Black oxide or blackening is a conversion coating for ferrous materials, copper and copper based alloys, zinc, powdered metals and silver solder. It is used to add mild corrosion resistance and for appearance. One of its advantages over other coatings is its minimal buildup.
The result of the process is an attractive but very thin and marginally corrosion-resistant, dark black iron oxide finish. This black finish is familiar as it is seen in gears and sprockets, some brands of spark plugs, and socket wrenches and other tools. It is also used on firearm components, such as rifle barrels.
Machining and Fabrication
Plating is a surface covering in which a metal is deposited on a conductive surface. Plating has been done for hundreds of years, but it is also critical for modern technology. Plating is used to decorate objects, for corrosion inhibition, to improve solderability, to harden, to improve wearability, to reduce friction, to improve paint adhesion, to alter conductivity, for radiation shielding, and for other purposes.
Different metals provide different colors and finishes. Common metals used in plating are Gold, Silver, Chrome, Zinc, and Tin.
Anodizing is an electrochemical process that converts the metal surface into a decorative, durable, corrosion-resistant, anodic oxide finish. Aluminum is ideally suited to anodizing, although other nonferrous metals, such as magnesium and titanium, also can be anodized.
Anodizing is accomplished by immersing the aluminum into an acid electrolyte bath and passing an electric current through the medium. A cathode is mounted to the inside of the anodizing tank; the aluminum acts as an anode, so that oxygen ions are released from the electrolyte to combine with the aluminum atoms at the surface of the part being anodized. Anodizing is, therefore, a matter of highly controlled oxidation—the enhancement of a naturally occurring phenomenon.
Full Service Manufacturing
Powder coating is a type of coating that is applied as a free-flowing, dry powder. The main difference between a conventional liquid paint and a powder coating is that the powder coating does not require a solvent to keep the binder and filler parts in a liquid suspension form. It is usually used to create a hard finish that is tougher than conventional paint.
The coating is typically applied electrostatically and is then cured under heat to allow it to flow and form a "skin". The powder may be a thermoplastic or a thermoset polymer. Powder coating is mainly used for coating of metals, such as "whiteware", aluminium extrusions, and automobile and bicycle parts.
Finishing and Plating