Phosphate binder refers to an inorganic material with acid orthophosphate or polycondensed phosphate as the main compound and has gelling properties. It is a refractory binder formed by the reaction of phosphoric acid with oxides or hydroxides or alkalis. The combination of phosphate binders is chemical reaction combination or polymerization combination. Most of the binders formed by the reaction of phosphoric acid with alkali metal or alkaline earth metal oxides and their hydroxides are air-hardening binders, that is, condensation and hardening can occur without heating at room temperature. Most of the binders produced by the reaction of phosphoric acid with amphoteric oxides and their hydroxides or acidic oxides are thermosetting binders, which must be heated to a certain temperature to react before they can condense and harden. Phosphate is used as a binder for refractory materials and has strong bonding strength in the middle and low temperature range before ceramic bonding, so it is widely used as a binder for amorphous and unburned refractory materials.