THIN LAYER DEPOSITION PROCESS

Abstract

A process for obtaining a material includes a substrate coated with a photocatalytic coating, the process including depositing on the substrate, by sputtering, a stack of thin layers successively including a first layer of titanium metal having a thickness of from 1 to 3 nm, an intermediate layer of at least partially oxidized titanium having a thickness of from 0.5 to 5 nm, and a second layer of titanium metal having a thickness of from 2 to 5 nm; and oxidizing the stack, with the aid of a heat treatment by laser radiation, wherein the stack is in contact with an oxidizing atmosphere.

Claims

1. A process for obtaining a material comprising a substrate coated with a photocatalytic coating, said process comprising: depositing on said substrate, by sputtering, a stack of thin layers successively comprising a first layer of titanium metal having a thickness of from 1 to 3 nm, an intermediate layer of at least partially oxidized titanium having a thickness of from 0.5 to 5 nm, and a second layer of titanium metal having a thickness of from 2 to 5 nm; and oxidizing said stack, with the aid of a heat treatment by laser radiation, wherein the stack is in contact with an oxidizing atmosphere.

2. The process as claimed in claim 1, wherein the substrate is a glass sheet.

3. The process as claimed in claim 1, wherein the intermediate layer of at least partially oxidized titanium is a layer of TiO.sub.x, x being greater than or equal to 1.8.

4. The process as claimed in claim 1, wherein the intermediate layer of at least partially oxidized titanium is a layer of TiO.sub.2.

5. The process as claimed in claim 1, wherein the intermediate layer of at least partially oxidized titanium has a thickness of from 0.5 to 2 nm.

6. The process as claimed in claim 1, wherein the first layer of titanium metal and the second layer of titanium metal each have a thickness of from 1 to 5 nm.

7. The process as claimed in claim 1, wherein the first layer of titanium metal has a thickness of from 1 to 2 nm and the second layer of titanium metal has a thickness of from 2 to 4 nm.

8. The process as claimed in claim 1, wherein a run speed of the substrate during the heat treatment by laser radiation is greater than or equal to 2 m/min.

9. The process as claimed in claim 1, wherein the laser radiation has a wavelength of between 800 and 1300 nm.

10. The process as claimed in claim 1, wherein a power per unit area of the laser radiation at the intermediate layer is greater than or equal to 20 kW/cm.sup.2.

11. The process as claimed in claim 1, wherein the laser radiation results from at least one laser beam forming a line that simultaneously radiates all or some of the width of the substrate.

12. A material comprising a substrate coated with a stack of thin layers successively comprising a first layer of titanium metal having a thickness of from 1 to 3 nm, an intermediate layer of at least partially oxidized titanium having a thickness of from 0.5 to 5 nm, and a second layer of titanium metal having a thickness of from 2 to 5 nm.

13. The material as claimed in claim 12, wherein the intermediate layer of at least partially oxidized titanium has a thickness of from 0.5 to 2 nm.

14. The material as claimed in claim 12, wherein the first layer of titanium metal has a thickness of from 1 to 2 nm and the second layer of titanium metal has a thickness of from 2 to 4 nm.

15. The material as claimed in claim 12, wherein the intermediate layer of at least partially oxidized titanium is a layer of TiO.sub.2.

16. The process as claimed in claim 9, wherein the laser radiation has a wavelength of between 800 and 1100 nm.

17. The process as claimed in claim 10, wherein the power per unit area of the laser radiation at the intermediate layer is greater than or equal to 30 kW/cm.sup.2.

Description

EXAMPLES

[0039] Three samples (I1 to I3) comprising a photocatalytic coating, obtained by the process according to the invention, were prepared as follows.

[0040] A stack of thin layers consisting successively of a first layer of titanium metal, an intermediate layer of titanium oxide TiO.sub.2, and a second layer of titanium metal is deposited on a clear soda-lime-silica glass substrate.

[0041] The layers of titanium metal are deposited by sputtering using a titanium target in an argon plasma. The intermediate layer of titanium oxide TiO.sub.2 is also deposited by sputtering using a TiO.sub.2 target in an argon plasma.

[0042] The samples are treated using an in-line laser, obtained by juxtaposition of several individual lines, emitting radiation with a wavelength of 1030 nm, past which the coated substrate runs translationally. The samples I1 and I2 were treated with a run speed of 2 m/min, whilst the sample I3 was treated with a run speed of 3 m/min.

[0043] By way of comparison, the samples (R1 to R3) comprising a photocatalytic coating obtained by laser treatment of a coating consisting respectively of a single 5 nm layer of titanium metal, of a 6 nm layer of titanium oxide surmounted by a 4 nm layer of titanium metal, and of a 6 nm layer of titanium metal surmounted by a 6 nm layer of titanium oxide were prepared. The samples (R1 to R3) were treated with a run speed of 2 m/min.

[0044] The stitching phenomenon was evaluated in reflection on a black background and in transmission on a white background by an entrained observer for each of the samples treated.

[0045] Table 1 below summarises the features of each of the samples and the results of the evaluation of the stitching phenomenon. The observations of the stitching phenomenon were denoted as follows: x indicates visible marks, indicates very light marking visible after searching, and indicates an absence of visible marks.

TABLE-US-00001 Stack (nm) Treatment Stitching Sample Ti TiO.sub.2 Ti rate (m/min) Reflection Transmission R1 5 2 X X R2 6 4 2 X R3 6 6 2 Not measured (substantial delamination) I1 2 3 3 2 I2 2 1.6 3.5 2 I3 1.5 1.5 3.5 3

[0046] The photocatalytic activity was also measured for each of the samples. The samples according to the invention have a photocatalytic activity that is comparable to that of the references R1 and R2.