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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 high temperature strength and deformation behavior of ceramic and two different metal substrates were measured in the 25°-1200°C temperature range in uniaxial and biaxial bending using rectangular bars and circular discs, respectively, prepared from the substrates. The data show that both of the metal substrates exhibit permanent deformation and lose their load carrying capability by an order of magnitude above 800°C. The ceramic substrate, on the other hand, preserves its strength and behaves elastically over the entire temperature range exhibiting neither permanent deformation nor cell distortion. These data suggest that the upper use temperature for metal substrates could be significantly lower than that for ceramic substrates to meet 50-100K vehicle mile durability