Can Bubbles Destroy a Solid Surface? PSU Physicist Comments on Ultrasonic Phenomena
Oscar Fattalov, a post-graduate student in Physics, explores the phenomenon of bubbles causing effect on the solid surface, as a result of ultrasound affecting the liquid layer underneath. The experiments will expand the fundamental knowledge in the field of hydrodynamics, acoustics and sonochemistry. The results can be applied to improve existing technologies for mineral processing using the flotation method.
“Every year the concentration of useful components in the extracted ores is getting poorer, making it necessary to look for new technologies, save-friendly to raw materials, helping to reduce waste and improve the quality of the resulting product. The use of ultrasound in the flotation process can improve the selectivity (purity) of the product. Our research allows to improve the quality of extracted ore, applying it to mineral processing by flotation, ” says Oscar Fattalov.
In addition, the results may be used in nano-structuring surfaces with specific properties, finding application in medicine and chemical production, contributing to development of innovative technologies and devices, as well as high-tech manufacturing.
The interdisciplinary study shares territories with sonochemistry (a section of chemistry that studies the progress of chemical reactions under the influence of ultrasound), fluid mechanics, and high-frequency acoustics. The study is aimed at finding new fundamental effects and gaining new knowledge in these areas.
As part of the study, the researchers immerse solid quartz plates pretreated with a surface-active substance (surfactant) into the water and aqueous solutions of salts, causing ultrasonic impact on them. Cavitation bubbles emerge in the liquid, affecting the dynamics of vapor-gas bubbles, creating fluid flows close to their surface and the surface of the plates. Consequently, using a high-speed camera and a digital microscope, the researchers observe the process at macro and micro scales.
“We are observing how a solid surface covered with a surfactant, degrades under the influence of ultrasound in liquids with various properties. We study the changes in surface properties, as well as the behavior of vapor-gas bubbles near such surfaces,” comments Oscar Fattalov.
The destructive Impact of cavitation might be illustrated through the surface of the propeller blades, degraded. The acoustic cavitation explored by Oscar Fattalov shows capacity of no less destructive character. Many issues related to the effects arising from ultrasonic cavitation have remained open for more than half a century.
“International researchers have been conducting similar research, based on interaction of cavitation bubbles with the surface, yet in the ordinary water, and the surface was processed mechanically. But what happens when a surfactant appears has not been studied before, and this is the main interest of the study, ” shares Oscar Fattalov.
The present experimental research is held as part of the grant competition of the Russian Foundation for Basic Research, titled "The best projects of basic scientific research carried out by young scientists studying in graduate school" on the basis of Perm State University, under the tutorship of Dr. Tatyana Lyubimova, professor at the Department of Theoretical Physics.
