Coatings for Increased Efficiency in Compression Ignition Engines – Coating Development, Open Issues, and Performance Updates

Coatings for Increased Efficiency in Compression Ignition Engines – Coating Development, Open Issues, and Performance Updates John Saputo, Carl Schmidt, Sanjay Sampath – Center for Thermal Spray Research Eric Gingrich, Michael Tess – US Army CCDC-GVSC The use of thermal barrier coatings (TBCs) in reciprocating engines has been pursued for more than 40 years. While their introduction can be traced to reducing cooling in military vehicles, contemporary research focuses on improving fuel economy, reducing emissions, and enabling alternative fuels. Despite potential theoretical benefits TBCs have seen little implementation due to the lack of consensus taken in the literature regarding their efficacy. Coating developments previously reported from this collaborative study between Stony Brook University and the US Army CCDC-GVSC have revealed improvements to indicated thermal efficiency without significant emission penalties in select cases. However, attempts to optimize materials have led to many questions centered around the role of surface characteristics, open pores, sensitivity to thermal properties, and impact of the coating on heat transfer. These issues have been strategically probed through the fabrication of thermal barriers tailored to each scenario on complex piston bowl geometries, with detailed process information, material properties, and single cylinder engine test results described herein.