Adhesion and residual stress of plasma sprayed Alumina–titania coatings

Abstract

Plasma-sprayed coatings are formed by the impacting of particles onto a fixed substrate layer-by-layer. Residual stresses inside the coatings are essential for their influencing on the coatings’ performance and durability during service life. In the present work, heat transfer and elastic–plastic residual stresses generation during plasma spraying in Al2O3–13wt.%TiO2/NiCrAl (AT13) coating system were analyzed by finite element analysis (FEA). The sophisticated spraying process was simulated and the laminated structure of the coating was modeled under three-dimension. In this simulation, radial and axial compressive stresses were concentrated at the interfaces and inside the bond layer. Besides, at the specimen corner of the free edge, there were high tensile radial and axial stress concentrations. Such remarkable stresses, no matter tensile or compressive, may lead to the delamination and failure of coatings. Comparing with the numerical results, X-ray diffraction measurement was conducted on the AT13 coatings. As a result, the tested values matched well with the FEA simulated results.