Uncertainty Investigation On Measuring Thermal Expansion Coefficient Of Solid Materials By The Interferometry

Thermal expansion coefficient (TEC) is one of the important parameters for thermophysical properties of material. Precise measurement of thermal expansion coefficient is significant for the study of basic science, technological innovation, and practical application.Base on the interferometric dilatometer for solid materials that was devised in National Institute of Metrology, the dissertation aims at repeatability experiment and uncertainty analysis for this device, which would provide the basis for the improvement of the device, establishing the standard device and the traceability of thermal expansion coefficient.The main contents of this dissertation is that the TEC of NIST reference material SRM 738 and silicon are measured with temperature at room temperature,300℃,600℃,800℃, the measurement data are compared with those of developed countries, the influencing factors are discussed, and uncertainty is particularly analyzed.In accordance of repeatability experimenting at different temperature, the relative standard deviation of measurement result is within 1%. The analysis shows that the repeatability of this device is better.The TEC of SRM 738 and silicon are measured with temperature ranging from room temperature to 1200K for examining the reliability of this device. The relative deviation of the data International comparisons is within 3%.Base on the experimentation, the influencing factors including the fluctuating signal, expansion of the optical components, the temperature grads, the heating speed and pedometer are discussed in this dissertation, then this device is developed, simultaneity a new automatic measurement software has been developed, which has more complete function and been expediently operated. These studies are valuable for improving this device in the future.Lastly, the uncertainty is particularly analyzed. The result shows that the main parts of the uncertainty are temperature and expansion of the optical components.According to above conclusions, some feasibility advices are offered for farther improving this device and measurement technology.