Sintering of particles of different sizes

A computer simulation study of the sintering process of cylindrical particles is presented following an earlier work by Pan et al. [Pan J, Le H, Kucherenko S, Yeomans JA. A model for the sintering of spherical particles of different sizes by solid state diffusion. Acta Metall 1998;46:4671-90]. The current paper focuses on the effect that the size of the particles has on the sintering kinetics. The computer simulation revealed a sophisticated behaviour for this apparently well-understood problem. Firstly, it is shown that a smaller particle can grow temporarily at the expense of its larger neighbours, in contradiction to conventional wisdom. There are two conditions for this to happen: (a) the particles must be nano-sized and (b) the smaller particle must be placed between two larger neighbours. Secondly, a pair of nanoparticles of different size can separate from each other in the later stage of their co-sintering process. Thirdly, the extent to which particles approach each other is strongly influenced by degree of constraint that the particles are subjected to by the neighbouring particles. This sophisticated behaviour revealed by the computer simulation questions the relevance of the oversimplistic sintering models to a real powder compact.