中文摘要：

以石英纤维预制件和硅溶胶为原料,采用溶胶-凝胶法制备了SiO2f/SiO2复合材料,在此基础上用尿素法制备了SiO2f/SiO2-BN复合材料,并对其力学性能和介电性能进行了测试。结果表明,随着工艺循环次数的不断增加,复合材料的密度随之提高,但增长速度逐渐减慢。三次循环后,SiO2f/SiO2-BN复合材料密度达1.81 g/cm3,弯曲强度和模量分别为113.9 MPa和36.5 GPa,分别比SiO2f/SiO2复合材料提高了12.1%和76.3%;纤维和基体界面结合良好,材料断面出现了明显的纤维拔出现象,为韧性断裂;复合材料介电常数和损耗角正切值分别为3.32和0.004,介电性能优良。

英文摘要：

Using fabric of silica fiber and silica sol as the raw materials,the silica fiber reinforced silica based composite materials（SiO2f/SiO2） were fabricated by the sol-gel method,and the silica fiber reinforced silica and boron nitride based composite materials（SiO2f/SiO2-BN） were prepared via the urea route.The mechanical properties and dielectric properties of the composites were investigated.The results show that the density of the composites increases with the increase of the cycles,while the densification becomes slow gradually.After three cycles,the density of the SiO2f/SiO2-BN composites reaches 1.81g/cm3.The flexural strength and elastic modulus are 113.9MPa and 36.5GPa,which increase by 12.1% and 76.3% compared with SiO2f/SiO2 composites,respectively.The interfacial combination between fiber and matrix is good and lots of fiber pull-out can be observed on the fracture surface,which suggests a good toughness.The composite has excellent dielectric properties with the dielectric constant and loss tangent being 3.32 and 0.004,respectively