Twisted-layer boron nitride ceramic with high deformability and strength

Abstract

Moiré superlattices formed by twisted stacking in van der Waals materials have emerged as a new platform for exploring the physics of strongly correlated materials and other emergent phenomena1–5. However, there remains a lack of research on the mechanical properties of twisted-layer van der Waals materials, owing to a lack of suitable strategies for making three-dimensional bulk materials. Here we report the successful synthesis of a polycrystalline boron nitride bulk ceramic with high room-temperature deformability and strength. This ceramic, synthesized from an onion-like boron nitride nanoprecursor with conventional spark plasma sintering and hot-pressing sintering, consists of interlocked laminated nanoplates in which parallel laminae are stacked with varying twist angles. The compressive strain of this bulk ceramic can reach 14% before fracture, about one order of magnitude higher compared with traditional ceramics (less than 1% in general), whereas the compressive strength is about six times that of ordinary hexagonal boron nitride layered ceramics. The exceptional mechanical properties are due to a combination of the elevated intrinsic deformability of the twisted layering in the nanoplates and the three-dimensional interlocked architecture that restricts deformation from propagating across individual nanoplates. The advent of this twisted-layer boron nitride bulk ceramic opens a gate to the fabrication of highly deformable bulk ceramics.

Recycling Functional Fillers from Waste Tires for Tailored Polystyrene Composites: Mechanical, Fire Retarding, Electromagnetic Field Shielding, and Acoustic Insulation Properties—A Short Review

“…Inspired by the low-friction properties of carbon black/polydimethylsiloxane composite cable materials, recycled carbon black is also an ideal lubricant material. The development of sustainable tribology in elastomer sealants, cables, or bearing materials for applications in extreme environmental conditions has attracted attention via combined low- or high-temperature tribometers with in situ or ex situ synchrotron small-angle X-ray scattering and aberration-corrected transmission electron microscope equipment (Argonne National Laboratory, Lemont, IL, USA and Brookhaven National Laboratory, Long Island, NY, USA) [ 4 , 92 , 93 , 94 ]. These materials primarily serve the US military (fighter aircraft or aircraft carriers), US National Aeronautics and Space Administration, or Space Exploration Technologies Corporation, SpaceX (Hawthorne, CA, USA).…”

Borrowed dislocations for ductility in ceramics

“…Ceramics exhibit attractive properties for a range of applications, including high hardness, high strength, excellent corrosion resistance, and a notable tolerance to high temperatures. These properties make ceramics useful across diverse fields such as aerospace and automotive engineering, energy storage, electronics, and semiconductors ( 1 – 8 ). However, ceramics are intrinsically brittle at ambient temperatures because of strong chemical bonds, which lead to a high threshold stress required for dislocation nucleation and impede the initiation of dislocations ( 9 – 14 ).…”

“…Therefore, the high threshold stress for dislocation nucleation in ceramics substantially limits the potential for improving plasticity through a dislocation-engineering strategy ( 16 – 18 ). As a result, several strategies have been directed toward achieving better plasticity in ceramics through alternative mechanisms ( 8 , 9 , 19 – 23 ). In our previous work, for instance, we improved the compressive plasticity of silicon nitride ceramic through bond switching at coherent interfaces ( 20 ).…”