Synthesis of h-BN composite powders via aluminothermic reduction combustion route

h-BN composite powders were prepared by an aluminothermic reduction combustion synthesis route using a mixture of B2O3 and Al as raw material, and MgO as diluent under low-pressure nitrogen (.6 MPa). The phase transformation and structural evaluation during the combustion synthesis were investigated. Samples with B2O3 to Al molar ratio of 1:6 exhibited the highest diffraction peaks of h-BN, in which the phases are h-BN, Al2O3 & BULL;7AlN, AlN, and MgAlON spinel phase. The combustion wave quenching test revealed that h-BN is mainly formed via following routes: first, Al reacts with nitrogen; then the resulting AlN reacts with B2O3 to form h-BN. Due to solid solution formation between Al2O3, AlN, and MgO, both MgAlON and Al2O3 & BULL;7AlN were formed in the resulting samples. The composite powders obtained by aluminothermic reduction combustion synthesis in this work exhibit potential application in refractories industry for replacing graphite in carbon-containing refractories. h-BN composite powders were combustion synthesized via aluminothermic reaction. Product with B2O3 to Al molar ratio of 1:6 exhibited highest h-BN diffraction peaks. Nitriding of Al formed AlN and release heat maintaining the reaction forming h-BN. h-BN was mainly formed via the reaction between AlN and B2O3. The h-BN composite powder can be used as substitution for graphite in refractories.image