The behavior of ceramic thermal barrier coatings on diesel engine combustion zone components

Abstract

Abstract Partially stabilized zirconia ceramic thermal barrier coatings were plasma sprayed over an MCrAlY (M ≡ metal) bond coat on the valve faces and tulips, piston crowns and cylinder heads of two medium speed diesel engines to a specified total thickness of 0.015 in (0.4 mm). One engine was operated for 500 h on a test stand using a cyclic range of throttle settings that was representative of a locomotive engine's operation using number 2 diesel oil fuel. The other engine was operated in a towboat for 9000 h of service on the Inland Rivers, also using number 2 diesel oil fuel. Coating performance analyses were carried out on several parts after service. Coatings applied to piston crowns and cylinder heads generally performed in an acceptable manner. One type of coating on a valve face performed acceptably without coating loss or degradation. Two other types of coatings on valve faces failed for identifiable reasons. Overall, the durability of the coatings in a diesel engine combustion zone operating environment was promising.