MANUFACTURE OF POWDER COMPACTS

The quality of a powder compact depends on the uniformity of the particle size distribution throughout its volume and the retaining of a refined microstructure during the final consolidation process. This paper deals with the creation of uniform green compacts from powders and the dynamic consolidation process. An overview of basic issues and problems concerning the behaviour and handling of granular materials is presented, emphasising recent results on particle size segregation induced through vibrations and occurring in granular flows. The implications of segregation on the production of green compacts are introduced followed by a discussion of their formation via ultrasonic vibrations. The dynamic (shock) consolidation process of form dense compacts with metastable or refined microstructures from green compacts is described. A critical review and discussion of the kinetics and energetics in the shock consolidation process, including particle bonding and shock energy distribution, is presented.