Mechanical performance and oxidation resistance of SiC castables with lamellar Ti3SiC2 coatings on SiC aggregates prepared by SPS

SiC castables face serious degradation under a 1700 degrees C oxidation atmosphere in plasma gasifier. We used spark plasma sintering (SPS) and added Ti/Zr combined with Si and carbon black to improve the mechanical performance and antioxidation of the SiC castable. Metal Ti and Si formed liquid drops at high temperature and carbon black dissolved into the drops to form Ti-Si-C drops. Based on the principle of electrowetting, the wetting of the SiC aggregate by the Ti-Si-C drop was improved significantly under a high-frequency pulse electric field in the SPS system. The Ti-Si-C drop coated the SiC aggregate and formed Ti3SiC2, which resulted in the SiC aggregates being coated by in-situ lamellar Ti3SiC2. The new binder phase significantly improved the mechanical properties and the lamellar Ti3SiC2 coating was preferentially oxidized to TiO2 and SiO2. The TiO2 pinned SiO2 glass, which formed a protective layer on the SiC aggregate surface against further oxidation. (C) 2019 Elsevier B.V. All rights reserved.