Method for the plasma cleaning of the surface of a material coated with an organic substance and the installation for carrying out said method

• US 20050161433A1
• Filed: 02/19/2003
• Published: 07/28/2005
• Est. Priority Date: 02/19/2002
• Status: Active Grant

• Current Assignee: Usinor
• Original Assignee: Usinor
• Inventors: Reniers, Francois, Silberberg, Eric, Michel, Eric, Buess-Herman, Claudine
• Granted Patent: US 7,674,339 B2
• Time in Patent Office: Days
• US Class Current: 216/67
• CPC Class Codes: B08B 7/0035 by radiant energy, e.g. UV, laser, light beam or the like
• CPC Class Codes: C23G 5/00 Cleaning or de-greasing metallic material by other methods; Apparatus for cleaning or de-greasing metallic material with organic solvents
• CPC Class Codes: H01J 37/32348 Dielectric barrier discharge

Abstract

The invention relates to a method of cleaning the surface of a material (4) that is coated with an organic substance. The inventive method is characterised in that it comprises the following steps, consisting in: introducing the material (4) into a treatment chamber (2), having a pressure of between 10 mbar and 1 bar therein, which is supplied with a gas stream containing at least 90 volume percent of oxygen; and generating a plasma by passing an electric discharge between the surface of the material and a dielectric-covered electrode (5a, 5b, 5c, 5d, 5e, 5f, 5g) in order to break down the organic substance under the action of the free radicals O thus produced. The invention also relates to an installation (1) that is used to carry out said method.

Claims

1. A process for cleaning the surface of a material coated with an organic substance, which process comprises the steps consisting in:

introducing said material into a treatment chamber, having a pressure of between 10 mbar and 1 bar therein, which is supplied with a gas stream containing at least 90% oxygen by volume; and

generating a plasma by passing an electric discharge between the surface of said material and a dielectric-covered electrode, so as to break down said organic substance through the action of the free radicals O. thus produced.

2. The process as claimed in claim 1, wherein the oxygen and/or ozone molecules that are formed by recombination of the free radicals O. produced in said plasma are re-dissociated.

3. The process as claimed in claim 1 or 2, wherein said re-dissociation is carried out by means of UV radiation of suitable wavelength.

4. The process as claimed in any one of claims 1 to 3, wherein the voltage applied in order to initiate the discharge is sinusoidal and has a frequency of between 10 and 100 kHz.

5. The process as claimed in any one of claims 1 to 4, wherein the energy dissipation in the discharge is less than 40 W/cm² and the voltage applied in order to initiate the discharge is less than 4.4 kV.

6. The process as claimed in any one of claims 1 to 5, wherein the material is in the form of a running strip and the various steps of the process are carried out continuously by means of installations placed in succession along the path of the running strip.

7. The process as claimed in claim 6, wherein one of the faces of said strip is treated followed in succession by the other.

8. The process as claimed in one of claims 1 to 7, wherein said material to be treated is a metallic material.

9. The process as claimed in claim 8, wherein said metallic material is a carbon steel.

10. The process as claimed in either of claims 8 and 9, which is carried out in order to degrease the surface of metallic materials, prior to a coating being deposited on said surface.

11. An installation for carrying out the process as claimed in any one of claims 6 to 10, which comprises at least one module comprising a treatment chamber (2), means for setting the pressure inside said chamber to a value between 10 mbar and 1 bar, means (3) for making said grounded strip (4) run through said chamber, a series of dielectric-covered electrodes (5a, 5b, 5c, 5d, 5e, 5f, 5g) placed so as to face that surface of said strip (4) to be treated, these electrodes (5a, 5b, 5c, 5d, 5e, 5f, 5g) being connected to a sinusoidal high-voltage generator (6), means for supplying said chamber (2) with gas and means for extracting from said chamber the gases resulting from the decomposition of the organic substance coating the strip (4).

12. The installation as claimed in claim 11, which comprises a succession of an even number of said modules (10, 11, 12, 13), through which said strip (14) runs in succession, exposing in turn one of its faces to the electrodes of said modules (10, 11, 12, 13).

13. The installation as claimed in claim 11 or 12, which furthermore includes UV emission lamps (7a, 7b, 7c, 7d, 7e, 7f) placed between said electrodes (5a, 5b, 5c, 5d, 5e, 5f, 5g).