With the development of science and technology, new hollow materials made of glass, ceramic and carbon are widely used in the many science industries.
Refractory products made of hollow spheres have good high temperature resistance, good insulation properties, good thermal shock resistance and high strength. Since those materials have low bulk density and low thermal capacity, they can improve the thermal efficiency of high temperature furnaces, shorten the production cycle and significantly reduce the weight of the furnace. It can be directly used in the linings of high temperature furnaces.
Alumina bubble bricks can be used at 1800℃ for a long time. At high temperature, they have good chemical stability and corrosion resistance. But they can keep stable in a hydrogen atmosphere.
Alumina raw materials are melted in an electric arc furnace at 2200℃. When pouring the melt out, blow the melt with high pressure air to make the melt dispersed into small droplets. During the cooling process, the droplets form alumina hollow balls due to surface tension effects.
The hollow balls are screened to remove fine powder and big fragments and particles. Iron is removed with the magnetic iron. Broken balls are removed with a ball selecting machine. Then the alumina hollow spheres are packed as the finished products.
Alumina bubble bricks are made of 70% alumina hollow spheres and 30% sintered alumina powder, bonded with aluminum sulfate, molded by vibration molding in a wooden mold by applying pressure. After drying, the green body is sintered at high temperature or light burned into bricks.