Mechanical properties of different types of diamond

The mechanical properties of different types of diamond (synthetic diamonds with different nitrogen impurity concentrations 0.3 and 200 ppm) have been investigated by sclerometry hardness and wear resistance measurements. Dia mond (111) and (100) faces in the [100] and [110] directions were tested. I t was found the synthetic diamond with nitrogen impurity concentration of 0 .3 ppm exceeds other diamond types with respect to hardness and wear resist ance, and reveals anisotropy of the mechanical properties, different from o ther diamond types. The hardness measured on the (111) face for synthetic d iamond was 175 +/- 5 GPa for 0.3 ppm of nitrogen impurities and 151 +/- 5 G Pa for 200 ppm of nitrogen impurities. The hardness measurements were perfo rmed using an ultrahard fullerite indenter exceeding diamond in hardness an d the diamond faces were deformed plastically under scratching conditions. (C) 1999 Elsevier Science S.A. All rights reserved.