柠檬酸钠对Ni-Sn-Mn合金电沉积行为及耐蚀性的影响

为了探索柠檬酸钠在Ni-Sn-Mn合金电沉积过程中的作用机制,采用扫描电子显微镜、阴极极化曲线、循环伏安曲线、电化学阻抗、恒电位阶跃及Tafel曲线等方法,研究了柠檬酸钠的浓度对Ni-Sn-Mn合金的表面形貌、电沉积行为及耐蚀性的影响。结果表明:随着柠檬酸钠浓度的增加,Ni-Sn-Mn合金电沉积的阴极极化增强,沉积电位负移,电荷转移电阻增大;不同柠檬酸钠浓度下的电沉积过程均不可逆,并且电结晶过程遵循由电荷传递过程和扩散过程共同控制的三维连续成核机制;当柠檬酸钠的浓度为0.5mol/L时,镀层最为均匀、细密,在质量分数为3.5%的NaCl溶液中具有最正的自腐蚀电位及最小的自腐蚀电流密度,耐蚀性最好。     

Ni-Co-W合金电沉积行为及成核机理

采用循环伏安、阴极极化曲线、电化学阻抗谱、计时电流等方法对Ni-Co-W合金的电沉积行为及成核机理进行研究.结果表明,Ni-Co-W合金的电沉积是一个存在成核行为的不可逆过程.Ni-Co-W合金的成核机制为瞬时成核,合金的电沉积由动力学和扩散过程混合控制,主要受动力学控制.     

不同添加剂对Ni-Sn-Mn合金电沉积行为的影响

采用阴极极化曲线、循环伏安曲线、电化学阻抗和电位阶跃等电化学方法,研究了糖精(BSI)、1,4-丁炔二醇(BYD)及两种添加剂组合对Ni-Sn-Mn合金电沉积行为的影响。结果表明:加入不同添加剂均使Ni-Sn-Mn合金电沉积的阴极极化增大,沉积电位负移,对合金电沉积起阻化作用;不同添加剂作用下电沉积过程均为不可逆;加入BSI的电荷转移电阻大于加入BYD的电荷转移电阻,而加入BSI+BYD的电荷转移电阻最大;在不同添加剂作用下Ni-Sn-Mn合金电沉积无因次曲线接近理论连续成核曲线,电沉积结晶过程遵循三维生长方式的连续成核机制。     

锡阴电极的制备及析氢性能的研究

为了提高锡电结晶过电位,改善锡镀层表面形貌和制备较好的镀锡电极,通过电镀技术在室温条件下制备了不同电镀液条件下的锡镀层,运用线性伏安法、交流阻抗法和电势阶跃法等电化学方法和SEM技术研究了酸性镀锡体系中明胶对锡沉积的影响。阴极极化曲线和交流阻抗曲线表明,明胶能增大锡沉积反应的电荷传递内阻,提高锡电沉积过电位,延缓锡电沉积反应。电势阶跃表明,锡的电结晶过程遵循扩散控制瞬时成核和三维生长方式的结晶机理。SEM分析结果表明,添加明胶能使锡镀层光滑致密、晶粒细小。电极的极化曲线表明,镀锡电极能提高析氢电位,其中添加明胶所得的锡电极的析氢效果最好。     

钛基锡锑中间层上二氧化铅电沉积过程的研究

运用电化学手段研究了钛基锡锑中间层上二氧化铅的阳极电沉积过程.循环伏安曲线表明,二氧化铅的电沉积经历了晶核形成过程,通过恒电位阶跃暂态曲线可知,二氧化铅在Ti/SnO2-Sb2O5电极上的电沉积初始过程遵循扩散控制的瞬时成核和三维长大方式,且随着过电位的增加,电极表面上晶核数增多.     

pH值对Ni-Cr-Mo合金电沉积机制的影响

采用循环伏安曲线、电化学阻抗谱、扫描电镜、能谱仪等手段,研究了pH值对Ni-Cr-Mo合金电沉积机制的影响。结果表明:当pH值为3.0时,循环伏安曲线的共沉积还原峰最正,电化学阻抗谱的极化电阻最小,Ni-Cr-Mo合金的电沉积最容易发生。当pH值不大于3.0时,Ni-Cr-Mo合金的电沉积受动力学和扩散混合控制;当pH值大于3.0时,Ni-Cr-Mo合金的电沉积受动力学过程控制。随着pH值的增大,Ni-Cr-Mo合金的晶粒尺寸逐渐增大,Cr的质量分数先增大后减小,Ni、Mo的质量分数均先减小后增大。     

酒石酸钾钠对HEDP镀铜形核的影响

研究了酒石酸钾钠对羟基乙叉二膦酸(HEDP)镀铜形核的影响。通过线性扫描伏安、交流阻抗和循环伏安曲线研究铜沉积的电化学行为。随着镀铜液中酒石酸钾钠含量的提高,阴极极化曲线负移,X-射线衍射结果表明,晶粒由44 nm减小到40 nm;酒石酸钾钠的加入使循环伏安电流环消失;在-1.44、-1.45和-1.46 V的电位下,酒石酸钾钠的质量浓度在0~21 g/L内,镀液中铜离子在玻碳电极上的形核方式都为三维瞬时形核,不改变铜的形核方式;酒石酸钾钠的质量浓度增加到21 g/L,成核数密度和晶核垂直生长速率较基础液都有所增大;在电位-1.00~-1.20 V之间,铜络离子还原的表观反应活化能随着电位负移而减小,表观反应活化能由14 k J/mol增大到25 k J/mol,电极反应由扩散控制转向扩散过程和电极反应过程联合控制。     

钛基镍-铁合金电极的制备及其析氢性能

采用恒电位电沉积法,在钛板上制备Ni-Fe合金电极。通过测量Ni-Fe合金电极在1 mol/L NaOH溶液中的阴极极化曲线,讨论了电沉积液中FeSO_4·7H_2O质量浓度、电沉积电位和时间对Ni-Fe合金电极析氢性能的影响,得到电沉积的最优工艺条件为:NiSO_4·6H_2O 100 g/L,FeSO_4·7H_2O 15 g/L,H_3BO_3 20 g/L,抗坏血酸5 g/L,十二烷基硫酸钠1 g/L,pH=3.5,温度25℃,电位-1.3 V(相对于饱和甘汞电极),时间30 s。当电流密度为0.05 A/cm~2时,Ni-Fe合金电极在1 mol/L NaOH溶液中的析氢过电位比Ni电极低23%。Ni-Fe合金电极表面比Ni电极表面粗糙,其表面的Ni、Fe含量比约为2:3。     

电沉积制备Ni-Co合金镀层的成核过程研究

在氨基磺酸盐镀液中,采用电沉积技术制备了Ni-Co合金镀层。通过阴极线性扫描和计时电流测试,研究了Ni-Co合金镀层电结晶初期的共沉积行为和电化学反应过程,探究了Ni-Co合金镀层的成核模型;采用扫描电子显微镜和X射线衍射仪,表征了Ni-Co合金镀层的表面形貌和微观结构;通过退火后的显微硬度测试,研究了Ni-Co合金镀层的热稳定性。结果表明:Ni-Co合金镀层的沉积电位约为-0.73 V;Ni-Co合金镀层的形核/生长过程符合受扩散控制的瞬时成核模型;Ni-Co合金镀层表面均匀致密,晶粒细小,热稳定性较好。     

Co-Ni-Cu合金镀层的电沉积机制及性能研究

使用循环伏安曲线和交流阻抗谱,研究了柠檬酸体系中Co-Ni-Cu合金镀层的电沉积机制。同时,研究了电流密度对Co-Ni-Cu合金镀层的表面形貌、成分、结合力、耐磨性及表面粗糙度的影响。结果表明:在不同电位下金属离子以不同的状态发生还原,并且钴镍还原反应首先生成吸附性产物M(OH)_(ads),然后在电极表面进一步还原为原子态。当电流密度为3.47 A/dm~2时,Co-Ni-Cu合金镀层形成均匀、细小的晶粒,表面粗糙度最小,结合力与耐磨性最好。     

Zinc-nickel alloy deposition in the presence of citrate ions

A new bath for zinc-nickel alloy electrodeposition has been studied using citrate as a complexant. Citrate ion was found to increase the zinc content of the alloy. Cyclic voltammetric studies were carried out to elucidate the effect of citrate ion in codeposition. The cathodic and anodic peaks indicate that due to efficient control of surface pH citrate ions cause depolarization during deposition. The absence of two cathodic peaks with decreasing nickel/zinc ratio reappeared in the presence of citrate ion. This led, not only to increased zinc content in the alloy, but also to reduced impurity content which affected the mechanical properties. This effect has been studied at varying zinc/nickel ratios and scanning potential ranges.     

电沉积锌钴磷合金时阴极行为的研究

用动电位扫描法研究了在氯化物镀液中电沉积Ｚｎ－Ｃｏ－Ｐ合金时的阴极行为。认为在镀液中加入配体柠檬酸钠可以提高阴极极化。加入次磷酸钠有利于合金镀层的形成。     

Kinetics of the hydrogen evolution reaction on Fe–Mo film deposited on mild steel support in alkaline solution

The mechanism and kinetics of the hydrogen evolution reaction were studied in 1.0 mol dm⁻³ NaOH solution on Fe–Mo alloy electrodes prepared by electrodeposition at constant current densities from a pyrophosphate bath. A series of electrode containing 34–59 at.% Mo was prepared. Electrodes displayed porous character, and electrochemical impedance spectroscopy was used to characterized real surface area. It was found that within the whole potential region the mechanism of the HER is a consecutive combination of the Volmer step, followed dominantly by a rate controlling Heyrovsky step, while the contribution of the parallel Tafel step is negligible. The kinetic parameters of the HER were determined. With an increase in the molybdenum content, the electrodes become more active, and an increase in the real surface area is observed. The main factor influencing the electrode activity seems to be the real surface area.     

高活性镍钴铁三元合金电极的制备及析氢性能研究

为进一步提高镍基电极的析氢性能,采用恒电位沉积法,通过改变镀液中各合金的质量浓度比、沉积电位、沉积时间等条件,制备出一种高活性的镍钴铁三元合金电极。通过测定电极在1 mol/L的NaOH溶液中的极化曲线,得到最佳的沉积工艺条件为:36.25 g/L NiSO_4·6H_2O,1.25 g/L NiCl_2·6H_2O,5 g/L CoSO_4·7H_2O,7.5 g/L FeSO_4·7H_2O,10 g/L H_3BO_3,0.5 g/L抗坏血酸,1 g/L十二烷基硫酸钠,pH=4.0,电沉积电位-1.45 V,电沉积时间300 s。阴极极化曲线测试结果表明在5 A/dm^2的条件下,镍钴铁三元合金电极的析氢过电位降低至121 mV,相比于纯镍电极过电位降低近50%,相比于镍钴电极过电位降低近35%。     

电沉积Ni-S、Ni-P-S合金析氢阴极的研究

在电沉积法制备Ni-S合金电极的基础上,向镀液中添加次亚磷酸钠制备了Ni-P-S合金电极。电化学测试结果表明,Ni-P-S和Ni-S合金电极的催化性能都要好于其它电极,Ni-P-S合金电极的性能随着次亚磷酸钠质量浓度的升高而降低。计算了电极的电极反应动力学参数(包括Tafel斜率b、交换电流密度0ρ和过电位η),解释了Ni-P-S合金电极和Ni-S合金电极在不同电流密度区活性不同的原因。恒电流电解表明,Ni-P-S合金电极具有较高的稳定性。电极的微观形貌用SEM进行表征,成份用能谱进行分析,通过X射线衍射分析电极的晶型结构。     

铁电极上HEDP镀铜的电化学行为

通过测量开路电位一时间曲线和阴极极化曲线,研究了HEDP镀铜液在金属铁上电沉积铜的电化学行为.结果表明,HEDP镀铜液的组成影响金属铁在溶液中的稳定开路电位和金属铁上电沉积铜的阴极极化.增大溶液中HEDP的浓度或提高HEDP与Cu2+的摩尔比,铁电极的稳定开路电位负移,可减缓和消除铁与铜离子的置换反应,提高铜镀层与铁基体的结合力;金属铁上电沉积铜的阴极极化增大,有利于得到致密的铜镀层.镀液pH升高,铁在镀液中的稳定开路电位稍有正移,但在金属铁上电沉积铜的阴极极化增大,在HEDP镀铜液中电沉积铜的阴极过程发生电化学极化,阴极极化曲线服从Tafel关系.     

变形锌合金在柠檬酸盐镀镍液中的腐蚀行为

利用动电位极化曲线和电化学阻抗谱研究了变形锌合金在柠檬酸盐电镀镍溶液中的腐蚀行为,通过场发射扫描电镜(SEM–EDS)表征了腐蚀表面形貌和成分。结果表明,锌合金在镀液中呈活性溶解状态,柠檬酸钠对锌合金有缓蚀作用;提高镀液温度不仅加剧锌合金腐蚀,还会加快镍置换反应发生。     

Reaction and nucleation mechanisms of copper electrodeposition from ammoniacal solutions on vitreous carbon

The reaction and nucleation mechanisms of the electrodeposition of copper from ammoniacal solutions were investigated by cyclic voltammetric (cv) and chronoamperometric (ca) techniques, respectively. Each experiment with both electrochemical techniques was followed by morphological studies by atomic force microscopy (AFM). With respect to pH, the studies were performed on ammoniacal solutions at pH 4, pH 6, and pH 8, each representing a characteristic predominance region in E-pH diagrams. The experimental parameters were copper concentration, scanning rate, deposition potential, and electrode conditioning. It was found that at pH 4 copper electrodeposition occurs via reduction of cupric species to cuprous, which in turn can be either reduced, or disproportionated to metallic copper. At pH 6, deposition occurs from free and complexed cupric species, while at pH 8, only cupric amine complexes are involved. Copper nucleates according to instantaneous mechanisms at pH 4, and progressive nucleation mechanisms at pH 6 and pH 8. The diffusion coefficients of the copper species involved were also determined and are reported in this study.