alumina hollow sphere brick 1.Alumina reach 99.4%,B.D.1.5g/cm3 2.competitive price,has ISO certificate 3.insulation,fireproof alumina ... . Application:1). As lining components for the high temperature industries furnace (above 1800, such as refractory, electronics, ceramics industries).2).As Thermal ... of off-colour industry, electric induction furnace of metallurgical industry. alumina bubble brick