Chemical vapor deposition of C on SiO2 and subsequent carbothermal reduction for the synthesis of nanocrystalline SiC particles/whiskers
Chemical vapor deposition of C on SiO2 and subsequent carbothermal reduction for the synthesis of nanocrystalline SiC particles/whiskers
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DOI：
10.1016/j.ijrmhm.2011.03.005
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发表时间：
2011-09-01
影响因子：
3.6
通讯作者：
Eroglu, S.
中科院分区：
文献类型：
--
作者：
Cetinkaya, S.;Eroglu, S.
本研究研究了甲烷在颗粒二氧化硅上的化学气相沉积以及随后的碳热转化为碳化硅粉末。采用质量测量、高分辨透射电子显微镜、扫描电子显微镜和X射线衍射仪对不同工艺阶段的产物进行了表征。结果表明，在CH4气氛下，氧化物颗粒在1300K时由于增强了C的吸收而迅速增加质量。在SiO_2颗粒表面沉积了厚度为5~8 nm的热解碳层。以C含量为40wt%的包覆粉为原料，在1700~1800K温度范围内，用Ar气流将高C载量(40~42.6wt.%C)的包覆粉转化为碳化硅，在1750K下反应45min，在1800K下反应30min，可得到接近100 nm的纯碳化硅粉末。提出了碳化硅晶须的生长方式为气-固机制。用Gibbs自由能最小化方法进行平衡热力学分析，预测了Si-O-C-Ar体系中生成碳化硅和产物物种的反应途径。研究表明，C壳-SiO_2芯粉和碳化硅微粉均可在同一反应器中快速合成。(C)2011爱思唯尔有限公司。保留所有权利。
This study investigates chemical vapor deposition of C from CH4 on particulate SiO2 and subsequent carbothermal conversion of the resultant composite particles to SiC powders. Mass measurements, HR-TEM, SEM and XRD were used to characterize the products at various stages of the processes. It was found that oxide particles gained mass rapidly at 1300 K under CH4 atmosphere owing to enhanced C uptake. Pyrolytic carbon layers 5-8 nm thick were deposited on SiO2 particles. The coated powders with high C loadings (40-42.6 wt.% C) were converted to SiC under Ar flow in a temperature range of 1700-1800 K. Almost pure SiC powders containing a mixture of particles and whiskers of similar to 100 nm were synthesized at 1750K for 45 min and at 1800K for 30 min using the starting powder with 40 wt.%C. Whisker diameter increased with the C content of the coated powder. It was proposed that SiC whisker was grown by a vapor-solid mechanism. Equilibrium thermodynamic analysis by the method of minimization of Gibbs' free energy predicted the reaction pathways to SiC and to the product species in the Si-O-C-Ar system. This study demonstrated that either C shell-SiO2 core powders or SiC powders could be synthesized rapidly in the same reactor. (C) 2011 Elsevier Ltd. All rights reserved.