Graphitization at low temperatures (600-1200 掳C) in the presence of iron implications in planetology

详细信息    查看全文

• 作者：E. Charon ; J.-N. Rouzaud ; J. Al茅on
• 刊名：Carbon
• 出版年：January, 2014
• 年：2014
• 卷：66
• 期：Complete
• 页码：178-190
• 全文大小：3025 K

文摘

Our objective is to understand how graphite can be formed at 鈥渓ow鈥?temperatures (<1200 掳C) in contrast to the high temperature of the industrial processes (鈭?000 掳C), and from precursors which are non-graphitizable by a thermal treatment alone. Blends of iron and saccharose char were heated between 650 and 1600 掳C. The carbons obtained were characterized by SEM, TEM and Raman microspectrometry. Our work confirms that graphite can be formed from non-graphitizable carbons during a heat-treatment in the presence of iron. Carbon and iron migrations, below the eutectic temperature (1150 掳C), appear to be a key factor for carbon transformation. Iron migration and graphitization could be favored by nucleation of Fe nanoparticles and surface melting, detected as soon as 900 掳C. This allows formation of turbostratic macroporous carbons. Above the eutectic, all iron is liquid and graphitization occurs; it is complete at 1600 掳C. Heat-treatment duration, observed over 4 orders of magnitude, favors the structural improvement. Concerning applications in planetology these experimental samples are pertinent experimental analogues of natural carbons from differentiated parent-bodies (with an iron core), and explain how graphite can be formed at temperatures below 1200 掳C in these environments.