摘要
首先以硅溶胶（w（SiO2）=30%,平均粒径为10-20 nm）和活性炭（平均粒径〈10μm,w（C）=99.5%）为原料,六偏磷酸钠为分散剂,混匀后在真空下于110℃烘干24 h制成反应前驱体,然后将其破碎成不同粒度的细粉,在多模谐振腔微波炉中分别加热至1 300-1 600℃保温15-60 min制备了SiC晶须,研究了热处理温度、保温时间以及反应前驱体的粒度对晶须产率的影响。结果表明：（1）当热处理温度为1 300-1 400℃时,产物主要为方石英及少量β-SiC,SiC晶须的产率较低;温度达到1 500℃以后,产物主要为SiC晶须及少量SiC颗粒,且在1 500℃下保温时间从15 min延长到30 min时,SiC晶须产率显著增加;温度提高到1 600℃时,生成了等轴SiC颗粒及SiC晶须。（2）1 500℃保温30 min为比较适合的微波加热合成条件,晶须产率能达到80%以上。（3）较小的反应前驱体颗粒有利于SiC晶须的生成。
The starting materials of silica sol （ w（SiO2） = 30%, average grain size： 30 - 20 nm） and active carbon （average grain size 〈 10 μm, w（C） = 99.5% ） along with the dispersant of sodium hexametahposphate were stirred for homogeneity and dried in vacuum at 110 ℃ for 24 h to prepare the precursors. Then the precursors were crushed into powders with different particle sizes. SiC whiskers （SiCw） were synthesized by heating the precursor powders in a multimode cavity microwave oven at 3 300 -3 600 ℃ for 35 -60 min. The effects of heat treatment temperature, soaking time and particle sizes of the precursors on the productive rate of SiCw were studied. Experiment results showed that. （3） At 1 300 - 1 400 ℃,the products were mainly composed of cristobalite and a little SiCw, the productive rate of SiCw was relatively low. At 1 500 ℃,the products mainly contained SiCw and little SiC particles （SiCk）. When the soaking time was extended from 35 min to 30 min at 3 500 ℃,the productive rate of SiC, increased greatly. SiCw and uniaxial SiCw were synthesized at 3 600 ℃. （2） The optimum condition for synthesizing SiCw was 3 500 ℃ for 30 min and the productive rate of SiCw was higher than 80%. （3） Reactant with small particle sizes was favorable for increasing the productivity of SiCw.
出处
《耐火材料》
CAS
北大核心
2008年第5期357-361,共5页
Refractories
基金
国家自然科学基金资助项目(50472094)
关键词
碳化硅
晶须
微波合成
碳热还原法
Silicon carbide,Whisker, Microwave synthesis, Carbothermal reduction
