On the governing fragmentation mechanism of primary intermetallics by induced cavitation

Characterization of shock waves in power ultrasound

“…To further examine the measured shock wave frequency, using the Schlieren (Settles 2012; Möller, Degen & Dual 2013) method, we analysed the high-speed images of shock wave emission to extract the wavelength of the disturbance and consequently the frequency. Figure 3 shows a snapshot of a propagation of the shock wave along with the distribution of optical intensity across the shock wave (distance d from point a towards b ).…”

“…The intensity profile shows a full cycle of the wave from which the wavelength and consequently the frequency of the emission can be measured. The optical intensity is proportional to the second derivative of the index of rarefaction (Evans 1990; Settles 2012) as well as that of pressure (Chamanzar et al. 2019).…”

“…Shock waves are of importance due to their extreme dynamics, and underpin many of the applications that utilize acoustic cavitation, notably melt treatment (Meyers, Gupta & Murr 1981;Tan et al 2015;Eskin & Mi 2018;Eskin et al 2019), sonochemistry (Suslick 1990), lithotripsy (Church 1989;Zhong, Chuong & Preminger 1993;Vogel 1997;Bailey et al 2005;Cleveland & McAteer 2007;Kobayashi, Kodama & Takahira 2011;Pishchalnikov et al 2019), ocular surgery (Vogel et al 1986), food processing (Long 2001) and pharmaceutics (Dalecki 2004;Menezes et al 2008), to name but a few. Furthermore, it has recently been discussed, as part of the present studies, that shock wave emission is the governing mechanism for intermetallics fragmentation (Priyadarshi et al 2020) as well as for graphite exfoliation (Morton et al 2021). However, the key properties of cavitation-driven shock waves and the underlying shock wave mechanisms are not well understood and therefore remain a topic of great interest.…”

Understanding the relationship between particle size and ultrasonic treatment during the synthesis of metal nanoparticles

“…The collapse and rebound of a cavitation bubble can produce strong shock waves and extremely high pressure [26] . In liquid aluminum, the pressure of the shock waves can reach the order of Megapascal [27] , [32] , [33] . These effects can promote the fragmentation and de-aggregation of the particles.…”

Scale up design study on process vessel dimensions for ultrasonic processing of water and liquid aluminium

“…Ultrasonic cavitation melt treatment (UST) is an environmentally friendly, economical and sustainable technique [1] , [2] , [3] that has been shown to benefit the microstructure and mechanical properties of metallic alloys upon casting. The salient mechanism is related to the phenomenon of acoustic cavitation that aids structural refinement by heterogeneous nucleation through the activation of the solid particles and substrates [1] , [2] , deagglomeration [4] , dispersion [2] , [5] , [6] , fragmentation [7] , and also leads to degassing of the treated melt [8] . The acoustic pressure amplitude and distribution generated by the immersed sonotrode and the resultant extent of cavitation region are the main process parameters that need to be controlled and optimised.…”