Transparent substrate provided with a thin-film stack

• US 6,355,334 B1
• Filed: 10/22/1999
• Issued: 03/12/2002
• Est. Priority Date: 10/22/1998
• Status: Expired due to Term

• Current Assignee: Saint-Gobain Vitrage
• Original Assignee: Saint-Gobain Vitrage
• Inventors: Didier, Fabrice, Rondeau, Véronique
• Primary Examiner(s): Jones, Deborah
• Assistant Examiner(s): BLACKWELL, GWENDOLYN
• Application Number:
  US09/422,941
• Time in Patent Office: 872 Days
• Field of Search: 428/212, 428/426, 428/428, 428/446, 428/688, 428/697, 428/698, 428/457, 359/350, 359/580, 359/585, 359/586
• US Class Current: 428/212
• 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 17/3644 the metal being silver
• CPC Class Codes: C03C 17/366 Low-emissivity or solar control coatings
• CPC Class Codes: C03C 2217/734 comprising an alternation of high and low refractive indexes
• CPC Class Codes: C03C 2217/78 Coatings specially designed to be durable, e.g. scratch-resistant
• CPC Class Codes: Y10T 428/24942 including components having same physical characteristic in differing degree

Abstract

The invention relates to a transparent substrate, in particular made of glass, provided with a thin-film stack including at least one metallic layer with infrared reflection properties, in particular a low-emission layer, arranged between two dielectric-based coatings.

According to the invention, the dielectric-based coating above the metallic layer has the following sequence of layers deposited in this order:

a) layer(s) with material(s) with refractive index n_i-2 of at most 2.2;

b) layer(s) with material(s) with refractive index n_i-1 at least 0.3 less than that of the last layer(s) n_i;

c) last layer(s) with material(s) with refractive index n_i substantially equal to n_i-2.

Claims

1. Transparent substrate, provided with a thin-film stack including at least one metallic layer with infrared reflection properties, arranged between two dielectric-based coatings, wherein the dielectric-based coating arranged above the metallic layer has the sequence of layers deposited in the following order:

a) one or more first layer(s) with materials(s) having a refractive index of at most 2.2;

b) one or more middle layer(s) with materials(s) having a refractive index of at least 0.3 less than one or more last layer(s) n_i; and

c) one or more last layer(s) with material(s) having a refractive index, substantially equal to the refractive index of the one or more first layers.

2. Substrate according to claim 1, wherein the metallic layer with infrared reflection properties is based on silver Ag.

3. Substrate according to claim 1 wherein the metallic layer with infrared reflection properties is directly in contact with the underlying dielectric-based coating.

4. Substrate according to claim 1, wherein the metallic layer with infrared reflection properties has a geometrical thickness of between 7 and 20 nanometers.

5. Substrate according to claim 1, wherein the substrate has a protective metallic layer placed immediately above and in contact with the layer with infrared reflection properties.

6. Substrate according to claim 5, wherein the said protective metallic layer is based on a single metal selected from niobium Nb, titanium Ti, chromium Cr or nickel Ni or an alloy of at least two of these metals.

7. Substrate according to claim 1, wherein the dielectric-based coating lying underneath the metallic layer with infrared reflection properties is a superposition of at least two layers, notably two metallic oxide layers or a nitride layer like AlN or Si3N4 and a metallic oxide layer like SnO2, ZnO, TiO2, with preferably a direct contact between the said coating and the said metallic layer with infrared reflection properties.

8. Substrate according to claim 7, wherein the dielectric based coating underneath the metallic layer with infrared reflection properties has a wetting layer based on zinc oxide ZnO, optionally doped with aluminum ZnO:

Al, in contact with the said layer with infrared reflection properties, and comprises preferably two layers including the said wetting layer.

9. Substrate according to claim 8, wherein the wetting layer has a geometrical thickness of between 5 and 40 nanometers.

10. Substrate according to one of claims 8 and 9, wherein the wetting layer is based on at least partly crystalized zinc oxide.

11. Substrate according to claim 1, wherein the last layer in the stack is a layer selected from one of the following materials:

silicon nitride Si₃N₄, optionally doped with aluminum Si₃N₄;

Al, aluminum nitride AlN, tin oxide SnO₂, mixed oxide of tin and zinc SnZnO_x, and carbides such as SiC, TiC, CrC, TaC.

12. Substrate according to claim 1, wherein the last layer in the stack has a geometrical thickness of between 5 and 20 nanometers.

13. Substrate according to claim 1, wherein the layer placed immediately underneath and in contact with one of the last layers in the stack has a refractive index of less than 1.75.

14. Substrate according to claim 1, wherein the layer placed immediately underneath and in contact with one of the last layers is based on silicon oxide SiO₂ or aluminum oxide Al₂O₃ or a mixture of these two oxides Al₂O₃:

SiO₂.

15. Substrate according to claim 1, wherein the layer underlying the layer placed immediately underneath and in contact with one of the last layers in the stack has a refractive index close to that of the last layer in the stack, preferably of the order of 2.

16. Substrate according to claim 1, wherein the stack is as follows:

Glass/SnO₂ or Si₃N₄;

Al or AlN/ZnO or ZnO;

Al/Ag/Ti or NiCr/ZnO or SnO₂/SiO₂ or Al₂O₃ or SiO₂;

Al₂O₃/SnO₂ or ZnO or SnZnO_x or AlN or Si₃N₄;

Al or (AlN/Si₃N₄;

Al) or (Si₃N₄;

Al/AlN) or (SnO₂/SnZnO_x).

17. Substrate according to claim 1, wherein the substrate has an emissivity ∈

of at most 0.05.

18. Low-emission or solar-protection multiple glazing, in particular double glazing, having the substrate according to claim 1, wherein the thin-film stack being at faces 2 and/or 3, and where appropriate, at face 5.

19. Low-emissivity double glazing having at least one substrate according to claim 1, wherein the substrate has an optical transmission T_L of at least 72%.

20. Double glazing according to claim 19, having two panes of glass, wherein the double glazing has a coefficient K less than or equal to 1.4 W/K.m² when the two panes of glass are separated by air, or less than or equal to 1.1 W/K.m² when the two panes of glass are separated by argon.

21. Substrate according to claim 1, wherein the substrate is made of glass.

22. Substrate according to claim 4, wherein the metallic layer with infrared reflection properties has a geometric thickness between 9 and 15 nanometers, so as to give it low-emissivity properties, or between 20 and 25 nanometers so as to give it solar-protection properties.

23. Substrate according to claim 6, wherein the protective metallic layer is an alloy of niobium and chromium (Nb/Cr) or of nickel and chromium (Ni/Cr), and wherein the protective metallic layer has a geometrical thickness of less than or equal to 2 nanometers.

24. Substrate according to claim 9, wherein the wetting layer has a geometrical thickness of between 15 and 30 nanometers.