Alumina Brick

Alumina brick can be made by electric fused corundum or sintered corundum with traditional refractory ingredients and semi-dry molding and firing process. It can also be made with whole fine powder. When Al2O3 is used for all powder molding, in order to improve the molding performance, "false particles" must be made first. With very fine ground powder added to the binder, to make a good fluidity of the coarser particles. There are several methods for making false granules or granulation:

1. Common Law. An appropriate amount of binder solution was added to the powder, mixed with a coarse sieve, and the granule with uniform particle size was obtained by the cohesion of binder.

2. Pressure method. The powder mixed with the binder is first pressed into blocks, then broken and sifted into coarse grains. Its density and mechanical strength are both high, and it is a common method in industrial production.

3. Light burning method. A small amount of water is used to make the ball into a clay ball, which is calcined at a lower temperature and then broken through the coarse sieve.

4. Spray drying. The paste is made of powder and binder, then atomized by spraying inside the granulator, and the droplets are dried by the hot air inside the tower.

Fired bricks made from fused alumina as the main raw material are called sintered fused alumina bricks or fused fused alumina bricks, which are different from those made from sintered alumina as the main raw material. Alumina hollow ball as the aggregate, alumina fine powder as the matrix made of bricks, called alumina hollow ball brick. A small amount of titanium oxide, magnesium oxide and kaolin are sometimes added to the ingredients as sintering AIDS. Billet forming binder can be used carboxymethyl cellulose, dextrin, aluminum phosphate, aluminum sulfate, water, etc. For example, the ratio of sintered pure corundum bricks is :50%~60% alumina particles (aggregate), 40%~50% alumina fine powder (matrix), plus 7%~8% carboxymethyl cellulose solution with a mass fraction of 2%. After weighing according to the composition of the formula, the blank is evenly mixed in the blender. When mixing, first put the particles into the blender, add 2% binder, mix for a few minutes, then add fine powder and mix for a few minutes, finally add 5% binder, continue to mix for 15 minutes or so before the material comes out. The billet is then weighed into the mold and molded by 60~100MPa pressure on an oil press or friction press. The density of the standard brick shall be greater than 2.0g/cm3.

There are various specifications and shapes of alumina brick products. Such as standard brick, straight brick, axe brick, knife edge brick, banana brick, arch brick, arch brick, burner brick, and various types of brick. According to the chemical composition, there are pure corundum bricks, titanium corundum bricks, chromium corundum bricks, mullite special corundum bricks, carbon corundum bricks, etc., corresponding quality indexes also have certain differences.