Abstract
In order ot investigate the casting shrinkage of the dental alloys, the density of five gold alloys and Au-Pd-Ag alloy were measured at temperatures ranging from room temperature to about 1, 400℃ by using an apparatus which was based on the Sessile drop method and of which the reliability has been confirmed in previous work. The thermal and solidifying shrinkage were discussed on the densisties at room temperature, solidifying point and melting point which were determined from the curves showing the variation of density with temperature. The voluminal shrinkage during solidification of multi-component alloys was smaller than that of small-component alloys and the surface of the former having large dendrites was more smooth than the later having many shrinkage folds was. The growth of the dendritic structure during solidification causes many vacancies in the cast and results the small solidifying shrinkage.
