Microstructure Control of Al<SUB>2</SUB>O<SUB>3</SUB>/ZrO<SUB>2</SUB> Composite by Fibrous Monolithic Process

Abstract

Homogeneously tailored Al 2 O 3 -ZrO 2 composites were fabricated using a fibrous monolithic process. The microstructure of the composites was varied depending on the area reduction ratio, and correlated well with calculated data. The sintered bodies presented a continuously fibrous monolithic microstructure and no swelling occurred during the binder burning-out. Microcracks were observed at the Al 2 O 3 -ZrO 2 interfaces, due to the mismatch of thermal expansion coefficients between Al 2 O 3 and ZrO 2 phases. Most of the ZrO 2 grains included twin defects to accommodate the stress field during the sintering process.

Relationship Between Microstructures and Material Properties of Novel Fibrous Al2O3–(m‐ZrO2)/t‐ZrO2 Composites

“…However, in the fifth passed fibrous Al 2 O 3 –(m‐ZrO 2 )/t‐ZrO 2 composite, its fracture strength as well as fracture toughness had improved to high values. The values were remarkable compared with those of the fibrous Al 2 O 3 /m‐ZrO 2 composite ( K I C =10 Mpa·m 1/2 , bending strength=258 MPa) 19 . The main reason for the excellent mechanical properties is because of the dense fibrous microstructure and the introduction of multi‐toughening mechanisms; i.e., (1) the crack bridging by the fibrous microstructure, (2) the microcracking by the mismatch of thermal expansion coefficients between the Al 2 O 3 and the m‐ZrO 2 phase, and (3) the phase transformation toughening of t‐ZrO 2 .…”

“…One typical example is the layered Si 3 N 4 /BN composite, 18 and it shows remarkable improvement of fracture toughness because of the crack deflection. Also, in the fibrous Al 2 O 3 /m‐ZrO 2 composites, 19 the fracture strength decreased remarkably, although the fracture toughness had increased by the microcracking and crack‐bridging mechanisms. In the previous work, 20 although Al 2 O 3 –(m‐ZrO 2 )/t‐ZrO 2 composites having a fibrous and homogeneous microstructure were obtained, their mechanical properties had not remarkably improved because of the weakness of fracture‐toughening mechanisms such as crack bridging and crack deflection.…”

Effect of the volume ratio of zirconia and alumina on the mechanical properties of fibrous zirconia/alumina bi-phase composites prepared by co-extrusion

“…[3][4][5][6][7] In the case of fibrous composites, there are some * Corresponding author. reports on the microstructure of the fibrous composites with a rigid interface, [8][9][10][11][12][13][14] but the evaluation of their mechanical properties is limited. [8][9][10][11] In our previous reports, the feasibility of forming fine-scale fibrous microstructures was demonstrated for alumina/zirconia composites with a rigid interface, by using a repeated coextrusion process through a reduction die.…”

Fabrication of continuously porous SiC–Si3N4 composite using SiC powder by extrusion process

“…High fracture-toughened ceramic composites and high strength continuously porous ceramics can be fabricated using the extrusion process. [9][10][11][12][13] This process well control the fibrous microstructure of SiC ceramics by increasing the number of extrusion passes.…”