控制气氛-直流电弧放电中氟化反应研究高效氟化剂CuOHF和CuF_2·2H_2O

Study on Fluoration in DC Arc Discharge in Ar-O_2 Atmosphere——Highly Effective Fluoration Reagents CuOHF and CuF_2·2H_2O

本文研究了NaF、CaF_2、CuOHF、CuF_2·2H_2O和聚四氟乙烯(PTFE)五种氟化剂对碳粉中微量元素La、Zn、Ni、Cr、Mn蒸发行为的影响,以CuOHF和CuF_2·2H_2O氟化效果最好。用实验方法制作了上述元素的积分强度-时间曲线,并计算出元素完全蒸发的半衰期,以此定量评价氟化反应对元素蒸发行为的影响。考察了不同氟化剂对元素谱线的增强因子,以对La和Cr的谱线增强最为显著。应用CuOHF、CuF_2·2H_2O氟化剂测定La,不仅可提高元素La的蒸发速率(缩短曝光时间2倍),而且可极大提高La的谱线强度,增强因子分别为28.8(对CuF_2·2H_2O)和23(对CuOHF)。还对氟化剂的用量进行了实验选择。考虑到燃弧的稳定性,背景发射以及灵敏度诸因素,以含5％氟化剂为宜。

The influence of the fluoration reagents (NaF, CaF_2, CuOHF, CuF_2·2H_2O and polytetrafluoroe thylene) on the evaporation behavior of microamounts of elements La, Zn, Ni, Cr and Mn in carbon powder was investigated. The evaporation ratio of the element in electrode cavity can be quantitatively calculated by use of its evaporation half-life obtained from the integrated value of the intensity versus exposure time curve It is experimentally found that CuOHF and CuF_2·2H_2O are the most effective in rapid evaporation of elements in all studied fluoration reagents. The spectral line intensities of the elements increase very significantly, when using CuF_2·2H_2O as the fluoration reagent, for example, by a factor of 28.8 for La and by a factor of 5.7 for Cr. Therefore fluoration reagent such as CuOHF or CuF_2·2H_2O not only increases the element evaporation ratio, but also enhances greatly the line intensity. A compromise 5% CuOHF or CuF_2·2H_2O concentration was chosen to determine microamounts of impurities in carbon powder.