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用溶胶-凝胶法制备了质量比m(Al_2O_3)/m(SiO_2)分别为72/28、74/26和76/24(称为样品72/28、样品74/26和样品76/24)不同组成的莫来石单相胶,将单相胶在1 000℃下热处理2h,然后用放电等离子烧结技术分别在1 450、1 500、1 550℃烧结10 min,样品相对密度均可达97%以上。对烧结体的微观结构进行扫描电镜分析,结果表明:随着先驱体组成中SiO_2含量降低,长轴晶的形成温度升高。3种样品的红外透波率均随烧结温度的上升而下降,其中样品72/28由于晶粒大小和气孔尺寸均较小,其透波率均高于相应烧结温度的另外两个样品。样品74/26在1 550℃烧结时,由于形成的长轴晶的直径与红外波长相当致使散射损失严重,透波率急剧下降,而样品76/24由于等轴晶的尺寸与红外波长相当,再加上第二相的形成造成的散射,使其透波率均较低。
The mass ratios m (Al_2O_3) / m (SiO_2) were 72/28, 74/26 and 76/24 (referred to as sample 72/28, sample 74/26 and sample 76/24) Different composition mullite single-phase glue, the single-phase glue at 1000 ℃ heat treatment 2h, and then by spark plasma sintering technology at 1 450,1 500,1 550 ℃ sintering 10 min, the relative density of the sample up to 97 %the above. The microstructure of the sintered body was analyzed by scanning electron microscopy. The results show that the formation temperature of long axis crystal increases with the decrease of SiO 2 content in the precursor. The infrared transmittance of the three samples decreased with the increase of the sintering temperature. The samples 72/28 had the higher transmissivity than the other two samples with the corresponding sintering temperature due to the smaller grain size and pore size. When the samples 74/26 sintered at 1 550 ℃, the scattering loss was serious due to the diameter of the long axis crystal formed corresponded to the infrared wavelength. The sharp decrease of the transmission rate was observed. However, due to the size of the equiaxed crystal being equal to the infrared wavelength, Coupled with the scattering caused by the formation of the second phase, so that its permeability are lower.