Evaluation of Compaction Characteristics of Powder by Uniaxial Pressing Test in a Cylindrical Die

摘要

Ceramic components and powder metallurgy parts are commonly produced by forming dense compacts of granulated powders for subsequent firing. It is important to know the compaction characteristics of granulated powders for designing the compaction processes. Those characteristics also give us insight into the granulation process and influence the properties of final fired products. We developed a uniaxial pressing test as a simple and practical method to evaluate the compaction characteristics of powders, and improved the accuracy of the measurement of both axial and lateral stresses. By assuming an associated flow law, we could evaluate a yield function that included both the first and second stress invariants. Furthermore, we could evaluate apparent elastic coefficients in the same uniaxial pressing test by measuring elastic recovery when compaction pressure was unloaded. The test was applied to a granulated powder of Al_2O_3-C for evaluating the yield function and elastic coefficients of its compact.