摘要
采用Hydra/Medusa软件、循环伏安法(CV)和计时电流法(CA)研究了pH对柠檬酸盐体系镀液中Zn^(2+)、Fe^(2+)、Mn^(2+)的化学形态分布及Zn–Fe–Mn合金电沉积行为的影响。采用扫描电镜(SEM)、能谱仪(EDS)和X射线衍射仪(XRD)分析了不同pH下所得镀层的表面形貌、成分及相结构。结果表明,当pH为3.0~5.0时,镀液中Zn^(2+)、Fe^(2+)和Mn^(2+)的配合物稳定常数差别巨大,Zn–Fe–Mn合金共沉积比较困难,CV曲线仅出现Zn–Fe合金还原峰,所得镀层中Mn含量极低(质量分数仅0.36%~0.50%)。随pH升高,镀层的Zn质量分数减小,相组成由η(Zn)和Γ_(1)(Fe_(11)Zn_(40))向Γ(Fe_(3)Zn_(10))和δ1(FeZn_(6.67))转变,晶粒由金字塔形转变为胞状。当pH为6.0时,镀液中Zn^(2+)、Fe^(2+)和Mn^(2+)的配合物稳定常数相近,能够共沉积得到Mn质量分数达9.40%的Zn–Fe–Mn合金镀层,其相结构包含了Zn在α-Fe中的固溶体和FeMn_(4)。Zn–Fe–Mn合金的共沉积是不可逆过程,成核机制为瞬时成核。
The chemical species distribution of several ions including Zn^(2+),Fe^(2+),and Mn^(2+)in citrate-based electrolyte and their electrodeposition behaviors were studied by Hydra/Medusa software,cyclic voltammetry(CV),and chrono-amperometry(CA).The surface morphology,elemental composition,and phase constitution of the coatings electrodeposited at different pH values were analyzed by scanning electron microscopy(SEM),energy-dispersive spectroscopy(EDS),and X-ray diffraction(XRD).The results showed that the co-electrodeposition of Zn-Fe-Mn alloy is hard at pH 3.0-5.0 due to the great difference between the stability constants of the complexes of Zn^(2+),Fe^(2+),and Mn^(2+).There was only a reduction peak of Zn-Fe alloy in CV curve,and the mass fraction of Mn in deposit was as low as 0.36%-0.50%.With the increasing of pH,the content of Zn in deposit was decreased,the morphology of deposit transferred from pyramid to cellular shape,and the phases were changed fromη(Zn)+Γ_(1)(Fe_(11)Zn_(40))toΓ(Fe_(3)Zn_(10))+δ1(FeZn_(6.67)).The stability constants of the complexes of Zn^(2+),Fe^(2+),and Mn^(2+)at pH 6.0 are close,so a Zn-Fe-Mn alloy coating containing 9.40%(mass fraction)of Mn can be obtained.The Zn-Fe-Mn alloy coating was mainly composed ofα-Fe with Zn in solid solution and FeMn_(4).The co-electrodeposition of Zn-Fe-Mn alloy is irreversible and follows the instantaneous nucleation mechanism.
作者
周宏桥
杨海丽
ZHOU Hongqiao;YANG Haili(College of Metallurgy and Energy,North China University of Science and Technology,Tangshan 063210,China)
出处
《电镀与涂饰》
CAS
北大核心
2023年第7期8-15,共8页
Electroplating & Finishing
基金
国家自然科学基金(51474088)。
关键词
锌–铁–锰合金
酸度
电沉积行为
成核机制
zinc–iron–manganese alloy
acidity
electrodeposition behavior
nucleation mechanism
