Tribological properties of ultrananocrystalline diamond nanowire thin film: influence of sliding ball counterbodies

Ultrananocrystalline Diamond Nanowire (UNCD NW) thin film was deposited on mirror polished silicon substrate (100) using Microwave Plasma Enhanced Chemical Vapor Deposition (MPECVD) System with optimized deposition parameters in CH₄ (6%)/N₂ plasma media. The film exhibited wire like morphology with randomly oriented and homogeneously distributed ultranano diamond grains separated by an interphase boundary of graphitic and amorphous carbon (a-C) phases. Micro-tribological studies of film were carried out against various counterbody balls of Al₂O₃, SiC and Steel in ambient atmospheric conditions. Initially, the friction coefficient was found to be high for UNCD NW/SiC and UNCD NW/Steel sliding pairs which gradually decreased to low value. While, in UNCD NW/ 69 Al₂O₃ sliding combination, the ultralow value of friction coefficient was maintained throughout the sliding process. Highly wear resistant properties of the film were observed in UNCD NW/SiC and UNCD NW/Steel pairs. While in UNCD NW/Al₂O₃ case, ball counterbody showed negligible wear dimension. (author)