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以氧氯化锆、氨水、乙醇为原料,通过化学沉淀法获得含氢氧化锆沉淀的悬浊液,向悬浊液中加入可溶性蔗糖作为碳源,均匀混合后将悬浊液烘干得到前驱体粉体。将前驱体粉体压成圆柱形坯体,在流动的氩气气氛保护下进行高温固相反应来合成Zr C粉体。通过热力学计算分析了碳热反应合成Zr C的反应机制及适宜的温度和CO分压条件。计算结果表明反应式Zr O2+3C=Zr C+2CO(g)的标准生成吉布斯自由能在1900 K以上为负值;而随着CO分压的降低,反应的标准生成吉布斯自由能随之降低。通过X射线衍射(XRD)分析研究了前驱体的Zr/C摩尔比、反应温度、反应时间以及氧分压对高温反应产物物相的影响,优化了Zr C的合成条件。进一步的热力学分析表明,氧分压足够低时Zr C才能稳定存在。最终采用蔗糖作为碳源,Zr/C摩尔比设为1∶3,将前驱体包埋在活性炭中并在流动的高纯氩气保护下经1600℃反应240 min后得到的立方相Zr C粉体,粉体颗粒近球形,小于100 nm。
Taking zirconium oxychloride, ammonia water and ethanol as raw materials, obtaining a suspension containing zirconium hydroxide precipitate by chemical precipitation, adding soluble sucrose as a carbon source to the suspension, uniformly mixing and drying the suspension to obtain a precursor Body powder. The precursor powder is pressed into a cylindrical body, and ZrC powder is synthesized by carrying out high-temperature solid-phase reaction under the protection of a flowing argon atmosphere. The thermodynamic calculation was used to analyze the reaction mechanism and the suitable temperature and CO partial pressure conditions for the synthesis of ZrC by carbothermal reaction. The calculation results show that the Gibbs free energy of the standard formation of the reaction formula Zr O2 + 3C = Zr C + 2CO (g) is negative at more than 1900 K. With the decrease of CO partial pressure, the standard of reaction generates Gibbs freedom Can be reduced. The effects of Zr / C molar ratio, reaction temperature, reaction time and oxygen partial pressure on the phase of high temperature reaction products were investigated by X-ray diffraction (XRD). The synthesis conditions of ZrC were optimized. Further thermodynamic analysis shows that Zr C is stable at low enough oxygen partial pressure. Finally, sucrose was used as carbon source and Zr / C molar ratio was set as 1: 3. The precursor was embedded in activated carbon and the cubic ZrC powder obtained after reaction at 1600 ℃ for 240 min under flowing high purity argon gas Body, powder particles nearly spherical, less than 100 nm.