【作者】 龙萍；

【导师】 李庆芬；

【作者基本信息】 哈尔滨工程大学 ， 材料学， 2006， 硕士

【摘要】 在海水循环冷却系统中，换热设备出口处海水的温度较高，腐蚀特别严重，因此解决该设备的高温海水腐蚀问题就显得尤为重要。牺牲阳极保护法是防止海洋设施腐蚀的一种行之有效的保护方法，但是常用的几种牺牲阳极材料在高温时却面临着电位上升，电流效率下降，并存在晶间腐蚀等诸多问题。本课题正是在这样一个背景下提出来的，目的在于研制出高温高效的铝、锌合金牺牲阳极材料。根据前人的研究结果，首先确定了14种牺牲阳极配方进行熔炼。在铝阳极和锌阳极中各选取一种材料进行固溶处理，然后对所有牺牲阳极进行电化学性能测试，并将国标作为阳极配方筛选的参考依据，同时考察了合金元素和热处理对阳极电位、电流效率、表面溶解状况及晶间腐蚀的影响。实验结果表明，在60℃时，阳极材料Al-6.55Zn-0.023In-0.17Si-0.028Sn(Al5)、Al-5.8Zn-0.074In-0.092Bi-0.028Ti(Al6)、Zn-0.0006Al-0.05Cd(Znl)、Zn-0.43Al-0.48Cd(931)，以及在70℃时，阳极材料Al-6.53Zn-0.024In-0.19Si(929)、Al-5.43Zn-0.024In-0.05Sn(930)、Zn-0.0006Al-0.05Cd(Znl)，其电化学性能均较理想，可以作为适用于热海水环境下进一步开发的阳极材料。在对两种阳极材料Al-Zn-In-Si和Al-Zn-In-Si-Sn对比研究中发现，加Sn的优点是可以消除阳极在低温时的晶间腐蚀，并使阳极高温时的电位负移。但其缺点是使高温时阳极电流效率有所下降，且电位变得不很稳定，表面腐蚀均匀性变差。根据研究结果，高温时铝、镁等合金元素的存在对锌阳极电化学性能有不利影响。通过进一步考察分析铝对Zn-Al-Cd阳极晶间腐蚀的影响，得出了两个结论：在晶界区存在的活跃的铝原子是高温时Zn-Al-Cd阳极发生晶间腐蚀的必要条件，而析氢反应对晶间腐蚀起着“催化”作用，并加剧了晶间腐蚀的发生。在研究固溶处理对在高温时锌、铝阳极性能的影响时发现，固溶处理能够改善Al-Zn-In-Si-Sn阳极的电化学性能。但对于Zn-Al-Cd阳极，固溶处理反而使其性能下降。在对Al-2.98Zn-0.02In-1.24Mg阳极进行恒电流法和自放电法的实验中发现，大电流密度有助于提高铝阳极的电化学性能。自放电法的实验结果也进一步证实了Al-6.55Zn-0.023In-0.17Si-0.028Sn和Al-5.8Zn-0.074In-0.092Bi-0.028Ti在高温下具有良好的电化学性能。更多还原

【Abstract】 There exists serious corrosion in the place of outlet of heat exchange equipment in circulation and cooling system, in which seawater temperature is rather high. And so it is a special significance that the problem of the equipment attacked is solved under high temperature seawater. The sacrificed anodes protection is a kind of effective methods widely used for prevention marine structures from corrosion. However, several kinds of sacrificed anodes in common use are of many difficulties such as increased potential, decreased efficiency, intercrystalline corrosion and so on. This task is proposed on the basis of above background, which aims to develop aluminum-based and zinc-based sacrificed anode materials of high efficiency used for high temperature environment.According to precursor’s research, we determined 14 kinds of sacrificed anode composition to melt. A kind of material was chosen respectively from aluminum-based and zinc-based anodes for solution treatment tests. The electrochemical property tests were undertaken; the national standards are references for selecting anode composition. Meantime, these effects of alloy elements and solution treatment on potential, current efficiency, surface dissolution and intercrystalline erosion were studied.Experimental results show that Al-6.55Zn-0.023In-0.17Si-0.028Sn, Al-5.8Zn-0.074In-0.092Bi-0.028Ti, Zn-0.0006Al-0.3Cd, Zn-0.43Al-0.5Cd at 60°C and Al-6.53Zn-0.024In-0.19Si, Al-5.43Zn-0.024In-0.05Sn, Zn-0.05Cd at 70°C have good electrochemical behavior, and can be used for hot seawater environment as anode materials to develop further.Comparison on anodes both Al-Zn-In-Si and Al-Zn-In-Si-Sn, the addition of Sn is found that can decrease or remove intercrystalline corrosion at low temperature. At high temperature, however, it causes current efficiency lower, potential little stable and bad uniform dissolution of anode surface beyond greater electronegative potential provided.According to the studying result, the addition of alloy elements such as aluminum or magnesium has disadvantageous effect on the properties of zinc alloy anodes at high temperatures. After further analyzing effects of Al on intercrystalline corrosion of Zn-Al-Cd, we draw two conclusions that aluminum atoms activated in the area of grain boundary are essential to result in intercrystalline corrosion; moreover, separating-hydrogen reaction catalyses and aggravates it.Based on observing influence of solution treatment on properties of zinc-based and aluminum-based sacrificed anodes at high temperatures, it has been found that solution treatment can improve electrochemical behaviors of Al-Zn-In-Si-Sn anode. As to Zn-Al-Cd after solution treatment, however, solution treatment causes its behaviors worse.The experimental results exhibit that great current density helps in improving catholic-protection behavior of aluminum anodes on the basis of the self-discharge experiment for Al-2.98Zn-0.02In-l.24Mg compared to the constant current density experiment for it. In addition, the self-discharge experiments confirmed the fact that Al-6.55Zn-0.023In-0.17Si-0.028Sn and Al-5.8Zn-0.074In-0.092Bi-0.028Ti perform satisfactorily at high temperature.更多还原