Plasma electrolytic oxidation thermal barrier coating for reduced heat losses in IC engines

The work involved the development and on-engine testing of a new “thermo-swing” barrier coating for reduced wall heat transfer increased thermal efficiency in future diesel engines utilizing aluminium alloy pistons. Such swing coatings, low conductivity specific capacity, have recently been proposed to produce dynamic layer that rapidly changes temperature upper surface piston crown response adjacent in-cylinder gas temperature. tested this was formed directly from substrate material using an optimised plasma electrolytic oxidation process, with silica top coat subsequently applied entrap air within pores. Benchtop laser flash measurements were undertaken quantify properties provide required empirical data simulation. Coatings varying features bespoke thermodynamic single cylinder engine instrumented precision pressure, fuel consumption legislated engine-out emissions. optimum across full bowl enabled up 3% improvement indicated under idealised part load operating conditions. during combustion, leading elevated NOx. By retarding combustion phasing slightly optimum, NOx increase could be mitigated while still retaining most benefit, remaining benefit associated power stroke. emissions other key pollutants (CO, unburned hydrocarbons soot) less affected conditions tested.