HARDNESS AND ELASTIC-MODULUS OF DIAMOND AND DIAMOND-LIKE CARBON-FILMS

The hardness H and Young's modulus E, of a polycrystalline diamond film and five diamond-like carbon (DLC) films were determined from force-displacement curves obtained using an ultralow load microhardness instrument (UMIS-2000). The response of the diamond film shows nearly complete elastic behaviour, and its hardness (80-100 GPa) and modulus (500-533 GPa) are comparable with those of natural (001) diamond (H = 56-102 GPa; E = 1050 GPa). The DLC films, prepared by low energy ion-assisted unbalanced magnetron sputtering, differ in their sp3-to-sp2 bonding ratio and macroscopic properties. The force-displacement curves show substantial elastic recovery. Individual films have hardness and elastic modulus in the range 12-30 GPa and 62-213 GPa respectively. Increasing hardness and modulus correlate with the increasing ion energy per condensing carbon atom from 29 to 67 eV, sp3-to-sp2 bonding ratio from 3 to 6, and optical energy gap from 1.2 to 1.6 eV.