Structure-property relations of arc-evaporated Al-Cr-Si-N coatings

摘要

The addition of silicon to the widely used aluminum-containing transition metal nitrides is promising for the synthesis of hard and thermally stable films with good oxidation resistance. For that reason, Al-Cr-Si-N coatings were deposited by reactive cathodic are-evaporation under industrial conditions from Al70Cr30-xSix (x=0, 1, 2, 5 at.%) targets at substrate bias voltages ranging from -40 V to - 150 V. The structure of the well adherent coatings was investigated by X-ray diffraction and Raman spectroscopy, which indicated at higher Al/Cr ratio > 1.9 an increased tendency of the metastable face-centered cubic solid solution of AlN in CrN to separate into a cubic-hexagonal phase mixture. At higher bias voltages, this effect is 1,gradually inverted and the single cubic phase can be retained. X-ray photoelectron spectroscopy revealed dominant Si-N bonds suggesting either a substitutional solid solution or a separate Si-N phase. Mechanical properties, i.e. hardness and elastic modulus, measured by indentation together with stress evolution demonstrate the beneficial effect of the conservation of the metastable cubic phase. (c) 2008 Elsevier B.V. All rights reserved.