粉末压片-能量色散X射线荧光光谱法分析硅铬合金中铬硅磷

采用能量色散X射线荧光光谱仪替代传统化学湿法分析测定硅铬合金中铬、硅、磷的含量,可实现在减少人力物力、绿色环保的前提下满足生产的需要。实验采用粉末压片法,通过试验确定将40g破碎缩分样品研磨20s制成120目(124μm)化学分析样,然后在25.00g化学分析样中加入0.20g硬脂酸和2.00g微晶纤维素,研磨90s使其粒度不小于200目(74μm以下),在此条件下研磨压制成片后分析面坚固平滑。根据铬、硅、磷3元素的特点,确定光谱仪最佳工作参数,选择低功率一次靶在不加滤光片抽真空的条件下测定硅和磷,用大功率的二次靶模式测定铬。由于硅铬合金标准样品较少,因此实验选取硅铬合金不同生产阶段且含量呈梯度的多个经化学湿法准确定值的样品作为校准样品建立校准曲线。采用经验系数法校正元素间的影响,消除基体效应、粒度效应,降低谱线重叠干扰。精密度试验表明,硅铬合金样品中铬、硅、磷测定结果的相对标准偏差(RSD,n=10)依次为0.002%、0.002%和0.016%;对硅铬合金生产样品进行正确度考察,测定值与化学湿法分析值一致。方法实现了X射线荧光光谱仪对硅铬合金中铬、硅、磷等元素的同时测定,开拓了仪器应用的新领域。

Determination of chromium,silicon and phosphorus insilicochrome by energy dispersive X-ray fluorescencespectrometry with pressed powder pellet

As the determination of chromium, silicon and phosphorus in silicon-chromium alloy by traditional chemical wet analysis method was replaced by energy dispersive X-ray fluorescence spectrometry, the requirements of production could be met from the premise of reducing manpower and material resources as well as green environmental protection. The pressed powder pellet was selected for sample preparation. 40g of crushed sample was ground for 20s to prepare 120-mesh (124μm) sample for chemical analysis. Then 0.20g of stearic acid and 2.00g of microcrystalline cellulose were added into 25.00g of sample for chemical analysis. The mixture was ground for 90s to reduce the particle size not less than 200-mesh (74μm). The analysis surface of the prepared sample pellet was smooth and firm under the conditions above. According to the characteristics of chromium, silicon and phosphorus, the optimal working parameters of spectrometer were obtained. The contents of silicon and phosphorus were determined under vacuum condition using low power primary target without optical filter, while the content of chromium was determined using high power secondary target mode. Due to the lack of certified reference materials for silicochrome alloy, several silicochrome alloy in different production stages with certain content gradient (the contents were accurately determined by chemical wet method) were used as calibration samples to establish the calibration curve. The influence among elements, the matrix effect, the particle size effect and the spectral overlapping interference was corrected or reduced by the empirical coefficient method. The precision test indicated that the relative standard deviation (RSD, n=10) was 0.002%, 0.002% and 0.016% for chromium, silicon and phosphorus in silicochrome alloy, respectively. The trueness test for production sample of silicochrome alloy was also conducted. The results were consistent with those obtained by chemical wet method. The proposed method realized the simultaneous determination of chromium, silicon and phosphorus in silicochrome alloy by X-ray fluorescence spectrometer, which broadened the new application fields of instrument.