Combustion synthesis of vanadium borides

▶ A comparative study on the preparation of various V–B compounds (including V 3B 2, VB, V 5B 6, V 3B 4, V 2B 3, and VB 2) was firstly conducted by the SHS process. ▶ Sustainability of solid state combustion depended strongly on the starting stoichiometry and preheating temperature of the reactant compact. ▶ Variations of the combustion temperature and flame-front velocity with sample stoichiometry were presented. ▶ The phase composition of the final products was examined and the associated activation energy was determined. An experimental study on the preparation of various vanadium borides (including V 3B 2, VB, V 5B 6, V 3B 4, V 2B 3, and VB 2) in the V–B system was conducted by self-propagating high-temperature synthesis (SHS) from the elemental powder compacts. Close flame-front velocities and comparable combustion temperatures were observed for the reactant compacts with V:B = 1:1, 5:6, and 3:4, and they were much higher than those for the samples of other compositions. The lowest combustion velocity and temperature were detected in the sample of V:B = 1:2. According to the XRD analysis, pure VB was produced not only from the sample of V:B = 1:1, but also from those of V:B = 5:6 and 3:4. For the powder compact with V:B = 1:2, VB 2 was dominantly formed along with trivial amounts of VB and V 3B 4. A multiphase product composed of VB and V 3B 4 at comparable quantities was yielded from the sample of V:B = 2:3. The only V-rich sample formulated at V:B = 3:2 generated monoboride VB and left the end product a large amount of unreacted vanadium.