The normal infrared (IR) spectral emissivity of pure titanium TA1 is experimentally investigated using a self-designed emissivity measurement apparatus. The apparatus and the measurement method are described in detail. Seven samples are treated with abrasive paper to obtain the roughness needed. The emissivity of one sample is obtained between 473 and 1035 K with wavelength range of 3-27 µm in an argon environment. The other six samples are oxidized at a high temperature (873 K) for various times. The surface roughness and composition of the samples are analyzed using roughness tester and X-ray diffraction before and after the emissivity measurement. The results show that the spectral emissivity of titanium sample increases with the increase of temperature and decreases with the increase of wavelength from 3 to 27 µm. For the oxidized samples, the spectral emissivity increases with increasing oxidization time, and after being heated for 12 h, the emissivity values increase slightly. The influence of the oxide film thickness on the spectral emissivity is discussed based on interference theory, and the thickness of oxide film with different oxidation time is accurately measured using scanning electron microscope.
Keywords: Pure titanium; TA1; experimental apparatus; interference; spectral emissivity; surface oxidation.