【作者】 赵婷婷；

【导师】 齐公台；

【作者基本信息】 华中科技大学 ， 应用化学， 2007， 硕士

【摘要】 合金化是使铝用于阳极的必需途径,研究合金元素对铝阳极性能及溶解规律的影响,尤其是找出适用于高温条件下的铝合金牺牲阳极,一直倍受国内外研究者的关注。本文熔炼了Al-5Zn-0.026In、Al-5Zn-0.026In-0.1265Si、Al-5Zn-0.026In-0.1265 Si-0.047Zr三种阳极,在3%NaCl溶液,20℃及65℃下进行电化学性能测试,采用电子探针(EMPA)和能谱分析技术考察了三种铝阳极的微观结构及偏析相的组成,研究了阳极中典型偏析相与电极组成电对的电偶腐蚀规律,测试了偏析相和阳极的析氢速率,探讨了合金元素对铝合金牺牲阳极微观组织和宏观电化学性能影响的规律性。实验结果表明:添加的In能有效活化铝合金表面,其与Zn组成的In-Zn相是Al-Zn-In合金优先活化点;添加的Si与Fe形成化合物,增加了铝阳极的电化学不均匀性,增加了晶粒脱落造成的铝阳极电流效率的损耗;添加的Zr能明显细化晶粒,净化铝合金内部组织,改善铝合金电化学不均匀性,能使阳极均匀腐蚀,在高温条件下,由于电化学不均匀性的降低,阳极自损耗减少,从而提高了铝合金牺牲阳极的电流效率。通过对偏析相与铝合金电偶腐蚀测试的研究发现:阳极性的偏析相(In-Zn相)与铝合金基体组成腐蚀微电池,造成了阳极的自损耗,当周围的基体腐蚀完毕后导致晶粒易脱落,造成机械损失;阴极性的偏析相(Zn-Al)与铝合金基体组成的腐蚀微电池中,铝合金基体得到保护,但其上明显出现的析氢自腐蚀引起阳极电流效率的损耗,这种情况随着温度的升高明显增强,导致阳极性能明显变差。更多还原

【Abstract】 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.更多还原