Improving the Na2SO4-induced corrosion resistance of Ti3AlC2 by pre-oxidation in air

Ti3AlC2 suffers severe Na2SO4-induced corrosion attacks at temperatures higher than 800 °C in air. A convenient and efficient pre-oxidation method is proposed to enhance the corrosion resistance of Ti3AlC2. The corrosion weight-changes of the pre-oxidized samples were decreased by about four orders of magnitude compared with those of the untreated specimens. The mechanism on improvement of corrosion resistance was investigated by means of thermogravimetric analysis, X-ray diffraction and scanning electron microscopy/energy-dispersive spectroscopy. A continuous and adherent α-Al2O3 scale was prepared by high-temperature pre-oxidation treatment in air. The preformed dense Al2O3 scale has good compatibility with the Ti3AlC2 substrate, and consequently, can act as an efficient barrier against corrosion. Long-time corrosion tests demonstrate that the Al2O3 scale conserves after corrosion attack and is capable of long-term stability.