Importance

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Abstract

Apparatus and method for producing metallic flake having an environmental coating for use in oxidative and corrosive atmospheres. Fluidized bed techniques are utilized to perform a controlled oxidation of metallic particles that include aluminum. The fluidized techniques permit the formation of a thin, outer shell of alumina over the outer surface of the flake. Because the oxidation is controlled so that the selective oxidation produces a thin outer shell, the particle has good reflectance and the metallic core of the particle is unaffected by the oxidizing treatment. Although the techniques of the present invention are effective for producing a reflective surface on aluminum-containing iron alloys while the core particles can be either magnetically soft or hard, the techniques can be used to produce a reflective surface that is corrosion and oxidation resistant on any aluminum containing alloy. Apparatus that facilitates the controlled oxidation is also set forth.

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First Claim