纯镁牺牲阳极的熔铸及其电化学性能和腐蚀形貌

以"硅热还原法"生产的纯镁为原料,采用金属型铸造工艺浇铸了纯镁牺牲阳极,考察了纯镁牺牲阳极的杂质含量在熔铸过程中的变化趋势及其电化学性能和腐蚀形貌。结果表明:纯镁牺牲阳极杂质含量仍然保持较低水平,其电化学性能满足ASTM 843-2003的要求,电流效率最大值达到了54%;纯镁牺牲阳极的开路电位取决于α-Mg基体的电位,α-Mg基体固溶元素较少,电位较负,开路电位较高,其最大值达到了-1.74V(vs SCE)。     

海水溶解氧量对铂钽复合阳极电化学性能的影响

为研究溶解氧量对铂钽复合阳极电化学行为的影响,通过测量阳极的开路电位、动电位极化曲线以及施加电位分别为0.90,1.15,1.35,1.55 V时的电化学阻抗谱,研究了铂钽复合阳极在不同溶解氧量海水中的电化学行为.结果表明,阳极在溶解氧量分别为0,4,8 mg/L时对应的开路电位分别为0.276,0.296,0.372 V,表明阳极的电化学性能有所降低;在施加电位为0.90,1.15 V时,溶解氧在阳极钝化、过钝化过程中对钝化膜的形成以及溶解具有显著的作用,而随着外加电压的增大,在1.35,1.55 V时,阳极二次钝化过程中溶解氧的影响作用减弱.     

船用铜质海水冷却设备的牺牲阳极阴极保护

为提高船用铜质海水冷却设备的腐蚀安全性,采用极化曲线、腐蚀仿真计算和样机腐蚀试验方法综合研究了船用铜质海水冷却设备牺牲阳极的阴极保护行为。结果表明:海水环境下铁合金牺牲阳极与铜合金开路电位差值合理,在提供充分的阴极保护驱动电位的前提下,能够有效降低阳极材料的溶解速率,比锌合金阳极更适合于铜合金的阴极保护;Fe-Mn-Cr合金阳极可以在保证铜合金阴极保护效果的基础上,有效提高自身服役寿命,可靠性优于现役的Zn-Al-Cd合金阳极,具有良好的工程应用价值。     

Al-Zn-Sn-Bi系合金添加Ga,Ce后牺牲阳极的电化学性能

为了提高Al-Zn-Sn-Bi合金牺牲阳极的电化学性能,通过不同方式添加Ga和稀土元素Ce,熔炼了Al-Zn-Sn-Bi(1号),Al-Zn-Sn-Bi-Ce(2号),Al-Zn-Sn-Bi-Ga(3号),Al-Zn-Sn-Bi-Ga-Ce(4号)4种阳极合金,分析了4种阳极合金在人造海水中的开路电位、电流效率、腐蚀均匀性、腐蚀产物黏附状态等电化学性能,并通过阳极合金的微观形貌及其在3.5%NaCl溶液中的极化曲线、电化学阻抗谱分析了添加Ga,Ce对阳极合金电化学性能的作用机制。结果表明:同时添加Ga和Ce的Al-Zn-Sn-Ga-Bi-Ce电流效率达96.7%,综合电化学性能明显改善;Al-Zn-Sn-Bi和Al-Zn-Sn-Bi-Ce合金阳极的活化机理可用Rs[CcoxRcox(QR1)(L1Rad1)(L2Rad2)]等效电路表示,Al-Zn-Sn-Bi-Ga和Al-Zn-Sn-Bi-Ga-Ce合金阳极的活化可用Rs[QR1(C1Rw1)(C2Rw2)(LRad)]等效电路表示。     

AZ镁合金空气电池阳极在NaCl溶液中的电化学性能

采用动电位极化扫描、恒电流放电、化学浸泡法研究不同Al含量AZ31、AZ61、AZ913种AZ镁合金阳极的放电性能和腐蚀电化学行为。结果表明,3种镁合金阳极随Al含量的增加,腐蚀电位发生正移。合金的腐蚀电流密度呈先减小后增大的趋势;25℃的3.5%(质量分数)NaCl溶液中,3种合金阳极的放电电位随放电电流密度的增大而正移。30 mA/cm~2放电电流密度下,AZ61合金具有较负的平均放电电位,随时间延长平均放电电位负移且逐渐趋于平稳,表现出良好的放电性能。随Al含量的增加合金阳极自腐蚀速率有所下降,阳极利用率呈先增大后减小的趋势。3种合金阳极中,AZ61合金中形成大量点状或不连续短条状的β相,金属颗粒脱落较少,阳极利用率较高。     

Mn元素对AP65阳极组织和性能的影响

采用熔炼铸造法制备AP65合金阳极材料,采用恒电流扫描法、动电位极化扫描法和浸泡法研究Mn含量对其在3.5%NaCl中的电化学性能和自腐蚀性能的影响,采用光学显微镜、扫描电镜和X射线衍射仪对其显微组织和腐蚀形貌进行观察和检测。结果表明Mn元素的加入,能粗化AP65阳极的铸态组织,使AP65阳极的腐蚀电位正移,腐蚀电流密度减小,耐蚀性能得到显著提高;使AP65阳极平均电极电位负移,当Mn含量为0.3%时,AP65阳极平均电极电位最负,达到-1.528VSCE。     

铝空气电池Al-Zn-In-Mg-Ga-Mn合金阳极的电化学性能

研究了铝空气电池的Al-Zn-In-Mg-Ga-Mn合金阳极在2 mol/L NaCl和4 mol/L KOH电解液中的自腐蚀行为和电化学性能。结果表明,在2 mol/L的NaCl和4 mol/L的KOH溶液中,Al-Zn-In-Mg-Ga-Mn合金阳极比纯Al阳极的腐蚀电位(E_corr)分别负移了0.041和0.018 V,自腐蚀速率分别降低了0.2146和15.1 mg·cm^-2·h^-1,使金属阳极的电化学活性得以提高,自腐蚀行为受到了抑制。在2 mol/L的NaCl电解液中,合金阳极的放电容量峰值达到2608.96 Ah·kg^-1,比纯Al阳极提高了55.59%;能量密度最高为1742.61 Wh·kg^-1,比纯Al阳极提高了274.58%,阳极效率为87.55%。在4 mol/L的KOH电解液中,合金阳极的放电容量最高为1605.15 Ah·kg^-1,比纯Al阳极提高了131.27%;能量密度最高为1404.83 Wh·kg^-1     

铝酸盐及添加剂对铝阳极电化学性能的影响

为了扩大铝阳极的应用范围,采用添加剂来降低其腐蚀速度,同时活化铝阳极.用塔菲尔曲线、线性扫描伏安法、恒电流放电等方法,研究了在4 mol/L KOH溶液中,NaAlO2及添加剂NaF对铝(99.999%)阳极电化学性能的影响.结果表明:NaAlO2对铝阳极有害,NaAlO2的浓度不要超过3 mol/L;但添加50 mmol/L NaF在3.5 mol/L NaAlO2 4 mol/L KOH中,则铝的腐蚀电流密度由23.7 mA/cm2降低到20.8 mA/cm2,电极电位由-0.75 V负移到-1.50 V,开路电位由-1.64 V负移到-1.68 V,电位滞后时间缩短,基本上恢复到铝在4 mol/L KOH溶液中的电化学性能.     

铝基Pb-WC-CeO_2脉冲复合镀层阳极材料的电催化性能

目前,电镀锌工业常用的Ca、Co系铅基合金阳极成本高、性能不佳,不能广泛应用,将WC和稀土CeO2掺杂入铅及其合金可望解决上述问题。采用脉冲电镀在铝基体上制备了Pb-WC-CeO2复合镀层用作阳极材料。考察了正向脉冲参数(平均电流密度Jm,占空比r及正向电流时间ton)及镀液温度对复合镀层在模拟锌电解液中用作惰性阳极时的电催化性能,从节能高效角度优选出了脉冲工艺:Jm=0.12 A/cm2,r=20%,ton=200 ms,温度50℃。在此工艺条件下获得了具有较低析氧电位、较好电催化活性的阳极材料。     

舰船铜合金海水管路铁基牺牲阳极阴极保护研究

采用电化学测试、电偶腐蚀试验和腐蚀仿真计算方法综合研究了铁基牺牲阳极在海水环境下对铜合金管路提供阴极保护的效果。研究结果表明,海水环境下铁合金牺牲阳极与铜合金开路电位差值合理,在提供充分的阴极保护驱动电位的前提下,能够有效降低阳极材料的溶解速率,比锌合金阳极更适合于铜合金的阴极保护;铁基牺牲阳极在铜合金管路阴极保护过程中,保护电流发散受管路尺寸影响,一般可保护10倍管径范围区域。研究成果对于提高海水环境下铜合金管路的腐蚀安全性具有参考意义,具有良好的工程应用价值。     

牺牲阳极在舰船阴极保护中的应用和进展

分别论述了铝合金牺牲阳极、锌合金牺牲阳极、铁合金牺牲阳极的研究和发展过程,总结了各种阳极的研发现状、研发热点和相应的阳极产品研发成果,指出了针对特殊环境和细分领域的各种阳极,是阳极新材料未来发展的主要方向。对于铝合金牺牲阳极,介绍了常规铝合金牺牲阳极和包括海水环境低驱动电位阳极、油污海水低驱动电位牺牲阳极、适用于干湿交替环境的阳极和适用于高温环境中的阳极等在内的针对特殊环境和特殊材料的铝合金牺牲阳极在舰船阴极保护领域的应用,总结了船舶用铝合金牺牲阳极的研究进展;对于锌合金牺牲阳极,主要介绍了锌合金牺牲阳极的发展历史、研究现状和相应的阳极产品;对于铁合金牺牲阳极,主要总结了铁合金牺牲阳极的研究现状和在舰船上的实际应用。     

典型牺牲阳极在脱硫催化液中的性能研究

通过恒电流实验法测试了6种常用牺牲阳极材料在不同温度的硫回收催化剂溶液中的电化学性能。结果表明,高硅铸铁牺牲阳极开路电位、工作电位稳定,表面溶解均匀,在较高温度下电流效率最高,尤其是在60℃时达到89.7%,综合性能最好;溶解的产物Fe^2+不会对原有催化剂造成影响,是一种比较理想的硫磺回收装置保护用牺牲阳极材料。     

Biocorrosion properties and blood and cell compatibility of pure iron as a biodegradable biomaterial

Biocorrosion properties and blood- and cell compatibility of pure iron were studied in comparison with 316L stainless steel and Mg–Mn–Zn magnesium alloy to reveal the possibility of pure iron as a biodegradable biomaterial. Both electrochemical and weight loss tests showed that pure iron showed a relatively high corrosion rate at the first several days and then decreased to a low level during the following immersion due to the formation of phosphates on the surface. However, the corrosion of pure iron did not cause significant increase in pH value to the solution. In comparison with 316L and Mg–Mn–Zn alloy, the pure iron exhibited biodegradable property in a moderate corrosion rate. Pure iron possessed similar dynamic blood clotting time, prothrombin time and plasma recalcification time to 316L and Mg–Mn–Zn alloy, but a lower hemolysis ratio and a significant lower number density of adhered platelets. MTT results revealed that the extract except the one with 25% 24 h extract actually displayed toxicity to cells and the toxicity increased with the increasing of the iron ion concentration and the incubation time. It was thought there should be an iron ion concentration threshold in the effect of iron ion on the cell toxicity.     

块体纳米晶工业纯铁在盐酸溶液中的电化学腐蚀行为

通过静态失重试验,动电位极化曲线,电化学阻抗谱(EIS)实验,研究了块体纳米工业纯铁(BNIPI)和粗晶工业纯铁棒(CGPIR)在室温1mol/l盐酸溶液中的腐蚀行为.结果表明,BNIPI与CGPIR相比,开路腐蚀电位Ecorr正向移动114mV,平均腐蚀速度和腐蚀电流Icorr变小,极化电阻Rp增大为1.58倍.BNIPI抗盐酸的腐蚀能力与CGPIR相比,不但没有下降,相反有所增强.使用扫描电子显微镜(SEM)对静态腐蚀失重试样的形貌进行了观察,显示BNIPI上几乎没有点蚀坑出现.     

ECAP加工与热处理对工业纯铁点蚀行为的影响

通过多道次等通道转角挤压(ECAP)和退火热处理,制备不同组织结构状态的超细晶工业纯铁,采用透射电镜观察微观组织结构特征,并用电化学极化和阻抗谱技术表征超细晶纯铁在含氯离子的钝化介质中点蚀行为。结果表明:随着ECAP加工道次增加,低道次形成的高位错密度板条状结构转变为低位错密度等轴晶;ECAP样退火热处理后,位错减少、大角度晶界增加。ECAP加工道次对纯铁自钝化性能影响不大,开路电位和极化电阻变化均较小;耐点蚀性能与加工道次有关,点蚀电位随加工道次先下降后升高;退火处理后自钝化性能和耐蚀性提高,开路电位、极化电阻和点蚀电位均明显增大。     

Mechanical,electrochemical and magnetic behaviour of duplex stainless steel for biomedical applications

Mechanical, electrochemical and magnetic properties of duplex stainless steel were analysed to evaluate its use as biomaterial, comparing the results with those obtained for austenitic stainless steel. Yield and ultimate tensile strengths are almost twice in duplex stainless steel, being the values 870?MPa and 564?MPa, respectively. The electrochemical test revealed that this material has lower susceptibility to localised corrosion because of its greater passive range, 1?V from the open circuit potential, while the austenitic stainless steel exhibited a passive region of 0.370?V. Both steels behave as soft magnetic materials, however, duplex stainless steel has higher magnetic saturation and remanence, while austenitic stainless steel is more prone to heating when exposed to a magnetic field.     

低温青藏高原土壤中镁合金阳极的电化学性能

为评价低温土壤对镁合金阳极电化学性能的影响,通过极化曲线、交流阻抗和电流效率实验方法,研究了4种镁合金阳极在-4℃和4℃的模拟低温青藏高原土壤中的电化学性能.研究表明:镁合金中加入Mn、Al和Zn元素可与杂质元素形成阴极作用较弱的金属间化合物,降低了镁合金的自溶解倾向,提高了电流效率;镁合金阳极在低温青藏高原土壤中呈活性溶解状态,溶解活性和反应活性由强到弱顺序为MGAZ63B镁合金、MGAZ31B镁合金、MGM1C镁合金和高纯镁;4种镁合金阳极中MGAZ63B的电流效率最高,-4℃和4℃时分别为54.39%和61.77%;4℃土壤中氧的扩散速率比-4℃时高,故镁合金阳极在青藏高原土壤中4℃时溶解活性和电流效率均优于-4℃时.     

Active Stainless Steel/SnO2-CeO2 Anodes for Pollutants Oxidation Prepared by Thermal Decomposition

Stainless steel plates were successfully coated with SnO₂-CeO₂ films (SS/SnO₂-CeO₂) by brush coating with a solution of stannous chloride and cerium trichloride followed by thermal decomposition. It is proven that the properties of SnO₂ films can be evidently improved by Ce doping, and 600°C is the optimum temperature to prepare SS/SnO₂-CeO₂ anodes. The physicochemical and electrochemical properties as well as the electrocatalytic activity of the electrodes were investigated. It is found that the novel electrodes have compact microstructure, high overpotential for oxygen evolution (1.60 V vs SCE), excellent electrochemical stability, relatively low cost and excellent catalytic activity for oxidizing pollutants. An industrial dye wastewater, which is hard to be purified by using conventional chemical flocculation methods, was oxidated by employing the SS/SnO₂-CeO₂ anodes, and 83.00% of color and 48.62% of chemical oxygen demand (COD) removal was achieved under the cell voltage of 5 V within only 2 min, and the electricity consumption is only 1.83 kWh for oxidizing 1 m³ of dye wastewater.     

Electrochemical study of the corrosion behavior of Ce sealing of anodized 2024 aluminum alloy

The technological process of Ce sealing of anodized LY12 (2024) alloy is introduced in this paper. The corrosion behavior of the film is studied by polarization curves and electrochemical impedance spectroscopy. The results show that the coating remains passive at the potential range from the open circuit potential (−780 mV) to −250 mV. After immersing the sample in NaCl solution for 6 days, the outer layer Ce conversion coating begins to loose its anticorrosive property. The inner Ce sealing anodized film is not corroded until 60 days immersion. Thus, the inner layer Ce sealing anodized film takes the leading role of the corrosion protection for LY12 alloy.     

Effect of povidone–iodine addition on the corrosion behavior of cp–Ti in normal saline

The effect of various concentrations of povidone–iodine (PI) on the corrosion behavior of a commercially pure titanium alloy (Ti-1) has been investigated in normal saline solution to simulate the povidone–iodine addition in an oral environment. The open circuit potential, electrochemical impedance spectroscopy and potentiodynamic polarization measurements have been used to characterize the electrochemical phenomena occurring on the alloy surface. The open circuit potential values for Ti-1 in various concentrations of PI shift considerably towards noble direction as compared to pure normal saline. In the potentiodynamic polarization curve for Ti-1 in various solutions, the cathodic current density has increased for all concentrations of PI and the anodic current density has decreased. Only the 0.1% PI concentration is able to inhibit corrosion of Ti-1 in normal saline and the other higher concentrations studied, accelerate corrosion. The EIS data for Ti-1 in normal saline and in various concentrations of PI follows a one time constant circuit, suggesting the formation of a single passive film on Ti-1 which is not altered by the addition of PI to normal saline.