ORALS

SESSION: CorrosionTueAM-R7	Macdonald International Symposium (Intl Sympos. on Corrosion for Sustainable Development)
Tue. 29 Nov. 2022 / Room: Andaman 2
Session Chairs: Shujiang Geng; Session Monitor: TBA

12:45: [CorrosionTueAM04] OS
HIGH COMPATIBILITY of NANOCRYSTALLINE COATINGS with SINGLE CRYSTAL SUPERALLOYS for HIGH TEMPERATURE APPLICATIONS
Shenglong Zhu¹ ; ¹Institute of Metal Research, Chinese Academy of Sciences, Shenyang, China;
Paper Id: 215 [Abstract]

Strong interdiffusion between protective coatings and superalloy substrates at high temperatures leads to formation of secondary reaction zone (SRZ), which may seriously weaken the creep and fatigue properties of the coated components[1-3]. In this talk, a serial of nanocrystalline coatings will be introduced to show their high substrate-coating compatibility in addition to excellent oxidation resistance at 1100 ºC. The coatings were prepared on Ni-base single crystal superalloy Rene N5 using magnetron sputtering, and their chemical composition were derived from Rene N5. The thermally grown oxide (TGO) grew on the coating with chemical composition same as Rene N5 is alumina with dispersive TaOx, which is harmful to the oxidation resistance. Increasing the Al concentration to decrease the Ta content in the γ' phase of the coating can reduce the amount of the TaOx in TGO while either making a single γ' phase coating or decreasing the Ta in the coating can prevent the formation of TaOx in TGO. The β phase in the coatings should be prohibited, since it is the driving force to form SRZ.

References:
1. T. Narita, A View of Compatible Heat-Resistant Alloy and Coating Systems at High-Temperatures, International Workshop on Advanced Material for New and Renewable Energy, Jakarta, INDONESIA, JUN 09-11, 2009; AIP Conference Proceedings 1169 (2009)‏ 63-73.
2. F. H. Latief, K. Kakehi, Influence of thermal exposure on the creep properties of an aluminized Ni-based single crystal superalloy in different surface orientations, Materials and Design 56 (2014) 816–821.
3. A.G. Evans, M.Y. He, A. Suzuki, M. Gigliotti, B. Hazel, T.M. Pollock, A mechanism governing oxidation-assisted low-cycle fatigue of superalloys, Acta Materialia 57 (2009) 2969–2983.

SESSION: CorrosionTuePM1-R7	Macdonald International Symposium (Intl Sympos. on Corrosion for Sustainable Development)
Tue. 29 Nov. 2022 / Room: Andaman 2
Session Chairs: Junhua Dong; Session Monitor: TBA

14:00: [CorrosionTuePM105] OS
Designing High Temperature Protective Bondcoat for Ni-base Single Crystal Superalloys
Zebin Bao¹ ; Shenglong Zhu¹ ; Fuhui Wang² ; ¹Institute of Metal Research, Chinese Academy of Sciences, Shenyang, China; ²Northeastern University, Shenyang, China;
Paper Id: 216 [Abstract]

To meet the sustaining request of enhancing thrust-load ratio, single crystal (SX) superalloy, film cooling and thermal barrier coating system (TBCs) have been perspectively utilized in advanced areo engines. Usually, the coating system consists of an oxidation resistant bondcoat and a heat resistant top coat. During service of SX superalloy components at high temperature, the element interdiffusion between bondcoat and superalloy substrate may instigate serious deterioration of mechanical property (e.g., creep resistance and rupture life) of SX superalloy by forming topologically-close-packed (TCP) phases and second reaction zone (SRZ) [1]. Another impact of such interdiffusion is the loss of beneficial element and undesirable oxidation of refratory elements at surface [2]. Thus, to inhibit or mitigate the interdiffusion is one of the key points to design protective bondcoat for Ni-base SX superalloys [3]. In this study, a Re-base diffusion barrier (DB) has been sucessfully incorporated between the state-of-the-art bondcoat of (Ni,Pt)Al and the Ni-base SX superalloy. In contrast to normal (Ni,Pt)Al coating, the coating with Re-base DB showed better oxidation resistance and less interdiffusion, which further resulted in thinner formation of SRZ and TCP precipitates. Mechanisms responsible for the enhanced performance during the oxidation tests will be intensively discussed.

References:
[1] D.K. Das, K.S. Murphy, S. MA, T.M. Pollock, Formation of secondary reaction zones in diffusion aluminide coated Ni-base single-crystal superalloys containing ruthenium, Metall. Mater. Trans. A 39 (2008) 1647–1657.\n[2] N. D. Souza, D. Welton, G.D West, I.M. Edmonds, On the roles of oxidation and vaporization in surface micro-structural instability during solution heat treatment of Ni-base superalloys, Metall. Mater. Trans. A 45 (2014) 5968–5981.\n[3] C.A. Guo, W. Wang, Y.X. Cheng, S.L. Zhu, F.H. Wang, Yttria partially stabilised zirconia as diffusion barrier between NiCrAlY and Ni-base single crystal René N5 superalloy, Corros. Sci. 94 (2015) 122–128.