Conversions coatings for metal are surface treatments that offer wear resistance, corrosion resistance and decoration as well as a receptive layer for paints, adhesives, etc. These coatings are achieved through the use of chemical or electrochemical processes which convert the metal surface into the finish that is specified, the most common processes are chromate, phosphate and oxide. Oxide finishes are particularly used for decorative purposes and can include black oxide and gun bluing. Chromate and phosphate offer specialized finishes which are wear resistant and serve as conductive elements as well as paint primers.
Metal parts are often conversion coated to improve the appearance or characteristics of the metal surface. A conversion coating is a widely used example of this type of process and can be successfully used with various metals including steel, aluminum and copper as well as brass.
Oxide conversion is one of the three common variants, these Coatings For Metal normally are used on steel although they can be used on copper and brass as well but this is not as common. This type of coating is achieved by exposing the substrate surface to various chemicals which react with components in the alloy to form the oxide layer. Oxide conversions make the metal resistant to corrosion and offer dimensional stability and decorative qualities. This type of coating is normally found on volume produced components such as firearms, tools and various fasteners.
Another common conversion coating is a phosphate treatment. This type of treatment results in a matter grey color and involves phosphate spray or immersion during which a crystalline structure is grown on the surface of the metal. Iron phosphate is often used as a metal primer prior to painting. Layers of zinc are used on domestic appliance and automobile body pressings, it is also common to use zinc layers on cold forming dies which extend their service life. Manganese phosphate layers are used where the need is to have a friction reducer on high stress parts such as cam shafts, pistons and gears.
Chromate treatment is the third type of conversion coatings for metal. This finish is yellow or clear and is often used where corrosion resistance is needed; this coating also acts as an excellent conductor of electricity.
