Towards chrome-free of high-temperature solid waste gasifier through in-situ SiC whisker enhanced silica sol bonded SiC castable

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Refractory containing Cr2O3 was widely used in solid waste gasifier due to its excellent slag resistance. However, hexavalent chrome compounds (formed during the preparation and the use of refractory containing Cr2O3) will give rise to detrimental effect on environment and human's health. In addition, the Al2O3-Cr2O3 materials acted as the lining materials. Serious exfoliation occurred after about twenty days. For the purpose of chrome-free and service longevity of lining materials for solid waste gasifier, in-situ SiC whisker enhanced SiC castable and spinel castable containing 20%wt of Cr2O3 were prepared. The mechanical properties and corrosion resistance after heat treatment in different temperature of the castables were determined. The strength of SiC castable rised with the increasing of the temperature. And the nano SiC/SiO2 core-shell whiskers was formed at 1500°C. In comparison to the spinel castable containing 20wt% of Cr2O3, the better volume stability and the reinforcement of the nano whiskers led to excellent resistance to crack propagation at high temperature. In addition, SiC castable showed lower apparent porosity because of the forming of SiO2 through the oxidation of SiC over 1300°C, the viscosity of slag increased since that the SiO2 dissolve into the slag, which caused excellent penetration resistance of SiC castable compared with spinel-Cr2O3 castable. Excellent mechanical properties and slag resistance at high temperature indicated that SiC castable had the application prospect for high-temperature solid waste gasifier.