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The high temperature creep data for radial specimens, cut from metal and ceramic substrates and subjected to compressive loads representative of mounting and thermal pressure are presented as function of load and temperature. These data show that the creep resistance of metallic specimens under sustained loading varies with temperature and is orders of magnitude lower than that of ceramic specimens. The observed creep deformation in metallic specimens reduces their open frontal area and hydraulic diameter with potentially adverse impact on pressure drop across the metallic substrate.

The dynamic fatigue data for two different cordierite ceramic wall-flow diesel filter compositions, EX-54 and EX-66, are obtained at 200° and 400°C using the 4-point bend test. These compositions offer larger mean pore size and experience lower pressure drop than the EX-47 composition, and hence are more desirable for certain applications. Their fatigue behavior in the operating temperature range is found to be equivalent or superior to that of EX-47 composition which helps promote filter durability. The fatigue data are used to arrive at a safe allowable stress, which would ensure the required 290K vehicle mile durability. The paper also discusses the impact of mean pore size on high temperature strength and fatigue properties and their effect on filter durability.