Cementation as a method of observing defects in PVD coatings

The cementation test as previously used to investigate defects in single metal nitride PVD coatings has been extended to the study of the new generation of mixed nitride coatings by its application to the study of defects in TiAlN coatings. Copper cementation tests carried out in a solution containing 0.1 g l(-1) of copper at pH 1.1 showed that the incidence of defects in TiAlN lay in between that found in the TiN and CrN coatings examined. A detailed cementation mechanism is given which explains the formation of copper deposits on the surface of PVD coatings rather than being confined to within the pores and defects in coatings. It is suggested that cementation tests might be used to advantage as a quality control tool to give an early indication of an above average incidence of defects within a batch of recently coated components. (C) 1997 Elsevier Science Ltd.