THERMAL EFFECT OF A ROUGH CRUCIBLE ON CRYSTAL-GROWTH FROM THE MELT

Experiments have shown that the roughness of the crucible has to be taken into account in order to explain precisely the thermal behaviour of a solidification experiment. We develop an analytical expression in the case of a machined threading roughness and clarify the effect of the main parameters on the thermal transfer. These results are confirmed by numerical simulations of the problem. We show that it is possible to design the roughness in order to get a minimal thermal exchange between the crucible and the sample. Generally speaking, the roughness has a beneficial effect on important growth parameters like solid/liquid interface curvature or radial thermal gradients.