锌电积用新型铅基合金阳极的制备及性能研究

【作者】 曹远栋；

【导师】 郭忠诚；

【作者基本信息】 昆明理工大学 ， 有色金属冶金， 2009， 硕士

【摘要】 电积锌工业中,目前广泛使用Pb-(O.8～1)%Ag合金作为阳极,其优势地位尚无法完全被取代。由于银是一种昂贵的金属,因此长久以来冶金工作者一直致力于研究在不影响铅银合金综合性能的情况下通过加入其它合金元素来降低银含量,以达到节约成本的目的。Ca、Sr、RE等元素被证实能较好的提升铅银合金的综合性能,并且能弥补银的损失。非混溶系合金具有一些优异的性能,如铅和铝在性能上有很好的互补性,正是基于此点,本课题研究了在铅合金中加入铝钛硼合金,并通过测试合金的力学、抗腐蚀、以及电化学性能来探究铝的加入对铅基合金阳极性能的影响,根据查阅的文献,目前尚无相关报道。本文首先通过分析铅-铝系相图,探讨了得到成分均匀的铅铝合金所需的热力学及动力学条件。采用重力浇铸法,在一定条件下制备了铅银、铅钙、铅稀土中间合金,最后配制成标准合金,得到了Pb-1%Ag、Pb-0.15%Ag-0.11%Al、Pb-0.15%Ag、Pb-0.11%Al、Pb-0.3%Ag-0.06%Ca-0.05%Ce合金阳极。通过观察铅基合金的金相,发现铝钛硼合金的加入,细化了铅的晶粒,铝呈第二相形式分布在铅基体中,存在着较大的偏析。研究了铅合金的硬度、抗拉强度、断后延伸率等力学性能,结果表明铝钛硼合金的加入提高了铅的硬度,其中添加了铝钛硼合金的Pb-0.11%Al合金的硬度比纯铅的硬度高0.22kg/mm2；Pb-0.15%Ag-0.11%Al的硬度要比Pb-0.15%Ag高0.35kg/mm2,Pb-0.11%Al比纯铅的抗拉强度高3.2N/mm2,从而得出,铝钛硼的加入提高了铅的抗拉强度。分别在ZnSO4-H2SO4和ZnSO4-MnSO4-H2SO4体系中研究了Pb-0.15%Ag-0.11%Al、Pb-0.15%Ag、Pb-1%Ag、Pb-0.3%Ag-0.06%Ca-0.05%Ce的阳极腐蚀速率以及在ZnSO4-H2SO4体系极化48h阳极氧化膜形貌和物相组成。在以上两种体系中Pb-0.15%Ag-0.11%Al的耐蚀性均要好于Pb-0.15%Ag,但较Pb-1%Ag、Pb-0.3%Ag-0.06%Ca-0.05%Ce合金的耐腐蚀性差。通过稳态极化曲线、循环伏安、交流阻抗研究了合金的电化学性能。通过稳态阳极极化得出Pb-0.15%Ag-0.11%Al在ZnSO4-H2SO4体系中的阳极析氧电位最低,表现出良好的催化活性。通过交流阻抗分析可知,Al掺杂在铅合金中有利于提高合金的活性,尤其是阳极极化24h后的Pb-0.15%Ag-0.11%Al和Pb-0.11%Al阳极表面的催化活性好。更多还原

【Abstract】 Lead alloys containing 0.8～1% silver is widely used as insoluble anodes in zinc electrolysis industry. However, as silver is a very expensive element, scientists made a lot of efforts to look for other alloy elements to supplement the miss of Ag in the lead alloys while not harm its comprehensive performances. Such alloy elements like Ca、Sr、RE were investigated and proved to be effective when alloyed with lead. Given some of the excellent properties of the immiscible alloy, comprehensive performance including mechanical, corrosion resistance and electrochemical properties of lead alloys by adding Al-Ti-B to the Pb-Ag alloy were investigated, according to our knowledge, no report was found in this area.By analyzing the Pb-Al Phase diagram, the thermodynamics and kinetics conditions for obtaining uniform distributed Al in Pb substrates were discussed. By applying the galvanic casting method, fistly, Pb-Ag, Pb-Ca, Pb-RE masteralloy were prepared, then, several kinds of lead alloys:Pb-1%Ag, Pb-0.15%Ag-0.11%Al, Pb-0.15%Ag, Pb-0.11%Al, Pb-0.3%Ag-0.06%Ca-0.05%Ce were obtained by remelting the masteralloy with pure lead.Through metallographic study, it was find that the grain size of the lead was decreased by alloying Al-Ti-B, Al was observed as second-phase distributed in the lead alloys substrate unevenly.By study the mechanical properties like Brinell hardness, tensile strength and elongations of these lead alloys, it was concluded that the introduce of Al-Ti-B improved the mechanical properties of the alloy.Corrosion velocity of these alloys:(Pb-0.15%Ag-0.11%Al, Pb-0.15%Ag, Pb-1%Ag, Pb-0.3%Ag-0.06%Ca-0.05%Ce)were investigated in both ZnSO4-H2SO4 and ZnSO4-MnSO4-H2SO4 system, the result show that Pb-0.15%Ag-0.11%Al was more resistant to Pb-0.15%Ag, but inferior to that of Pb-1%Ag and Pb-0.3%Ag-0.06%Ca-0.05%Ce.Stable polarization curves shows that the fresh Pb-0.15%Ag-0.11%Al alloy in system has the lowest anodic polarization overpotential, which means the best catalytic activity. EIS results convey that aluminum helps to improve the catalytic activity of lead alloys, especially after polarization for 24h.更多还原