【摘要】 分析了低温预氧化过程对聚碳硅烷(PCS)先驱体结构的影响,研究了不同预氧化温度和时间下SiCf/SiC复合材料室温和高温介电性能的演变规律。结果表明:经预氧化处理后基体中的氧含量增加,生成具有低介电常数的Si CxOy相,且其含量随着预氧化温度的升高或时间的延长逐渐增加,SiC微晶和自由碳的含量均减少,因此SiCf/SiC复合材料的复介电常数明显降低,同时高温复介电常数的升高幅度显著减小。经260℃-6 h预氧化处理后,700℃时复合材料在整个X波段的反射率均达到-8 d B以下,高温吸波性能得到有效改善。更多还原

【Abstract】 In the present work,the effects of low-temperature pre-oxidation process on the structures of PCS precursor were analyzed,and the evolutions of room-and high-temperature dielectric properties of SiCf/SiC composites at various pre-oxidation temperatures or time were investigated. Results indicate that oxygen content increases in the matrix and SiCxOyphases with low complex permittivity are generated after low-temperature pre-oxidation process. SiCxOycontent increases with the increase of pre-oxidation temperatures and time,while both the contents of SiC phase and free carbon decrease,which significantly results in the reduction of complex permittivity of SiCf/SiC composites. In addition,the increasing range of high-temperature complex permittivity is also reduced. After pre-oxidized under 260 ℃-6 h,the reflection loss of composites at 700 ℃ can be inferior to-8 d B in the whole X band,which indicates that the high-temperature microwave absorbing properties are effectively optimized.更多还原