This study investigated the impact of NaCl concentration on the electrochemical performance of one kind of commercial Mg-Mn alloy （M1C）. Firstly, potentiodynamic polarization （PDP） tests were conducted to determine corrosion behavior of M1C in NaCl solutions with concentrations of 0.1 mass％, 0.5 mass％, 3.5 mass％, and 10.0 mass％. Additionally, electrochemical impedance spectroscopy （EIS） tests were performed to analyze the oxide film thickness across varying solution concentrations. The PDP results indicated that the corrosion rate of M1C increased with the increase of solution concentration. Furthermore, breakdown potential was observed in anodic polarization curves when the concentration of NaCl solution was over 0.5 mass ％. The EIS results showed that after 24h immersion, thickness of MgO film decreased with increasing NaCl concentration and then stabilized.

The corrosion resistance of WC-Ni-Cr-Mo cemented carbides in aqueous NaCl solutions at various pH values has been investigated by electrochemical measurements, surface observation and solution analysis. In acidic environments, WC passivates and binder metals selectively dissolve. In neutral environments, Cr and Ni passivate at corrosion potential and lower potentials than 0.5 V and WC either passivate or dissolve at a slower rate, while transpassive dissolution of Cr in the binder and dissolution of W occurs at potentials higher than 0.5 V. In a basic environment, the dissolution behaviour of the WC-Ni-Cr-Mo alloy is similar to that in a neutral environment, however, the dissolution of WC occurs significantly with increasing anodic potential from corrosion potential.