Investigation Of The Pilot-plant Test Of Electrical Silicon Carbon By Multi-thermal Source And Multi-direction Current

At the present time, the industrial method to produce electrical silicon carbon is only Acheson process. Acheson process is very sophisticated after over one hundreds years' development and perfection. But electrical silicon carbon synthesized by Acheson process is of high power consumption, low yield, low-grade and high-cost. The technology of Multi-thermal source comes into mature through small-scale tests, pilot-plant tests in the lab and commercial tests,and is used widely in SiC industry. The essence of the technology is multi thermal sources supply heat for chemical reaction instead of single thermal source. The heat is evenly distributed, the temperature gradient is reduced, the thermal field become uniform in furnace by using the technology. For the alternation of thermal parameter, the diffusion force is reinforced, the capability of exhaust impurity is intensified, and the area of temperature fit for the growth of silicon carbon crystal is larger in furnace. The production synthesized by the technology is of low power consumption, high yield, high-grade. The dominance of Multi-thermal source is very obvious in the synthesis of silicon carbon. Up to date, the technology is not used in the synthesis of electrical silicon carbon for many reasons. The application of the technology is of important purpose. Utilizing existing facilities in laboratory, the pilot-plant tests of electrical silicon carbon of single thermal source and multi thermal source are successfully accomplished by the technology. The influence of synthetic method, technical process, the space length of thermal source and surface power loading to synthesis are investigated in the process of experiment. On the basis of heat transfer, heat transfer equation in single thermal source furnace is solved by analysis. Utilizing a temperature superposition method, the temperature of area affected by multi thermal source is obtained. According to the distribution of heat and mass in furnace, the temperature area in furnace is divided into crystal zone, reaction zone and preheating zone, and the equation of different area is obtained. Analyzing the heat transfer in furnace at power-on terminal phase, the number model of thermal source is established according to conservation of energy principle. The model is proofed by industrial practice, and is of good practicability. The method to determine the number of thermal source is perfected. On the basis of numerical calculation, the temperature field in the furnace is simulated by ANSYS sorft ware. The alteration of temperature, heat flow rate per unit area and temperature gradient of the characteristic points on characteristic line were investigated to get the rule of temperature, heat flow rate per unit area and temperature gradient in furnace. The product synthesized by single thermal source and multi thermal source was detected by the means of XRD and SEM. The result indicated the product synthesized by multi thermal source contain more SiC crystal, the uniformity of crystal type and the pattern of crystal are better than the product synthesized by single thermal source. The result of new material process and roasting material process indicate roasting material process is of absolutely dominant. The space distant of thermal source and surface power loading can affect the result of synthesis. The suitable space distant of thermal source and surface power loading are selected in the industrial production.