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U.S. Department of Energy
Office of Scientific and Technical Information

Durability of ceramic coatings in 14,000 hours service in a marine diesel engine

Conference ·
OSTI ID:5330384
A representative selection of diesel engine combustion zone components coated with plasma sprayed zirconia thermal barrier systems was analyzed after 14,000 hours of practical engine service. The analysis consisted of determining the degree of success of the different coating systems and suggesting probable mechanisms of failure. The coating systems under investigation include a flame stabilized and a pre-alloyed 8% Y/sub 2/O/sub 3/-ZrO/sub 2/, and a flame stabilized 22% MgO-ZrO/sub 2/. All three of these systems applied to piston crowns survived engine service with no noticeable deterioration of any kind. Coating performance on valve faces was mixed. The 22% MgO-ZrO/sub 2/ valve coating consistently spalled at or near the interface with the bond coat. This failure was due to the volume expansion associated with the observed phase transformation of the zirconia to the monoclinic structure. The flame stabilized 8% Y/sub 2/O/sub 3/-ZrO/sub 2/ on the valves consistently failed over large regions while the pre-alloyed coating of the same composition survived with only minimal loss. The performance pattern of all three systems after 14,000 hours closely resembled their performance determined during a similar study at the conclusion of 9000 hours engine service. This strongly suggests that the successful coating system-engine component combinations indicated have the durability to reliably serve through the overhaul lifetime in this type of service (18,000 to 22,000 hours).
OSTI ID:
5330384
Report Number(s):
CONF-880104-
Country of Publication:
United States
Language:
English