Cross-scale construction of SiC-Si3N4 porous ceramics with superior electromagnetic wave absorption performance

A unique ceramic structure, which comprises whiskers in its pores and is capable of high-performance microwave absorption, has been designed by comnlining a sacrificial template method with catalytic nitriding. The influence of alpha-Si3N4 whisker content on the composition, structure, electromagnetic properties, and absorption properties of ceramics is also studied. The alpha-Si3N4 whisker content is controlled by changing the catalyst amount (FeCl2.4H2O). After adding 5 wt% FeCl2.4H2O, the highest alpha-Si3N4 whisker content is 78.06 %. The minimum reflection loss value of SiC-Si3N4 porous ceramics with thickness of 2.7 mm is-74.09 dB, rendering it superior than that of previously reported SiC-based absorbing ceramics. The supreior absorption performance is attributed to the reasonable structural design. The unique "whiskers in its pores" structure optimizes impedance matching, enhances attenuation loss and interference cancellation at three scales. This work provides new insights and ideas for the design and development of high-performance ceramic-based absorbing materials.