金属外壳水三相点容器

Triple Point of Water Cells with Metal Containers

水三相点是ITS-90国际温标中最重要的定义固定点,其复现不确定度是传递到整个温标的。目前,通常采用不同的冻制方法在硼硅玻璃或石英水三相点容器内冻制均匀的冰套来复现水三相点。冻制过程中,由于在水三相点容器内生成冰桥,会造成容器的破裂。为了解决此难题,研制了金属外壳水三相点容器,利用高纯水自发相变原理,在液体槽内自动冻制水三相点。通过与硼硅玻璃水三相点容器的比对,证实金属外壳水三相点容器可以满足标准铂电阻温度计校准及其他温度传感器期间核查的需求。实验结果表明:4个金属外壳水三相点容器与普通玻璃水三相点容器复现的水三相点在0.04 mK范围内一致。

The tripe point of water(TPW)is the most important defining fixed point in the International Temperature Scale of 1990(ITS-90),and its realization uncertainty is propagated the whole temperature scale.At present,different freezing methods are adopted to form uniform ice mantles in the borosilicate glass or quartz TPW cells to realize the TPW.Because the ice bridges can happen during the freezing procedure,which can rupture the cells.In order to solve the problem,the TPW cells with metal containers are developed.Using the principle of spontaneous phase transition of high purity,the TPW is automatically realized with a liquid bath.Comparison between the metal-cased cells and the borosilicate glass cell confirmed that the TPW cells with metal containers can meet the requirements for calibration of the standard platinum resistance thermometers and check for the other temperature sensors during the calibration intervals.The experimental results show that the temperature differences between the four metal cased cells and the conventional borosilicate glass cell are within 0.04 mK.