20.500.12556/RUL-148334 Bulk material influence on the aggressiveness of cavitation questioning the microjet impact influence and suggesting a possible way to erosion mitigation 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. cavitation bubbles erosion materials acoustic impedance kavitacija mehurčki erozija materiali akustična impedanca true false true Angleški jezik Slovenski jezik Članek v reviji 2023-08-17 09:24:07 2023-08-17 09:24:12 2024-02-13 10:01:27 0000-00-00 00:00:00 2023 0 0 9 str. Vol. 530/531, art. 205061 Oct. 2023 0000-00-00 Zaloznikova Objavljeno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 532.528:620.193.1 0043-1648 10.1016/j.wear.2023.205061 160334595 Dular,_Ohl_-Bulk_material_influence_on_the_aggressiveness_of_cavitation.pdf Dular,_Ohl_-Bulk_material_influence_on_the_aggressiveness_of_cavitation.pdf 1 D263C5573F15731C47772004961156F8 afd3d761d96261cc1fd42ae7f22482cc5f5d75b8089f6fc53b35fa9f80e2777d f8aa95f1-3ccf-11ee-b9d7-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=172457 https://www.sciencedirect.com/science/article/pii/S0043164823004441 1 0b6e3b20-3ccf-11ee-b9d7-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=172456 Fakulteta za strojništvo 0 0 0