Tribological fundamentals of polycrystalline diamond films

A decade's worth of SEM-tribometric work on polycrystalline diamond films is reviewed. Diamond-coated Si and SiC specimens have been tested under oscillatory sliding, at temperatures from room ambient to 1000 degrees C in (a) similar to 1.33x10(-3) Pa (similar to 1 x 10(-5) Torr) vacuum, (b) 13-39 Pa (0.1-0.3 Torr) partial pressures of hydrogen and (c) 26 Pa (0.2 Torr) partial pressure of oxygen. The temperature- and atmosphere-controlled tribological behavior of the films is interpreted by the environment-dependent values and trends of the average coefficient of friction. Accurate interpretation of the results is assisted by similar friction and wear data on various silicon crystallinities, complemented by applicable thermal desorption, surface chemical and tribometric data taken from the literature. (C) 1999 Elsevier Science S.A. All rights reserved.