大温度梯度下含锆型硅酸铝纤维板的透波性能

Wave transmission performance of zirconium aluminum silicate fiberboard under large temperature gradient

为探究微波冶金反应器内常用隔热保温材料——含锆型硅酸铝纤维板(ZAF)在温度梯度下的透波性能,首先采用谐振腔微扰法测量了ZAF在25~1000℃范围内的复介电常数;其次采用激光闪射法测量了ZAF在100~500℃范围内的热导率;最后基于电磁波传输线理论和传热理论研究了ZAF在频率、极化模式、入射角度及材料厚度等因素影响下的透波性能。结果表明:ZAF的介电常数随温度的增加整体变化幅度较小,介电损耗因子则在900℃之后呈指数型增大;ZAF的热导率随温度的增大而逐渐增加,其上升幅度约为39.65%;在2450MHz频率下,ZAF的功率透过系数大于0.9的比例要高于915MHz频率,且在相同频率下,水平极化模式(TM)的透波性能优于垂直极化模式(TE);随着ZAF厚度的增加,其功率透过系数曲线出现了多个透波峰,且2450MHz频率下的透波峰数量多于915MHz频率;在TE极化模式下,微波以0°~30°入射时材料具有良好的透波性能,在TM极化模式下,微波以0°~60°入射时材料具有较高的透波性能,并且存在能使微波发生全透射的布儒斯特角。

In order to investigate the wave transmission performance of zirconium aluminum silicate fiberboard(ZAF),a commonly used thermal insulation material in microwave metallurgical reactor under temperature gradient,the complex permittivity of ZAF at 25—1000℃ was measured by cavity perturbation method.Secondly,the thermal conductivity of ZAF in the range of 100—500℃ was measured by laser flash method.Finally,based on the electromagnetic transmission line theory and heat transfer theory,the wave transmission performance of ZAF under the influence of frequency,polarization mode,incident angle and material thickness were studied.The results showed that the dielectric constant of ZAF changed slightly with rising temperature and the dielectric loss factor increased exponentially after 900℃.The thermal conductivity of ZAF increased with the increase of temperature,and the increase rate was about 39.65%.At 2450MHz,the fraction of the ZAF greater than 0.9 power transmission coefficient was higher than at 915MHz,and at the same frequency,the wave transmission performance of the transverse magnetic polarization mode(TM) was superior to the transverse electric polarization mode(TE).Multiple transmission peaks developed in the power transmission coefficient curve as ZAF thickness increased,and there were more wave transmission peaks at 2450MHz frequency than at 915MHz frequency.When the microwave incidence angle was between 0°—30° in the TE polarization mode,the material exhibited good wave transmission performance.When the microwave incident angle was between 0°—60° in the TM polarization mode,the material exhibited good wave transmission performance,and there was a Brewster's angle where the microwave can transmit entirely.For the study of wave transmission performance of thermal insulation materials under temperature gradient,this study offered a crucial reference value.