17.1: Introduction

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Handling and processing of powders is central to many areas of science and technology. Most ceramic materials can only be formed via powder processing, but powder metallurgy is also an important branch of materials science and polymers are frequently handled as (coarse) particles. Powder processing is also pivotal in many other industrial sectors, such as food, pharmaceuticals, agriculture, mining etc. Moreover, an understanding of the behaviour of assemblies of solid particles in fluids is essential in areas as diverse as filtration of Diesel exhaust and avoiding explosions in flour mills. Particle sizes of interest vary from a few nm to several mm (although most technological activity is focussed on the range from 100 nm to 100 microns).

Important background includes the factors affecting the dynamics of solid particles suspended in fluids and the flow of fluids through porous mdia (including filters). This TLP provides an introduction to the equations and dimensionless numbers that control these effects, with simulations that allow the behaviour to be explored in particular cases. There are also sections dealing with measurement of particle size and the procedures involved in consolidation of powder particles into solid articles, via various types of sintering process, and the creation of surface coatings via thermal spraying of particles.