Microstructures and Mechanical Properties of Fine-Scale Fibrous Alumina / Zirconia Bi-Phase Composite Fabricated by Co-Extrusion Process
A bundle of feedrod composed of ordinary arranged alumina and zirconia green rods was co-extruded through a 6:1 reduction die. The volume fraction of zirconia phase was varied from 10 to 88 vol%. After the first co-extrusion, the individual pieces were bundled and co-extruded again, reducing the lateral size of each phase and multiplying the number of continuous monofilaments. After a 3rd extrusion step and sintering at 1600oC, crack-free composites with a fiber diameter of ~50 μm were obtained for all compositions. The fracture toughness of the composites was improved by introducing fine second phase filaments into the matrix. The maximum fracture toughness of 6.2 MPam1/2 was attained in the 3rd co-extruded composite which consisted of 53 vol% alumina and 47 vol% zirconia. Bending strength of the composites was almost the same as that of the monolithic alumina regardless of the composition.
T. Ohji, T. Sekino and K. Niihara
H. Miyazaki et al., "Microstructures and Mechanical Properties of Fine-Scale Fibrous Alumina / Zirconia Bi-Phase Composite Fabricated by Co-Extrusion Process", Key Engineering Materials, Vols. 317-318, pp. 619-622, 2006