Light metal anodization

Abstract

Using aqueous electrolytes containing complex fluorides or oxyfluorides such as fluorozirconates, fluorotitanates, and fluorosilicates, articles containing light metals such as magnesium and aluminium may be rapidly anodized to form protective surface coatings. White coatings may be formed on aluminium articles using pulsed direct current or alternating current. When the article to be anodized is comprised of magnesium, pulsed direct current having a relatively low average voltage is preferably used.

Description

[0001] This application is a continuation-in-part of Ser. No. 10 / 162,965, filed June 5, 2002, which is a continuation-in-part, of Ser. No. 10 / 033,554, filed October 19, 2001, which is a 2001 Continuation in part of application Ser. No. 09 / 968,023 filed October 2. field of invention

[0002] This invention relates to the anodizing of light metals such as magnesium and aluminum to provide corrosion, heat and wear resistant coatings. The invention is particularly useful for forming white anodized coatings on aluminum substrates. Background of the invention

[0003] Magnesium, aluminum and their alloys have found various industrial applications. However, due to the reactivity of these light metals and their propensity for corrosion and environmental degradation, it is necessary to provide an adequate corrosion-resistant and protective coating to the exposed surfaces of these metals. In addition, such coatings should be abrasion resistant so that the coating remains intact duri...