Abstract
Densed Al_2O_3-based composites with BaTiO_3 particulates were fabricated by spark plasma sintering (SPS). The relative density and microstructure (grain size, phase) of composites were compared with those obtained by conventional pressureless sintering (PLS). BaTiO_3-Al_2O_3 composites could be rapidly densified using SPS process under sintering temperatures between 1000 and 1500℃, at a heating rate of around 100℃/min, with a short holding time (1-3min). The relative density of BaTiO_3Al_2O_3 composites was decreased with the increasing BaTiO_3 content. In addition, there were reaction phases between Al_2O_3 matrix and dispersed BaTiO_3 particulates at sintering temperatures above 1100℃ in SPS process. Higher density of BaTiO_3-Al_2O_3 with various compositions could be achieved at lower sintering temperatures by SPS compared with that by PLS. However, full densification was prevented by the onset of abnormal grain growth in BaTiO_3-Al_2O_3 composites sintered by SPS at 1300℃. The microstructure and fracture toughness were also studied in this work.
