Black Oxide Coating Thickness

Dipping a metal part into a heated alkaline liquid for a specific period of time triggers the chemical process that forms magnetite on the part s surface.

Black oxide coating thickness.

Though standard black oxide is set up for steel it can be done on other substrates including stainless steel copper and brass among others. The point of the black oxide process is to create magnetite fe3o4 an alloy of iron and oxygen molecules on the surface of the metal. One of its advantages over other coatings is. A black oxide conversion coating is applied to ferrous alloys when oxidizing salts react with the iron to form magnetite fe 3 o 4 the black oxide of iron.

It is used to add mild corrosion resistance for appearance and to minimize light reflection. Bluing is a passivation process in which steel is partially protected against rust and is named after the blue black appearance of the resulting protective finish true gun bluing is an electrochemical conversion coating resulting from an oxidizing chemical reaction with iron on the surface selectively forming magnetite fe 3 o 4 the black oxide of iron. Black oxide or blackening is a conversion coating for ferrous materials stainless steel copper and copper based alloys zinc powdered metals and silver solder. The reaction between the iron of the ferrous alloy and the hot oxide bath produces a magnitite fe3 o4 on the actual surface of the part.

Black oxide is a conversion coating formed by a chemical reaction produced when parts are immersed in the alkaline aqueous salt solution operated at approximately 285 degrees f. An adherent black oxide coating on a bearing is reported to improve the reliability and performance of bearings especially in wind turbines 3 16 and hence reduced downtime and maintenance costs. I would like to consider using black oxide but need to know more about the capabilities. To achieve maximal corrosion resistance the black oxide must be impregnated with oil or wax.

How black oxide coating works. A typical thickness of the black oxide layer is about one to two micrometers 2 3 10 13. A discussion started in 1999 but continuing through 2018. Black oxide penetrates the steel 5 10 thousandths and adds to the part thickness by only 5 10 thousandths providing a hardness of 5 on the mohes scale.

Strong adhesion between the coating and the substrate. Black oxide coating thickness. Mostly a decorative coating. Only very limited corrosion protection under mild corrosion conditions.

For moving parts which cannot tolerate the dimensional change of a more corrosion resistant finish. Black oxide coating mil c 13924 a uniform black coating for ferrous metals. Thickness of black oxide coating does not exceed 3 10 5 inch 0 75 µm half of which is added to the part dimension and the second half penetrates into the part depth. Black oxide coating does not peel from the surface.