Structural evolution in reaction-bonded silicon carbide and boron carbide composites (RBSBC)

Reaction-bonded silicon carbide and boron carbide composites (RBSBC) are promising for laser mirror, armor and other applications. However, the structural evolution in RBSBC has not been fully understood. From microscopic characterization and thermodynamic analysis, we propose the mechanisms which can successfully explain observed microstructures, e.g., core-rim structure in SiC grains and plate-like SiC inside B4C grains, respectively. In addition, we find that the pre-existing SiC particles may hinder the formation of polygonal SiC in Si and lead to more B4C dissolution during the fabrication of RBSBC due to its lower B4C percentage than that in corresponding reaction-bonded boron carbide composites (RBBC). We believe that the results would shed light on potential fabrication optimization of RBSBC.