Measurements of the coefficients of friction of different lubricants during impact under high pressure and shear

Abstract

For a comprehensive set of lubricants the friction coefficients were determined under very high pressures and shear rates by means of a ball impact experiment. Measurements of the limiting shear stresses were obtained for a large range of pressures, from about 2 to 4 GPa, as typically encountered in elastohydrodynamic contacts. It was shown that under these conditions the limiting shear stresses increased less than proportionally with the pressure; i.e. the coefficients of friction were decreasing functions of the pressures. The results were compared with previously reported values from the literature and in general good agreement was obtained.