Corrosion of Refractory Materials by Liquid Slags Formed from the Combustion of Straw

Abstract The oxidative deterioration of three refractory metals at 1100–1150°C in the presence of liquid slag formed in the combustion of straw is presented, with emphasis on the reactions which occur at the metal/slag/gas interface. Thick coatings of slag decreased the rate of oxidation. However, there was evidence that a volatile component of the slags increased the rate of oxidation of unprotected surfaces. Quantitative scanning electron microscopy provided an estimate of the extent of reaction. Of the metals investigated, (304s.s., 316s.s., Inconel 600) Inconel 600 provided the best corrosion resistance. However, for each alloy, chromium was found to be depleted at the metal/gas interface, being concentrated as an oxide corrosion product. Calculated diffusion coefficients for Cr were close to values reported in the literature.