Microwave attenuation performance of Mg₂SiO₄-SiC materials by pressureless sintering

Mg₂SiO₄-SiC composite materials were prepared by pressureless sintering at 1450°C for 1 h under H₂ atmosphere using Mg₂SiO₄, SiC as raw materials and Al₂O₃-BaO-SiO₂ as composite sintering additives. The phase composition and microstructure of composite materials were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM). The effects of SiC addition on the microwave characteristics in X band (8-12 GHz) were investigated. The results show that a certain amount of Al₂O₃-BaO-SiO₂ composite sintering additives are effective in promoting densification, the apparent porosity of composite materials is below 0.5%. As the SiC content increased from 0 to 10%, the harmonic frequency decreases from 11.8 GHz to 10.0 GHz, at the same time, absolute value of the attenuation peak decreases from 3.62 dB to 1.18 dB and effective attenuation bandwidth increases from 0.48 GHz to 1.03 GHz. The harmonic frequency of composites shifts to a low frequency attenuation peak, the effective attenuation bandwidth increases.