（毕业设计论文）《制备纳米碳化钒设计》.doc

PAGE 摘 要 本文以偏钒酸铵和纳米碳黑为原料，先将原料制成前驱体粉末，再在真空碳管炉中进行碳热还原反应，在一定条件下制备纳米碳化钒粉体。偏钒酸铵在150℃左右分解为五氧化二钒、氨气和水，使碳和钒氧化物得到充分混合，因而扩散距离缩短，碳化温度降低，反应时间缩短，晶粒尺寸得到有效控制。主要采用了XRD、SEM等分析手段研究了不同工艺条件（反应温度、保温时间、配碳量）对制备纳米碳化钒的影响，通过研究得到以下主要结论。 以纳米碳黑和偏钒酸铵为原料可在1100℃时制备相成分单一的V8C7粉体，粉末颗粒的形貌较规则，粉末粒度较小，呈球形或类球形，粉末颗粒的平均粒度小于100nm。当保温时间达到或接近最佳值（本实验为60min）时，反应才能进行彻底，颗粒的形貌较规则，且形貌细小。当碳含量为28%时，主相为V8C7，不含其它杂质相，并且晶格常数最接近理论值。 关键词：碳化钒 碳热还原法 偏钒酸铵 Title Study on Preparation of Nanometer VC Powder Abstract This paper deals with a new method to prepare nanometer vanadium carbide powder under certain conditions. The raw materials including NH4VO3 and nanometer carbon were made into the precursor powder first. The carbothermal reduction happened in the vacuum carbon tube furnace.NH4VO3 is decomposed into V2O5 NH3 and H2O about 150 ℃, so the carbon and vanadium oxides are fully mixed, and thus reduce the diffusion distance, carbonization temperature decreases, shorter reaction time the grain size has been effectively controlled.The effects of process conditions (reaction temperature, keeping time and proportioning ratio of the carbon powder) were investigated by X-ray diffraction and scanning electron microscope (SEM). The results are listed as follows: Using NH4VO3 as raw materials, V8C7 powder of single phase can be obtained at 1100℃. The morphology of the powder is rather order and spheroid or similar to spheroid. The particle size is less than 100nm. When the holding time at or close to the optimum value (in this experiment 60min), the reaction can be carried out thoroughly, more regular particle shape, and morphology of small. When the carbon content was 28%, the main phase V8C7, without other impurity phase, and the lattice constant of the closest theoretical value. Keywords: Vanadium Carbide Carbothermal Reduction NH4VO3 目 次 TOC \o 1-3 \h \z \u HYPERLINK \l _Toc262918721 1 绪论 PAGEREF _Toc262918721 \h 1 HYPERLINK \l _Toc262918722 1.1碳化钒的性质及用途 PAGEREF _Toc262918722 \h 1 HYPERLINK \l _Toc262918723 1.1