Investigation of the Effects of SIMA Process on Microstructure and Electrochemical Behavior of Zn Sacrificial Anode in Simulated Sea Water

Zinc and its alloys have been recognized as sacrificial anodes due to being widely used in cathodic protection systems. Problems caused by the high vapor pressure of this metal in the process of melting and casting have caused that reform processes of the microscopic structure in the solid state for zinc attract a lot of attention. Strain-induced melt activation (SIMA) process is one of the semi-solid forming processes in the production of parts with non-dendritic structure. In this study, the effect of SIMA process on microstructure and electrochemical behavior of zinc sacrificial anode has been examined. The samples were placed under the strain rates of 20-50%, different temperatures in the range of 425-435C and time periods of 10-40 minutes. Optimal spherical microstructure was obtained in 50% cold work conditions, temperature of 430C and 10 minutes. The results obtained from the polarization test and anode test on the optimal spherical sample indicate a tangible reduction in electrochemical corrosion current density by 90% and a slight decrease in anode efficiency compared to the raw sample. Elemental analysis (EDX), metallography images and microhardness profile show the concentration of alloying elements on grain boundary and turning of uniform corrosion into localized corrosion and thus reduced anode efficiency after SIMA process.