Tribological Behavior of Cu-Based Bulk Metallic Glass Compared to Nickel–Aluminum Bronze in Air and 3.5% Sodium Chloride Solution

The tribological behaviors of Cu-based bulk metallic glass (BMG) Cu_50.2Zr_40.8Ti_8.5Nb_0.5 and conventional nickel–aluminum bronze (NAB) reference material were investigated in air and in 3.5% NaCl solution, respectively. The tribology tests were performed at room temperature using a reciprocating tribometer at a sliding speed of 1 m min⁻¹ against a 6-mm diameter ZrO₂ ball. When sliding in air, the friction coefficient of Cu-based BMG decreases with the applied loads (5 N, 10N, and 20 N), and the wear behavior is mainly affected by abrasion, delamination, and oxidation. In particular, the wear-rate of Cu-based BMG is about 22 times lower than that of conventional NAB when sliding in the air under a load of 5 N. When sliding in 3.5 wt% NaCl solution, Cu-based BMG demonstrates better static-corrosion resistance but worse tribocorrosion resistance compared with conventional NAB. Due to the combined effects of corrosion and lubrication caused by the solution, the wear-rate of the BMG in NaCl solution increases at 5 N, but decreases at 20 N when compared with the corresponding wear in air. The tribocorrosion of Cu-based BMG is mainly controlled by abrasive wear and the synergistic effects of abrasion and corrosion. By applying −1.3 V cathodic potential, the corrosive wear-rate of Cu-based BMG at 5 N was reduced by nearly 50%. This work provides an experimental reference for the tribological evaluation of Cu-based BMG in different environments.