A Compaction Method to Make Uniformly Dense Ceramic Bodies of Complex Shape

Abstract

A method of uniaxial dry compacting homogeneously dense powdered bodies of complex shape without macroscopic defects has been developed. It is based on the self-alignment of uniform density regions within a green compact by controlling pressing forces to minimize die-wall friction effects. An equation is proposed that defines the density differential throughout the height of a green compact, which depends on geometrical parameters, and requires the controlled movement of die parts. This method decreases density gradients in complex shape bodies. It was applied to manufacture ceramic articles from nanopowder like impellers and plates with longitudinal holes.

The comparison of model compaction method to make uniformly dense ceramic bodies

“…of the passive shaping surface will be uniform. From the theory of compacting powders in closed molds [7], due to die-wall friction, the density differential Δρ through the height of the compact along axis [EeE′] will be always less than that near the walls (along line [AaA′]), while the average density value <ρ> along any vertical line will be uniform at any instant during pressing [14]:…”