氩-氢混合放电等离子体还原BCl_3制备高纯纳米硼粉

Preparation of boron nano-powder from BCl_3 reduced by argon-hydrogen plasma

利用氩气与氢气电弧放电产生氩-氢混合等离子体还原三氯化硼,获得还原产物纳米硼粉。在等离子体放电功率19.2 k W,氩气、氢气进气流率分别1.5 m3/h,BCl3进料量1 500 g/h实验条件下,硼粉收率达到最大值58%。利用DSCTG(热重分析仪)、XRD(X射线衍射仪)、XPS(X射线光电子能谱仪)、SEM(扫描电子显微镜)分析了样品起始氧化温度、组成、物相及形貌。结果表明,所得硼粉粒径在50~100 nm之间,其中84%为无定型硼;另外,存在六方晶胞和四方晶胞的2种晶体硼,该硼粉的起始氧化温度约在200℃。排除纳米硼粉表面的吸附氧,单质硼的纯度大于98%。通过对硼粉的洗涤和烘烤证明,用简单的去离子水洗涤可进一步提高硼粉纯度,在80℃以下,纳米硼粉在空气中几乎不被氧化。

The elemental boron nano-powder was prepared by reducing BCl_3 with argon-hydrogen thermal plasma.The maximum yield of boron powders was about 58% under the operational conditions of H2 and Ar feed flow-rate of 1.5 m^3/h,respectively,BCl_3 of 1.5 kg/h,plasma power at 19.2 k W.DSC-TG,XRD,SEM and XPS were used to test the character of the boron powder.Results show that the size of the boron powder is distributed in 50 ~ 100 nm,its initial oxidation temperature is about 200 ℃; the powder is comprised of amorphous boron of 84% and hexagonal,tetragonal crystal structures.Getting rid of the adsorbed oxygen,the purity of the elemental boron is more than 98%,it could be further improved by deionized water washing.The boron powders could hardly be oxidized even in 80 ℃ baking oven and air ambience.