Porous SiC/SiCN composite ceramics fabricated by foaming and reaction sintering

Porous SiC/SiCN composite ceramics with heterogeneous pore structure and rod-like SiCN grains were fabricated by foaming and reaction sintering. The mixture slurry containing SiC and silicon as raw materials, cornstarch as binder, Y₂O₃ as sintering additive and an electrosteric dispersant was stirred with foams derived from pre-foaming using foaming agent. The casted green body was sintered at 1650 °C under nitrogen atmosphere. The results demonstrated that the porous SiC/SiCN ceramics exhibited hierarchical vias ranging from 1 μm to 1 mm and the rod-like crystalline SiCN grains generated in the SiC matrix.