Manufacturing and Mechanical Assessment of Alumina/Epoxy Composites Inspired by The Structure of Nacre

Abstract

Abalone Nacre (Mother-of-pearl) is one of the natural material known for its distinctive blend of high strength and toughness. This distinct amalgamation is credited to its intricate microstructural hierarchy, featuring a brick-and-mortar arrangement that extends across nano to macro scales. The current research focuses on producing and evaluating mechanical properties of alumina/epoxy composites by drawing inspiration from the characteristic structural attributes of natural nacre. A unique approach of combining unidirectional freezecasting, consolidation, and infiltration was utilized to fabricate nacre-mimetic inorganic/organic composite. Ceramic preforms were first manufactured by freeze-casting of ceramic suspension containing α-alumina platelets. The level-1 hierarchy, i.e. emulating the inorganic phase of nacre, was established by uniaxial pressing (perpendicular to the freezing direction) of large aligned porous freeze-cast green alumina scaffolds, followed by sintering at 1500°C/4 h. The second level of hierarchy was achieved by infiltrating epoxy into the aligned brick (i.e. alumina platelets) layers under high vacuum conditions. Flexural and SENB tests revealed exceptional mechanical properties, showing a maximum flexural strength of 320 MPa and a fracture toughness of 6 MPa√m. This research offers crucial insights into optimization of compositions of bioinspired inorganic/organic composites (in bulk) for superior mechanical performance, offering potential applications in diverse engineering domains.