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Al-Zn-In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.     

Mg-Mn高电位牺牲阳极的腐蚀行为

采用金属型铸造了3种成分的梯形高电位Mg-Mn牺牲阳极.通过模拟土壤环境中[饱和CaSO4-Mg(OH)2溶液]的恒电流腐蚀试验,研究了Mg-Mn牺牲阳极的腐蚀行为.结果表明,Mg-Mn牺牲阳极中杂质元素存在较大的溶质偏析和明显的晶粒尺寸差异,导致距离模具表面不同距离处的电流效率不同.杂质元素在晶界上不均匀分布,使Mg-Mn阳极产生晶间腐蚀,第二相粒子不均匀程度越大,未腐蚀部分机械剥落越严重,从而加大阳极的质量损失,降低了阳极的电流效率.腐蚀形貌观察发现,当Mg阳极表面呈现出条状的蚀坑时,机械剥落现象严重,腐蚀很不均匀,电流效率较低,仅为41％;Mg阳极的表面蚀孔孔径越细小,分布越均匀,电流效率越高.     

深海低温高压条件下铝合金牺牲阳极电化学性能研究

牺牲阳极的阴极保护法是海洋环境下控制钢结构腐蚀有效的方法,电流效率与电位稳定性是鉴别牺牲阳极电化学性能优劣的重要指标。本文使用了电流效率测试和表面形貌观察等方法,测试分析了三种不同成分铝合金牺牲阳极在低温高压海水环境中的电化学性能,结果表明:三种成分的铝合金牺牲阳极都具有较高的电流效率,其中成分3的铝合金牺牲阳极表面溶解最均匀,呈现均匀溶解形貌,未见明显蚀坑和晶间腐蚀现象。     

Al-Zn-In系牺牲阳极低温电化学性能研究

研究了三种Al-Zn-In牺牲阳极在低温下的电化学性能,其中Al-Zn-In-Cd牺牲阳极在低温时电流效率为84%左右,阳极溶解呈非均匀状,腐蚀产物不脱落,不适用于低温环境;Al-Zn-In-Mg-Ti牺牲阳极在低温时电流效率为90%左右,表面呈均匀状溶解,腐蚀产物脱落,具有较好的电化学性能.     

合金元素Ga对Al-Zn-Bi系阳极材料腐蚀机理的影响

采用恒电流法测定了添加Ga元素前后的Al-Zn-Bi系合金在人造海水中的开路电位、工作电位和电流效率,观察了该试验过程后合金的表面腐蚀形貌;利用极化曲线和电化学阻抗谱研究了该阳极合金在3.5%NaCl溶液中腐蚀过程的演变规律。结果表明：Ga能使Al-Zn-Bi系合金开路电位负移,工作电位稳定,电流效率升高,腐蚀形貌更加均匀;Ga可均匀固溶于铝合金中,并与回沉积的阳离子形成Ga基汞齐,使得阳极合金的活化控制步骤由第二相粒子优先溶解-脱落机理转变为金属阳离子的溶解-再沉积机理,促进阳极合金的均匀溶解,从而提高其综合电化学性能;等效电路RL（Cs（CpRp）（Q1Rd1）（LRa））和RL（Cs（CpRp）（Q1Rd1）（LRa）（Q2Rd2））能较好地表征两种合金的腐蚀行为和活化机理。     

析出相对铝基牺牲阳极组织及电化学性能的影响

基于化学成分调控制备了两种不同的Al-Zn-In系阳极。在表征了析出相成分、分布的基础上,研究了析出相对阳极电化学性能的影响。采用扫描电镜(SEM)、能谱仪(EDS)表征析出相、腐蚀形貌及腐蚀产物。在污水储罐水质环境中进行了电化学性能测试,温度为室温(20℃)。结果表明:Al-Zn-In-Mg-Ti的第二相为富In相,呈细小颗粒状分布,Al-Zn-In-Mg-Sn的第二相为InSn2相,呈球状分布;在两种阳极的晶界处都形成了Al4Fe第二相,呈层片状分布。Al-ZnIn-Mg-Ti、Al-Zn-In-Mg-Sn的电流效率分别为65%、74%。宏观上均为典型的局部腐蚀形貌,微观上均发生了以析出相溶解为主的晶间腐蚀。Al-Zn-In-Mg-Ti点蚀严重,有径向腐蚀发展趋势,以富In相的优先溶解机理为主;Al-Zn-In-Mg-Sn较均匀,纵向腐蚀较为明显,以InSn2相的溶解-再沉积机理为主。     

Mg和RE合金化对Al-Zn-Bi合金阳极组织和电化学性能的影响

针对Al-Zn-Bi合金,分别单独及复合添加Mg、RE元素进行微合金化,利用金相、扫描电镜及X射线能谱等分析了该合金添加不同元素前后的微观组织特征;采用恒电流法测定了该系列合金在人造海水中的开路电位、工作电位和电流效率,利用极化曲线和电化学阻抗谱,分析了微合金化对Al-Zn-Bi阳极材料电化学性能的影响。结果表明：单独添加Mg、RE可以细化晶粒、改善偏析相的组成和分布,将电流效率提高15.93%和4.12%;二者复合添加虽电流效率稍有降低,但可促使基体均匀溶解,减小腐蚀电流密度,从而有效提高其综合性能。     

铝镁基牺牲阳极的电化学性能

向以Al-Mg为基体的合金中添加Zn、In、Mn以及微量Ti、B元素,研究了合金成分及组织形态对电化学性能的影响。结果表明,Mg元素含量高的合金组织中,呈现粗大第二相,在介质中溶解不均匀;当加入Mn、Ti、B等元素使组织形态变化后,阳极溶解性能及电流效率有较大改善。     

Sn对Mg合金阳极材料组织及电化学性能的影响(英文)

采用金相显微镜、X射线衍射(XRD)、扫描电镜(SEM)、结合能谱( EDS )研究了Sn对镁阳极材料显微组织、相结构、表面形貌及成分分布的影响;并通过恒电流法、动电位极化法、排水集气法等研究了该镁合金的腐蚀行为和电性能。结果表明:合金元素Sn、Pb的加入可以抑制棒状β-Mg17Al12相沿晶界析出,合金晶粒尺寸均匀,随着Sn含量的增大,颗粒相Mg2Sn增多;均匀化处理使大部分β-Mg17Al12相溶解,而残留Mg2Sn和Mg2Pb未溶相;Sn的加入可以提高镁合金自腐蚀电位,降低析氢率,当Sn含量为2wt%时,镁合金阳极的放电电压和电流效率最大。由于镁合金的"负差数效应"使得析氢率随电流密度的增大而增大,当电流密度为10mA/cm2时,电流效率最高,可达88%;腐蚀产物主要成分为Mg(OH)2、SnO2及MgSnO3,且疏松,易脱落,使镁合金阳极的工作电极电位负而且稳定,可促进电池反应深入进行。     

合金元素Mg对含RE铝阳极组织与性能的影响

采用恒电流方法,测定了Al-5Zn-0.05In-0.1Sn-0.3RE和Al-5Zn-0.05In-0.1Sn-Mg-0.3RE两种铝合金牺牲阳极材料电流效率、利用金相显微镜、扫描电镜和能谱分析,研究了它们的金相组织。结果表明：镁对含RE铝阳极性能有较大改善,镁的添加改变了铝合金晶界偏析相的组成;晶界析出物Mg相减轻了铝阳极的晶界腐蚀和晶粒脱落。     

稀土元素和固溶处理对Al阳极电化学性能的影响

对Al-Zn-In-Sn-Mg和Al-Zn-In-Sn-Mg-RE 2种Al合金 阳极进行固溶处理，测定了经固溶处理和未经固溶处理的阳极在20℃和65℃的3%NaCl溶液中 的电化学性能 .结果表明,高温下Al阳极电流效率普遍下降，腐蚀变得不均匀;添加RE的固 溶处理阳极在65℃时性能优良；固溶处理可改善Al阳极在高温介质中的性能.讨论了RE及固 溶处理对高温介质中Al阳极性能的影响.     

Effects of precipitates on the electrochemical performance of Al sacrificial anode

The influence of precipitates on the electrochemical performance of Al–Zn–In–Mg–Ti–Si sacrificial anode was investigated by the TEM observation and electrochemical measurements. The results indicate that the shape and size of precipitates in the alloys has great impact on the electrochemical performance. The anodes with rod-like precipitates are easily corroded along grain boundaries, resulting in the low current efficiency caused by serious grain loss. In comparison, the anodes with spherical or discal precipitates have high current efficiency and even corrosion morphology. The precipitates with a size of about 400 nm are conducive to improve the electrochemical performance of anodes.     

Novel corrosion experiments using the wire beam electrode. (IV) Studying localised anodic dissolution of aluminium

An electrochemically integrated multi-electrode array namely the wire beam electrode (WBE) has been applied in novel experiments to study the anodic dissolution behaviour of aluminium (AA1100), which was exposed to corrosive media with and without the presence of corrosion inhibitor potassium dichromate. The objective of this work is to demonstrate the applicability of the WBE for investigating corrosion processes under anodic polarisation. Anodic current measurements and mapping have been made, for the first time, with the WBE surface being anodically polarised. Pitting potential as well as anodic dissolution profile has been successfully determined by mapping anodic dissolution currents over the anodically polarised WBE surface. The pitting potential determined using the WBE method was found to correlate well with that determined using the conventional pitting scan method; and the anodic dissolution profile determined using the WBE method was found to correlate with maps obtained using the scanning reference electrode technique (SRET). Potassium dichromate was found to significantly affect the pitting potential, anodic dissolution profile and pitting initiation characteristics of aluminium. Two mechanisms of localised corrosion initiation have been identified. For WBE surface under free corrosion or low anodic polarisation conditions, the initiation of localised corrosion was found to be due to the disappearance of minor anodes, which lead to accelerated dissolution of a few major anodes. For WBE surface under large anodic polarisation, the initiation of localised corrosion was found to be due to the formation of active new anodic sites. This work suggests that the WBE method is useful for understanding the electrochemical behaviour of localised anodic processes, and their dependence on externally controllable variables.     

Investigations on the Electro-Deposition of Silver,with Special Reference to the use of Sodium Cyanide

The results of an investigation on the deposition of tin-zinc alloys, ranging in composition from 92/8 to 28/72, are discussed, and instructions are given for the deposition of the alloy containing 78% of tin, which appears to be the most serviceable. The electrolyte contains sodium stannate, zinc cyanide, sodium hydroxide, and sodium cyanide and is operated at 70°C., using tin-zinc alloy anodes of approximately the same composition as the deposit. A feature of the process is polarisation of the anodes so as to ensure dissolution of the tin as stannate. The influence of changes in the composition of the electrolyte, in cathode current density, and in temperature on the composition of the deposit have been examined and measurements have been made of the effect of alteration in the working conditions on anode and cathode efficiency. Chemical methods for the analytical control of the plating bath and alloy deposit are given.     

合金元素对铝基牺牲阳极性能的影响

通过合金化方法,在Al-Zn-In三元牺牲阳极中依次添加Mg、Ti、Ga、Mn、Sn等元素,炼制不同成分的铝合金牺牲阳极。采用电化学性能测试、极化曲线测量及扫描电子显微镜分析等手段分析了合金元素对铝合金牺牲阳极性能的影响。结果表明,随着添加元素种类的增加,牺牲阳极电化学性能提高。在Al-Zn-In三元阳极中加入Mg和Ti,阳极溶解形貌更加均匀;加入Ga与Sn后,阳极的开路电位与工作电位负移;加入Mn后阳极的电流效率提高。     

Revealing the effect of aluminum content on the electrochemical performance of magnesium anodes for aqueous batteries

Al is one of the principal alloying elements for Mg anodes. In this study, a series of Mg–Al alloys has been evaluated as anode materials for optimizing the Al addition amount in Mg anodes with the intention of improving the discharge performance in aqueous batteries. The effect of Al content on the discharge potential and corrosion resistance of the Mg anode has been investigated through microstructure characterization, electrochemical measurements in a half-cell, discharge morphology analysis, and Mg–water battery tests. The results show that the Mg–1Al alloy possesses a larger corrosion resistance during discharge, with significant increase of the anode utilization efficiency at 1 and 5 mA/cm² compared with pure Mg. However, a further increase of Al content does not continuously improve the discharge performance of the Mg anode with the decline of utilization efficiency due to the influence of the precipitated phase. This study contributes to a better understanding about the effect of Al on anodic dissolution and corrosion kinetics of the Mg anode.     

The Rate-Determining Stage in the Anodic Dissolution of Metals

An experimental study has been made, using the potentiostat technique, of the limiting current densities of metal dissolution in electrolytic polishing solutions. The limiting current densities show the features expected for diffusion currents, and the effect of the addition of the metal dissolution product to the electrolyte indicates that it is the diffusion of this substance away from the anode which determines the overall rate of the electrode reaction. Electrolytic polishing does not occur until the limiting current density has been reached, and experiments with composite anodes show that the diffusion current densities at peaks in the surface are much higher than at cavities. These observations are interpreted by a simple diffusion layer treatment of the kinetics of the anode reaction, and their bearing upon the mechanism of electrolytic polishing is reviewed. Some practical recommendations for electrolytic polishing are made.     

Throwing Power of Plating Solutions with Particular Reference to Certain Zinc Plating Solutions

The electrodeposition of speculum from solutions containing sodium stannate, sodium cuprocyanide, free sodium hydroxide and free sodium cyanide, with and without addition of sodium carbonate, using separately controlled tin and copper anodes, has been investigated and conditions for obtaining satisfactory deposits of constant composition have been worked out. A study has been made of the influence of variation in the concentrations of tin, copper, free hydroxide and free cyanide in the solution, and of alteration in temperature and in current density on the composition of the deposit and efficiency of deposition. Anode conditions have been examined and information obtained on the factors on which the efficiency of dissolution of the tin and copper depends. The ageing of speculum solutions is explained and consideration is given to the addition of sodium carbonate to the bath as a means of increasing its stability. A preliminary survey of the potentialities of baths containing potassium salts in place of the corresponding sodium salts has been made.

Analytical methods for determining the composition of the electrolyte and deposit have been put forward.     

杂质Fe对A1-Zn-In牺牲阳极性能的影响

炼制Fe杂质含量不同的6种Al-Zn-In阳极,采用恒电流方去评价了其电化学性能,并通过扫描电镜观察其溶解的微观形貌,探讨了Fe杂质含量对阳极电化学性能的影响规律与机制.结果表明,随着Fe杂质含量的升高,Al-Zn-In阳极的电流效率呈先增加后降低趋势,原因足少量的Fe可增加阳极的活化点,而过量的Fe则作为阴极相引发电偶腐蚀使得阳极呈局部腐蚀溶解.     

Ten‐year results of galvanic sacrificial anodes in steel reinforced concrete

Zinc sacrificial anodes have been included in patch repairs to steel reinforced concrete structural elements suffering from corrosion since the mid‐1990s. A number of these anode‐containing repairs have been monitored with time. One of the first monitored sites was of a locally repaired cross beam of a bridge structure in Leicester, UK, which has now completed 10 years since its original repair and anode installation. This paper reviews the performance of the anodes installed at the Leicester site in terms of anode current output and steel reinforcement polarisation and corrosion rate over the period. It also presents results of analysis of recovered anodes exposed for 10 years which still show electrolyte continuity, uniform consumption of the zinc and coherent encasing mortar. The knowledge gained from the 10 year results has enabled the development of new, higher current output anodes, which are now trialled in this and other sites.