Chemical and physical stability of refractories for use in coal gasification. Fourteenth quarterly progress report, August 1, 1979-October 31, 1979

This paper described the corrosion resistance of refractories, especially the bond phases, in high pressure/high temperature gases and liquids present in coal gasification environments. The results of completed exposures are given. Comparison of liquid versus vapor exposure, for the DOE atmosphere, in terms of MOR, for various castables is given. As previously observed for castables exposed to pure steam, all the dense alumina castables had a higher strength after exposure to either the saturated vapor or immersed in liquid, compared with their controls (fired at 5000/sup 0/F in air for 18 h). The large increase in MOR is attributed to the formation of additional bonding phases, such as boehmite and calcite. With the exception of UMR-8, which showed a higher flexural strength for immersed specimens, all the castables immersed in liquid or exposed to saturated vapor had similar MOR's. Comparison of the flexural strength of dense castables on the basis of the cements and aggregate they contain show that castables containing CA-25 cement (UMR-1 and UMR-8) had a generally higher strength than those containing refcon (UMR-4 and UMR-5). On the other hand, the aggregates (tabular alumina versus calcined kaolin) seem to have no significant effect on the flexural strength ofmore » dense castables. Samples made with the same cement, but different aggregates had close to the same MOR. The insulating castables, generally, showed no large change in MOR after exposure to the DOE atmosphere at 1000 psia. The same results were found in the previous tests in the previous tests in pure steam at 410 and 1000 psia.« less