No abstract

The thermal shock fatigue resistance of cordierite and SiC filters with a mullite filtration layer was evaluated under simulated reverse cleaning conditions. O‐ring specimens were thermally shocked by cyclically blowing cold air outward through them while they were exposed to high‐temperature flue gas. The calculated values of the tangential tensile stresses induced by the temperature differences between the inner and outer surfaces were found to be largest at the inner surfaces. It was also found that the elastic modulus and the thermal expansion coefficient of the filters affect the magnitude of the thermal stresses more than the thermal diffusivity and thermal transfer area, which were directly related to the microstructure of the filters. Failure of both filters is believed to have initiated at the inner subsurfaces because of the effects of thermal shock. The thermal shock fatigue lifetimes increased as thermal stresses decreased. The fatigue parameters for the SiC and cordierite filters were found to be 41 and 22, respectively. These parameters probably vary over different operating temperature ranges, especially in the case of SiC filters, where changes in their composite microstructures affect their high‐temperature strength.

No abstract

No abstract