[Thermal behavior of gypsum bonded investments. (Part I) Thermal behavior in heating process(author's transl)].
The cause of the three shrinkages in the thermal expansion curves of gypsum bonded investments, which were characterized in the previous study, was examined mainly by means of TG-DTA method, X-ray diffraction method and SEM observation. The main results were as follows: 1. The first shrinkage between 100 degrees C and 200 degrees C was caused by the dehydration of gypsum. 2. The second shrinkage between 300 degrees C and 400 degrees C was due to the transformation of soluble anhydrite to insoluble anhydrite. 3. The third shrinkage beginning at the temperature range 700 degrees C approximately 800 degrees C is considered to be related to the sintering of insoluble anhydrite.
D000812:Anhydrides; D002133:Calcium Sulfate; D003734:Dental Casting Investment / Q000592:standards*; D006358:Hot Temperature; D014961:X-Ray Diffraction
D000812:Anhydrides; D003734:Dental Casting Investment; D002133:Calcium Sulfate