Adaptive Protocol for Robust Estimates of Coatings Properties by Nanoindentation

摘要

The determination of the elastic modulus and hardness of a wide range of coating systems has been studied recently in the EC project INDICOAT. This paper describes a protocol for determining the coating properties, which has been developed and tested in that project. The procedure contains simple to implement strategies to evaluate the response of the coating and design a suitable series of indentation experiments that enable a reasonable estimation of 'coating-only' properties. The protocol directs how the experimental design adapts the experimental parameters to each sample. An adaptive protocol is essential to cope adequately with the different indentation responses. Indentation response depends, for example, on coating thickness and the relative properties of coating and substrate and creep response. The protocol also has to adapt itself so that it can reliably target the range of indentation depth with respect to the coating thickness necessary to obtain the coating properties from the composite indentation response. Results presented show that the parameters and approach for measurement of hard coatings are very different to those required for soft or ductile coatings. The systems studied are DLC on tool steel, Au on Ni, aluminium oxide on Ni and aluminium on optical glass (BK7).