Facility for preparation of advanced metallic and ceramic materials

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While advanced ceramics and their composites have been prepared from powders for many decades, there is now a growing interest in producing metallic components from powder sources. This approach offers the benefit of near-net shape production and reduced material wastage, when compared to more conventional metal forming routes such as casting. The processing of advanced particulate materials requires that the powders are initially consolidated into the desired shape, prior to final densification by sintering. Occasionally this can be achieved through simple uniaxial compression, especially for selected metallic alloys such as aluminium and steels (using pressures up to 600 MPa), and when the particle sizes are moderately coarse (i.e. > 40 microns). However, for metals such as magnesium and titanium, which can deform by twinning, die binding becomes a serious problem even at moderate uniaxial pressures (i.e. > 100 MPa). In addition, the use of fine metallic powders (i.e. < 20 microns) is simply not feasible, even though such powders would have potentially greater 'sinterability'. Similarly, for micron or sub-micron sized ceramic powders it is generally necessary to use high pressure isostatic compaction. Uniaxially pressed ceramic preforms do not have sufficient green strength or density, as they invariably cannot be pressed at pressures above ~50 MPa, as die binding and wear can arise. These problems can be alleviated by cold isostatic pressing (CIP), especially when following low pressure uniaxial pressing. The present proposal requests the provision of funding for a CIP system, capable of pressures up to 689 MPa, which will be used for alloys based on aluminium, magnesium, nickel and titanium, as well as for advanced structural ceramics, such as silicon nitride and titanium carbide. The CIP will allow production of novel, ceramic-reinforced metal matrix composites, where fine particle sizes can be used to promote microstructural homogeneity. An atmosphere controlled glove-box is also available, so that more reactive metal powders can be pressed without exposure to an oxidising atmosphere, which is a major problem for finer particle sizes. Finally, precision CNC milling facilities are available for further shaping of CIPed preforms.