Abstract Au/Pt thermocouples are considered as an alternative to High Temperature Platinum Resistance Thermometers and are one of the prime candidates to replace them as the interpolating instrument of the International Temperature Scale of 1990 (ITS-90) in the temperature range between about 660 °C and 962 °C. This work presents the results of investigation of two Au/Pt thermocouples that used exclusively quartz glass (SiO2) as insulation material. Measurements in fixed points of Zn, Al, and Ag were realized on these thermocouples as well with interchanged inner insulation made of high purity aluminium oxide (Al2O3). The conducted experiments tested the performance of Au/Pt thermocouples with the use of different insulation materials. The measured electromotive forces were found to be sensitive to the replacement of the quartz glass by aluminium oxide as an insulation material of the Au/Pt thermocouples. This change of insulation has resulted in a temperature increase up to about 0.5 K measured at the freezing point of silver. The decreasing insulation resistance of quartz glass at higher temperatures is believed to be the source of thermoelectric instability.

中文翻译：

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石英玻璃绝缘对铂金热电偶的影响

摘要 Au/Pt 热电偶被认为是高温铂电阻温度计的替代品，是取代它们作为 1990 年国际温标 (ITS-90) 在约 660° 之间的温度范围内的插值仪器的主要候选者之一。 C 和 962 °C。这项工作展示了对两个专门使用石英玻璃 (SiO2) 作为绝缘材料的 Au/Pt 热电偶的研究结果。在这些热电偶上实现了 Zn、Al 和 Ag 固定点的测量，以及由高纯度氧化铝 (Al2O3) 制成的可互换内部绝缘材料。所进行的实验测试了使用不同绝缘材料的 Au/Pt 热电偶的性能。发现测量的电动势对用氧化铝代替石英玻璃作为 Au/Pt 热电偶的绝缘材料很敏感。绝缘的这种变化导致在银的凝固点测量的温度升高高达约 0.5 K。石英玻璃在较高温度下的绝缘电阻降低被认为是热电不稳定性的来源。