As reactors,coke and quartz sand are added,and silicon carbide powder with different grain size was prepared by microwave heating method.The effects of reaction temperature(1300-1600 ℃),holding time(15-60 min) and particle size of coke on phase,productivity and particle size of silicon carbide powder were studied.The results show that SiC micro powder can be prepared at 1600 ℃×30 min and the content of SiC can reach 98.1%;SiC powder with 8.6 μm and 156.9 μm of D50 can be got by controlling the size of coke particle.This method has cheap raw materials,simple technology,and it is easy to realize industrialization.

Silicon carbide whiskers were synthesized by microwave heating carbothermic method using dried silica sol and active carbon as reactants under the condition of no adding any metal catalysts.The effects of heating temperature and time on products were studied.The results show that as the sintering temperature rises from 1300 ℃ to 1600 ℃ under the heating time of 30 min,the amount of β-SiC phase in the product increases.Different products are observed at different positions of the crucible.The products of dispersal SiC whisker and agglomerated SiC whisker at the top part and the center part of the crucible,and smooth surface SiO2 particles at the bottom of the crucible are obtained at the sintering temperature of 1500 ℃ for 30 min.Under the condition of heating temperature at 1600 ℃,the synthetic products are mainly composed of dispersal SiC whisker and equiaxial β-SiC particles at the top part and the center part of the crucible,and a mixture of whiskers and particles at the bottom of the crucible.It is found that higher yield and straight whiskers ratio can be obtained for synthesizing silicon carbon whiskers by microwave sintering at 1500 ℃ for 30 min.

Kinetic analysis of silicon carbide prepared by carbon-thermal reduction is introduced in this paper. Through the dynamic analysis, kinetic parameters of Si-C are calculated, and it is estimated that the time required reaction materials of different diameter completely converted to SiC at different temperatures. Reaction time is nearly 1 hour long when the reaction particle diameter is 1μm around 1900K.