A thin silver-gray coating applied by dip-spin or spray and cured in an oven, built from overlapping zinc and aluminum flakes in an inorganic binder. Since no acid cleaning or electroplating is involved, it carries no risk of process hydrogen embrittlement, which makes it the default on high-strength automotive and wind turbine bolts. A coating of roughly 6 to 15 microns gives hundreds to over a thousand hours of salt spray, and lubricated topcoats hold friction in a controlled range.
Switch the 10.9 suspension bolts to zinc flake, we're not electroplating anything that hard.
Also heard as
- zinc flake coating
- Geomet
- Dacromet
Related terms
Zinc plating
An electroplated zinc layer, usually with a clear, blue or yellow passivate, the cheapest common fastener finish.
Hydrogen embrittlement
Delayed brittle cracking of hard steel fasteners caused by hydrogen absorbed from plating, cleaning or corrosion.
Nut factor
The empirical constant K in T = KDF that lumps all the friction and geometry between torque and tension.
HDG
Hot-dip galvanized: coated by dipping in molten zinc, leaving a thick, rugged layer for outdoor steel.