The Cutting Edge: COMPUTING / TECHNOLOGY / INNOVATION : Materials That Take the Heat
Scientists at Rensselaer Polytechnic Institute in Troy, N.Y., have developed a process to make high-temperature components for jet engines, smokestack filters, heat- and impact-resistant armor for military vehicles, and many other products. The basic material involved is silicon carbide, a ceramic that has long been known for its excellent performance at high temperatures but has been impossible to form into a safe, reliable, affordable and non-brittle composite material for industrial uses.
To make their composite, which is three times lighter than steel and can withstand temperatures that would melt most metals, the RPI researchers started with commercial silicon carbide fibers, which look something like black fiberglass cloth. The fibers are first placed in a vacuum chamber and impregnated with a liquid, pre-ceramic polymer known as hydriodopolycarbonsilane. They are then placed in a mold and heated in a two-step procedure that eventually reaches 1,000 degrees centigrade. The process is repeated until the composite becomes a solid, armor-hard silicon carbide component.
The manufacturing process is environmentally friendly and less costly when compared to other technologies. Starfire Systems Inc., a company founded by two Rensselaer Ph.D.s and which is housed in the university’s incubator facility, already has contracts to produce composite smokestack filters that remove solid materials from corrosive and extremely hot exhaust streams.
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Reach Out and Touch: Most computer joysticks are heavy and unwieldy, making them ill-suited to the fine pushing and feeling needed for detailed work such as telesurgery. In telesurgery, a surgeon in a city hospital could guide scalpels and other surgical instruments to rate on a patient in a high-tech ambulance in a war zone or in a small town that has no surgeon. No one has actually undergone a long-distance operation, and no one is likely to for some years. But the technology is already under development. One device that telesurgeons might use has already been commercialized. It is known as PHANToM and was developed at the Massachusetts Institute of Technology. PHANToM consists of a small mechanical arm, an amplifier interface to run the arm, a personal computer and the software that controls the whole package. It looks something like a desk lamp with an arm where the bulb normally goes. When a user inserts afingertip into a thimble on the mechanical arm, PHANToM tracks the motion. Computer software exerts an external force on the finger, creating the illusion of interacting with physical objects that appear on the computer screen. Users can replace the thimble with different tools, such as a scalpel or screwdriver. They will feel as if they are using the actual tool. PHANToM can convey the sensations of softness, hardness, friction and other mechanical attributes of an object. Thomas Massie, an MIT graduate student and co-inventor of the device, has started a company called SensAble Devices in Vanceburg, Ky., to market PHANToM under license from MIT. So far, his orders have come primarily from researchers who will write their own software to develop commercial applications for the tool.
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Cool Cleaning: While sandblasting and water-blasting have been around for a long time, recent legislation on hazardous waste disposal has caused the industry to look for methods that reduce the residual waste created by conventional abrasive blasting operations. In a typical operation, up to 85% to 90% of the waste is actually the abrasive itself. Finding an abrasive material that would vaporize or melt would go a long way to solving the waste disposal problem. Supersonic Abrasive Ice-Blasting, which uses tiny ice particles at very high speeds to remove surface dirt, grease, grime and paint, may turn out to be the next environmentally friendly cleaning method. Ice as an abrasive has been tried before but previous systems required large refrigeration equipment, hoses and a delivery system for the ice pellets, making the systems bulky and expensive. Now researchers at Penn State Gas Dynamics Laboratory have come up with a simplified system that makes the ice in the blasting nozzle, eliminating the separate refrigeration machinery and delivery system. It is similar to a snow-making machine, but produces ice rather than artificial snow. The system uses tap water with the addition of a small quantity of an additive used in the snow-making business. The speed of the three- to four-thousandths of an inch ice particles can reach approximately 500 m.p.h. Airplane de-painting is a prime area for ice blasting. So too as a replacement for the chemicals used to degrease automobile parts.
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Space-Age Bulldozers: Combine the Global Positioning System (GPS) with some software developed at Ohio State University and you may have a way for construction companies to help save time and money when surveying and preparing building sites. At the first stages of a project, a GPS receiver is mounted on a vehicle and an operator drives the site to be leveled and graded. Signals from the GPS are gathered by the receiver and that information is used to draw up a map and construction plan for the site. Once the grading begins, the GPS monitors the progress of the bulldozers and other equipment and guides machine operators using a TV-like monitor in the vehicle’s cab. The ultimate aim is to feed signals directly to the vehicle’s hydraulic controls, automating the earth-cutting and filling much as an automated navigation system in an aircraft feeds course information into the aircraft’s controls. But don’t look for a space-age bulldozer at a vacant lot near you any time soon. A prototype of the system currently lists for around $100,000. Ohio State’s Center for Mapping, which developed the software, is currently working with several GPS manufacturing companies to develop a less-expensive system with a narrower scope of operation. The Center for Mapping is one of 11 research and development groups in the United States funded by NASA to promote the commercialization of space.
