Electrochemical Formation of MoSi₂ by Controlling Rate of Silicon Transport

Improving the oxidation resistance of refractory materials is essential for improving the thermal efficiency of power generation, thereby reducing CO 2 emissions. In this study, an efficient process of forming oxidation-resistant MoSi 2 films using an electrochemical method by controlling the rate of Si transport was investigated. During galvanostatic electrolysis, a large amount of Si was deposited and protruded outward from the cathode, consistent with the results of a previous study. As electrolysis progressed, the rate of Si diffusion decreased rapidly. Therefore, multistep electrolysis, in which the current density was decreased in a stepwise manner, was conducted. Furthermore, multistep pulse electrolysis, in which the average current density was decreased while maintaining a high applied current density, was conducted. Upon increasing the thickness of the target film, the efficiency of galvanostatic and multistep electrolysis declined, where the highest efficiency for multistep pulse electrolysis was achieved at an average film thickness of 50 μm. Si deposition was effectively inhibited via multistep pulse electrolysis; however, cracking and peeling of the MoSi 2 film were observed due to the difference in the thermal expansion coefficients of MoSi 2 and Mo. Buffering due to the formation of the intermediate-phase Mo 5 Si 3 was expected.