Behaviour of CVD and PVD coatings under impact load

Abstract

The impact test is a new method to determine the impact load of coated substrates. Chemical (CVD) and physical vapour deposition (PVD) coatings on cemented carbide substrates have been tested. The description of the stress distribution in the coating-substrate compound gives important information for understanding the test results. The different kinds of coating damage can be explained by different stress models. Under impact load PVD and CVD coatings show totally different behaviours. While PVD coatings are damaged suddenly, CVD coatings show a continuously increasing wear mark. Based on stress analysis, a model has been developed which can explain the different behaviours of PVD and CVD coatings in the impact test. Practical wear tests (interrupted cutting test) show the relevance of the impact test. A comparison with other test methods, e.g. the scratch test, shows the delimitation of the test.