短路还原法提取铁的研究

采用氧离子导体氧化锆管与还原剂碳、含有电活性物质FeO的熔渣组成电化学体系,利用原电池短路方法从氧化物熔渣中电化学还原得到了无碳金属．实验电池组成为：石墨,[O]Fe—C（aaturated）｜ZrO2（MgO）｜Cu（1）＋（FeO）（alag）,钼丝．利用电化学分析仪,通过测定外电路电流研究了渣中FeO含量、温度以及外电路电阻对熔渣中FeO电化学还原的影响．结果表明：在实验条件下,温度越高,渣中FeO含量越高,外电路电阻越小,熔渣电化学还原就越快．实际终还原率达95％以上．提出了可控氧流冶金中的一种还原方法,发展了可控氧流冶金理论．     

含FeO熔渣的起泡过程及起泡参数间关系分析

对ＣａＯ－ＳｉＯ２－Ａｌ２Ｏ３－ＦｅＯ熔渣在石墨还原过程中的起泡行为的分析表明，熔渣的起泡率受渣中气体的产生速度及熔渣的起泡指数影响；熔渣的起泡指数随渣中气泡直径的增大而减小；随熔渣碱度的减小，泡沫渣的平均寿命延长，泡末化愈稳定。     

利用电化学方法测定高温银液中氧的扩散系数

采用圆柱体状氧化锆基固体电解质原电池:(+)Pt|air|ZrO_2(MgO)[O]_(Ag(l))|Ir(-),利用恒电压法测定了1473-1773 K银液中氧的扩散系数.通过外加恒电压后测定的电池外电路总电流,获得随时间变化的穿过固体电解质的氧离子电流,进而计算得到银液中氧的扩散系数.在假定符合Arrhenius公式的基础上,实验结果经最小二乘法处理确定的在1473—1773 K扩散系数与温度的关系为:D_O=(1.11±0.04)×10~(-3)exp((-25573±1718)/RT).实验测得的银液中氧的扩散系数值与基于前人低温测定结果外推到本实验温度下的值比较接近.利用该公式计算得到1773 K下银液中氧的扩散系数D_O=(1.96±0.28)×10~(-4)cm~2/s.     

NaCl-KCl共熔盐中Zn2+的电化学还原机理(英文)

为了开发高效、环境友好型冶金粉尘中锌回收技术,提出一种将选择性氯化和熔盐电解相结合的工艺。首先,通过热力学论证上述处理工艺的理论可行性。然后,采用多种暂态电化学测试方法研究973K时NaCl-KCl共熔盐中Zn²⁺在钨电极上的电化学行为。结果表明,Zn²⁺的还原过程是一步转移2个电子的反应,起始还原电位为-0.74 V(vs Ag/AgCl);且为受扩散控制的准可逆过程,计算得到Zn²⁺的扩散系数为10^-5cm²/s数量级。最后,在NaCl-KCl-ZnCl₂熔盐中于-1.6 V (vs Ag/AgCl)进行恒电位电解,电解9.5 h、后获得银白色类球状金属颗粒,经分析证实为金属Zn。本研究表明,在NaCl-KCl共熔盐中直接电解ZnCl₂提取金属锌是可行的,为冶金粉尘中锌的高效回收提供了有益的理论参考。     

Ti（Ⅳ）在氯化物熔体中的电化学还原

研究了ＫＣｌＬｉＣｌ熔体中Ｔｉ（Ⅳ）的电化学还原机理和钛沉积及沉积动力学,计算了各还原步骤传递的电子数。结果表明,Ｔｉ（Ⅳ）的电化学还原为三步电荷传递反应,即：Ｔｉ４＋→Ｔｉ３＋→Ｔｉ２＋→Ｔｉ。Ｔｉ（Ⅳ）的电化学还原速度由离子扩散速度来控制。在一定熔体组成及温度下,沉积物的性质依赖于电解时间及电解电位。在ＫＣｌＬｉＣｌ熔体中阴极电位为５００ｍＶ（相对钼电极）,电解时间为４ｈ时,可获得粘附性能好的钛沉积物,并观察到沉积物为细小结晶堆积起来的多孔体。钛的纯度可达９９．９％。     

Pure metal extraction from molten oxide slag by short-circuit galvanic cell

The oxygen-ion-permeable membrane galvanic short-circuit method has been developed, in which pure metal was directly extracted from the molten oxide slag, and no external voltage is applied. The galvanic cell employed in the experiment was as follows: graphite rod|[O]_(Fe C saturation)[ZrO_2(MgO)|(FeO)_(slag))|Fe rod. The reduction current in the galvanic cell consisted of an external short-circuit current and an interior short-circuit current in the oxygen-ion-permeable membrane. The real-time variation of external circuit reduction ratio of the molten slag could be obtained from the curve of the external circuit current to the time.     

LiF—NaF—K2TiF6熔盐中Ti（Ⅳ）的电化学还原

用循环伏安法和卷积技术研究了ＬｉＦ－ＮａＦ低共熔体中，以Ｋ２ＴｉＦ６形式加入的Ｔｉ（Ⅳ）在铂电极上钥极还原机理，计算了各还原步骤所传递的电子数。结果表明：Ｔｉ（Ⅳ）的电化学还原机理为耦联均相歧化反应的三步骤电荷传递反应。     

LiF─NaF─K2TiF6熔盐中Ti(Ⅳ)的电化学还原

用循环伏安法和卷积技术研究了LiF-NaF低共熔体中,以K2TiF6形式加入的Ti(Ⅳ)在铂电极上阴极还原机理,计算了各还原步骤所传递的电子数。结果表明,Ti(Ⅳ)的电化学还原机理为耦联均相歧化反应的三步骤电荷传递反应。     

MgO-CaO-SiO2焊接熔渣离子活度的热力学分析

针对焊接熔渣分子理论及离子理论存在的局限,基于冶金界近年来提出的熔渣共存理论,结合MgO-CaO-SiO2高温三元相图确定的结构单元,利用质量平衡原理建立了MgO-CaO-SiO2三元熔渣离子活度热力学计算模型,并借助于Matlab计算工具进行数值求解.计算结果表明,该模型可同时兼顾熔渣的分子理论和离子理论,离子活度随碱度的变化与碱度理论及直流焊接冶金电化学实验结果一致,在焊接化学冶金定量研究方面显示出良好的应用前景.     

Effect of electrolysis voltage on electrochemical reduction of titanium oxide to titanium in molten calcium chloride

The electrochemical reduction of solid TiO2 directly to solid metal is a ptomising alternative to the current Kroll process. The present work is aimed at studying the effect of electrolysis voltage on the rate of electrochemical reduction. The products of electrochemical reduction of TiO2 and Ti2O were examined using the scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques. The results show that Ti2O was reduced to low valent titanium oxide at 1.5 -1.7 V, which was the result of ionization of oxygen. TiO2 and Ti2O were reduced to titanium metal at 2.1-3.1 V, which was the co-action of ionization of oxygen and calciothermic reduction. The oxygen content decreased rapidly with voltage increasing from 2.1 to 2.6 V, while it changed little from 2.6 to 3.1 V. The optimized cell voltage was 2.6-3.1 V.     

Coating titanium on carbon steel by in-situ electrochemical reduction of solid TiO2 layer

Ti coating on A3 steel was successfully prepared by direct electrochemical reduction of high-velocity oxy-fuel (HVOF) thermally sprayed and room-temperature dip-coating titanium dioxide coating on A3 steel in molten CaCl₂ at 850 °C. The interfacial microstructure and mutual diffusion between coating and steel substrate were investigated using scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) spectroscopy. The results show that the precursory TiO₂ coating prepared by HVOF has closer contact and better adhesion with the A3 steel substrate. After electrolysis, all of the electro-generated Ti coatings show intact contact with the substrates, regardless of the original contact situation between TiO₂ layer and the steel substrate in the precursors. The inter-diffusion between the iron substrate and the reduced titanium takes place at the interface. The results demonstrate the possibility of the surface electrochemical metallurgy (SECM) is a promising surface engineering and additive manufacturing method.     

Improving plasma-sprayed yttria-stabilized zirconia coatings for solid oxide fuel cell electrolytes

Using a D-optimal design of experiments, the influences of feedstock powder and plasma gases on deposition efficiency, gas tightness, and the electrochemical behavior of vacuum plasma-sprayed yttria-stabilized zirconia for solid oxide fuel cell electrolytes were examined. In-flight particle temperature and velocity, measured by online particle diagnostics, were correlated with plasma and deposit properties. Electrochemical testing of cells was performed to determine the influence of gas tightness and microstructure of electrolyte deposit on cell behavior. This article was originally published inBuilding on 100 Years of Success: Proceedings of the 2006 International Thermal Spray Conference (Seattle, WA), May 15–18, 2006, B.R. Marple, M.M. Hyland, Y.-Ch. Lau, R.S. Lima, and J. Voyer, Ed., ASM International, Materials Park, OH, 2006.