Effect Of Zr,Si Alloying Elements On Electrochemical Performance And Dissolution Behavior Of Series Of Al-Zn-In Alloy Sacrificial Anode

It was necessary to alloy the aluminum with many alloying elements; the researchers had been making attention on the research about the performance and dissolutive rule of aluminium anode, especially the aluminum alloy sacrificial anode which could be used in high-temperature circumstance.Three kinds of anode material Al-5Zn-0.026In, Al-5Zn-0.026In-0.1265Si, Al-5Zn-0.026In-0.1265Si-0.047Zr had melted. The electrochemical performances of the three anodes had been tested in the 3% NaCl solution at 20℃and 65℃. By using the EMPA and energy spectrum, the micro-structures and the compositions of these three anodes had been investigated. The affections on which the typical segregations acted had been discussed through the galvanic corrosion and the hydrogen evolution. By the means of comparing the anodic performance under the different temperatures (20℃and 65℃), the rule between the micro-structure and macro-electrochemical performance had been researched. The galvanic corrosion of aluminum alloy coupled with different typical segregations had been discussed further.The results showed that the presence of In as a segregated phase at the grain boundaries or as an In rich phase in the interdendritic zones of the grains promotes higher dissolution rates. The attack initiation of the Al-Zn-In alloy is related to In-Zn rich zones, located at grain or cell boundary; the added Si coupled with Fe rise the non-uniform electrochemistry and the efficiency loss by fail out of grain; the alloying component of Zr could thin the crystal grains of aluminum alloy, so to decreased the non-uniform electrochemical performance, which in turn reduced the ullage of the anode so that the current efficiency was increased.By the means of researching on the galvanic corrosion between the segregations and the aluminum alloying, the results showed that the anodic segregation (In-Zn) coupled with aluminum alloying formed a corrosive cell which leaded to the loss of anode, when the parts around the grain consumed, the grain would fall and the current efficiency lost by fall out of grains increased; cathodal segregation (Zn-Al) could protect the aluminum contrarily, the hydrogen evolution was aggravated so that the current efficiency decreased. As the temperature increased this situation became obviously which lead to the anodic property depravated.