Thick thermal barrier coatings for diesel engines

The Caterpillar approach to applying thick thermal barrier coatings (TTBC) to diesel engine combustion chambers has been to use advanced modeling techniques to predict engine conditions and combine this information with fundamental property evaluation of TTBC systems to predict engine performance and TTBC stress states. Engine testing has been used to verify the predicted performance of the TTBC systems and to provide information on failure mechanisms. The objective of the Caterpillar program has been to advance the fundamental understanding of thick thermal barrier coating systems. Areas of TTBC technology examined in this program include powder characteristics and chemistry; bond coat composition; coating design, microstructure, and thickness effects on properties, durability, and reliability; and TTBC ''aging'' effects (microstructural and property changes) under simulated diesel engine operating conditions. Methods to evaluate the reliability and durability of TTBCs have been developed to understand the fundamental strength of TTBCs for particular stress states.