以碳纳米管为模板在熔盐介质中制备碳化钽

摘要

以不同结构的碳纳米管为反应模板,在KCl-LiCl混合盐体系中,利用熔盐反应成功制备了碳化钽纳米纤维和碳化钽涂层,并对反应产物和相应的碳管模板分别进行了SEM、TEM、XRD和SAED表征.结果表明,碳管的晶体结构对碳化钽涂层的形成具有显著地影响,经高温处理后碳管的晶体结构趋于完整,但反应性变差.通过控制金属钽和碳管的摩尔比可以选择性地得到碳化钽纳米纤维和碳化钽涂层,且产物的形貌与它们的碳管前驱体类似.同时,反应时间和反应温度对碳化钽的形成有较大影响.%Tantalum carbide (TaC) nanofibers and coatings were synthesized using multiwall carbon nanotubes (MWCNTs) with different structures as templates and the carbon source in a KCl-LiCl molten salt mixture (41.2/58.8 mol/mol).The TaC and MWCNTs were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction and selected area electron diffraction.Results indicate that the microstructure of the MWCNTs has a distinct influence on the formation of a TaC coating on the MWCNTs.MWCNTs heat-treated at 2 900 ℃ have a higher crystallinity and are harder to react with Ta to form TaC than those without the heat-treatment.The formation of TaC nanofibers or TaC coatings on MWCNTs is dependent on the molar ratio of tantalum to carbon nanotubes.The morphology of the polycrystalline cubic TaC nanofibers and the TaC coating is similar to that of MWCNTs.The reaction time and temperature have a great influence on the conversion of carbon to TaC and its crystallite size.