[Thermal behavior of gypsum bonded investments. (Part 2) Sintering phenomena of set plaster (author's transl)].
The sintering phenomena of set plaster on the heating process have been investigated by measuring shrinkage and apparent density and by observing the structure of fractured surface with SEM. As a result, it was found that the sintering shrinkage occurred in two stages for the temperature range from 500 degrees C to 900 degrees C. In the first stage between 500 degrees C and 800 degrees C, the skelton of needle-like crystals of gypsum remained and micro-grains were observed in it. In the second stage between 800 degrees C and 900 C, the skelton disappeared and the grain growth was remarkable. In addition, the rate of shrinkage was slow in the first stage, and was very fast in the second stage.
D002133:Calcium Sulfate; D003734:Dental Casting Investment / Q000592:standards*; D006358:Hot Temperature
D003734:Dental Casting Investment; D002133:Calcium Sulfate