ANTIWEAR MATERIAL CRITERIA

Stéphane Neuville (France)

Received January 10, 2008

Abstract

Many reasons justify the availability of a universal and accurate antiwear material criterion. Not only for the selection of an appropriate coating material, but also in order to allow comparisons of coating/substrate systems when other aspects have to be considered such as adhesion, surface rugosity, thermal and chemical stability, stress, etc., and especially when antiwear properties have to be associated to other functions (optical, electrical, etc.). Antiwear properties are known not only to depend on hardness. A simple theoretic analysis is presented involving atomic solid state considerations on hardness and the particle detachment mechanisms during the wear process, which suggests that the H/E criterion has to be implemented with other parameters influencing the stress and strain in the coating/substrate system. Therefore, we suggest using instead of the H/E ratio the H/f.E formula as a preliminary selection rule, which appears to be in good agreement with many antiwear results achieved with coatings of different types and especially polished diamond and low friction high hardness ta-C providing in many cases the highest antiwear results.

Keywords and phrases: FEM, Skew laminate, cutout, interlaminar stresses.