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Analysis of influence factors on performance of graphite crucible

  The graphite crucibles were prepared with flake graphite, silicon carbide, silica and kaolin. The influence factors on the properties of samples were investigated. The results show that, with the increase of the silicon carbide content, the volume density of samples increases, the porosity decreases, the weight loss rate of the sample reduces and the antioxidant activity improves. Elevating the oxidation temperature and prolonging the oxidation time increase the weight loss rate of the sample, decrease the antioxidant activity. The microstructure analysis show that the compactness of the samples rises when the silicon carbide content and the sintering temperature increase.

  The numerical simulation results show that the electromagnetic force and the flow distribution induced by the melt surface are significantly different when the coil position is different. When the coil is located at the upper side of the melt side, the induced electromagnetic force and flow are mainly concentrated in the upper part of the melt, and in the actual production and experiment, it is easy to appear the splash of liquid droplets, and increase the risk. The top of the air and the side mold respectively the heat conduction rate of the melt during solidification process are different. Therefore, when the coil is located at the upper side of the melt side, the precipitation of the grains on the top and side of the melt will occur in time, and the effect of the magnetic oscillation will be affected. And the free grains will move to a long distance to form the solidification structure and increase the possibility of melting the high temperature melt. The coil is located in the side of the lower part of the melt, induction of electromagnetic force and flow distribution in the melt can lower precipitation oscillation impact melt grain side and the bottom of the mold and the heat conduction and the bottom side of the melt rate, grain precipitation at the same time will be better vibration shock effect, nucleation rate get increased significantly. In addition, with the flow of the grain can be directly deposited on the bottom of the melt solidification structure refinement, reduce the high temperature melt melted in free process, the grain refinement effect will be better than in the upper part of the side of the coil.