Development of energy intensive multifunction cavitation technology and its application to the surface modification of the Ni-based columnar crystal superalloy CM186LC

Toshihiko Yoshimura; Yuji Sugae; Takayuki Ogi; Fumihiro Kato; Masataka Ijiri

doi:10.1016/j.heliyon.2021.e08572

Development of energy intensive multifunction cavitation technology and its application to the surface modification of the Ni-based columnar crystal superalloy CM186LC

Heliyon. 2021 Dec 8;7(12):e08572. doi: 10.1016/j.heliyon.2021.e08572. eCollection 2021 Dec.

Authors

Toshihiko Yoshimura¹, Yuji Sugae¹, Takayuki Ogi¹, Fumihiro Kato¹, Masataka Ijiri²

Affiliations

¹ Department of Mechanical Engineering, Sanyo-Onoda City University, 1-1-1 Daigaku-dori, Sanyo-Onoda, Yamaguchi, 756-0884, Japan.
² Department of Mechanical Systems Engineering, Tokyo Metropolitan University, 1-1 Minami-Osawa, Hachioji, Tokyo, 192-0397, Japan.

Abstract

The present work demonstrates a technique for the hot forging of metal surfaces in water at 1000 °C or higher, termed energy-intensive multifunctional cavitation (EI-MFC). In this process, the energy of cavitation bubbles is maximized, following which these bubbles collide with the metal surface. This technique will be employed to improve the surface structure of CM186LC/DS, a Ni-based columnar crystalline superalloy used to manufacture the rotor blades of jet engines and gas turbines that are exposed to high-temperature oxidizing environments, with the aim of improving creep strength. EI-MFC processing induces compressive residual stress in the metal that prevents the occurrence of surface cracks and also increases surface hardness, improves corrosion resistance, and increases the coefficient of friction. The latter effect can enhance the adhesion of thermal barrier coatings applied to Ni-based superalloys by thermal spraying. The technology demonstrated herein can be applied to present-day jet engine and gas turbine components and also to the production of hydrogen combustion turbines operating at 1700 °C with higher combustion efficiency than the current 1500 °C class gas turbines. In addition, the high processing energy obtained using the EI-MFC technique has the potential to flatten rough surfaces resulting from the stacking pitches of various metals manufactured using three-dimensional printers, and so improve surface strength.

Keywords: Energy-intensive multifunction cavitation; High-temperature high-pressure cavitation; Multifunction cavitation; Ni-based superalloy; Rafting; Water jet cavitation.