Load sensitivity in repetitive nano-impact testing of TiN and AlTiN coatings

A key step in optimisation of coating behaviour is to understand the relationship between a range of parameters that can easily be obtained in the repetitive nano-impact test and ultimate coating performance in demanding applications. In this study we have performed a statistical analysis of multiple repetitive impact tests on advanced nitride coating systems and have identified the key parameters that can be used to assess durability and wear resistance. At lower load the coating mechanical properties and microstructure are beneficial in providing improved impact resistance. At higher load the initial impact resistance is also enhanced in non-columnar coatings with higher resistance to plastic deformation but their limited ductility can affect their damage tolerance under continued impact.