Kumiko Tanaka

By Toshihiko Yoshimura, Kumiko Tanaka and Masataka Ijiri

Titanium oxide particles were treated by water jet cavitation (WJC) generated and multifunction cavitation (MFC) using an ejector nozzle. Generation, growth, and collapse of cavitation are repeated with the particles of titanium oxide and platinum. Because the cavitation has an extremely high collapse pressure, the surface of the titanium oxide particles is processed by the microjets of cavitation in a reactor comprising the ejector nozzle. In the multifunction cavitation, ultrasonic irradiation of a waterjet during floating cavitation was used to generate microjets with hot spots. Hot working can be performed at the nanoscale on a material surface using this MFC process, resulting in morphological changes and variations in the surface electrochemical characteristics. The fundamental characteristics of multifunction cavitation were investigated theoretically and experimentally. Furthermore, the additional nozzle was put on the ejector nozzle in order to increase the temperature and pressure of bubble and the mechanism was clarified. The quantities of hydrogen and oxygen generated from titanium dioxide particles treated by multifunction cavitation in response to UV and visible light irradiation were remarkably increased compared to the amounts produced by particles treated by WJC processing. In this chapter, the methods and their results of processing particles by cavitation are introduced.

Part of the book: Cavitation