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| New Automatic Apparatus of the Melting Point of Gallium |
| SUN Jian-ping1,2,CHEN Wei3,QIU Ping2,LIU Jian-qing3,ZHANG Xin-xin1 |
1. University of Science and Technology Beijing, Beijing 100083, China;
2. National Institute of Metrology, Beijing 100013, China;
3. Hebei University, Baoding, Hebei 071002, China |
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Abstract A new apparatus of the melting point of gallium is developed in National Institute of Metrology.The melting point of gallium can be realized automatically by the fixed point furnace with the three-zone freezing and heating technique.The excellent stability and uniformity of the fixed point furnace is obtained because of the precise temperature control and the reasonable design.The cell of the gallium melting point is filled with the 99.99999% purity gallium that is purified by the present technique and improved perfusion technique.The experiment results show that the plateau of the apparatus lasts more than 70 hours,and the difference of the plateau from 20% to 80% is less than 0.15 mK.The reproducibility of the apparatus is 0.07 mK,and the expanded uncertainty is 0.36 mK(k=2).
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2013, Vol. 34 
