Kinetics of Synthesis of Silicon Carbide through Carbothermal Reduction of Silicon Oxide

• Main Authors: Chen, Chih-yung, 陳智勇
• Other Authors: Lin Chun-I
• Format: Others
• Language: zh-TW
• Published: 1997
• Online Access: http://ndltd.ncl.edu.tw/handle/94220456840643778964

碩士 === 國立台灣工業技術學院 === 化學工程技術研究所 === 85 === The kinetics of synthesis of silicon carbide through carbothermal reduction of silicon dioxide has been studied in our experiment. X-ray diffraction analysis were employed to determine the content of products. The effects of several parameters on the reaction rate were obtained. Experimental results indicated that the reaction rate could be increased by decreasing the flow rate of He, the SiO2/C ratio, the grain size of silicon oxide or carbon and the initial density of solid sample. The rate could also be increased by increasing the height of solid sample and the reaction temperature. It was also found implicitly that SiO was an intermediate product. The activation energy of the production of β-SiC was found to be 436kJ/mole. Following are the empirical rate expressions of conversions of carbon, silicon oxide and production of silicon carbide obtained by regression of the experimental data： dCc-rc = - -------- = 7.6E4 *exp(-412,132/RT) *dsio2^(-0.742)* dc^(-0.549) dt *Csio2^(0.308)* Cc^(0.316)*Csic^(-0.046)*D^(-0.218) *f^(-0.311)*h^(0.460) dCc-rsio2 = - ------ = 1.2E4 *exp(-401,513/RT) *dsio2^(-0.801)*dc^(-0.392) dt *Csio2^(0.476)*Cc^(0.283)*Csic^(-0.077)*D^(-0.241) *f^(-0.304)*h^(0.412) dCsicrsic = -------- = 2.5E4 *exp(-436,012/RT) *dsio2^(-0.474)*dc^(-0.315) dt *Csio2^(0.407)*Cc^(0.328)*Csic^(0.013)*D^(-0.234) *f^(-0.352)*h^(0.414) The applicable range of the empirical rate expressions are flow rate of He 1x10-5 - 5x10-5 m3/s, sample height 0.007 - 0.020m, reaction temperature 1,573 - 1,773K, SiO2/C molar ratio 1/5 - 1/1, grain size of silicon oxide 0.000042 - 0.000113m, grain size of carbon 0.000051 - 0.000134m and initial bulk density 339.5 - 577.2kg/m3.