Nacre‐Inspired Graphene/Metal Hybrid by In Situ Cementation Reaction and Joule Heating

Abstract

A nacre mimicking layered composite consisting of multilayer graphene (MLG) flakes and copper is fabricated in this study by a two‐step process including cementation reaction and Joule heating via spark plasma sintering (SPS). In situ cementation reaction deposits copper nanodroplets on activated graphene flakes with the aid of reducer Magnesium metal. The copper‐coated graphene flakes are subjected to pressure and localized Joule heating, resulting in a hierarchical 3D architecture comprising of uniformly aligned graphene flakes firmly bonded together by intermediate copper layers. The lamellar microstructure is characterized by a heterogeneous variation of elastic modulus. The impact of this hierarchical structure on the composite's mechanical behavior is explored by indentation loading, revealing a four‐fold increase in the load bearing ability of MLG/Cu hybrid as compared to MLG monolith. The Nacre‐inspired MLG‐Cu hybrid exhibits work of indentation ≈22.4 mJ, which is 500% improvement over MLG monolith (≈3.7 mJ). Copper deposition on graphene significantly improves the inter‐layer adhesion and restricts the sliding, pull‐out, and delamination of graphene flakes. The intimate interfacial contact between the constituent layers of the 3D hybrid facilitates effective stress‐transfer, thereby improving the overall load‐bearing ability. The novel processing route proposed here can be applied to other 2D materials for developing bioinspired 3D architectures with superior mechanical properties for a wide range of applications.

Synergistic Effect of Spark Plasma Sintering Driven Solid-Solution Phases on Scratch Resistance in Two-Dimensional Materials

“…Changing the SPS processing parameters has also been shown to affect the tribological behavior of NiTi alloys attributed to the phase transformation [30,31]. SPS has widely been used to obtain bulk 2D materials and their composites [32][33][34][35][36]. It is yet to be studied if rapid changes in the processing environment bring about the formation of new phases or changes in mechanical properties concerning the original 2D materials used.…”

Bioinspired Design of Graphene‐Based Materials

“…For example, a structure made up of multi-layer graphene platelet "bricks" with sintered copper nanoparticle "mortar" showed improved inter-layer adhesion and restricted the sliding, pull-out, and delamination of graphene flakes, reaching a 500% improvement in the work of indentation if compared to pristine graphene flakes without any binder. [130] Improved mechanical properties are not the only structurerelated enhancement in a graphene-based nacre-like material. The inter-nanosheet spacing along both the transverse and longitudinal axes leads to a certain degree of porosity, much like a natural cell membrane.…”

Interface Engineering and Direct Observation of Strengthening Behavior in Field‐Sintered Boron Nitride Nanotube–Magnesium Alloy Composite

“…High pressure and local electric discharge (between the powders and the nanotubes) during SPS can promote rapid physical/chemical bonding. [26,27] The vacuum environment of SPS is also conducive to prevent hightemperature oxidation of AZ31. BNNT in the form of a porous mat (%80% porosity) consisting of fine (%10 nm in diameter) and long (up to 100 μm) nanotubes (BNNT, LLC, Newport News, VA, USA) was used in the composite.…”

“…Spark plasma sintering (SPS) process was used for pressure, and direct current (DC)‐assisted consolidation (Figure ). High pressure and local electric discharge (between the powders and the nanotubes) during SPS can promote rapid physical/chemical bonding . The vacuum environment of SPS is also conducive to prevent high‐temperature oxidation of AZ31.…”