BxNyCz:H films were prepared in a capacitively coupled r.f. PACVD reactor at deposition temperatures < 200°C starting from CH4-N2-B2H6 (10% diluted in H2 or He) gas mixtures. The composition (B, N, C, H) was analyzed using electron probe microanalysis and elastic recoil detection. Tribological film properties (wear and friction) were investigated by ball-on-disc testing under dry and humid N2 atmospheres. Hardness and Young's modulus were determined by depth-sensing indentation measurements. It will be shown that among the wide range of compositions investigated, the pure amorphous carbon films (a-C:H) remain unsurpassed with respect to wear and friction behavior. The addition of B and/or N to a-C:H films reduced their hardness and wear resistance, while the friction coefficient remained low (0.2) and increased for BN-rich films (>0.5). As an-exception, a striking similarity was found between a-B:H and a-C:H films with respect to their mechanical properties (hardness, Young's modulus). Nevertheless these a-B:H films also showed a much lower wear resistance in ball-on-disc tests due to different friction mechanisms related to the formation of transfer layers. Ball-on-disc tests performed on BN coatings on glass substrates show an important influence of material transfer from the steel counterbody to the coating, resulting in a fluctuating friction coefficient between 0.1 and 1. These mechanical, wear and friction data are correlated with the coatings microstructural properties as determined from infrared spectroscopy, Raman spectroscopy and glancing angle X-ray diffraction.
|Tijdschrift||Diamond Films and Technology|
|Nummer van het tijdschrift||3|
|Status||Gepubliceerd - 1 dec 1997|