Robert J. Locker

HOT VIBRATION DURABILITY OF CERAMIC PRECONVERTERS

The advent of thermally durable catalyst technologies has created the opportunity to move catalytic converters closer to the engine, providing a potential solution for cold start emissions. Close-coupled positioning exposes the converter to higher exhaust gas temperatures than experienced in underbody applications, permitting earlier catalyst light-off. The proximity of the converter to the engine will result in increased exposure to the vibrational energy created by combustion processes as well as intake and exhaust valve dynamics. This study investigated the thermo-mechanical challenges of mounting a ceramic substrate under severe conditions. In some instances ceramic substrates have been overlooked for application in the more demanding close-coupled environment. It will be shown that ceramic substrates mounted with standard intumescent mats survive under the most severe hot vibration testing conditions in the industry. Hot vibration testing is a very expensive activity. Therefore, testing a statistically significant sample population is not cost effective. Additional testing techniques were employed in this study to quantify hot vibration performance. These tests show promise in predicting hot vibration durability.