Abstract
Herein, porous Si_3N_4 ceramics embracing excellent mechanical and dielectric properties were achieved via gelcasting using N, N-dimethylacrylamide (DMAA) gel system while acting as pore-former. The increase of monomer content (8.0-23.0 wt%) led to an increase in porosity (39.53-43.60%) and pore connectivity, which accelerated vapor phase mass transport and promoted p-Si_3N_4 grain growth, thereby improving flexural strength (212.33-245.30 MPa) and fracture toughness (3.60-3.89 MPa-m~(1/2)). Attributable to the pores introduced by increasing monomer content, the e' and tanδ were significantly reduced with the values of 4.18-4.29 to 3.95-4.06 and 1.83-2.38 × 10~(-3) to 0.37-1.96 × 10~(-3), respectively, demonstrating excellent microwave-transparent properties. This work proved the great application potential of porous Si_3N_4 ceramics fabricated by gelcasting employing DMAA gel system in the field of microwave-transparent materials.
NSTL
Elsevier