Nanoparticle dispersion in liquid metals by electromagnetically induced acoustic cavitation


Nanoparticle dispersion in liquid metals by electromagnetically induced acoustic cavitation

Kaldre, I.; Bojarevics, A.; Grants, I.; Beinerts, T.; Kalvans, M.; Milgravis, M.

Ceramic nanoparticle dispersion in metallic matrix is a technical challenge to produce class of composite materials-Metal matrix nano-composites (MMNC). Current powder metallurgy has limitations producing these materials. Process is time consuming and dimensions of ingots are limited. Aim of this study is to investigate experimentally the effect of magnetically induced cavitation applied for the purpose of nanoparticle dispersion in liquid metals. We present a contactless electromagnetic method to induce ultrasound and disperse particles in liquid metals by simultaneously applied steady and alternating magnetic fields. The oscillating magnetic force due to the azimuthal induction currents and the axial magnetic field excites power ultrasound in the sample. If the fields are sufficiently high then it is possible to achieve the acoustic cavitation threshold in liquid metals. Cavitation bubble collapses create intense microscale jets, which can break nanoparticle agglomerates and disperse them. Cavitation bubble collapses are known to create microscale jets with a potential to break nanoparticle agglomerates and disperse them. The samples are solidified under the contactless ultrasonic treatment and later analyzed by electron microscopy and energy-dispersive X-ray spectroscopy (EDX). It is observed that SiC nanoparticles are dispersed in an aluminum magnesium alloy, whereas in tin the same particles remain agglomerated in micron-sizedclusters despite a more intense cavitation.

Keywords: Nanaoparticles; Metal matrix composites (MMCs); Cavitation; High magnetic field; Power ultrasound

Permalink: https://www.hzdr.de/publications/Publ-23969
Publ.-Id: 23969