Novel Bamboo-Like Fibrous, Micro-Channeled and Functional Gradient Microstructure Control of Ceramics

Abstract

In this paper development of novel ceramic microstructures by the fibrous monolithic process were reported. Attempts were made to tailor the microstructures of these advanced ceramics by introducing fibrous or layered morphology to incorporate multi-toughening mechanisms. Fabrication and characterization of four different kinds of microstructure, termed in this manuscript as network type, double network type, functional gradient microchanneled and functional gradient microchanneled double network type microstructure, were reported. In network and double network type microstructure developments the two phase Al₂O₃-(m-ZrO₂) cores were embedded within network-type frames of t-ZrO₂ single phase. In the double network type microstructure, an additional thicker network-type t-ZrO₂ enclosure surrounded a network-type micro-assembly. Unidirectionally aligned continuously porous HAp-Al₂O₃-ZrO₂ tri-phase ceramic composites were fabricated by the same method to incorporated functional gradient for improved functionality and depress processing defects. The microstructure had three layers of HAp/HAp-(Al₂O₃-(m-ZrO₂))/Al₂O₃-(t-ZrO₂) around the continuous pore with compositional gradient. In the functionally gradient micro-channeled HAp/HAp-(Al₂O₃-(m-ZrO₂))/Al₂O₃-(t-ZrO₂) composites, the size and distribution of micro-channels were homogeneously controlled. Detailed morphological analyses of the resulting microstructures were studied.