The innovation engine for new materials

The Role of Colloid and Interface Science in Ceramic Powder and Mineral Processing

Seminar Group: 


Professor George V. Franks


Chemical and Biomolecular Engineering,
University of Melbourne, Australia


Friday, September 23, 2011 - 4:00pm


ESB 1001

The ability to control colloidal particle interactions in suspensions is crucial in controlling suspension rheology. By choosing surface chemical additives, suspension behaviour can be controlled at different stages of the process to enable a wide variety of innovative processes. Additives which can be used to switch behaviour, for example by change in temperature, are particularly useful. A novel gelcasting system has been developed which allows a high volume fraction suspension with low viscosity to be shaped and then gelled into a solid-like material to produce monolithic ceramic bodies and ceramic tapes. Control of the particle surface hydrophobicity can further be used to produce cellular (porous) ceramic materials. The gelation of the polymeric binder strengthens the green body and reduces the occurrence of drying cracks. The uniform and dense packing of particles in the green body enables pressureless sintering of difficult to densify ceramics such as ultra high temperature ceramics for hypersonic rocket applications. Densification with out the application of pressure via graphite die allows for reduced processing cost and complex shape forming capability. Temperature responsive flocculants have been developed to aid in the recovery and reuse of water from mineral tailings. The use of poly (N-isopropyl acrylamide) which acts as a flocculant at elevated temperature and a dispersant at room temperature enables both rapid sedimentation and increased sediment density in batch solid/liquid separations. In addition, a pilot scale thickener operated in continuous flow has demonstrated that the underflow suspension rheology can be dramatically decreased resulting in reduced pumping costs.