Si3N4 based ceramics such as hot isostatically pressed Si3N4, hot pressed Si3N4, hot pressed sialons containing 0, 30, 60 and 100% of α phase were corroded by V2O5 melts at 700 to 1000‡C. These Si3N4-based ceramics were oxidized to SiO2 and dissolved into V2O5 melts. The surface chemical reaction controlled shrinking core model adequately described the relationship between the weight loss of the specimen and time for the corrosion reactions in V2O5 melts, and the apparent activation energies were 69 to 112kJ mor-1. Β phase Si3N4 and sialon showed higher corrosion resistance than α phase sialons, but no clear relationship between the corrosion rate and the content of additives was found. The specimens corroded by V2O5 melts showed no significant degradation in the fracture strength up to 30wt% of weight loss.
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