# US 4,400,246 A · Process for applying barrier layer anodic coatings

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- Number: US 4,400,246 A
- Document ID: US4400246A
- Status: Granted
- Kind: A
- Application number: 06/392,840
- Filed: 1982-06-28
- Granted: 1983-08-23
- Earliest claimed: 1982-06-28
- Assignees: International Business Machines Corporation
- Inventors: George A. Condas; Saad K. Doss
- Web page: https://patentgrep.com/patent/US4400246A

## CPC

- C25D 11/04: of aluminium or alloys based thereon
- C25D: PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR

## Abstract

A barrier anodizing process for an aluminum alloy substrate employs an anodizing current having a density between 20 and 300 milliamps/cm.sup.2 to produce a 300 volt barrier layer in respectively 60 and 4 second

## Claims

### Claim 1

A method of providing a barrier layer on the surface of an aluminum substrate comprising the steps of barrier anodizing said substrate at an anodizing current density of at least 20 milliamperes/cm.sup.2 for a very short period of time not to appreciably exceed the barrier formation time, said barrier anodizing being conducted in an acidic bath having a pH of between 5 and 7.

### Claim 2 (depends on 1)

A method in accordance with claim 1 in which said barrier anodizing current is maintained between 20 and 300 milliamperes/cm.sup.2.

### Claim 3 (depends on 1)

A method in accordance with claim 1 in which the voltage in said barrier anodizing is maintained between 150 and 500 volts.

### Claim 4 (depends on 2)

A method in accordance with claim 2 in which said barrier anodizing period of time is between 60 seconds and 4 seconds.