Microwear mechanisms of coatings

Microwear mechanisms of coatings are studied by focusing attention on mechanical wear. Wear rates and wear modes of chemically vapour-deposited TiN and Al2O3 coatings in abrasive sliding are observed experimentally with a scanning electron microscope which has a videotape recording system and a tribosystem. It is shown that the wear rate changes by factors of 3-5 orders of magnitude depending on load and friction cycle. Wear modes of ploughing, powder formation, flake formation and coating delamination are observed and their transitions are related to the change of load and friction cycle. For the prediction of possible wear modes, a new local yield map is proposed by taking into account the stress analysis at the contact region with the finite element method.