Phenomena at the powder-wall boundary during die compaction of a fine oxide powder

Fine powders (particle size smaller than 0.1 μm) are often used for the fabrication of modern fine-grained ceramics. During die compaction of such fine powders, special phenomena at the powder-wall boundary can be expected because the size of the particles is of the same order as the size of the wall asperities. In the present paper, the principles of powder mechanics are applied to experimental results obtained with a fine ferric oxide powder. The appearance of a dense boundary layer on the surface of compacts could be related to the occurrence of powder failure during compaction at the die wall.