Effect of bias voltage on TiAlSiN nanocomposite coatings deposited by HiPIMS

Abstract

TiAlSiN nanocomposite coatings were deposited onto cemented carbide (WC-10wt.%, Co) substrates by high power impulse magnetron sputtering (HiPIMS). The effect of substrate bias voltage on plasma discharge characterization of HiPIMS, element concentration, deposition rate, microstructure, surface/cross-sectional morphology, hardness and adhesion strength of coatings were studied. Compared with those deposited with direct current magnetic sputtering (DCMS), HiPIMS-deposited TiAlSiN coatings show improvements in some properties, including the surface roughness, the grain size, the hardness and adhesion strength, but a decrease in the deposition rate. When the bias voltage increases, the discharge current rose up from 118A to 165A. HiPIMS-deposited TiAlSiN coatings show a shift of the preferred crystallographic orientation from (220) to (200) and decreases in surface roughness from 14.1nm down to 7.4nm and grain size from 10.5nm to 7.4nm. Meanwhile, a change in crystal morphology from columnar to equiaxial and a grain refinement, as well as an increase of hardness from 30GPa up to 42GPa of those TiAlSiN coatings were observed with the increasing bias voltage and a decrease in adhesion strength from HF2 to HF5 of those coatings were revealed by indentation adhesion test.