. The IG unit of claim 12, wherein the IG unit has an SHGC value of at least 0.68, a visible transmission of at least 74.5%, and an Energy Rating of at least 29.

14. The IG unit of claim 12, wherein the IG unit has a U-value of no greater than 0.30 Btu/h ft F.

15. The IG unit of claim 12, wherein said glass substrate is an interior glass substrate, the IG unit further comprising an exterior glass substrate located adjacent an exterior of a building in which the IG unit is provided, wherein the coating is provided on a surface of the interior glass substrate facing a gap between the interior and exterior glass substrates, and wherein the IG unit has, as viewed from an exterior of the building, a reflective a* value of from about −

4 to 0 and a reflective b* value of from about −

1 to +2.5.

16. A method of making a coated article including a coating provided on a glass substrate, the method comprising:

sputter-depositing at least one dielectric layer and at least one IR reflecting layer over at least the dielectric layer;

sputter-depositing an overcoat on the glass substrate over at least the IR reflecting layer, the overcoat comprising a layer comprising tin oxide and a layer comprising silicon nitride located over and contacting the layer comprising tin oxide; and

when sputter-depositing the layer comprising silicon nitride using a nitrogen gas flow of no greater than 450 sccm, using a cathode power of less than 50 kW, and using a ratio of nitrogen gas flow to cathode power (N₂ ml/kW) of from about 6-10.

17. The method of claim 16, when sputter-depositing the layer comprising silicon nitride using a nitrogen gas flow of no greater than 350 sccm, using a cathode power of less than 45 kW.

18. The method of claim 17, further comprising, when sputter-depositing the layer comprising silicon nitride, using a ratio of nitrogen gas flow to cathode power (N₂ ml/kW) of from about 7 to 9.

19. The method of claim 16, further comprising sputter-depositing the layer comprising tin oxide and the layer comprising silicon nitride so that they have substantially equal thicknesses plus/minus about 15%.

20. The method of claim 16, further comprising, when sputter-depositing the layer comprising silicon nitride, using a combination of at least argon and nitrogen gases, and using an argon gas flow of at least about 300 sccm, more preferably at least about 350 sccm, and most preferably at least about 375 sccm.