Effect of graphitization on the kinetics and mechanism of thermal oxidation of carbon microcoils
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摘要: 以乙炔为碳源，镍粉为催化剂，噻吩为助催化剂，采用化学气相沉积法制备微螺旋炭纤维;在氩气气氛中，2500℃下对所制微螺旋炭纤维进行石墨化处理。通过扫描电子显微镜观察微螺旋炭纤维的螺旋形貌和微观结构，用热重法研究微螺旋炭纤维的耐氧化性能，并探讨了微螺旋炭纤维的氧化动力学行为。结果表明：石墨化处理对微螺旋炭纤维具有显著的纯化作用，其螺旋形貌基本保持不变。微螺旋炭纤维的氧化反应较好地服从一级反应。微螺旋炭纤维石墨化前后的氧化反应活化能分别为263.004kJ/mol和297.191kJ/mol。石墨化处理明显提了微螺旋炭纤维的抗氧化性能。Abstract: Carbon microcoils were prepared by catalytic chemical vapor deposition, using acetylene as carbon source, Ni powder as catalyst, and a sulfur-containing compound (thiophene) as growth promoter. The microcoils were graphitized under an argon atmosphere at 2 500 °C. The morphology and microstructure of the oxidized carbon microcoils were investigated by scanning electron microscopy, and their oxidation resistance was studied by thermogravimetric analysis. Results reveal that oxidation resistance of the carbon microcoils is improved through graphitization, and the graphitized carbon microcoils retain their microcoil morphology after oxidation. Oxidation is a first order reaction and the activation energies are 263 and 297 kJ/mol before and after graphitization, respectively.
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Key words:
- Carbon microcoils /
- Thermal oxidation /
- Kinetics
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