TRACTION BEHAVIOR AND PHYSICAL-PROPERTIES OF POWDER GRAPHITE LUBRICANTS COMPACTED TO HERTZIAN PRESSURE LEVELS

This paper gives a method for predicting traction coefficients of grap hite powder lubricants. The analysis is based on the assumption, that unconsolidated powder lubricants behave as elastic solids when compres sed to Hertzian pressure levels in rolling contact regions. This assum ption is supported by the classic work of P. W. Bridgman who studied t he effects of extreme pressure on physical properties of several chemi cal substances, including graphite. The paper also gives bulk modulus data for graphite powder compressed up to 690 MPa (100,000 psi) and sh ows how this property can be used to predict the film thickness of gra phite powder in Hertzian contact.