LOW-E MATERIAL COMPRISING A THICK LAYER BASED ON SILICON OXIDE

Abstract

A material includes a transparent substrate coated with a stack including at least one functional metal layer based on silver and at least two dielectric coatings, each dielectric coating including at least one dielectric layer, in such a way that each functional metal layer is positioned between two dielectric coatings, wherein the stack includes a layer based on silicon oxide having a thickness of greater than or equal to 12 nm located directly in contact with the substrate.

Claims

1. A material comprising a transparent substrate coated with a stack comprising at least one functional metal layer based on silver and at least two dielectric coatings, each dielectric coating having at least one dielectric layer, so that each functional metal layer is positioned between two dielectric coatings, wherein the stack comprises a layer based on silicon oxide having a thickness of greater than or equal to 12 nm located directly in contact with the substrate.

2. The material according to claim 1, wherein the layer based on silicon oxide has a thickness of greater than or equal to 14 nm.

3. The material according to claim 1, wherein the layer based on silicon oxide has a thickness less than or equal to 60 nm.

4. 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 has a zinc oxide-based layer comprising at least 80% by mass of zinc relative to the mass of all elements other than oxygen.

5. 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 has a zinc-tin oxide-based layer comprising at least 20% by mass of tin relative to the total mass of zinc and tin.

6. The material according to claim 1, wherein the stack has at least one zinc oxide-based dielectric layer and a zinc-tin oxide-based layer.

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

8. The material according to claim 1, wherein a sum of the 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 and/or in one or each dielectric coating located above the first functional layer is greater than 50% of a total thickness of the dielectric coating.

9. 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 silver-based functional layer consists solely of oxide layer.

10. The material according to claim 1, wherein all the layers of the stack are deposited by magnetic-field-assisted cathode sputtering.

11. The material according to claim 1, wherein the stack comprises successively: a dielectric coating located below the functional metal layer and comprising the silicon oxide-based layer, a zinc-tin oxide-based layer, a zinc-oxide-based layer optionally a blocking layer, the functional metal layer, optionally a blocking layer, a dielectric coating located above the functional metal layer and comprising a zinc oxide-based layer, a zinc-tin oxide-based layer and optionally a protective layer.

12. The material according to claim 1, wherein the stack comprises a single functional layer.

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

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

15. The glazed unit according to claim 14, further comprising a functional coating other than the stack comprising a silver the functional metal layer, the functional coating being located: on the substrate comprising the functional metal layer, and on a face of the substrate opposite a face comprising the functional metal layer, or on a face of another substrate different from the ene substrate comprising the functional metal layer.

16. A heating or cooling device comprising a heater or cooler and an enclosure delimited by one or more walls, at least one wall of the one or more walls comprises at least one glazed unit comprising a material according to claim 1.

17. A cooling device according to claim 16, wherein the cooling device is a freezer and the at least one glazed unit consists of the material and in that the stack is located on a face of the substrate in contact with the enclosure.

18. A method comprising providing a glazed unit as a constituent element of a cooling device, a heating device or a fireproof door, the glazed unit comprising a material according to claim 1.

19. A method for preparing a material according to claim 1, wherein all the layers of the stack are deposited by magnetic-field-assisted cathode sputtering.

20. The material according to claim 8, wherein the sum of the thicknesses of all the oxide-based layers present in the dielectric coating is greater than 90% the total thickness of the dielectric coating.

Description

EXAMPLES

[0208] Stacks of thin layers defined below are deposited on substrates made of clear soda-lime glass with a thickness of 4 mm.

[0209] 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 SiO2 Si:Al 92/8% by wt 2-7 Ar 60% - O.sub.2 40% SnZnO Sn:Zn 60/40% by wt 3-4 Ar 40-50% - O.sub.2 50-60% ZnO Zn:Al 92:8% by wt 2-4 Ar 62% - O.sub.2 38% NiCr Ni:Cr (80:20% at.) 2 Ar at 100% Ag Ag 6 Ar at 100% TiO.sub.x TiOx 2 Ar 88% - O.sub.2 12% at.: atomic; wt: weight; * at 550 nm.

[0210] Table 2 below summarizes the deposition conditions of layers based on silicon oxide.

TABLE-US-00002 TABLE 2 Conditions Cp-2 Cp-3 Cp-4 Cp-5 Inv-1 Inv-2 Inv-3 Inv-4 Cpt 1 Power (kW) 25 35 45 60 60 90 60 60 Pressure (μbar) 5.2 5.1 5.2 5.4 4.5 6.1 4.3 2.3 Ar (sccm) 1100 1100 1100 1100 700 1100 700 700 O.sub.2 (sccm) 300 350 440 585 540 840 410 480 Cpt 2 Power (kW) 0 0 0 0 0 0 60 60 Pressure (μbar) — — — — — — 2.7 4.5 Ar (sccm) — — — — — — 700 700 O.sub.2 (sccm) — — — — — — 300 460 Total power (kW) 25 35 45 60 60 90 120 120 Line speed m/min 4 4 4 4 4 4 4 4 SiO2 thickness (nm) 5.6 8.4 11.0 11.5 12.0 14.8 14.8 14.2 Cpt.: Compartment

[0211] The materials Cp-1 to Cp-5 and Inv-1 and Inv-2 comprise a layer of SiO2 deposited in a single area. For the materials Inv-3 and Inv-4, the SiO2 layer is deposited in two different areas.

[0212] 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 3 below as a function of their positions with regard to the substrate carrying the stack.

TABLE-US-00003 TABLE 3 Glazed unit Cp-1 Cp-2 Cp-3 Cp-4 Cp-5 Inv-1 Inv-2 Inv-3 Inv-4 DC TiOx 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 SnZnO 30 30 30 30 30 30 30 30 30 ZnO 5 5 5 5 5 5 5 5 5 BL NiCr 0.4 0.4 0.4 0.4 0.4 0.4 0.4 0.4 0.4 FL Ag 13 13 13 13 13 13 13 13 13 BL NiCr 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 DC ZnO 5 5 5 5 5 5 5 5 5 SnZnO 30 30 30 30 30 30 30 30 30 SiO2 0 5.6 8.4 11.0 11.5 12 14.8 14.8 14.2 Sub. glass — — — — — — — — — DC: Dielectric coating; BL: Blocking layer; FL: Functional layer

[0213] A tempering type heat treatment is performed on the coated substrates at 705° C. for 180 seconds.

Evaluation of Haze and Chemical Durability

[0214] The level of haze was quantified in the following way. The tempered glass is placed on a desk tilted 20 degrees relative to 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 contrary, a sample without haze does not diffuse any light towards the observer, so it appears dark. The following assessment indicators were used: [0215] “−”: The material is very hazy, [0216] “0”: The material is hazy, [0217] “+”: The material is not hazy.

[0218] 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: [0219] ok: no pitting, the material has no defects after 56 days of testing, [0220] nok: much pitting, the material has defects and therefore does not pass the test.

[0221] The results are compiled in Table 4 below:

TABLE-US-00004 TABLE 4 Test Cp-1 Cp-2 Cp-3 Cp-4 Cp-5 Inv-1 Inv-2 Inv-3 Inv-4 Haze − − 0 0 0 + + + + HH ok ok ok ok ok ok ok ok ok TT-HH ok ok ok ok ok ok ok ok ok

[0222] In order to confirm the anti-haze effect, photographs and microscope images were taken. FIG. 1 shows two materials side by side, on the left the material Cp-1 and on the right the material Inv-2. FIG. 2 shows two microscopic images, on the left the material Cp-1 and on the right the material Inv-2. The observations are compiled in Table 5 below.

TABLE-US-00005 TABLE 5 Materials Photography Microscope Observations Cp-1 FIG. 1, left FIG. 2, left Presence of haze and numerous dendrites Inv-2 FIG. 1, right, FIG. 2, right No haze and few dendrites.

[0223] In the images of the material of the invention, no haze is observed. This is due to the strong decrease in the number of dendrites.

Study of Emissivity Degradation Based on Heat Treatment Duration

[0224] The applicant has found that the advantageous properties of the invention in terms of resistance to heat treatment are attributable to delayed degradation. The delay is illustrated by the curves in FIG. 3. These curves A, B, C, D and E represent 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 with the materials Cp-3 (Curve A), Cp-4 (Curve B), Inv-2 (Curve C), Inv-3 (Curve D) and Inv-4 (Curve E) respectively. The hollow circles on each curve represent Cp-1, and the solid circles the comparison element. The delay is observed when a layer based on silicon oxide of sufficient thickness is used (curves C, D and E).

[0225] Table 6 below highlights the delay in degradation of the solution of the invention. For this purpose, 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 Cp-3 and Cp-4 respectively, as well as the materials of the invention Inv-2, Inv-3 and Inv-4.

TABLE-US-00006 TABLE 6 Duration for 2 points Comparative Emissivity degradation Delay Cp1/Cp3 193 s/Indissociable <5 s Cp1/Cp4 193 s/Indissociable <5 s Cp1/Inv-2 193 s/210 s 17 s Cp1/Inv-3 193 s/219 s 26 s Cp1/Inv-4 193 s/218 s 25 s

[0226] For thicknesses below 12 nm, the delay is too short to be really useful. With at least 12 nm of SiO2, the time/temperature relationship during heating becomes compatible with a glass transformation, such as tempering or bending without haze, nor degraded emissivity. On the tempering and bending tools used, the glazed unit 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 glazed unit with layer may vary. A glazed unit must therefore be robust enough to accept these method variabilities. Materials Inv-2, Inv-3, and Inv-4 have this additional strength.