熔融制样-X射线荧光光谱法测定钛铁合金中主量元素

目前行业内普遍存在的问题是低钛含量的钛铁合金比较容易氧化,高钛含量的钛铁合金如70钛铁在熔片过程中难氧化,铂-金坩埚腐蚀情况较严重,所用氧化剂往往很难兼顾到氧化能力和迸溅控制水平。经试验,将硝酸钾、硼酸和无水碳酸钠按1∶1∶4的质量比配制,能完全氧化高钛含量的钛铁合金,同时可有效避免迸溅损失。选择7 g四硼酸锂粉末铺底,采用2 g四硼酸锂-偏硼酸锂-氟化锂混合熔剂(m∶m∶m=65∶25∶10)覆盖样品和氧化剂,可避免铂-金坩埚被腐蚀,进而实现了X射线荧光光谱法(XRF)对钛铁合金中钛、硅、锰、铝、磷和铜等主量元素的测定。低含量锰、磷和铜的检出限依次为31.2、16.8、25.5 μg/g。精密度考察结果表明,各元素测定结果的相对标准偏差(RSD)均不大于3.0%。采用实验方法对钛铁合金标准样品和实际样品进行测试,结果与认定值或化学湿法值一致。

Determination of major elements in ferrotitanium by X-ray fluorescence spectrometry with fusion sample preparation

At present, a common problem in the industry is that ferrotitanium alloys with low titanium content are easily oxidized, but those with high titanium content such as 70 ferrotitanium are difficult to be oxidized during the melting process. In addition, the corrosion of platinum-gold crucible is relatively serious. It is difficult for the oxidants to balance both the oxidation ability and the level of splash control. According to the experiment, potassium nitrate, boric acid and anhydrous sodium carbonate were mixed in a mass ratio of 1∶1∶4, which could completely oxidize the ferro-titanium alloy with high titanium content, and meanwhile, effectively avoid splash loss. 7 g of lithium tetraborate powder was used as the bottom layer. The sample and oxidant were covered with 2 g of mixed flux composed of lithium tetraborate-lithium metaborate-lithium fluoride (m∶m∶m=65∶25∶10). This protocol could avoid the corrosion of platinum-gold crucible. In this way, the determination of major elements (including titanium, silicon, manganese, aluminum, phosphorus and copper) in ferrotitanium alloy by X-ray fluorescence spectrometry (XRF) was realized. The limits of detection for low content manganese, phosphorus and copper were 31.2, 16.8 and 25.5 μg/g, respectively. The results of precision inspection showed that the relative standard deviations (RSD) of testing elements were all not more than 3.0%. The certified reference materials and samples of ferrotitanium alloy were determined according to the experimental method, and the found results were consistent with the certified values or those obtained by the chemical wet method.