Study On The Characterististics Of Melting Spectral Emissivity Of Fe-Ni Alloy

Spectral emissivity is an important parameter to characterize the thermophysical properties of materials.It is important that spectral emissivity is applied in radiation temperature measurement,thermal radiation transmission,metal smelting,aerospace,infrared stealth,and other fields.In recent years,researchers have mainly focused on the measurement of spectral emissivity of solid non-transparent materials at home and abroad.The spectral emissivity of a large number of substances was measured.There were relatively little research on the spectral emissivity of high temperature metals,semiconductors and alloys,especially high temperature molten metals.The spectral emissivity of molten metal has important applications in the research and development of special metal materials,high-precision online radiation temperature measurement and other fields.The traditional crucible measurement devices for measuring the normal spectral emissivity of melts was built based on the energy contrast method.The device consisted of a sample heating furnace,a blackbody,an optical path system,a spectrometer,and a colorimetric pyrometer et al.The system linearity test and fitting residual distribution were carried out on the built measurement device,which proved that the test system has a good linearity.The melting spectral emissivity of liquid pure copper in the range of 1000-1600 nm was measured to verify the reliability of the melting spectral emissivity measurement system.Comparing the measured spectral emissivity data with the simulation data of the Drude free electron model at the melting point of copper,it is found that the trends of both are consistent.By comparing with foreign related literature,it is found that the measured emissivity data of pure copper are in good agreement with the literature data,which proves the reliability and accuracy of the measurement system.The spectral emissivity of molten metal is one of the important parameters in the numerical simulation of containerless process and production process.Real-time measurement of the spectral emissivity of molten metal is of great significance to further study the solidification process,microstructure evolution and mechanical properties at high temperature.Iron-nickel alloy is an important metal,which is widely used in automobile,aviation and other industries.The spectral emissivity of molten nickel-iron alloys is helpful to deeply study the thermal properties of metals during melting and solidification,which is of great significance to the study of alloy properties.The dissertation uses the constructed device to measure the melting spectral emissivity of a series of iron-nickel alloys(Ni,Fe10Ni90,Fe30Ni70,Fe50Ni50,Fe70Ni30,Fe90Ni10 and Fe).The effects of wavelength,temperature and composition on the normal spectral emissivity of Fe-Ni alloy melt were studied.The results show that the melting normal spectral emissivity of iron-nickel alloys basically does not change with temperature,but gradually decreases with the increase of wavelength.It has the greatest influence on the melting normal spectral emissivity of iron-nickel alloys.Among all the tested samples,the spectral emissivity of nickel is the largest,while that of Fe30Ni70 is the smallest.The melting normal spectral emissivity of metal nickel and iron in the range of 1000-1600 nm is simulated numerically,and it is found that the theoretical value are in agreement with the experimental value.Finally,the uncertainty of the spectral emissivity of molten pure iron was analyzed,and the maximum uncertainty of the system is better than 1.11%.