The dependence of the structural and morphological properties of nanocrystalline diamond films grown by hot filament chemical vapor deposition on the substrate temperature was studied. Friction coefficients of these films were measured and found to vary from high to ultra low, depending on the chemical nature of the films i.e., sp2 and sp3 phase fractions. For all films, the friction coefficient was found to decrease with increase in sp2/sp3 phase fraction. The wear rate follows the trend of the friction coefficient and was likewise found to depend on the structural and morphological properties of the films. For all the films, the friction coefficient is found to decrease with normal load which is ascribed to sliding induced surface amorphization/graphitization.
