Graphene, at 1,000 GPa: The Strongest Material Ever Tested
by Jeffrey Winters

Visions of nanotubes and buckyballs have long been dancing in the heads of boosters of nanotechnology. But another form of carbon has begun receiving more attention of late. Called graphene, these flakes of carbon are one atom thick and can be made from graphite using very simple methods. What’s more exciting is that some experts predict that the substance, which was unknown until 2004, may well be the strongest material known.

Research engineers are scrambling to better understand graphene and a group led by James Hone, a professor of mechanical engineering at Columbia University in New York, recently published some of the most precise measurements yet recorded for the strength and elasticity of graphene. The research group hit upon a clever way of performing the measurements. The engineers imprinted micrometer-size holes in a silicon slab, then dropped flakes of graphene on the slab. They then used the tip of an atomic force microscope to push on the flake at the exact center of the hole.

Much like a finger pushing on plastic wrap over the mouth of a soda bottle, the ATM tip started deforming the graphene until the carbon material ruptured. The strength of the flake was astonishing—the Young’s modulus was 1,000 gigapascals, which makes graphene the strongest material ever tested. (The Young’s modulus for aluminum is about 70 gigapascals.) “It’s literally off the chart,” Hone said.

Perhaps more interesting to materials scientists is the measurement of third order elastic stiffness, which is -2.0 terapascals. “The term is difficult to reach experimentally,” Hone said, because most materials fail well before they reach the point where it can be measured. Hone said that the third order elastic stiffness measurement for graphene will serve as a benchmark for the term in other, more easily ruptured materials.
Graphene itself may find a use in composite materials in the near future. Unlike carbon nanotubes, which require elaborate steps to fabricate, graphene flakes can be produced by sticking transparent tape to the top of a graphite block and then peeling it away.

IDAHO AND ARGONNE TO STUDY VERY HIGH TEMP REACTOR
by Jeffrey Winters

One of the designs being considered for the so-called Generation IV nuclear power program is the very high temperature gas-cooled reactor. The reactor would operate at such high temperatures that it could do more than just generate electricity. Some plans, for instance, call for these reactors to thermally crack water to create hydrogen.

Another potential job for the VHTR will be investigated by Idaho National Laboratory and Argonne National Laboratory under a $7.3 million contract awarded by the Department of Energy in July. The labs will lead research into technology to destroy plutonium and other transuranic elements within the reactor. Not only would the process reduce hazardous nuclear waste, but it would also generate useful process heat.

The project, called the Deep Burn research and development program, will also be coordinated with the DOE’s Global Nuclear Energy Partnership, which aims to reprocess spent fuel in order to help extend nuclear fuel stocks.    

ASME ADVISES FUNDING TO MEET ENERGY DEMAND
by John Varrasi

ASME has asked the U.S. Congress to direct funds to programs that will enable the United States to develop the national energy infrastructure to meet the rising demand for transportation fuels and electricity.

An ASME position statement urges members of the Senate and House Appropriations Committees to increase funds for technology development and innovation as well as to train workers in “green collar” jobs. The administration already has enacted the Energy Independence and Security Act of 2007. Several key provisions of the act, however, including the appropriation of funds, remain unresolved.

Echoing the public sentiment to wean the United States from dependence on foreign energy supplies, the ASME position statement references the need to displace traditional sources of energy, while updating the national energy infrastructure.

The ASME position statement holds that, in addition to the large capital expenditures required to design, build, operate, and maintain new energy systems, funds also are needed to train and employ workers to produce green power.

“The evolution of new ‘green collar’ jobs…could catalyze a new generation of engineers and scientists in our nation,” the statement says.

The Institute of Electrical and Electronic Engineers, American Institute of Chemical Engineers, and American Society of Heating, Refrigeration, and Air Conditioning Engineers have collaborated with ASME on the outreach effort.

IN-HOME ANALYSIS
by Jean Thilmany

Lab-on-a-chip devices could one day be the brains behind in-home tests for illnesses, food contaminants, and toxic gases. But today these portable devices are stuck in the lab themselves.

A lab-on-a-chip integrates multiple laboratory functions onto one chip just millimeters or centimeters in size. It is usually made of nano-scale pumps, chambers, and channels etched into glass or metal. These microfluidic devices, which operate with drops of liquid about the size of the period at the end of this sentence, allow researchers to conduct quick, efficient experiments.

They can be engineered to mimic the human body more closely than the Petri dish does and are useful in growing and testing cells, among other applications.

Now, researchers at the University of Michigan in Ann Arbor seek to make the technology accessible via a 16-piece lab-on-a-chip kit intended to bring microfluidic devices to the scientific masses. The kit cuts the time to make a microfluidic device from days to minutes, said Mark Burns, a professor in the departments of biomedical engineering and chemical engineering who developed the device with graduate student Minsoung Rhee.

“In a lot of fields, there can be significant scientific advances made using microfluidic devices and I think that has been hindered because it does take some degree of skill and equipment to make these devices,” Burns said. “This new system is almost like Lego blocks. You don’t need any fabrication skills to put them together.”

Burns believes microfluidics will go the way of computers, smaller and more personal as technology advances. And his system can help.

“Thirty or 40 years ago, computing was done on large-scale systems. Now everyone has many computers, on their person and in their house. It’s my vision that in another few decades, you’ll see this trend in microfluidics,” Burns said. “You’ll be analyzing chicken to see if it has salmonella. You’ll be analyzing yourself to see if you have influenza or analyzing the air to see if it has noxious elements in it.”

Burns’s system offers six-by-six millimeter blocks etched with different arrangements of grooves. Researchers can arrange the blocks to make a custom device by sticking them to a piece of glass, Burns said. Block designs include inlets, straight channels, Ts, Ys, pitchforks, crosses, 90-degree curves, chambers, connectors (imprinted with a block M for Michigan), zigzags, cell culture beds, and various valves. The blocks can be used more than once.

Most of the microfluidic devices that life scientists currently need require a simple channel network design that can be easily accomplished with this new system, Burns said. To demonstrate the viability of his system, he successfully grew E. coli cells in one of these modular devices.

SUPERCONDUCTORS VS. SEA MINES
by Harry Hutchinson

The U.S. Navy is testing a system based on high-temperature superconductors as a lightweight, more efficient method of masking the magnetic signatures of its ships.

The Office of Naval Research and the Naval Surface Warfare Center Carderock Division’s Ship Engineering Station Philadelphia have installed a high-temperature superconducting degaussing coil system on board a destroyer, the USS Higgins, at the naval station in San Diego, Calif. The degaussing coil will undergo a series of sea trials and demonstrations over the next two years.

Test ship: The Arleigh Burke-class guided missile destroyer USS Higgins, shown here at sea near San Diego in 2001, has been fitted with a superconductive system designed to mask its magnetic field from mines.

Photo Courtesy of Photographer’s Mate 2nd Class Frederick McCahan/U.S. Navy

Degaussing neutralizes a ship’s magnetic field by sending electrical currents through a series of metal cables encircling all or part of the hull. It protects ships from undersea magnetic mines, which detonate or activate when they detect magnetic fields.

The HTS wire and magnetic cable technology were supplied by American Superconductor in Devens, Mass. In April 2006, an internal R&D project funded by the company demonstrated the first full-scale HTS-based degaussing coil. According to the company, the 40-meter HTS degaussing coil produced 4,100 amp-turns, a typical level of performance of conventional copper-based degaussing systems deployed in military ships today. AMSC’s degaussing coil achieved this with an operating voltage of less than 0.5 volt, lower by a factor of 1,000 than copper-based systems.

The Navy said the test system on the Higgins uses a single cable made from high-temperature superconducting wire that significantly reduces the overall weight and installation costs. HTS wires cooled to cryogenic temperatures can be operated at current densities 150 to 200 times higher than ambient temperature conductors.

Superconductive degaussing: American Superconductor has developed a degaussing coil using its high-temperature superconductors, making it lighter and more compact than conventional systems. A version of the HTS coil is being tested on a U.S. Navy destroyer.

Photo Courtesy of American Superconductor

The Higgins (DDG 76) is an 8,000-ton Arleigh Burke-class destroyer. The Navy is considering the system for other classes of ships as well because it would be lightweight and occupy less space. Smaller and lighter systems will let the ships carry more weapons and other equipment.

A statement by the Navy said: “With reductions in the number and weight of cables, HTS degaussing systems projected for the LPD-17, LCS, CG(X), DDG-1000, and CVN-21 classes of ship will show an estimated 50%-80% reduction in total system weight and a reduced total ownership cost compared to the current system. In addition, there will be a 90% reduction in the total installed cable lengths for all Navy ship classes.”

The Navy said industry partners contributing to the system include Nexans GmbH, PHPK Industries, Cryomagnetics, and Cryomech. Key components—such as an HTS connector for attaching HTS cables to each other, and an advanced HTS cable assembly—are under development through Navy Small Business Innovation Research investments under ONR and Naval Sea Systems Command sponsorship.     

BRIEFLY NOTED

Siemens PLM Software of Plano, Texas, has released version six of its CAM Express software. The application is the numerical control programming software component of the vendor’s Velocity Series portfolio of engineering applications. As such, the new release covers a variety of programming requirements, from high-speed machining to multifunction mill turning to 5-axis machining.

Popular television personality Nate Ball, host of the PBS program Design Squad, will host the 2008 ASME Innovation Showcase to be held Oct. 31, in Boston. ASME IShow, now in its second year, provides a forum for students to present their innovative product designs to a panel of judges, while demonstrating the product’s potential to impact commercial markets.

Coade of Houston has released its CADWorx Plant Design Suite 2009, the latest version of its CAD series for process plant design. This latest release includes valve top-works capabilities that allow users to place valve hand wheels, levers, actuators, and other items using specification-driven selection routines.

A team led by Boeing Advanced Systems has been awarded a Defense Advanced Research Projects Agency contract to develop the plan for a demonstration version of a high-power generation subsystem for spacecraft. Team members include DR Technologies, Northrop Grumman Astro Aerospace, Texas A&M University, Spectrolab Inc., and key suppliers.