The Synthesis and Mechanism of AlB2-KAlF4 Composites Prepared by Self-Propagating High Temperature Synthesis Method

Using Al and KBF 4 as raw materials, AlB 2 -KAlF 4 composites were synthesized by self-propagating high temperature synthesis method. The phase composition and morphology of the composites were investigated and its mechanism was revealed. The results show that the phases of the combustion synthesized product of the Al-KBF 4 system are AlB 2 and KAlF 4 , in which AlB 2 is a hexagonal cylinder, and KAlF 4 has two morphologies: a tetragonal cylinder and a hollow needle-shaped leaf particle. The combustion synthesis reaction of the Al-KBF 4 system begins with the successive melting of KBF 4 and Al. With the increase of temperature, KBF 4 decomposes to form liquid phase KF and gas phase BF 3 . Subsequently, the gas phase BF 3 reacts with the liquid phase Al to form B and AlF 3 , then, AlF 3 reacts with KF to produce KAlF 4 . Finally, the reduced B reacts with the remaining Al to produce AlB 2 .