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Graphene has potential in automotive, aerospace, wind energy, electronics industry

Graphene has potential in automotive, aerospace, wind energy, electronics industry

14-Jun-10

Graphene is a flat one-atom thick sheet of carbon; the two-dimensional crystalline form of carbon: a single layer of carbon atoms arranged in hexagons, like a sheet of chicken wire with an atom at each nexus. Graphene remains capable of conducting electricity even at the limit of nominally zero carrier concentration because the electrons do not appear to slow down or localize. The possible reason is because the electrons moving around carbon atoms interact with the periodic potential of graphene�s honeycomb lattice, which gives rise to new quasi particles that have lost their mass, or 'rest mass'. Electrons can move at high speeds through graphene so fast that their behavior is governed by relativity rather than classical physics. The mobility of electrons in graphene is by far the highest of any known material. Since they suffer little energy loss, graphene is an ideal candidate for future electronics applications, especially at the nanoscale. Because of graphene�s planar geometry, it may be more compatible with conventional electronic devices than other materials, including carbon nanotubes. Graphene could replace silicon in the next generation of semiconductors, making them considerably smaller and faster than present technology. Graphene not only has outstanding electrical conductivity but also thermal conductivity, combined with strength and barrier, which makes it an exciting new material in the development of conductive applications. It is exceptionally strong and versatile - its strength is, pound for pound, 200 times that of steel, though it is a remarkably simple material, composed of nothing but carbon atoms arranged in a simple, regular pattern. Its unusual properties make it ideal for applications in newer technologies of microchips, chemical sensing instruments, biosensors, flexible displays, etc. Because of its single-atom thickness, pure graphene is transparent, and can be used to make transparent electrodes for light-based applications such as light-emitting diodes (LEDs) or improved solar cells. The potential solar cell applications are now being studied by some researchers. Graphene could be a substitute for copper to make the electrical connections between computer chips and other electronic devices, providing much lower resistance and thus generating less heat.
The most immediate application for graphene is probably its use in composite materials. Conductive plastics at less than 1 volume percent filling, at low production costs makes graphene-based composites attractive for a variety of uses. Graphene has potential market in composite industry as its properties include reduced solvent swelling, electrostatic dissipation, lower CTE and improved heat dissipation, preventing hot-spots that might cause polymer degradation in automotive under-the-hood parts exposed to chemicals and extreme temperatures. Other potential applications include fuel systems that require both high barrier and electrical conductivity, electrostatic dissipative (ESD), packaging for electronics, electromagnetic and radio frequency interference (EMI/RFI) shielding in electronic enclosures, and parts that can be electrostatically painted.
There are only a few manufacturers of graphene in the World. Angstron Materials is working on nano graphene platelets (NGPs). Angstron is able to provide pristine graphite and single layer graphene. Graphene Solutions is a manufacturer of purified and size selected carbon nanotubes, graphene and nanographene. USA based Vorbeck Materials Corporation and XG Sciences are also graphene makers. US manufacturers are associated with university research.
A Michigan State University (MSU) team developed a nanomaterial-xGnP Exfoliated Graphite NanoPlatelets-that makes plastic stiffer, lighter and stronger. The key to the new material�s capabilities is a fast and inexpensive process for separating layers of graphite (graphene) into stacks less than 10 nanometers in thickness but with lateral dimensions anywhere from 500 nm to tens of microns, coupled with the ability to tailor the particle surface chemistry to make it compatible with water, resin or plastic systems. The small stacks of graphene can replace carbon nanotubes, nano-clays, or other carbon compounds in many composite applications. When added in small amounts (2-3%) to plastics or resins, the nanoparticles make these materials electrically or thermally conductive and less permeable, while simultaneously improving mechanical properties like strength, stiffness, or surface toughness. When used alone or in conjunction with carbon or glass fibers, the nanoparticles enhance electrical and thermal conductivity-producing strong, lightweight composites suitable for aerospace, automotive, or electronic applications. Combined with metal nanoparticles, (xGnP + nanoparticle), the material has potential for applications in fuel cells, supercapacitors, batteries and hydrogen storage. The material will be instrumental in the development of new and expanded applications in the aerospace, automotive and packaging industries. The graphene nanoparticles are being manufactured by a new startup company, XG Sciences Inc., located in mid-Michigan and a spinoff from intellectual property owned by MSU. Potential applications of xGnP include:
• Lighter, more fuel-efficient aircraft and car parts, and stronger wind turbines, medical implants and sports equipment.
• Surface coatings on Li-ion electrodes and transparent conductive coatings for solar cells and displays.
• Lightweight gasoline tanks and leak-tight and plastic containers that keep food fresh for weeks.
Vorbeck Materials is making inroads in graphene technology with its Vor-ink conductive inks and Vor-x graphene formulations and composites. Vorbeck Materials utilizes technology originally licensed from Princeton University, where three of Vorbeck's founders were professors. In conjunction with BASF, Vorbeck established a joint research program to develop graphene-based formulations and composite materials. As part of the collaboration, Vorbeck and BASF are developing dispersions of highly conductive graphene for producing electrically conductive coatings and compounds, especially for the electronics industry. Graphene formulations offer key benefits, most notably improved conductivity; even in thin coatings of 1 micron, Vorink maintains its rated conductivity. Vorbeck has developed a scalable process and commissioned a pilot plant capable of manufacturing graphene in ton quantities.
Researchers from Rice University and the Technion-Israel Institute of Technology have developed a method for producing bulk quantities of graphene, that yields very pure material, and is based on bulk fluid-processing techniques. The team found it could dissolve graphite in chlorosulphonic acid, a common industrial solvent. The researchers had to devise new methods to measure the aggregation of the dissolved graphene flakes, but at the end the team found that the individual graphene layers in the graphite peeled apart spontaneously. The team was able to dissolve as much as 2 grams of graphene/liter of acid to produce solutions at least 10 times more concentrated than existing methods. The researchers took advantage of novel cryogenic techniques for electron microscopy that allowed them to directly image the graphene sheets in the chlorosulfonic acid. The team applied new methods developed to directly image carbon nanotubes in acid. Using the concentrated solutions of dissolved graphene, the scientists made transparent films that were electrically conductive. Such films could be useful in making touch screens that are less expensive than those used in today's smart phones. In addition, the researchers also produced liquid crystals. If the method proves useful for making graphene fibers in bulk, it could drive down the cost of the ultrastrong carbon composites used in the aerospace, automotive and construction industries. Use of graphene powder in electric batteries is a possibility as an ultimately large surface-to-volume ratio and high conductivity provided by graphene powder can lead to improvements in batteries� efficiency, taking over from carbon nanofibres used in modern batteries. Graphene offers clear advantages in material for solid-state gas sensors. Spin-valve and superconducting field-effect transistors are also obvious research targets. Researchers in the Electro-Optics Center (EOC) Materials Division at Penn State have produced 100 mm diameter graphene wafers, a key milestone in the development of graphene for next generation high-power, high-frequency electronic devices. Using a process called silicon sublimation, the team thermally processed silicon carbide wafers in a high temperature furnace until the silicon migrated away from the surface, leaving behind a layer of carbon that formed into a one- to two-atom-thick film of graphene on the wafer surface. The EOC wafers were 100 mm in diameter, the largest diameter commercially available for silicon carbide wafers, and exceeded the previous demonstration of 50 mm. Penn State is currently fabricating field effect transistors on the 100 mm graphene wafers and will begin transistor performance testing in early 2010. A further goal is to improve the speed of electrons in graphene made from silicon carbide wafers to closer to the theoretical speed, approximately 100 times faster than silicon. That will require improvements in the material quality, but the technology is new and there is plenty of room for improvements in processing.
The market for carbon nanotubes (CNTs), nanofibers, fullerenes and POSS and graphene grew at an annual rate of 30% pa up to 2008; as per Reportlinker.com. However the market slowed down due to the global recession but picked up again in Q4-09, driven by demand from the semiconductors, electronics and energy markets. These will continue to be the main application markets through to 2015, when the market for these nanomaterials will account for an estimated US$2912 million in revenues. Main market drivers include the need to improve the performance and speed of semiconductors and electronics, reduce costs and increase safety in aerospace and military applications, and increase the efficiency of renewable energy devices.
Graphene is being studied worldwide for electronics, displays, solar cells, sensors, and hydrogen storage. Graphene has the potential to enable terahertz computing, at processor speeds 100 to 1,000 times faster than silicon. For a material that was first isolated only five years ago, graphene is off to a fast start.

 
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