Influence of the Fine Fraction and Sintering on Selected Isotropic and Anisotropic Bulk Properties of Uniaxial Compacts

This study focuses on the influences of the fine particle fraction and the minimum particle size on the density, the shrinkage, the Young's modulus E, and the anisotropies of shrinkage and E. A lower minimum particle size and a higher fines content improved the particle packing, lubrication and sintering densification resulting in higher densities and E. Presumably due to a lower-density neutral zone after pressing, the anisotropic shrinkage was higher in the pressing direction, improving the density homogeneity. For the Young's modulus, the extent of the anisotropy increased mainly with a higher sintering capability (high fines content). Especially the core as a part of the neutral zone had a lower E. Exemplary density and open porosity distributions revealed that flaws formed in the core, which led to the lower E. The pressure distribution during uniaxial pressing leads to a density distribution and, finally, to a flaw density or flaw size distribution after sintering.