CEMENTATION AS A METHOD OF OBSERVING DEFECTS IN PVD COATINGS

The cementation test as previously used to investigate defects in sing le metal nitride PVD coatings has been extended to the study of the ne w 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 an d CrN coatings examined. A detailed cementation mechanism is given whi ch explains the formation of copper deposits on the surface of PVD coa tings rather than being confined to within the pores and defects in co atings. It is suggested that cementation tests might be used to advant age as a quality control tool to give an early indication of an above average incidence of defects within a batch of recently coated compone nts. (C) 1997 Elsevier Science Ltd.