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The emissions regulations for the decade of 1990s are not only more stringent but are also required of vehicles other than passenger cars, for example both diesel and gasoline trucks as well as motorcycles. These latter applications involve different operating conditions in terms of space velocities, temperature profiles, and vibrational loads than those typical of passenger cars [1]*. In addition, the performance and durability requirements for these applications call for lower back pressure and longer service life. Furthermore, the space availability and the operating temperature range differ vastly so as to require special packaging designs to meet the durability requirements. This paper provides new data for ceramic insulating mats, both intumescent and non-intumescent [2,3], and ceramic substrates with thin and thick walls and square and triangular cell geometries [4], which are under development for non-passenger car applications indicated above.

The long term durability of a heavy duty gasoline truck converter is addressed by examining thermal stresses due to radial temperature gradients under three different driving schedules. The pertinent physical properties of a catalyzed cordierite ceramic converter, with triangular cell structure, are first measured as function of temperature. These are followed by thermal mapping of mid-bed temperatures with the aid of thermocouples under various driving cycles on the truck dynamometer. Both the physical properties and the temperature distribution are then used as input parameters in the finite element thermal stress model to compute stresses in the oval converter.