Effect Of Solution Treatment On Anodic Dissolution Behavior Of Al-Zn-Sn System

Aluminum has been widely used as an anode material because of its negative standard electrode potential,high theoretical specific capacity,light weight and abundant resources.As important alloying elements of aluminum anode material,Zn and Sn can significantly improve the performance of aluminum anode and reduce the self-corrosion rate while destroying the passivation film on aluminum surface.Corrosion solubility is an important performance index of aluminum anode.In order to further study the influence of Zn and Sn elements alone,compound addition and solution treatment on the corrosion activation of Al alloy,seven alloy components(Al,Al-6Zn,Al-3Sn,Al-0.4Sn,Al-6Zn-x Sn(X=0.1,0.2,0.4)were smelted.The corrosion dissolution behavior was studied by microstructure and composition analysis,corrosion evolution observation and electrochemical performance test.In this paper,the effect of Zn and Sn addition on Al corrosion behavior was first studied.The results show that Zn and Sn are ideal corrosion passivation elements for aluminum alloy,and Al-6Zn and Al-3Sn have good corrosion dissolution activity in the as-cast state.The segregation of Zn and Sn at grain boundaries leads to the preferentially corrosion occurring at grain boundaries.The activation effect of Sn on aluminum is greater than that of Zn,and Sn content has an important effect on aluminum activation.The active order of the four components in as-cast aluminum alloy is Al<Al-0.4Sn<Al-6Zn<Al-3Sn.The solution treatment at 550℃ has different effects on the corrosion dissolution of Al-6Zn,Al-3Sn and Al-0.4Sn.The solution of Sn in aluminum matrix significantly improves the corrosion solubility of Al-0.4Sn.However,after Zn is solidly dissolved in aluminum matrix,the disappearance of Zn-rich active sites at grain boundaries leads to the slow corrosion development of Al-6Zn,but the dissolution morphology is more uniform.The enrichment of Sn at grain boundaries after solution results more serious grain boundary corrosion of Al-3Sn than that in as-cast state.The influence of as-cast condition with three process of 450℃×4 h,500℃×4 h and550℃×4 h solution treatment on the corrosion dissolution behavior of Al-6Zn-x Sn were investigated.The solubility and distribution of Sn in aluminum matrix were controlled by different solution temperatures.The results show that the dissolution activity of Al-6Zn-x Sn in as-cast state is ranked as follows: Al-6Zn-0.1Sn < Al-6Zn-0.2Sn < Al-6Zn-0.4Sn.With the increase of Sn content,the grain boundary corrosion sensitivity gradually increases.Zn and Sn have a good synergistic activation effect on aluminum.The solution treatment at 450℃ is unfavorable for improvement of the corrosion solubility of Al-6Zn-XSn,which is related to the coarse grain size and low Sn solubility.Al-6zn-0.1Sn has the best dissolving discharge performance at 500℃,and its activity is close to that of Al-6Zn-0.2Sn and Al-6Zn-0.4Sn with high Sn content.Al-6Zn-0.2Sn obtained the best corrosion activity at 550℃,but the solution treatment did not improve the corrosion solubility of Al-6Zn-0.4Sn.This paper provides some guidance for the development of Al-Zn-Sn series anode materials.Increasing the content of Sn properly can improve its solubility in the as-cast state.For Al-Zn-Sn anode with low Sn content,solution treatment is an effective means to improve its dissolution activity.Meanwhile,low solution treatment temperature should be avoided.