Thermal Swing Evaluation of Thermal Barrier Coatings for Diesel Engines
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Thermal Swing Evaluation of Thermal Barrier Coatings for Diesel Engines John C. Saputo1 • Gregory M. Smith1,2 • Hwasoo Lee1 • Sanjay Sampath1 Eric Gingrich3 • Michael Tess3
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Submitted: 24 May 2020 / in revised form: 14 October 2020 / Accepted: 18 October 2020 Ó ASM International 2020
Abstract ‘‘Thermal swing’’ coatings have recently been of great interest to automotive researchers for their potential to insulate internal combustion engines, reduce cooling requirements, and increase their efficiency. Plasma-sprayed yttria-stabilized zirconia, ceramics in the MgO-Al2O3-SiO2 system (cordierite, mullite, and steatite), and silicate-yttriastabilized zirconia composite thermal barriers have been investigated in this context with thermophysical properties measured using a thermal flash method and further screened by thermal swing using a custom laboratory developed functional test. Correlations between microstructure and thermal properties are developed and their combined impact on thermal swing assessed. The coatings thermal effusivity dominates these considerations for coatings above the characteristic thermal diffusion length of periodic exposure, with substrate thermal properties quickly becoming important below this thickness. Plasma-sprayed cordierite and its composites are determined to be the most promising materials for this application, exhibiting the highest thermal swing and effusivities as low as 373 Ws1/2/m2K. Performance testing in a heavy-duty single-cylinder diesel engine is ongoing with preliminary data suggesting that thermal swing alone may not provide efficiency benefits. Coating thickness,
& John C. Saputo [email protected] 1
Center for Thermal Spray Research, 130 Heavy Engineering Bldg., Stony Brook University, Stony Brook, NY 11794-2275, USA
2
Naval Research Laboratory, 4555 Overlook Ave SW, Washington, DC 20375, USA
3
U.S. Army Ground Vehicle System Center, 6501 E. 11 Mile Road, Warren, MI 48397, USA
roughness, and dynamic interactions in the engine may play a role in this, highlighting that many potential nuances need consideration for the successful applications of these coatings. Keywords composites diesel engines microstructure thermal barrier coatings thermal conductivity thermal inertia thermal swing
Introduction The past decade has seen great developments in renewable and sustainable energy, with a large and committed global interest in pursuing environmentally friendly systems for energy storage and production. Amidst these developments, changes in energy systems for transportation are some of the most targeted. At its most extreme this is represented by potential legislation limiting the use of new gasoline and diesel vehicles for consumer transportation marked to start between 2020 and 2040 on the local and in some proposed cases national scales (Ref 1). Simultaneously, heavy machinery, industrial, military, and marine diesel are currently nearly indispensable and are expected to have considerably longer life spans by current projections (R
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