Coated article with low-E coating having zinc stannate based layer between IR reflecting layers for reduced mottling and corresponding method
View Patent ↗A coated article is provided which may be heat treated (e.g., thermally tempered) and/or heat bent in certain example instances. In certain example embodiments, a zinc stannate based layer is provided between a tin oxide based layer and a silicon nitride based layer, and this has been found to significantly reduce undesirable mottling damage upon heat treatment/bending. This results in significantly improved bendability of the coated article in applications such as vehicle windshields and the like.
1. A method of making a vehicle windshield, the method comprising:
having or providing a coating on a glass substrate, the coating comprising first and second layers comprising silver with at least the following layers therebetween moving away from the glass substrate: a contact layer over and contacting the first layer comprising silver, a layer comprising tin oxide over at least the contact layer, a layer comprising zinc stannate over and contacting the layer comprising tin oxide, a layer comprising silicon nitride over at least the layer comprising zinc stannate, and a layer comprising zinc oxide over at least the layer comprising silicon nitride; and
heat bending the glass substrate with the coating thereon to an extent so as to have a centerline convex value “x” of at least about 28 mm without experiencing significant mottling damage due to the heat bending.
2. The method of claim 1 , wherein said heat bending is performed so that after said heat bending the coated article has a visible transmission of at least about 75% and a sheet resistance (R s ) of less than or equal to 3.0 ohms/square.
3. The method of claim 1 , wherein the contact layer comprising an oxide of Ni and/or Cr.
4. The method of claim 1 , wherein the layer comprising zinc oxide is over and contacting the layer comprising silicon nitride.
5. The method of claim 1 , wherein the second layer comprising silver is over and contacting the layer comprising zinc oxide.
6. The method of claim 1 , wherein said heat bending is performed so that after said heat bending and after laminating the glass substrate to another glass substrate the coated article comprises a vehicle windshield, and wherein the vehicle windshield as a glass side reflective a* color of from −2.5 to +2.5, and glass side reflective b* color of from −15.0 to 0.
7. The method of claim 1 , further comprising heat bending the glass substrate with the coating thereon to an extent so as to have a centerline convex value “x” of at least about 30 mm without experiencing significant mottling damage due to the heat bending.
8. The method of claim 1 , further comprising heat bending the glass substrate with the coating thereon to an extent so as to have a centerline convex value “x” of at least about 32 mm without experiencing significant mottling damage due to the heat bending.
9. The method of claim 1 , wherein the layer comprising tin oxide is located over and contacting the contact layer.
10. The method of claim 1 , wherein the layer comprising zinc stannate is located between and contacting the layer comprising silicon nitride and the layer comprising tin oxide.
11. The method of claim 1 , wherein the layer comprising tin oxide consists essentially of tin oxide.
12. The method of claim 11 , wherein the layer comprising zinc stannate consists essentially of zinc stannate.
13. The method of claim 1 , wherein the coating further comprises another layer comprising zinc oxide located directly under and contacting the first layer comprising silver.
14. The method of claim 13 , wherein the coating further comprises another layer comprising silicon nitride located directly under and contacting the another layer comprising zinc oxide.
15. The method of claim 1 , wherein the coating further comprises a layer comprising an oxide of NiCr over and directly contacting the second layer comprising silver.
16. The method of claim 1 , wherein the coating further comprises another layer comprising tin oxide and another layer comprising silicon nitride located over the second layer comprising silver.
17. A method of making a coated article, the method comprising:
heat treating a glass substrate with a coating thereon, the coating comprising first and second layers comprising silver with at least a layer comprising zinc stannate therebetween, wherein the layer comprising zinc stannate is provided between at least a layer comprising tin oxide and a layer comprising silicon nitride, wherein the layer comprising zinc stannate is located over and contacting the layer comprising tin oxide; and
heat bending the glass substrate with the coating thereon without experiencing significant mottling damage due to the heat bending.
18. The method of claim 17 , further comprising heat bending the glass substrate with the coating thereon to an extent so as to have a centerline convex value “x” of at least about 28 mm without experiencing significant mottling damage due to the heat bending.
19. The method of claim 17 , further comprising heat bending the glass substrate with the coating thereon to an extent so as to have a centerline convex value “x” of at least about 30 mm without experiencing significant mottling damage due to the heat bending.
20. The method of claim 17 , wherein said heat bending is performed so that after said heat bending the coated article has a visible transmission of at least about 75% and a sheet resistance (R s ) of less than or equal to 3.0 ohms/square.
21. The method of claim 17 , wherein said heat bending is performed so that after said heat bending and after laminating the glass substrate to another glass substrate the coated article comprises a vehicle windshield, and wherein the vehicle windshield as a glass side reflective a* color of from −2.5 to +2.5, and glass side reflective b* color of from −15.0 to 0.
22. The method of claim 17 , wherein the layer comprising zinc stannate is located directly under and contacting the layer comprising silicon nitride.
23. The method of claim 17 , wherein the layer comprising tin oxide consists essentially of tin oxide, and the layer comprising zinc stannate consists essentially of zinc stannate.