Electrochemical corrosion behaviors of Ti3SiC2/Cu composites in a 3.5% NaCl solution

The electrochemical corrosion behaviors of Ti3SiC2/Cu composite and polycrystalline Ti3SiC2 in a 3.5% NaCl medium were investigated by dynamic potential polarization, potentiostat polarization, and electrochemical impedance spectroscopy. The polycrystalline Ti3SiC2 was tested on the identical condition as a control. The characterizations of XRD, X-ray photoelectron spectroscopy, scanning electron microscope, and energy-dispersive spectrometer were used to study the relevant passivation behavior and corrosive mechanism. The self-corrosion current density of Ti3SiC2/Cu (6.46 x 10(-6) A/cm(2)) was slightly higher than that of Ti3SiC2 (1.64 x 10(-7) A/cm(2)). Under open circuit potential, the corrosion resistance of Ti3SiC2/Cu was better than that of Ti3SiC2. Ti3SiC2/Cu exhibited a typical passivation feature with a narrow passivation interval and a breakdown phenomenon. The better corrosion resistance of Ti3SiC2 was due to the more stable Si layer of the former. In comparison, for Ti3SiC2/Cu composites, Cu reacted with the reactive Si layers in Ti3SiC2 to form Cu-Si compounds and TiC, destroying the weak interaction between Si layers and Ti-C layers. In the other hand, the as-formed Cu-Si compounds and TiC dissolved during the corrosion of Ti3SiC2/Cu in the 3.5% NaCl medium, causing to the destruction of the passivation film on its surface.