Protective layers for optical coatings
View Patent ↗An optical coating on a transparent substrate is provided with a temporary layer of carbon as protection during manufacturing against scratches and corrosive environments. When the optical coating and/or substrate are tempered in an atmosphere reactive to carbon, such as air, the layer of carbon is removed as a carbon-containing gas. For an optical coating with a brittle, glassy, outermost layer furthest from the substrate, additional protection is provided by a scratch propagation blocker layer between the outermost layer and the carbon protective layer.
1. A transparent article comprising
a transparent substrate;
an optical coating comprising one or more layers on the substrate, where the one or more layers include furthest from the substrate a homogeneous outermost layer comprising amorphous silicon nitride; and
a protective coating on the outermost layer, wherein
the protective coating consists of
a scratch propagation blocker layer on the outermost layer, and
a layer consisting essentially of carbon on the scratch propagation blocker layer; and
the scratch propagation blocker layer is a homogeneous layer comprising a material selected from the group consisting of
Ti, Zr, Cr, Nb, Hf, and Ta;
oxides of Ti, Zr, Cr, Nb, Hf, and Ta;
nitrides of Ti, Zr, Cr, Nb, Hf, and Ta;
oxynitrides of Ti, Zr, Cr, Nb, Hf, and Ta; and
mixtures thereof.
2. The transparent article according to claim 1 , wherein the substrate comprises a glass.
3. The transparent article according to claim 2 , wherein the substrate comprises a tempered glass.
4. The transparent article according to claim 1 , wherein the optical coating is a low-emissivity coating.
5. The transparent article according to claim 1 , wherein the optical coating is a tempered coating.
6. The transparent article according to claim 1 , wherein the optical coating contains at least one layer comprising Ag.
7. The transparent article according to claim 1 , wherein the fracture toughness of the scratch propagation blocker layer is higher than the fracture toughness of the outermost layer.
8. The transparent article according to claim 1 , wherein the scratch propagation blocker layer is from 2 to 8 nm thick.
9. The transparent article according to claim 8 , wherein the scratch propagation blocker layer comprises a material selected from the group consisting of oxides of Ti, Zr, Cr, Nb, Hf, and Ta.
10. The transparent article according to claim 8 , wherein the scratch propagation blocker layer comprises a material selected from the group consisting of oxynitrides of Ti, Zr, Cr, Nb, Hf, and Ta.
11. The transparent article according to claim 1 , wherein the layer consisting essentially of carbon is doped with nitrogen.
12. The transparent article according to claim 1 , wherein the layer consisting essentially of carbon consists of carbon and unavoidable impurities.
13. The transparent article according to claim 1 , wherein the carbon in the layer consisting essentially of carbon comprises at least one form of carbon selected from the group consisting of diamond-like carbon and graphite.
14. The transparent article according to claim 1 , wherein the layer consisting essentially of carbon is from 1 to 10 nm thick.
15. A transparent article comprising
a transparent substrate;
an optical coating comprising one or more layers on the substrate, where the one or more layers include furthest from the substrate a homogeneous outermost layer comprising silicon nitride; and
a protective coating on the outermost layer, wherein
the protective coating consists of
a scratch propagation blocker layer on the outermost layer, and
a layer consisting essentially of carbon on the scratch propagation blocker layer; and
the scratch propagation blocker layer is a homogeneous layer 2 to 8 nm thick comprising a material selected from the group consisting of
Ti, Zr, Cr, Nb, Hf, and Ta;
oxides of Ti, Zr, Cr, Nb, Hf, and Ta;
nitrides of Ti, Zr, Cr, Nb, Hf, and Ta;
oxynitrides of Ti, Zr, Cr, Nb, Hf, and Ta; and
mixtures thereof.
16. The transparent article according to claim 15 , wherein the substrate comprises a glass.
17. The transparent article according to claim 16 , wherein the substrate comprises a tempered glass.
18. The transparent article according to claim 15 , wherein the optical coating is a low-emissivity coating.
19. The transparent article according to claim 15 , wherein the optical coating is a tempered coating.
20. The transparent article according to claim 15 , wherein the optical coating contains at least one layer comprising Ag.
21. The transparent article according to claim 15 , wherein the fracture toughness of the scratch propagation blocker layer is higher than the fracture toughness of the outermost layer.
22. The transparent article according to claim 15 , wherein the scratch propagation blocker layer comprises a material selected from the group consisting of oxides of Ti, Zr, Cr, Nb, Hf, and Ta.
23. The transparent article according to claim 15 , wherein the scratch propagation blocker layer comprises a material selected from the group consisting of oxynitrides of Ti, Zr, Cr, Nb, Hf, and Ta.
24. The transparent article according to claim 15 , wherein the layer consisting essentially of carbon is doped with nitrogen.
25. The transparent article according to claim 15 , wherein the layer consisting essentially of carbon consists of carbon and unavoidable impurities.
26. The transparent article according to claim 15 , wherein the carbon in the layer consisting essentially of carbon comprises at least one form of carbon selected from the group consisting of diamond-like carbon and graphite.
27. The transparent article according to claim 15 , wherein the layer consisting essentially of carbon is from 1 to 10 nm thick.
28. A transparent article comprising
a transparent substrate;
an optical coating comprising one or more layers on the substrate, where the one or more layers include furthest from the substrate a homogeneous outermost layer comprising silicon nitride; and
a protective coating on the outermost layer, wherein
the protective coating consists of a scratch propagation blocker layer on the outermost layer; and
the scratch propagation blocker layer is a homogeneous layer comprising a material selected from the group consisting of
Ti, Zr, Cr, Nb, Hf, and Ta;
oxides of Ti, Zr, Cr, Nb, Hf, and Ta;
nitrides of Ti, Zr, Cr, Nb, Hf, and Ta;
oxynitrides of Ti, Zr, Cr, Nb, Hf, and Ta; and
mixtures thereof.
29. The transparent article according to claim 28 , wherein the substrate comprises a glass.
30. The transparent article according to claim 29 , wherein the substrate comprises a tempered glass.
31. The transparent article according to claim 28 , wherein the optical coating is a low-emissivity coating.
32. The transparent article according to claim 28 , wherein the optical coating is a tempered coating.
33. The transparent article according to claim 28 , wherein the optical coating contains at least one layer comprising Ag.
34. The transparent article according to claim 28 , wherein the outermost layer comprises amorphous silicon nitride.
35. The transparent article according to claim 28 , wherein the fracture toughness of the scratch propagation blocker layer is higher than the fracture toughness of the outermost layer.
36. The transparent article according to claim 28 , wherein the scratch propagation blocker layer is from 2 to 8 nm thick.
37. The transparent article according to claim 36 , wherein the scratch propagation blocker layer comprises a material selected from the group consisting of oxides of Ti, Zr, Cr, Nb, Hf, and Ta.
38. The transparent article according to claim 36 , wherein the scratch propagation blocker layer comprises a material selected from the group consisting of oxynitrides of Ti, Zr, Cr, Nb, Hf, and Ta.
39. The transparent article according to claim 28 , wherein the scratch propagation blocker layer is in contact with air.
40. The transparent article according to claim 1 , wherein the scratch propagation blocker layer is from 2 to 8 nm thick; and
the layer consisting essentially of carbon is from 1 to 10 nm thick.
41. The transparent article according to claim 1 , wherein the scratch propagation blocker layer comprises a material selected from the group consisting of oxides of Zr; nitrides of Zr; oxynitrides of Zr; and mixtures thereof.
42. The transparent article according to claim 15 , wherein the scratch propagation blocker layer comprises a material selected from the group consisting of oxides of Zr; nitrides of Zr; oxynitrides of Zr; and mixtures thereof.
43. The transparent article according to claim 28 , wherein the scratch propagation blocker layer comprises a material selected from the group consisting of oxides of Zr; nitrides of Zr; oxynitrides of Zr; and mixtures thereof.
44. The transparent article according to claim 1 , wherein the scratch propagation blocker layer comprises a material selected from the group consisting of oxides of Hf; nitrides of Hf; oxynitrides of Hf; and mixtures thereof.
45. The transparent article according to claim 15 , wherein the scratch propagation blocker layer comprises a material selected from the group consisting of oxides of Hf; nitrides of Hf; oxynitrides of Hf; and mixtures thereof.
46. The transparent article according to claim 28 , wherein the scratch propagation blocker layer comprises a material selected from the group consisting of oxides of Hf; nitrides of Hf; oxynitrides of Hf; and mixtures thereof.
47. The transparent article according to claim 1 , wherein the scratch propagation blocker layer comprises a material selected from the group consisting of oxides of Ti, Zr, Hf, Cr, and Ta; nitrides of Zr; and oxynitrides of Zr.
48. The transparent article according to claim 15 , wherein the scratch propagation blocker layer comprises a material selected from the group consisting of oxides of Ti, Zr, Hf, Cr, and Ta; nitrides of Zr; and oxynitrides of Zr.
49. The transparent article according to claim 28 , wherein the scratch propagation blocker layer comprises a material selected from the group consisting of oxides of Ti, Zr, Hf, Cr, and Ta; nitrides of Zr; and oxynitrides of Zr.