Synthesis and high temperature corrosion behaviour of nearly monolithic Ti3AlC2 MAX phase in molten chloride salt

Abstract

Nearly monolithic MAX phase containing 95 wt.% Ti3AlC2 and 5 wt.% TiCx was synthesized by spark plasma sintering under vacuum sintering conditions. Corrosion behaviour of Ti3AlC2 was investigated in molten LiCl–KCl salt at 600 °C under a dry Ar atmosphere. Evolution of microstructure and surface chemistry of the exposed sample was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and glancing angle X-ray diffraction (GAXRD). Results showed that Al dissolution led to delamination of the layered structure which favoured the ingress of chlorine and its subsequent intercalation into the Al–site plane to form a Ti3C2Cl2 exfoliation layer. De-twinning of the Ti3C2 layers possibly due to Cl− anions substitution by O results in non-stoichiometric TiC0.67 formation.