Influence of bias voltage on the hardness and toughness of CrAlN coatings via magnetron sputtering

Chromium aluminum nitride (CrAlN) coatings were prepared via magnetron sputtering in a mixed Ar and N-2 ambient. The effect of negative bias voltage (V-b) on the microstructure was investigated using a spectrum of characterizing techniques in terms of Glancing Angle X-ray Diffractometry, Field Emission Scanning Electron Microscopy and Transmission Electron Microscopy. As V-b increased from 50 to 260 V. hardness was improved from 10 to 26 GPa. Toughness grew at the same time and maximized at around 2 MPa . m (1/2) when V-b = 210 V. Simultaneous improvements in hardness and toughness were attributed to the densified microstructure with refined grains and increased compressive stress. (C) 2012 Elsevier B.V. All rights reserved.