Various causes for cyclic-loading fatigue in ceramics have been proposed. Degradation in the grain-bridging effect is the most important cause for cyclic-loading fatigue in nontransforming ceramics. Cyclic-and static-loading crack propagation behavior in terms of crack propagation rate, load-strain curve, and R-curve in compact tension specimens of polycrysalline aluminas with two types of average grain size is reported. Significant bridging is observed in coarse-grained alumina. The results are consistent with the proposal that grain bridging increases with grain size and that degradation in grain bridging is the most important cause for cyclic-loading fatigue in alumina ceramics.

Oxidation behavior of particulate matter (PM) in catalyzed diesel particulate filters (CDPFs) was investigated in the presence of ash through small-scale catalytic performance evaluation and visualization measurement. In the absence of ash, a CeO 2 -Ag CDPF reduces the PM oxidation temperature by approximately 100°C when compared with a CDPF with a Pt/Al 2 O 3 catalyst or a bare diesel particulate filter. The catalytic performance of the CeO 2 -Ag CDPF decreases in the presence of ash. However, this decrease is observed until the ash reaches 40 g/L in weight or 100 lm in thickness. An electron spin resonance analysis suggests that this remote PM oxidation is caused by the migration of superoxide species generated by the CeO 2 -Ag catalyst.

We studied flow-through type metallic Particulate Matter(PM) filter for diesel after treatment system. The structure could be verified advantage of soot oxidation due to tridimensional gas diffusion structure compared with wall-flow type PM filter. As a result, this metallic PM filter can be the simple vehicle application for soot reduction technology, and we got a improvement way of continuous re-generation system.

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