Setting and Thermal Reactions of Phosphate Investments

Abstract

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, (Mg2P2 O7)n', Mg2P 2O7, and Mg3(PO4)2.