Preparation of hollow SiC spheres with biological template and research on its wave absorption properties

In this work, SiO2 was evenly coated on dry yeast as biological template by sol-gel method, and the internal substances of yeast were removed at 700 degrees C to obtain hollow silicon template. Then, RF aerogel (carbon source) was used to wrap the silicon template. After carbonization treatment, carbon thermal reduction reaction was carried out at 1400 degrees C to obtain hollow SiC spheres (HSS). Under the coating of RF aerogel, the hollow SiO2 maintained its complete physical shape in the process of high-temperature synthesis, and the final product was hollow ellipsoidal silicon carbide with the maximum diameter of about 4.3 mu m and the minimum diameter of about 3.5 mu m, basically keeping the shape of yeast. The basic properties of the products were characterized by XRD, FT-IR, SEM, TEM and Tg, the absorption properties of the products were analyzed by VNA. The research found that the absorption performance of the hollow SiC with yeast morphology increased significantly in the frequency band of 2-18 GHz. When the thickness is 3.1 mm, the hollow SiC has the maximum reflection loss of -51.74 dB at 12.08 GHz. When the thickness is 4.0 mm, it has an effective absorption frequency width of 6.05 GHz, which has obvious advantages over SiC without special hollow morphology. The effect of hollow structure on the electromagnetic properties of SiC is discussed in detail. (C) 2019 Elsevier B.V. All rights reserved.