Zn flake≤ 300 °C
Zinc flake (Geomet / Dacromet)
Zinc and aluminium flakes in an inorganic binder, cured in an oven rather than plated. Because no electrolysis is involved there is no hydrogen to embrittle the steel — which is why it is the coating of choice for class 10.9 and 12.9.
Specification
| Standards | ISO 10683 · ASTM F1136 · Geomet 321 / 500 · Dacromet 320 |
|---|---|
| Thickness | 8 – 12 µm |
| Colour | Silver-grey; black available with a topcoat |
| Maximum temperature | 300 °C |
| Salt spray, ASTM B117 | 480 – 1 000 h tuy so lop |
| Friction | µ ≈ 0,09 – 0,14 khi co lop boi tron tich hop — on dinh, phu hop xiet bang luc |
What it does well
- No hydrogen embrittlement risk at all — the decisive advantage on high-strength fasteners
- Very thin, so standard thread fits are preserved
- Integrated lubricant gives a controlled, specified friction coefficient
- Holds up to 300 °C, well beyond what zinc plating tolerates
Where it falls short
- Not sacrificial in the same way as thick galvanizing — deep mechanical damage exposes bare steel
- Requires an oven cure, so it is a batch process with a longer lead time
- More expensive than zinc plating
Specify it when
Class 10.9 and 12.9 fasteners, wind turbine bolting, automotive and any application where hydrogen embrittlement is a stated concern.
Grades we apply it to
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