摘要
用NaBH4还原CoCl2水溶液中的Co2+离子成功制备出Co-B二元超细粉末.用化学分析法分析了反应产物中的硼的质量分数;用X射线衍射及选区电子衍射研究了所制备粉末的结构;用扫描电镜及透射电镜观察了粉末的形貌和粒径;用差示扫描量热法研究了成分为Co74.4B25.6的非晶粉末的非等温晶化动力学.实验结果表明,NaBH4溶液往CoCl2水溶液中的加入速度对粉末中的硼含量有较大影响,当加入速度由0.58 ml/min提高到1.17ml/min时,产物中硼的原子数分数由22.2%增加到28.6%.所制备的粉末由粒径小于100 nm团聚颗粒组成.在实验选定的三种分散剂中,酒石酸钠的分散效果相对较好.所制备的不同成分的粉末都具有非晶结构,并且Co74.4B25.6非晶粉末的晶化通过一个放热反应完成.差示扫描量热曲线上没有显示玻璃化转变,也不存在过冷液相区.X射线衍射结果显示晶化析出相为Co、Co2B及Co3B.采用Kissinger峰移法计算出该合金表观晶化激活能为(422.76±4.89)kJ/mol.
Ultrafine amorphous Co-B alloy powders have been prepared by means of reduction of the ion Co2^＋ in hydrolytic solution of CoClz with NaBH4. The mass fraction of boron in the as-prepared sample was analyzed by chemical analysis, the arnorphicity of the prepared powder was investigated by XRD and SAED, The morphology and the particle size were observed by TEM and SEM, and the non-isothermal crystallization kinetics of the alloy with composition of Co74.4 B25. 6 was investigated by DSC. The results showed that the adding rate of NaBH4 solution into hydrolytic solution of CoCl2 affected significantly the boron content in the obtained powders. The atomicity fraction of boron element increased from 22.2% to 28. 6% when the adding rate increased from 0. 58 ml/min to 1.17ml/min. The as-prepared sample had an aggregative morphology which was composed of many interconnected fine particles with sizes less than 100 nm. The sodium tartrate exhibited a relatively better dispersant effect among the three selected dispersers. It is found that all the DSC traces had a single exothermic peak and exhibited no glass transition and supercooled liquid region before the onset of crystallization. It was confirmed by X-ray diffraction that the structure after crystallization consisted of Co, Co2B and Co3B phases. The crystallization activation energy was determined as （422. 76±4. 89） kJ/mol by the Kissinger＇s peak-shifting method.
出处
《兰州理工大学学报》
CAS
北大核心
2006年第4期5-9,共5页
Journal of Lanzhou University of Technology
基金
国家863计划(2003AA32X50)
关键词
钴硼合金
超细非晶合金粉末
化学还原
晶化动力学
Co-B alloy
ultrafine amorphous alloy powder
chemical reduction
crystallization kinetics
作者简介
徐惠（1965-），女，甘肃武威人，博士．
