Microstructural characteristics of alumina-based composite prepared by in situ reaction of alumina-silicon carbide-nickel system

In situ reaction of nickel and silicon carbide has been attempted to prepare alumina-based composites containing some kinds of dispersed phases. The composites were fabricated by reducing and sintering of Al₂O₃/NiO/SiC mixtures. Reaction products (Ni₃Si and C) and metallic Ni were found to disperse at the matrix grain boundaries, while Ni was partly trapped into A1₂O₃ grains. In addition, carbon nanoballs encapsulating Ni₃Si were produced and dispersed in the composites. The carbon cages were approximately 80-100 nm in diameter with polyhedral shape, and had lattice spacing of 0.35 nm that was typical for the graphite. Encapsulated Ni₃Si had facet planes which were parallel to the carbon layers surrounding. Production of metal encapsulated carbon nanoball within ceramic materials is the first successive result that might promote researches on such novel ceramic composites.