Interface stress calculation and failure behavior of TBCs on the surface of aluminum alloy with anodic oxidation

Abstract

Aluminum protective coatings have poor performance due to the significant difference in coefficient of thermal expansion (CTE) between the substrate and the coating. In this study, porous anodic aluminum layer, which have high bonding, well matching and grew in situ on the substrate of aluminum alloy (4032) using anodic oxidation, and then thermal barrier coatings were produced on the surface by laser surface modification and atmospheric plasma spraying (APS). The aim of this way is to improve the interface thermal shock resistance (TSR) of the coatings. The results showed that the coatings with anodic aluminum layer (highest group average of 444 cycles) have a much higher number of thermal shock cycles than metallic bond coatings. Furthermore, the failure analysis suggested that the bonding stability of the coatings is influenced by the surface state, surface mosaic structure, as well as such as CTE and surface roughness. Eventually, a double-layer mismatch stress model was developed to characterize the residual stresses caused by deformation mismatch in the coatings. After performing calculations，from a force perspective τa≈10τb, and from a work perspective Wfa≈3.34Wfb.