In situ examination of wear particle generation in carbon nitride coatings by repeated sliding contact against a spherical diamond

With a pin-on-disk type apparatus installed in the chamber of an environmental scanning electron microscope (E-SEM), the motivation of this paper is to show the validity of the in situ examination to study the generation of wear particles of non-conductive carbon nitride coatings on silicon substrates under controllable relative humidity. Two typical shapes of generated wear particles can be observed in the light of in situ examination of contacting surfaces in the “wear particle generation” regime following the “no wear particles” regime. The observed two typical shapes are “feather-like wear particles” and “plate-like wear particles”, respectively. A shape transition map of wear particle generation as a function of normal loads and friction cycles is then obtained. The critical friction cycles Nc for detecting a cluster of feather-like wear particles is therefore determined from “no wear particles” to “feather-like wear particles” by the shape transition map at different applied normal loads, and is also used as the maximum value for the “no wear particles” regime for comparison. In light of the above approach to wear particle generation, the validity of using in situ examination makes further study of the effects of other important factors, such as the nitrogen incorporation conditions, coating thickness and the environments, on wear particle generation in carbon nitride coatings possible.