The Tribo-Corrosion Behavior of Monel 400 Alloy in Marine Environment at Varied Rotational Velocities

Abstract

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.