The numerical simulations clearly show that temperature and thermal stress distribution are a function of coating
thickness. For all the coating thicknesses, the highest temperature appeared at the crown center and on the edges of the
bowl rim on the top surface of the coating and on the piston surface. The temperature at the surface of the coated region
is significantly higher than that of the uncoated piston surface. Increase in the maximum temperature at the crown
center, compared with the uncoated piston, is 32.7%, 55.8%, 72.5% and 84.8% for 0.4 mm, 0.8 mm, 1.2 mm and 1.6
mm thick coating, respectively. It is clear that a higher combustion chamber temperature is provided by means of TBC.
As a result, thermal efficiency of the engine increases. Moreover, reduction of the piston (substrate) surface
temperature has a positive effect on engine performance. It is quite obvious that the maximum thermal stress is a
function of coating thickness. The maximum normal and shear stress components occur in the bond coat. The results
indicate that thermal stress is related to coating thickness. It increases with the coating thickness on the SUBS. The
greatest value of the normal stress which produces spalling of the ceramic is produced on the bond coat. It is nearly
twice the value of the maximum normal stress on the substrate. As seen here, thermal performance of the piston
increases with increased coating thickness. When stress values obtained from FEA are compared with the mechanical
properties of the aluminum alloy and zirconia material, it can be seen that calculated stress values are lower than the
allowable stress values of the materials.