Oxidation behavior of sintered tubular silicon carbide in pure steam I: Experiments

Abstract

Experimental investigations are conducted on sintered tubular SiC in oxidizing environments containing pure steam at 1 atm with temperature range of 1140-1500 degrees C and velocity between 0.8 and 10 m/s. Linear weight loss was observed with time. The linear weight loss rates exhibit sensitive dependence on flow rate at a given temperature, demonstrating effects of flow boundary-layer diffusion rate on silica volatilization kinetics. Silica scale exhibits morphology change with respect to exposure time in an oxidizing environment, progressively demonstrating bubble formation and surface smoothing, extensive formation of cracks and pores, and crack reduction. Yet, strength measurements of pressure-less sintered SiC show no significant change after oxidation in the tested conditions. Hence, the primary life-time limiting factor for structural application of pressure-less sintered SiC in the tested environments is anticipated to be the loss of the material.