THE EFFECTS OF DEPOSITION TEMPERATURE AND INTERLAYER THICKNESS ON THE ADHESION OF ION-ASSISTED TITANIUM NITRIDE FILMS PRODUCED WITH YTTRIUM METAL INTERLAYERS

The use of thin metal interlayers to promote the adhesion of coatings is documented. For instance a thin titanium interlayer has been found to improve the adhesion of titanium nitride coatings deposited by a range of physical vapour deposition (PVD) processes. However, much less has been reported about coatings produced by ion beam assisted deposition (IBAD) techniques which have the advantage of low deposition temperatures (< 200-degrees-C) compared to other PVD processes. This paper describes preliminary work on the development of yttrium interlayers for IBAD titanium nitride coatings. The effects of interlayer thickness and the temperature of deposition of both interlayer and coating on the adhesion of the coatings have been determined. The reactive yttrium layer getters contamination more effectively at low temperatures than titanium and leads to improvements in adhesion over coatings with titanium interlayers deposited at the same temperature. However, the adhesion of the interlayer to the substrate is the critical factor in determining adhesion performance.