用于阻抗变换层的Li2O-Al2O3-SiO2玻璃陶瓷制备及其微波介电特性

 采用热压和凝浇注无压烧结的方法制备了Li₂O-Al₂O3-SiO₂ 玻璃陶瓷阻抗变换层,研究表明烧结的工艺方法和参数对该玻璃陶瓷的致密度和复介电常数有很大的影响。在较高烧结温度和压力下,该玻璃陶瓷的复介电常数保持不变。降低烧结温度和压力时,能够得到一系列复介电常数在较小范围内变化的Li₂O-Al₂O₃-SiO₂ 玻璃陶瓷,但复介电常数不随频率发生变化。将该玻璃陶瓷作为吸波材料的阻抗变换层后,大幅度提高了材料的吸波性能,而且其制备工艺对吸波性能也有一定的影响,可以通过改变该玻璃陶瓷的烧结条件来满足不同吸波材料设计对阻抗匹配层的多种要求。

Preparation and Microwave Dielectrical Properties of Li2O-Al2O3-SiO2 Glass-Ceramic Used as an Impedance Transfer Layer of Microwave Absorbing Materials

The low thermal expansion coefficient and the moderate permittivity of Li 2O-Al 2O 3-SiO 2 glass-ceramic make it possible to be used as an impedance transfer layer of radar wave absorbing materials to increase the microwave absorbing efficiency and expand absorbing bands. But a series of accurate permittivities of impedance transfer are needed to meet the impedance matching design. Therefore, the relationship between permittivity of the glass-ceramic and sintering conditions was studied. The results showed that the real and imaginary parts of permittivity of the glass-ceramic increase with the sintering densities, and no frequency dependency of permittivity was found. The reflectivity-frequency curves illustrate that the attachment of the glass-ceramic to the microwave absorbing materials greatly reduces the materials' reflectivity to microwave and a little change of permittivity of the glass-ceramic can also exert a remarkable influence on microwave absorbing materials. So an expected permittivity of the glass-ceramic is needed and can be obtained by varying sintering conditions of the glass-ceramic.