Size Change of Very Fine Silver Agglomerates by Sintering in a Heated Flow.

The size change of silver agglomerate particles with diameters ≤100 mm during sintering is investigated. The growth rate of primary particles due to partial coalescence within an agglomerate is first derived based on a sintering theory. In the experiment, silver agglomerates uniform in electrical mobility-equivalent diameter are introduced into a heating pipe with N2 gas flow. The size changes of the agglomerates are measured using an aerosol technique. Agglomerates heated up to about 500 K (about 0.4 of the melting point) decrease steeply in size with temperature. The agglomerates which have fused into single particles begin to evaporate at a temperature >900 K. The measured change in diameter with temperature agree well with theoretical calculations in which suppression of sintering due to primary particle growth is taken into account.