Molten salt synthesis and characterization of SiC whiskers containing coating on graphite for application in Al2O3-SiC-C castables

Abstract

The wettability of graphite was significantly ameliorated by applying a molten liquid phase method using silicon powder as a raw material to form a SiC whisker coating on a graphite surface. The effect of replacing the ball pitch with coated graphite (CG) on the microstructure, apparent porosity, physical properties, oxidation resistance, and slag corrosion resistance of Al2O3–SiC–C (ASC) refractory castables was investigated by a scanning electron microscope, an energy-dispersive X-ray spectroscope, a transmission electron microscope, and other dedicated equipment. The results show that a uniform and continuous SiC whisker coating was formed on the surface of the graphite, and the contact angle with water changed from 89° to only 6.5°. The apparent porosity of the ASC specimen with 2 wt.% of CG decreased by 12.7%, and the cold modulus of rupture increased from 7.08 to 13.30 MPa with increasing CG content from 0 to 2 wt.%. Further, the sample containing 2 wt.% of CG exhibited the largest force and displacement values. Owing to the presence of SiC whiskers on the surface, the ASC castable samples with 2 wt.% of CG have the best antioxidation performance, and those with 1 wt.% of CG have the best anti-slag performance.