DEPENDENCE OF OSTWALD RIPENING KINETICS ON PARTICLE-VOLUME FRACTION

A spatially homogeneous rate theory model is developed to describe the time rate of change of the radius of a spherical particle embedded in a configurationally random array of particles of like nature but differing sizes. The growth rate so derived is incorporated within the Lifshitz-Slyozov and Wagner hydrodynamic model of particle coarsening and the asymptotic size distribution determined as a function of the particle volume fraction, φ. In agreement with earlier workers, it is shown that for diffusion-controlled coarsening the basic kinetic form r ̄3~Kt relating the mean particle radius, r̄, to the time, t, is maintained, with the rate constant K a function of the volume fraction. Derived values of K are, however, much less sensitive to φ than suggested by prior treatments and are thus shown to be more generally compatible with experimental observation. A critical test of the theory must await the acquisition of more accurate data than has been obtained hitherto. © 1979.