Fabrication and Mechanical Properties of Lamellar Al₂O₃ Ceramics

Abstract

Lamellar Al₂O₃ ceramics were fabricated by the slip casting method, using two types of Al₂O₃ powders having different particle sizes and densification behavior between each other. The lamellar ceramics have the structure of alternating dense and porous layers with respective thickness, λ_D and λ_P, ranging from 60 to 500μm, and the volume fraction of the dense layers, V_D, from 0 to 100%. The lamellar structures were controlled by changing the casting time and using the centrifugal force for draining the Al₂O₃ slurries during green forming. Fracture strengths of the lamellar ceramics were measured by three-point bending. Some of the lamellar ceramics showed higher flexural strength than monolithic, dense Al₂O₃ (-335MPa). The maximum strength, -400MPa, was obtained for the lamellar ceramic with V_D=89±3%, λ_D=500μm, λ_P=60μm. The high strength is discussed from the view point of the crack deflection in the porous layers.