Sintering of Polydisperse Nanometer-Sized Agglomerates

Abstract

In order to evaluate the sintering characteristics of polydisperse TiO₂ and SiO₂ fractal agglomerates consisting of nm-sized primary particles (nanoparticles), the change in size distribution of agglomerates in a heated pipe is measured using a differential mobility analyzer and a condensation nucleus counter. Change in the structure and the primary particle size of the agglomerates collected by a thermophoretic aerosol sampler is also measured by the transmission electron microscopy as a function of furnace temperature. Coalescence of the agglomerates and the growth of primary particles due to sintering are observed at temperatures corresponding to 50%–100% of the bulk melting points of the particle material. To model the changes in the size distribution of agglomerates and primary particles due to sintering, two-dimensional sectional representation of the size distribution is employed, and the population balance equation for sintering is solved numerically. The calculated results, considering a well-defined temperature history of the agglomerates, successfully explain the observed changes in the particle-size distribution and agglomerate structure.