2023 Volume 79 Issue 6 Article ID: 22-00288
In steel highway bridges, the multi-layered overlapping coating was adopted in some cases, which applies paint on the sprayed coating. There are many unclear points about the durability and anti-corrosion properties of this overlapped coating film. In this study, to clarify the durability and anti-corrosion characteristics of overlapping layers between Al and Zn thermal sprayed coating and heavy duty paint coating, the specimens of single sprayed coating and overlapping coatings were prepared for the combined cyclic corrosion tests. A cross-cut coating defect was introduced into each specimen. After the test, the coating blister scans and electrochemical measurements on polarization were carried out on specimens, while the cross-section elemental analyses using SEM-EDX, and compound identification by XRD, etc. were also conducted. Test results indicate that the durability of Al overlapping layers is lower than that of the Zn overlapping layer, which deteriorated faster. Moreover, the degradation mechanism of the overlapping coatings between Al- or Zn-based sprayed coating and heavy duty paint coating was investigated, for those exposed to a highly corrosive and salinity environment.
