Numerical simulation of the thermo-mechanical behavior of internal combustion engine piston with β-Si₃N₄/La₂Zr₂O₇ thermal barrier coating

In this study, β-Si 3 N 4 /La 2 Zr 2 O 7 (NLZ) thermal barrier coatings (TBCs) were fabricated via atmospheric plasma spraying. The mechanical properties and thermophysical properties of the coatings were experimentally investigated. Furthermore, the thermo-mechanical behavior of pistons with various TBC systems was numerically analyzed under simulated internal combustion engine operating conditions. The results indicate that the thermal conductivity of the NLZ coating varies between 0.40 and 1.24 W/(m·K) across the measured temperature range. Compared to the uncoated piston, the peak temperature of the NLZ-coated piston substrate was reduced by 15.5%, and the maximum Von Mises stress in the substrate decreased by 13.3%. Concurrently, the maximum principal and shear stresses within the NLZ bond coat were significantly lower, leading to a substantially reduced delamination risk at the edge of the combustion chamber compared to other coating configurations. Additionally, the deformation of the piston substrate was found to be negatively correlated with the thermal insulation capacity of the TBC. The application of the NLZ coating significantly mitigated structural deformation across various piston regions, thereby reducing the incidence of dry friction in critical tribological pairs, such as the piston-cylinder liner and piston pin-hole interfaces, ultimately extending the service life of the piston.