The erosion behaviour of TiN coatings on steels

Abstract

The erosion behaviour of physical vapour-deposited titanium nitride has been studied using both blunt particle and angular particle erodent streams. The mechanisms of erosive loss have been identified and related to the microstructure and internal stress state of the coatings. High levels of internally stored energy (which scales with coating thickness and internal stress) induce spalling in erosion testing using blunt erodents. Consequently, it is found that thick coatings are more resistant to angular particle erosion whilst thin coatings have longer lifetimes when exposed to blunt erodents. Scratch adhesion testing has been performed on all erosion specimens and attempts made to correlate the critical load for coating failure, with the failure mechanisms observed in erosive wear. Whilst no correlation can be found between erosion resistance and critical load, good correlations between the failure mechanisms found in erosion and scratch testing can be made.