Industrial PVD coatings for improving corrosion protection of components for polymeric injection moulding

In industrial settings, the problem of degradation of metallic moulds for polymeric material processing is a serious problem. The presence of aggressive additives in polymeric formulations can cause corrosive damage on metal surfaces and also corrosion on moulds coated with hard materials, such as physical vapour deposited (PVD) coatings. Successive corrosion events can ultimately lead to the failure of the mould. A careful microstructural characterisation of the coatings was obtained on steel substrates and copper alloys, typical moulds alloys, and porosity was estimated by of electrochemical techniques. Corrosion resistance was evaluated using electrochemical techniques during electrolyte immersion and through exposure to aggressive vapours. The final aim of the experiments was to obtain information regarding proper coating choice for specific applications. Experimental approaches for evaluating protective properties and the porosity of hard coatings are discussed for the future. © 2007 Institute of Materials, Minerals and Mining.