基于高温黑体炉的钨铼热电偶校准方法研究

基于中国计量科学研究院的高温黑体炉设计了一种适用于钨铼偶等高温热电偶的校准方法。优化设计的均温块测温孔轴向均匀性20mm范围内小于0.5℃,优选的测温孔与中心孔的辐射温度差异可达到小于0.5℃。经铂铑10-铂热电偶验证了基于高温黑体炉的校准方法,在800~1300℃与S型热电偶标准热电势间差异小于0.5℃,不确定度评估为0.8~1.5℃,k=2。在800~1900℃范围内,测试了多只不同来源的C型钨铼偶热电势并考核了偶丝校准前后的均匀性,实验结果表明,钨铼偶丝与国际标准钨铼偶热电势的差异基本保持在1%以内,校准不确定度为3.7~13.0℃,相对不确定度为0.7%t (t为温度),k=2。

Calibration of Tungsten-Rhenium Thermocouple Based on High Temperature Blackbody Furnace

A calibration method for high-temperature thermocouples, as tungsten-rhenium couples, was designed based on the high temperature blackbody furnace at the National Institute of Metrology(NIM). The axial uniformity of the optimally designed cavity in the temperature thermostat was measured less than 0.5℃ within 20mm depth. The radiance temperature difference between the selected cavity and the central one was less than 0.5℃. The calibration method based on the high temperature blackbody furnace was verified by Pt-10% Rh/Pt thermocouple. The calibration error from 800℃ to 1300℃ was less than 0.5℃, and the uncertainty was estimated 0.8~1.5℃, k=2. In the range of 800~1900℃, the electromotive force of tungsten-rhenium thermocouple from different manufactures was calibrated, and the uniformity of the wires before and after calibration was also tested. The calibration result showed that the relative error of the tungsten-rhenium thermocouple was kept within 1%, and the uncertainty was estimated 3.7~13.0℃, k=2 which was about 0.7%t in the relative uncertainty.