Properties of various large-scale fabricated TiAlN- and CrN-based superlattice coatings grown by combined cathodic arc-unbalanced magnetron sputter deposition

TiAlN and CrN are gaining increasing importance in many industrial applications. To improve their mechanical and tribological properties further, these materials have been deposited to form 3 mu m thick superlattice structures of TiAlN-CrN (period 3.8 nm). The structural and tribological characteristics of TiAlN-VN (period 3.0 nm) and CrN-NbN (period 3.7 nm) have also been studied in comparison with TiAlN-CrN and monolithic TiAlCrN and CrN alloys. All coating were deposited using the combined steered cathodic are-unbalanced magnetron deposition method. The superlattice coatings generally showed increased hardness value and considerably reduced sliding and micro-abrasive wear compared with TiAlCrN and CrN. In the case of superlattice structured films TiAlN-VN films showed exceptional performance in dry sliding wear tests and, generally, all TiAlN-based films performed well in micro-abrasive wear trials. Corrosion tests revealed that CrN-NbN coatings exhibited clear passivation characteristics with considerably better corrosion resistance than stainless steel and significantly lower passive current density than electroplated hard chromium. (C) 2000 Elsevier Science S.A. All rights reserved.