混合盐辅助燃烧合成纳米ZrC粉体及影响机制  

Effect of mixed salts on combustion synthesis of nano-ZrC powder

作　　者：许珂 占发琦 张华[1] 安宁[1] 吴浩恺 朱敏[1] 郑月红 喇培清[1] XU Ke;ZHAN Faqi;ZHANG Hua;AN Ning;WU Haokai;ZHU Min;ZHENG Yuehong;LA Peiqing(State Key Laboratory of Advanced Processing and Recyclingof Nonferrous Metals,Lanzhou University of Technology,Lanzhou 730050,China)

机构地区：[1]兰州理工大学省部共建有色金属先进加工与再利用国家重点实验室,兰州730050

出　　处：《功能材料》2021年第10期10177-10186,10220,共11页Journal of Functional Materials

基　　金：国家自然科学基金资助项目(51911530119)。

摘　　要：采用新型的盐助燃烧合成工艺,在ZrO_(2)-Mg-C体系中,加入NaCl-KCl混合盐作为稀释剂,宏量制备出纯相的纳米级ZrC粉体,中位径D 50=46 nm。通过计算该体系下的自由能和绝热温度,结合热力学和动力学分析,探究NaCl-KCl的加入量对ZrC粉体的纯度和粒度的影响规律及其作用机制。结果表明,当稀释剂含量w在0~30%(质量分数,下同)范围内,稀释剂NaCl-KCl的加入有利于获得纯相的ZrC,但在颗粒表面会吸附少量的游离碳,产物ZrC的纯度在90%以上。当NaCl-KCl的加入量为30%时,ZrC的纯度为97.26%。另外,随着NaCl-KCl含量的增加,ZrC颗粒的平均粒径从476 nm降至46 nm。其中较小的颗粒尺寸更容易被氧化,在颗粒表面形成2.9 nm的Zr(C_(x)O_(y))壳层。NaCl-KCl的作用机理主要是相变吸热和加速形核,通过相变吸热降低绝热温度和体系的冷却速率,增加过冷度,从而增加了晶体的形核速率。另外,熔融盐提供液相环境加速物质传输,有利于生成纯相ZrC。Using a new salt-assisted combustion synthesis technology with adding NaCl-KCl mixed salt as diluent in the ZrO_(2)-Mg-C system,the pure phase nano ZrC powder with median diameter(D50)of 46 nm is prepared on a large scale.By calculating the free energy and adiabatic temperature of the system,combined with thermodynamic and kinetic analysis,the influence of the amount of NaCl-KCl on the purity and particle size of ZrC powder and its formation mechanism were investigated.The results show that when the content of diluent w is in the range of 0-30 wt%,the addition of diluent NaCl-KCl is beneficial to obtain pure phase ZrC,but a small amount of free carbon will be adsorbed on the particle surface,and the purity of ZrC is over 90 wt%.When the addition of NaCl-KCl is 30 wt%,the purity of ZrC is 97.26 wt%.In addition,with the increase of NaCl-KCl content,the average particle size of ZrC particles decreases from 476 nm to 46 nm.The smaller particle size is more easily oxidized,forming 2.9 nm Zr(C_(x)O_(y))shell layer on the particle surface.The mechanism of action of NaCl-KCl is mainly phase change endothermic and accelerated nucleation.The adiabatic temperature and cooling rate of the system are reduced through phase change endothermic,and the degree of supercooling is increased,thus increasing the nucleation rate of the crystal.In addition,the liquid phase is provided to accelerate the material transfer,which is conducive to the formation of pure phase ZrC.

关 键 词：盐助燃烧合成 NaCl-KCl稀释剂 纳米ZrC粉体 作用机制 

分 类 号：TQ134[化学工程—无机化工]