Reproducibility of friction and wear results in ball-on-disc unidirectional sliding tests of TiN-alumina pairings

In a European research programme focused on the development and validation of test methods for thin hard coatings, friction and wear characteristics of TIN coatings were investigated. Ball-on-disc sliding tests were performed in ambient air of 50% RH at various applied loads under a fixed sliding speed. The coefficient of friction was measured on-line whereas the worn-off volume was determined by laser stylus profilometry and mass loss measurements. The two wear loss methods were compared. It was confirmed that the profilometry measured wear volume is linearly dependent on the total dissipated energy as long as the coating is not worn through. From this study, the effect of normal load on the friction and wear behaviour of TIN coatings and the reproducibility of the tribotests are discussed. (C) 1997 Elsevier Science S.A.