Densification behaviour of mixtures of hard and soft powders under pressure

The densification behaviour of mixtures of soft and hard powders during pre ssing is investigated. Several experimental studies using materials with mi scellaneous mechanical and morphological features are summarised. The influ ence of mixture characteristics on the densification kinetics is discussed and several mechanisms explaining the influence of hard particles on the de nsification behaviour are proposed. Two main cases are distinguished. When the applied pressure is low, with regard to the yield stress of soft partic les, the densification is mainly due to particle rearrangement and is favou red by a high fraction of hard particles. When soft particle deformation is the main densification mechanism, hard particles hinder the densification, with more or less significance depending on whether they are mostly isolat ed, are grouped in aggregates or form a percolating network. (C) 2000 Elsev ier Science S.A. All rights reserved.