Effects of multi-layer structure on microstructure, wear and erosion performance of the Cr/CrN films on Ti alloy substrate

Titanium alloy usually exhibited poor wear and erosion wear resistance. In this work, Cr/CrN films with different alternating structures of metal Cr layer with ceramics CrN layer were deposited on Ti-6Al-4V (TC4) by multi-arc planting to improve their properties. The result showed the main phases of the Cr/CrN films were Cr, Cr2N and CrN. Addition of the softer Cr layers and multi-layer structures disturbed the columnar growth of CrN layers, suppressed the CrN (111) orientation while promoted the growth of CrN (200) orientation. Also, the grain size decreased and micro-strain increased with increasing the alternating layer numbers. Compared with Ti substrate, the wear resistance of Cr/CrN coated samples significantly improved by decreasing the abrasive wear, and the Cr/CrN-10 film with alternating layer numbers of 10 showed the lower friction coefficient and higher wear resistance. The erosion experiments showed the Cr/CrN-5 film with alternating layer numbers of 5 showed the lower erosion rate, which might be due to the addition of ductile Cr layer conditioning the erosion deformation.