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

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.

Precise Peening of Ni-Cr-Mo Steel by Energy-Intensive Multifunction Cavitation in Conjunction With Positron Irradiation

“…The diameter of the nozzle used in this work was 0.2 mm, the WJ pressure was 22 MPa and the flow rate was 195 mL/min. The instrumentation employed in previous work Yoshimura et al (2021a), Yoshimura et al (2022b) incorporated a nozzle having a diameter of 0.8 mm along with a flow rate of 7 L/min to generate a swirling flow based on the inflow of surrounding water . The use of a nozzle diameter of 0.8 mm and a flow rate of 7 L/min increased both the WJ bubble diameter and the microjet impact pressure.…”

“…Under these conditions, the MFC processing involved both a Coulomb force and a bell-shaped cavitation jet. In addition, ultrasonic radiation was applied using a pentagonal geometry to prevent the radiation sources from directly facing one another (as occurs in the EI-MFC device) and to avoid sound pressure interference or cancellation Yoshimura et al (2021a). The 72 neodymium magnets were arranged in a heptagonal geometry based on previous work using the MEI-MFC Yoshimura et al (2022b) and LMEI-MFC techniques Yoshimura et al (2023b).…”

“…In the case that a magnetic field is applied to these bubbles, the Lorentz force acts in the liquid flow direction, promoting collisions between the bubbles Yoshimura et al (2022a) that generate new bubbles so as to improve the material processing ability of the system. The authors also previously developed an energy-intensive MFC (EI-MFC) technology Yoshimura et al (2021a) that concentrates the ultrasonic irradiation generated in the vicinity of WJC bubbles, together with an MEI-MFC apparatus that applies a magnetic field to the EI-MFC process Yoshimura et al (2021a). A new metal processing technique referred to as laser-assisted EI-MFC (LMEI-MFC) was also demonstrated in prior studies Yoshimura et al (2021b), Yoshimura et al (2022b).…”

Fusion Induced by Energy-Intensive Multifunction Cavitation in Conjunction With Positron Irradiation

“…It is possible to increase the internal temperature and pressure of cavitation bubbles by applying concentrated ultrasonic radiation from the periphery of a conventional WJC jet rather than from only one direction Yoshimura et al (2021b). This technique was used to develop an energy-concentrating multifunction cavitation system in which five ultrasonic transducers are arranged around a water jet.…”

Modifying Resin Viscoelasticity by Multifunction Cavitation Processing in a Magnetic Field

“…The bubble temperature and pressure obtained during MFC were later improved by employing a swirl addition nozzle Yoshimura et al (2018b) In the case of the ultrahigh-temperature and high-pressure cavitation method Yoshimura et al (2018a) Yoshimura et al (2021a a water jet flow associated with water jet cavitation is irradiated with ultrasonic waves from one direction. We have also demonstrated an energy-intensive MFC (EI-MFC: Energy Intensive Multifunction Cavitation) technology in which ultrasonic waves are applied from the circumferential direction of the jet flow Yoshimura et al (2021b) In addition, the charged bubble phenomenon that occurs during MFC Yoshimura et al (2016) Yoshimura et al (2018a) has been employed to devise a concentrated energy MFC technology involving the application of a strong magnetic field (MEI-MFC: magnetic energy intensive multifunction cavitation) Yoshimura et al (2022) This technique uses a large-scale apparatus with a water jet nozzle diameter of 0.8 mm and a flow rate of approximately 7 L/min that generates larger bubbles with radii of up to several hundred micrometers. Although this process is suitable for the surface modification of metals, its application to the synthesis of photocatalyst powders or similar materials is time consuming and does not allow the generation of high-purity products.…”