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, as shown in the figures.