LOW-EMISSIVE MATERIAL COMPRISING AN INTERMEDIATE COATING COMPRISING TWO DIFFERENT LAYERS CONTAINING SILICON

Abstract

A material includes a transparent substrate coated with a stack including at least one silver-based functional metal layer and at least two dielectric coatings, each dielectric coating including at least one dielectric layer, so that each functional metal layer is placed between two dielectric coatings, wherein the dielectric coating located in contact with the substrate includes an intermediate coating including two different layers containing silicon, the two layers containing silicon consist of different chemical elements or composed of the same elements in different proportions.

Claims

1. A material comprising a transparent substrate coated with a stack comprising at least one functional metal layer comprising silver and at least two dielectric coatings, each dielectric coating comprising at least one dielectric layer, so that each functional metal layer is placed between two dielectric coatings, wherein the dielectric coating located in contact with the substrate comprises an intermediate coating located directly in contact with the substrate and comprising two different layers comprising silicon, the two different layers comprising silicon are composed of different chemical elements or composed of the same elements in different proportions.

2. The material according to claim 1, wherein the intermediate coating has a thickness greater than or equal to 10 nm.

3. The material according to claim 1, wherein the intermediate coating has a thickness less than or equal to 50 nm.

4. The material according to claim 1, the wherein a thickness of the or each silver based functional metal layer is from 7 to 30 nm.

5. The material according to claim 1, wherein the two different layers comprising silicon are selected from layers based on oxide, based on nitride or based on silicon oxynitride.

6. The material according to claim 1, wherein the intermediate coating comprises at least one layer based on oxide or a layer based on silicon oxynitride.

7. The material according to claim 1, wherein the intermediate coating comprises a first layer comprising silicon based on silicon oxide, in contact with the substrate.

8. The material according to claim 7, wherein the intermediate coating comprises a second layer comprising silicon selected from layers based on silicon nitride and on silicon oxynitride.

9. The material according to claim 1, wherein the intermediate coating comprises a first layer comprising silicon based on silicon oxynitride, in contact with the substrate.

10. The material according to claim 9, wherein the intermediate coating comprises a second layer comprising silicon selected from layers based on silicon nitride and on silicon oxide.

11. The material according to claim 1, wherein the intermediate coating comprises a first layer comprising silicon based on silicon nitride, in contact with the substrate.

12. The material according to claim 11, wherein the intermediate coating comprises a second layer comprising silicon selected from layers based on silicon oxynitride and on silicon oxide.

13. The material according to claim 1, wherein the intermediate coating comprises at least one layer based on silicon nitride and a layer based on silicon oxynitride.

14. The material according to claim 1, wherein the dielectric coating located between the substrate and a first functional metal layer of the at least one functional metal layer and/or one or each dielectric coating located above the first functional metal layer located comprises a layer based on zinc oxide comprising at least 80% by weight of zinc relative to the weight of all the elements other than oxygen.

15. The material according to claim 1, wherein the dielectric coating located between the substrate and a first functional metal layer of the at least one functional metal layer and/or one or each dielectric coating located above the first functional metal layer located comprises a layer based on zinc tin oxide comprising at least 20% by weight of tin relative to the total weight of zinc and tin.

16. The material according to claim 1, wherein the stack comprises at least one dielectric layer based on zinc oxide and a layer based on zinc tin oxide.

17. The material according to claim 1, wherein each dielectric coating comprises at least one dielectric layer based on zinc oxide and a layer based on zinc tin oxide.

18. The material according to claim 1, wherein a sum of thicknesses of all the oxide-based layers present in the dielectric coating located between the substrate and a first functional metal layer of the at least one functional metal layer is greater than 50% of a total thickness of the dielectric coating.

19. The material according to claim 1, wherein a sum of thicknesses of all the oxide-based layers present in each dielectric coating located above a first functional metal layer of the at least one functional metal layer is greater than 50% of the total thickness of the dielectric coating.

20. A glazing comprising a material according to claim 1 and one, two three additional substrates.

21. A heating or cooling device comprising a heater or cooler and a chamber delimited by one or more walls, wherein at least one wall of the one or more walls comprises at least one glazing comprising a material according to claim 1.

Description

EXAMPLES

[0234] Stacks of thin layers defined below are deposited on substrates made of clear soda-lime glass with a thickness of 4 mm.

[0235] For these examples, the conditions of deposition of the layers deposited by sputtering (“magnetron cathode” sputtering) are summarized in table 1 below.

TABLE-US-00001 TABLE 1 Pressure Table Targets employed μbar Gas Index Si3N4 Si:Al 92/8% by wt 2 Ar 34%—N.sub.2 66% 2.05 SiON Si:Al 92/8% by wt 2 Ar 15%—O.sub.2 9%—N.sub.2 76% 1.7  SiO2 Si:Al 92/8% by wt 2 Ar 55%—O2 45% 1.50 SnZnO Sn:Zn 60/40% by wt 2 Ar 25%—O.sub.2 75% 2.05 ZnO Zn:Al(92/8%)Ox 2 Ar at 100% 2.0  NiCr Ni:Cr (80:20% at.) 2 Ar at 100% — Ag Ag 4 Ar at 100% — TiOx TiOx 2 Ar at 100% 2.35 at.: atomic; wt: weight; *: at 550 nm.

[0236] The materials and the physical thicknesses in nanometers (unless otherwise indicated) of each layer or coating of which the stacks are composed are listed in table 2 below as a function of their positions with regard to the substrate carrying the stack.

TABLE-US-00002 TABLE 2 Glazing Cp-1 Cp-2. Inv. DC TiOx 3 3 3 SnZnO 41 41 41 ZnO 7 7 7 BL NiCr 0.4 0.4 0.4 FL Ag 12.5 12.5 12.5 NiCr 0.1 0.1 0.1 DC ZnO 7 7 7 SnZnO 30 30 30 Int. C 0 5 10 Sub. Glass — — — DC: Dielectric coating; BL: Blocking layer; FL: Functional layer; Int. C: Intermediate coating.

[0237] A heat treatment is carried out on the coated substrates at 650° C. for 10 minutes.

[0238] Table 3 below lists the nature of the layers and the thicknesses of the intermediate coatings tested.

TABLE-US-00003 TABLE 3 Intermediate coating Cp-1 Cp-2 Inv. 1 Inv. 2 Inv. 3 Inv. 4 2nd layer SiON — — — 5 nm 5 nm — Si.sub.3N.sub.4 — — 5 nm — — 5 nm 1st layer SiON — — — — — 5 nm Si.sub.3N.sub.4 — — — — 5 nm — SiO.sub.2 — 5 nm 5 nm 5 nm — —

[0239] The first layer corresponds to the layer in contact with the substrate and the second layer is deposited on this first layer.

[0240] Evaluation of Haze and Chemical Durability.

[0241] The level of haze is evaluated as follows. After heat treatment, the glass is placed on a desk inclined by 20 degrees relative to the vertical, in a room with black walls. It is illuminated by a powerful lamp placed vertically on the desk. The observer places themselves in front of the desk, 1 m away. In this configuration, a hazy sample exhibits a marked milky appearance: it scatters light from the lamp far from its zone of specular reflection on the glass. On the contrary, a sample not exhibiting haze does not scatter any light toward the observer: it therefore appears dark. The following assessment indicators were used: [0242] “−”: The material is very hazy, [0243] “0”: The material is hazy, [0244] “+”: The material is not hazy.

[0245] The chemical durability is evaluated by a high-humidity (HH) test before and after heat treatment (HH-HT). The humidity (HH) test consists in storing samples at 90% relative humidity and at 60° C. for 56 days and in observing the possible presence of defects, such as corrosion pits. The following assessment indicators were used: [0246] ok: no pits, the material does not have any defects after 56 days of testing, [0247] nok: numerous pits, the material has defects and therefore does not pass the test.

[0248] The results are compiled in table 4 below.

TABLE-US-00004 TABLE 4 Test Cp-1 Cp-2 Inv-1 Inv-2 Inv-3 Inv-4 Haze − − + + + + HH ok ok ok ok ok ok HH-HT ok ok ok ok ok ok

[0249] Study of the Degradation of the Emissivity as a Function of the Duration of the Heat Treatment

[0250] The applicant has discovered that the advantageous properties of the invention, from the perspective of resistance to heat treatments, can be attributed to delayed degradation. This delay is observed when the intermediate coating based on layers comprising silicon is used.

[0251] This delay is illustrated by comparative curves depicting the degradation of the emissivity in percentage points as a function of the duration of the heat treatment in seconds. The heat treatment is carried out at a temperature of 705° C. The material Cp-1 is compared, respectively, with the material Cp-2 and with the materials of the invention. In order to evaluate the delay in degradation, the duration of the heat treatment in seconds, for which 2 degradation points of emissivity is obtained, is compared between the material Cp-1, and, respectively, the material Cp-2 and the materials of the invention.

[0252] No significant delay in the degradation is observed for the material Cp-2. In contrast, for each material according to the invention, a delay of much greater than 30 s is observed.

[0253] Indeed, by virtue of the intermediate coating of the invention, the time/temperature pair, during heating, becomes compatible with a transformation of the glass, such as tempering or bending, without haze or degradation of the emissivity. On the tempering and bending tools used, the glazing Cp-1 exhibited haze at time and temperature parameters which are very close to those required to obtain acceptable flatness, fragmentation and shape. The industrial tools used to bend and/or temper a layered glazing may have variability. A glazing must therefore be sufficiently robust to accommodate this process variability. The materials of the invention have this additional resistance. The 30 seconds delay observed are sufficient to ensure that the materials will not be degraded, regardless of the variability of the tempering process.

[0254] Finally, when a treatment of 15 minutes is carried out at 630° C., the materials Cp-1 and Cp-2 are degraded. In particular, a degradation in the emissivity of more than 4 percentage points (relative to a base value of 3%) is observed. In comparison, no degradation in the emissivity is observed for the materials of the invention during a heat treatment at this temperature, even when the duration of the heat treatment is much longer (22 minutes).