紫钨氢还原制备纳米钨 碳化钨粉体及其性能分析-preparation of nanometer tungsten tungsten carbide powder by hydrogen reduction of violet tungsten and its performance analysis.docx

华侨大学硕士论文：紫钨氢还原制备纳米钨、碳化钨粉体及其性能研究 华侨大学硕士论文：紫钨氢还原制备纳米钨、碳化钨粉体及其性能研究 IV IV boat speed，reducing the boat charging capacity and increasing hydrogen flowrate. The result showed that its shape mostly spherical, small particles and uniform distribution, but there is some unity between the particles. Its lattice shrunk, and the lattice distortion rate is inverse proportional linear relationship to the grain sizes. Nano-WC powder are prepared by carbonization rapidly in low temperature under the protection of hydrogen, using nano-W powder as raw material, carbon black as carbon. The results showed that the particle size was small and distribution uniformity and high purity; its shape mostly is spherical, plate-like and irregular, so it is very advantages to product the nano-cemented carbide. The specific surface area and pore structure of nano-W and WC powder have the best results when degassing temperature T=300℃ and degassing time t=3h. Then, the lattice of nano-W powder changed into expansion from contraction after different heated treatment temperature. With the temperature increases，the particle size increases. Its phase structure, morphology and pore structure also will be changed. We are obtained the grain growth activation energy of nano-WC powder is 4.66eV at the different heating rates. Keywords: reduction process, lattice distortion, annealing heat treatment， carbonization rapidly in low temperature，thermal stability 原创性声明 本人声明兹呈交的学位论文是本人在导师指导下完成的 研究成果。论文写作中不包含其他人已经发表或撰写过的研究 内容，如参考他人或集体的科研成果，均在论文中以明确的方 式说明。本人依法享有和承担由此论文所产生的权利和责任。 学位论文作者签名： 日期： 学位论文版权使用授权声明 本人同意授权华侨大学有权保留并向国家机关或机构送 交学位论文和磁盘，允许学位论文被查阅和借阅。 论文作者签名： 指导教师签名： 签 名 日 期： 签 名 日 期： PAGE PAGE 10 引 言 纳米材料和纳米技术是20世纪后期出现的新型材料和高新技术。当物质颗粒尺寸 减小到100nm时,由于纳米材料的小尺寸效应、表面效应、量子尺寸效应和宏观量子隧 道效应等许多独特的优异性能，呈现出许多既不同于宏观物体、也不同于单个原子的 奇异现象。如纳米晶铜在常温下具有非凡的超塑性；在钨颗粒中加0.1%～0.5%超细镍 颗粒后,可使烧结温度从3000℃降到1200～1300℃,能烧制成大功率半导体管的基片，这 是常规材料难以想像的。因此,纳米材料和纳米技术的研究得到世界各国，尤其是发达 国家的重视。在过去的二三十年里纳米材料和纳米技术的研究发展迅猛,科学家预言,21 世纪是纳米材料的世纪,它将在