The porous silicon nitride ceramics with low dielectric constant, high strength were obtained using SiO2 hollow balls as pore-forming agent by gel casting. The porosity and pore size of the sample can be controlled by changing the size and amount of pore-forming agent added. The results show that the porosity of sample rises with the increase of the amount of pore-forming agent, but the flexural strength decreases, the dielectric constant and the dielectric loss of the sample also decrease, and the minimum dielectric constant is about 1. 77. When the mass fraction of pore-forming agent added is 10%, with the increase of the size of the pore-forming agent, the pore size in the sample increases but the flexural strength decreases, the dielectric constant and the dielectric loss of the ceramic decrease too. The porous silicon nitride ceramic obtained by adding 10% 80m pore-forming agent is suitable for the core of broadband radome with the dielectric constant is 2. 13 and the flexural strength is 38MPa.%采用凝胶注模成型工艺,以SiO2含量大于等于95％的空芯玻璃微珠作造孔剂,通过控制造孔剂的加入量和调节造孔剂的孔径成功制备出低介电常数、高强度的多孔Si3N4陶瓷.结果表明,随着造孔剂含量的增加,试样气孔率增大,弯曲强度降低,ε和tanδ都相应降低,ε最低为1.77;在造孔剂加入量为10％时,随着造孔剂的孔径尺寸变大,试样的孔径变大,弯曲强度降低,试样的ε和tanδ也相应降低.当造孔剂含量为10％、孔径尺寸为80μm时制备的多孔氨化硅陶瓷ε为2.13,弯曲强度达到38MPa,适合作为宽频带天线罩的夹层材料.
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