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Please use this identifier to cite or link to this item: http://hdl.handle.net/1860/99

Title: Cyclic compaction of soft-hard powder mixtures
Authors: Trivic, Nikola
Keywords: Compacting;Powder metallurgy;Relative density;Materials engineering
Issue Date: 4-Apr-2003
Abstract: Cyclic compaction of powder mixtures has been shown to be more effective compared to “classic” static compaction. The goal of this work was to understand cyclic compaction and identify the origin of the improved compressibility of brittle powders and their composites. In particular, we tried to detect systematic effects of particle size, and wall friction on green density and strength of composite powder mixtures. In this thesis we will discuss: a) a review of the existing literature, b) a set of experimental data obtained with mixtures of lead and alumina as model material system, and c) numerical simulations of this problem. Our experimental results confirm the trends seen previously, in terms of higher relative density and strength for cyclic compaction. Although there are differences in the efficiency of dynamic compaction for different size ratios of hard and soft phase, the trend is not monotonic. Trends with respect to friction were not easily detected due to the scatter in the results. Numerical modeling of this problem shows that inhomogeneity in the residual in- die stress field in combination with favorable material properties after unloading, is responsible for lower yielding upon unloading. The higher the inhomogeneity in density and in- die residual stress field, the higher the effectiveness of cyclic compaction.
URI: http://dspace.library.drexel.edu/handle/1860/99
Appears in Collections:Drexel Theses and Dissertations

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