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 p repare alumina-based composites containing some kinds of dispersed pha ses. The composites were fabricated by reducing and sintering of Al2O3 /NiO/SiC mixtures. Reaction products (Ni3Si and C) and metallic Ni wer e found to disperse at the matrix grain boundaries, while Ni was partl y trapped into Al2O3 grains. In addition, carbon nanoballs encapsulati ng Ni3Si were produced and dispersed in the composites. The carbon cag es were approximately 80-100 nm in diameter with polyhedral shape, and had lattice spacing of 0.35 nm that was typical for the graphite. Enc apsulated Ni3Si had facet planes which were parallel to the carbon lay ers surrounding. Production of metal encapsulated carbon nanoball with in ceramic materials is the first successive result that might promote researches on such novel ceramic composites.