|
Type |
Oral Presentation |
Area |
Oral Presentation of Young Inorganic Chemists |
Room No. |
Samda Hall B |
Time |
THU 09:40-: |
Code |
INOR.O-3 |
Subject |
Sonofragmentation of Ionic Crystals |
Authors |
Hyo Na Kim, Kenneth S. Suslick* Chemistry, University of Illinois at Urbana-Champaign, United States |
Abstract |
When ultrasound is applied to a liquid, acoustic cavitation occurs; bubbles are generated, oscillate, expand and, when specific criteria are met, implosively collapse. If a bubble collapses near a significantly larger surface or particle, the bubble collapses asymmetrically and a high-speed liquid stream with a velocity > 100 m/s is generated (i.e., microjet). The liquid moves toward the surface of the solid material in the solid-liquid mixture and deforms it or changes its chemical composition. Also, shockwaves, generated from acoustic cavitation, can cause high velocity collisions between micron-sized solid particles (i.e., interparticle collisions) or directly interact with particles inducing breakage (i.e., sonofragmentation).
In this work, the breakage of ionic crystals was quantitatively investigated when ultrasound was irradiated to the slurries of ionic crystals. There was strong correlation between the strength of the materials (as measured by Vickers hardness or by Young’s modulus) and the rate of fragmentation of the ionic crystals. This is a mechanochemical extension of the Bell–Evans–Polanyi Principle or Hammond’s Postulate: activation energies for solid fracture correlate with binding energies of solids. In addition, it was confirmed that a direct interaction between the shockwaves and the ionic crystals in the slurries was the major mechanism of the particle breakage. Detailed mechanism of the fragmentation was proposed to occur from defects in the solids induced by compression-expansion, bending, or torsional distortions of the crystals.
|
E-mail |
hyona8318@naver.com |
|