Surface Coatings

Steel Conversion Coatings (Black Oxide & Phosphate)

Black 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.

Manganese Phosphate Coating

Metal Coatings offers black manganese phosphate coatings and dark gray manganese phosphate coatings (Type M) used for corrosion protection, anti-galling and lubricity. Of the numerous phosphate coating available, manganese phosphate coatings are the hardest, while providing unbeatable corrosion and abrasion protection. In comparison to zinc phosphate coatings, manganese phosphate coatings offer continued wear protection after the breaking in of components that are subject to wearing. These coatings are applied only by immersion. Uses for manganese phosphate applications include the production of bearings, bushings, fasteners, and other common industrial products. Manganese phosphate coating is especially useful in projects that require sliding of parts, such as automotive engines and transmission systems.