High-temperature resistant, low dielectric SiO2@Quartz fiber composites for high fidelity communication cables

High-fidelity communication in extreme environments has attracted significant attention due to its potential applications in aerospace, polar, deep-sea exploration, fire rescue, and nuclear industries. Yet, challenges persist in constructing dielectric layers with both low dielectric constant and high-temperature stability in communication cables. Herein, low-dielectric inorganic composites utilizing pure silicon oxide (SiO2) are employed as a substitute for conventional organic materials or their composites. By incorporating the in-situ growth of SiO2 microspheres (m-SiO2) on the quartz fiber structure, the composites exhibit a reduced dielectric constant while improving mechanical performance. The flexural stress of the m-SiO2@quartz fiber composites is twice as high as that of the composites prepared by the ex-situ synthesis method. Furthermore, the m-SiO2@quartz fiber composites display high-temperature resistance up to 800°C with a mass loss less than 1%. With 30 wt% of quartz fibers, 20 nm of m-SiO2, and 6 wt% of the foaming agent, the composites exhibit a dielectric constant of 1.95. Based on the low-dielectric m-SiO2@quartz fiber composites, the cable demonstrates a voltage standing wave ratio (VSWR) of 1.46, an attenuation of 1.22 dB, and a characteristic impedance of 48 Ω.