用一系列含碳量(wC)在0.002%~0.03%范围内的标准物质在直读光谱仪上按选定的工作条件测定各样品的碳量。根据所得每一样品的一系列测定值以及各项统计量,分析并判断了直读光谱法在测定钢板中超低碳含量的准确度和精密度水平。试验结果表明:① 测定结果的准确度受样品的基体背景及仪器标准化条件的影响,引入了系统误差;据此建议选择与待测样品基体匹配的标准物质校准仪器并选择合理的仪器标准化条件。② 在上述含碳量范围内,所得测定值的S%值(包括10次测定和5次测定的计算值)差异较小,其极值之差为3×10-4%,但对相对标准偏差有显著影响,其最低值在2%左右,而最高值达21%。③ 在所选定的测定条件下,对碳含量在10-5数量级的样品而言,准确度或系统误差的波动范围在±1×10-4%范围内。

A set of CRM′s with values of wC% ranged from 0.002% to 0.03% was analyzed for their carbon contents with a direct reading AES under the specified working conditions. A statistical study was made based on data obtained, i.e., the values of wC% of each of the CRM′s and their statistics and levels of accuracy and precision of the method for determination of ultra-low carbon in steel sheets were assessed. It was shown that: ① accuracy of the analytical results was affected by the matrix background of individual sample and standardization condition of the instrument, it is advised to choose CRM′s having similar composition with the sample for calibration of instrument and rational condition of standardization;② in the range of carbon content concerned, only small differences among values of S% (either for n=5 or 10) were obtained with difference of extreme values of 3×10-4%, but significant differences of values of RSD% were observed with min. and max. values of 2% and 21% respectively;and ③ range of fluctuation of systematic error (or of accuracy) for determination of carbon content at the magnitude of 10-5 attained to values ranged in ±1×10-4%.