摘要
介绍了一种基于延长石墨衬套和预先形成共晶体的灌注新方法。为改善沿固定点的温度梯度，同时避免相变过程中的热应力集中，坩埚设计上引入混合结构，即在石墨衬套和坩埚间引入导热各向异性的高纯石墨箔。同时采用延长型石墨衬套，有效地减少灌注次数，降低外界杂质引入的可能。国际温度咨询委员会辐射测温工作组（CCT-WG5）对于定义热力学温度用最高等级Co-C固定点的要求重复性在20mK以内，熔化结束温度与起始温度差〈120mK。基于新灌注方法灌注的Co-C共晶高温固定点，初步复现结果表明，相变温度1324．054℃，其短期重复性在9mK以内，熔化结束温度与起始温度差〈110mK，满足CCT—wG5对固定点的要求。
A new construction method based on an extended graphite sleeve and pre-forming eutectic is described. In order to improve the temperature gradient along the HTFP cell and avoid thermal stress concentration in the process of phase transition, the crucible is designed hybrid structure, namely, placing the high purity graphite foil with anisotropic thermal conductivity between the graphite sleeve and crucible. Meanwhile it can reduce the filling times effectively which can decrease the introduced external contaminants by using the extended graphite sleeve. CCT-WG5 （ Consultative Committee for The^nometry, Working Group 5 ： Radiation Thermometry） for the definition of thermodynamic temperature with the highest level of Co-C eutectic HTFP demands the repeatability is better than 20 mK and the difference between the initial temperature and the end temperature of melting is less than 120 mK. A new Co-C eutectic HTFP was constructed based on the new filling method, and the preliminary results show that the phase transition temperature is 1324. 054℃, short-term repeatability is better than 9 mK, and the difference between the initial temperature and the end temperature of melting is less than 110 mK, which meet the CCT-WG5 requirements for the HTFPs.
出处
《计量学报》
CSCD
北大核心
2011年第B12期58-61,共4页
Acta Metrologica Sinica
关键词
计量学
辐射测温
高温固定点
Co—C共晶
灌注
Metrology
Radiation thermometry
High temperature fixed-point
Cobalt-carbon eutectic
Filling
