Mn对铝-锰合金组织和锌电积过程锌成核的影响

为了研究Mn元素对铝合金阴极在电积锌过程中锌的成核机理的影响，利用废弃的1070铝阴极熔炼并制备了不同Mn元素含量的Al-Mn合金，并分析Mn元素添加对铝合金金相组织的影响。采用线性伏安扫描、恒电流极化和恒电位阶跃计时电流等手段研究1070纯铝和Al-Mn合金阴极在酸性硫酸锌体系中锌的成核机理，分析不同Mn元素含量对铝合金阴极的析氢和析锌动力学的影响规律；采用扫描电镜观察金属锌在阴极表面的初期形核规律。结果表明：一定范围内的Mn元素添加对铝合金组织具有细化作用；Mn元素添加能降低铝合金阴极的析氢过电位（最多高达120 mV）和锌析出过电位（最多为80 mV），增大交换电流密度（最多增大4个数量级），从而提高阴极的电催化活性，使锌更容易在阴极合金表面析出；在锌的初期成核过程中，Al-0.6%Mn阴极沉积锌速率最快；1070纯铝和Al-0.6%Mn阴极上锌的成核均遵循三维瞬时成核机理，但Al-0.6%Mn与理论瞬时成核的吻合度更高；从沉积机理来看，沉积锌的质量由形核速率和形核数密度两个方面决定。

Effect of Mn on Microstructure of Aluminum-manganese Alloy and Zinc Nucleation during Zinc Electrowinning

In order to study the effect of Mn on the nucleation mechanism of zinc on aluminum alloy cathode in electrowinning zinc, Al-Mn alloys with different Mn contents were prepared by smelting the waste 1070 aluminum cathode. The effect of Mn on the metallographic structure of aluminum alloy was analyzed. The nucleation mechanism of zinc in pure 1070 aluminum and Al-Mn alloy cathodes under acidic zinc sulfate system was investigated by means of linear sweep voltammetry, constant current polarization and chronoamperometry. The influence discipline of different Mn contents on the hydrogen evolution kinetics and zinc kinetics of aluminum alloy cathodes were explored, and the initial nucleation evolution of metal zinc was observed by scanning electron microscopy. The results show that the addition of Mn within a certain range has a refinement effect on the microstructure of aluminum alloy, reduces the hydrogen evolution overpotential (to the greatest extent 120 mV) and the precipitation overpotential of zinc (to the greatest extent 80 mV). Besides, the addition of Mn would increase the exchange current density (to the greatest extent 4 orders of magnitude), thereby improving the electrocatalytic activity of the cathode and enabling zinc to be more easily precipitated. In the initial nucleation of zinc, the Al-0.6% Mn cathode has the fastest zinc deposition rate. The nucleation of zinc on 1070 pure aluminum and Al-0.6% Mn cathodes follows a three-dimensional instantaneous nucleation mechanism, but Al-0.6% Mn maintains good agreement with theoretical instantaneous nucleation curve. From the deposition mechanism, the quality of deposited zinc is determined by nucleation rate and nucleation number density.?