GLASS COMPRISING A FUNCTIONAL COATING CONTAINING SILVER AND INDIUM

Abstract

A material includes a transparent substrate coated with a stack of thin layers including at least one silver-based functional metal coating, at least two dielectric coatings including at least one dielectric layer, so that each functional metal coating is positioned between two dielectric coatings, wherein the functional metal coating includes at least 1% by weight of indium relative to the weight of silver and indium in the functional metal coating.

Claims

1. A material comprising a transparent substrate coated with a stack of thin layers comprising at least one silver-based functional metal coating, at least two dielectric coatings comprising at least one dielectric layer, so that each functional metal coating is positioned between two dielectric coatings, wherein the functional metal coating comprises at least 1.0% by weight of indium relative to the weight of silver and indium in the functional metal coating.

2. The material as claimed in claim 1, wherein the functional coating comprises a metal layer based on an alloy of silver and indium.

3. The material as claimed in claim 1, wherein the functional coating comprises at least one indium-based metal layer and at least one silver-based metal layer.

4. The material as claimed in claim 1, wherein the functional coating comprises at most 5.0% by weight of indium relative to the weight of silver and indium in the functional metal coating.

5. The material as claimed in claim 1, wherein the functional coating comprises 1.0% to 3.0% by weight of indium relative to the weight of silver and indium in the functional metal coating.

6. The material as claimed in claim 1, wherein the functional metal coating comprises 0.05% to 1.0% by weight of tin relative to the weight of silver, indium and tin in the functional metal coating.

7. The material as claimed in claim 1, wherein the silver-based functional metal coating has a thickness of between 5 and 20 nm.

8. The material as claimed in claim 1, wherein the functional coating comprises at least one indium-based metal layer and at least two silver-based metal layers, so that each indium-based metal layer is positioned between two silver-based metal layers.

9. The material as claimed in claim 1, wherein the stack of thin layers additionally comprises at least one blocking layer located in contact with and above and/or below the functional metal coating selected from metal layers, metal oxide layers and metal oxynitride layers of one or more elements selected from titanium, nickel, chromium, tantalum and niobium.

10. The material as claimed in claim 1, wherein the stack of thin layers comprises a single functional coating.

11. The material as claimed in claim 1, wherein the stack of thin layers comprises at least one dielectric coating comprising at least one dielectric layer consisting of a nitride or an oxynitride of aluminum and/or of silicon.

12. The material as claimed in claim 1, wherein the dielectric coating located below the functional coating comprises a single layer consisting of a nitride or an oxynitride of aluminum and/or of silicon, having a thickness between 30 and 70 nm.

13. The material as claimed in claim 1, wherein the dielectric coating located above the functional coating comprises at least one layer consisting of a nitride or an oxynitride of aluminum and/or of silicon, having a thickness between 30 and 70 nm.

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

15. A process for preparing a material comprising a transparent substrate coated with a stack of thin layers deposited by cathode sputtering, optionally magnetic-field-assisted cathode sputtering, the process comprising the sequence of steps below: depositing at least one dielectric coating comprising at least one dielectric layer on the transparent substrate, then depositing a silver-based functional metal coating above the dielectric coating comprising 1% to 5% by weight of indium relative to the weight of silver and indium in the functional metal coating, then depositing a dielectric coating comprising at least one dielectric layer above the silver-based functional metal coating, subjecting the substrate thus coated to a heat treatment.

16. The material as claimed in claim 9, wherein the at least one blocking layer is selected from the group consisting of Ti, TiN, TiOx, Nb, NbN, Ni, NiN, Cr, CrN, NiCr, and NiCrN.

17. The material as claimed in claim 14, wherein the transparent substrate is: made of soda-lime-silica glass or made of polyethylene, polyethylene terephthalate or polyethylene naphthalate.

Description

EXAMPLES

[0151] Stacks of thin layers defined below are deposited on substrates made of soda-lime clear glass with a thickness of 3.9 mm.

[0152] The stacks are deposited, in a known manner, on a (magnetron process) cathode sputtering line in which the substrate travels under various targets.

[0153] For these examples, the conditions for deposition of the layers deposited by sputtering (magnetron cathode sputtering) are summarized in table 1.

TABLE-US-00001 TABLE 1 Deposition Targets used pressure Gas Index* Si.sub.3N.sub.4 Si:Al (92:8% by wt) 2-15 10.sup.3 mbar Ar:30-60%N.sub.2:40-70% 2.00 NiCr Ni:Cr (80:20 at. %) 1-5 10.sup.3 mbar Ar at 100% Ag Ag 2-3 10.sup.3 mbar Ar at 100% InSn In:Sn (90:10% by wt) 1-3 10.sup.3 mbar Ar at 100% at.: atomic; wt: weight; *at 550 nm.

[0154] Table 2 lists the materials and the physical thicknesses in nanometers (unless otherwise indicated) of each layer or coating which forms the stacks as a function of their position with regard to the substrate bearing the stack (final line at the bottom of the table). The thicknesses given in this table correspond to the thicknesses before tempering.

TABLE-US-00002 TABLE 2 Materials Comparative Invention DC Si.sub.3N.sub.4 (35 nm) Si.sub.3N.sub.4 (35 nm) Blocking layer NiCr (0.17 nm) NiCr (0.17 nm) Functional coating Ag (10 nm) AgIn sequence (cf. Tab. 3) Blocking layer NiCr (0.35 nm) NiCr (0.35* or 0.17** nm) DC Si.sub.3N.sub.4 (35 nm) Si.sub.3N.sub.4 (35 nm) Sub. Glass Glass DC = Dielectric coating; *Ex. 1-Ex. 10; **Ex. 11-Ex. 13

[0155] The functional coatings of the materials according to the invention comprise at least one silver layer and one indium layer. Each silver layer and each indium layer of one and the same functional coating are respectively chosen to have the same thickness.

[0156] Table 3 defines, for each material: [0157] the sequence of thin layers forming the functional coating, [0158] the individual thicknesses (Indiv. th.) of each silver and indium layer, [0159] the total thickness of the silver and indium layers of a functional coating.

[0160] The densities of the indium and of the tin are 7.31 and the density of the silver is 10.5.

[0161] The indium and tin layers comprise 90% by weight of indium and 10% by weight of tin. In order to be free of proportions of tin, an estimated indium thickness (Est. In th.) corresponding to the thickness of the indium layer if it did not comprise tin was calculated (Indiv. th. In 90/100).

[0162] In order to evaluate the relative proportions of silver and indium, the weights of silver and indium per cm.sup.2 in the functional coating were determined. The weight of indium relative to the weight of indium and silver in the functional coating corresponds to: % In=[(weight of In/cm.sup.2)/(weight of In/cm.sup.2+weight of Ag/cm.sup.2)100].

[0163] The following abbreviations are used in table 3: [0164] Indiv. th.: Thickness of a silver layer or of an indium layer forming the functional coating, in nm; [0165] Total th.: Total thickness of the silver layers and of the indium and tin layers forming the functional coating; [0166] Est. In th.: Estimated indium thickness; [0167] % In: proportions by weight of indium relative to the weight of silver and indium in the functional metal coating.

TABLE-US-00003 Indiv. th. Total th. Est. Weight Tab. 3 Sequence Ag InSn Ag InSn In th. Ag/cm.sup.2 In/cm.sup.2 % In Inv. 1 Ag/(In/Ag)6 1.23 0.14 8.6 0.84 0.76 90.2 5.5 5.8 Inv. 2 Ag/(In/Ag)4 1.72 0.11 8.6 0.44 0.40 90.2 2.9 3.1 Inv. 3 Ag/(In/Ag)4 1.72 0.16 8.6 0.64 0.58 90.2 4.2 4.5 Inv. 4 Ag/In/Ag 4.3 0.3 8.6 0.6 0.54 90.2 3.9 4.2 Inv. 5 Ag/In/Ag 4.3 1.0 8.6 2 1.80 90.2 13.2 12.7 Inv. 6 Ag/In/Ag 4.3 2.0 8.6 4 3.60 90.2 26.3 22.6 Inv. 7 In/(Ag/In)2 4.3 0.67 8.6 2 1.80 90.2 13.2 12.7 Inv. 8 Ag/(In/Ag)4 1.72 0.11 8.6 0.44 0.40 90.2 2.9 3.1 Inv. 9 In/Ag/In 8.6 0.3 8.6 0.6 0.54 90.2 3.9 4.2 Inv. 10 Ag/(In/Ag)4 2.4 0.11 12 0.44 0.40 125.9 2.9 2.2 Inv. 11 Ag/(In/Ag)4 2.8 0.13 14 0.5 0.45 146.9 3.3 2.2 Cmp. Ag 12 12 12 Cmp. Ag 14 14 13 Cmp. Ag 10 10 14

[0168] The substrates coated with the stacks undergo a thermal tempering type heat treatment for 10 minutes at a temperature of 640 C. (HT).

[0169] In order to evaluate the chemical resistance of the stack, an accelerated aging test, referred to as a test of resistance to high humidity, was carried out. This test consists in placing a material in an oven heated at 120 C. for 480 minutes having a relative humidity of 100% (RH). The visual observation of the material according to the invention after heat treatment makes it possible to note the absence of haze.

[0170] The sheet resistivity (Rsq), measured in ohms with a Nagy device, corresponds to the resistance of a sample having a width equal to the length (for example 1 meter) and having any thickness. The sheet resistivity is measured: [0171] before and after heat treatment, [0172] before and after accelerated aging on materials that have undergone a high-temperature heat treatment.

[0173] In order to evaluate the hold of the stack on the substrate, an adhesion test corresponding to the cross-cut test according to the standard EN ISO 2409 was carried out (tape test or T. ad.). This test consists in producing a lattice pattern with the cutter and then in applying a piece of standardized adhesive that is removed after a certain period of time. The inspection of the cross-cut surface after removal of the adhesive makes it possible, depending on the amount of thin layers pulled off, to characterize the hold of the stack. According to the invention, the test is described as: [0174] OK when no removal of thin layers is observed, [0175] NOK when removal of thin layers is observed.

[0176] Finally, certain optical characteristics, when the materials are assembled as single glazing, the stack being positioned on face 2, face 1 of the glazing being the outermost face of the glazing, were measured, including: [0177] R.sub.L indicates: the light reflection in the visible region in %, measured under the illuminant A with the 2 observer on the side of the interior face, face 2; [0178] a*R and b*R indicate the colors in reflection a* and b* in the L*a*b* system, measured under the illuminant D65 with the 10 observer on the side of the outermost face and measured thus perpendicularly to the glazing; [0179] T.sub.L indicates the light transmission in the visible region in %, measured under the illuminant A with the 2 observer; [0180] a*t and b*t indicate the colors in transmission a* and b* in the L*a*b* system, measured under the illuminant A with the 2 observer on the side of the outermost face and measured thus perpendicularly to the glazing; [0181] Abs. indicates the light absorption in the visible region in %, measured under the D65 illuminant with the 10 observer.

[0182] The following abbreviations are used in tables 4 and 5: [0183] HT: Heat treatment, [0184] Rht: Variation in sheet resistivity between after and before heat treatment, [0185] Rhr: Variation in sheet resistivity between after heat treatment and after heat treatment and high-humidity test, [0186] R.: Sheet resistivity.

TABLE-US-00004 % Reflection Transmission T. Tab.4 In. HT R.sub.L a*R b*R T.sub.L a*t b*t Abs R. ad. Rht R. Inv. 1 5.8 Before 11.3 1.9 7.6 62.2 2.4 3.1 26 28.3 OK 4.5 After 11.3 4.7 7.5 62.7 3.4 5.8 26 23.5 OK Inv. 2 3.1 Before 10.2 0.7 5.8 65.8 1.8 2.3 24 23 OK 4.7 After 9.7 5.5 6.2 68.6 3.7 4.5 22 18.3 OK <20 Inv. 3 4.5 Before 10 1.5 4.2 66.4 1.9 1.8 24 26.3 OK 4.1 After 10.8 5.5 8.8 65.8 3.2 5.3 23 22.2 OK Inv. 4 4.2 Before 9.4 0.7 4.8 68.5 1.5 1.8 22 19 OK +6.2 <20 After 9.8 3.3 6.5 65.8 2.7 4.7 24 25.2 OK Inv. 5 12.7 Before 10.7 2.2 8.6 62 2 2.7 27 23 OK 1.1 After 11.5 6.7 11.3 61.6 3.9 4.7 27 21.9 OK Inv. 6 22.6 Before 13.8 2.3 12.6 51.7 2.1 3.5 34 30.7 OK +1.8 After 14.9 5 12.4 50.4 3.4 3.8 35 32.5 NOK Inv. 7 12.7 Before 11.8 2.4 9.8 58.9 2.3 3.4 29 26.4 OK +3.7 After 12.2 6.3 10.9 59.5 3.9 5.2 28 29.7 OK Inv. 8 3.1 Before 9.8 1.1 5.2 67.3 1.7 2.2 23 22.4 OK 5.2 After 9.7 5.6 8.4 67.6 3.3 5.3 23 17.2 OK <20 Inv. 9 4.2 Before 9.6 1.1 4.1 68.6 4.6 1.6 22 17.8 OK <20 After 12 0.8 7.8 59.9 2.1 4.7 28 NOK Inv. 10 2.2 Before 9 6 11.6 69 2.5 2.4 22 9.6 OK 3.1 <10 After 12.9 9.6 17.8 68.2 4.1 5.9 19 6.5 OK <10 Inv. 11 2.2 Before 12.3 8.7 19.9 60 3.4 4.2 28 8.5 1.5 <10 After 18.8 8.6 23.6 55.9 4.2 10.4 25 7.0 <10 Cmp. Before 10 6 12.9 65.1 2.3 2.9 25 7.6 <10 12 Cmp. Before 12.1 9 19.2 62.4 3.2 4 25 5.9 +0.3 <10 13 After 18.6 8.9 23.7 58 4.2 10.7 23 6.2 <10 Cmp. After 7.1 71.0 3.6 4.7 11.3 <20 14 Reflection Transmission Tab. 5 HT/TR R.sub.L a*R b*R T.sub.L % a*t b*t Abs R Rrh R Inv. 10 After HT 12.9 9.6 17.8 68.2 4.1 5.9 18.9 6.5 <10 After RH 12.2 9.9 17.4 69.1 4.1 5.4 18.7 6.4 0.1 <10 After RH 7.9 +1.4 <10 Cmp. 14 After HT 7.1 71.0 3.6 4.7 7.9 <10 After RH 11.3 +3.4 <20

Resistance to the Heat Treatment:

[0187] These examples show that in the majority of cases, the addition of indium to the silver in the functional coating does not impair the hold of the stack on the substrate insofar as the adhesion tests are satisfied.

[0188] When the functional coating comprises a sequence of several silver and indium layers, better results are obtained when this sequence of layers begins and/or finishes with a silver layer.

[0189] Better results are also obtained when the functional coating comprises less than 5% by weight of indium. Examples Inv.5. Inv.6 and Inv.7 have high sheet resistivity values.

[0190] When the functional coatings comprise at least 3% by weight of indium, a gain in resistivity is observed following the heat treatment that is expressed by values of Rht that are negative and less than 2. This tendency is not systematically observed when the functional coatings comprise less than 3% by weight of indium since the sheet resistivity values are then very low and in particular less than 10 ohm per square.

[0191] When the functional coatings comprise proportions of less than 4% and better still of 1 to 3% by weight of indium relative to the weight of indium and silver, the sheet resistivity is not increased significantly due to the addition of indium compared to a similar stack based on a functional coating solely based on silver. In particular, for examples Inv.10 and Inv.11 comprising less than 2.5% by weight of indium relative to the weight of indium and silver, sheet resistivities of less than 10 ohm before heat treatment are observed.

[0192] But above all, the sheet resistivity after heat treatment is not increased significantly, or is even lowered. For this, the examples according to the invention Inv.10 and Inv.11 before and after heat treatment can be compared with the comparative examples Cmp.12 and Cmp 13.

[0193] Since the resistivity is in general proportional to the emissivity, this means that the excellent thermal performances are not modified due to the addition of indium.

Resistance to Wet Corrosion

[0194] The comparative example (Cmp.14), that does not comprise indium in the functional coating, has, after aging, a much higher sheet resistivity than that of the example according to the invention Inv.10 (11.3 ohm for Cmp.14 and 6.4 or 7.9 ohm for Inv.10). The comparative material is therefore less effective than the material of the invention after aging.

[0195] Furthermore, this significant increase in the sheet resistivity following the accelerated aging is accompanied by corrosion that is plainly visible.

In Conclusion

[0196] The material according to the invention, following a high-temperature heat treatment and following an aging test is not hazy. No increase in the sheet resistivity is observed either. These two observations make it possible to conclude that the solution of the invention makes it possible to considerably improve the chemical resistance of the stack.

[0197] The functional coating according to the invention makes it possible to maintain high light transmission values after a heat treatment, and this despite the not insignificant proportions of indium used.

[0198] The solution of the invention therefore makes it possible to obtain a stability of the characteristics of the glazing before and after the heat treatment.

[0199] The excellent chemical stability of the stack according to the invention enables the use of the material with the stack positioned either on an outer face, that is to say in contact with the ambient air, or inner face of a substrate.