Properties of tungsten and vanadium oxides deposited by MSIP-PVD process for self-lubricating applications

The tungsten and vanadium oxides are known to be usable as solid lubricants at elevated temperatures. So far they have been used mainly as powdery materials for tribological applications or as a component of ceramics. Metal oxides are interesting for tribological insets at atmospheric conditions because of their oxidation stability. This study reports on investigations to find stable process windows for the deposition of tungsten and vanadium oxides in a reactive and non-reactive mode by the magnetron sputter ion plating-PVD-process. One focus of the study is the metal oxide phases generated in the MSIP-process under various conditions and their mechanical and metallographic properties. Coatings were deposited and analyzed by various testing methods to characterize the mechanical and structural properties, such as SEM, scratch-testing, Rockwell test, nanoindentation and XRD. Stable process windows will be presented for the reactive mode as well as the influence of different process parameters to phase generation, microstructure and the material properties. The influence of process-parameters on the deposition rate (d.c. versus r.f mode, reactive versus non-reactive mode) is of great interest to evaluate the economic relevance. It will be shown that it is possible to deposit vanadium and tungsten oxides despite target contamination effects in wide ranges by adapting the reactive gas-flow, the total gas pressure and the target power. (C) 1999 Elsevier Science S.A. All rights reserved.