LOW-EMISSIVITY MATERIAL COMPRISING A SILICON NITRIDE- OR OXYNITRIDE-BASED LAYER AND A ZINC TIN OXIDE-BASED LAYER

Abstract

A material includes a 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 between two dielectric coatings, wherein the dielectric coating located in contact with the substrate includes a layer including silicon selected from silicon oxynitride or nitride-based layers located in contact with the substrate; a layer based on zinc oxide and tin including at least 20% by mass of tin relative to the total mass of zinc and tin located in contact with the layer including silicon, the sum of thicknesses of all oxide-based layers present in the dielectric coating located between the substrate and the first functional metal layer and/or in each dielectric coating located above the first functional layer is greater than 50% of the total thickness of the dielectric coating.

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 arranged between two dielectric coatings, wherein the: dielectric coating located in contact with the transparent substrate comprises: a layer comprising silicon selected from silicon oxynitride or nitride-based layers located directly in contact with the transparent substrate, a layer based on zinc oxide and tin comprising at least 20% by mass of tin relative to the total mass of zinc and tin located directly in contact with the layer comprising silicon, a sum of thicknesses of all oxide-based layers present in the dielectric coating located between the transparent substrate and a first functional metal layer of the at least one functional metal layer and/or in each dielectric coating located above the first functional metal layer is greater than 50% of a total thickness of the dielectric coating.

2. The material according to claim 1, wherein the layer comprising silicon has a thickness of greater than or equal to 5 nm.

3. The material according to claim 1, wherein the layer comprising silicon has a thickness of between 8 and 25 nm.

4. The material according to claim 1, wherein the layer comprising silicon comprises at least 60% by mass of silicon relative to the mass of all elements other than nitrogen and oxygen.

5. The material according to claim 1, wherein the layer comprising silicon comprises a silicon oxynitride layer having a refractive index at 550 nm that is between 1.60 and 2.00.

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

7. The material according to claim 1, wherein each dielectric coating located above the first functional metal layer comprises a zinc-tin oxide-based layer comprising at least 20% tin by mass with respect to the total mass of zinc and tin.

8. The material according to claim 1, wherein the dielectric coating located between the transparent substrate and the first functional metal layer comprises at least one zinc-tin oxide-based layer and a zinc oxide-based dielectric layer.

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

10. The material according to claim 1, wherein the sum of the thicknesses of all oxide-based layers present in the dielectric coating located between the transparent substrate and the first functional metal layer is greater than 60% of the total thickness of the dielectric coating.

11. The material according to claim 1, wherein the sum of the thicknesses of all oxide-based layers present in the dielectric coating located between the transparent substrate and the first functional metal layer is greater than 70% of the total thickness of the dielectric coating.

12. The material according to claim 1, wherein the sum of the thicknesses of all oxide-based layers present in each dielectric coating located above the first functional metal layer is greater than 60% of the total thickness of the dielectric coating.

13. The material according to claim 1, wherein at least the transparent substrate coated with the stack is curved and/or tempered.

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

15. The glazing according to claim 14, comprising a functional coating other than the stack comprising the at least one functional metal layer, the functional coating being located: on the transparent substrate comprising the at least one functional metal layer, on a face opposite that comprising the at least one functional metal layer, or on a face of a substrate different from the transparent substrate comprising the at least one functional metal layer.

16. A heating or cooling device comprising a heater or cooler and an enclosure 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.

17. A cooling device according to claim 16, wherein the cooling device is of a freezer and the glazing consists of the material and the stack is located on a face of the transparent substrate in contact with the enclosure.

Description

EXAMPLES

[0235] Stacks of thin layers defined below are deposited on substrates made of clear soda-lime glass with a thickness of 4 mm.

[0236] For these examples, the conditions of the 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 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% — TiO.sub.x TiOx 2 Ar 88%-O.sub.2 12% 2.35 at.: atomic; wt: weight; *: at 550 nm.

[0237] 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 Inv. Inv. Inv. Inv. Inv. Inv. Glazing Cp-1 1-1 1-2 1-3 2-1 2-1 2-3 DC TiOx 3 3 3 3 3 3 3 SnZnO 41 41 41 41 41 41 41 ZnO 7 7 7 7 7 7 7 BL NiCr 0.4 0.4 0.4 0.4 0.4 0.4 0.4 FL Ag 12.5 12.5 12.5 12.5 12.5 12.5 12.5 BL NiCr 0.1 0.1 0.1 0.1 0.1 0.1 0.1 DC ZnO 7 7 7 7 7 7 7 SnZnO 30 26 21 17 25 20 21 SiON 0 5 10 15 — — SiN 0 — — — 5 10 15 Sub. Glass — — — — — — — DC: Dielectric coating; BL: Blocking layer; FL: Functional layer.

[0238] In order to preserve the optical properties of cp-1, the Inv-1 and Inv-2 stacks must be corrected. This involves reducing the thickness of SnZnO under the silver layer, in proportion to the thickness and optical index of the layer comprising silicon.

[0239] A heat treatment is performed on the coated substrates at 650° C. for 10 minutes.

[0240] Evaluation of Haze and Chemical Durability.

[0241] The level of haze was quantified in the following way: After thermal treatment, the tempered glass is placed on a desk tilted 20 degrees from the vertical, in a room with black walls. It is lit by a powerful lamp placed vertically on the desk. The observer stands in front of the desk, 1 m away. In this configuration, a hazy sample shows a marked milky appearance: It scatters the light from the lamp away from its specular reflection area on the glass. On the other hand, a sample without haze does not diffuse any light towards the observer, so it 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] Chemical durability is evaluated by a high humidity test before (HH) and after heat treatment (TT-HH). The humidity (HH) test consists in storing samples for 56 days at 90% relative humidity and at 60° C. and observing the possible presence of defects, such as corrosion pits. The following assessment indicators were used: [0246] ok: no pitting, the material has no defects after 56 days of testing, [0247] nok: much pitting, the material has defects and therefore does not pass the test.

[0248] The results are compiled in table 3 below.

TABLE-US-00003 TABLE 3 Test Cp-1 Inv-1-1 Inv-1-2 Inv-1-3 Inv-2 Inv-2-2 Inv-2-3 Haze − + + + + + + HH ok ok ok ok ok ok ok TT-HH ok ok ok ok ok ok ok

[0249] Study of Emissivity Degradation Based on Heat Treatment Duration

[0250] The applicant has found that the advantageous properties of the invention in terms of resistance to heat treatment are attributable to delayed degradation. This delay is observed when the stack comprises the layer sequence according to the invention in contact with the substrate.

[0251] This delay is illustrated by comparative curves representing the emissivity degradation in percentage points based on heat treatment duration in seconds. The heat treatment is performed at a temperature of 705° C. The material Cp-1 is compared to the materials of the invention. To evaluate the degradation, the duration of the heat treatment in seconds is compared, for which 2 points of emissivity degradation are obtained between the material Cp-1 and the materials of the invention respectively. For each material according to the invention, a delay of well over 30 s is observed.

[0252] Indeed, thanks to the use of the layer sequence according to the invention, the time/temperature pairing during heating becomes compatible with a transformation of the glass, such as tempering or bending, without haze or degrading emissivity. On the tempering and bending tools used, the glazing Cp-1 showed haze at time and temperature parameters very close to those needed to achieve flatness, fragmentation, and acceptable shape. The industrial tools used to bend and/or temper a coated glass may vary. A glazing must therefore be robust enough to accept these process variabilities. The materials of the invention have this additional strength. The observed 30-second delay is sufficient to ensure that the materials will not be degraded, regardless of the variability of the tempering process.

[0253] Finally, when a 15-minute treatment is performed at 630° C., the material Cp-1 is degraded. In particular, we observe a degradation of emissivity of more than 5 percentage points. By comparison, no degradation of emissivity is observed for the materials of the invention when heat-treated at this temperature, even when the duration of the heat treatment is much longer (22 minutes).

[0254] Table 5 below shows the impact of a heat treatment at 650° C. for 15 minutes on the emissivity. The emissivity before heat treatment for each material is approximately 3.7 to 4%.

TABLE-US-00004 TABLE 5 Emissivity Material (%) Cp. 1 8.9 Inv. 1-1 2.8 Inv. 1-2 2.8 Inv. 1-3 2.9 Inv. 2-1 3.1 Inv. 2-2 3.3 Inv. 2-3 2.9

[0255] Heavy degradation is observed for the material Cp-1 and a significant gain for each material of the invention.