Setting and Thermal Reactions of Phosphate Investments

The setting reactions and thermal degradation of the phosphate binders are interpreted from the DTA and X-ray diffraction data. Setting takes place through complex formation of (NH4Mg PO4.6H2O)n, excess reactants, and water. Dehydration and thermal reactions lead to a sequence of reactions forming (NH4MgPO4.H2O)n, (Mg2P2O7)n, Mg2P2O7, and Mg3(PO4)2.