Black Oxide has unique properties offering an ideal finish for the metal manufacturing industry
What is Black Oxide
Black oxide is the 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 (Fe304), the black oxide of iron.
Black oxide coatings are offered under a variety of trade names including Black Magic, Black Penetrate, Black Passivation, Gun Bluing and others. While some can be applied at room temperature, most are applied at elevated temperatures. All the benefits of black oxide are only available from the "hot" oxidizing process.
Where is it used
Black oxide conversion coatings are widely used in the machine tool, automotive, appliance and general metal forming industries. Screw machine parts, forgings and stampings are commonly black oxide coated.
Why chemically blacken?
1.
To eliminate dimensional change. Black oxiding changes the metals surface so there is essentially no surface build up or distortion. Excellent for gauges, bolts, cams, screws, and precision machine surfaces.
2.
For a decorative finish. Black oxiding enhances the appearance of many items.
3.
To improve corrosion resistance. Black oxided metal absorbs final sealants and rust preventatives, keeping them in contact with the metal itself longer then if the preventative was applied to the bare metal. You can obtain twice the corrosion resistance of non-black oxided metals. Along with a post treatment, corrosion resistance of 72 to 144 salt spray hours is possible.
4.
For improved abrasion resistance. Black oxiding lets the outer lubricating layer be sacrificed during contact and abrasion. Excellent for breaking in tools.
5.
For improved adhesion qualities. Because Black oxiding changes the surface properties, the adhesion qualities of metal are greatly enhanced. Paint and other finishes take a better hold and last longer.
6.
Conductivity –Black oxided parts experience no more than a 1% reduction in conductivity, making it a suitable treatment for electrical parts.
7.
No Embrittlement – Unlike painted or plated parts which are oftentimes acid etched, no hydrogen embrittlement accompanies black oxiding.
