Al-Zn-In-Si牺牲阳极在模拟海水及海泥环境中的电化学性能

目的 分析A13型Al-Zn-In-Si牺牲阳极在海水、海泥中的电化学性能.方法 采用恒电流极化进行4 d的加速实验,使用电化学阻抗谱(EIS)分析电化学腐蚀过程,通过扫描电子显微镜(SEM)、能谱分析(EDS)及三维超景深显微镜观察分析腐蚀形貌及表面化学成分,对比研究了Al-Zn-In-Si牺牲阳极在模拟海水和海泥环境下的腐蚀形貌、电化学性能.结果 在模拟海水和海泥环境中,尽管Al-Zn-In-Si牺牲阳极都满足DNVGL-RP-B401的要求,但在海泥环境中,其电化学效率仅为65.97％,远低于海水环境中的89.43％.牺牲阳极在海水环境中发生均匀腐蚀,而在海泥环境中却呈现严重的不均匀腐蚀现象,表面腐蚀坑为疏松多孔蜂窝状.结论 在海泥环境下,Al-Zn-In-Si牺牲阳极的腐蚀产物扩散困难,局部呈现腐蚀坑,自腐蚀速率高,导致电化学效率降低.溶解过程中,由于组织脱落,自身消耗增加,电化学容量降低,从而导致阳极在模拟海泥环境中的电化学性能低于海水环境,并揭示了阳极在模拟海水、海泥环境中的腐蚀机理.

Electrochemical Performance of Al-Zn-In-Si Sacrificial Anode in Simulated Seawater and Sea Mud Environment

This paper is to analyze the electrochemical performance of A13 Al-Zn-In-Si sacrificial anode in seawater and sea mud. The four-day galvanostatic polarization acceleration test was carried out by constant current polarization. The electrochemical corrosion process was analyzed by electrochemical impedance spectroscopy (EIS). The corrosion morphology and surface chemical composition were presented by scanning electron microscope (SEM), energy spectrum analysis (EDS) and three-dimensional depth of field microscope. The corrosion morphology and electrochemical performance of Al-Zn-In-Si sacrificial anodes under simulated seawater and sea mud environments were comparatively studied. In the simulated seawater and sea mud environment, although Al-Zn-In-Si sacrificial anode met the requirements of DNVGL-RP-B401, the electrochemical efficiency in the sea mud environment was only 65.97%, far lower than 89.43% in seawater environment. The sacrificial anode showed uniform corrosion in seawater environment, but severe non-uniform corrosion in sea mud environment, and the surface corrosion pits were loose porous honeycomb. In the sea mud environment, the corrosion products of the Al-Zn-In-Si sacrificial anode are difficult to diffuse, the corrosion pits appear locally, and the self-corrosion rate is high, resulting in the decrease of electrochemical efficiency. In the dissolution process, the self-consumption increases due to tissue abscission, The decrease of electrochemical capacity leads to the lower electrochemical performance of anode in simulated sea mud than that in seawater environment, and reveals the corrosion mechanism of anode in simulated seawater and mud environment.