Microstructures and Mechanical Properties of Fine-Scale Fibrous Alumina/Zirconia Bi-Phase Composite Fabricated by Co-Extrusion Process

摘要

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 percent . 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 3~(rd) extrusion step and sintering at 1600 deg C, crack-free composites with a fiber diameter of approx 50 mu m 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 MPa centre dot m~(1/2) was attained in the 3~(rd) co-extruded composite which consisted of 53 vol percent alumina and 47 vol percent zirconia. Bending strength of the composites was almost the same as that of the monolithic alumina regardless of the composition.