熔融制样-X射线荧光光谱法测定中低碳锰铁合金中锰硅磷铁

采用熔融制样-X射线荧光光谱法(XRF)测定锰铁合金中主次组分,需重点解决样品前处理中锰铁合金浸蚀铂-金坩埚的难题。实验以四硼酸锂为熔剂、碳酸锂为氧化剂,采用分步升温氧化中低碳锰铁合金,成功制备了中低碳锰铁合金玻璃片,建立了X射线荧光光谱法测定中低碳锰铁合金中锰、硅、磷、铁的方法。试验确定了最佳制样条件:以8.0000g四硼酸锂熔融挂壁作为坩埚保护层,称取0.4000g中低碳锰铁合金、0.8000g碳酸锂,混匀;将坩埚移入熔融炉,在650℃下保持20min,700℃下保持20min,720℃保持20min,升温至750℃保持40min,升温至820℃保持40min,升温至1100℃;取出冷却,加入约0.6g碘化铵,再移入炉内摇摆熔融30min,制得均一的玻璃片。实验方法用于测定1个中低碳锰铁合金实际样品中锰、硅、磷、铁,结果的相对标准偏差(RSD,n=11)为0.24%~1.0%;按照实验方法测定2个标准样品和3个中低碳锰铁合金实际样品,测定值与标准值或者化学湿法值相一致。实验方法有效解决了中低碳锰铁合金熔融制样过程中腐蚀铂-金坩埚的难题,对中低碳锰铁合金非常关注的磷元素,检出限为0.0030%(质量分数,下同),测量限为0.0090%,能够满足中低碳锰铁原料的检测要求,并且实现了主次成分的快速定量分析。

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

During the determination of major and minor components in ferromanganese alloy by X-ray fluorescence spectrometry (XRF) with fusion sample preparation, the etching of platinum-gold crucible by ferromanganese alloy in sample pretreatment is a difficulty which must be focused on and solved. The medium-low carbon ferromanganese alloy sample was oxidized stepwise at high temperature using lithium tetraborate as flux and lithium carbonate as oxidizer. The glass tablet of medium-low carbon ferromanganese alloy was successfully prepared. The determination method of manganese, silicon, phosphorus and iron in medium-low carbon ferromanganese alloy by XRF was established. The optimal sample preparation conditions were obtained in experiments: 8.0000g of lithium tetraborate was fused and built-up on wall of platinum-gold crucible for protection layer; 0.4000g of medium-low carbon ferromanganese alloy and 0.8000g of lithium carbonate were mixed; the crucible was transferred into melting furnace and kept at 650℃ for 20min, then at 700℃ for 20min, at 720℃ for 20min, at 750℃ for 40min, at 820℃ for 40min and finally at 1100℃. After taking out and cooling, about 0.6g of ammonium iodide was added. The crucible was then transferred into furnace; the sample was fused for 30min by swing to prepare uniform glass tablet. The experimental method was applied for the determination of manganese, silicon, phosphorus and iron in one actual sample of medium-low carbon ferromanganese alloy. The relative standard deviations (RSD, n=11) of determination results were between 0.24% and 1.0%. Two standard samples and three actual samples of medium-low carbon ferromanganese alloy were determined according to the experimental method, and the found results were consistent with the standard values or those obtained by wet chemical method. The proposed method could effectively solve the corrosion problem of platinum-gold crucible in fusion sample preparation of medium-low carbon ferromanganese alloy. The detection limit of phosphorus which was very concerned in medium-low carbon ferromanganese alloy was 0.0030% (mass fraction, similarly hereinafter), and the low limit of determination was 0.0090%. It could meet the testing requirements of medium-low carbon ferromanganese alloy. Moreover, the rapid and quantitative analysis of major and minor components was realized.