Abstract
Nakamori et al. found experimentally that the friction between a partly polished diamond coating and a metal surface was drastically reduced to zero as relative speed was increased [Diamond Relat. Mater., 14, (2005), 2122]. It seems that diamond coating took off the counter surface because sliding was noiseless in their experiment. This phenomenon shows the possibility of innovative new gas lubrication system. The mechanism of generation of the lift force occurred in their experiment was unsolved although the lift force is necessary for gas lubrication. The surface roughness of the partly polished diamond-coated substrates is from 0.28μm to 0.57μm in their experiment. In the present paper, we clarify the mechanism that causes the lift force when the sliding surface has the micro-/nanoscale roughness by performing numerical simulations of micro-/nanoscale gas flows between two sliding surfaces. Since micro-/nanoscale gas flows between two sliding surfaces cannot be treated as a continuum, we use the direct simulation Monte Carlo (DSMC) method.
