Influences of oxidation and hot corrosion on the tribological properties of CoCrNiWMo alloy and the preliminary exploration of the interaction between hot corrosion and wear

The phase composition and microstructure evolution of oxide layer formed on the CoCrNiWMo alloy after oxidation was investigated in 75 wt% Na2SO4 + 25 wt% NaCl molten salts at 800 ◦C. The oxidation products and
the structure of the oxide layers of bare and salt-coated CoCrNiCoMo alloy presented significant differences. The oxide layer formed on bare alloy was a single (Cr, O)-rich layer, whereas the oxide layer formed on salt coated
alloy was a hierarchical structure with two sub-layers. The worn oxide layer on bare alloy exhibits a similar structure to the static oxide layer, which effectively reduces wear. As with static corrosion, dynamic wearcorrosion
formed a hierarchical corrosion layer, which was covered in the outermost layer by a thin layer of (Mo, Co, O)-rich oxides. Molten salts promoted rapid degradation of the substrate and friction layer, which facilitated more friction chemistry, but worsened the wear resistance.