Cavitation-Assisted Particle Dispersion

1 Introduction

Common hydraulic definitions, energy boundaries, residence-time expressions, uncertainty requirements, and scale-translation principles are consolidated in Section 6.2. The present article adopts that framework and develops the mechanisms, models, and acceptance criteria specific to cavitation-assisted particle dispersion.

Particle dispersion and deagglomeration are critical operations in the manufacture of catalysts, ceramic slips, electronic inks and pastes, battery suspensions, nanofluids, pharmaceutical formulations, pigments, coatings, polymer composites, thermal-interface materials, food slurries, and two-dimensional materials. The engineering objective is not simply to reduce an instrument-reported diameter. A successful process must generate a reproducible dispersed-particle population, control the coarse tail of the particle-size distribution, preserve the required morphology and crystal structure, and maintain chemical stability at newly created solid-liquid interfaces.

Hydrodynamic cavitation provides a distinctive combination of mechanical stresses for these purposes. Acceleration through a restriction or a rapidly varying flow field can lower local static pressure sufficiently to generate vapor or gas-filled cavities. The cavities grow, convect, interact with suspended solids, and collapse during pressure recovery. Collapse produces pressure pulses, shock waves, liquid microjets, intense velocity gradients, turbulent dissipation, and rapid particle acceleration. In combination, these effects can separate weak agglomerates, erode aggregate surfaces, fracture brittle crystals, exfoliate layered materials, remove attached contaminants, and modify the collision history of suspended particles [1,3,7,8,14].

Cavitation is not beneficial under all operating conditions. Excessive exposure can fracture primary particles, shorten fibers, reduce flake aspect ratio, remove functional coatings, alter crystal structure, accelerate equipment wear, increase bulk temperature, or promote reaggregation after new surfaces are formed. Cavitation has also increased the coarse-particle population in chemically sensitive chemical mechanical planarization slurries [37]. Process development must therefore control the cavitation field, particle mechanics, suspension rheology, surface chemistry, residence-time distribution, temperature, gas content, and downstream handling as coupled variables.

This article presents an engineering framework for hydrodynamic cavitation-assisted particle processing. It distinguishes deagglomeration from comminution, describes the physical and colloidal mechanisms that control dispersion, summarizes the principal governing relations, compares equipment configurations, reviews analytical methods and quantitative case studies, and provides procedures for scale-up and troubleshooting.