Physics of Radio-Frequency Plasmas,by Pascal Chabert and Nicholas Braithwaite

The mechanism whereby powders may be compressed to form solid objects is not properly understood, largely because, until recently, the process has not been studied by sufficiently powerful techniques. This paper describes a number of techniques developed for a detailed study of powder compaction. Methods for measuring specific surface areas of powders and powder compacts, and hence the areas of contact between the particles, are discussed and reasons for selecting an adsorption method are explained. A gas adsorption apparatus capable of determining very small specific surface areas is described, as is the use of the scanning electron microscope. Both techniques were used to investigate particle fracture during compaction. In addition the study of pore size gives valuable insight into the movement of particle fragments once they have been produced. The use of mercury porosimetry in this connection is described.