Abstract
The mechanism of oxidation protection of NiCoCrAlY overlay coatings on the orthorhombic Ti 2AlNb-based alloy (O alloy) Ti–22Al–26Nb (at.%) is described. While the bare alloy exhibited poor oxidation resistance at 800 °C, adding NiCoCrAlY coatings significantly improved the oxidation resistance. However, serious interdiffusion between the coatings and the substrate resulted in rapid degradation of the coating system. Several reaction layers were formed at the coating/substrate interface by interdiffusion, and non-protective scales mainly of Cr 2O 3 and TiO 2 were formed due to the degradation of the coating. In order to solve this problem, an Al 2O 3/Al interlayer was sandwiched into the coating system as a diffusion barrier. The isothermal and cyclic oxidation protection of the multilayer coating system on the Ti–22Al–26Nb substrate was evaluated at 800 and 900 °C. The results indicated that the interdiffusion was much suppressed, and the duplex coating system demonstrated improved oxidation resistance on the Ti–22Al–26Nb substrate, with a thin and adherent protective α-Al 2O 3 scale forming on the surface.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
