Research On Property Of Al-Zn-In Sacrificial Anode Under Simulate Deep Sea Water

Al-Zn-In sacrificial anodes are the most common anodes which are used to protect metalmaterials in marine environment. The equipments worked in oceans will suffer shallow-deepsea water alternate cyclic environment. The corrosion behavior of sacrificial anode under thisservice condition is still unclear. So it is important to study the properties of Al-Zn-Insacrificial anodes under shallow-deep sea water alternate cyclic environment and the factorswhich influence it under deep sea water, in order to develop some new sacrificial anodes andimprove the reliability of sacrificial anode protection under deep sea water environment.In this work, we investigated the corrosion behavior of the Al-Zn-In sacrificial anode inshallow sea water and shallow–600m deep sea water alternate cyclic environment. It wasindicated that the working potential and open circuit potential of Al-Zn-In sacrificial anodewere instantaneously responded with the cyclic of environment under shallow–600m deepsea water alternate cyclic environment and shifted positive under the deep sea waterenviroment. The current efficiency of anode under shallow-deep sea water alternate cyclicenvironment was reduced by14.83%compared with that in the shallow sea environment.High hydrostatic pressure, less oxygen, and low temperature are the main differencesunder deep sea water which compared with the shallow sea environment. Under600m deepsea water environment, the electric quantity and current efficiency of Al-Zn-In sacrificialanode were decreased sharply compared with the shallow sea water environment. Highhydrostatic pressure accelerated intergranular corrosion of the sacrificial anode while lowoxygen and low temperature caused the passivation of the sacrificial anode. The order ofeffect degree of environmental factors on the sacrificial anode was: oxygen <hydrostaticpressure <temperature.In³⁺ in solution could accelerate the active dissolution process of sacrificial anode,reduce grain boundaries corrosion and improve the electric quantity and current efficiency ofsacrificial anode under deep sea water environment; but Zn²⁺ did not have this function.For further study of the effect of In alloy element on Al-Zn-In sacrificial anode as alloycomponent. We casted0.04%In,0.06%In,0.08%In sacrificial anode. The results showedthat, as In elements increased，the open circuit potential of Al-Zn-In sacrificial anode shiftedto more negative, the passivation phenomenon was abated under deep sea water environment. The electric quantity and current efficiency of0.08%In sacrificial anode were improvedsignificantly under deep sea water environment.