Chapter 4 Fabrication of Porous and Dense Ceramics from Transitional Nano-Alumina

摘要

Porous alumina ceramics (density 0.75 TD) with a typical vermicular microstructure were obtained from transitional nano-alumina powder by cold isostatic pressing (P = 500 MPa) and sintering at non-isothermal conditions from RT to 1,500℃. Mechanical activation, realized by attriting, was used to reduce the α-Al_2O_3 transformation to a temperature of 1,038℃. Conventional pressing (P = 500 MPa) and sintering at 1,500℃ were used to fabricate 0.96 TD dense alumina ceramics. Electrophoretic deposition was applied to the mechanically activated powder followed by isostatic pressing and sintering. Compacts with a density of 0.94 TD were obtained at 1,400℃/30 min. The microstructure was homogenous with grain sizes of 300 ± 100 nm.