Pressureless sintering and properties of αSiC–B4C composite

Pressureless sintering process to obtain high density silicon carbide–boron carbide (5% vol) composite (BCSiC) was studied. Sintering behaviour of this material was investigated between 1950 and 2200°C and it was compared to SiC material doped with boron and carbon. Density up to 96% T.D. was reached at 2150°C. Microstructural investigation revealed that B4C grains, having an average size of 2 μm, were well dispersed in the SiC matrix. Mechanical properties like fracture toughness, hardness, flexural strength were determined in the range RT-1500°C and compared to other SiC-based material. BCSiC material showed same fracture toughness of SSiC, higher hardness and higher flexural strength than SSiC also at high temperature; these properties make BCSiC a very interesting material for application in which high oxidation resistance is requested, e.g. ceramic heat exchanger.