Black Oxide Coatings
General Details and Specification of black oxide finishes
Black Oxide, Blackening, Oxidizing, Oxiding, Black Passivating, Gun Bluing . . . these terms all refer to the process of forming a black iron oxide on the surface of metals. Mostly a decorative coating. Only very limited corrosion protection under mild corrosion conditions. Black oxide coatings should normally be given a supplementary treatment (i.e. oil displacement per MiL-C-16173 Grade 3 or protective treatments of MiL-C-16173).
Benefits of black oxide
- Corrosion Protection
- Produces a lubricating film for smoother running of parts
- Dimensional Stability
- Black oxide finishing produces an attractive, decorative black finish
- Black oxide finish reduces glare and eye fatigue
- Free of Noxious Fumes When Welded
| Specs | Thickness | Comments |
|---|---|---|
| MIL-DTL-13924D | No dimensional change | For moving parts that cannot tolerate the dimensional change of a more corrosion resistant finish. |
| Class I | No dimensional change | Alkaline oxidizing process (for wrought iron, cast and malleable irons, plain carbon, and low alloy steels. |
| Class 4 | No dimensional change | Alkaline oxidizing process (for other corrosion resistant steel alloys). |
Chemical Finish: black
A uniforrn black corrosion retardant for copper. Coating has no abrasion resistance.
| Specs | Thickness | Comments |
|---|---|---|
| M1L-F-495E | No dimensional change | Used as a base for lacquer, light oil, or wax. For decorative, optical, and corrosion retardant applications. |