Abstract：Trace impurities in the defining fixed-point metals are usually the most significant source of uncertainty in the realization of ITS-90.A mathematical model is built based on the Scheil equation from the solidification theory to estimate the trace impurities effect on the phase transition temperature of freezing point. The national primary standards of temperature of the fixed point of zinc is studied, the least squares method is used to fit experimental data to estimate the impurities effect on the phase transition temperature. The validity of this method would be proved by chemical analysis. The results show that the phase transition temperature of the zinc freezing point is 0.56 mK higher than the phase transition temperature of the ideal pure zinc since the impurities present, and the higher concentrations of the Ag and Cu in the zinc prove the validity of this method.The foreground of application of this method is better than SIE and OME methods.
孙建平,邓小龙,张金涛. 基于Scheil方程的微量杂质对锌凝固点相变温度影响的评估方法[J]. 计量学报, 2015, 36(2): 136-140.
SUN Jian-ping,DENG Xiao-long,ZHANG Jin-tao. Estimation Method of the Effect on the Transition Temperature ofthe Trace Impurities in Freezing Point of Zinc Based on the Scheil Equation. Acta Metrologica Sinica, 2015, 36(2): 136-140.
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