Electrochemical corrosion behavior of micrometer-sized porous Ti3SiC2 compounds in NaCl solution

The electrochemical corrosion behavior of reactively synthesized porous Ti3SiC2 in 1 M NaCl solution was investigated compared with that of porous TiAl. Porous Ti3SiC2 and TiAl have high-purity single phase characteristics with open porosities of 48% and 41% and maximum apertures of 6.9 and 16.3 mu m, respectively, which show positive direction shift behavior of open circuit potential at the early immersion stage with stable potential ranges of 0.25 similar to 0.27 and -0.36 similar to-0.38 V (vs. saturated calomel), respectively. The electrochemical corrosion procedures of the two porous compounds exhibit three-stage characteristics of activation, passivation, and breakdown. Porous Ti3SiC2 has a much larger ohmic resistance and Warburg coefficient than TiAl. The passivation films of the two porous compounds consist of an inner layer with a larger resistance and a porous outer layer. Porous Ti3SiC2 has a significantly larger resistance and relatively smaller capacitance for the inner passivation film, indicating better corrosion resistance stability.