Use of ultramicroindentation to evaluate the degradation of sputtered coatings

The aim of this research work was to study the influence of chemical degradation on the mechanical properties of the non-degraded zones of sputtered W-N-Ti coatings. For this, an ultramicroindentation technique has been used before and after degradation, either on the zones between the pits in the corroded samples, or on the non-oxidised layers after removal of the top degraded layers. By using different applied loads it was possible to obtain results with and without the influence of the substrate. Thus, two types of results were obtained, those determined by using an empirical model, which eliminates the influence of the substrate, and those measured directly. Very small differences of less than 20% were obtained in the measured values before and after degradation, indicating that the non-degraded zones maintain their as-deposited mechanical properties. (C) 1998 Elsevier Science Ltd. All rights reserved.