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采用凝胶注模成型工艺制备了SiC_w/Si_3N_4复合陶瓷,由扫描电镜(SEM)可以看出,随热处理温度升高,碳化硅晶须的长径比逐渐减小;随烧结温度升高,复合陶瓷开孔率降低,密度随晶须含量的增加而增加。研究表明,SiC_w/Si_3N_4复合陶瓷的介电常数实部和虚部随碳化硅晶须含量的增加而升高,当烧结温度为1600℃,晶须含量从5%增加到15%时,8 GHz时介电常数实部从13.4增加到22.8,虚部从0.67增加到4.86;当烧结温度为1750℃时,8 GHz时介电常数实部从9.2增加到21.7,虚部从0.51增加到3.02。由反射率曲线可以看出,烧结温度为1750℃比1600℃时反射衰减随晶须含量的增加向低频移动的更快,频宽更宽。
The SiC_w / Si_3N_4 composite ceramics were prepared by gelcasting. The scanning electron microscope (SEM) shows that the aspect ratio of silicon carbide whiskers decreases with the increase of the heat treatment temperature. With the increase of the sintering temperature, Porosity decreases with increasing ceramic whisker content. The results show that the real and imaginary part of the permittivity of SiC_w / Si_3N_4 composite ceramics increase with the increase of silicon carbide whisker content. When the sintering temperature is 1600 ℃ and the whisker content increases from 5% to 15%, the dielectric constant of SiC_w / When the sintering temperature is 1750 ℃, the real part of dielectric constant increases from 9.2 to 21.7 at 8 GHz, and the imaginary part increases from 0.51 to 3.02 at 1750 ℃. It can be seen from the reflectance curve that the reflection decay shifts faster and broaden to lower frequency with the increase of whisker content at the sintering temperature of 1750 ℃ and 1600 ℃.