Assessing dispersion stability of alumina colloids via thermal characterization of the sediment layer

Abstract

Colloidal suspensions incorporating particles are pivotal in diverse industries because of their distinct properties. However, challenges such as particle aggregation and sedimentation have impeded their widespread application. Existing techniques for assessing dispersion stability have limitations with respect to the particle type, concentration, and suspension properties. This study focuses on an innovative approach for assessing the dispersion stability and presents a streamlined method for analyzing the particle size and distribution. A theoretical model considering gravity, buoyancy, and viscous forces acting on the particles was developed to calculate the time-varying thickness of the sediment layer at the bottom of the sample colloid. The 3ω method is employed to measure thermal resistance changes at the sample droplet's bottom due to sedimentation. An empirical comparison utilizing Al2O3 particles in deionized water validates the efficacy of the method in understanding sedimentation mechanisms. In addition, a stability constant was proposed to quantitatively compare sedimentation phenomena, factoring in mixing methods, time, particle concentration, and shelf time. This study enhanced the quantification of the dispersion stability of colloids by enabling swift and precise assessment of particle concentration, size, and distribution inside a sample droplet.