稻壳制备碳化硅晶须

Preparation of SiC Whiskers from Rice Husk

通过稻壳先炭化再高温合成两步法制备出碳化硅晶须,考察温度、催化剂、合成气氛和时间对碳化硅晶须形成的影响。采用扫描电子显微镜、透射电子显微镜、X射线衍射对合成的碳化硅晶须进行表征,分析碳化硅晶须形成机理。结果表明:SiC晶须的形成温度不低于1 200℃,在合适的温度范围内,温度越高,SiC晶须的产量越高;1 400℃为适宜的加热温度。在真空条件下无碳化硅晶须生成,通Ar保护和加入催化剂能促进碳化硅晶须的形成和长大。控制时间在2h左右,随着合成时间的延长,碳化硅晶须量增加。碳化硅晶须为竹节状直晶、光滑直晶和弯晶,其中直晶居多,组成为β-SiC。由稻壳制备碳化硅晶须的形成机理制为在催化剂作用下的气-液-固和气-固机理。

SiC whiskers were prepared v/a two-stage carbonthermal reduction with carbonized rice husks. The effect of process condition （i. e. , temperature, catalyst, atmosphere and time） on SiC whiskers formation were investiaged. The SiC whiskers were characterized by scanning electron microscopy, transmission electron microscopy and X-ray diffraction, respectively. The formation mechanism of SiC whiskers was discussed. The results indicate that the formation temperature of SiC whiskers is not lower than 1 200 ~C. The high productivity of SiC whiskers can be obtained when the temperature increases. SiC whiskers are not formed in vacuum and synthesized in Ar protection with catalysts. The SiC whiskers increase with increasing the reaction time during 2 h. The SiC whiskers appear barnbcx〉like straight, smooth straight and bent. The straight whisker is the major morphology product. The formation of SiC whiskers are due to the vapour-liquid-solid and vapour-solid mechanism with catalyst~