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以天然气为碳源,氢气为载气,通过无催化化学气相沉积的方法,合成不同粒径的球形炭。研究了沉积温度、压力和气体比例对化学气相沉积球形炭的影响。用X射线衍射、扫描电子显微镜和透射电子显微镜对实验结果进行表征。研究结果表明制备纳米球形炭(50~100 nm)的优化工艺为沉积温度1150℃、沉积压力5kPa和天然气/氢气(气体流量比)1∶4。本研究对球形炭的气相沉积机理进行了详细的研究。沉积温度对球形炭的尺寸和微结构影响较小,沉积压力对炭核的碰撞几率影响较大。另外,氢在炭形核过程中起来很重要的作用,氢的存在有效的较少了炭核的碰撞几率。
Using natural gas as carbon source and hydrogen as carrier gas, spherical carbons with different particle sizes were synthesized by catalytic chemical vapor deposition. The effects of deposition temperature, pressure and gas ratio on the spherical carbon by chemical vapor deposition were investigated. The experimental results were characterized by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The results show that the optimal preparation process for nanoscale spherical carbon (50-100 nm) is deposition temperature 1150 ℃, deposition pressure 5 kPa and natural gas / hydrogen (gas flow ratio) 1: 4. In this study, the vapor deposition mechanism of spherical carbon was studied in detail. The deposition temperature has little effect on the size and microstructure of spherical carbon, and the deposition pressure has a great influence on the probability of collision of carbon nuclei. In addition, hydrogen plays a very important role in the carbon-based nucleation process. The presence of hydrogen effectively reduces the probability of carbon-carbon collisions.