Researchers at the Center for Thermal Spray Research (CTSR) at Stony Brook University presented a discussion about the application of thermal spray coatings designed to increase the efficiency of compression engines at the ITSC 2019 conference, sponsored by the Thermal Spray Society of ASM International.
The use of thermal barrier coatings 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 these benefits, TBCs have seen little implementation due to the lack of consensus in the literature regarding their efficacy.
Associated literature reveals a disconnect between the role of thermal transience, the necessary materials selection/processing controls, and the tuning of engine parameters for optimal performance. This is reflected in higher TBC surface temperature during intake, which causes heating of incoming gasses and reduces volumetric efficiency. Furthermore, uncontrolled coating surface topography dramatically changes combustion characteristics. These changes are manifested as increased smoke, particulate, and NOx emissions, particularly at high loads.
In this collaborative study between Stony Brook University and U. S. Army TARDEC, material and architecture variations were studied in relation to thermal response and toughness. A laboratory-designed thermal impulse test was used to simulate diesel engine transience and to rapidly screen promising coatings. This integrated approach allowed for down-selection of coatings and their subsequent application onto complex piston geometries, with the most promising candidates finally subjected to engine testing.
Title: Coatings for Increased Efficiency in Compression Ignition Engines
Authors: John Saputo, Hwasoo Lee, Gregory M. Smith, Prof. Sanjay Sampath, Center for Thermal Spray Research, Stony Brook University, New York.
