Graphene thermal conductivity - introduction and latest news - Page 17

Researchers at Purdue University suggest wrapping silver nanowires with an ultrathin layer of graphene can protect the structures from damage and could represent a key to realizing their commercial potential. Silver nanowires are known to hold promise for applications such as flexible displays and solar cells, but their susceptibility to damage from UV radiation and harsh environmental conditions has limited their commercialization.

The scientists state that Devices made from silver nanowires and graphene could find uses in solar cells, flexible displays for computers and consumer electronics, future "optoelectronic" circuits and more, since that graphene "extracts and spreads" most of the thermal energy away from the nanowires. Raman spectroscopy was performed by the Purdue Department of Physics and Astronomy and findings showed the graphene sheathing protected the nanowires even while being subjected to 2.5 megawatts of energy intensity per square centimeter from a high-energy laser, which vaporizes the unwrapped wires. The unwrapped wires were damaged with an energy intensity as little as .8 megawatts per square centimeter. The graphene also helps to prevent moisture damage.

Researchers at Stanford University have recently performed three separate experiments that suggest graphene in computing and telecommunications could radically cut energy consumption. This work was done in search of post-silicon materials and technologies that enable storing more data per square inch and use a fraction of the energy of currently used memory chips.

All three experiments involve graphene, and test different ways to use it in new storage technologies. The scientists claim that graphene can have interesting mobile applications of these new technologies, but post-silicon memory chips may transform server farms that store and deliver quick access to enormous quantities of data stored in the cloud.

Group NanoXplore is a Montreal-based company specializing in the production and application of graphene and its derivative materials. The company's CEO and President, Dr. Soroush Nazarpour, was kind enough to answer a few questions we had regarding NanoXplore's technology and business.

Q: Hello Dr. Soroush. Can you update us on your current graphene material production and your new 3-ton GNP production facility?

Our Montreal production facility is running at full steam. Not only are we producing a full range of graphene materials, we are making more and more graphene-enhanced polymer products. In October we will be moving to a new facility, having outgrown our current space. The new facility will double our lab facilities and more than quadruple our production floor space.

We are seeing especially strong demand for graphene-enhanced plastics and rubber, with most customers focusing on improving mechanical and thermal characteristics. We have also seen a lot of emerging demand for coatings for textiles and other flexible substrates for thermal management, improved surface properties and protection.

A few weeks ago we reported on a new IDTechEx market report, in which they predict that the graphene market will reach nearly $200 million by 2026, with the estimation that the largest sectors will be composites, energy applications and graphene coatings.

We were very interested in learning more, and Dr Khasha Ghaffarzadeh, IDTechEx's head of consulting was kind enough to answer a few questions and explain the company's view on the graphene market.

Q: IDTechEx has been following graphene for a long time with dedicated events and reports. Why is this new material interesting for IDTechEx?

We have a long track record of analyzing emerging advanced materials such as quantum dots, CNTs, Ag nanostructures, silicon nanostructures, OLED materials, etc. We were however pulled into the world of graphene by our clients’ questions. Once in, we soon realized that there is a big synergy between graphene and our events. in fact, our events on supercapacitors and printed electronics were the right near-term addressable market for graphene, and that is why we managed to rapidly build up the largest business-focused event on graphene. Our events on graphene are held in the USA and Europe each year see www.IDTechEx.com/usa.

Researchers at Rice University developed a theoretical model that shows how a 3D lattice of boron nitride (also known as "white graphene" as it shares many similar qualities with it, but is not made of carbon atoms) could be deployed as a tunable material to control heat flow in electronic devices. Cooling measures that prevent overheating in electronics are important for developing and sustaining advanced electronic components.

Its 3D structure allows the speculated boron nitride system to conduct heat in any direction as opposed to most circuits, in which heat moves in one direction. The multiple heat directing properties of boron nitride provide excellent opportunities to ‘cool’ down electronic devices. This can be controlled further by building pillars of boron nitride of differing shapes and thickness.

Researchers at the University of Illinois at Chicago, the University of Massachusetts-Amherst and Boise State University explored the effects of boundaries between grains of graphene on its heat conductivity by developing a technique to measure heat transfer across a single grain boundary. 

The surprising results revealed an order of magnitude (about 10 times) lower than the theoretically predicted value. The scientists then devised computer models that can explain the surprising observations from the atomic level to the device level. The team developed an experimental system that lays down a graphene film onto a silicon-nitrate membrane around four-millionths of an inch thick and can measure the transfer of heat from one single graphene crystal to another. The system is sensitive to even the tiniest changes, like nano-scale grain boundary. When two crystals are neatly lined up, heat transfer occurs as predicted by theory. When two crystals have mis-aligned edges, though, the heat transfer that occurs is 10 times less. 

A team of researchers at MIT developed a method of coating condensers used in power plants with graphene, to make them durable and transfer heat rapidly. Condensers are the equipment that collects steam and condense them back to water in electricity-producing plants. Improving their efficiency could greatly contribute to the overall power plant efficiency.

The scientists coated the condenser surfaces with a layer of graphene, and found that this can improve the rate of heat transfer by a factor of four. The improvement in condenser heat transfer could lead to an overall improvement in power plant efficiency of 2 to 3 percent, enough to make a significant change in global carbon emissions.

Researchers at The Institute of Advanced Composite Materials at Korea Institute of Science and Technology (KIST) and The Seoul National University announced that they have successfully developed a manufacturing process for high molecular composite material with even distribution of graphene without using solvent.

Researchers developed this composite material after applying heat to a mixture of cyclic butylene terephthalate (CBT) with graphene particles. With statistical calculations using a cross sectional image of graphene, the researchers evaluated the distribution of graphene with average inter-particle distance and standard deviation.

Ohio-based Angstron Materials has developed a group of cost-effective thermal foil products that can be customized for handheld devices and other products. The company says that its foil sheets have been qualified for use by a major mobile electronics company. Such thermal foils can be used for the technology beneath devices' screens that conducts heat away from internal electronic components and batteries to help maintain optimal performance.

Angstron’s thermal foils are available in a variety of grades. The company states that its foils are thinner than other products on the market and so give manufacturers greater design flexibility than competing methods. Angstron’s foil sheets also can be sourced with equivalent or greater thermal conductivity.

Researchers at Purdue University designed a new process for coating copper nanowires with graphene, that lowers resistance and heating. This process may suggest potential applications in computer chips and flexible displays, as copper nanowires are essential for efficient data transfer and heat conduction in such applications.

The researchers developed a technique for encapsulating the wires with graphene, which was shown to create hybrid wires that are capable of 15% faster data transmission while lowering peak temperature by 27% compared with uncoated copper nanowires. The graphene coating prevents the copper wires from oxidizing, preserving low resistance and reducing the amount of heating.