Simulation Research on Residual Stress of Dual Ceramic Thermal Barrier Coatings for Aero-engine

It is an advanced method to optimize the design of dual ceramic thermal barrier coatings through finite element analysis with Abaqus. An optimized structure is achieved by comparing different pre-heating temperatures and varying the thickness of the dual ceramic coating under cooling condition, reducing the axial, radial and shear residual stress between interfaces of LaMgAl11O19 and YSZ, YSZ and NiCoCrAlY, NiCoCrAlY and K432A and also lowering the residual stress of LaMgAl11O19 surface. A 2D axisymmetric finite element model was constructed to simulate the real cooling situation of the sample. The thermal convection coefficient was fixed at 65 W/(m2·℃), and the thickness of both YSZ and LaMgAl11O19 was set to 150 µm. The pre-heating temperature of the substrate varied from 25 ℃ to 275 ℃ with an interval of every 50 ℃. As the sample approached the edge, the residual stress increased. The minimum axial stress at the edge appeared under 125 ℃ pre-heating, and the minimum shear residual stress was 8.2 MPa between 75 ℃ and 125 ℃. Next, the preheating temperature was set to 100 ℃, and the relative thickness of dual ceramic layers was changed. The total thickness maintained at 300 µm, with the thickness of YSZ varying from 0 µm to 300 µm in intervals of 50 µm and that of LaMgAl11O19 from 300 µm to 0 µm. Simulation results indicated that the maximum radial stress occurred when the thickness of LaMgAl11O19 was 300 µm and that of YSZ was 0 µm, while the maximum shear stress appeared when the thickness of LaMgAl11O19 was 0 µm and that of YSZ was 300 µm, and both situations led to the maximum axial stress. The structures of LaMgAl11O19 with a thickness of 300 µm and YSZ with a thickness of 0 µm resulted in compressive stress, while structures of LaMgAl11O19 with a thickness of 0 µm and YSZ with a thickness of 300 µm led to tensile stress and the minimum stress occurred when the thickness of both LaMgAl11O19 and YSZ was 150 µm, and the stress decreased significantly when the their thickness was similar. When the optimized design was used under a pre-heating temperature of 100 ℃ and a thickness of 150 µm for both LaMgAl11O19 and YSZ, the radial residual stress was much higher compared with the axial and shear residual stresses at the top surface of LaMgAl11O19 and along the radius of all interfaces at the position far from the edge. The radial residual stress initially decreased gradually when far from the edge and then decreased dramatically at the position near the edge. The axial and shear residual stresses remained relatively unchanged when the distance along the radius was less than 11 mm. However, both stresses changed rapidly as the position approached the edge. The maximum radial residual stress among different interfaces was 55.2 MPa and occurred at the interface between NiCoCrAlY and K432A, close to the edge of sample. The maximum axial and shear residual stresses also occurred at this interface, exceeding 13 MPa in both cases. It is observed that both the pre-heating temperature of substrate and the relative thickness of the dual ceramic coatings impact the residual axial, radial and shear residual stresses significantly during the cooling process. The pre-heating temperature between 75 ℃ and 125 ℃ and the similar thickness of LaMgAl11O19 and YSZ result in the minimum residual stress. The maximum residual stress occurs at the interface between NiCoCrAlY and K432A, indicating a reduced risk of ceramic coating peeling. © 2025 Chongqing Wujiu Periodicals Press. All rights reserved.