Residual stresses and final deformation of an alumina coating: Modeling and measurement

•A 3D finite element model with a Gaussian coating profile is proposed using ANSYS.•The effective properties of alumina coating were used in this model.•The residual stress state at different deposition time is predicted.•A high cooling rate could efficiently reduce the final deflection of the specimen.•The convection coefficient of 20 W·m− 2·K− 1 is more reasonable for this model.

Mechanical performances of multi-layer coatings are directly affected by thermal history and subsequent residual stress distribution within the sample during thermal spray process. In the present work, a 3D multi-layer model of the plasma spray process was developed to study the thermal and mechanical evolutions of the specimen. The coating build-up was performed by progressive activation of coating layers with a Gaussian distribution profile measured from the corresponding coating. The contribution of sprayed particles to the substrate heating was thus taken into account using a heat flux presenting a Gaussian distribution profile. The decrease of the coating effective properties caused by the presence of porosities and microcracks was investigated by measurement and calculation works. As a result, the temperature evolution, residual stress distribution and final displacement field of the specimen were predicted. At the end of the deposition process, a tensile stress with small magnitude was obtained within the alumina coating. However, the residual stress was turned to a compressive state within the coating after cooling to ambient temperature. A higher cooling rate was found to result in a lower temperature magnitude of the specimen, a lower residual stress within the coating and a lower displacement field of the specimen. The simulated deflection of the specimen was found to agree well with the experimental measurements.