碳热还原法合成硼化锆粉体影响因素探究

Effects on the Preparation of Zirconium Diboride by Carbothermal Reduction

以氧化锆(ZrO_2)、硼酸(H_3BO_3)和碳(C)粉为原料,研究了不同碳粉(活性炭、石墨)与前驱体粒度、温度及保温时间对碳热还原法制备硼化锆(ZrB_2)粉体的影响。通过X射线衍射(XRD)分析合成粉体物相,扫描电镜(SEM)观察合成粉体形貌,并通过化学方法分析了合成粉体中的C、O含量。结果表明:以活性炭为碳源合成的粉体形貌呈条棒状,以石墨为碳源合成的粉体形貌呈规则的块状;合成粉体的粒度随前驱体粒度减小而减小,形貌由规则的块状逐渐转变为圆滑的不规则形貌,合成ZrB_2粉体最小平均粒度约为1. 69μm,产物中C含量随前驱体粒度减小而减少,O含量随前驱体粒度减小而增加,氧含量最低为0. 54wt%;碳热还原法合成ZrB_2粉体在1500℃下是可行的,但直到1900℃碳热还原反应合成ZrB_2才进行完全;碳热还原反应合成ZrB_2粉体最佳的反应条件为1900℃保温30 min。

The effects of different carbon(activated carbon,graphite)powder,precursor particle size,temperature and holding time on the preparation of zirconium diboride(ZrB 2)powder by carbothermal reduction were studied using zirconium oxide(ZrO 2),boric acid(H 3BO 3)and carbon(activated carbon,graphite)powder as raw materials.The prepared powder was analyzed by X-ray diffraction(XRD),scanning electron microscopy(SEM).The content of C and O in the prepared powder was analyzed by chemical method.The results show that the powder prepared by activated carbon has a morphology of a bar while that prepared by graphite has a morphology of a regular block.The particle size of the prepared powder decreases with the decrease of the precursor particle size,with the shape gradually transformed into the smooth irregular shape.The minimum average particle size of the synthetic ZrB 2 powder was about 1.69μm.The carbon content in the product decreased with the decrease of the particle size of the precursor while the oxygen content increased with the decrease of precursor particle size and the lowest oxygen content was 0.54wt%.Synthesis of ZrB 2 powder at 1500℃is feasible by carbothermal reduction,but the reaction was not completely done until 1900℃.The best condition of carbothermal reduction for synthesis of ZrB 2 powder is 1900℃for 30 min.