Ultrasonic cavitation processing (USP) has gained a lot of momentum the last decade as an effective, environmental friendly and economical process. The basic principal of USP is conversion of acoustic energy into mechanical-impact energy by means of cavitation bubbles implosion and kinetic energy via acoustic streaming. However a broad application of this technology is hindered by the lack of understanding on the fundamental mechanisms governing USP. To this end our group undertook an extensive research program to elucidate and unveil the governing mechanisms behind USP that are necessary for process optimisation and scale up.
In this talk I present the recent results on our venture to understand and control USP for applications related to aluminium melt treatment and sono-exfoliation of graphite. Results showed that acoustic pressures decay with distance from the acoustic source though could be further amplified and maintained throughout the sonicated liquid metal domain if the right geometry (wavelength distance) is used. Our high-speed imaging results demonstrate for the first time that the fragmentation of intermetallics is a process associated with the propagation of shock waves from the collapsing bubbles. On the other hand a suitable combination of pressure, temperature and treatment time in a water/graphite solution promotes high quality relatively large (1 μm) graphene sheets.
Dr Iakovos Tzanakis holds the position of Reader in Engineering Materials at Oxford Brookes University, Oxford, UK and he is an Academic Visitor in the Materials Department at the University of Oxford (since 2013). His main field of research is the fundamentals and applications of ultrasonic cavitation processing in molten metals and the sono-exfoliation of 2D bulk layered materials with the potential of scaling-up these technologies for the production of high-quality metallic alloys and 2D functional nanomaterials such as graphene that are the promising and game-changing materials of the 21st century. He also works in the area of bio-inspired self-healing coatings for protection against cavitation erosion and on the emerging field of engineering emulsions and additive manufacturing.
Dr Tzanakis received his PhD in Tribology and Sustainability from Bournemouth University in 2010 and then worked as a Research Fellow in Bournemouth University (2010-2012) and as an EPSRC Fellow in Brunel University London (2013-2016). From April 2016, he was appointed as a Lecturer at Oxford Brookes University gaining promotions to Senior Lecturer (2017) and Reader (2018) in Engineering Materials. Dr Tzanakis has published more than 60 papers, of which more than half in peer-reviewed international journals and he is currently the principal investigator of two EPSRC projects (UltraMelt 2 and EcoUltra 2D).