Combustion synthesis of CaB6 powder from calcium hexaborate and Mg

Abstract

Abstract As one of the important metal-borides, calcium hexaboride (CaB 6 ) is applied in refractory materials, metal deoxidant, neutron absorbent, wear-resisting agent and functional ceramic materials. Generally, CaB 6 is produced from B 4 C or B 2 O 3 which is obtained at high temperature and high cost. In this study, the CaB 6 powder was prepared through combustion synthesis by using calcium hexaborate and magnesium as starting materials. The calculated adiabatic temperature of CaB 6 O 10 –Mg system reached 2406.69 K. The XRD analyses of combustion products showed that there existed a small amount of Mg 3 B 2 O 6 and Ca 3 (BO 3 ) 2 besides CaB 6 and MgO. The XRD patterns of products leached by HCl indicated the major part of the leached sample is comprised by CaB 6 , showing that MgO and by-products were efficiently leached out. In addition, the technological conditions for combustion synthesis were investigated. It is resulted that larger particle size of CaB 6 O 10 and higher compacting pressure is beneficial to the production of CaB 6 .