Bulk material influence on the aggressiveness of cavitation : questioning the microjet impact influence and suggesting a possible way to erosion mitigation

Dular, Matevž (author), Ohl, Claus-Dieter (author)

In a study conducted over 10 years ago (Petkovsek and Dular, 2013) [1] we noticed that the thin metal sheet sustains less cavitation damage when it is attached to an acrylic glass (PMMA) than in the case when we attached it to quartz glass (SiO$_2$). The reason for this was not explored at the time. In the present paper we present a systematic study of single cavitation bubble erosion of a thin aluminum foil, which was attached to either PMMA or SiO$_2$ plate. We show that the damage sustained on the foil attached to PMMA plate is significantly smaller regardless of the bubble collapse distance from the boundary. The result is surprising since one would expect the weak foil to be severely damaged regardless of the material it is attached to. By femtosecond illumination and high-speed image acquisition we were able to capture the formation and progression of the shock waves, which are emitted at cavitation bubble collapse and observed that they are reflected on SiO$_2$ boundary but that they traverse the PMMA bulk material. We offer an explanation that to achieve less damage the bulk material needs to have acoustic impedance similar to the one of the liquid medium in which cavitation occurs. Further on, we constructed a simple composite material where PMMA was attached to the SiO$_2$ and showed that we can partially mitigate the damage. This was further confirmed by ultrasonic cavitation erosion tests. The results also imply that the cavitation damage originates solely from the shock wave, which is emitted at cavitation bubble collapse – consequently putting the idea of microjet impact mechanism under question. Finally, the study offers a new exciting approach to mitigate cavitation erosion by fine tuning the acoustic impedance of the coatings.

• Language: English
• Keywords: cavitation, bubbles, erosion, materials, acoustic impedance
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FS - Faculty of Mechanical Engineering
• Publication status: Published
• Publication version: Version of Record
• Year: 2023
• Number of pages: 9 str.
• Numbering: Vol. 530/531, art. 205061
• PID: 20.500.12556/RUL-148334
• UDC: 532.528:620.193.1
• ISSN on article: 0043-1648
• DOI: 10.1016/j.wear.2023.205061
• COBISS.SI-ID: 160334595
• Publication date in RUL: 17.08.2023

Record is a part of a journal

• Title: Wear
• Shortened title: Wear
• Publisher: Elsevier
• ISSN: 0043-1648
• COBISS.SI-ID: 5374213

Licences

• License: CC BY 4.0, Creative Commons Attribution 4.0 International
• Link: http://creativecommons.org/licenses/by/4.0/
• Description: This is the standard Creative Commons license that gives others maximum freedom to do what they want with the work as long as they credit the author.

Secondary language

• Language: Slovenian
• Keywords: kavitacija, mehurčki, erozija, materiali, akustična impedanca