Monel 400 alloy is widely employed in marine engineering equipment due to its excellent corrosion resistance, high strength and toughness. In this paper, the tribo-corrosion behavior of Monel 400 alloy in seawater under different rotational velocities was investigated by a pin-disk tribometer with an integrated electrochemical cell. The results revealed that the material loss rate and friction coefficient of the Monel 400 alloy, after tribo-corrosion and mechanical wear tests, increased with increasing rotational velocity. Under mechanical-wear conditions, the material loss
rate increased with the sliding distance extension at higher velocities, and then more serious crack nucleation and propagation occurred at the subsurface. Under tribo-corrosion conditions, when the rotational velocities increased from 0.125 m/s to 0.5 m/s, the thickness of the corrosion product's layer was reduced from 50 nm to 30 nm; that is, the lubrication of the corrosion product became worse. As a result, the material-loss rate and friction coefficient increased significantly at the velocity of 0.5 m/s. Importantly, the antagonistic effect, rather than the synergistic effect, between corrosion and mechanical wear, has been verified for the tribo-corrosion of Monel 400 alloy in seawater, and the mechanism was analyzed