基于微型高温共晶点的钨铼热电偶原位赋值方法探索

Reliable high temperature (>1100 ℃) measurement under special conditions is a hot and difficult problem in many fields of industrial process control. This research is based on international new idea of the application of metal-C eutectic as the high temperature fixed point in the contact thermometry, and aims to develop the in-situ value assignment temperature sensor of tungsten-rhenium thermocouple integrated with the miniature high-temperature fixed point. This work will concentrate all of my research on the thermal characteristics of in-situ value assignment tungsten-rhenium thermocouple for revealing the mechanism of effect of the extreme thermal environments, thermal history and size of fixed point on the phase change temperature of the eutectic fixed point. Numerical relationship between static and dynamic state temperature condition, temperature gradient condition, solidification rate and melting phase change temperature will be built, and the failure condition of in-situ value assignment tungsten-rhenium thermocouple will be obtained. Through utilizing the structure characterization technique and component analysis technique of material, the effect of the precipitation, diffusion and chemical reaction behavior of the component materials on the in-situ value assignment of thermocouple will be researched in high temperature environment. This research can provide the important theory evidence and technical support for the high temperature eutectic fixed point applied to the in-situ value assignment of tungsten-rhenium thermocouple, promote the development of ITS-90 and high temperature thermoelectric materials science, and meet the demand of the high temperature measurement traceability and Constantly improving the high temperature measurement level in domestic many fields, especially aerospace.

特殊环境下可靠的高温测量（>1100℃）是当前工业多个领域过程控制所面临的热点和难点问题。本项目基于国际上将金属-碳共晶体作为高温固定点应用于接触测温领域的新思路，研制微型高温共晶点与钨铼热电偶直接结合的原位赋值温度传感器，集中开展基于微型高温共晶点原位赋值钨铼偶的热特性研究，揭示极端热环境、热历史及尺寸效应对共晶点相变温度影响机理，建立静态温度环境、动态温度环境、温度梯度、凝固速率与熔化相变温度影响的量化关系，研究原位赋值钨铼偶的失效条件；利用材料结构表征技术及成分测量技术，开展高温环境下组件材料析出、扩散、化学反应行为对原位赋值热电偶影响机理的研究，为高温共晶点应用于钨铼偶原位赋值提供重要的理论和技术支撑，促进ITS-90国际温标及高温热电材料科学的发展，满足国内多个领域尤其是航空航天高温测量的溯源及不断提升的精度水平的需求。

特殊环境下可靠的高温测量（>1100℃）是当前工业多个领域过程控制所面临的热点和难点问题。本项目基于国际上将金属-碳共晶体作为高温固定点应用于接触测温领域的新思路，研制基于高温共晶点与钨铼热电偶直接结合的原位赋值温度传感器。开展微型高温共晶点与钨铼热电偶原位赋值方法研究，评估预期不确定度，探索多固定点与钨铼热电偶结合实现原位赋值的可能性，为发展高温原位赋值温度传感器提供技术铺垫。结果表明对于所研制的Pt-Pd-C共晶点，钨铼热电偶在Pt-C共晶点的校准不确定度为3.4℃（k=2），在Pd-C共晶点校准不确定度为3.0℃（k=2）。利用热力学和金属熔化、凝固及扩散基础理论，通过数值模拟深入开展基于微型高温共晶点原位赋值钨铼偶热特性研究，结合微型相变固定点不同热环境及热历史的实验验证，揭示极端热环境和尺寸效应对共晶点相变温度影响机理；利用材料结构表征技术及成分测量技术，开展高温环境下组件材料析出、扩散、化学反应行为对原位赋值热电偶影响机理的研究，为高温共晶点应用于钨铼偶原位赋值提供重要的理论和技术支撑。