硅钼蓝分光光度法测定高铍铍铝合金中硅

Determination of silicon in beryllium-aluminium alloy with high content of beryllium by silicon molybdenum blue spectrophotometry

高铍铍铝合金中的杂质元素硅对高铍铍铝合金热等静压、精密铸造及耐腐蚀性能影响较大,需要对其含量进行严格控制,所以测定高铍铍铝合金中的硅具有重要意义。采用硫酸(1+1)、硝酸和氢氟酸于水浴条件下溶解试样,用硼酸掩蔽剩余氟离子,在0.10~0.15 mol/L硫硝混酸介质下,钼酸铵与硅反应生成硅钼黄杂多酸,稳定20 min后,用草酸掩蔽铁离子,同时加入抗坏血酸将硅钼黄还原成硅钼蓝,放置10 min,于波长820 nm处采用分光光度法进行测定,实现了硅钼蓝分光光度法对高铍铍铝合金(铍的质量分数为60%~70%)中硅的测定。在优化的实验条件下,试液中硅质量在10~60μg范围内与其对应的吸光度呈良好的线性关系,相关系数为1.000,方法中硅的检出限和测定下限分别为0.002 1%(质量分数,下同)和0.007 1%。按照实验方法测定60BeAl和70BeAl两个高铍铍铝合金试样中硅含量,测得结果的相对标准偏差(RSD,n=8)为2.9%~3.4%。将实验方法用于测定高铍铍铝合金实际试样中硅含量,结果与电感耦合等离子体原子发射光谱法(ICP-AES)相吻合。

The content of impurity silicon in beryllium-aluminium alloy with high content of beryllium had great influence on its properties such as hot isostatic pressure,precision casting and corrosion resistance.Therefore,the content of silicon should be strictly controlled and it was necessary to determine the content of silicon in beryllium-aluminium alloy with high content of beryllium.The sample was dissolved by sulfuric acid(1+1),nitric acid and hydrofluoric acid in water bath.The residual fluoride ions were masked by boric acid.In the medium of 0.10-0.15 mol/L sulfur acid-nitric acid mixture,the ammonium molybdate could react with silicon to form silicon molybdenum yellow heteropolyacid.After stabilizing for 20 min,iron ions were masked with oxalic acid.Meanwhile,ascorbic acid was added to reduce silicon molybdenum yellow to silicon molybdenum blue.After placing for 10 min,the solution was determined by spectrophotometry at wavelength of 820 nm.A determination method of silicon in beryllium-aluminium alloy with high content of beryllium(the mass fraction of beryllium was 60%-70%)was established by spectrophotometry.Under the optimized experimental conditions,the mass of silicon in sample solution in range of 10-60μg had good linear relationship to its corresponding absorbance.The correlation coefficient was 1.000.The detection limit and low limit of determination for silicon was 0.002 1%and 0.007 1%(mass fraction),respectively.The contents of silicon in two beryllium-aluminium alloy samples(60BeAl and 70BeAl)with high content of beryllium were determined according to the experimental method.The relative standard deviations(RSDs,n=8)of the results were between 2.9%and 3.4%.The results were consistent with those obtained by inductively coupled plasma atomic emission spectrometry(ICP-AES).