镍电解阴极过程中添加剂的作用及其在线监控

研究了镍电解阴极过程中硼酸、胶、润湿剂的影响与作用,提出镍电解阴极过程中添加剂在线监控的新方法。结果表明:通过阴极过电位的在线监控可得出在不同电解条件时,添加剂最佳量的控制,从而在复杂镍电解过程中显著提高析出阴极镍的质量和光洁度,使零号镍生产的稳定性提高5%,平均电流效率提高1%。     

熔盐电解法制备铝锂中间合金

研究在LiCl-LiF-Li2CO3纯锂盐体系中下沉式铝液阴极槽结构电解生成铝锂中间合金的工艺过程,尤其是以Li2CO3为原料代替LiCl的电解过程.采用熔盐电解监控仪测量电解过程中的反电动势、槽电压、电流等工艺参数及电解波形图,通过电位控制法调节Li2CO3的加料周期,同时根据得到的合金产品中的锂含量探讨影响电流效率的因素.结果表明,反电动势随电流密度增加而增大,加入2%的Li2CO3可使反电动势降低0.5 V;通过控制电位法测得加料周期为15 min;在680℃、电流密度为0.62 A/cm2的条件下持续电解3 h,最终制得了锂含量高达7.93%的铝锂合金,电流效率可达74.1%.     

复合型LaNi5／Ni—S合金镀层在碱液中的析氢反应

通过熔盐电解结合水溶液电沉积方法获得了复合型LaNi5/Ni-S合金镀层.Na3AlF6-La2O3(质量比为92:8)体系中的熔盐电解实验表明,由于阴极Ni具有较强的阴极去极化能力,即使在远未达到La析出电位的条件下,仍可获得LaNi5储氢合金层.电化学测试表明,该复合阴极材料具有较高的电化学活性,在80℃、30%NaOH溶液中,当阴极电流密度为150 mA·cm-2时,其析氢过电位仅为75 mV.循环伏安及开路电位测试表明,LaNi5合金层在电解过程中可吸收一定量的氢,在电解槽出现断电或逆电流情况下这些吸收氢可发生放电过程,避免阴极材料溶出,从而为该析氢阴极提供电化学保护.     

电解液质量对锌电积过程的影响及其在线控制

阐述了湿法炼锌过程中,由于电解液中杂质的波动对锌电积过程主要技术经济指标产生的严重影响,分析了金属杂质、骨胶浓度与阴极过电位和电流效率的关系,提出了利用阴极过电位对锌电积最佳添加剂浓度及新液质量的控制方法。根据电极过程动力学原理,发明了电解液质量在线监控的方法和装置,以实现自动控制添加剂的加入。实际应用结果表明,这种在线控制方法与传统的经验控制法相比,可使每吨析出锌电耗减少５０．９６～１０１．９２ｋＷｈ,电流效率提高２个百分点,锌电积车间酸雾浓度降低３０％～５０％,提高特高品级电锌产量,大大降低剥锌劳动强度。     

Hydrogen evolution reaction on the composite LaNi5/Ni-S alloy film in alkaline medium

通过熔盐电解结合水溶液电沉积方法获得了复合型LaNi5/Ni-S合金镀层. Na3AlF6-La2O3 (质量比为92 : 8) 体系中的熔盐电解实验表明, 由于阴极Ni具有较强的阴极去极化能力, 即使在远未达到La析出电位的 条件下, 仍可获得LaNi$_{5}$储氢合金层. 电化学测试表明, 该复合阴极材料具有较高的电化学活性, 在80 ℃、 30%NaOH溶液中, 当阴极电流密度为150 mA cm-2时, 其析氢过电位仅为75 mV. 循环伏安及开路电位测试表明, LaNi5合金层在电解过程中可吸收一定量的氢, 在电解槽出现断电 或逆电流情况下这些吸收氢可发生放电过程, 避免阴极材料溶出, 从而为该析氢阴极提供电化学 保护.     

阴极辊MIG铜焊裂纹控制方法

阴极辊是电解铜箔设备中电解铜箔生成载体和阴极电流传送的载体。铜套、铜环、铜堵板起导电的作用,由于铜的熔点高,焊接性较差,铜套、铜环、铜堵板、钢筒之间的焊接过程中容易产生裂纹、气孔、空洞等缺陷,以致导电效果不良,影响阴极辊质量。文中介绍了采取铜焊缝表面处理、加温温度控制、焊接工艺参数等3个措施来控制裂纹的产生,提高铜焊质量,使铜焊一次合格率从60%提高到100%。     

液态铝阴极法制备铝钙中间合金

在CaCl2-CaF2体系中,以CaO为电解原料,采用液态铝阴极法生产铝钙中间合金。采用熔盐电解监控仪测量电解过程中的反电动势、槽电压、电流等工艺参数及电解波形图,通过电位控制法调节CaO的加料周期,同时根据所得合金产品中的钙含量(质量分数)探讨影响电流效率的因素。结果表明:反电动势随电流密度增加而增大,通过控制电位法测得加料周期为30 min;在740℃、电流为7 A的条件下,电解1 h可制取钙含量为11.6%的铝钙合金,电流效率可达67.3%。     

铜电解中添加剂的检测

对于铜和酸浓度相对稳定的铜电解系统来说,添加剂是影响阴极铜质量的主要因素。只有正确测定电解液中添加剂的浓度,其用量才可能随电流密度的变化作出适当调整,也才能使其在电解液和阴极表面上保持最佳的浓度,保证在比较高的电流密度下得到致密的结晶阴极铜。     

铜电解中添加剂的检测

对于铜和酸浓度相对稳定的铜电解系统来说,添加剂是影响阴极铜质量的主要因素。只有正确测定电解液中添加剂的浓度,其用量才可能随电流密度的变化作出适当调整,也才能使其在电解液和阴极表面上保持最佳的浓度,保证在比较高的电流密度下得到致密的结晶阴极铜。     

过热度和电流密度对半石墨质阴极低温电解膨胀性能的影响

采用改进型阴极电解膨胀率测试仪,研究低温电解质[K_3AlF_6/Na_3AlF_6]-AlF_3-Al_2O_3中电流密度和过热度对半石墨质阴极电解膨胀性能的影响,并对阴极的电解膨胀性能进行数值化表征.结果表明:金属K和Na由表及里渗透进入阴极内部;随着过热度和电流密度的增大,阴极电解膨胀率均呈增大趋势;当电解质过热度由10 ℃升高至50 ℃时,阴极电解膨胀率由1.41%增大至2.10%;随电流密度的增大阴极电解膨胀率呈现出不同的增幅;当电流密度小于0.4 A/cm~2或大于0.7 A/cm~2时,阴极电解膨胀率均明显增大;而当电流密度在0.4 A/cm~2到0.7 A/cm~2之间变化时,阴极电解膨胀率相对恒定、增幅最小;数学模型中引入的参数可用于表征阴极的电解膨胀及低温电解质中阴极抗K和Na渗透性能;低温电解时,降低熔体过热度、选择合适的阴极电流密度均可减小金属K和Na对阴极的破坏作用.     

氨络合物体系中杂质Zn~(2+)对电沉积镍的影响

通过霍尔槽试验研究氨络合物体系中杂质Zn~(2+)对镍电沉积的影响,采用电化学工作站测试不同Zn~(2+)浓度时的循环伏安曲线、稳态极化曲线及电流时间暂态曲线.结果表明:杂质Zn~(2+)的含量为0.1 g/L时,在小于2.78 A/dm的电流密度范围内可正常沉积出金属镍;杂质Zn~(2+)含量大于0.5 g/L时,在较大的电流密度范围内均无法正常沉积出金属镍;过电位小于640 mV时,Zn~(2+)的存在不影响阴极反应的传递系数,且不改变阴极反应机理;当过电位大于640 mV,且杂质Zn~(2+)的浓度大于0.5 g/L时,阴极反应的传递系数减小,阴极反应机理发生改变;杂质Zn~(2+)浓度大于0.5 g/L时,严重影响镍电结晶过程的成核速率,这是其抑制金属镍电沉积的主要原因.因此,采用镍氨络合物体系电积金属镍,应控制杂质Zn~(2+)的含量小于0.1 g/L.     

Polarization behaviour of copper whisker crystal in acidic cupric sulphate solution

The polarization behaviour of copper whisker crystal was investigated in acidic cupric sulphate solution by a potential sweep method limited to 120 mV of overpotential. When the overpotential limit was above 130 mV, sweep experiments gave scattered results due to random nucleation. The apparent exchange current density on a whisker was around 10^?5 A/cm², three orders of magnitude less than that on a polycrystalline copper.The exchange current density is increased by the twisting of a whisker: it is proportional to the twist angle. The defect dependency of the exchange current is discussed in relation to a surface-diffusion model.Polarization curves at low overpotentials show asymmetry of the cathodic and anodic branch. The surface defects introduced by twisting appear to be four times as effective for anodic dissolution as for cathodic deposition.     

Electrochemical studies on La-Co alloy film in acetamide-urea-NaBr melt system

1INTRODUCTIONThe magnetic rare earth elements bring signif-icant changes to the magnetic material industry dueto their excellent magnetic and magneto-opticalproperties[1].Since La and Co are rich elements innature,in addition to their relatively cheap prices,it would be very prospective to prepare magneticfunctional materials using La-Co alloy.Comparedwith traditional techniques of spray and vacuumspattering or sputtering,electrodeposition is aneconomical method to develop alloy fil m du…     

Electrochemical properties of La0.8Sr0.2FeO3-δbased composite cathode for intermediate temperature SOFC

La0.8Sr0.2FeO3-δ is a new kind of cathode material for intermediate SOFC, but its electrochemical activity is relative poor for the lanthanum gallate based solid oxide fuel cell. In this paper, a novel composite cathode of La0.8Sr0.2FeO3-δ/La0.9 Sr0.1Ga0.8Mg0.2O3-δ was prepared on the LSGM electrolyte substrate by screen-printing method. The results of cathodic polarization measurements show that the overpotential decreases significantly when the composite cathode is used instead of the La0.8Sr0.2FeO3-δ single layer cathode. The cathodic overpotential of the composite La0.8Sr0.2FeO3-δ/La0.9Sr0.1Ga0.8 Mg0.2O3-δ cathode is 150 mV at the current density of 0.2 A·m-2 at 800 ℃, while the cathodic overpotential of the La0.8 Sr0.2 FeO3-δ single layer cathode is higher thaN260 mV at the same condition. The electrochemical impedance spectroscopy was employed to investigate the polarization resistance of the cathode. The polarization resistance of the composite cathode is 1.20 Ω·m2 in open circuit condition, while the value of the single La0.8 Sr0.2 FeO3-δ cathode is 1.235 Ω·m2.     

The Effect of Oxygen on Copper Dissolution during Cathodic Polarization

The effect of oxygen on the anomalous dissolution of copper in acidic chloride media is studied. An increase in the copper corrosion rate during cathodic polarization in the potential range from –0.4 to –0.7 V is attributed to stirring of the near-electrode layer by evolving hydrogen bubbles. An addition of surface-active tetrabutylammonium iodide shifts the overpotential of hydrogen evolution and eliminates this effect. The copper dissolution rate during cathodic polarization is shown to be directly proportional to the reduction rate of dissolved oxygen. It is shown experimentally that H₂O₂ does not affect the dissolution rate of copper during cathodic polarization. The latter fact makes it possible to assume that oxygen reduction stages, which involve hydrogen peroxide, do not affect the anomalous dissolution of copper.     

Specific effects of propargyl alcohol and propargyl chloride on an iron electrode in inorganic acids

The effect of acetylenic compounds, namely, propargyl alcohol (PA) and propargyl chloride (PC), on electrode processes occurring on Armco iron in hydrochloric, sulfuric, phosphoric, and perchloric acids was studied with the use of potentiostatic polarization. In oxygen-containing acids with hydrophilic anions, PA and PC are hydrogenated, thus decreasing the cathodic overpotential and significantly retarding iron ionization, which causes pitting at a free corrosion potential. More hydrophobic Cl⁻ anions increase the cathodic overpotential and hinder the hydrogenation process. Propargyl chloride inhibits electrode reactions and iron corrosion more effectively than does less hydrophobic PA.     

Organic Additives: A Source of Hydrogen in Copper Cathodes

Increased quality requirements have been placed on electrolytically-refined copper cathodes for use as metal feed in the continuous casting and rolling processes. The presence of hydrogen in the copper is believed to be the most significant single impurity factor affecting the quality of the cast copper product. Hydrogen has a synergistic effect with grain boundary impurities which results in excessive cracking during hot rolling. This paper covers the effect of organic additives, mainly glue and thiourea, on the cathodic overpotential, and the relationship between the overpotential and the organic additive entrapment and the hydrogen content in the copper cathode.     

Effects of additives on zinc electrodeposition from alkaline zincate solution

The effects of additives on the surface and cross-sectional morphologies of zinc deposits on iron substrate from alkaline zincate solution were characterized by scanning electron microscope (SEM). The cathodic reaction mechanisms under various concentrations of additives were investigated using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) techniques. It is found that with increasing the additive A content in the bath solution, the nucleation overpotential (NOP) value is obviously increased and the inhibition effect is strengthened. This may be mainly due to the adsorption of additive A on the cathodic electrode surface, which can cover the active sites and block the discharge reduction. The results of EIS analysis indicate that the rate-determining step of zinc electrodeposition process is changed from mixed control step into electrochemical reduction step in the presence of additive A. However, any quantity of additive B has little effect on the NOP value and the inhibition effect is not obvious. Furthermore, addition of additive A and additive B at the same time displays the strongest inhibition effect and shows a strong synergism because of their co-adsorption on the cathodic electrode surface.     

负极集流体表面处理方法及对电池性能的影响

在高能扣式碱性锌锰电池负极集流体表面制备出一种性能良好的高氢过电位材料Zn-In合金.采用线性扫描阴极极化曲线、X射线衍射(XRD)、扫描电镜(SEM)、能谱分析(EDS)、交流阻抗(EIS)及电池气胀高度检测等方法研究Zn-In合金材料的性质、各组分的含量以及对电池性能的影响.结果表明:该Zn-In合金材料显著提高了集流体析氢过电位,从而有效地抑制电池气胀, 改善电池性能,同时降低生产成本,且对环境友好,因此用于代替In电沉积具有广阔的应用前景.