In order to develop chrome-free refractory materials applicable in coal
slurry gasification, SiC-CaAl12O19 (SiC-CA6) composite refractories were
developed and prepared by using SiC aggregates and CA6 powders as main raw
materials. The sintering behaviour of the composites was investigated. After
firing at different temperatures under CO atmosphere, the effects of
oxidation of SiC aggregates on the sintering behaviour and microstructures
of SiC-CA6 composite refractorieswere investigated. SiC-CA6 composites could
not be sintered when firing temperature was lower than 1500?C. SiC had a
passive oxidation and the oxidation components were able to react with CA6
to form CaAl2Si2O8. The CaAl2Si2O8 melted into liquid when sintering
temperature was in the range of 1500-1600?C, which promoted the sintering
process of the SiC-CA6 composites. At temperatures above 1600 ?C, an active
oxidation of SiC occurred. Simultaneously, SiC could also reacted with the
SiO2(s,l) to form SiO, leading to the precipitation of Al2O3 and CaO in the
liquid to generate plate-like CA6. Above this temperature, the sintering of
the SiC-CA6 composite refractories was affected by the growth of CA6 and
oxidation of SiC. This work demonstrates that the optimal sintering
temperature for the SiC-CA6 composite refractories was 1600?C.
Effects of oxidation of SiC aggregates on the sintering behaviour and microstructures of SiC-CaAl12O19 composite refractories