镍在低碳钢表面的扩散机理与规律

采用水溶液电沉积+高温固态扩散法成功制备了镍/低碳钢表面复合材料，研究了镍在低碳钢表面的扩散机理，利用Den Broeder法得到了不同温度下镍在低碳钢中的扩散规律。结果表明，高温固态扩散退火处理实现了镍沉积层与低碳钢的冶金结合，镍原子主要沿低碳钢晶界进行扩散，其扩散抑制了晶粒的长大。碳、硅、锰、硫、磷原子对镍原子的扩散影响较小。镍原子在低碳钢表面的固态扩散规律为D_Ni=-3.53×10^-21T⁴+1.75×10^-17T³-3.22×10^-14T²+2.60×10^-11T-7.81×10^-9。在973～1373 K温度区间固态扩散时，随着温度的升高，镍原子的平均互扩散系数呈现先上升后下降再上升的趋势；晶体结构对于镍原子的扩散影响较大，镍原子在体心立方晶体结构中的扩散速度明显大于在面心立方晶体结构中的扩散速度。     

不同工艺下镁合金MAO/GO/SA复合涂层的耐蚀性

为提高AZ91D镁合金基体的耐蚀性，采用微弧氧化、电沉积和自组装工艺在AZ91D镁合金表面制备了微弧氧化/氧化石墨烯/硬脂酸(MAO/GO/SA)复合涂层。通过SEM对复合涂层的微观组织结构进行了分析，利用电化学阻抗谱、极化曲线测试了复合涂层的耐蚀性能。结果表明，最佳电沉积电压为4 V,此时，MAO/GO复合涂层的电荷转移电阻(R_ct)为4.41×10⁵Ω·cm²,腐蚀电流密度(J_corr)为3.88×10^-7 A/cm²。醇水比为7∶3时，MAO/GO/SA复合涂层的R_ct值为3.07×10⁶Ω·cm²,J_corr为3.02×10^-8 A/cm²,达到超疏水状态，涂层耐蚀性最好。     

Ti-22Al-25Nb合金板材高温拉伸变形行为的本构模型

在1203～1283 K的温度范围内,以20 K的温度间隔对O相Ti-22Al-25Nb合金进行了等温单向拉伸试验,应变速率为2.5×10^-4、5.0×10^-4、1×10^-3、2×10^-3、4×10^-3、1×10^-2和5×10^-2 s^-1,并对不同变形温度下的试样组织进行了表征。通过实验结果,确定了本构模型的材料常数;α₂+B2/β+O三相区(1203～1243 K)和α₂+B2两相区(1243～1283 K)的拉伸变形激活能分别为845 165和412 779 J/mol。构建了Arrhenius本构模型来描述Ti-22Al-25Nb合金在不同温度下的拉伸变形行为。     

质子交换膜燃料电池不锈钢双极板表面Cr2AlC涂层的制备与耐蚀性能

采用直流磁控溅射技术在304不锈钢双极板表面沉积Cr₂AlC MAX相涂层。利用扫描电镜(SEM)、X射线衍射(XRD)、X射线光电子能谱(XPS)等对涂层的形貌、微观组织进行分析；采用电化学方法研究了Cr₂AlC涂层对不锈钢在0.01 mol/L H₂SO₄溶液中耐蚀性能的影响。结果表明：涂层致密均匀，主要由Cr₂AlC MAX相组成；沉积Cr₂AlC涂层后，304不锈钢的腐蚀电流密度为2.43×10^-7A·cm^-2，下降了两个数量级；恒电位极化后，阳极和阴极的电流密度分别稳定在2.44×10^-8和2.3×10^-7A·cm^-2；在腐蚀介质中的电荷转移电阻值高于10⁵Ω·cm²，表明Cr₂AlC涂层在质子交换膜燃料电池模拟环境中具有良好的耐腐蚀性能。     

离散铬纳米核对超薄铜箔剥离性能和电阻率的影响（英文）

提出一种利用电化学沉积法制备Cr纳米离散晶核实现超薄铜箔剥离的策略。结果表明,该方法可以制备厚度约为1.34μm的铜箔。Cr纳米离散晶核密度直接影响铜箔的剥脱性能、表面粗糙度和电阻率。当Cr纳米离散晶核密度为15.7×10⁹ cm^-2时,铜箔的剥离性能最好,电阻率为4.95×10^-7Ω·m,比常规厚度为0.67μm Cr涂层的电阻率低9.2%,比重铬酸钾涂层的电阻率低15.8%,抗拉强度超过248.80 MPa。     

ChCl-EG低共熔溶剂体系中镍沉积的电化学行为研究

目的 研究镍在低共熔溶剂体系中的电沉积、电化学行为及形核方式。方法 使用循环伏安法和计时电流法,研究在氯化胆碱-乙二醇（ChCl-EG）低共熔溶剂体系中镍沉积的电化学行为及其形核理论。 采用SEM测试手段对镍电沉积层的微观形貌进行观察和分析,同时采用EDS分析镍镀层的元素组成。 结果 ChCl-EG低共熔溶剂的电化学窗口为2.63 V,镍在ChCl-EG低共熔溶剂体系中的氧化、还原电位分别为0.79 V和-0.34 V。不同扫描速度的循环伏安曲线表明,在扫速为10~50 mV/s时,Ep与v无关,呈现出可逆反应的特性;而当扫速增加到50~90 mV/s时,Ep随v的增加而呈现负移的趋势,符合不可逆反应的特性。可以判断镍（Ⅱ）在ChCl-EG低共熔溶剂中属于准可逆反应。在“电流滞环”-1.00 ~ -1.08 V下测定计时电流曲线,通过拟合计时电流曲线与理论模型对比发现,镍（Ⅱ）在ChCl-EG体系中的电结晶过程符合Scharifker-Hill三维形核模型。镍电沉积层在铜基体上分布均匀,镀层中只含有镍元素。结论 镍（Ⅱ）在氯化胆碱-乙二醇低共熔溶剂中的电沉积过程是准可逆反应且形核机制为三维瞬时成核,通过ChCl-EG低共熔溶剂体系可以得到纯度高并且分布均匀的镍镀层,且镍镀层的颗粒尺寸为22.1 nm。     

AZ31/AZ61/AZ91镁合金超塑性压缩变形的本构方程

对再结晶退火后的AZ31、AZ61、AZ91镁合金进行热压缩试验，研究该系列镁合金在变形温度423～673 K和应变速率1×10^-4～1×10^-2 s^-1范围的超塑性行为，分析工艺参数、显微组织和超塑性行为之间的关系。试验结果表明，在673 K和1×10^-2 s^-1的初始应变速率下，该系列镁合金的应力应变曲线表现为明显的超塑性特征，其应变速率敏感指数分别为0.25、0.23、0.24，超塑性变形激活能分别为105.8、165.4、126.2 kJ/mol，接近其晶界自扩散活化能，并由此建立相应的超塑性压缩本构方程。     

稀土金属对铅合金阳极电化学性能和腐蚀行为的影响

为研究稀土金属对铜电积用铅合金阳极性能的影响，采用二步重熔法制备了不同稀土含量的铅合金。随后检测了合金的硬度、导电性、析氧过电位、耐蚀性能、电流效率和能耗。结果表明：微量稀土金属能改善铅合金的铸造性能，优化显微组织，提高硬度，降低电子散射率，提高电导率，提高电化学活性，降低析氧过电位，提高腐蚀电位，降低腐蚀电流，提高耐蚀性能，降低槽电压，提高电流效率，降低电积能耗；稀土金属质量分数为0.2%的合金硬度为41 HV0.1,电导率为4.87 MS/m,析氧过电位为0.837 V,腐蚀电位为0.633 V,腐蚀电流为1.245×10^-4 A/cm²,槽电压为1.81 V,电流效率为92.28%,电积能耗为1 653.48 kW·h/t铜。     

直接激光沉积Fe-Cr-Ni梯度合金钢的组织与性能

采用直接激光沉积技术制备了具有外强内韧组织性能的12CrNi2Y-50Cr6Ni2Y-70Cr8Ni2Y梯度合金钢试样,利用光学显微镜、扫描电镜、透射电镜、硬度计、摩擦试验机等分析手段,对直接激光沉积的梯度合金钢试样的组织结构、界面结合性、硬度梯度分布及耐磨性等进行了研究。结果表明,在优化的激光沉积参数下,成功制备出了无裂纹夹杂缺陷、梯度过渡界面处呈现冶金结合的12CrNi2Y-50Cr6Ni2Y-70Cr8Ni2Y梯度合金钢试样。梯度合金钢的组织呈现出由粒状贝氏体+板条贝氏体+少量马氏体→板条贝氏体+板条马氏体→板条马氏体+片状马氏体的变化趋势,对应硬度呈356 HV0.2→551 HV0.2→712 HV0.2梯度分布,体积磨损率呈现2.01×10^-4 mm³·N^-1·m^-1→1.33×10^-4 mm³·N^-1·m^-1→0.71×10^-4 mm³·N^-1<...     

熔融镍渣等温氧化动力学研究

研究了富铁熔融镍渣在空气气氛下的等温氧化动力学行为。利用高温激光共聚焦显微镜(HT-CLSM)确定三元碱度0.6调质镍渣的实际熔融温度(液相线温度)为1488℃。通过管式炉等温氧化试验，获取温度1500～1575℃下熔融镍渣氧化过程Fe²⁺浓度-时间曲线，采用微分法和Arrhenius方程计算出熔渣中Fe²⁺的氧化反应级数为1.45～1.26，表观活化能为286.83 k J/mol，明确熔融镍渣氧化动力学主要受扩散传质控速。基于双膜理论和渗透理论，估算出1500～1575℃熔渣中氧的扩散系数分别为2.02×10^-9～4.42×10^-9 m²/s和0.50×10^-9～2.19×10^-9 m²/s，双膜理论估算出的氧扩散系数更具参考意义。     

A Study on the Electrodeposition Mechanism of Palladium from Ammoniacal Solution Using a Rotating Pt Ring-Cu Disk Electrode

The electrodeposition of palladium in ammonium phosphate solution (pH=10) containing 0.025 M tetramminepalladium(II) ion has been studied at room temperature by means of cyclic voltammetry, potentiostatic current transients and ac impedance measurements on a rotating Pt ring-Cu disk electrode, Cyclic voltammograms and potentiostatic current transients exhibited the characteristic features of the mechanism of progressive nucleation and growth under interfacial electron transfer and diffusion control. The interfacial reaction-controlled growth condition was established on the reverse sweep of the cyclic voltammogram. From the reverse sweep curve of cyclic voltammetry done at various rotation speeds, a Tafel plot of -210 mV per decade and diffusivity of tetramminepalladium(II) ion of 1.4 × 10^?5 cm² s^?1 were obtained. During the electrodeposition of palladium on the Cu-disk electrode, the ring current increased in the anodic direction, indicating the oxidation of reaction intermediates produced on the disk electrode. Complex-plane impedance spectra obtained in the potential range of-0.76 to -0.8 V(SCE) showed a semicircle in the high frequency region and an inductive loop in the low frequency region. Based upon the experimental results, it is suggested that the electrodeposition of palladium from tetrammine palladium(II) ion proceeds partly via two consecutive reactions with the formation of a monovalent reaction intermediate and partly via a direct two electron discharge reaction in which the intermediate acts as a catalyst associated with propagating kink sites.     

Electrochemical behavior of tantalum in ethylene carbonate and aluminum chloride solvate ionic liquid

To investigate the electrochemical reduction mechanism of Ta(V) in ethylene carbonate and aluminum chloride (EC−AlCl₃) solvate ionic liquid, cyclic voltammetry experiments were conducted on a tungsten working electrode. Four reduction peaks were observed in the cyclic voltammogram of the EC−AlCl₃−TaCl₅ ionic liquid. The reduction peaks at −0.55, −0.72, and −1.12 V (vs Al) were related to the reduction of Ta(V) to tantalum metal by three stages including the formation of Ta(IV) and Ta(III) complex ions. The reduction of Ta(III) to tantalum metal was an irreversible diffusion-controlled reaction with a diffusion coefficient of 3.7×10⁻⁷ cm²/s at 323 K, and the diffusion activation energy was 77 kJ/mol. Moreover, the cathode products at 323 K were characterized by scanning electron microscopy, energy-dispersive spectroscopy, and X-ray photoelectron spectroscopy. The results showed that tantalum metal and tantalum oxides were obtained by potentiostatic electrodeposition at −0.8 V for 2 h.     

Electrochemical behavior of zirconium in molten NaCl-KCl-K<Subscript>2</Subscript>ZrF<Subscript>6</Subscript> system

The electrochemical reduction of Zr4+(complex) ions in NaCl-KCl-K2ZrF6 molten salt on Pt electrode was investigated using cyclic voltammetry and square wave voltammetry at 1023 K.Two cathodic reduction peaks related to Zr4+/Zr2+ and Zr2+/Zr steps were observed in the cyclic voltammograms.The result was also confirmed by square wave voltammetry.The diffusion coefficient of Zr4+(complex) ions at 1023 K in NaCl-KCl-K2ZrF6 melt,measured by cyclic voltammetry,is about 4.22×10-6 cm2/s.The characterization of the deposits obtained by potentiostatic electrolysis at different potentials was investigated by XRD,and the results were well consistent with the electrochemical reduction mechanism of Zr4+(complex) ions.     

Effects of 3-Thiothiol-1-propane-sulphonic acid sodium salt and Sulphuric Acid on the Initial Stages of Copper Electrodeposition

Initial stages of copper electrodeposition on a glassy carbon electrode from acid sulphate solutions are studied using cyclic voltammetry and chronoamperometry. The electrolyte consisted of 0.05 mol dm³ copper sulphate and 1.4 ～ 1.8 mol dm ³ sulphuric acid containing 2 × 10² g dm ³ 3-thiothiol-l-propane-sulphonic acid sodium salt (NaO₃S (CH₂)₃ SSH). The results show that the additive produces an initial inhibition of copper deposition, probably related to the adsorption whereas sulphuric acid promotes copper electrodeposition. The initial deposition kinetics corresponds to a model including instantaneous nucleation and diffusion controlled growth. Addition of 3-thiothiol-l-propane-sulphonic acid sodium salt and sulphuric acid does not change the initial nucleation of copper electrocrystallisation but it increases the nucleation rate and the number density of nuclei at the surface.     

Physicochemical properties of DMI–LiNO3 solvated ionic liquid and its application in electrodeposition of neodymium at room temperature

The density, conductivity, and viscosity of the 1,3-dimethyl-2-imidazolinone and lithium nitrate (DMI– LiNO₃) solvated ionic liquid were measured as a function of temperature. Additionally, the electrochemical mechanism and electrodeposition of neodymium from the DMI–LiNO₃ solvated ionic liquid were investigated. Cyclic voltammetry results indicate that the electrochemical reduction of Nd(III) is irreversible and proceeds via one-step with three-electron transfer, which is controlled by diffusion with a diffusion coefficient of 5.08×10⁻⁸ cm²/s. Energy- dispersive X-ray spectrometry and X-ray photoelectron spectroscopy data confirm that the electrodeposit obtained after electrodeposition at −4 V (vs Ag) using the DMI–LiNO₃–Nd(CF₃SO₃)₃ solvated ionic liquid contains metallic neodymium.     

In-situ synthesis of silicide coatings on molybdenum substrates by electrodeposition in chloride-fluoride molten salts

Silicide coatings including MoSi₂ and Si-MoSi₂ were prepared on molybdenum substrates by electrodeposition in NaCl-KCl-NaF-K₂SiF₆ molten salt. The experimental was conducted under different cathodic current densities at the temperature of 1073 K. The effect of the current density on the microstructure, phase composition, cross-section morphologies and elemental distribution of the as-prepared coatings were investigated by means of SEM, XRD and EDX. The results revealed that the type of the silicide coatings was strongly dependent on the current density and the relevant deposition mechanism was discussed. Besides, the electrochemical behavior of silicon ion in the chloride-fluoride molten salts was also studied using cyclic voltammetry and chronopotentiometry to reveal the electroreduction mechanism. The reduction of Si(IV) to Si was proved to be a quasi-reversible or irreversible diffusion-controlled single-step reaction and the diffusion coefficient of Si(IV) calculated from chronopotentiograms was (1.28 ± 0.25) × 10⁻⁵ cm²·s⁻¹.     

从模拟高放射废液中电化学回收钯和银

为从高放射废液(HLLW)中回收钯和银,采用循环伏安法和恒电位沉积法研究钯和银在模拟硝酸溶液中的电化学行为.利用扫描电子显微镜(SEM)和X射线衍射仪(XRD)观察沉积产物的形貌并分析其组成.结果表明,在单独电沉积银时亚硝酸根的生成促进银的溶解.当同时电沉积钯和银时,相同时间内更多金属被沉积,且沉积的银没有再出现溶解....     

Redox behavior of indium in molten chlorides

An electrochemical study on the redox behavior of indium in the eutectic LiCl-KCl system at 450 °C was carried out with the transient techniques of cyclic voltammetry and chronopotentiometry on an inert molybdenum electrode. The reduction of In(III) was found to be a two-step process involving In(III)/In(I) and In(I)/In couples at the potentials of about ?0.4 and ?0.8 V versus Ag/AgCl, respectively. The redox mechanism was further confirmed by the theoretical evaluation of the number of transferred electrons based on cyclic voltammetry and characterizations of the precipitates generated by the potentiostatic electrolysis. The diffusion coefficients of indium ions in the eutectic LiCl-KCl melt at 450 °C were estimated by cyclic voltammetry and chronopotentiometry. The results obtained through the two methods are in fair agreement, delivering an average diffusion coefficient of approximately 1.8×10^?5 cm²/s for In(III), and 1.4×10^?4 cm²/s for In(I).     

Electrolytic production of Cu-Ni alloys in CaCl2-Cu2S-NiS molten salt

An alternative metal/alloy production method, known as direct electrochemical reduction (DER), was introduced for the fabrication of CuNi alloys from mixed sulfides (Cu₂S, NiS) under both galvanostatic and potentiostatic conditions. The influences of the process parameters (e.g., cell voltage and current) on the compositions of the reduced compounds were investigated to yield industrially desirable alloys, namely, CuNi10, CuNi20, and CuNi30. The electrochemical behaviors of Cu₂S and NiS in CaCl₂ melt were examined at a temperature of 1200 °C via cyclic voltammetry (CV). Based on the CV results, the cathodic reduction of Cu₂S occurred in one step and cathodic reductions of NiS occurred in two steps, i.e., Cu₂S?Cu for copper reduction and NiS?Ni₃S₂ ?Ni for nickel reduction. Galvanostatic studies revealed that it was possible to fabricate high-purity CuNi10 alloys containing a maximum sulfur content of 320×10^?6 via electrolysis at 10 A for 15 min. Scanning electron microscopy along with energy-dispersive X-ray spectrometry and optical emission spectroscopy (OES) examinations showed that it was possible to fabricate CuNi alloys of preferred compositions and with low levels of impurities, i.e., less than 60×10^?6 sulfur, via DER at 2.5 V for 15 min.     

Electrodeposition of Li and electrochemical formation of Mg–Li alloys from the eutectic LiCl–KCl

The electrochemical behavior of Li⁺ was studied at the inert and active electrodes in the molten LiCl–KCl eutectic. Transient electrochemical techniques, such as cyclic voltammetry, chronoamperometry and chronopotentiometry were used in order to explore the deposition mechanism of Li. The reduction process of Li⁺ is irreversible and the diffusion coefficient of Li⁺ at 723 K was determined as 6.68(±0.07) × 10⁻⁶ cm² s⁻¹. During the electrodeposition process of Li, the electrocrystallization played an important role. The chronoamperometric studies indicated that instantaneous nucleation existed during the electrodeposition process of Li metal. At a Mg electrode, the electroreduction of Li⁺ takes place at a less cathodic potential values than that at Mo electrode which indicated the formation of Mg–Li alloy. The Mg–Li alloy films with different crystal phase were obtained by potentiostatic electrolysis, and the samples were characterized by X-ray diffraction and scanning electron microscopy.