Abstract

Abstract: SiC refractories are currently utilized as lining material for water-cooled gasifier at a service temperature lower than 1300oC. Very few researches have been reported on the corrosion of SiC materials at even higher temperature. Furthermore, the standard test method for rotary slag testing of refractory materials can not simulate the real gasification atmosphere, which may lead to inaccuracy of evaluation results. In this paper, corrosion behavior of SSiC and Si3N4-SiC refractories by coal slag was investigated at 1500oC under reducing atmosphere using improved rotary slag testing method. Moreover, interactions between refractory materials and molten slag were also predicted by thermodynamic calculations using modified model under the same conditions. The results showed that SSiC and Si3N4-SiC refractories presented the similar stability and corrosion behavior under simulated gasification conditions. The porous materials showed small amounts of slag infiltration but obvious oxidation reactions. SiC reacted with FeO to form Si-Fe-C alloy on the surface of the corroded materials. Meanwhile, SiO2 phase was also formed by oxidation of SiC in the experimental atmosphere and then dissolved into molten slag eventually. The thermodynamic calculation results matched well to the experimental observations.

Key words: SiC refractories; Improved rotary slag testing method; Thermodynamic calculations; Oxidation

Corresponding author's email: andyzhaosx@163.com(S. Zhao)