CONTROL OF CRYSTALLIZATION OF NON-FERROUS METALS BY CHANGING THE PHASES OF THE SUPPLY CURRENTS OF A LINEAR INDUCTION STIRRER

Abstract

Experiments were performed to study the crystallization of a gallium alloy in a vertical flat rectangular cuvette under external electromagnetic influence. The results of the study show that the propagation velocity and shape of the crystallization front can be effectively controlled by changing the power supply parameters of the electromagnetic stirrer. A mode characterized by intense stirring flow and significant inhomogeneity of the crystallization front was selected by varying the amplitude of electromagnetic forces. In this mode, changing the phase angles of the supply currents of the linear induction machine allows a fundamental change in the topology of hydrodynamic melt flows at a constant power supply of the stirrer. This, in turn, leads to a change in heat and mass transfer characteristics and hence the conditions in the interfacial region, making it possible to indirectly control the homogeneity of the crystallization front and, to a lesser extent, the phase transition rate. The contribution of convection to flow formation and its influence on the crystallization process have been studied. In particular, it has been shown that thermal convection can lead to the formation of additional vortex structures near heat exchangers, which prevents metal crystallization.