Synthesis of low-oxygen Ti₃AlC₂ powders by hydrogenation–dehydrogenation and deoxidation from titanium scraps

The MAX phase is a material with excellent electrical and thermal conductivity and thermal shock and oxidation resistance owing to its metallike bonding properties. The impurities in the Ti₃AlC₂ MAX phase must be controlled because the oxides and TiC derived from the synthesis process remain in MXene and markedly affect the electrical conductivity and chemical stability. This study investigated whether the Ti₃AlC₂ MAX phase can be synthesized from titanium powder prepared from low-cost titanium scrap by hydrogenation–dehydrogenation (HDH) and deoxidation in the solid-state (DOSS) processes. Almost single-phase Ti₃AlC₂ MAX phase was obtained by synthesis at 1450°C for 5 h. The oxygen concentrations of the HDH-MAX and DOSS-MAX powders (25–45 μm) were 7215 and 3875 ppm, respectively. Oxygen reduction of titanium powder through DOSS can help improve the purity of Ti₃AlC₂ MAX phase by minimizing the imbalance in the stoichiometric ratio during synthesis. The HDH-MAX and DOSS-MAX powders prepared from titanium scrap displayed a higher Ti₃AlC₂ phase fraction and lower oxygen concentration than those of commercial Ti₃AlC₂ MAX phase powders. This cost reduction and purity improvement will increase the accessibility of the Ti₃AlC₂ MAX phase, supporting further research into its applications.