Phosphate bonded castable main materials are phosphate or poly phosphate binder, refractory aggregate and fines, additives. Phosphate binder can be divided into 2 categories: one is acidic phosphate binder, such as Al(H2PO4)3, H3PO4, which is usually used as neutral or acidic refractory material binder, for example, as the binder of silica castable, clay castable, high alumina castable, corundum castable, zircon mullite castable, zircon corundum castable, etc. The other is poly phosphate binder, such as NO5P3O10, (NaPO3)6, which are mainly used as basic refractory castable binder, such as magnesia castable, magnesia alumina castable and so on.

1. Acidic Phosphate Bonded Castable

Acidic phosphate bonded castable will not or slowly react with acidic or neutral refractory material, so coagulation and hardening function is realized by adding coagulator which will react with acidic phosphate. Coagulator can be used are MgO, CaO·Al2O3, CaO·2Al2O3, NH4F, ZnO, Nacl, talc and so on. But the most often used coagulators are MgO and CaO·Al2O3.

Al(H2PO4)3 bonded castable physiochemical index

Acidic phosphate bonded castable applications

Compared with calcium aluminate cement bonded castable, acidic phosphate bonded castable has better cold compression strength and thermal shock resistance, so is usually used as industrial furnaces linings and middle temperature abrasion resistant linings where temperature fluctuation is frequent, it is also used as thermal patching material.