可视滴定法测定高温合金中镍的不确定度评定

Evaluation of Uncertainty in Measurement of Nickel in Superalloys by Method of Visual Titration

采用丁二酮肟-EDTA可视滴定法测定高温合金中的镍含量,应用统计学理论对其分析结果不确定度的产生原因进行分析,建立测量过程的数学模型,分析测量过程不确定度来源及各不确定度分量对总不确定度的影响,确定测定结果的置信区间。此方法测量不确定度的最主要来源为称量引入的不确定度和肉眼判断滴定终点引入的相对标准不确定度。所以在实际的分析过程中,可根据实际情况,采取相应措施,规范操作,提高检测分析人员的技术水平,从而保证测量结果的准确可靠。当测试样品中镍含量为53.34%时,其扩展不确定度为0.14%(扩展因子k=2)。

The concentration of nickel in superalloys was determined by dimethylglyoxime and EDTA visual titration. The causes of the uncertainty in measurement was discussed by statistics,mathematical model for evaluation of uncertainty in measurement was constructed and the sources of uncertainty and their effects on the total uncertainty were analyzed. The confidential interval of the results was determined.The main sources of the total uncertainty comes from the sample weighting and the titration end-point judged by naked eye.So In the process of practical analysis,according to actual condition,it should based on the practical situation,taking corresponding measures,normalizing operation and improving the technological level of the analyst should be carried to guarantee that the measured results are accurate and reliable. When the nickel content is 53.34%,the expanded uncertainty is 0. 14%（expand factor k=2）.