Improvement of oxidation-resistance of NiCrAlY coatings by application of CrN or CrON interlayer

Abstract

NiCrAlY coatings with and without CrN or CrON interlayer as diffusion barrier were deposited on superalloy DSM11 by arc ion plating (AIP). The oxidation performance of the coating systems was evaluated by isothermal oxidation tests at 1100°C for 100 h. The element interdiffusion and oxidation behavior of the coating systems were described. It was found that the NiCrAlY coatings provided protective effect for the DSM11 substrate. However, serious interdiffusion between the coatings and substrate resulted in rapid degradation of the coatings. The addition of CrN or CrON interlayer between the coatings and substrate markedly decreased the interdiffusion. CrON interlayer performed better than CrN interlayer, which was attributed to the excellent diffusion barrier ability of Al 2 O 3 layer formed in the interlayer at high temperature. Also, the NiCrAlY/CrON coating system exhibited more effective protection for DSM11 than the NiCrAlY/CrN coating system.

Enhancement of the Corrosion Resistance of 304 Stainless Steel by Cr–N and Cr(N,O) Coatings

“…Different TM nitride coatings have been synthesised and investigated due to their high hardness, good oxidation resistance, and low wear rate in dry atmosphere, as well as their phase stability in corrosive environments [10,15,[33][34][35][36][37]. Oxynitride coatings have also been studied due to their plasmonic properties, relatively low electrical resistivity, good biocompatibility, and high oxidation resistance [25,[38][39][40][41][42][43][44][45][46].…”

Effects of the constitution of CrON diffusion barrier on the oxidation resistance and interfacial fracture of duplex coating system

“…It is known that a dense, continuous and closed-packed structure Al 2 O 3 exhibits outstanding diffusion barrier ability [4]. The presence of defects, such as grain boundaries, cracks and pores in the diffusion barrier will definitely decrease its competence due to the increase of short-circuit diffusion paths [14].…”

“…In previous studies [4][5][6][7][8] it was found that the coating system of MCrAlY overlayer with a CrN diffusion barrier had a strong interfacial strength, but the oxidation resistance of the duplex coatings was limited. On the other hand, the introduction of a pure Cr 2 O 3 diffusion barrier can suppress the interdiffusion with high efficiency due to the formation of a dense Al 2 O 3 interlayer during thermal treatment, although the interfacial strength is impaired by the presence of residual stresses.…”

“…Consequently, the MCrAlY coatings degrade rapidly after a long-term exposure to elevated temperatures. The main cause is ascribed to strong interdiffusion between the coating and the substrate [3,4]. The introduction of a diffusion barrier as an interlayer in the interface between the MCrAlY coating and the substrate is considered as the most effective solution to limit the interdiffusion and thereby prolong the service lifetime of the coating.…”

“…The investigations on diffusion barriers over the past two decades indicated that for a diffusion barrier to be excellent it should combine the good barrier ability with the strong adhesion to the substrate or the overlayer [3][4][5][6][7][8]. Developing a diffusion barrier which can markedly suppress the interdiffusion and does not weaken largely the interfacial strength of the coating system onto the substrate is a key for the practical application of diffusion barrier, so that diffusion barriers, such as RuNiAl and NiCrAlON with the close compositions to the overlayers were fabricated [5,6].…”