Tribocorrosion behavior of 316L stainless steel in alternating wet and dry environments

In marine equipment, some moving stainless steel components are designed to work in both seawater and air. These components would be suffered tribocorrosion under wet-dry alternation. This study investigated the tribocorrosion behavior of 316L stainless steel in alternating wet and dry environments. The stainless steel was worn in a saline solution and air with varying percentage of wet-dry alternating cycle time and the number of alternating cycles. The findings indicated that cyclic wet-dry alternation accelerated the tribocorrosion degradation rate of the stainless steel comparing with that in the immersing condition. The formation of a thin electrolyte film on the stainless steel after it was transferred from the solution to the air was the key factor responsible for the acceleration. The evaporation of water diminished the electrolyte film thickness, thereby shortening the diffusion path of oxygen between the air and the stainless steel/electrolyte interface, and rised the chloride concentration, which accelerated the cathodic reaction and promoted the anodic reaction, respectively. This finally led to enhancement of the synergy between corrosion and wear, and the acceleration of the degradation of the stainless steel. The increase of wet-dry alternation frequency or wet-dry ratio would weaken the accelerating effect, because it shorted water evaporation time, and limited electrolyte film thinning.