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 (NH 4 Mg PO 4 .6H 2 O) n , excess reactants, and water. Dehydration and thermal reactions lead to a sequence of reactions forming (NH 4 MgPO 4 .H 2 O) n , (Mg2P2 O 7 ) n ', Mg 2 P 2 O 7 , and Mg 3 (PO 4 ) 2 .