Scratch Test for Coating/Substrate Systems – A Literature Review

The scratch test consists of a diamond stylus moving over the surface of a sample under a normal force which is increased either stepwise or continuously until a critical normal force is reached, at which point a well-defined coating failure occurs. This force is then taken as a measure of adhesion. In this paper, a literature review on scratch testing applied to coating/substrate systems is provided. Tribological contact mechanics, failure modes, factors affecting the scratch test results, adhesion measurements, friction effects as well as finite element modelling of the scratch test are discussed.