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Radiation mechanism of ceramic materials

wallpapers News 2021-06-03
Radiation mechanism of ceramic materials
The radiation mechanism of ceramic materials is generated by two photons and multiple phonons of the nonresonant effect of random vibration. High radiation ceramic materials such as silicon carbide, metal oxide, boride infrared active polarity are very strong in vibration, the vibration due to the polarity has greatly strengthened the anharmonic effect of the absorption coefficient of the double frequency and frequency area, generally with 100 ~ 100 cm - 1 order of magnitude, absorb the equivalent of the moderate-intensity area in the residual reflection area with low reflectivity, therefore, It is conducive to the formation of a relatively flat strong radiation belt.
Generally speaking, the radiation band with high thermal radiation efficiency extends roughly from the strong resonance wavelength to the whole two-phonon combination and frequency region of the short-wave, including part of the multi-phonon combination region. This is the common feature of most radiation bands of high-radiation ceramic materials. It can be said that the strong radiation band is mainly derived from the two-phonon combination radiation in this band. With a few exceptions, the radiation bands of radiant ceramics are concentrated in the diphoton and triphonon regions larger than 5m. Therefore, for infrared radiation ceramics, the radiation in 1~5m bands is mainly from the in-band transition of free carriers or the direct transition of electrons from impurity level to conduction band, and the radiation larger than 5m band is mainly attributed to the two-phonon combination radiation.
The infrared emissivity of the ceramic samples tested was about 0.82~0.94. The infrared emissivity of the far-infrared ceramic glaze with different surface qualities was also tested, and the emissivity was about 0.6~0.88. And from the SEM photos of the ceramic fracture, it was found that the radiation property, glaze quality, color and cost of the far-infrared ceramic powder were better when the amount of the far-infrared ceramic powder was added to the glaze at 10wt%. The radiation rate reached 0.83, and other properties met the requirements of the national standard for daily use porcelain. Cui Wanqiu and Wu Chunyun tested the far-infrared ceramic block samples at low temperatures, and the infrared emissivity was 0.78~0.94. Li Hongtao and Liu Jianxue found that the emissivity of far-infrared ceramics at room temperature was generally 0.85, and the highest emissivity of foreign Enecoat glaze coatings was 0.93~0.94. Many studies have shown that the ceramic material or glaze itself has a very high infrared emissivity, which is an important parameter to replace the traditional aluminum radiator.
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