Cyclic oxidation behavior and oxide scale adhesion of Al/NiCrAlY coating on pure titanium alloy

Abstract

Al and Al/NiCrAlY coatings were deposited on pure titanium substrate by air plasma spraying method. Cyclic oxidation behavior and oxide scale adhesion at 800 °C for 100 cycles were investigated. For the single Al coating, a severe spalling of oxide scale and elemental interdiffusion occurred after 100 cycles. The mass loss of the single Al coating has reached to 1.39 mg/cm2. The oxide scale on the duplex Al/NiCrAlY coating kept a good bonding with the underlay coating. The addition of NiCrAlY layer inhibited the outward diffusion of Ti atoms and inward diffusion of Al atoms. The propagation of cracks and the formation of pores were also suppressed by NiCrAlY layer. As a result, the duplex Al/NiCrAlY coating possessed a superior cyclic oxidation resistance.