金属镁在腐蚀介质中界面结构特征与负差数效应关系研究

利用扫描隧道显微镜,在微观尺度观察腐蚀界面形貌特征.发现pH=11的1 mol/L NaCl水溶液中,金属镁表面形成块状氧化物,但微观尺度上氧化膜厚度不均,阳极化后块状氧化物尺度变小,保护作用降低,导致镁金属溶解出现负差数效应.金属镁在0.5 mol/L Na2SO4 和1 mol/L NaCl两种介质中都产生负差数效应,但氧化膜结构不同,负差数效应强弱有别.     

阴离子对铝电极电化学行为的影响

采用极化曲线测定和恒电位集气研究铝在ＮａＣｌ溶液中的电化学行为，ＮａＣｌ溶液中添加入不同的阴离子后，铝的孔蚀电位和负差数效尖系数会发生改变，不同阴离子使铝的负差数效应系数变化趋势和孔蚀活电位变化趋势的不一致性说明铝电极的负差数效应现象是中间产物的低价离子在溶液中的化学反应造成的。     

碳钢表面钛酸酯及其与PVC复合修饰膜的阻抗谱特征

实验研究了未经修饰和经Ｂｍ钛酸酯修饰及钛酸酯与ＰＶＣ复合修饰的三种４５钢试样在１．０ｍｏｌ／ＬＨ２ＳＯ４和０．５ｍｏｌ／ＬＮａＣｌ溶液中的阻抗谱。根据三种不同体系的阻抗谱特征建立了相应的等效电路模型,阻抗数据解析的结果证实了复合修饰膜结构模型和等效电路模型的正确性。     

MBT、BTA和MBO对铜缓蚀性能的电化学研究

用电化学方法比较研究了２－巯基苯并恶唑（ＭＢＯ），苯并三唑（ＢＴＡ）和２－巯基苯并噻唑（ＭＢＴ）在３％ＮａＣｌ，０．１ｍｏｌ／Ｌ ＨＣｌ和０．５ｍｏｌ／Ｌ ＨＣｌ溶液中对铜的缓蚀性能，在３％ＮａＣｌ溶液中，ＭＢＯ表现出稍优于ＢＴＡ，远高于ＭＢＴ的缓蚀能力；与ＢＴＡ和ＭＢＴ相比，在０．１ｍｏｌ／Ｌ ＨＣｌ和０．５ｍｏｌ／Ｌ ＨＣｌ中，ＭＢＯ对铜的腐蚀有突出的缓蚀效果。     

304钢焊缝环境断裂行为的定量研究

采用Ａ００１，Ａ１３２和Ａ３０２三种焊条以及（６００，８００和１０５０）℃＊６ｈ三种焊后热处理方式，研究了３０４钢不同焊缝的环境断裂行为，试验是用悬臂梁曲试样在室温０．５ｍｏｌ／ＬＮａＣｌ＋２．５ｍｏｌ／ＬＨ２ＳＯ４溶液中进行的。测定了各种焊缝的ｄａ／ｄｔ－Ｋ１曲线，并作了浸蚀试验，腐蚀电化学试验和断口分析，结果表明：焊缝的ＫＩＳＣＣ为３０－３８ＭＰａｍ＾１／２，按Ａ００２，Ａ３０２和Ａ１３２顺序     

Fe—Mn─Al合金的腐蚀性能与钝化膜的研究

应用阳极极化及ＡＥＳ／ＸＰＳ技术,研究了Ｆｅ－３０．８Ｍｎ－８．２Ａｌ奥氏体合金在ｐＨ值为－０．８至１５．３的水溶液中的腐蚀性能,并与Ｆｅ－３０Ｍｎ合金、低碳钢、９％Ｎｉ低温钢及１Ｃｒ１３不锈钢进行对比。在所测试的水溶液中,该合金的腐蚀抗力优于低碳钢和Ｆｅ－３０Ｍｎ合金,与９％Ｎｉ钢相当,但不及１Ｃｒ１３不锈钢。Ｆｅ－３０．８Ｍｎ－８．２Ａｌ合金在１ｍｏｌ／ＬＮａ２ＳＯ个中形成的钝化膜的最表层可能为氢氧化物,而膜的主体由Ｆｅ２Ｏ３、Ｍｎ２Ｏ３及Ａｌ２Ｏ３组成。     

TiAl基合金高温氧化动力学分析

关于ｉＡｌ的高温氧化问题，国内外已有广泛报道［１，２］，但缺乏对氧化产物的系统分析．本文从氧化物生成热力学角度讨论了二元ＴｉＡｌ及三元ＴｉＡｌ－Ｃｒ合金氧化产物的生成趋势，旨在为ＴｉＡｌ氧化层构造研究提供理论基础．１ＴｉＡｌ氧化物的热力学计算 二元ＴｉＡｌ在９７３Ｋ以上高温氧化时，生成两种稳定的氧化物［３］：Ｒ－ＴｉＯ２和α－Ａｌ２Ｏ３。由于ＴｉＯ２与Ａｌ２Ｏ３的生成自由能相近［４］，在原子比约为 １：１的 ＴｉＡｌ基合金中，将几乎同时生成两种氧化物，故不能形成单一致密的Ａｌ２Ｏ３保护层． 式中：气…     

ZL101A合金熔炼新工艺

ＺＬ１０１Ａ合金熔炼新工艺山东平阴铝厂谷兰成表１新工艺与传统工艺比较工艺类别原料投料顺序精炼处理新工艺０．１０～０．２０％Ａｌ－Ｔｉ合金锭（电解）结晶硅（Ｓｉ－１）金属镁（Ｍｇ－１）Ａｌ－Ｔｉ→Ｓｉ→Ａｌ－Ｔｉ→ＭｇＣＣｌ４０．５ｋｇ／ｔＡｌ７２０...     

闪锌矿中铜,铅,锌,镉的示波极谱法测定

采用一次溶解和分解试样导数极谱法测定闪放中铜、铅、锌、镉。在１．２ｍｏｌ／ｌＨＣｌ介质中测定铜、镉；在１ｍｏｌ／ｌＮＨ３－ＮＨ４Ｃｌ介质铜、锌，所得结果均在允差范围内。实践证明，对闪放中铜、铅、锌、镉的测定快速、含量适应范围宽。     

恒电位──恒电流瞬态响应技术研究钝化膜多层结构Ⅲ．氯化钠溶液中2205和316L不锈钢钝化膜稳定性的研究

采用恒电位－恒电流（Ｐ－Ｇ）瞬态响应技术研究了２２０５和３１６Ｌ不锈钢在０．５和１．０ｍｏｌ／ＬＮａＣｌ溶液中钝化膜的结构和稳定性．研究结果证实，体系的钝化膜均具有多层结构．讨论了氯离子在钝化膜生长和破坏过程中的作用．并提出可能的作用模式和破坏机制．由Ｐ－Ｇ响应曲线计算得到的各特征参数随极化电位的变化关系表明，２２０５双相钢在ＮａＣｌ介质中的耐蚀性明显高于３１６Ｌ不锈钢．另外，初步探讨了２２０５钢的组织结构与钝化膜稳定性的关系．     

Corrosion of magnesium and its alloys

Any detailed study of the corrosion of magnesium and its alloys in aqueous environment, must consider the three important aspects: galvanic corrosion reaction between magnesium and another metal, microgalvanic corrosion reaction between magnesium and the secondary phases or impurity grains, and the negative difference effect (NDE). In this paper, we propose a mathematical model to describe microgalvanic corrosion. We also discuss the NDE based on Tafel type kinetics and explain the NDE behavior in a consistent manner.     

Corrosion and corrosion testing of magnesium alloys

The corrosion behaviour of magnesium alloys is not substantially comparable to other metals, such as iron, nickel and copper. It is always accompanied by hydrogen evolution. More hydrogen is evolved at a more positive potential or a higher anodic current density. The ‘strange’ hydrogen evolution behaviour is a common phenomenon for magnesium alloys and it is called negative difference effect (NDE). The NDE continues to receive considerable discussion. Furthermore, the corrosion behaviour of magnesium alloys depends mainly on the pH value of the surrounding electrolyte. Voluminous reaction products, formed in neutral electrolytes, lead to a diffusion‐controlled dissolution on the surface of the underlying magnesium alloy. Therefore, influences from structure and alloying are suppressed very strongly. In alkaline environments, passivation occurs as a result of the formation of a hydroxide layer on the magnesium surface. Therefore, differences in the corrosion behaviour between the alloys are hardly detectable. Measurable effects can only be detected using very ‘aggressive’ corrosion conditions. Present methods do not adequately take into account the specific character of the corrosion of magnesium alloys. It can be better characterized using a rotating disc electrode for electrochemical measurements, which enables model defined flow conditions on the surface. Furthermore, the application of electrochemical noise offers the possibility of a simple and sensitive assessment of the corrosion susceptibility of magnesium alloys. Due to the high sensitivity of this measurement procedure, it is also possible to carry out examinations under more practical conditions.     

A new theory for the negative difference effect in magnesium corrosion

An unusual feature known as the negative difference effect (NDE) can be observed in magnesium when recording corrosion current density–potential curves. More hydrogen is evolved at a more positive potential which does not occur in conventional metals. Several models have been proposed in the literature in order to explain the phenomenon of NDE. They succeed in explaining some effects, and fail to deal with others. A new model, which explains the NDE by two electron consuming processes, is presented in this paper. By potentiostatic investigations of magnesium in a chloride electrolyte, measurements of hydrogen evolution and chemical analysis of the electrolyte the new model was experimentally verified.     

灰铸铁电渣重熔过程石墨球化现象的研究

实验证明,采用高Ｓｉ含量铸铁自耗电极和含稀土氧化物的ＣａＦ２基熔渣,在直流反极性电渣重熔条件下,可制得球墨铸铁,铸铁中石墨球化现象是铁水经电化学变质处理的结果,熔渣中Ｍｇ１Ｃｅ阳离子在渣－金界面阴极区被还原进入铁水熔池,起到球化剂的作用,提高阳极区自耗电极中的Ｓｉ含量,可以抑制渣中Ｆｅ阳离子的形成,有助于上述电池化学还原反应的进行,这对建立新的冶金工艺技术有一定意义。     

溶液中添加In~(3+)对铝电极负差数效应的影响

通过动电位极化、恒电位集气方法研究对纯铝在0.5mol/LNaCl溶液中的电化学行为,添加In3+后,使铝的活化电位负移,并且降低铝的负差数效应系数,提出铝溶解的动力学机制.探讨了In3+使铝电极在中性介质中抑制负差数效应的原因     

铝基牺牲阳极的溶解过程和负差异效应

用旋转环一盘电极、电子探针和形貌分析等手段研究了铝基牺牲阳极的溶解过程及其负差异效应。结果表明,铝基牺牲阳极的溶解是从第二相组织边界处引发,从而破坏表面膜而活化。阳极溶解过程中的自腐蚀(表现为析氢)是负差异效应的主要原因,它随外加电流而线性增大。铝基牺牲阳极的负差异效应系数为12.8%。     

Electrochemical discharging performance of 3D porous magnesium electrode in organic electrolyte

A novel type of porous magnesium electrode with a stable 3D copper foam as current collectors for the organic magnesium-air battery was prepared by both amperostatic and pulsed electrodeposition of magnesium on copper foam substrates in an electrolyte of 1 mol/L EtMgBr/THF solution, respectively. Optimal parameters of the pulsed electrodeposition were obtained using a bending cathode at the right angle. The surface morphology of the porous electrode was investigated by SEM, and the discharging performance of the porous magnesium electrode was detected by the chronoamperometric measurement. The electrochemical stability of 3D copper foam current collectors was examined by cyclic voltammetry, SEM and ICP-OES analyses. The results show that the rate capability of the porous magnesium electrode with a stable 3D copper foam as a current collector is better than that of the planar magnesium electrode, and the rate capability of the porous magnesium electrode prepared by the pulsed electrodeposition is superior to that of the porous magnesium electrode prepared by the amperostatic electrodeposition. The 3D structure of copper foam current collectors of the porous magnesium electrode could keep stable during the discharging process.     

Correlation of non-destructive measurements with structural degradation in stainless steel pyrolysis tubes for ethylene cracking

A commercial NDE technique was investigated to monitor structural degradation in stainless steel tubes used for ethylene cracking. In this study, data derived from a non-destructive magnetic measurement technique were compared to magnetic permeability measurements on sample sections taken from ethylene cracking tubes. These data in turn were correlated to microstructural and chemical changes occurring in the tubes after various operational conditions. Detailed microstructure and phase analysis on the oxide layer, Cr-denuded zones and oxide phases formed were carried out using Optical, Scanning Electron Microscopy and X-ray diffraction techniques. The microstructural data showed that the Cr-denuded zone, the oxide layer thickness and the spinel phase formation all increased with operational time. These data could be directly correlated to an increase in magnetic permeability and to the NDE effective thickness measurements. Excellent agreement between these two techniques was found, which indicate that magnetic Mike measurement technique can be used to track metal degradation in the ethylene cracking pyrolysis tubes.     

硅烷偶联剂在镁电极固封中的作用

采用浸涂工艺,用W-78和A-1200硅烷偶联剂对金属镁进行表面处理,然后固封制备成镁电极。对比分析了有和无硅烷偶联剂处理的镁电极的电化学行为。研究表明,两种硅烷偶联剂都可以改善镁电极的性能,显著提高了测试结果的重现性,其中A-1200效果更好。讨论了硅烷偶联剂W-78和A-1200的作用机理。     

稀土对盐浴防氧化脱碳的作用

本文就稀土对盐浴防氧化脱碳的作用进行了研究，结果表明，稀土对盐浴的校正作用具有良好的速效性和持效性，沉淀造渣能力强，可以防止酸性氧化物对工件和电极的浸蚀，是一种综合性能较好的盐浴校正剂。