Thermochemical and microstructural study of modified CaSO4 bonded investment with inorganic and organic additives

Some chemical-physical properties of gypsum bonded investment are studied as a function of the addition of different inorganic and organic additives as well as of the temperature and duration of burnout process. The attention has been focused on the measurement of the temperature of the CaSO4 thermal decomposition that is strictly related to the origin of gas porosity and on the microchemical and microstructural properties of the thermal treated CaSO4 bonded investment such as porosity and particles morphology. The results evidence the role played by the additives on the final chemical-physical properties of the investment.