Synthesis and oxidation resistance of V 2 AlC powders by molten salt method

Herein, ternary carbide V 2 AlC was synthesized by molten salt method from elemental powders with molar ratio of V:Al:C=2:1.2:1 and same mass of NaCl. According to thermal analysis of the starting mixture, at 800°C, NaCl melts to form ionic liquid environment for the formation reaction of V 2 AlC, which starts at the temperature above 1050°C. The existence of NaCl in starting mixture results in the synthesis of V 2 AlC at 1050°C. And following annealing at 1400°C can remove the impurities of Al 23 V 4 and C to synthesize pure V 2 AlC. Without NaCl, V 2 AlC cannot be synthesized at 1050°C and V 2 AlC synthesized at 1400°C is not pure. For the purpose to measure oxidation resistance of V 2 AlC samples, as‐synthesized V 2 AlC powders were pressed to cylinder shape (Φ10 mm×2 mm) and the cylinders (relative density of 82.7%) were heated in air. At temperature below 400°C, the oxidation was not obvious. At 650°C, a rough film composed of V 2 O 5 and Al 2 O 3 was formed and cover the surface of V 2 AlC. The film resulted in good oxidation resistance of V 2 AlC. At 800°C, the rough film transformed to needle‐like crystals, which were mainly composed of V 2 O 5 . The oxidation resistance became very bad. V 2 AlC can be completely oxidized to form V 2 O 5 and Al 2 O 3 .