Research on Oxidation Resistance of Silicon Carbide Refractories to High Temperature Steam

Abstract

Refractory linings of waste incineration plants based on oxidation resistant SiC materials enable a long service life at suitable firing and operation conditions. Steam oxidation resistance of Si3N4-SiC, SiO2-SiC, SiAlON-SiC material at 1000°C was tested according to ASTM-C863 after 50c, 100h, 200h, 250h and300h respectively. The phase composition and microstructure before and after oxidation were analyzed by means of XRD and SEM. Results indicate that there is continuous increase of volume expansion and weight change on materials with the oxidation to the oxidation time. After 50h of oxidation, a small amount of cristobalite can be observed in these materials, which comes directly from the oxidation of SiC, Si2N2O and SiAlON or from the crystallization of glass phase. Oxidation weight gain occurs in the first 50 h, but volume expansion takes place after 50h . Compared with the three materials, SiO2-SiC material has a smaller weight change and volume expansion. Comparing the SEM these three materials, it is obvious that SiO2-SiC material has a better density after 300h. Based on the above results, conclusions can be reached that: the sample of SiO2-SiC has better oxidation resistance and is more suitable as lining material of waste incinerator.