熔融制样-X射线荧光光谱法测定Ti(C,N)基金属陶瓷中钛钨钴铌镍钼

Determination of titanium,tungsten,cobalt,niobium,nickel,molybdenum in Ti(C,N) based cermets by X-ray fluorescence spectrometry with fusion sample preparation

目前针对Ti(C,N)基金属陶瓷进行X射线荧光光谱(XRF)测试的相关报道甚少。实验通过酸溶解前处理、低温烘干后熔融制样,人工配制氧化物标样建立X射线荧光光谱分析校准曲线,并尝试内标法,实现快速测定金属陶瓷中Ti、W、Co、Nb、Ni、Mo元素。比较了预氧化与酸溶解两种样品前处理方式,发现经酸溶、烘干再熔片即可避免高温熔融时W、Mo的损失。选择7.72g混合熔剂[m(Li_2B_4O_7)∶m(LiBO_2)=67∶33],0.7g助氧化剂NH_4NO_3,8滴150g/L脱模剂LiBr溶液,熔融温度1 100℃,熔融时间190s的熔样条件可制得均一熔片。采用两组称样量0.12~0.25g、0.08~0.23g,通过大幅变更样量来放大基体效应,观测参数变动的影响,以最少实验量确定最优组合。采用Ta内标法,无需对结果进行归一化处理,可显著提高方法的精密度;元素Co、Ni适用Ta-Lα线校正;W、Nb适用Ta-Lβ1线校正。分别用内标法与非内标法制备样品以进行精密度考察,结果表明,对于内标法,测定结果的相对标准偏差RSD<1.0%;对于非内标法,RSD<2.5%。用不同配方的Ti(C,N)基金属陶瓷试样进行正确度验证,测定值与参考值一致。

There are rare reports about the determinat ion of Ti （C, N） in cermets by X-ray fluorescence spectrometry（XRF）. Ti （C, N） based cermets sample was pretreated through acid dissolution and low temperature drying, and then prepared by fusion sample preparation method. Artificially-prepared oxide standard sample was used for establishing calibration curve of X-ray fluorescence spectrometric analysis, so that rapid qualitative determination for Ti, W, Co, Nb, Ni, Mo of cermets was achieved with internal standard method. Two pretreatment methods of preoxidation and acid dissolution were compared in the experiment, which found that the mass-loss of W and Mo during high temperature fusion could be avoided by acid dissolving, drying,and smelting . With 7. 72 g of mixed flux [ m（Li2 B4O7 ） ： /n（LiBO2 ） = 6 7 ： 3 3] , 0.7 g of auxiliary oxidant NH4N03 , 8 drops of 150 g/L release agent LiBr solution, uniform fuse piece could be produced at the fusion temperature of 1 100℃ and the fusion time of 190 s. Two groups of samples （0. 12-0. 25 g , 0. 08-0. 23 g） were weighed for contrast test. Through varying sample mass to enlarge matrix effect, the influence of the parameters on the test results could be directly observed, so that the optimum parameters could be selected with the least experiment times. Using Ta as internal standard, the precision could be improved significantly without normalizing the results. For Co and Ni, Ta-Lα spectral line was better for correction; for W and Nb, Ta-Lα spectral line was better. Results precision was tested with samples prepared by internal and non-internal standard methods. The results showed that the relative standard deviation of internal standard method was RSD〈C1. 0 % , while that of non-internal standard method was RSD〈C2. 5 Ti （C,N）-based cermets samples of different formula were used for testing trueness,and the measured values are consistent with the reference values.