锌凝固点的比较

The Comparison of the Freezing Point of Zinc

哈特公司为建立锌的凝固点专门设计了一种密封容器，这种客器有诸多优点，例如使用方便，寿命较长等。纯度为９９．９９９９％的锌样品放入石墨坩锅后被封入一个充满纯氩气的熔融石英容器中，经测定，其复现性为０．２４ｍＫ。本文概述了实现固定点的方法，并将测试结果与经ＮＩＳＴ标定过的标准铂电阻温度计的结果进行了比较，二者之间数据之差小于０．３ｍＫ．凝固点附近的扩展不确定度（包含系数ｋ＝２）为１．０ｍＫ，满足ＮＩＳＴ最高准确度的要求．

A Specially designed hermetically sealed cell was developed forestablishing the freezing point of zinc at Hart Scientific.This sealed cell hadmany advantages such as ease of use and long life expectancy.A zinc sampleof 99.9999% p.urity was placed into a graphite crucible then enclosed in afused silica cell with a pure argon atmosphere. The reproducibility was determined to be 0.24 mK.This paper outlines the procedure used in realizingthe fixed point and compares the test results with a NIST calibratedSP RT.The difference between Hart's data and NIST's was well within 0.3mK.The expanded uncertainty(coverage factor k = 2) at the point was 1 .0 mKsatisfying NIST's most stringent accuracy class requirements.