Corrosion Behavior and Mechanical Properties of Silicon Carbide Exposed to a Coal Gasification Environment

摘要

Silicon carbide ceramic materials have been shown to have exceptional properties for many engineering applications. In the case of coal gasification systems, potential applications such as high-temperature heat exchangers must withstand a very hostile environment. This study included an evaluation of the effects of a coal gasification environment on the physical and mechanical properties of a silicon carbide ceramic. The corrosion behavior of specimens exposed in the absence or presence of a coal slag coating, and subsequent changes in mechanical properties, were evaluated. It was found that very little change in the specimens occurred after 200-h exposures at temperatures ranging from 1000 to 1300 exp 0 C, when coal slag was not applied. Samples exposed with a coal slag coating exhibited no change after exposure at the lowest temperature, 1000 exp 0 C. However, samples exposed at 1250 and 1300 exp 0 C, with a slag coating, exhibited weight loss and some degradation of mechanical properties due to slag/silicon carbide interactions. Evidence of the formation of a protective silica scale between the slag and the silicon carbide suggests that the corrosion reactions may be inhibited after an initial reaction period. 21 refs., 21 figs., 10 tabs. (ERA citation 10:038622)