Effect of zirconium addition on cyclic oxidation behavior of platinum-modified aluminide coating on nickel-based superalloy

Preparation and Isothermal Oxidation Behavior of Zr-Doped, Pt-Modified Aluminide Coating Prepared by a Hybrid Process

“…Some research showed that Zr tended to segregate around the NiAl grain boundary as Zr particles or combine with other elements in the form of compounds like Ni 7 Zr 2 , NiAl-Zr, or Al 5 Ni 2 Zr, etc. [12,16,26,27]. Combined with the XRD diffraction pattern shown in Figure 3 and the line scanning image ( Figure 5), it can be inferred that the Zr element might be partly saturated in the β-NiAl phase and partly co-segregated with Pt around the grain boundary of the β-NiAl phase.…”

“…It can be seen that the main phase of the PtAl and PtZrAl coatings is still β-NiAl, and the diffraction peaks of α-Al 2 O 3 emerge in the two coatings after oxidation for 2 h. The PtAl 2 phase is not detected, which might be because the PtAl 2 phase transforms into β-PtAl, and then changes to β-NiAl during the oxidation process [16]. As the oxidation time proceeds to 320 h, the diffraction peaks of the α-Al 2 O 3 become much stronger and the main phase of the two coatings transits to the γ'-Ni 3 Al phase, although the β-NiAl phase could still be detected.…”

Incorporation and evolution of ZrO2 nano-particles in Pt-modified aluminide coating for high temperature applications

“…Like other oxygen reactive elements, Zr is reported to have a similar effect to Hf [20,30,31] substrate, which could be the influence of Hf. Even though the Hf content in Mar-M-247 was much higher than the optimal value (500 ppm) [32,33], the growth of the TGO layer in both coatings was still retarded in case of Mar-M-247.…”

“…However, because Zr from the added ZrO2 particles was released by the reaction between Al and ZrO2, the effects of Zr from pure Zr addition and ZrO2 particles may be different. When pure Zr is incorporated by EB-PVD (electron beam physical vapour deposition) on a coating surface, the Zr-rich phase is formed after heat treatment and helps reduce the growth rate of TGO at early stages of oxidation [20]. However, Zr coming from ZrO2 particles, needs to diffuse first to the coating surface because ZrO2 particles are present inside the PtAl coating.…”

“…However, the investigation of Zr was mostly limited to alloys rather than coatings [16,19]. To date, only limited studies have reported the effects of Zr in PtAl coatings [20,21], and it should be noted that the methods used for introducing Zr are either costly or under development [20,22].…”