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Protective Oxide Coating on Aluminum and Magnesium Alloys

IP.com Disclosure Number: IPCOM000122085D
Original Publication Date: 1991-Oct-01
Included in the Prior Art Database: 2005-Apr-04
Document File: 1 page(s) / 44K

Publishing Venue

IBM

Related People

Brand, JL: AUTHOR [+3]

Abstract

Bare metal parts are prone to corrosion. In order to prevent corrosion on metals, chemical coatings are generally applied to aluminum and magnesium parts. We propose a method which provides a protective coating on aluminum and magnesium alloys and eliminates the need for a chromate or other chemical conversion coating process.

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Protective Oxide Coating on Aluminum and Magnesium Alloys

      Bare metal parts are prone to corrosion.  In order to prevent
corrosion on metals, chemical coatings are generally applied to
aluminum and magnesium parts.  We propose a method which provides a
protective coating on aluminum and magnesium alloys and eliminates
the need for a chromate or other chemical conversion coating process.

      Exposing aluminum and magnesium alloys to pure, deionized hot
water followed by hot air drying forms a protective oxide coating on
the metal.  This oxide layer protects the metal from further
corrosion.  We have been able to successfully use this water-grown
oxide film as a replacement for chromate conversion coatings on
aluminum alloys.  There also have been promising initial results on
magnesium alloys.

      Most aluminum and magnesium parts go through expensive chemical
coating operations.  We have found that bare aluminum and magnesium
parts which are cleaned in hot, deionized water grow a thick,
protective oxide coating. This protective oxide layer has ALWAYS
passed two stringent coatings tests - the tape test for adherence and
the contact stain test for corrosion.  Alternative chemical coatings
often fail these tests.

      A typical cycle used to grow a 80 nm thick oxide layer totals
10 minutes with 3 tanks of 160 degree Fahrenheit water, 1 tank of 180
degree Fahrenheit water, and a drying tank with 250 degree Fahrenheit
HEPA filtered air.  The r...