The crystallization of a molten sphere

The crystallization process of a molten sphere supported at the end of a rod of the same material was studied, when the heat source is slowly withdrawn. As only one solidification front exists and new material is not added to the system, the shape is not coupled to the thermal problem which simplifies the solution of the whole problem. Quasi-steady quasi-onedimensional heat transfer models are used to describe the solidification front dynamics. Theoretical and experimental results are compared, showing good agreement. Therefore, the crystallization of a sphere, with the theoretical support presented here, seems to be a good method for the determination of the receding contact angle at an advancing solidification front of any kind of crystal. The shape problem solution can be used to evaluate the thermal models developed for other heating or cooling systems. The simplified thermal model developed here for the mirror furnace could be used by an experimenter to predict both the power and the pulling rate laws required to achieve a specified growth rate profile in the sphere solidification process.