Optimal design and preparation of silicon nitride ceramic radome material with gradient porous structure

In this study, a gradient porous Si3N4 ceramic radome wall structure is promoted for broadband (1?18 GHz) application. By optimising the thickness and dielectric constant, the transmission efficiency at 1?18 GHz is calculated based on the microwave equivalent network method. Si3N4 ceramics with gradient porous structure are then prepared. Si3N4 ceramics of controlled relative density ranging 53?99% and dielectric constant ranging 3?8 are prepared by adding different additives such as ZrP2O7, MgO and Al2O3, using pressureless sintering and spark plasma sintering. The results show that Si3N4 ceramics is still α phase and exhibit a good gradient porous structure.