Combined Acceleration of TC4 Alloy Corrosion Induced by HSO3− and AC Current in Simulated Ocean Environment
摘要
A systematic research was conducted to evaluate the anti-corrosion capacity of Ti-6Al-4 V (TC4) alloy in simulated seawater, focusing on the collective impact of alternating current (AC) and varying HSO3− concentrations. The results reveal that the increased HSO3− content and AC current density impair the passivation ability of the alloy and enhance its pitting susceptibility, as demonstrated by elevated ip and pitting number as well as declined Ep. The imposition of alternating current disturbs the formation and stabilization of surface passive layer, which is verified by the presence of transition zone and significantly increased donor density. The addition of HSO3− induces the production of small pores within the surface film, deteriorating its compactness and completeness, which promotes the occurrence of numerous shallow corroded areas. The combined effect of AC and HSO3− leads to the generation of large-sized holes inside the passivation film, which markedly reduces its protective ability. This work clarifies the degeneration mechanism of TC4 alloy under the joint influence of iAC and HSO3− on anti-corrosion property, filling the research gap regarding the AC corrosion behavior of the alloy in SO2-contaminated marine environments.