Catalytic converters, ceramic honeycombs substrates

Reduced thermal mass came from changes to the catalyst support. The catalyst materials are deployed as a thin coating on a ceramic honeycomb substrate. The surface area for the deployment of the catalytic coating, and the mass of the substrate both contribute to the overall performance of the catalytic converter. The surface area was increased by reducing the thickness of the channel walls, thereby increasing the flow channel density and reducing the thermal mass of the substrate. 

The microstructure of ceramic honeycombs not only affects physical properties like CTE, strength, and structural modulus, but has a strong bearing on substrate/washcoat interaction, which, in turn, affects the performance and durability of the catalytic converter [28-30]. The coefficient of thermal expansion, strength, fatigue, and structural modulus of the honeycomb substrate (which also depend on cell orientation and temperature) have a direct impact on its mechanical and thermal durability [22). Finally, since all of the physical properties are affected by washcoat formulation, washcoat loading, and washcoat processing, they must be evaluated before and after the application of washcoat to assess converter durability [28-30]. 

FIGURE 37.10 Looking through two ceramic extruded cordierite honeycomb substrates for catalytic converters. 

---