以井式气体渗碳炉中的碳黑为原料,采用真空热处理法制备了纳米碳洋葱。首先,对原料进行了XRD和HRTEM表征,并对其各种成分的形成原因进行了分析;然后,采用不同的温度(1100~1900℃)对原料进行热处理,得到了单体碳洋葱和内包金属碳洋葱。结果表明,在高温时碳洋葱生成量较多,且石墨化程度高;在催化剂存在的情况下,生成碳洋葱产量高,结构缺陷较少。最后,结合本实验现象,对碳洋葱的形成机理进行了讨论。
Carbon onions were synthesized by vacuum heat treatment method, and the carbon black formed in the carbonization of iron and steel elements was chosen as the carbon source. First, the morphologies and structures of the carbon source were characterized by X-ray diffrac- tion (XRD), high resolution transmission electron microscopy (HRTEM), and the analysis of the reasons for the formation of the various component was given. Next, the vacuum heat treatment in different temperatures (1 100-1 900℃) was adopted. In the resulting products, two kinds of carbon onions were generated: carbon onions consisted of graphite layers completely and encapsulate metals nano onions. The results revealed that at higher temperatures, more carbon onions with a higher degree of graphitization could be obtained. The catalyst could play an impor- tant role in the formation of carbon onions with large quantity and well-ordered structure. There- fore, without adding catalyst, the temperature of heat treatment could be raised appropriately to produce well-ordered carbon onions. Finally, the formation mechanism of derived carbon onions was discussed.