Load Propagation Mechanisms Analyzed by Granule Deformation in Semi-Dry Pressed Bodies
Masato Sato, Tatuaki Nakano and Haruhisa Shiomi
Abstract:Load propagation mechanisms in semi-dry pressed bodies of granules with 12 mass% water content were discussed comparing with those in dry pressed bodies of spray-dried granules. The deformation behavior of granules was investigated under a uniaxial loading condition by a computer assisted image analysis in order to analyze the load propagation mechanisms. It was found that the use of granules with 12 mass% water content was effective to obtain densely compacted bodies because they had higher granular density and strength. In the primary stage of semi-dry pressing,the rearrangement of granules mainly occurred,and thus the load was scarcely propagated. On the other hand, the deformation of granules was predominant in the middle stage of the process, and the load propagation occurred through piller-like structures formed from the top to the bottom of the compacts. Furthermore, in the last stage, the load was propagated due to the fracture of granules without rearrangement. Also, as compaction proceeded, water in granules was moved to surface or interguranules, and improved lubricating ability between granules and/or between granules and a wall of die. Key Words:ceramics, powder pressing, moisture granule, plastic forming, image analysis