An Introductory Course for Nanoindentation of Hard Coatings

Nanoindentation is a widely used technique for measuring mechanical properties at small scales, including films and coatings. Here, the technique for measuring tooling coatings is detailed thoroughly from beginning to end. These PVD and CVD coating are used as an example that combines finding a balance between the requirements of roughness, thickness, and extraordinary hardness. 

There are many considerations with regards to how the nanoindentation technique should be performed that are not immediately understood by the introductory user. Starting from the beginning, the measurements of hardness and modulus on a simple substrate is presented. However, measuring real samples rarely matches this ideal. Deviations from this ideal are then introduced by measuring samples with finite roughness and coating thickness. Essentially, these complications are in conflict as increasing measurement depth will mitigate the effect of roughness but will gradually give a mixed response of the coating and underlying tooling substrate. Thus, choosing the optimum depth is important for getting accurate measurements of the tool coating. Results on four different commercially available nitride coatings are presented.