Bioinspired Nacre-Like Alumina with a Metallic Nickel Compliant Phase Fabricated by Spark-Plasma Sintering

Small. 2019 Aug;15(31):e1900573. doi: 10.1002/smll.201900573. Epub 2019 May 27.

Abstract

Many natural materials present an ideal "recipe" for the development of future damage-tolerant lightweight structural materials. One notable example is the brick-and-mortar structure of nacre, found in mollusk shells, which produces high-toughness, bioinspired ceramics using polymeric mortars as a compliant phase. Theoretical modeling has predicted that use of metallic mortars could lead to even higher damage-tolerance in these materials, although it is difficult to melt-infiltrate metals into ceramic scaffolds as they cannot readily wet ceramics. To avoid this problem, an alternative ("bottom-up") approach to synthesize "nacre-like" ceramics containing a small fraction of nickel mortar is developed. These materials are fabricated using nickel-coated alumina platelets that are aligned using slip-casting and rapidly sintered using spark-plasma sintering. Dewetting of the nickel mortar during sintering is prevented by using NiO-coated as well as Ni-coated platelets. As a result, a "nacre-like" alumina ceramic displaying a resistance-curve toughness up to ≈16 MPa m½ with a flexural strength of ≈300 MPa is produced.

Keywords: bioinspired ceramics; ceramic-metal composites; compliant-phase ceramics; flexural strength; fracture toughness; nacre; spark plasma sintering.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.