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The Annealing Effect on the Performance of the Standard Platinum Resistance Thermometer |
DENG Xiao-long1,SUN Jian-ping2,YUE Kai1,LI Jie3,WU Xin-cai3 |
1. University of Science and Technology Beijing, Beijing 100083, China;
2. National Institute of Metrology, Beijing 100029, China;
3. Hebei University, Baoding Hebei 071000, China |
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Abstract Annealing is the most effective means to eliminate internal stress of SPRT that is due to factors such as mechanical vibration.At the same time, it may change the internal oxidation state of platinum wire.Four SPRTs from different countries are chosen,these SPRTs are annealed at five different temperatures (600 ℃、500 ℃、450 ℃、420 ℃、350 ℃) for 4 hours to investigate their stability at room temperature after annealing.The results show that different annealing temperature can produce different effects on resistance of thermometers,equivalent to temperature changes maximum 1 mK,the water triple point resistance changed significantly in 0 to 6 hours, to keep the platinum resistance thermometer in a same thermal state can effectively improve the temperature measurement level.
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