ABSTRACT
Specifi c surface area S w (m 2 /kg) of a powder is one of the basic properties of the powder and is generally
represented by the surface area of total particles contained in a unit mass of powder. This value implies the internal and external surfaces which can be measured using various probes, such as gases and liquids. In the case of adsorption methods, adsorptive gas as a probe molecule must be accessible to all of the surfaces in cavities, cracks, and micropores. Nowadays, powders used as raw materials and intermediate manufactured goods have become more important, and industrial needs concerning particle size, particle shape, purity and uniformity, of powders have become more stringent. For example, for fi ne powders, purity and uniformity are necessary for manufacturing of precision materials such as electronics and fi ne ceramics. When the particle size decreases markedly, powdery phenomena depend largely on surface properties. Therefore, characterization of the powder surface becomes increasingly signifi cant with a decrease in the diameter of powder particles.
