Nickel-catalyzed preparation of self-bonded SiC refractories with improved microstructure and properties

Abstract 3C-SiC was synthesized after 3 h firing of Si and expanded graphite in flowing Ar at 1300 °C with in-situ formed Ni nanoparticle (NP) catalyst. First-principles calculations suggest that Ni catalyst accelerated the formation of SiC via weakening the bonds in adsorbed C C bond, and CO and SiO molecules. Apart from this, Ni NP catalyst facilitated the epitaxial growth of SiC nanowires. Based on these findings, self-bonded SiC refractories were prepared by using black SiC grain, expanded graphite and Si powders as raw materials and Ni NP as a catalyst. Large amounts of SiC nanowires were catalytically formed in the fired refractories specimens, which resulted in significant improvements in both mechanical strength (MOR of 32.2 MPa at 1400 °C) and thermal shock resistance. The catalytic formation method investigated in this work could be readily modified and extended to develop many other types of high performance refractories.