High temperature behavior of pressureless-sintered SiC in a steel soaking pit environment

Sintered-..cap alpha.. SiC was exposed for about 800 h at about 1250/sup 0/C to a steel soaking pit environment. A slag layer consisting of hematite and low cristobalite in an Fe-K-Ca silicate glass matrix was formed on the external surface of sintered-..cap alpha.. SiC. No measurable corrosion or loss of material was observed. Large angular pores and depletion of graphite sintering aid, observed in the surface region of the as-received material, resulted in a lower-than-usual fracture strength. The fracture strength increased slightly following the exposure. Auger electron spectroscopic analysis identified oxygen penetration in the near-surface region of the exposed material. The results suggested that sintered-..cap alpha.. SiC would be suitable for use as a heat exchanger material in steel soaking pits. 8 references, 8 figures, 1 table.