Effects of WC mass fraction on microstructure and tribological behavior of plasma sprayed FeMnCoCr–WC coatings

Abstract

FeMnCoCr–WC coatings with WC mass fractions of 0 %, 5 % and 10 % were prepared on Ti6Al4V alloy by plasma spraying to improve the tribological properties of FeMnCoCr coating. The effects of WC mass fraction on the microstructure, chemical elements and phases of obtained coatings were analyzed via a scanning electron microscope, super–depth of field microscope, energy dispersive spectrometer and X–ray diffraction, respectively, and the wear behavior of FeMnCoCr–WC coatings at room temperature and 500 °C was also evaluated using a ball–on–disc wear tester. The results show that the WC addition improves the coating hardness through the grain refinement, and the coefficients of friction (COFs) and wear rates of coatings are decreased with the increase in WC mass fraction at room temperature and 500 °C. The wear rates of FeMnCoCr–WC coatings at 500 °C are increased compared with those at room temperature, which are attributed to the softening effect and plastic deformation at high temperature. The wear mechanism of FeMnCoCr–WC coatings at RT is changed from adhesive wear + oxidative wear + abrasive wear to abrasive wear + delamination wear + oxidative wear as the WC mass fraction increases; while those of at 500 °C are not changed with the increase in WC mass fraction.