Hardness measurement of CVD diamond coatings on SiC substrates

Hardness of CVD diamond coatings was determined by CSM™ nanohardness tester (NHT) and Vickers microhardness tester. Nanoindentation measurements were performed with loads from 50 to 300 mN and measured hardness and elastic modulus values were about 105 and 1147 GPa, respectively. These values were compared with the values found from the Vickers microhardness tester. This work justifies the use of the nanoindentation technique over conventional microhardness tests for reliable measurement of hardness of chemical vapour deposited (CVD) diamond coatings as microhardness testing resulted in localised damage precluding accurate measurement.