熔融制样-X射线荧光光谱法测定锰铁合金中硅锰磷

采用传统化学湿法测定锰铁合金中化学组分需要使用强酸、强碱等化学试剂,耗时长且操作技能不易掌握。为拓展X射线荧光光谱仪(XRF)测定锰铁合金的应用,实验在垫有石墨粉的陶瓷坩埚内,用滤纸包裹定量的样品和锰铁合金氧化剂,于800 ℃马弗炉内进行氧化,氧化后的样品转移至铂-黄坩埚内,以四硼酸锂为熔剂,用高频熔样机制备XRF用玻璃熔片,实现铂-黄坩埚外氧化试样,克服高频熔样机配套铂-黄坩埚容积小、挂壁制备熔剂坩埚等困难,有效解决了锰铁合金样品熔融过程中单质元素与铂形成低温共熔体而损坏铂-黄坩埚的难题。经条件试验,优化后的熔融条件为称样量0.200 0 g,助熔剂用量为5.000 0 g,熔样温度1 050 ℃,熔样时间12 min,进而实现了熔融制样-X射线荧光光谱法对锰铁合金中硅、锰、磷含量的测定。硅、锰、磷校准曲线决定系数不小于0.999 8。实验方法应用于锰铁合金日常检测,硅、锰、磷测定结果的相对标准偏差(RSD, n=10)均小于3%;标准样品的测定值与认定值间误差均可控制在国标化学分析方法允许差范围内。

Determination of silicon,manganese and phosphorus in ferromanganese alloy by X-ray fluorescence spectrometry with fusion sample preparation

Chemical reagents such as strong acid and alkali are required during determination of chemical composition in ferromanganese alloy by traditional chemical wet method, which is time-consuming. Moreover, the operation skill is difficult to master. The application of X-ray fluorescence spectrometry (XRF) in the determination of ferromanganese alloy was investigated. A certain amount of sample and ferromanganese alloy oxidant were wrapped with filter paper in a ceramic crucible containing graphite powder. The sample was oxidized in a muffle furnace at 800 ℃. The oxidized samples were transferred to a platinum yellow crucible to prepare glass sheets for XRF analysis by a high-frequency melting machine with lithium tetraborate as the flux. As a result, the oxidization of samples outside the platinum-gold crucible was realized. It was effective to overcome the difficulties such as small volume of the platinum-gold crucible matched with the high-frequency melting machine and the preparation of flux crucible on the wall. Moreover, this method effectively solved the problem that the elements in ferromanganese alloy sample formed low temperature eutectic with platinum in fusion process, which would damage the platinum-gold crucible. Through conditional experiments, the fusion conditions were optimized as below: the sample mass was 0.200 0 g; the flux mass was 5.000 0 g; the sample fusion temperature was 1 050 ℃; the fusion time was 12 min. Consequently, a method for determination of silicon, manganese, and phosphorus in ferromanganese alloy was established by XRF with fusion sample preparation. The determination coefficients of calibration curves for silicon, manganese, and phosphorus were all not less than 0.999 8. The experimental method was applied to the daily inspection of ferromanganese alloy. The relative standard deviations (RSD, n=10) of determination results were all lower than 3%. The errors between the measurement values and certified values of certified reference materials could be controlled within the permissible range of chemical analysis method in national standard.