Erosive wear properties of Ti–Si–N nanocomposite coatings studied by micro-sandblasting

Abstract

Superhard Ti–Si–N nanocomposite coatings were deposited on high speed steel substrates by a combined dc/rf unbalanced reactive magnetron sputtering process. Erosion tests using angular Al2O3 particles (mixture of cylindrical and trihedral particles) with an average particle size of 17μm were carried out using air-sand blasting to investigate the erosive wear properties of the coating. For benchmarking purpose, three other hard or superhard coatings, namely, TiN, nanolayered TiN/NbN and multiple-layer CrTiN/NbN have also been evaluated under the same experimental conditions. In the air pressure range used in this work from 1.3 to 4.2 bar, the nanocomposite Ti–Si–N coatings demonstrated extremely low steady-state erosion rates compared with the other three coatings evaluated. However, pinholes associated with the particle impacts were observed in the tests of Ti–Si–N coating, which propagated with the increase of air pressure or particle velocity and the particle impingement duration, and eventually led to coating failure. The erosive failure mechanism and the dependence of the erosion rate on coating properties and experimental conditions were discussed based on the microstructural analysis.