Co-Axially Laminated Continuously Porous Composites in Al<SUB>2</SUB>O<SUB>3</SUB>-(m-ZrO<SUB>2</SUB>)/t-ZrO<SUB>2</SUB> System for High Mechanical Strength

Abstract

A micro-channeled composite with a laminated microstructure was fabricated in Al 2 O 3 -ZrO 2 composite system through a multipass extrusion process. Using this approach, Al 2 O 3 -(monoclinic-ZrO 2 )/tetragonal-ZrO 2 continuously porous composites with concentric laminates were fabricated. The entire matrix phase had a laminated microstructure of alternate lamina of Al 2 O 3 -(m-ZrO 2 ) and t-ZrO 2 with a homogeneous thickness and central channel. Each of the continuous channels was coaxially encircled by a group of 5 alternate laminates. The laminate plane was oriented along the axis of the continuous channels. The design strategy was to incorporate concentric lamellar microstructural units in a macro scaled ceramic body comprising a central channel for each. The frame modification was intended to improve the material properties of the channeled body which in turn could act as a porous space for the inclusion of additional functional attributes. Filaments of polymer mixed ceramic powders and pore forming agent carbon were stacked in a pre-designed arrangement to obtain the desired microstructure and then extruded to obtain green composites. The channel diameter and channel frame thickness were approximately 198 AE 10 mm and 158 AE 10 mm, respectively. The channel frame region was furnished with 9 alternating shells of Al 2 O 3 -(m-ZrO 2 ) and t-ZrO 2 with a thickness of around 10$20 mm. The material properties including the relative density and bending strength, which depend on temperature, were evaluated. The detailed microstructure of the channeled bodies was also characterized by Scanning Electron Microscope (SEM).