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

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 degrees 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 Xray 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 nonstoichiometric TiC0.67 formation.

Automated summary

A nearly monolithic MAX phase material containing 95 wt% Ti3AlC2 and 5 wt% TiCx was synthesized by spark plasma sintering under vacuum conditions. The corrosion behavior of Ti3AlC2 in molten LiCl-KCl salt was investigated, revealing Al dissolution causing delamination of the layered structure and leading to the formation of a Ti3C2Cl2 exfoliation layer. The de-twinning of Ti3C2 layers and formation of nonstoichiometric TiC0.67 may be attributed to the substitution of Cl- anions by O.