Effect of ball milling on graphene reinforced Al6061 composite fabricated by semi-solid sintering
TL;DR: In this paper, a 1.0-wt.% graphene reinforced aluminum 6061 (Al6061) composite was synthesized to investigate the effects of graphene dispersion by ball milling technique.
Abstract: A 1.0 wt.% graphene reinforced aluminum 6061 (Al6061) composite was synthesized to investigate the effects of graphene dispersion by ball milling technique. The Al6061 powder and graphene were ball milled at different milling times. The composites were then synthesized by hot compaction in the semi-solid regime of the Al6061. A three point bending test was performed to characterize the mechanical properties of the composite. The ball milled powder and the fracture surfaces of the composites were analyzed using the scanning electron microscopy. A maximum enhancement of 47% in flexural strength was observed when compared with the reference Al6061 processed at the same condition.
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TL;DR: In this paper, the authors focus on the recent development in mechanical and tribological behavior of self-lubricating metallic nanocomposites reinforced by carbonous nanomaterials such as CNT and graphene.
Abstract: Rapid innovation in nanotechnology in recent years enabled development of advanced metal matrix nanocomposites for structural engineering and functional devices. Carbonous materials, such as graphite, carbon nanotubes (CNT's), and graphene possess unique electrical, mechanical, and thermal properties. Owe to their lubricious nature, these carbonous materials have attracted researchers to synthesize lightweight self-lubricating metal matrix nanocomposites with superior mechanical and tribological properties for several applications in automotive and aerospace industries. This review focuses on the recent development in mechanical and tribological behavior of self-lubricating metallic nanocomposites reinforced by carbonous nanomaterials such as CNT and graphene. The review includes development of self-lubricating nanocomposites, related issues in their processing, their characterization, and investigation of their tribological behavior. The results reveal that adding CNT and graphene to metals decreases both coefficient of friction and wear rate as well as increases the tensile strength. The mechanisms involved for the improved mechanical and tribological behavior is discussed.
673 citations
Cites methods from "Effect of ball milling on graphene ..."
...[10] used graphite and exfoliated it to graphene in nitric acid and sodium chlorate solution....
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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
Cites background from "Effect of ball milling on graphene ..."
...tra of ball-milled composite powders [80,82,86] and FSP zone [103] exhibit no changes in GNP structure, however, an increase in defects occurs as the ID/IG ratio increases....
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...include mechanical alloying [80,82,88], hot extrusion [87,95], hot rolling [86], FSP [103] and other novel routes [85] (as discussed in the subsection on metallurgical processing techniques in the processing section)....
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TL;DR: The literature data supported that synthesis routes such as oxidative exfoliation-reduction, liquid-phase exfoliated and chemical vapor deposition have the potential to be commercialized due to their ability to produce large amount of high quality graphene.
Abstract: Graphene and its derivatives have gained significant attention of late due to their remarkable physicochemical properties. This review focuses firstly on the synthesis methods of graphene and its derivatives along with their attributes and characterization techniques. This is followed by a discussion of the potential industrial implementation of the synthesis routes. The potential industrial implementation of the graphene synthesis methods are reviewed using the key criteria of cost, process condition, yield, scalability, product quality and environmental impact. The literature data supported that synthesis routes such as oxidative exfoliation-reduction, liquid-phase exfoliation and chemical vapor deposition have the potential to be commercialized due to their ability to produce large amount of high quality graphene. Further development is necessary to overcome barriers such as environmental concerns and the high graphene cost.
280 citations
TL;DR: In this review, mechanical, thermal, and electrical properties of graphene reinforced epoxy nanocomposites will be correlated with the topographical features, morphology, weight fraction, dispersion state, and surface functionalization of graphene.
Abstract: Monolithic epoxy, because of its brittleness, cannot prevent crack propagation and is vulnerable to fracture. However, it is well established that when reinforced—especially by nano-fillers, such as metallic oxides, clays, carbon nanotubes, and other carbonaceous materials—its ability to withstand crack propagation is propitiously improved. Among various nano-fillers, graphene has recently been employed as reinforcement in epoxy to enhance the fracture related properties of the produced epoxy–graphene nanocomposites. In this review, mechanical, thermal, and electrical properties of graphene reinforced epoxy nanocomposites will be correlated with the topographical features, morphology, weight fraction, dispersion state, and surface functionalization of graphene. The factors in which contrasting results were reported in the literature are highlighted, such as the influence of graphene on the mechanical properties of epoxy nanocomposites. Furthermore, the challenges to achieving the desired performance of polymer nanocomposites are also suggested throughout the article.
241 citations
Cites result from "Effect of ball milling on graphene ..."
...[82] showed that fracture toughness was improved by increasing the graphene size, which is in negation with simulation results by Zhao and Hoa [120,121]....
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...As a result, fracture toughness and other mechanical properties—such as tensile and flexural strength and stiffness—start decreasing, which is in accordance with Zhao and Hoa’s simulation results [118]....
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...However, Chatterjee et al. [82] showed that fracture toughness was improved by increasing the graphene size, which is in negation with simulation results by Zhao and Hoa [120,121]....
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...Zhao and Hoa used a theoretical computer simulation approach to study the improvement in toughness when epoxy is reinforced with 2D nano-reinforcements of different particle size [118,119]....
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TL;DR: The RGrO-and-Cu artificial nacres exhibited simultaneous enhancement on yield strength and ductility as well as increased modulus, attributed to R GrO strengthening, effective crack deflection and a possible combined failure mode of RGr O.
Abstract: Metals can be strengthened by adding hard reinforcements, but such strategy usually compromises ductility and toughness. Natural nacre consists of hard and soft phases organized in a regular “brick-and-mortar” structure and exhibits a superior combination of mechanical strength and toughness, which is an attractive model for strengthening and toughening artificial composites, but such bioinspired metal matrix composite has yet to be made. Here we prepared nacre-like reduced graphene oxide (RGrO) reinforced Cu matrix composite based on a preform impregnation process, by which two-dimensional RGrO was used as “brick” and inserted into “□-and-mortar” ordered porous Cu preform (the symbol “□” means the absence of “brick”), followed by compacting. This process realized uniform dispersion and alignment of RGrO in Cu matrix simultaneously. The RGrO-and-Cu artificial nacres exhibited simultaneous enhancement on yield strength and ductility as well as increased modulus, attributed to RGrO strengthening, effective ...
220 citations
References
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TL;DR: In this paper, a model and theoretical understanding of the Raman spectra in disordered and amorphous carbon is given, and the nature of the G and D vibration modes in graphite is analyzed in terms of the resonant excitation of \ensuremath{\pi} states and the long-range polarizability of the long range bonding.
Abstract: The model and theoretical understanding of the Raman spectra in disordered and amorphous carbon are given. The nature of the G and D vibration modes in graphite is analyzed in terms of the resonant excitation of \ensuremath{\pi} states and the long-range polarizability of \ensuremath{\pi} bonding. Visible Raman data on disordered, amorphous, and diamondlike carbon are classified in a three-stage model to show the factors that control the position, intensity, and widths of the G and D peaks. It is shown that the visible Raman spectra depend formally on the configuration of the ${\mathrm{sp}}^{2}$ sites in ${\mathrm{sp}}^{2}$-bonded clusters. In cases where the ${\mathrm{sp}}^{2}$ clustering is controlled by the ${\mathrm{sp}}^{3}$ fraction, such as in as-deposited tetrahedral amorphous carbon (ta-C) or hydrogenated amorphous carbon (a-C:H) films, the visible Raman parameters can be used to derive the ${\mathrm{sp}}^{3}$ fraction.
12,593 citations
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28 Sep 2004TL;DR: Mechanical Alloying (MA) is a solid-state powder processng technique involving repeated welding, fracturing, and rewelding of powder particles in a high-energy ball mill as mentioned in this paper.
Abstract: Mechanical alloying (MA) is a solid-state powder processng technique involving repeated welding, fracturing, and rewelding of powder particles in a high-energy ball mill. Originally developed to produce oxide-dispersion strengthened (ODS) nickel- and iron-base superalloys for applications in the aerospace industry, MA has now been shown to be capable of synthesizing a variety of equilibrium and non-equilibrium alloy phases starting from blended elemental or prealloyed powders. The non-equilibrium phases synthesized include supersaturated solid solutions, metastable crystalline and quasicrystalline phases, nanostructures, and amorphous alloys. Recent advances in these areas and also on disordering of ordered intermetallics and mechanochemical synthesis of materials have been critically reviewed after discussing the process and process variables involved in MA. The often vexing problem of powder contamination has been analyzed and methods have been suggested to avoid/minimize it. The present understanding of the modeling of the MA process has also been discussed. The present and potential applications of MA are described. Wherever possible, comparisons have been made on the product phases obtained by MA with those of rapid solidification processing, another non-equilibrium processing technique.
3,773 citations
TL;DR: In this article, the authors used a scanning confocal approach to collect spectral data with spatial resolution, which allows them to directly compare Raman images with scanning force micrographs.
Abstract: We present Raman spectroscopy measurements on single- and few-layer graphene flakes. By using a scanning confocal approach, we collect spectral data with spatial resolution, which allows us to directly compare Raman images with scanning force micrographs. Single-layer graphene can be distinguished from double- and few-layer by the width of the D' line: the single peak for single-layer graphene splits into different peaks for the double-layer. These findings are explained using the double-resonant Raman model based on ab initio calculations of the electronic structure and of the phonon dispersion. We investigate the D line intensity and find no defects within the flake. A finite D line response originating from the edges can be attributed either to defects or to the breakdown of translational symmetry.
2,310 citations
TL;DR: In this paper, the constitutive relation of graphene and probe the physics of its optical phonons by studying its Raman spectrum as a function of uniaxial strain was uncovered.
Abstract: We uncover the constitutive relation of graphene and probe the physics of its optical phonons by studying its Raman spectrum as a function of uniaxial strain. We find that the doubly degenerate E(2g) optical mode splits in two components: one polarized along the strain and the other perpendicular. This splits the G peak into two bands, which we call G(+) and G(-), by analogy with the effect of curvature on the nanotube G peak. Both peaks redshift with increasing strain and their splitting increases, in excellent agreement with first-principles calculations. Their relative intensities are found to depend on light polarization, which provides a useful tool to probe the graphene crystallographic orientation with respect to the strain. The 2D and 2D(') bands also redshift but do not split for small strains. We study the Gruneisen parameters for the phonons responsible for the G, D, and D(') peaks. These can be used to measure the amount of uniaxial or biaxial strain, providing a fundamental tool for nanoelectronics, where strain monitoring is of paramount importance.
1,762 citations
TL;DR: Multiwalled carbon nanotubes with a mean fracture strength >100 GPa are reported, which exceeds earlier observations by a factor of approximately three and are in excellent agreement with quantum-mechanical estimates for nanot tubes containing only an occasional vacancy defect, and are approximately 80% of the values expected for defect-free tubes.
Abstract: The excellent mechanical properties of carbon nanotubes are being exploited in a growing number of applications from ballistic armour to nanoelectronics. However, measurements of these properties have not achieved the values predicted by theory due to a combination of artifacts introduced during sample preparation and inadequate measurements. Here we report multiwalled carbon nanotubes with a mean fracture strength >100 GPa, which exceeds earlier observations by a factor of approximately three. These results are in excellent agreement with quantum-mechanical estimates for nanotubes containing only an occasional vacancy defect, and are ∼80% of the values expected for defect-free tubes. This performance is made possible by omitting chemical treatments from the sample preparation process, thus avoiding the formation of defects. High-resolution imaging was used to directly determine the number of fractured shells and the chirality of the outer shell. Electron irradiation at 200 keV for 10, 100 and 1,800 s led to improvements in the maximum sustainable loads by factors of 2.4, 7.9 and 11.6 compared with non-irradiated samples of similar diameter. This effect is attributed to crosslinking between the shells. Computer simulations also illustrate the effects of various irradiation-induced crosslinking defects on load sharing between the shells. The mechanical properties of carbon nanotubes rarely match the values predicted by theory owing to a combination of artefacts introduced during sample preparation and inadequate measurements. However, by avoiding chemical treatments and using high-resolution imaging, it is possible to obtain values of the mean fracture strength that exceed previous values by approximately a factor of three.
1,038 citations