空心石英纤维增强氮化物基低介电复合材料的制备及其性能

Fabrication and Properties of Hollow Silica Fiber Reinforced Nitride Composites of Low Dielectric

以环硼氮烷和全氢聚硅氮烷组成的混杂先驱体为原料,采用先驱体浸渍-裂解工艺制备了空心石英纤维增强氮化硼-氮化硅混杂基体的复合材料,研究了裂解温度对复合材料的致密化、力学性能、介电性能和断口显微形貌的影响。结果表明,当裂解温度从300℃提高到500℃时,复合材料的密度逐渐增大,材料的弹性模量随之提高,而其弯曲强度先增后减。当裂解温度为400℃时,复合材料表现出最高抗弯强度(132.4MPa),这源于较小的纤维损伤以及基体和纤维之间良好的界面结合状态。随着裂解温度的提高,复合材料的介电常数也逐渐增大,但三种温度下制备的复合材料均具有较低的介电常数(2.60～3.01)和较低的损耗角正切值(小于5×10-3),材料良好的介电性能源于介电性能优异的高纯度空心石英纤维增强相和较低密度的无碳氮化物基体。

Hollow silica fiber reinforced BN-Si3N4 matrix composites were fabricated by repeated infiltration and pyrolysis using a hybrid precursor containing borazine and perhydropolysilazane,and the effects of temperature on the densification behavior,mechanical properties,dielectric properties and microstructures of the composites were investigated.The results show that with the increase of the pyrolysis temperature from 300℃ to 500℃,the density of the composites increases,the elastic modulus increases accordingly,but the flexural strength shows a maximum value followed by an obvious decrease.The composite prepared at 400℃ exhibits a maximum flexural strength of 132.4MPa,which results from the good state of the silica fibers and controlled fiber/matrix interfacial microstructures.The dielectric constant also increases with the increase of temperature,but the dielectric properties of the composites prepared at three different temperatures are all good,with low dielectric constants of 2.60～3.01,and low loss angle tangent values below 5×10-3,which results from the high purity hollow silica fiber of the excellent dielectric properties and low density non-carbon nitride matrix.