Progressive degradation of noble metal coated titanium anodes in sulphuric acid and acidic copper sulphate electrolytes

Anodes having a nominal loading of 5 g/m² of 70% platinum—30% iridium alloy on a titanium substrate were employed in repetitive galvanostatic runs at 8.1–540 mA/cm² in 2 M H₂SO₄ electrolyte, with and without the addition of 0.5 M CuSO₄. The increase in anode potential with time was attributed to two causes: passivation of the noble metal surface, and oxidation of the substrate metal beneath the coating. Surface platinum loadings were monitored by an X-ray fluorescence technique, and loss rates averaged 1.30 mg/A h, independent of the operating variables of the present investigation. Surface platinum losses were attributed to a direct electrochemical dissolution process, except in the cases where complete anode degradation occurred which was accompanied by substrate attack and spalling of the noble metal coating.     

CeO2对Ti基RuO2-SnO2涂层阳极电催化性能的影响

采用热分解法制备了掺杂CeO2的Ti基RuO2-SnO2涂层阳极,通过开路电位测试、循环伏安测试以及交流阻抗测试研究了所制备涂层阳极的电催化性能,并用扫描电镜观察了涂层阳极的表面形貌。结果表明,在涂层阳极中掺杂CeO2可以提高涂层阳极的电催化活性,CeO2的最佳掺杂量为0.4(摩尔分数)。涂层阳极电催化性能提高的原因在于掺杂的CeO2可以提高涂层的有效活性表面积。     

Coating evolution with an implantable biological battery

A cathode of smooth platinum in a right endoatrial position and an anode of Domal magnesium were used to construct a hybrid bioelectric battery designed to power a pacemaker. In use the cathode is gradually covered by a coating consisting of a crystalline layer and a layer of connective tissue. This coating is responsible for the system change in the reduction process at the cathode level: the transfer from an oxygen to a hydrogen system. This system change causes a voltage drop in the bioelectric battery. This paper deals with oxygen diffusion across the tissue layer, as well as with various spectral and chemical analyses. A high level of calcium and phosphorus in the different analyses carried out seems to show that the presence of these elements is related to the coating of the cathode. The effect on the formation of the coating of the position of the cathode is also discussed.     

外加应变对航空有机涂层损伤规律的影响

借助有机涂层预应变施加方法,跟踪观察户内加速试验过程中受到外加应变的航空有机涂层表面形貌变化,利用环境扫描电子显微镜进行显微组织表征,利用电化学阻抗谱进行特定频率的阻抗模值分析,进而综合研究航空有机涂层在外加应变和热带海洋大气环境耦合作用下的损伤规律和失效模型.研究发现,外加拉应变导致有机涂层的防护性能下降,外加拉应变水平越高,有机涂层损伤越严重,防护性能下降越多.进行户内加速试验过程中,受到外加拉应变的涂层防护性能进一步下降,外加拉应变越大,下降越快.受外加拉应变的涂层防护性能下降的原因是相应的应力水平超过有机涂层材料的断裂强度,从而在涂层内部形成微裂纹,构成外界溶液到达有机涂层/合金界面的通道.受到外加压应变后,有机涂层的防护性能不发生明显变化.进行户内加速试验过程中,受到外加压应变的涂层防护性能缓慢丧失,受到外加压应变水平越高,涂层防护性能下降越缓慢.

     

Investigation of Anode Effect During the Electrolysis of Salt Melt

Anode effect is observed during the electrolysis of salt melt and has the largest significance for the electrolysis of cryolite-alumina melts. The anode effect results in a sharp increase in voltage across the electrolysis cell terminals and a reduction of current; with this a shining circle of small spark discharge appear on the boundary between electrolyte and the anode. The anode effect takes place on anodes manufactured of graphite, silicon, silicon carbide, titanium diboride, gold and platinum. The anode effect is examined in details in a book where six hypotheses considering a mechanism for the origin and proceeding of this phenomenon are presented.1 In spite of numerous investigations, the nature of the anode effect and the reasons of its origin can not be considered finally revealed.

Our studies of the anode effect were aimed at finding conditions that would enable us to control this phenomenon     

Ir-Ta氧化物涂层阳极在硫酸盐电解溶液中的电化学行为

采用测量极化曲线等电化学方法研究了钛基Ir-Ta氧化物涂层阳极在酸性硫酸盐溶液中的电化学行为。结果表明:酸性硫酸盐溶液中Ir-Ta氧化物涂层阳极上的析氧反应发生电化学极化,但超电势远低于Pb阳极和Pb-Ag阳极而电催化活性好,可以显著降低电解能耗。溶液pH和电解温度升高,Ir-Ta氧化物涂层阳极上析氧反应的超电势降低;溶液中含有不同金属离子时析氧反应的超电势略有不同,但金属离子浓度不影响其超电势。Ir-Ta氧化物涂层阳极在1 mol/L H2SO4溶液和电流密度40000A/m2的条件下的强化寿命可达55天。     

Effect of baking temperature and anode current density on anode carbon consumption

The electrolytic anode carbon consumption (CC) was studied as a function of anode baking temperature (BT) and anode current density in a closed laboratory cell, where the anode gas was absorbed and also monitored on a CO/CO₂ analyzer. The CC referred to Faraday’s law was determined from the weight loss of the anode, the carbon gasification (CG) from the amount of absorbed anode gas, and the formation of carbon dust (CD) by the difference. The CC decreased by about 9 pct per 100 °C increase in BT, and it increased with decreasing anode current density, particularly at low current densities. The CG and CD showed similar trends. The excess CG, which was attributed to the Boudouard reaction (CO₂ + C = 2CO), showed a relative decrease with increasing current density, although the overall rate of the reaction increased.     

具有微米纤维碳的硅/石墨/碳复合材料的制备及在锂离子电池中的应用

以沥青为软碳原料,商业石墨的载体材料,通过高温热解法成功合成了硅/石墨/碳复合材料,同时原位生成了微米尺度的碳纤维.该硅/石墨/碳复合材料具有诸多优点,石墨片层堆叠之间的空隙为硅的体积膨胀提供了有效的空间,沥青热解碳材料的包覆能一定程度抑制硅基材料的体积效应和提高其电子电导率,同时微米级的碳纤维能提高材料的长程导电性和结构稳定性,从而极大的改善负极材料循环性能.通过电化学测试表明,硅/石墨/碳复合材料中硅/石墨/碳复合负极材料在200 mA·g-1电流密度下具有650 mA·h·g-1的可逆容量,在200 mA·g-1电流密度下经过500圈循环后容量保持率为92.8%,每圈的容量衰减率仅为0.014%,展现了优异的循环性能.      

ELECTROLYSIS OF LIQUID FAYALITE SLAGS

Abstract

Electrolysis of liquid fayalite slags was carried out at 1250 °C using a liquid copper cathode and an inert platinum anode. At the cathode, iron precipitated with a current efficiency above 55%. The cathodic current efficiency decreased with increasing slag magnetite content. When Cu₂O was added to the slag, metallic copper was formed at the cathode with current efficiencies as high as 80%. In terms of the recovery of copper from metallurgical slags, electrolysis would be most beneficial for slags with a high dissolved copper content such as slags from direct to copper smelting.

Over time, the cell voltage decreased due to an increase in the effective surface area of the anode and also partly due to an increase in the slag conductivity due to increasing magnetite content. The increasing anode area was caused by a magnetite-rich deposit forming around the platinum wire anode.

On a effectué l’électrolyse de laitiers de fayalite liquides à 1250 °C en utilisant une cathode en cuivre liquide et une anode inerte en platine. Le fer était précipité à la cathode avec un rendement du courant au-dessus de 55%. Le rendement du courant cathodique diminuait avec une augmentation de la teneur en magnétite du laitier. Lorsqu’on ajoutait du Cu₂O au laitier, du cuivre métallique se formait à la cathode avec des rendements de courant aussi élevés que 80%. En ce qui concerne la récupération du cuivre à partir des laitiers métallurgiques, l’électrolyse serait davantage bénéfique pour des laitiers ayant une teneur élevée en cuivre dissous, comme des laitiers du traitement direct de fonte de cuivre.

Avec le temps, le voltage de la cellule diminuait à cause d’une augmentation de la superficie efficace de l’anode et aussi en partie à cause d’une augmentation de la conductivité du laitier résultant d’une augmentation de la teneur en magnétite. L’augmentation de la superficie de l’anode était causée par un dépôt riche en magnétite qui se formait autour du fil en platine de l’anode.     

The aluminization of platinum and platinum-coated IN-738

The chemistry and morphology of aluminide coatings formed on platinum and platinum-coated IN-738 have been studied. Most of the aluminide coatings evaluated were applied using the pack cementation process. For aluminized platinum a series of intermetallic Pt-Al compounds form. The stoichiometries of these compounds are essentially in agreement with those that would be predicted based upon phase diagram considerations. For aluminized, platinum-coated IN-738, the coating morphology and chemistry are highly dependent upon the thickness of the platinum layer. A relatively thick platinum layer (∼25 microns) confines the initial reaction for the aluminizing conditions used so that refractory metal elements from the substrate are excluded from the outer regions of the coating. Thinner platinum layers only partially confine the reaction and do not exclude the refractory metals from the coating. Microstructures that develop are related to the appropriate phase diagrams.     

锂离子电池正极材料表面包覆的研究进展

锂离子电池正极材料是锂离子电池发展的关键。对锂离子电池正极材料进行包覆是改善其性能的有效方法。锂钴氧和锂锰氧正极材料表面包覆后的循环性能,特别是高温下的循环性能可以得到有效的改善。对于LiFePO4来讲,表面包覆主要是解决这类正极材料导电性问题。文章综述了国内外锂离子电池材料表面包覆的研究现状,提出了作者对将来研究方向的一些看法和建议。     

电解重量法测定阳极铜中铜

先用恒电流电解重量法测定阳极铜中铜,然后通过原子吸收光谱法(AAS)测定电解残余液中铜,电感耦合等离子体原子发射光谱法(ICP-AES)测定沉积在铂阴极上的金、银等杂质元素,对电解重量法的测定结果进行修正。分别考察了电解条件、铂阴极干燥时间对分析结果的影响,结果表明,在设定电流为1.5A时电解3.0~3.5h后取出铂阴极,干燥3~5min,可以获得较好的测定结果。按照实验方法测定阳极铜中铜,结果的相对标准偏差(RSD,n=11)小于0.05%。方法用于铜合金标准物质IARM 71B中铜量的测定,测定值与认定值相一致。     

三元乙丙橡胶紫外老化表观行为及纳米防老化剂作用机制

基于荧光紫外加速老化实验,追踪三元乙丙橡胶的老化过程,研究添加纳米防老化剂对材料表观老化行为和抗老化能力的影响,并利用傅里叶红外光谱和紫外吸收光谱分析纳米防老化剂的作用机制.随着老化时间的延长,试样表面粗糙度增加,色差和失光率变大,羰基指数上升,紫外吸收率下降.傅里叶红外光谱分析显示,表面二氧化硅膜包覆抑制了纳米二氧化钛的光催化作用,延缓了三元乙丙橡胶的老化进程.添加纳米防老化剂后,试样表面孔洞密度减少,色差和失光率分别降低0.97和22.29%,羰基指数下降0.06,紫外光吸收率升高3.92%,三元乙丙橡胶的抗紫外老化能力提高.     

钛基钛锰合金阳极抗钝化机理分析

从电化学及电极表面结构方面分析了钛基钛锰合金阳极的抗钝化机理，钛基钛锰金阳极抗钝化的主要原因可归因子电极表面锰元素的存在，以及电极的特殊表面形态。     

析氧型贵金属涂层钛阳极的研究进展

贵金属涂层钛阳极是近年来发展起来的具有广阔应用前景的新型阳极,尤其在以有色金属电解为代表的电化学体系中,展示出巨大的发展潜力.文章综述了国内外析氧环境中贵金属涂层钛阳极的研究和开发方面的重要工作和进展,其中重点阐述了IrO2-Ta2O5涂层不同方法的改性研究.评述了各制备方法的优势和不足.同时,简单介绍了贵金属涂层钛阳...     

Morphology and Hardness of a Steel Surface Layer after Electric-Spark Alloying with TiN ― Ni Alloys

Features of forming a coating surface with electric-spark alloying and TiN Ni alloy electrode materials are established. Analysis of coating morphology makes it possible to draw conclusions about the discrete nature of coating structure formation. Features of the interaction of deposited material with the anode due to changes in the phase composition and electrode structure are established.     

钙熔盐电解石墨阳极破损及防护研究

通过扫描电镜和电子探针分析钙熔盐电解中破损石墨阳极的结构和杂质，探索了其破损机理。通过实验研制出适合于钙熔盐电解过程用的石墨阳极的涂层，并对涂层进行了扫描电镜分析，结果说明该涂层是致密无裂纹且附着力强，具有较好的抗氧化能力，能防止或减少石墨阳极的消耗。     

Effects of TiC composite coating on electrode degradation in microresistance welding of nickel-plated steel

Electrode degradation has been studied during series-mode microresistance welding of thin-sheet nickel-plated steel to nickel. The main focus of the study was the effects of a TiC metal matrix composite coating. The results indicated that electrode degradation was caused predominantly by material loss due to pitting (as a result of the fracturing of local bonds between the electrode tip and sheet) and also by microscopic extrusion or plastic deformation (as a result of the softening of electrode tip regions). The composite coating improved tip life by about 70 pct, mainly because the TiC particles contained in the coating discouraged local bonding between the electrodes and sheets, and probably also improved the resistance to surface extrusion. It was also found that the use of an oxide-dispersion-strengthened copper alloy (Cu-Al₂O₃) improved tip life by only about 15 pct compared to the conventional precipitation-strengthened Cu-Cr-Zr electrode alloy.     

锡含量对铅钙锡惰性阳极耐蚀性能的影响

利用线性电位扫描法(LSV)、循环伏安法(CV)和塔菲尔曲线(Tafel)对不同锡含量的铅钙锡合金阳极在铜电解沉积360h后进行电化学分析,并结合失重法测定合金的阳极腐蚀速率。结果表明,铅钙锡合金阳极的耐蚀性能随着锡含量的增加而提高。     

NiAl／BN可磨耗封严涂层摩擦磨损性能研究

利用大气等离子喷涂技术制备NiAl／BN可磨耗封严涂层,采用可模拟可磨耗封严涂层工况的高速／高温摩擦磨损试验机研究了涂层在650℃下的摩擦磨损性能,探究了涂层磨损机理。结果表明,涂层硬度对NiAl／BN封严涂层与K24镍基高温合金叶片间的摩擦系数、涂层磨损量和磨损机理均有明显影响。摩擦系数随涂层硬度增大而增大;涂层磨损量随硬度增大而减小;当硬度为35HR15y和45HR15y时,涂层磨损机理为切削、涂抹、摩擦氧化,当硬度为55HR15y时,涂层磨损机理为涂抹和摩擦氧化。