A fractional coverage model for gas–surface interaction in reciprocating sliding contacts

A model of fractional coverage in reciprocating sliding contact is developed. The sliding velocity profiles, the contact pressure distribution, the lengths of the slider or wear-track, and the periods of dwell where the slider is held stationary at the turn around locations are all variables. The model is evaluated for the condition of a constant fully reversing sliding speed with a uniform contact pressure and dwell. Plots are presented for surface area fractional coverage as a function of position illustrating the effects of individually varying vapor pressure, velocity, load, and dwell. The prediction of a steady state friction coefficient dependence on position is discussed, as well as the locations of maximum and minimum friction coefficient. The model predicts coverage to be enhanced by decreasing loads, decreasing sliding speeds, increasing gas pressures, and increasing periods of dwell.