Cermet of tungsten carbide grains held in a cobalt matrix, usually 12 or 17 percent cobalt, with chromium added (WC-10Co-4Cr) where corrosion resistance matters. Sprayed by HVOF or HVAF it reaches about 1,000 to 1,300 HV with very low porosity, resisting abrasion and sliding wear on pump parts, valves, rolls and landing gear. Too hot a process decarburizes the WC to brittle W2C and metallic tungsten, so cooler, faster processes are preferred.
Ball valve gets WC-Co on the ball and seats, lap them together after grind.
WC-Co loses its edge above roughly 500 °C as the carbide oxidizes, so hot parts get chromium carbide instead.
Also heard as
- tungsten carbide cobalt
- WC-CoCr
- WC-12Co
- WC-17Co
Do not mix it up with
- Chromium carbide: WC-Co is harder and more wear resistant at moderate temperature, while chromium carbide keeps working at much higher temperatures.
Related terms
Carbide
Shop shorthand for a carbide coating, usually tungsten carbide, as in putting carbide on a part.
HVOF
High-velocity oxygen fuel: burning fuel and oxygen under pressure to fire powder at supersonic speed.
Hard chrome replacement
Using HVOF carbide coatings in place of electroplated hard chrome on rods, pins and landing gear.
Chromium carbide
Cr3C2 carbide held in a nickel-chromium binder, a wear coating that keeps working at high temperatures.