Preparation and strength of SiC refractories with in situ β-SiC whiskers as bonding phase

SiC refractories with in situ SiC whiskers as the bonding phase were produced by carbonization at 1500 degrees C. The effects of atmospheric heat treatment and the Si content on the hot strength of the SiC refractories were studied. The pressed samples were cured at 180 degrees C for 8 h and fired at 1500 degrees C for 6 h in coke, anthracite, or a graphite bed. Characterization of the samples by X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy showed that the beta-SiC whiskers were formed in situ through the vapor solid mechanism. The interfacial bonding was strengthened by the interconnected structure. The coke or anthracite, whose reactivity is higher than that of graphite, accelerated the formation of thick beta-sic whiskers. The hot strength was improved by up to 59.33 MPa at 1400 degrees C in the sample containing 16 wt% silicon. (C) 2015 Elsevier Ltd and Techna Group S.r.l. All rights reserved.