BEHAVIOR OF CVD AND PVD COATINGS UNDER IMPACT LOAD

The impact test is a new test method to determine the impact load of c oated substrates. Chemical (CVD) and physical vapour deposition (PVD) coatings on cemented carbide substrates have been tested. The descript ion of the stress distribution in the coating-substrate compound gives important information for understanding the test results. The differe nt kinds of coating damage can be explained by different stress models . Under impact load PVD and CVD coatings show totally different behavi ours. While PVD coatings are damaged suddenly, CVD coatings show a con tinuously increasing wear mark. Based on stress analysis, a model has been developed which can explain the different behaviours of PVD and C VD coatings in the impact test. Practical wear tests (interrupted cutt ing test) show the relevance of the impact test. A comparison with oth er test methods, e.g. the scratch test, shows the delimitation of the test.