Influence of Mg and Ti on the microstructure and electrochemical performance of aluminum alloy sacrificial anodes

The experiments focused on the influence of magnesium and titanium as additional alloying elements on the microstructure and electro-chemical behavior of Al-Zn-In sacrificial anodes. The electrochemical behavior of the aluminum sacrificial anode with 3 wt.% sodium chloride solution was studied by electrochemical impedance spectroscopy (EIS) tests. It was found that a microstructure with few precipitates and refined grains could be achieved by adding 1 wt.% Mg and 0.05 wt.% Ti to the Al-Zn-In alloy,resulting...

Sacrificial Anode Stability and Polarization Potential Variation in a Ternary Al-xZn-xMg Alloy in a Seawater-Marine Environment

In this paper, the effects of zinc （Zn） and magnesium （Mg） addition on the performance of an aluminum-based sacrificial anode in seawater were investigated using a potential measurement method. Anodic efficiency, protection efficiency, and polarized potential were the parameters used. The percentages of Zn and Mg in the anodes were varied from 2% to 8% Zn and 1% to 4% Mg. The alloys produced were tested as sacrificial anodes for the protection of mild steel in seawater at room temperature. Current efficiency as high as 88.36% was obtained in alloys containing 6% Zn and 1% Mg. The polarization potentials obtained for the coupled （steel/Al-based alloys） are as given in the Pourbaix diagrams, with steel lying within the immunity region/cathodic region and the sacrificial anodes within the anodic region. The protection offered by the sacrificial anodes to the steel after the 7th and 8th week was measured and protection efficiency values as high as 99.66% and 99.47% were achieved for the A1-6%Zn-l%Mg cast anode. The microstructures of the cast anodes comprise of intermetallic structures of hexagonal Mg3Zn2 and body-centered cubic A12Mg3Zn3. These are probably responsible for the breakdown of the passive alumina film, thus enhancing the anode efficiency.

Optimization of Manganese and Magnesium Contents in As-cast Aluminum-Zinc-Indium Alloy as Sacrificial Anode

In this study, effects of manganese and magnesium content on the electrochemical properties of Al-Zn-ln sacrificial anode were studied in 0.5 mol/L NaCl solution （pH=5）. The aluminum base alloy with different amounts of Mn and Mg were melted at 750℃, then casted at molds at 25℃. Corrosion experiments were mounted to determine the optimal effect of Mn and Mg on the efficiencies of the aluminum alloy anodes. The corroded and unexposed sample surfaces were subjected to microstructure characterization by optical and scanning electron microscopy. AI-Zn-ln alloy doped with 0%, 0.01%, 0.05%.0.2% and 0.3% by weights of Mn and 0%, 0.5%, 1.0%, 1.5%, 2.0%, 2.5% and 3.0% by weights of Mg were prepared to determine the effect of Mn and Mg on anode efficiency in the environment. The different microstructures of the evolved AI- Zn-ln-Mg-Mn alloy were correlated with the anode efficiencies. The Al-5.0%Zn-2.0%Mg-0.15%Mn-0.02%ln gave the best anode efficiency （about 83%）. The microstructures of the corroded surface of the optimized alloy revealed decreased distribution of the pockets of localized attacks which are characteristics of pitting （or crevice） corrosion.

EIS studies the effect of Zinc to Al-Zn alloy used for cathodic protection in 3% NaCl solution

Electrochemical impendence spectroscopy （EIS） is applied to investigate the dissolution behavior of Al-Zn alloys in 3% NaCl solution at different polarization potentials. A new reaction model is proposed, and the activation mechanism of zinc in Al-Zn alloys is achieved. There are three intermediates in the dissolution process： Znad^＋, Znad^2＋ and Alad^＋, ,of which only Zni can activate Al-Zn alloys. Most Znnd^＋ is produced by β-phase,and the alloys with 2. 3% - 3. 8% （wt） Zn dissolve rapidly. The Al-Zn alloys of heart-shaped EIS are active in 3% NaCl solution, thus EIS characteristic can be used to distinguish the activa-tion of Al-Zn alloys.

Influence of yttrium addition on properties of Mg-based sacrificial anode

To improve lower current efficiency of Mg-based sacrificial anode,a Mg-based sacrificial anode material with yttrium addition was investigated.Its electrochemical properties were evaluated by the galvanostatic method,and its microstructure and constitution were characterized by metallurgical microscope and X-ray diffraction.The results showed that,the addition of yttrium refined dentrite grains,maximized current efficiency,and minimized potential of magnesium sacrificial anode.When 0.1% yttrium was doped,the anode showed the highest current efficiency,62.5%,which improved its current efficiency by 14%.

应用油井环境的新型牺牲阳极研发

热采井井下温度较高且环境介质较为恶劣,常规配方的铝基牺牲阳极在该条件下性能较差,需要开发适用于井下高温腐蚀环境的新型牺牲阳极。本文在Al-Zn-In系列典型成分牺牲阳极材料的基础上,优化引入其它金属元素设计出适用于高温油井环境下的牺牲阳极材料,在80℃油井采出液中对所研制的阳极材料进行了恒电流测试、极化曲线等电化学性能测试,通过对比分析开路电位、工作电位、电容量、电流效率、表面腐蚀形貌等指标,筛选出一种综合性能最优的井下耐高温铝合金牺牲阳极。

水库闸门用阳极电极腐蚀性能研究

针对水库闸门长期处于水环境下易受水腐蚀的问题,开发了一种能够保护水库闸门防止腐蚀的牺牲阳极镁合金材料。通过铸态、固溶态和时效态Mg17.5Gd2.5Zn0.7Zr合金腐蚀试验测量,铸态、固溶态和时效态合金的腐蚀速率分别为0.896,3.318,3.689 mm/年。根据不同的水环境,结合合金的腐蚀速率,可以选择合适的材料作为防护水库闸门的牺牲阳极,从而提升水库闸门的使用寿命。

牺牲阳极材料的研究、应用及展望

综述了常用的镁基、锌基、铝基、复合牺牲阳极等牺牲阳极材料的性能特点;介绍了合金元素?杂质元素对阳极性能的影响;讨论了各种牺牲阳极材料的使用环境和填包料的组成及作用;展望了牺牲阳极材料的一些新发展和应用前景。

牺牲阳极材料的研究现状

综述了牺牲阳极材料的研究现状和目前常用的铝基、锌基和镁基等三种牺牲阳极材料的基本化学成分和性能特点,分析了合金元素的作用,并对牺牲阳极的一些新发展和应用情况作了介绍。

不同稀土含量的铝合金牺牲阳极的显微组织研究

浇铸了４种不同ＲＥ含量的Ａｌ－Ｚｎ－Ｉｎ－Ｓｎ－Ｍｇ合金牺牲阳极．利用金相显微镜、扫描电镜（ＳＥＭ）和能谱分析，确定了４种合金的晶粒尺寸、偏析相数量及其成分．结果表明：随着ＲＥ含量的增加，铝合金的晶粒变小，偏析相的数量先增加后减少；偏析相主要为晶界析出物和弥散相；ＲＥ含量不同时，晶界析出物不同；细化阳极晶粒最佳ＲＥ含量０．５％，０．３％ＲＥ时阳极偏析相数量最多．

铝基牺牲阳极材料的研究与开发

根据国内外研究情况,阐明了开发铝基牺牲阳极材料的基本思路是通过促进表面活化,改变其阳极极化性能,获得满足使用要求的牺牲阳极材料。同时,分析了铝基牺牲阳极从纯铝、一元铝基、二元铝基和多元铝基的开发研制过程。叙述了影响铝基阳极性能的关键因素为Sn,Bi等合金元素以及Fe,Si等杂质元素和组织结构等。最后,阐述了铝阳极材料的发展方向是特殊环境下应用的开发。

微量锑和锡对铝基牺牲阳极材料性能的影响

熔炼了添加合金元素Sb和Sn的5种Al2Zn2In系牺牲阳极材料,采用恒电流方法测试了其电化学性能,采用金相显微镜、扫描电镜和能谱分析分别观察和分析了阳极材料的显微组织和组成。结果表明:Sb具有细化晶粒的作用,但晶界存在较多偏析相,电流效率偏低;与Sb相比较,Sn也具有细化晶粒的作用,电流效率有所提高,晶界偏析相较少,但阳极的表面腐蚀溶解不均匀;Sn和Sb的协同作用在于能有效地抑制Si的偏析,显著提高阳极的电流效率,使得阳极表面具有良好的腐蚀溶解性。

铝合金牺牲阳极金相组织与电化学性能关系研究

用恒电流方法测定了３种Ａｌ－Ｚｎ－Ｉｎ系合金阳极的电化学性能，用金相显微镜和扫描电镜技术（ＳＥＭ），分析了３种阳极材料的金相组织．结果表明：阳极晶粒越小，电流效率越高；阳极第二相数量越少，电流效率越高，但溶解不均匀；

温度对Al-Zn-In-Sn-Mg阳极性能影响的探讨

对Al 5Zn 0 .0 5In 0 .1Sn 1Mg合金牺牲阳极进行 5 10℃× 10h的固溶处理 ,测定了未经固溶处理和经固溶处理的阳极在 2 0℃和 6 5℃ 30 g/L的溶液中的电化学性能 ,并进行交流阻抗测试 .结果表明 :温度升高 ,铝阳极电化学性能和溶解性能变差 ;固溶处理对阳极性能改善有利 ;高温下 ,铝阳极晶粒脱落和析氢自腐蚀更剧烈导致阳极电流效率下降 .

热处理对铝合金牺牲阳极电化学性能的影响

针对不同均匀化处理方式会引起合金微观组织和电化学性能变化现象,采用电子探针(EPMA)、动电位极化及恒电流极化等方法研究不同热处理(水淬、空冷、炉冷)方式对Al-Zn-In合金的微观组织和合金在3%NaCl溶液中的开路电位、工作电位、腐蚀形貌和电流效率等电化学性能的影响。结果表明:510℃,10 h的均匀化处理使晶界偏析减少,抑制析氢自腐蚀和晶粒脱落,提高电流效率,但对阳极开路电位、工作电位及溶解行为的影响并不明显,且水淬处理试样的电流效率最高。

Al-Zn-Sn-Ga阳极腐蚀过程的电化学阻抗谱

通过测定Al-Zn-Sn-Ga阳极在3.5%NaCl(质量分数)溶液中浸泡不同时间的电化学阻抗谱(EIS),研究该阳极的腐蚀发展过程和腐蚀特征。结果显示:当合金刚被浸入3.5%NaCl溶液时,EIS谱为反应电阻很大的容抗弧,表明此时合金处于钝化态;随着浸泡时间的延长,EIS谱中高频段的容抗弧明显减小且低频段出现感抗弧,合金进入点蚀期;继续延长浸泡时间,EIS谱中除高频段的容抗弧和中、低频段感抗弧外,在低频段出现另一容抗弧,合金处于点蚀扩展期;随着浸泡时间的继续增加,低频段感抗弧消失,EIS谱由两个容抗弧组成,合金达到均匀腐蚀期。因此,合金的腐蚀由钝化态开始,经点蚀期和点蚀扩展期,达到均匀腐蚀期。

Ga对Al-Zn-In合金牺牲阳极电化学性能影响

采用电化学测试技术和原子光谱、电子探针等分析技术,研究了Ga对Al-Zn-In合金牺牲阳极电化学性能的影响,分析了Ga、In等元素在合金中的分布形态和在铝合金活性溶解过程中的作用.结果表明,在3%的NaCl溶液中Al-4%Zn-0.022%In-0.015%Ga牺牲阳极工作电位为-1039mV,电流效率为96.3%.随着Al-Zn-In-Ga阳极中Ga的增加,阳极工作电位负移、电流效率下降,孔蚀愈加严重.电子探针分析发现,在Al-4%Zn-0.022%In-0.015%Ga阳极中Ga均匀地固溶于合金中,而In在阳极表面产生局部富集.Al-Zn-In-Ga阳极由于In3+的活化作用,破坏了表面钝化膜,使电极电位负移,从而激活了Ga3+的活性,使得Ga3+、In3+、Zn2+等产生共同沉积,维持了阳极活性溶解.

Ga含量对Al-Ga牺牲阳极电化学性能的影响

设计并熔炼了不同Ga含量的Al-Ga二元合金牺牲阳极材料,采用恒电流方法研究了Al-Ga牺牲阳极在海水中的电化学性能及Ga含量对Al-Ga牺牲阳极电化学性能的影响,并利用XRD分析了腐蚀产物以及Al-Ga牺牲阳极材料的晶格参数.结果表明,随Ga含量的增加,阳极开路电位和工作电位均负移,电流效率降低;Ga以固溶形式存在于铝基体中.

添加元素对铝基牺牲阳极的影响

用电化学测试系统和XJP-6A金相显微镜、扫描电镜和能谱分析,研究添加元素RE,Cd,Sn,Mg等在Al-Zn-In系铝基牺牲阳极溶解过程中的作用以及合金微观组织结构对牺牲阳极性能的影响。研究结果表明,Al-Zn-In系牺牲阳极在人造海水中电化学性能良好。镁对含RE铝基牺牲阳极性能有较大改善。随RE含量增加,铝合金晶粒变小,偏析相数量先增加后减少。偏析相主要为晶界析出物和弥散相,RE含量不同时,晶界析出物量不同,细化阳极晶粒最佳RE含量为0.5%,0.3%RE时阳极偏析相数量最多。

铝合金牺牲阳极材料的研究进展

论述了铝合金牺牲阳极材料的发展历程,阐述了适用于不用环境的铝合金牺牲阳极研发情况,综述了铝合金牺牲阳极的几种活化溶解理论,对影响阳极电化学性能的因素进行了探讨,分析了铝合金牺牲阳极材料技术目前存在的问题,并展望了铝合金牺牲阳极未来的发展方向。常规海水环境的牺牲阳极材料已发展得较为成熟,特殊工况环境的牺牲阳极尚有待进一步开发和完善。