Study Of Phase Transition Characeristics And Applications Of Mini Ga-In-Sn Eutectic Fixed Point

Temperature measurement is an accurate and reliable activity to achieve unity and value transfer.Extreme conditions including high temperatures,high pressures,vibrations,strong electromagnetic fields,and so on can cause the transmission failure of temperature metrology standard.At present,the application of the transfer technique of the primary temperature fixed-point in the industrial field is an international trend.This research is a part of the project of the National High Technology Research and Development Program of China(863)“ "Development of High-Precision Spatial Infrared Radiation Reference Source".The phase transition characteristics at different conditions,as well as the flow characteristics of Ga-In-Sn ternary alloys,are the main focus of this dissertation.The main contents of this dissertation is as follows(1)the development of miniature Ga-In-Sn fixed point that can be used in the field calibration(2)the mechanism study on hypoeutectic and hypereutectic phase transition under different ratios(3)the reproducibility of miniature Ga-In-Sn fixed point devices.The influence of solidification rate and melting temperature on the phase transition temperature,supercooling,and the flow characteristics of eutectic materials of different ratios.The results showed that the melting plateau can last 1.2 h~2 h,the reproducibility is better than 4.5 mK,and the uncertainty is 9.3 mK(k=2).In order to meet the requirement of in-field operation,smaller supercooling is essential.Gallium is the main component in the eutectic alloy,so the supercooling is determined by the corresponding properties of Gallium.It has been found that the cooling rate,the setting temperature time,and temperature after melting are the main factors affecting the eutectic point's supercooling.The viscosity of ternary Ga-In-Sn and quaternary alloy Ga-In-Sn-Zn was measured respectively and compared with literature data.The experimental results showed that the viscosity of the ternary alloy is 20% higher than that of mercury which showed that the alloy is not the ideal substitute for mercury.Given the effects of impurities on the thermophysical properties of the alloy,the proper extra metal could be added to improve the flow characteristic of the alloy.The results will provide basic data for the study of clinical thermometers.