| The emissivity is an important parameter which describes the thermal radiative property of material, and it has a wide application in the aeronautics, astronautics, national defence, science research, industry, agriculture and other research fields. For example, the radiative characteristic of aerospace crafts and satellite is important for temperature controlling when they fly in the airspace. The radiative characteristic of missile plume and skin is a necessary parameter in the antagonism between the infrared guided weapon, and the radiative characteristic of military targets also has a critical effect on the attack and hiding of military targets. On the other hand, in the field of food supplies, oil paint, leather drying and electric heating, the control of the radiative characteristic of heating target is an important technique for the decrease on energy consumption and increase on production efficiency. In the radiative temperature measurement, the radiative is a necessary prior parameter before the true temperature is known, so the problem of the measurement of radiative is a bottle-neck in the radiative temperature research.The emissivity not only depends on the components of material and surface state (such as roughness, oxidation), but also on the temperature and wavelength measured. The emissivity is not a characteristic parameter of material itself, but it varies with the external condition. Lots of studies had done much research, and provided many useful methods, and developed all kinds of equipment as well. But the level of emissivity measurement is not satisfactory, the dispersity of data is larger, and we are at the initial step. The research comes from the project of National Natural Science Foundation of China and Aerospace Research Institute of Materials & Processing Technology. The purpose of this project is to research the spectrum emissivity according the measurement equipment based on Fourier transform spectrometer. The finished research works are as follows:1. A new measurement equipment has been researched based on the Fourier transform spectrometer. The stove for heating specimen, reference blackbody stove, light path with condenser mirror, cavity body at constant temperature and vacuum system have been designed. This system can work in spectral range from 0.6μm to 25μm and in the temperature range from 60℃to 1500℃, and the measurement precision can get to 3%.2. A new method for compensating the influence of surrounding radiation has been proposed. At the infrared spectral region, the stray radiation from surrounding may be comparable to target's radiation, and the surrounding radiation contains the radiation inside the instrument and the radiation outside the instrument. The two kinds of radiation can come into the instrument by some couple mode, which will have a bad effect on the measurement results. So the new method for compensating the influence of surrounding radiation by twice measurement eliminates the influence of surrounding radiation effectively.3.A new method for temperature measurement has been proposed based on the Wien displacement law. First, the radiant spectral curve of target can be measured by a Fourier transform spectrometer, second, the peak value of curve can be found and corresponding wavelength must be marked. Third, the temperature of target can be calculated by Wien displacement law. We call this method as Peak Wavelength Method-PWM. For blackbody surface and real surface, theoretical and experimental analysis on the uncertainty is done, and a set-up is constructed and tested. They prove that PWM method has a high accuracy and practicability.4. A series of experiments have been done using the apparatus developed to measure the spectral eimssivity of materials. The results show that the data measured agree well with the data from literature. In the end, the uncertainty has been estimated for this apparatus and its result also proves this measurement system can satisfy the design demand.
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