ANODIZING

Anodizing entails the immersion of an aluminum part in an electrolyte where an electric current is passed through the part. The surface is converted to aluminum oxide - one of the hardest substances known.

Proper formation of aluminum oxide coatings provides aluminum with a natural decorative appearance and increased resistance to corrosion and abrasion. In addition, it serves as a base for color absorption to create decorative finishes

During sulfuric anodizing, no metallics are involved other than aluminum. Unlike electro-deposited metallic plating, where plating builds up by depositing on a base metal, an anodic coating penetrates and grows on the base metal by converting aluminum to aluminum oxide. The ratio of growth/penetration for anodic coatings is typically 50/50*. (*For critical applications, please consult with your DFI Metal Finishing sales engineer).

Proper formation of aluminum oxide coatings provides aluminum with a natural decorative appearance and increased resistance to corrosion and abrasion. Normally between .0001" to .001" thick, sulfuric anodizing lends itself readily to clear and color work, as the coating is more transparent than other types of anodizing. In addition, it serves as a base for color absorption to create decorative finishes. Dyes can be deposited into the pores of the anodized layer and then sealed. The result is a highly desirable, rich, intense, permanent color finish.

The final treatment of clear or dyed anodized aluminum is sealing to close the pores of the aluminum oxide and render the coating non-absorptive. Sealing is accomplished by immersion in deionized water containing either nickel acetate, nickel fluoride, sodium dichromate or near boiling ionized water (water chemically distilled to a high degree of purity).

Colors
For our type II anodize coatings we, offer a wide range of colors from red, blue, orange, green, architectural brown, grey, pewter, wheat, umber black and clear.

Download Mil-A-8625

Download PDF Technical Bulletin.