GLAZING COMPRISING A PROTECTIVE UPPER LAYER MADE FROM HYDROGENATED CARBON

Abstract

A material including a transparent substrate coated with a stack acting on infrared radiation includes at least one functional layer and at least one upper protective layer deposited above at least a part of the functional layer. The upper protective layer is a hydrogenated carbon layer, within which layer the carbon atoms form carbon-carbon and carbon-hydrogen bonds and are essentially in an sp.sup.2 hybridization state.

Claims

1. A material comprising a transparent substrate coated with a stack acting on infrared radiation comprising: at least one functional layer and at least one upper protective layer deposited above at least a part of the functional layer, wherein the upper protective layer is a hydrogenated carbon layer, within which layer the carbon atoms form carbon-carbon and carbon-hydrogen bonds and are essentially in an sp.sup.2 hybridization state and which comprises at least 10% of hydrogen atoms with respect to the total number of carbon and hydrogen atoms.

2. The material as claimed in claim 1, wherein the material is configured to undergo a heat treatment.

3. The material as claimed in claim 1, wherein the material is untempered.

4. The material as claimed in claim 1, wherein the material is tempered.

5. The material as claimed in claim 1, wherein the material is tempered and/or bent.

6. The material as claimed in claim 1, wherein the upper protective layer has a thickness of greater than or equal to 5 nm.

7. The material as claimed in claim 1, wherein the upper protective layer has a thickness of greater than 10 nm.

8. The material as claimed in claim 1, wherein the hydrogenated carbon layer comprises at least 20% of hydrogen atoms, with respect to the total number of carbon and hydrogen atoms.

9. The material as claimed in claim 1, wherein the hydrogenated carbon layer comprises at least 25% of hydrogen atoms, with respect to the total number of carbon and hydrogen atoms.

10. The material as claimed in claim 1, wherein the hydrogenated carbon layer has a thickness of at least 1 nm and comprises at least 34% of hydrogen atoms with respect to the total number of carbon and hydrogen atoms.

11. The material as claimed in claim 1, wherein the hydrogenated carbon layer has a thickness of greater than or equal to 10 nm and comprises at least 27% of hydrogen atoms with respect to the total number of carbon and hydrogen atoms.

12. The material as claimed in claim 1, wherein the variation in the light absorption in the visible region brought about by the upper protective layer is less than 10%.

13. The material as claimed in claim 1, wherein the functional layer is chosen from: a functional metal layer based on silver or on a silver-containing metal alloy, a functional metal layer based on niobium, a functional layer based on niobium nitride.

14. The material as claimed in claim 1, wherein the stack comprises at least one functional layer and at least two coatings based on dielectric materials, each coating comprising at least one dielectric layer, so that each functional metal layer is positioned between two coatings based on dielectric materials.

15. The material as claimed in claim 1, wherein the stack comprises a dielectric layer based on silicon and/or aluminum nitride located above at least a part of the functional layer and below the upper protective layer.

16. The material as claimed in claim 1, wherein the substrate is: made of glass, or made of polymer.

17. A process for the preparation of a material comprising a transparent substrate coated with a stack acting on infrared radiation, comprising: depositing, by magnetic-field-assisted cathode sputtering, starting from the transparent substrate: at least one functional layer and at least one upper protective layer deposited above at least a part of the functional layer, wherein the upper protective layer is a hydrogenated carbon layer obtained by sputtering a carbon target in a reactive atmosphere comprising a hydrocarbon.

18. The process for the preparation of a material as claimed in claim 17, wherein the reactive atmosphere comprises a hydrocarbon chosen from methane and acetylene.

19. The process for the preparation of a material as claimed in claim 17, wherein the reactive atmosphere comprises argon.

20. The process for the preparation of a material as claimed in claim 18, wherein the atmosphere comprises at least 5% by volume of methane with respect to the volume of argon.

21. The process for the preparation of a material as claimed in claim 18 wherein the atmosphere comprises at least 10% by volume of methane with respect to the volume of argon.

22. A method of using the material as claimed in claim 1, comprising: manufacturing a glazing.

Description

EXAMPLES

[0094] Stacks of thin layers defined below are deposited on substrates made of clear soda-lime glass with a thickness of 4 mm.

[0095] For these examples, the conditions for deposition of the layers deposited by sputtering (“magnetron cathode” sputtering) are summarized in table 1 below.

TABLE-US-00001 TABLE 1 Targets Deposition employed pressure Gases Index* Si.sub.3N.sub.4 Si:Al (92:8% 8*10.sup.−3 mbar Ar 47%—N.sub.2 2.00 by weight) 53% AZO Zn:Al (2% 1.5*10.sup.−3 mbar Ar 91%—O.sub.2 1.90 by weight) 9% Ag Ag 8*10.sup.−3 mbar Ar at 100% — NiCr Ni:Cr (80:20% 2*10.sup.−3 mbar Ar at 100% — at.) TiO.sub.2 TiO.sub.x 1.5*10.sup.−3 mbar Ar 88%—O.sub.2 2.32 12% C Graphite 1.5*10.sup.−3 mbar Ar at 100% 2.25 C:H 5% Graphite 1.5*10.sup.−3 mbar Ar 95%—CH.sub.4 1.70 5% C:H 10% Graphite 1.5*10.sup.−3 mbar Ar 90%—CH.sub.4 1.70 10% at.: by atoms; *at 550 nm

[0096] The nonhydrogenated carbon layers, denoted “C”, are obtained without injection of methane into the argon atmosphere during the deposition of said layer.

[0097] The hydrogenated carbon layers, denoted “C:H X%”, are obtained with injection of methane into the argon atmosphere during the deposition of said layer. X represents the percentage by volume of methane added to the argon. The percentages studied are 5% and 10% by volume, with respect to the volume of argon.

I. Determination of the Amounts of Hydrogen in the Protective Layers

[0098] The hydrogen content of hydrogenated carbon layers deposited on an Si.sub.3N.sub.4 underlayer was determined by the ERDA (Elastic Recoil Detection Analysis) technique. These analyses make it possible to determine the amount of hydrogen present in the layers. The concentrations correspond to the number of atoms per cm.sup.2 of surface area analyzed.

[0099] The value given for hydrogen, No. of H, measured by ERDA, corresponds for these tests to the total number of hydrogen atoms present in a volume consisting of one cm.sup.2 of a protective layer with a thickness of approximately 100 nm.

[0100] The value given for the concentration of (C+H), No. of (C+H), corresponds to the total number of hydrogen and carbon atoms present in a volume consisting of one cm.sup.2 of a protective layer with a thickness of approximately 100 nm. This value is estimated from the theoretical density of carbon of 2.25 g/cm.sup.3 and by quantification of the ERDA spectra by virtue of simulations.

[0101] Finally, in order to be freed from the thickness of the protective layer deposited, the ratio of the total number of hydrogen atoms per cm.sup.2 of surface area analyzed, measured by ERDA, to the thickness of the layer is calculated and corresponds to the H/Thickness ratio with the thickness chosen in nm.

TABLE-US-00002 Concentration Thickness No. of H/Thickness Protective layer (nm) No. of H* (C + H) H/(C + H) ratio C = nonhydrogenated 100  90 ± 5 × 10.sup.15 1000 × 10.sup.15  9% 0.9 × 10.sup.15 C:H 5% = 5% hydrogenated 110 297 ± 15 × 10.sup.15 1100 × 10.sup.15 27% 2.7 × 10.sup.15 C:H 10% = 10% 125 425 ± 20 × 10.sup.15 1250 × 10.sup.15 34% 3.4 × 10.sup.15 hydrogenated

II. Optical and Mechanical Properties

[0102] The materials and the physical thicknesses in nanometers (unless otherwise indicated) of each layer of which the stack devoid of protective layer is composed are listed in the table below as a function of their positions with regard to the substrate carrying the stack.

TABLE-US-00003 Stack devoid of protective layer Thickness Coating based on dielectric materials Si.sub.3N.sub.4 30 AZO 5 Blocking layer BO NiCr 0.5 Functional layer Ag 10 Coating based on dielectric materials AZO 5 Si.sub.3N.sub.4 30 Substrate (mm) glass 4

[0103] The materials comprising the protective layers defined above were tested.

TABLE-US-00004 In. Material Cp. 1 Cp. 2 Cp. 3 In. 1 In. 2 In. 3 In. 4 In. 5 6 Protective layers C 1 1 10 — — — — — — C:H 5% — — — 1 — 1 — 10 — C:H 10% — — — — 1 — 1 — 10 TiO.sub.x 2 — — 2 2 — — — — Stack devoid of protective layer Substrate

[0104] For each of these materials, light absorption in the visible region was measured according to the D65 illuminant at 10° Observer. Finally, all were subjected to the Erichsen scratch test (EST), which consists in applying a force to the sample, in newtons, using a tip (Van Laar tip, steel ball). Depending on the scratch resistance of the stack, different types of scratches can be obtained: continuous, noncontinuous, wide, narrow, and the like.

[0105] The EST score ranges from 0 to 1: 0 being the best and 1 the worst. This score was calculated from the EST scratch width at 0.7 N, measured in 3 distinct points using an optical microscope. The formula for calculating this score S is as follows:

[00001]$S=\frac{W-W_{\min }}{W_{\max }-W_{\min }}$

W is the mean scratch width of the sample considered, W.sub.min that of the sample giving the smallest scratch width and W.sub.max the greatest.

TABLE-US-00005 Material Cp. 1 Cp. 2 Cp. 3 In. 1 In. 2 In. 3 In. 4 In. 5 In. 6 Absorption (%) 7-8 7-8 22-23 7-8 7-8 7-8 7-8 7-8 7-8 Scratch width, 0.7 N 1.2 1 0.5 0.8 1.2 1.2 0.5 0.2 0.1 EST score 1.00 0.82 0.36 0.64 1.00 1.00 0.36 0.09 0.00

[0106] The absorption of the hydrogenated carbon layers is greatly reduced with respect to the absorption of nonhydrogenated carbon layers. The hydrogenated carbon layers according to the invention, whatever their thickness (In. 1 to In. 6), exhibit an absorption equal to that obtained with conventionally used protective layers based on carbon of 1 nm (Cp. 1, Cp. 2).

[0107] These hydrogenated carbon layers can thus be used as thick protective layers without modifying the optical properties of the material, such as the absorption, and produce a significant improvement in the scratch resistance.

[0108] When the protective layer is a thin carbon-based layer, a scratch resistance is obtained which is reflected by EST scores of greater than 0.5: nonhydrogenated carbon layer of 1 nm (Cp. 1, Cp. 2), hydrogenated carbon layer of 1 nm (In. 1, In. 2, In. 3).

[0109] When the protective layer is a thick carbon layer, the scratch resistance is improved, which is reflected by lower EST scores and in particular scores lower than or of the order of 0.5 (Cp. 3, In. 5 and In. 6).

[0110] The use as a thick layer, in particular of the order of 10 nm, makes it possible to considerably improve the scratch resistance. It is found that, from the viewpoint of the scratch resistance, the results obtained for the materials of the invention comprising a 10 nm layer of hydrogenated carbon (In. 5=0.2; In. 6=0.1) are much better than those obtained for a thick nonhydrogenated carbon layer (Cp. 3=0.5). This shows that there exists a synergy related to the use of a thick carbon layer and of a hydrogenated carbon layer resulting in an excellent scratch resistance being obtained.

[0111] Finally, it is found that the hydrogenated carbon layers comprising high proportions of hydrogen exhibit a better scratch resistance whatever their thickness (In. 5 and In. 6).