抄録
The application of microwave heating for drying gypsum molds was studied. Alpha-gypsum and permeable plaster were used as mold materials. Alpha-gypsum mold could not be completely dried when it was not heated to over 200°C. The alpha-gypsum mold with which Fe3O4 or graphite powder was mixed, could be heated to over 200°C in a few minutes, and dried perfectly within ten minutes. Permeable plaster mold had the same tendency as alpha-gypsum mold: permeable plaster mold, with which Fe3O4 was mixed, was heated rapidly and dried completely. The effect of Fe3O4 or graphite powder is in that they are extremely sensitive to microwave energy (2,450MHZ). Gypsum mold, into which Fe3O4 was mixed, was low in viscosity, appropriate in hardening period and had sufficient compression strength. In conclusion, gypsum mold was heated rapidly in a microwave oven after adding a microwave-sensitive powder such as Fe3O4. For instance, the mold (145×185×100 mm3) with which 10 wt% Fe3O4 was mixed, dried perfectly in ten minutes without cracking.
