High temperature friction and wear behaviour of sputter-deposited nanocrystalline (Mo xCr 1− x) 5Si 3 films by a double cathode glow discharge technique

Abstract

In order to improve the wear resistance of titanium alloys, five kinds of sputter-deposited nanocrystalline (Mo x Cr 1− x ) 5Si 3( x = 1, 0.78, 0.75, 0.64, 0.57) films with average grain size 8 nm were fabricated on a substrate of Ti6Al4V alloy by means of a double cathode glow discharge technique. The microstructure and composition of the as-deposited films were characterized by scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and energy dispersive spectrometer (EDS). Nanoindentation was used to measure hardness ( H) and elastic modulus ( E) of the as-deposited films. High temperature friction and wear properties of the as-deposited films were investigated against ZrO 2 ceramic balls by a ball-on-disk system at 600 °C. Compared with the Ti6Al4V alloy, the friction coefficient values of the nanocrystalline (Mo x Cr 1− x ) 5Si 3 films were reduced by 0.2–0.3, and specific wear rates decreased by two orders of magnitude and were around or lower than 10 −6 mm 3/(N m) at the load ranging from 3.3 N to 4.8 N. The friction coefficient and specific wear rates of the as-deposited films relied on the Cr content in the nanocrystalline (Mo x Cr 1− x ) 5Si 3 films, and the higher the Cr content, the lower friction coefficient and wear rates.