Sliding wear of spark plasma sintered CrFeCoNiCu high entropy alloy coatings with MoS2 and WC additions

Using spark plasma sintering (SPS), the coatings of CrFeCoNiCu high entropy alloy (HEA) and its composites with MoS2 and WC additions were sintered on carbon steel substrate, respectively. The dry sliding wear behavior of the HEA coatings was investigated using a ball-on-disk sliding tribometer with a silicon nitride ball. The wear mass loss and the coefficient of friction (COF) increased greatly with the normal load increased. 2 wt.% MoS2 addition is beneficial to decrease the COF as well as the wear rate of HEA coatings. However, adding more MoS2 induce to larger wear rate though the COF decreases continually. On the other hand, adding 50 wt.% WC, the mass loss and COF of this HEA coating decreased obviously. So WC addition is also beneficial to decrease wear rate as well as the COF. The composite coating with 80 wt.% WC has the lowest wear rate 0.7 mg under 30 N normal load, which is more than 16 times lower than that of HEA coating without additions. The worn surface observation for the HEA coatings shows MoS2 addition leads to the wear mechanism evolution from two-body wear to three body wear and delamination wear is the domain wear mechanism of WC/HEA. Therefore, SPS sintered CrFeCoNiCu HEA coating possesses outstanding wear resistance, and the wear rate and COF can be extremely decreased by adding MoS2 and WC.