Identification of cracks generated by indentation experiments in hard-coating systems

In this work, depth-sensing indentation measurements were applied to Zr-B-N and Zr-B monolayers as well as to multilayer systems of the same materials (two-, four- and 16-layer samples). The coatings were deposited on to Ck 35 carbon steels by reactive (Zr-B-N) and non-reactive (Zr-B) d.c. magnetron sputtering. Crack-formation processes during the penetration of the indenter were examined by analysis of the load-indentation data and by scanning electron microscopy (SEM). The analysis of the load-indentation data was performed by using averaging, smoothing and numerical differentiation procedures. Correlations between the results of the data analysis and the SEM observations are outlined, and the advantages of multilayer systems are demonstrated. (C) 1998 Elsevier Science S.A. All rights reserved.