High throughput synthesis of SiO2 microspheres enhancing dielectric properties of quartz fibers insulation composites for high temperature resistant communication cable

The development of the digital society has led to an urgent demand for high-temperature-resistant, low-dielectric cable insulation materials. In order to meet the stable high temperature service performance, it is necessary to use inorganic materials instead of the traditional organic insulating materials as the cable insulation layer. Silicon dioxide (SiO2) as a widely used inorganic dielectric material has great potential for application, and quartz fiber is another wave-transparent material with good dielectric properties. The combination of SiO2 and quartz fiber can provide a feasible path for pure inorganic composite insulation materials. In this work, the high-throughput (>50 g) synthesis of SiO2 was investigated to explore the factors affecting the dielectric properties. The effects of different quartz fiber composite amounts and sintering temperatures on the dielectric properties of the composites were investigated by testing the dielectric properties of the composite powders after pressing. The composite powders doped with 20wt% quartz fibers at 600 °C sintering temperature were found to have better dielectric properties with dielectric constant of 2.48 and dielectric loss of 0.0109 at 20 M Hz. Furthermore, the composite powders were filled into the cables and measured for electrical properties by a network analyzer. And dielectric properties of the cables preliminarily meet the performance requirements for the applications of high temperature (900 °C) radio frequency (RF) communication cables with dielectric constant of 1.731 and insertion loss of 2.02 dB at 18 G Hz. Therefore, this inorganic composite material can be used as the insulation layer for RF high-temperature-resistant communication cables for aerospace, nuclear power plants and energy fields.