Study of mechanical properties of CVD diamond on SiC substrates

This work justifies the use of the nanoindentation technique over conventional microhardness tests for reliable measurement of the mechanical properties of chemical vapour deposited (CVD) diamond coatings, as microhardness testing resulted in localised damage precluding accurate measurement. Mechanical properties namely hardness and Young's modulus, of CVD diamond were determined by CSM™ nanohardness tester (NHT) and conventional Vickers micro hardness tester. Nanoindentation measurements were performed with loads from 50 mN to 300 mN and measured hardness and elastic modulus values were approximately 105 GPa and 1147 GPa, respectively. These values were compared with the values found from the Vickers microhardness tester. Bonding properties of the coatings were analysed by micro Raman spectroscopy and topography was analysed by AFM.