Application of Diamond and Diamond-Like Carbon Films as Lubricating Coatings

摘要

Recent work on the friction and wear properties of microwave- plasma - deposited fine grain diamond films, ion-beam-deposited diamond-like carbon (DLC) films, and rapid-thermal- annealed DLC films is reviewed. The fine grain diamond films contained about 2.5 atomic hydrogen. The diamond grain sizes ranged from 20 to 100 nm with the preferred orientation growth of (110). The average surface roughness (R(sub rms)), of the diamond films was 15 nm. The DLC films contained about 30 atomic hydrogen. The hydrogen content of the rapid-thermal- annealed DLC films ranged from 30 to 5 atomic with the annealing temperature range of 350 to 1000'C. Reciprocating sliding friction experiments were conducted on the diamond, DLC, and rapid-thermal-annealed DLC films in contact with silicon nitride pins both in humid air and in dry nitrogen. Reference experiments for the friction and wear were also conducted on silicon nitride flats in contact with silicon nitride pins. The coefficients of friction for the diamond films were found to be 0. 1 1 and 0.03 in humid air and in dry nitrogen environments, respectively. The friction coefficients of the DLC films were 0.15 and 0.01 in humid air and in dry nitrogen environments, respectively. The coefficients of friction for the diamond and DLC were considerably lower than those for the uncoated silicon nitride flats. Both diamond and DLC films had low wear factors both in humid air and in dry nitrogen environments. Thus, diamond and DLC films can be effectively used as solid lubricating coatings for ceramics such as silicon nitride. The effect of rapid-thermal-annealing on the friction for DLC films was minimal both in humid air and in dry nitrogen environments. The wear factors of the DLC films, however, were strongly dependent on the annealing temperature and moisture in the environments.