Heating device comprising a glazing substrate coated on both sides

Abstract

A heating device equipped with a chamber defining a cavity, includes a door or wall incorporating a multiple glazing, the glazing including at least one transparent substrate coated on each face with a stack of thin layers, namely: on a first face, turned toward the cavity, a first stack that reflects heat essentially by virtue of one or more functional layers based on indium tin oxide; and on the other face, turned toward the exterior of the device, a second stack that reflects heat essentially by virtue of one or more functional layers based on a metal chosen from gold or silver.

Claims

1. A heating device equipped with a chamber defining a cavity, said device comprising a door or wall incorporating a multiple glazing, said glazing comprising at least one transparent substrate coated on each face with a stack of thin layers, namely: on a first face, turned toward said cavity, a first stack that reflects heat essentially by virtue of one or more functional layers based on indium tin oxide; and on a second face, turned toward the exterior of the device, a second stack that reflects heat essentially by virtue of one or more functional layers based on a metal chosen from gold or silver.

2. The heating device as claimed in claim 1, wherein the first stack is positioned, in the glazing, in contact with the cavity of the heating device.

3. The heating device as claimed in claim 1, wherein the first stack comprises, as functional layer, an indium tin oxide the atomic percentage of Sn of which in the oxide is comprised in a range extending from 5 to 70%.

4. The heating device as claimed in claim 1, wherein the first stack comprises as functional layer a layer of indium tin oxide comprising a proportion by weight of about 85 to 95% indium oxide and about 15 to 5% tin oxide.

5. The heating device as claimed in claim 1, wherein the first stack comprises, in succession, starting from the substrate: at least one underlayer of a dielectric compound; an ITO functional layer; and at least one overlayer of a dielectric compound.

6. The heating device as claimed in claim 5, wherein the at least one underlayer of a dielectric compound is chosen from silicon nitride, silicon oxide or zinc tin oxide; and the at least one overlayer of a dielectric compound is chosen from silicon nitride, silicon oxide, or zinc tin oxide.

7. The heating device as claimed in claim 1, wherein the first stack comprises, in succession, starting from the substrate: at least one underlayer of a dielectric compound; a first ITO functional layer; an intermediate layer of a dielectric compound; a second ITO functional layer; and at least one overlayer of a dielectric compound.

8. The heating device as claimed in claim 7, wherein the at least one underlayer of a dielectric compound is chosen from silicon nitride, silicon oxide or zinc tin oxide; the intermediate layer of a dielectric compound is chosen from silicon oxide, silicon nitride or zinc tin oxide; and the at least one overlayer of a dielectric compound is chosen from silicon nitride, silicon oxide, or zinc tin oxide.

9. The heating device as claimed in claim 1, wherein the second stack comprises 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 silver-based layer is placed between two dielectric coatings.

10. The heating device as claimed in claim 1, wherein the second stack has a normal emissivity, measured according to standard EN 12898, lower than or equal to 10%.

11. The heating device as claimed in claim 1, wherein the glazing is a multiple glazing comprising two, three or four substrates.

12. The heating device as claimed in claim 1, wherein at least the coated substrate of the stack is curved and/or tempered.

13. The heating device as claimed in claim 1, wherein the glazing comprises at least one additional heat-reflecting coating deposited on at least one other constituent substrate of the glazing.

14. The heating device as claimed in claim 13, wherein said additional heat-reflecting coating is placed on a third face and/or on a fifth face of the glazing, from the interior to the exterior of said heating device.

15. The heating device as claimed in claim 13, wherein said additional heat-reflecting coating comprises, as functional layer, a transparent conductive oxide chosen from indium tin oxide or a tin oxide that is doped in order to make it electrically conductive or wherein said additional heat-reflecting coating is a stack comprising, as functional layer, at least one silver layer.

16. The heating device as claimed in claim 1, wherein the metal is silver.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Various embodiments of the present invention are presented below with reference to FIG. 1 which is appended hereto:

(2) FIG. 1 illustrates three examples of heating devices comprising multiple glazings according to the invention, a glazing comprising 4 substrates (configurations I to IV), a triple glazing (configuration V) and a double glazing (configuration VI).

(3) FIG. 2 illustrates multiple glazings according to comparative configurations.

EXAMPLES

(4) According to the invention, the thin-layer stacks defined below were deposited on a first substrate made of 4 mm thick clear soda-lime glass.

(5) On a first face of the substrate, a stack according to example 1 of patent application WO2015/033067 was deposited.

(6) More precisely, the following stack A was deposited by AC magnetron cathode sputtering on a 4 mm thick clear soda-lime-silica glass substrate:

(7) Glass/SiN.sub.x (2 nm)/SiO.sub.2 (34 nm)/ITO (118 nm)/SiN.sub.x (6 nm)/SiO.sub.2 (65 nm)/TiO.sub.2 (3 nm).

(8) The numbers between parentheses correspond to the physical thicknesses deposited for each layer, expressed in nanometers.

(9) The layers of silicon oxide and of silicon nitride were deposited, using aluminum-doped (to 8 at %) silicon targets, in an argon plasma with addition of oxygen and nitrogen, respectively. The ITO layers were deposited using ITO targets in an argon plasma. The ITO layer consisted of a mixture of indium (III) oxide (In2O3) and tin (IV) oxide (SnO2), the proportion by weight of the first being about 90% and the proportion by weight of the second about 10%. The SiN.sub.x barrier layer was deposited at a pressure of 2.0 bar. The normal emissivity of this stack, such as measured according to standard FR-EN 12898, was 18%.

(10) On the second face of the substrate, the following stack B, which included a silver functional layer, and the normal emissivity of which was 3%, was deposited using conventional cathode sputtering deposition techniques:

(11) Glass/SiN.sub.x (30 nm)/ZnO (5 nm)/NiCr (0.5 nm)/Ag (12 nm)/NiCr (0.5 nm)/ZnO (5 nm)/SiN.sub.x (30 nm)/TiO.sub.2 (3 nm).

(12) This substrate coated on its two faces was then installed into the wall of an oven, in association with one or more other glazing substrates as indicated in the configurations illustrated in FIG. 1.

(13) According to the invention, the substrate described above was positioned in direct contact with the chamber of the oven, in such a way that the first stack, the functional layer of which was made of ITO, was turned toward said chamber (face 1 of the glazing) and the second stack, the functional layer of which was made of silver, was positioned on face 2 of the constituent glazing of the wall of the oven.

(14) In configurations I to IV, the wall comprises four glazing substrates:

(15) a first substrate according to the invention such as described above; and then three successive glazing substrates, the faces of which were successively numbered from 2 to 8 (see FIG. 1).

(16) In configuration I, the two intermediate substrates were examples of the glazing product sold by the AGC under the reference Planibel G. They each comprised, on one face, a coating C, deposited by pyrolysis-CVD, consisting of a layer of fluorine-doped tin oxide. The face comprising the coating was turned toward the cavity of the oven (i.e. faces 3 and 5 of the wall).

(17) Configuration III was identical to configuration II except that the second substrate was coated with no stack of thin layers.

(18) Configuration IV was identical to configuration II except that the third substrate was coated with no stack of thin layers.

(19) In configuration V, the wall comprised only three glazing substrates: a first substrate according to the invention such as described above, then two successive glazing substrates, the faces of which were successively numbered from 2 to 6. The intermediate substrate was a Planibel G and the coating was positioned on face 3 of the glazing.

(20) In configuration VI, the wall comprised only two glazing substrates: a first substrate according to the invention such as described above, then a substrate that was coated with no stack of thin layers.

(21) Subsequently, comparative configurations were prepared, shown in FIG. 2, in which configurations the various heat-reflecting stacks were positioned on other faces of the quadruple glazing. More specifically: In configuration VII, coating C (Planibel) was positioned on faces 1 and 3 and stack A (ITO) on faces 5 and 6 of the glazing. In configuration VIII, stack C was positioned on faces 1 and 5 and stack A on faces 3 and 4 of the glazing. In configuration IX, stack A was positioned on faces 1 and 2 and coating C on faces 3 and 5 of the glazing. In configuration X, stack A was positioned on faces 1, 3 and 5 of the glazing. In configuration XI, stack A was positioned on faces 1 and 2 and coating C on face 5 of the glazing.

(22) Two configurations according to the teaching of patent application EP1293726A2, comprising transparent-conductive-oxide layers deposited by pyrolysis-CVD on face 1 of the glazing, were also prepared by way of comparative examples. Specifically, two commercial glazing substrates comprising, on one face, a layer of SnO2:F deposited by CVD-pyrolysis, were used by way of first substrate making contact with the cavity: the Planibel glazing product described above; and a glazing product sold by NSG under the reference TECO, in which the heat-reflecting stack has an emissivity of 12% (coating D).
More specifically: In configuration XII, the silver-based stack B described above was deposited on a Planibel substrate, on the face not covered with the pyrolytic stack. This comparative substrate was substituted for the first substrate in the four-substrate wall of example II, the pyrolytic functional layer (coating C) being turned toward said chamber (face 1 of the glazing). In configuration XIII, the silver-based stack B described above was deposited on that face of the TEC product which was not covered with the pyrolytic stack. This comparative substrate was substituted for the first substrate in the four-substrate wall of example II, the pyrolytic functional layer (coating D) being turned toward said chamber (face 1 of the glazing).

(23) The chamber equipped with the various doors was then heated to a temperature of about 425 C. to 430 C. and the temperatures between each constituent substrate of the wall were measured using thermocouples in a conventional manner. The results are given in table 1 below:

(24) In table 1, a face coated with the stack A (comprising the ITO functional layer and of 18% emissivity) is denoted A, a face coated with the stack B (comprising the silver functional layer) is denoted B, a face coated with the coating C (comprising the pyrolytic SnO.sub.2:F layer of 16% emissivity) is denoted C, a face coated with the coating D (comprising the pyrolytic SnO.sub.2:F layer of 12% emissivity) is denoted D and an uncoated face is denoted X.

(25) TABLE-US-00001 TABLE 1 Door Intermediate glass exterior Tmax Tmax Tmax Cavity trial F1 F2 F3 F4 F5 F6 F7 F8 Tmax door (S1-S2) (S2-S3) (S3-S4) Tav I A B C X C X X X 65 133 135 99 431 II A B X X C X X X 63 118 130 84 430 III A B C X X X X X 67 108 119 69 428 IV A B X X X X X X 65 146 119 71 421 V A B C X X X 65 175 102 NA 423 VI A B X X 70 158 NA NA 423 VII C X C X A A X X 67 236 152 108 426 VIII C X A A C X X X 71 241 161 102 427 IX A A C X C X X X 68 233 147 86 424 X C X C X C X X X 71 239 162 103 425 XI A A X X C X X X 68 231 158 92 423 XII C B X X C X X X 60 217 169 76 426 XIII D B X X C X X X 62 131 146 77 429

(26) In table 1, Tmax door indicates the maximum temperature measured on the door exterior, Tmax S1-S2 the maximum temperature measured in the space between substrate 1 and substrate 2, Tmax S2-S3 the maximum temperature measured in the space between substrate 2 and substrate 3, and Tmax S3-S4 the maximum temperature measured in the space between substrate 3 and substrate 4.

(27) The results given in table 1 demonstrate the advantages of the present invention: examples I to IV according to the invention comprising a wall the first substrate of which is coated, on the face turned toward the cavity of the oven, with a coating comprising an ITO functional layer and on the other face with a coating comprising a silver functional layer allowed said cavity to be better insulated, as the substantial decrease in the temperature in the space between said first substrate and the second substrate shows. The decrease in temperature between the two first substrates, which decrease was observed by virtue of the particular configuration of the stacks present on the first substrate, thus allows the cavity to be better insulated, this resulting in a number of advantages: In the case of a pyrolytic oven, such an improvement in insulation allows the heating required to maintain the high temperatures required for said pyrolysis to be limited. During normal use of the oven to cook food (i.e. at a maximum temperature of 240 C.), this better insulation allows the power consumption of the oven to be significantly decreased and therefore the energy rating thereof to be improved. Furthermore, the ventilation used to cool the glazing portions of the wall may be greatly decreased or may even no longer be required.

(28) According to another advantage, it becomes possible according to the invention to use, in such walls, stacks the functional layer of which is made of silver and that are not specifically configured to resist heat, because of the substantial decrease in the temperature seen by said coatings in phases of cleaning the oven by pyrolysis. Furthermore, the use of a wall according to the invention could allow the configuration of the door to be simplified (3- rather than 4-pane configuration), as example IV shows, while ensuring the required safety levels.

(29) Lastly, in the case of a conventional (non-pyrolytic) oven, the walls of which comprise only two or three glazing substrates, it may be seen that entirely suitable, and even improved, insulation levels may be obtained.

(30) Comparison of examples II, XII and XIII shows that only the particular combination of coatings according to the invention allows such a result to be obtained. In particular, very surprisingly and unexpectedly, it may be seen that the replacement of a tin-based pyrolytic TCO coating with an ITO-based stack of layers according to the invention allows the insulation properties of the wall to be significantly improved, even though the emissivity measured for said tin-based pyrolytic TCO coatings is lower than that of said ITO-based stack of layers.

(31) Examples I, II and III furthermore show, if compared with example IV, that the thermal insulation of the cavity may be further improved if an additional heat-reflecting coating, of the TCO (SnO2:F or ITO) type or a silver-containing stack, is placed on face 3 and/or 5 of the glazing, and in particular on face 3 of the glazing.