Diamond reinforced reaction-bonded boron carbide composites: Fabrication, microstructure, mechanical and tribological properties

Reaction-bonded boron carbide composites were fabricated by molten silicon infiltration of diamond-containing boron carbide preforms. The effects of diamond particle size on the microstructure, mechanical and tribological properties of reaction-bonded boron carbide composites were investigated. Fine diamond particles (<= 7.7 mu m) completely reacted with silicon generating nano silicon carbide particles, which bonded the boron carbide particles forming a 3-D ceramic skeleton and improving the flexural strength of the composites. Coarser diamond (>= 24 mu m) particles were retained protected by a dense SiC layer generated from the reaction of diamond and molten silicon. A "core-shell" structure with the retained diamond as the "core" and with the reaction formed silicon carbide as the "shell" formed. Relief structures were established on the composites' surface during the wear process, greatly reducing the friction coefficient and improving the wear resistance.