Formation of V2AlC MAX phase by SHS involving magnesium reduction of V2O5

Abstract

Herein, the V2AlC MAX phase was prepared by self-propagating high-temperature synthesis from V2O5/Mg/Al/C mixtures in molten NaCl salt and acid leaching of the as-synthesized product. The combustion process was performed in a stainless-steel chamber in the graphite boat under an argon atmosphere of 3 MPa. X-ray diffraction analysis was used to examine the phase composition of the products. During combustion synthesis, a multiphase powder product containing V2AlC, VAl, VC and MgO, MgAl2O4 is formed. By adjusting the ratios of the initial materials, we determined that 26.6V2O5/28.2Mg/4.5Al/0.7C/40NaCl mixture resulted in the maximum V2AlC yield without spinel impurity. The following acid leaching leads to the removal of VAl impurity and obtaining of a powder containing up to 95% V2AlC. According to SEM analysis the powder is composed dominantly of flake-like grains. Thus, the choice of the available and low-cost precursor materials and the use of the energy-efficient SHS method allow for a drastic reduction in the production cost of the V2AlC.