Influence of Minor Ag on Electrochemical Corrosion Behavior of Sn-9Zn Alloy

Electrochemical testing, scanning electron microscopy (SEM) observation, energy spectrum analysis were used to study the influence of minor Ag addition on the electrochemical corrosion behavior of Sn-9Zn alloy in 3.5wt.% NaCl solution. The results indicate that the galvanic corrosion reaction in the Sn-9Zn alloy was uniform due to its uniform microstructure. As the anode of the galvanic corrosion reaction, Zn phase almost completely dissolved and reacted in the Sn-9Zn alloy surface. Ag-Zn intermetallic compounds (IMCs) appeared in the Sn-9Zn alloy added with 0.5wt% Ag. An uneven composition and microstructure of the Sn-9Zn-0.5Ag alloy resulted in the galvanic corrosion reaction lopsided and uneven. The corrosion potential shift slightly, and another galvanic corrosion reaction using Sn-rich phase as anode and Ag-rich phase as cathode occurred.