Porous SiCNnw/C/Si3N4 ceramics with controlled component and structure for electromagnetic wave absorption

Abstract

Ceramic–based electromagnetic wave (EMW) absorbing materials with lightweight characteristics and strong absorption properties can effectively reduce EMW pollution and interference. A simple technique for introducing wave–absorbing phases with multi–component and multi–microstructure in wave–transmitting ceramic matrices is essential for practical applications. Herein, porous SiCN_nw/C/Si₃N₄ ceramics comprising a two–component absorbing phase with a heterogeneous interface and nanowire structure have been prepared via simple vacuum impregnation and heat treatment. Porous Si₃N₄ ceramics with low permittivity are used as the impedance matching matrix, while carbon layer and SiCN nanowires are used as wave loss phases. The heterogeneous interface between the carbon layer and Si₃N₄ and the nanowire structure of SiCN can enhance the polarization relaxation behavior and electron transport capacity in the material. The conversion of carbon into SiCN nanowires can be promoted by elevating the heat treatment temperature, which can effectively regulate the ratio of the two wave–absorbing phases, thus optimizing the impedance matching and realizing efficient EMW absorption. The prepared C1400/20 sample has a minimum reflection loss of −61.24 dB at a thickness of 2.77 mm and an effective absorption bandwidth (EAB) of 6.30 GHz at a thickness of 2.63 mm. The C1400/25 realizes an EAB of 5.61 GHz at a smaller thickness of 2.09 mm. Overall, this study provides new ideas for designing ceramic–based materials with excellent EMW absorption performance.