Vickers or Knoop indentation with small loads, commonly 300 grams (HV0.3), placed in the middle of the coating thickness on a mount, usually averaged over about ten readings. Coatings are too thin and too porous for normal Rockwell testing, so microhardness is the standard check. Typical values are around 1,000 to 1,300 HV for HVOF tungsten carbide and lower for chromium carbide and metallic coatings.
Microhardness averaged 1,150 HV0.3 on the carbide coupon, scatter's tight, good to go.
Also heard as
- HV0.3
- Vickers
- Knoop
- DPH
Related terms
Mount
A polished cross section of a coated coupon set in resin, used to check structure under the microscope.
WC-Co
Tungsten carbide in a cobalt binder, the most common wear-resistant thermal spray coating.
Porosity
The fraction of a coating's volume made of voids between and within splats, usually reported in percent.