Effects of different catalysts on performance of self-bonded SiC refractories

Abstract

The 3C–SiC whisker was catalytically synthesized with extended graphite and Si powder firing at 1573K using 1 wt% Fe, 3 wt% Co or 3 wt% Ni as catalysts, respectively. First-principles calculation results show the activities of the reactants of the synthesis of SiC could be increased via dwindling the bonding strength of CC, Si–O and C–O bonds. Furthermore, the performance of self-bonded SiC refractories prepared by the present catalytic method was enhanced including the mechanical properties (Fracture toughness of 1.35 MPa﹒m1/2 for the containing Fe catalysts samples, Fracture surface energy of 114 J﹒m−2 and MOR of 32.2 MPa (1473 K) for the sample with Ni catalysts), as well as the TSR (Residual MOR and Residual MOR percentage of 13.17 MPa and 62% at ΔT = 1075 K, respectively). The results indicate that the incorporation of catalysts decreased the reaction temperature by about 100 K as well as facilitated the in-situ formation of 3C–SiC whiskers, which interlinked and connected each other in the matrix of as-prepared self-bonded refractories and improved the high temperature properties. Among them, the Fe NPs presented the best catalytic activity.