Black oxide≤ 250 °C
Black oxide
A one-micron black iron oxide conversion layer. It changes the colour and nothing else — treat it as a cosmetic and anti-glare finish that needs oil to resist even light humidity.
Specification
| Standards | MIL-DTL-13924 · ASTM D769 · AMS 2485 |
|---|---|
| Thickness | ~ 1 µm |
| Colour | Deep black, slightly satin |
| Maximum temperature | 250 °C |
| Salt spray, ASTM B117 | < 24 h — chi khi con lop dau bao ve |
| Friction | µ ≈ 0,15 – 0,20 khi co dau |
What it does well
- Adds no measurable thickness — thread fit is completely unchanged
- Non-reflective, which matters on instrument and optical assemblies
- Very low cost
Where it falls short
- Essentially no corrosion resistance of its own
- Needs re-oiling to stay black in storage
- Wrong choice for any pressure-retaining outdoor joint
Specify it when
Indoor machinery, tooling, jigs and fixtures where appearance matters more than corrosion life.
Grades we apply it to
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