Effect Coating Thickness and the Sealant on the Steam Oxidation Resistance of APS Ni-Cr Coatings

摘要

In our earlier studies we reported the excellent steam oxidation resistance of 50Ni-50Cr coatings produced by highvelocity oxyfuel (HVOF) spray process. The coating produced by atmospheric plasma spray (APS) for the thicknessof 40 μm yielded the scale incorporation into the coating structure on the steam oxidation due to its porousstructure compared to HVOF process. The steam could penetrate into the pores and resulted in the scale initiationat the coating-substrate interface. To improve the steam oxidation resistance of the coating, thick coatings (～450μm) of 50Ni-50Cr with sealant layer were tested in the steam. The sealant layer was applied to fill the poresproduced by the APS process. The results showed that the thick coating of 50Ni-50Cr with sealant was able toprotect against the steam oxidation till 3000 hours of tested duration.