Phosphate bonded high alumina brick is a kind of chemical bonded refractory brick, which is made of phosphoric acid solution or aluminum phosphate solution (such as aluminum dihydrogen phosphate, PA-80 glue, etc.) as binder, bauxite clinker as aggregate, machine pressed and processed at 500 ~ 600 ℃.
Phosphate combined with high alumina brick, referred to as phosphate brick, while aluminum phosphate combined with high alumina brick, referred to as wear-resistant brick. The latter has higher compressive strength.
The traditional phosphate bonded high alumina brick has two obvious shortcomings: one is the lower load softening temperature, about 1300 ℃; the other is the shorter reheating line, which affects its application effect and scope. In order to deal with this problem, it is an important measure to add three stones to the material. As mentioned before, the three stones can not be changed into mullite and mullite at high temperature, and with the volume expansion, the load softening temperature of the products can be improved, the shortening at high temperature can be reduced, and the thermal shock resistance can be improved.
Phosphate brick is made by pre mixing, blocking, mixing, forming, drying, heat treatment and other processes, with special bauxite clinker as the primary material and proper amount of phosphoric acid aqueous solution added. Phosphoric acid itself has no cohesiveness. When it reacts with neutral oxide and weak alkaline oxide of special grade bauxite clinker to produce phosphate, it shows outstanding cohesiveness.
Phosphate high alumina brick has high strength, good wear resistance and excellent chemical resistance. (its alkali resistance is better than clay brick and high alumina brick), excellent thermal shock resistance and high load softening temperature. Therefore, it is often used in the transition zone of the reverse kiln, the kiln mouth, the kiln door cover, the inner lining of the cooler and other places where the refractory bricks are easy to loose and fall.