Mechanical properties of graphene platelet-reinforced alumina ceramic composites
TL;DR: In this paper, the effects of GPLs on the microstructure and mechanical properties of the Al 2 O 3 based ceramic composites were investigated, and the results show that GPLs are well dispersed in the ceramic matrix.
About: This article is published in Ceramics International.The article was published on 2013-08-01. It has received 312 citations till now. The article focuses on the topics: Ceramic & Ceramic matrix composite.
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TL;DR: In this paper, a bio-inspired approach based on widespread ceramic processing techniques for the fabrication of bulk ceramics without a ductile phase and with a unique combination of high strength (470 MPa), high toughness (17.3 MPa m1/2), and high stiffness (290 GPa).
Abstract: High strength and high toughness are usually mutually exclusive in engineering materials. In ceramics, improving toughness usually relies on the introduction of a metallic or polymeric ductile phase, but this decreases the material’s strength and stiffness as well as its high-temperature stability. Although natural materials that are both strong and tough rely on a combination of mechanisms operating at different length scales, the relevant structures have been extremely difficult to replicate. Here, we report a bioinspired approach based on widespread ceramic processing techniques for the fabrication of bulk ceramics without a ductile phase and with a unique combination of high strength (470 MPa), high toughness (17.3 MPa m1/2), and high stiffness (290 GPa). Because only mineral constituents are needed, these ceramics retain their mechanical properties at high temperatures (600 °C). Our bioinspired, material-independent approach should find uses in the design and processing of materials for structural, transportation and energy-related applications. The toughness of ceramic materials can be improved by introducing a polymeric or metallic ductile phase, yet most often this is at the expense of strength, stiffness and high-temperature stability. Now, a simple processing route based on widespread ceramic processing techniques is shown to produce bulk ceramics that mimic the structure of natural nacre and have a unique combination of high strength, toughness and stiffness, even at high temperatures.
687 citations
TL;DR: A bioinspired approach based on widespread ceramic processing techniques for the fabrication of bulk ceramics without a ductile phase and with a unique combination of high strength, high toughness, and high stiffness is reported.
Abstract: High strength and high toughness are usually mutually exclusive in engineering materials. Improving the toughness of strong but brittle materials like ceramics thus relies on the introduction of a metallic or polymeric ductile phase to dissipate energy, which conversely decreases the strength, stiffness, and the ability to operate at high temperature. In many natural materials, toughness is achieved through a combination of multiple mechanisms operating at different length scales but such structures have been extremely difficult to replicate. Building upon such biological structures, we demonstrate a simple approach that yields bulk ceramics characterized by a unique combination of high strength (470 MPa), high toughness (22 MPa.m1/2), and high stiffness (290 GPa) without the assistance of a ductile phase. Because only mineral constituents were used, this material retains its mechanical properties at high temperature (600{\deg}C). The bioinspired, material-independent design presented here is a specific but relevant example of a strong, tough, and stiff material, in great need for structural, transportations, and energy-related applications.
589 citations
TL;DR: In this paper, the authors focus on the following topics: (1) materials requirements in design of aircraft structures and engines, (2) recent advances in the development of aerospace materials, (3) challenges faced by recent aerospace materials and (4) future trends in aerospace materials.
477 citations
TL;DR: The use of graphene as reinforcement for structural materials is motivated by their exceptional mechanical/functional properties and their unique physical/chemical characteristics as discussed by the authors. But this review focuses on MMCs and CMCs because of their technological importance for structural applications and the unique challenges associated with developing high-temperature composites with nanoparticle reinforcements.
Abstract: This review critically examines the current state of graphene reinforced metal (GNP-MMC) and ceramic matrix composites (GNP-CMC) The use of graphene as reinforcement for structural materials is motivated by their exceptional mechanical/functional properties and their unique physical/chemical characteristics This review focuses on MMCs and CMCs because of their technological importance for structural applications and the unique challenges associated with developing high-temperature composites with nanoparticle reinforcements The review discusses processing techniques, effects of graphene on the mechanical behaviour of GNP-MMCs and GNP-CMCs, including early studies on the tribological performance of graphene-reinforced composites, where graphene has shown signs of serving as a protective and lubricious phase Additionally, the unique functional properties endowed by graphene to GNP-MMCs and GNP-CMCs, such as enhanced thermal/electrical conductivity, improved oxidation resistance, and excellent bi
456 citations
TL;DR: In this article, the buckling and postbuckling behaviors of functionally graded multilayer nanocomposite beams reinforced with a low content of graphene platelets (GPLs) resting on an elastic foundation were investigated.
358 citations
Cites background from "Mechanical properties of graphene p..."
...[14] studied the mechanical properties of alumina ceramic composites reinforced with GPLs and suggested that the flexural strength of composites are considerably higher than that of monolithic ceramic samples....
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References
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NEC1
TL;DR: Iijima et al. as mentioned in this paper reported the preparation of a new type of finite carbon structure consisting of needle-like tubes, which were produced using an arc-discharge evaporation method similar to that used for fullerene synthesis.
Abstract: THE synthesis of molecular carbon structures in the form of C60 and other fullerenes1 has stimulated intense interest in the structures accessible to graphitic carbon sheets. Here I report the preparation of a new type of finite carbon structure consisting of needle-like tubes. Produced using an arc-discharge evaporation method similar to that used for fullerene synthesis, the needles grow at the negative end of the electrode used for the arc discharge. Electron microscopy reveals that each needle comprises coaxial tubes of graphitic sheets, ranging in number from 2 up to about 50. On each tube the carbon-atom hexagons are arranged in a helical fashion about the needle axis. The helical pitch varies from needle to needle and from tube to tube within a single needle. It appears that this helical structure may aid the growth process. The formation of these needles, ranging from a few to a few tens of nanometres in diameter, suggests that engineering of carbon structures should be possible on scales considerably greater than those relevant to the fullerenes. On 7 November 1991, Sumio Iijima announced in Nature the preparation of nanometre-size, needle-like tubes of carbon — now familiar as 'nanotubes'. Used in microelectronic circuitry and microscopy, and as a tool to test quantum mechanics and model biological systems, nanotubes seem to have unlimited potential.
39,086 citations
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TL;DR: Owing to its unusual electronic spectrum, graphene has led to the emergence of a new paradigm of 'relativistic' condensed-matter physics, where quantum relativistic phenomena can now be mimicked and tested in table-top experiments.
Abstract: Graphene is a rapidly rising star on the horizon of materials science and condensed-matter physics. This strictly two-dimensional material exhibits exceptionally high crystal and electronic quality, and, despite its short history, has already revealed a cornucopia of new physics and potential applications, which are briefly discussed here. Whereas one can be certain of the realness of applications only when commercial products appear, graphene no longer requires any further proof of its importance in terms of fundamental physics. Owing to its unusual electronic spectrum, graphene has led to the emergence of a new paradigm of 'relativistic' condensed-matter physics, where quantum relativistic phenomena, some of which are unobservable in high-energy physics, can now be mimicked and tested in table-top experiments. More generally, graphene represents a conceptually new class of materials that are only one atom thick, and, on this basis, offers new inroads into low-dimensional physics that has never ceased to surprise and continues to provide a fertile ground for applications.
35,293 citations
TL;DR: It is reported that homogeneous colloidal suspensions of chemically modified graphene sheets were readily produced in a wide variety of organic solvent systems and "paperlike" materials generated by very simple filtration of the reduced graphene oxide sheets had electrical conductivity values as high as 16,000 S/m.
Abstract: We report that homogeneous colloidal suspensions of chemically modified graphene sheets were readily produced in a wide variety of organic solvent systems. Two different sets of solubility parameters are used to rationalize when stable colloidal suspensions of graphene oxide sheets and, separately, of reduced graphene oxide sheets in a given solvent type are possible and when they are not. As an example of the utility of such colloidal suspensions, “paperlike” materials generated by very simple filtration of the reduced graphene oxide sheets had electrical conductivity values as high as 16 000 S/m.
1,541 citations
TL;DR: On-chip microwave measurements demonstrate that the self-aligned graphene transistors have a high intrinsic cut-off (transit) frequency of fT = 100–300 GHz, with the extrinsic fT largely limited by parasitic pad capacitance.
Abstract: Graphene has attracted considerable interest as a potential new electronic material. With its high carrier mobility, graphene is of particular interest for ultrahigh-speed radio-frequency electronics. However, conventional device fabrication processes cannot readily be applied to produce high-speed graphene transistors because they often introduce significant defects into the monolayer of carbon lattices and severely degrade the device performance. Here we report an approach to the fabrication of high-speed graphene transistors with a self-aligned nanowire gate to prevent such degradation. A Co(2)Si-Al(2)O(3) core-shell nanowire is used as the gate, with the source and drain electrodes defined through a self-alignment process and the channel length defined by the nanowire diameter. The physical assembly of the nanowire gate preserves the high carrier mobility in graphene, and the self-alignment process ensures that the edges of the source, drain and gate electrodes are automatically and precisely positioned so that no overlapping or significant gaps exist between these electrodes, thus minimizing access resistance. It therefore allows for transistor performance not previously possible. Graphene transistors with a channel length as low as 140 nm have been fabricated with the highest scaled on-current (3.32 mA μm(-1)) and transconductance (1.27 mS μm(-1)) reported so far. Significantly, on-chip microwave measurements demonstrate that the self-aligned devices have a high intrinsic cut-off (transit) frequency of f(T) = 100-300 GHz, with the extrinsic f(T) (in the range of a few gigahertz) largely limited by parasitic pad capacitance. The reported intrinsic f(T) of the graphene transistors is comparable to that of the very best high-electron-mobility transistors with similar gate lengths.
1,227 citations
TL;DR: Novel toughening mechanisms were observed that show GPL wrapping and anchoring themselves around individual ceramic grains to resist sheet pullout and the resulting cage-like graphene structures that encapsulate the individual grains were observed to deflect propagating cracks in not just two but three dimensions.
Abstract: The majority of work in graphene nanocomposites has focused on polymer matrices. Here we report for the first time the use of graphene to enhance the toughness of bulk silicon nitride ceramics. Ceramics are ideally suited for high-temperature applications but suffer from poor toughness. Our approach uses graphene platelets (GPL) that are homogeneously dispersed with silicon nitride particles and densified, at ∼1650 °C, using spark plasma sintering. The sintering parameters are selected to enable the GPL to survive the harsh processing environment, as confirmed by Raman spectroscopy. We find that the ceramic's fracture toughness increases by up to ∼235% (from ∼2.8 to ∼6.6 MPa·m(1/2)) at ∼1.5% GPL volume fraction. Most interestingly, novel toughening mechanisms were observed that show GPL wrapping and anchoring themselves around individual ceramic grains to resist sheet pullout. The resulting cage-like graphene structures that encapsulate the individual grains were observed to deflect propagating cracks in not just two but three dimensions.
575 citations