Substrate coated with a stack of functional layers having improved mechanical properties

Abstract

A transparent substrate provided with a stack of thin layers includes an alternation of n functional layers having reflection properties in the infrared region and/or in solar radiation with n2 and of n+1 coatings including one or more dielectric layers, so that each functional layer is positioned between two coatings, the coatings and the functional layers are numbered according to their position with respect to the transparent substrate, the lower coating 1 is placed above the transparent substrate and below the functional layer 1, the intermediate coatings 2 to n are placed between two functional layers and the upper coating n+1 is placed above the functional layer n, wherein at least one of the upper or intermediate coatings 2 to n+1 includes at least one barrier coating including at least two barrier layers, one layer including silicon and one layer based on aluminum nitride.

Claims

1. A transparent substrate provided with a stack of thin layers comprising an alternation of n functional layers having reflection properties in the infrared region and/or in solar radiation with n2 and of n+1 coatings comprising one or more dielectric layers, so that each functional layer is positioned between two coatings, the coatings and the functional layers are numbered according to their position with respect to the transparent substrate, a lower coating 1 is placed above the transparent substrate and below the functional layer 1, the intermediate coatings 2 to n are placed between two functional layers and an upper coating n+1 is placed above the functional layer n, wherein at least one of the upper or intermediate coatings 2 to n+1, comprises at least one barrier coating comprising at least two barrier layers, one layer of the at least two barrier layers comprising silicon and another one layer of the at least two barrier layers based on aluminum nitride, said one layer comprising silicon being in contact with said other layer based on aluminum nitride.

2. The transparent substrate as claimed in claim 1, wherein the stack comprises two functional layers alternating with three lower, intermediate and upper coatings.

3. The transparent substrate as claimed in claim 1, wherein the barrier coating comprising at least two layers comprises three layers, two layers comprising silicon located above and below a layer based on aluminum nitride.

4. The transparent substrate as claimed in claim 1, wherein the layer based on aluminum nitride is located between a functional layer and the layer comprising silicon.

5. The transparent substrate as claimed in claim 1, wherein the barrier coating comprising at least two layers, one layer comprising silicon and one layer based on aluminum nitride, is located in the intermediate coating n.

6. The transparent substrate as claimed in claim 5, wherein, in the intermediate coating n, the layer based on aluminum nitride is located above the functional layer n1 and below a layer comprising silicon.

7. The transparent substrate as claimed in claim 1 wherein each lower, intermediate or upper coating comprises at least one barrier coating comprising at least one barrier layer.

8. The transparent substrate as claimed in claim 1, characterized in that wherein at least one functional layer is surmounted by a blocking layer.

9. The transparent substrate as claimed in claim 8, wherein each functional layer is surmounted by a blocking layer.

10. The transparent substrate as claimed in claim 1, wherein at least one lower, intermediate or upper coating comprises at least one stabilizing layer.

11. The transparent substrate as claimed in claim 10, wherein each functional layer is above a lower or intermediate coating, the upper layer of which is a stabilizing layer, and/or below an intermediate or upper coating, the lower layer of which is a stabilizing layer.

12. The transparent substrate as claimed in claim 11, wherein the stabilizing layer is based on zinc oxide.

13. The transparent substrate as claimed in claim 1, characterized in that wherein at least one lower, intermediate or upper coating comprises at least one absorbing layer.

14. The transparent substrate as claimed in claim 1, wherein the upper coating n+1 comprises, as upper layer, a layer based on SnZnO or TiO.sub.2.

15. The transparent substrate as claimed in claim 14, wherein the layer based on SnZnO or TiO.sub.2 has a thickness of less than 5 nm.

16. The transparent substrate as claimed in claim 1, wherein the layer of aluminum nitride comprises one or more metals or semimetals other than aluminum with a ratio of the aluminum to all the other metals or semimetals, as atomic percentage, in the layers of aluminum nitrides of greater than 1.

17. The transparent substrate as claimed in claim 16, wherein the ratio is greater than 9.

18. The transparent substrate as claimed in claim 1, wherein a total the thickness of the at least one layer based on aluminum nitride included in an intermediate or upper coating represents from 20 to 80% of the total thickness of said intermediate or upper coating.

19. The transparent substrate as claimed in claim 18, wherein the total thickness of the at least one layer based on aluminum nitride included in an intermediate or upper coating represents from 30 to 60% of the total thickness of said intermediate or upper coating.

20. The transparent substrate as claimed in claim 1, comprising a stack, defined starting from the transparent substrate, comprising: at least one barrier coating, at least one stabilizing layer, at least one functional layer, optionally a sacrificial layer, at least one stabilizing layer, at least one barrier coating into which at least one absorbing layer is optionally intercalated, at least one stabilizing layer, at least one functional layer, optionally a sacrificial layer, at least one stabilizing layer, at least one barrier coating.

21. A glazing comprising a transparent substrate as claimed in claim 1, wherein the glazing is in the form of a laminated glazing, of an asymmetric glazing or of a multiple glazing of the double glazing type.

22. The transparent substrate as claimed in claim 1, wherein at least one of the intermediate coatings 2 to n comprises at least one barrier coating comprising at least two barrier layers, one layer of the at least two barrier layers comprising silicon and another one layer of the at least two barrier layers based on aluminum nitride.

Description

EXAMPLES

I. Description of the Glazings Tested

(1) The stacks are deposited on substrates made of clear soda-lime-silica glass with a thickness of 4 mm.

(2) In all the examples of the invention: the functional layers are silver (Ag) layers, the blocking layers are made of alloy of nickel and chromium (NiCr), the stabilizing layers are made of zinc oxide (ZnO), and absorbing layers are made of nickel-chromium nitride (NiCrN).

(3) The stacks of the invention comprise at least one barrier coating comprising at least two barrier layers, one layer based on silicon nitride (Si.sub.3N.sub.4) and one layer based on aluminum nitride (AlN), at a specific position. Preferably, the two barrier layers comprising at least one layer based on silicon nitride (Si.sub.3N.sub.4) and one layer based on aluminum nitride (AlN) of the barrier coating are in direct contact.

(4) The other barrier coatings of the stacks according to the invention, according to the reference example, can be composed solely of silicon nitride (Si.sub.3N.sub.4).

(5) In these examples, the nature of the barrier coating and its position were varied.

(6) The successive depositions of the layers of the stack are carried out by cathode sputtering assisted by a magnetic field. The deposition plant comprises at least one sputtering chamber provided with cathodes equipped with targets made of appropriate materials under which the substrate successively passes. The power densities, the rates of forward progression of the substrate, the pressure and the choice of the atmosphere are adjusted in a known way in order to obtain the desired layer thicknesses. The glazings tested comprise the stacks described in the table below.

(7) TABLE-US-00001 Positioning Ref. Ex. Inv. 1 Inv. 2 Inv. 3 Inv. 4 Inv. 5 Substrate Glass nm nm nm nm nm nm Lower Si.sub.3N.sub.4 30 30 30 30 30 30 coating 1 ZnO 6 6 6 6 6 6 Functional Ag 7 7 7 7 7 7 layer 1 NiCr 0.8 0.8 0.8 0.8 0.8 0.8 Intermediate ZnO 6 6 6 6 6 6 coating 2 AlN 20 20 Si.sub.3N.sub.4 34 34 14 34 48 48 Si.sub.70Al.sub.30N NiCrN 0.9 0.9 0.9 0.9 Si.sub.3N.sub.4 34 34 34 14 AlN 20 20 ZnO 6 6 6 6 6 6 Functional Ag 18 18 18 18 18 18 layer 2 NiCr 1 1 1 1 1 1 Upper ZnO 6 6 6 6 6 6 coating 3 AlN 8 Si.sub.3N.sub.4 16 8 16 16 16 16 SnZnO 3 3 3 3 3 3

(8) The character - means that the layer does not exist. The reference example does not comprise a layer based on aluminum nitride.

(9) The example of the invention 1 comprises a barrier coating comprising a layer based on aluminum nitride in the upper coating 3 located above the final functional layer. In this embodiment, which is not preferred, the layer based on aluminum nitride is not included between two functional layers.

(10) The examples of the invention 2, 3 and 5 comprise a barrier coating comprising a layer based on aluminum nitride in the intermediate coating 2 located between the two functional layers.

(11) The glazings, once provided with the stack of layers, can be subjected to a heat treatment in order to simulate a tempering under the normal conditions in the field. The glazings are then subjected to a heat treatment for approximately 8 minutes at a temperature of approximately 650 C., followed by cooling in the ambient air (approximately 20 C.).

II. Erichsen Brush Test (EBT)

(12) The different glazings comprising the substrates described above were subjected to the Erichsen Brush Test (EBT) for 100 or 300 cycles, before and after tempering. This test consists in rubbing the stack using a brush consisting of bristles made of polymer material, the stack being covered with water. A glazing is regarded as satisfying the test if no mark is visible to the naked eye.

(13) The test before tempering gives a good indication with regard to the ability of the glazing to be scratched during a washing operation. The test after tempering gives a good indication with regard to the propagation of the cracks after heat treatment.

(14) The following assessment indicators were used: +++: no scratch, ++: 1 or 2 fine and noncontinuous scratches, +: a few fine and noncontinuous scratches, 0: noncontinuous scratches, : numerous fine scratches, : even more numerous fine scratches, : highly scratched.

(15) The glazings, the evaluation conditions and the assessment indicators are summarized in the table below.

(16) TABLE-US-00002 Tempering Before After Cycles 100 300 100 300 Reference ++ + Inv. 1 ++ + 0 Inv. 2 +++ +++ +++ ++ Inv. 3 +++ +++ +++ +++

(17) The stacks of the invention make it possible to sufficiently relax the compressive stresses and thus to eliminate the disadvantages related to the ability of such stacks to be scratched and to the propagation of said scratches subsequent to a heat treatment, this more particularly being the case when the barrier layer comprising aluminum nitride is located in the intermediate coating 2.

III. Erichsen Scratch Test

(18) The different glazings comprising the substrates described above were subjected to the Erichsen Scratch Test (EST) after having been subjected to tempering under the conditions defined above. This test consists in recording the value of the force, in newtons, necessary in order to produce a scratch in the stack when the test is carried out (Van Laar tip, steel ball). The test was carried out at 0.5N. The width of the scratches (w) was measured in m.

(19) TABLE-US-00003 Width of the Width of the % of scratch exploded scratch corroded Glazing before tempering after tempering scratch Reference 15 40 50% Inv. 1 17 60 55% Inv. 2 12 15 10% Inv. 3 15 30 20%

(20) A corroded and exploded (propagation of the corrosion into the regions adjacent to the scratch) scratch appears very visible in transmission and exhibits a bright yellow appearance. The stacks comprising the specific barrier coating of the invention located in the intermediate coating 2 show a less visible scratch after tempering. This is because the barrier coating prevents corrosion of the scratch and the propagation of this corrosion into the regions adjacent to the scratch (known as exploding). The visibility of the scratch is the same before and after tempering. This tendency is even more marked when the layer based on aluminum nitride is located above a stabilizing layer and below a layer of Si.sub.3N.sub.4.

(21) These examples clearly show that the barrier coating comprising in particular a layer based on aluminum nitride has to be inserted in a specific fashion into stacks in order to limit the ability of said stacks to be scratched or, in the even of scratching, the visibility of said scratches.