Densification behavior of dynamically shock compacted AI2O3/ZrO2 powders synthesized through rapid solidification

Abstract

The rapidly solidified alumina-zirconia eutectic contains high volume fractions of nanocrystallinet- ZrO2, which makes the material a promising precursor for the manufacturer of fracture-resistant ceramic specimens. Unfortunately, conventional powder processing and sintering techniques are inadequate for the fabrication of dense specimens using this material. We have used dynamic shock compaction to facilitate the achievement of high density specimens which retain the unique microstructure of the precursor material. In an attempt to quantify the dynamics of the microstructural evolution which occurs during the compaction process, we have investigated the effect of various particle size distributions on the densification behavior of the material during the shock compaction and postcompaction sintering cycles. The shock compaction process produced high densities (∼73 to 78 pct of single-crystal theoretical) by inducing a highly efficient packing of the particles. A bimodal powder distribution was also compacted and this specimen exhibited a relative density of 86.2 pct, approximately 10 pct higher that those of the unimodal compositions. In this compact, the small particles efficiently filled the interstices between the larger particles. The high density of the bimodal compact did not translate to a high sintered density, however.