Heteroaggregation of ceramic colloids in suspensions

The colloidal route is an important methodology in ceramic processing. A key step of the colloidal route is the aggregation of colloids in suspension. This often involves colloids of different types, in a process which is known as heteroaggregation. Here we review the recent developments in ceramic heteroaggregation, focusing on the physical mechanisms that cause it and on the structural properties of the resulting aggregates. Structural properties are analysed both on the local scale, at the level of nearest-neighbour contacts between colloids and on the long-range scale, at which percolating aggregates form, leading to gelification. Both experimental and simulation results are reviewed. The effects of the structure of the aggregates on the subsequent steps of ceramic processing are discussed.