An experimental study of the nano-scratch behaviour of poly(methyl methacrylate)

An experimental study of poly(methyl methacrylate) (PMMA) is described with the aim of investigating the potential for the formation of wear particles by the interaction of multiple scratches under plastic ploughing conditions. The work was carried out using a nano-indenter fitted with a Berkovich probe. It was found that orthogonally intersecting scratches produced lumpy protuberances which could act as a precursor for wear particles. However, parallel scratches in close proximity resulted in a self-protective mechanism due to the load carrying capacity of the strain hardened pile-up from neighbouring scratches.