莫来石陶瓷的制备及其微波介电性能研究

Preparation and Dielectric Properties of Mullite Ceramic

用 Si O2 溶胶和 Al2 O3 溶胶以及分析纯 Si O2 和 Al2 O3 粉末 ,采用热压烧结法制备了莫来石陶瓷。研究了莫来石陶瓷的微波介电特性与烧结致密度、烧结助剂 Mg O以及测试频率之间的关系。结果表明 ,烧结条件对莫来石陶瓷致密度和介电常数有很大影响 ,其中以热压温度对莫来石陶瓷烧结致密度和复介电常数的影响最大。烧结条件不同时 ,可以得到一系列具有不同复介电常数的莫来石陶瓷。添加烧结助剂 Mg O后 ,莫来石陶瓷复介电常数的实部和虚部均有所升高。在 8～1 2 GHz频率范围内 ,莫来石陶瓷的复介电常数没有表现出明显的频散效应。

Mullite ceramic samples were prepared by hot pressing method in two different ways: (1) from a mixture of SiO 2 sol and Al 2O 3 sol, (2) from a mixture of SiO 2 powder and Al 2O 3 powder. The influences of sintering conditions and sintering additive MgO on the permittivity of the mullite ceramics were experimentally determined and then discussed. The permittivities of the mullite ceramics were measured in the frequency range of 8.2~12.4GHz by the usual method that was based on the measurements of the reflection and transmission module in the fundamental wave guide mode TE10, using rectangular samples (10.16 mm×22.86 mm×2.00 mm). The results show that the sintering conditions dominate the sintering density and permittivity of the ceramics to a certain extent. The real part of the permittivity of the mullite ceramics increases from 3.85 to 5.87 and its imaginary part from 0.04 to 0.11 when the density of the samples increases from 91.4% to 97%. The real and imaginary parts of the permittivity of the mullite ceramics also increase with the addition of MgO. The permittivity of the samples does not show frequency dispersion effect in the tested frequency range.