Electrochemical Corrosion Behaviors Of Ti₃AlC₂ And Nb₄AlC₃

Ti3AlC2, an important member in the family of layered ternaries so-called MAX, is a promising material for the application in electrochemical field due to high electrical conductivity as metals and so on. The motivation thus for this work is twofold, scientific and technological. Electrochemical corrosion behaviors of Ti3AlC2 in 1 M NaOH,1 M H2SO4,0.5 M NaCl,1 M HC1 and 1 M HNO3 solutions were investigated by means of electrochemical measurements such as polarization and electrochemical impedance spectroscopy (EIS) in conjunction with Scanning Electron Microscope (SEM) and X-ray Photoelectron Spectroscopy (XPS).Passive behaviors, corrosion kinetics and film formation mechanisms were studied for Ti3AlC2 in H2SO4 and NaOH solutions. The results show that corrosion resistances greatly depend on the "passive" films, by which Ti3AlC2 is leading to totally different corrosion processes. Ti3AlC2 displays good corrosion resistance due to the formation of protective titanium oxides scales that act as passive films both after anodic polarization and immersion in NaOH. It exhibits poor corrosion resistance in H2SO4, on the other hand, for the pseudo-passive films that formed are mainly permeable titanium sub-oxides, which fail to inhibit further erosion of Ti3AlC2 substrate.Additionally, in NaCl and HC1, pit happens due to a very strong influence of the corrosive Cl. Finally, as a result of oxygen evolution at relatively high anodic potentials, local corrosion presents after polarization in HNO3.Preliminary research on the electrochemical corrosion behaviors indicates that Nb4AlC3 is corrosion resistant in H2SO4.