碳热还原氮化法制备UN粉末机理研究  

Study on the Mechanism of Preparing UN Powders by Carbothermal Reduction and Nitridation Method

作　　者：吴学志[1] 郭骁 李石泉 何晓军[1] 贺新福[1] WU Xuezhi;GUO Xiao;LI Shiquan;HE Xiaojun;HE Xinfu(China Institute of Atomic Energy,Beijing 102413,China)

机构地区：[1]中国原子能科学研究院,北京102413

出　　处：《材料导报》2024年第S02期1-4,共4页Materials Reports

摘　　要：氮化铀(Uranium nitride)燃料具有金属铀密度高、热导率高、热膨胀系数低及与液态金属相容性好等优点,是未来先进反应堆设计选用燃料之一。高相纯度、高活性UN粉末是制备高密度UN芯块的前提。采用碳热还原氮化法制备UN粉末,研究了工艺参数对UN粉末反应动力学、相结构、晶格常数及氮铀比的作用机制和影响规律。结果表明:UN粉末相结构与原料C/UO_(2)物质的量比及合成温度有关,当原料C/UO_(2)物质的量比为2.7、合成气氛为N_(2)-5%H_(2)(0.1~0.15 MPa)、合成温度为1700℃时,可制备得到高相纯度UN粉末;中间反应产物U_(2)N_(3)在1200℃以下、真空环境、大于2 h可分解为UN粉末;UN晶格常数与粉末中相成分有关,当N/U比接近1时,其晶格常数为0.48882 nm;合成的UN粉末经转速600 r/min、球磨时间4 h、球料比5∶1的工艺参数球磨,可制备得到粒度为0.96μm的UN细粉末。Uranium nitride fuel has the advantages of high density of metallic uranium,high thermal conductivity,low coefficient of thermal expansion,and good compatibility with liquid metals,making it one of the preferred fuels for future advanced reactor designs.High phase purity and high activity UN powders are prerequisites for preparing high-density UN pellets.The paper adopts the carbon thermal reduction nitriding method to prepare UN powders,and studies the mechanism and influence of process parameters on the reaction kinetics,phase structure,lattice constant,and nitrogen uranium ratio of UN powders.The results showed that the phase structure of UN powders was related to the molar ratio of raw materials C/UO_(2)and the synthesis temperature.High phase purity UN powders could be prepared when the molar ratio of raw material C/UO_(2)was 2.7,the synthesis atmosphere was N_(2)-5%H_(2)(0.1-0.15 MPa),and the synthesis temperature was 1700℃.The intermediate reaction product U_(2)N_(3)could decompose into UN at a temperature below 1200℃in a vacuum environment for more than 2 h.The lattice constant of UN was related to the phase composition in the powders,and it was 0.48882 nm when the N/U ratio was close to 1.UN fine powders with a particle size of 0.96μm could be prepared by ball milling the synthesized UN powder under the process parameters of a rotational speed of 600 revolutions per minute,a ball milling time of 4 h,and a ball-to-powder ratio of 5∶1.

关 键 词：碳热还原 氮化铀 燃料 氮铀比 晶格常数 

分 类 号：TL352.21[核科学技术—核技术及应用]