Effects of material pair properties on the frictional behavior of metals

The objective of this work was to investigate the validity of the adhesion theory and the mechanical interaction view point in describing the friction al behavior of metals. Specifically, experimental work was conducted to inv estigate the relative importance of the material compatibility and hardness ratio on the friction and wear behavior of various metals in dry sliding c ondition in ordinary laboratory environment. Initial and steady state frict ion coefficients were measured using both pin-on-disk and pin-on-reciprocat ing testers for various metal pairs, which were strategically selected base d on their compatibility and hardness ratio. The wear characteristics were also observed following the experiments. The experimental results showed th at material compatibility had no significant correlation with either initia l or steady state friction coefficient. As for the hardness ratio, material pairs with very large differences in initial hardness values resulted in h igh initial friction coefficient. Overall, it was observed that factors suc h as sliding motion, whether unidirectional or bi-directional, and wear par ticle dynamics were found to be more critical on frictional interaction tha n either material compatibility or initial hardness ratio. Furthermore, amo ng several material properties analyzed, initial friction coefficient had t he highest correlation with shear modulus while the steady state friction c oefficient had the highest correlation with hardness. (C) 1999 Published by Elsevier Science S.A. All rights reserved.