Influence of phase transition on the tribological performance of arc-evaporated AlCrVN hard coatings

V-alloyed AlCrN hard coatings were synthesised by reactive arc-evaporation in an industrial-sized deposition system at bias voltages ranging from -40 to -150 V. X-ray diffraction analysis has shown that higher energetic growth conditions stabilise the desired metastable face-centered cubic (fcc) crystal structure of Al0.70Cr0.05V0.25N even at very high Al/Cr ratios resulting in hardness values comparable to Al0.70Cr0.30N. Ballon-disc tests were used to assess the friction at 700 degrees C where Al0.70Cr0.05V0.25N coatings revealed a generally lower coefficient of friction due to the formation of a tribolayer containing the lubricious oxide V2O5 as evidenced by Raman spectroscopy. The single-phase fcc-Al0.7Cr0.05V0.25N coating appears to be more oxidation resistant leading to a reduced formation Of V2O5 and, hence, an increase in friction. The cutting performance was evaluated by conducting side milling tests under dry conditions, where Al0.70Cr0.05V0.25N coatings showed a competitive performance regardless of the growth conditions. (C) 2008 Elsevier B.V. All rights reserved.