Conversion coatings is a generic term used to refer to a coating produced by a chemical or electrochemical treatment of a metallic surface that gives a superficial layer containing a compound of the metal. For ease of explanation we are going to further sub-divide this category into steel conversion coatings, chromate conversion coatings, and anodize which is covered elsewhere.

Steel Conversion Coatings (Black Oxide & Phosphate)

Black OxideBlack Oxide:

Black Oxide is a conversion coating formed by a chemical reaction with the iron in the metal to form an integral protective surface. (Contrasted to an applied coating which bonds to the metal but does not react chemically.) A black oxide conversion coating is applied to ferrous alloys when oxidizing salts react with the iron to form magnetite (Fe3O4), the black oxide of iron. Though standard Black Oxide is set up for steel, it can be done on other substrates including stainless steel, copper, and brass among others.

Typically black oxide has a post dip of either oil or wax to improve the corrosion protection of the finish. Black oxide offers a nice, matte black appearance at a low cost.

Black Oxide Features:

Corrosion Resistance (when oiled/waxed)
Appearance
Cost Competitive
Dimensional Stability

Substrate : aluminum
Production method : large series, medium series, small series
Certifications : ISO 9001, ISO 14001
Applications : military