Bio-inspired damage-tolerant alumina-based layered ceramics through rapid sintering

Abstract

Layered ceramics have proved effective under contact damage or thermal shock, associated with the effect of compressive residual stresses and/or textured microstructure against surface crack propagation. In addition, the use of nonconventional sintering techniques, including rapid sintering, has demonstrated the feasibility of tailoring the size and/or shape of grains in bulk alumina materials. In this study, we explore the feasibility of rapid sintering alumina-based layered ceramics to enhance their damage tolerance, combining in-plane residual stresses and tailored microstructures in the different layers. Templated alumina layers embedded within a fine-grained alumina matrix are sintered using a pressureless spark plasma sintering (SPS) setup. The microstructure evolution of the individual layer regions is investigated under different sintering conditions. An optimal combination of highly textured internal layers with sharp interfaces and fine-grained alumina is found for heating rates of 100°C min−1, maximum sintering temperature of 1600°C, and 30 min dwell time. Hertzian contact and thermal shock experiments performed in selected rapid sintered samples show crack arrest and crack deflection in the textured layers, as found in conventionally sintered bio-inspired alumina ceramics. The successful rapid sintering of alumina-based multi-materials opens the path for further improvement in terms of reliability and damage tolerance in ceramic components.