Preparation and characteristics of gelcast RBSC–B 4 C composite

The preparation and mechanical properties of silicon infiltrated SiC–B₄C composite were studied in the present work. Gelcasting process was adopted to obtain green bodies with uniformity and compaction. The gelation behaviour of the slurry was controlled by introducing the polymerisation inhibitor mixture and the gelation reaction was delayed to about 10 min with increasing B₄C content from 20 to 40%. Mechanical properties of the SiC–B₄C sintered samples were tested and the results showed that increasing B₄C content led to an increase in bending strength, fracture toughness and hardness. Microstructure investigation revealed that the SiC–B₄C composites showed less content of free silicon and finer grains comparing to RBSC ceramics.