Cold Sprayed Intermetallic Based Multilayer Thermal Barrier Coatings For Engine Pistons

Thermal Barrier Coatings (TBC) are used to reduce the thermal flux from the combustion chamber to other parts of the engine, allowing a higher temperature in the combustion chamber and increased efficiency. Ceramic coating based on yttrium stabilized zirconia are used most frequently in auto- and aero- industries for internal combustion engines and turbo engines.

The inclusion of metallic components in the TBC that makes them less brittle and less susceptible to degradation while providing the same insulating properties of ceramic barrier coatings it is a matter of strong interest in the industry.

Our group is developing multilayer TBC based on intermetallic (Fe-Al) compounds combined alternating with zirconia or mullite based layers. The layers are deposited by cold spray techniques on the surface of pistons used in gasoline and Diesel engines. The composition of the layers is further modified by bulk sintering in nitrogen atmosphere or by surface sintering using laser scanning. The microstructures are investigated by optical and electron microscopy. The thermal conductivity of the TBC was measured by a constant thermal flux method.