Hot-corrosion behavior of silicon nitride-bonded silicon carbide

In this work, the hot-corrosion behavior of silicon nitride-bonded silicon carbide composite(SCN) in aluminum melt are studied especially on the simil ar environment to the actual working condition. The thermal shock resistanc e and cyclic thermal shock behavior of this composite are also studied. Pre -oxidized specimens corroded more extensively than as-cut specimens in Al m elt at the same temperature. The specimens, which were pre-oxidized and imm ersed in Al melt, showed a severe reduction in their mean compressive stren gth. The mass changes of SCN oxidized at 850 degreesC-1200 degreesC followe d parabolic kinetics but pore neck blocking happened at 1200 degreesC, The activation energy was found to be 223 kJ/mol. In water quenching test of SC N composite, the critical thermal shock temperature difference was about 42 5 degreesC. The repeated thermal stress by the cyclic heating and cooling c aused the decrease in strength.