Black oxide plating (or black oxide coating or blackening) can increase the useful life of your industrial tools and machinery, as it improves corrosion resistance of the base surface. The black oxide plating process also provides better dimensional stability and appearance to the component surface than other plating processes. Understanding black oxide plating key terms will help you make smarter choices. This guide covers some of the common terms that you will hear about from plating service providers, including surface preparation, conversion coatings and Mohs scale.
For efficient adhesion of coating to the component material, you will need to clean the component surface before applying any coating. There are several techniques of surface preparation, such as sand blasting, shot blasting and abrasive blasting.
Conversion coating is an inorganic pre-treatment for a metal component that improves adhesion and corrosion resistance of the metal surface.
Black oxide plating
Black oxide plating is a conversion coating that is formed by a chemical reaction with iron in the metal to form an integral protective surface. You can apply black oxide coating to various metals and alloys, including steel, copper and brass.
Hot black oxide plating
Generally, plating service providers perform the black oxide process at high temperature and hence, the process is known as hot black oxide plating.
Cold black oxide plating
As the name indicates, cold black oxide plating (or room temperature black oxide plating) does not require heating of the metal components. This process is applicable for batch production and touch-up work for larger parts. However, this process does not always meet standard specifications.
Mostly, metal-finishing service providers specify the surface hardness of black oxide coating by using the Mohs scale. You will need to specify the surface hardness for your components as per the application requirements.
MIL spec plating
Metal-finishing service providers specify their metal-plating capabilities in terms of different specifications. The U.S. Army Research Laboratory develops and publishes specifications known as MIL spec (or military specifications).