Thin thermal barrier coatings for internal combustion engine components

Contrary to the thick thermal barrier coating approach used in insulated diesel engines, this paper investigates the merits of thin coatings. Transient heat transfer analysis indicates that the temperature swings experienced at combustion chamber surfaces depend primarily on material thermophysical properties, i.e. conductivity, density, and specific heat. Thus, cyclic temperature swings should be alike whether thick or thin (less than 0.25 min) coatings are applied. Furthermore, thin coatings would lead to lower mean component temperatures and would be easier to apply than thick coatings. The thinly–coated engine concept leads to modest improvements in brake power, lower exhaust emissions, and higher exhaust temperatures for possible exhaust gas utilization. Other gains include improved piston–liner tribological behaviour, improved erosion–corrosion resistance, and thus greater component durability. Above all, thin coatings may find application in the large gasoline engine market.