MICROSTRUCTURE AND GROWTH MECHANISM OF SiC WHISKERS SYNTHESIZED BY CARBOTHERMAL REDUCTION OF SILICON NITRIDE

摘要

SiC whiskers were synthesized at 1500℃ under argon atmosphere by using Si_3N_4, active carbon and B_2O_3 powders as starting raw materials. The morphology and crystal structure of the synthesized SiC whiskers were characterized by scanning electron microscope, transmission electron microscope and selected-area electron diffraction, respectively. The growth mechanism of the synthesized whisker was discussed. The results show that the synthesized SiC whiskers are β-SiC with the characteristics of single crystal, growing along direction. Two main kinds of morphology are observed, one with the perfect of single crystal growth and the other with obvious stacking faults or micro twins. VS mechanism is the main growth mechanism of SiC whiskers by carbothermal reduction of silicon nitride in this work.