The alumina bubble is a hollow spherulitic heat-insulating material, which is made by electro-fused method. It is noted for its low-density, heat-resistance, close pore. The melting point is around 2100℃.

It is an ideal filler for high-temperature furnaces and and an excellent aggregate of lightweight castable refractory. And it is an ideal heat-insulating and energy-saving refractory in high temperatures. Bubble Alumina exhibits high creep resistance to temperatures as high as 1825°C. Widely used in petrochemical industrial gasification furnace, carbon black industry reaction furnace, induction furnace in metallurgical industry and high temperature, ultra-temperature furnaces, especially as the lining, can achieve a good energy saving effect.