熔融制样-X射线荧光光谱法测定硅铁中硅磷锰铝钙铬

熔融制样-X射线荧光光谱法(XRF)测定硅铁合金样品,需重点解决样品前处理中合金样品侵蚀铂-黄坩埚的难题。硅铁样品以四硼酸锂-碳酸锂预氧化剂在石墨垫底瓷坩埚中高温预氧化熔融后,再将熔融物转移至铂-黄坩埚中,用四硼酸锂熔融制成玻璃熔片,实现了熔融制样-X射线荧光光谱法对硅铁合金中硅、磷、锰、铝、钙、铬的测定。实验讨论了预氧化熔融的熔剂体系及氧化方法、试样与熔剂的稀释比,结果表明,试样与熔剂以1∶35的稀释比,以10滴300g/L碘化钾溶液为脱模剂,在1100℃熔融30min,熔融制得的玻璃片均匀、透明、无气泡,符合测定要求。用具有浓度梯度的系列硅铁有证标准样品制作校准曲线,各待测元素校准曲线的线性相关系数均大于0.9995。方法应用于硅铁合金实际样品中硅、磷、锰、铝、钙、铬的测定, 结果的相对标准偏差(RSD,n=11)在0.1%~5.8%之间;正确度试验表明,硅铁标准样品的测定结果与认定值相符,硅铁实际样品的测定结果与国家标准方法测定值一致,能满足常规分析要求。

Determination of silicon,phosphorus, manganese,aluminum, calcium and chromium in ferrosilicon by X-ray fluorescence spectrometry with fusion sample preparation

During the determination of ferrosilicon sample by X-ray fluorescence spectrometry (XRF) with fusion sample preparation, the corrosion of platinum-gold crucible by alloy sample in sample pretreatment should be solved. Ferrosilicon sample was pre-oxidized and fused at high temperature in porcelain crucible with graphite on the bottom using lithium tetraborate-lithium carbonate as the pre-oxidation reagent. Then the melt was transferred into platinum-gold crucible for sample preparation using lithium tetraborate as flux. The determination of silicon, phosphorus, manganese, aluminum, calcium and chromium in ferrosilicon by XRF with fusion sample preparation was realized. The flux system and oxidation method in pre-oxidation fusion as well as the dilution ratio between sample and flux were investigated in experiments. The results showed that the prepared sample was uniform and transparent without bubbles, which could meet the determination requirements, under the following conditions: the dilution ratio between sample and flux was 1∶35; the release agent was 10 drops of 300g/L potassium iodide solution; the sample was fused at 1100℃ for 30min. The certified reference materials of ferrosilicon with series of concentration gradient were employed to prepare the calibration curves. The linear correlation coefficients of calibration curves for testing elements were all higher than 0.9995. The proposed method was applied for the determination of silicon, phosphorus, manganese, aluminum, calcium and chromium in actual sample of ferrosilicon. The relative standard deviations (RSD, n=11) of determination results were between 0.1% and 5.8%. The accuracy test showed that the determination results of ferrosilicon standard sample were consistent with the certified values. The determination results of actual ferrosilicon samples were consistent with those obtained by national standard methods. The proposed method could meet the requirements of routine analysis.