材料期刊网

以攀枝花钛精粉为载体,使用大载荷热重分析仪,在H2和CO混合气中,研究了纳米碳管的制备工艺.利用热重分析（TG）、气相色谱分析（GC）、扫描电镜（SEM）、比表面积（BET）、透射电镜（TEM）和X射线衍射（XRD）对工艺过程中产物相组成及其微观形貌进行了表征.结果表明：攀枝花钛精粉在H2-CO气氛中,由于气基还原和析碳作用,其热重曲线首先随时间的延长而逐渐降低,达最低点后逐渐升高;生成纳米碳管的最佳工艺参数是钛精粉首先经过还原制备还原产物,其相主要由Fe和M3O5固溶体组成;随后在体积浓度80%的一氧化碳气氛中逐渐降温,温度达550℃时恒温2 h;制备的纳米碳管量约是原矿粉质量的3.5倍,直径小于100 nm、比表面积约151 m2/g;纳米碳管的产生是以铁为析碳基体,且还原产物中其他矿相有效阻止了铁颗粒的团聚,其生长是吸附-反应-产物扩散的过程.

A preparation technology of carbon nanotubes was studied in hydrogen and carbon monoxide by heavy loading thermogravimetric analysis,using Panzhihua ilmenite concentrate as catalysts.During the process,the phase composition and microstructures of the products were characterized by means of thermogravimetry,gas chromatographic analysis,scanning electron microscopy,specific surface area,transmission electron microscope and X-ray diffraction.The results indicated that the weight of ilmenite concentrate decreased firstly and then increased gradually with reaction time under H2-CO atmosphere owing to gas-basis reduction and deposition of carbon.The optimal process was that the reductive products with Fe and M3O5 solid solution phase were prepared by reduction of titanium concentrate,and the temperature was decreased in 80%carbon monoxide gradually and kept 550 ℃ for 2 h.The carbon nanotubes,which were less 100 nm of diameter and 151 m2/g of specific surface,were about 3.5 times than the ilmenite concentrate.The iron was regarded as matrix material of producing of carbon nanotubes and its agglomeration was prevented by other mineral phase owing to mutual infiltration.Growth of carbon nanotubes were controlled by adsorption,reaction and diffusion during the process.