Failure mechanism of Al-Zn-In sacrificial anode under the synergic action of water pressure and fluid in the extreme deep-sea environment

Corrosion failure of sacrificial anodes in extreme deep-sea environment is a key problem in metal protection technology. This study investigated the failure mechanism of the Al-Zn-In sacrificial anode under the synergic action of water pressure and fluid flow, by microstructure characterization and finite element analysis. The results exhibit that water pressure promotes the dissolution of Al-Zn-In alloy near the precipitates that are enriched at the grain boundaries. The flow amplifies the promoting effect of the pressure on anodic dissolution by inhibiting the formation of corrosion layers, and it accelerates the mass loss by mechanically aggressing the aluminum matrix. The synergic effect of water pressure and fluid flow results in a rapid degradation in the extreme deep-sea environment.