Claims
- 1. A process for the production of insulated metal substrates having an aluminium base, an insulant constituted by an alumina film obtained by anodization of said base on at least one of its faces and at least one metallic film for transformation by chemical etching into a conductive network, wherein the alumina film is formed of a uniform compact non-porous amorphous zone on at least one surface of the aluminium base and a porous layer with a rough outer surface comprising the steps of: subjecting at least one of the faces of the aluminium base to treatment in a porous anodization bath; followed by treatment of the at least one porous anodized face in a barrier anodization bath.
- 2. Process according to claim 1, wherein in the step of subjecting the at least one of the faces to the porous anodization bath the bath comprises an electrolyte selected from the group of acids consisting of sulphuric acid, sulphosalicylic acid, chromic acid, phosphoric acid and any combination of at least two of said acids.
- 3. Process according to claim 2, wherein the porous anodization bath is formed by sulphosalicylic acid.
- 4. Process according to claim 1, wherein in the step of subjecting the at least one of the faces to the anodization bath the bath comprises an electrolyte selected from the group of salts in aqueous solution consisting of ammonium tartrate, ammonium borate, potassium chromate, ammonium citrate and any combination of at least two of said salts.
- 5. Process according to claim 4, wherein the anodization bath is formed by ammonium borate.
- 6. Process according to claim 1, wherein the metallic film is obtained by the steps of physical vacuum deposition and then electrolytic recharging.
- 7. Process according to claim 1, wherein the compact zone is of about 500 nm to about 1200 nm and the treatment in the porous anodization bath results in the porous layer being bout 5,000 nm to about 50,000 nm with a rough outer surface.
Parent Case Info
This is a divisional of copending application Ser. No. 07/506,108, filed Apr. 9, 1990.
Foreign Referenced Citations (1)
Number |
Date |
Country |
2206451 |
Jan 1989 |
GBX |
Divisions (1)
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Number |
Date |
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Parent |
506108 |
Apr 1990 |
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