粉末冶金真空炉专用新型热电偶与在线原位校准

The New Type High-Temperature Sensor for Vacuum Metallurgy and Online Onsite Calibration of the System

从粉末冶金行业的精确生产与优质高效的战略出发,简述粉末冶金行业用钨铼热电偶的特点、分类与使用。详细论述粉末冶金真空炉专用超高真空（10-5 Pa）、超高压（15 MPa）密封式热电偶及炉温均匀性测试等新型传感器。详细探讨真空炉测温准确度的影响因素：真空度、发射率、热导率、热响应时间及热电偶的插入深度、热电偶保护管的选择等;简介进口真空炉专用热电偶国产化研究,国内外温度传感器性能对比及替代进口真空炉热电偶的成功业绩。目前,对测温系统的检定,多采用分立元件法,即对构成测温系统的元件及仪表分别进行检定。此种检定方法是离线的。本文简述离线式检定方法的诸多弊端以及美国宇航标准（AMS 2750E）中,有关系统准确度校准的特点及要求。详细论述在线原位校准的最新理念,最佳的系统准确度校准方案,并开发出与其配套、行之有效的带有校准孔的热电偶及便携式在线校准仪。为了提高测温系统的准确度,建议采用在线原位校准,方便易行,现已在国内推广应用。

From the perspective of precision production and high efficiency in the powder metallurgy industry, the use of WRe thermocouples, their types and characteristics were briefly introduced. The new type sensors including sealed temperature sensors specialized for high pressure （15 MPa） and high vacuum （10 --5 Pa） , and sensors for furnace temperature uniformity survey were discussed. The influence factors of vacuum temperature measurement accuracy： vacuum degree, emissivity, thermal conductivity, response time, and thermocouple insertion depth, as well as the choice of protection tube were investigated. The domestication of thermocouples for imported vacuum furnaces and performance of various temperature sensors were introduced briefly. Currently, the calibration of the temperature measuring system utilizes mostly the discrete element calibration, which calibrate the thermocouple and instrument respectively. This type of calibration is offline. The shortcomings of the offline calibration and the system calibration requirement according to US AMS 2750E were presented. The new idea of online onsite calibration, the best system accuracy calibration solution and the development of pre-calibrated thermocouples and portable online calibration instruments were discussed. In order to improve temperature measuring accuracy, it is recommended to use online onsite calibration instruments, they are convenient and easy to operate, and have started being used in China.