Sneak Previews

New ceramic machining process

Ceramics help engine parts, electronics, chemical processing equipment, and artificial joints withstand high temperatures in automotive, aerospace, and other applications where heat damages metals. Widespread use of ceramic components has been hampered by a lack of machining processes, especially with regard to small lot sizes that are produced by machining the components rather than by creating a die and casting them. Yung C. Shin, a professor of mechanical engineering at Purdue University, discovered a new way of machining ceramics that may help make ceramic use more widespread. "We are currently exploring the applicability of this technique to other ceramics, metal matrix composites, and high-temperature alloys," he says. The technique involves heating the ceramic material to 1,800F with a laser, which makes it softer and more ductile. Shin says position and strength of the laser are important to successful machining. "We heat a very small layer of the surface and then remove it immediately so that the interior is not damaged by the heat," he says. His technique is unlike the current machining technology, which uses diamond grinding. Shin estimates that his technique costs about half of what diamond grinding costs. "Being able to shape ceramic parts into desired geometries with precision will lead to increased use of ceramics for engineering parts," he says. Shin estimates the technology will be ready for commercialization in about one year. Contact Shin at shin@ecn.purdue.edu  or call (765) 494-9775.

Chips with ridges

Microfluidic devices are important to the development of microscopic gadgets such as DNA analyzers, chemical detectors, and other lab-on-chip applications. One of the difficulties with the assembly of the tiny structures is the creation of the microscopic channels. Researchers at the Department of Energy (DOE) have created a new patented microchip processing technique that creates raised canals eight to 100 microns wide, through which gases and liquids flow. "This new process integrates with other microdevices," says Carolyn Matzke, one of the process developers. "Ours is a very benign single-layer process. And because it's a single-layer process, we save about half on the material costs," she says. DOE researchers pattern a thin layer of photoresist on the wafer's surface using a conventional photomask and light, then develop areas of the photoresist exposed to light. What is left is a network of ridges on the wafer's surface. Then, researchers heat the wafer to 212F for 20 seconds, which causes the square-edged ridges to slump in a hemispherical shape. A two-micron-thick film of silicone oxynitride is deposited over the rounded photoresist and the entire wafer is soaked in acetone until the remaining photoresist dissolves, which leaves hollow channels on the wafer surface. For more information, contact Matzke at (505) 844-7193 or fax (505) 844-8985.

Flexible 'glass'

Gordon Graff and other materials researchers at Pacific Northwest National Laboratory (PNNL) developed a flexible plastic-film coating for organic light-emitting diodes that provides moisture protection similar to glass. Plastics typically allow penetration of water vapor, which harms sensitive components of displays found in computer monitors, cell phones, and wristwatches. The coating is a series of protective layers that are stacked during a vacuum process. "The stacking architecture allows each layer to help protect against defects in adjacent layers, which significantly lowers the permeation rate of gases through the film," says Graff. Contact www.pnl.gov .

Chip has new laser configuration

Compact disc-recordable (CD-R) media use infrared lasers for recording data on the disks. Recording and playback of data requires separate lasers on a single chip. First, a lens focuses light on the disk. When the temperature at the light focal point reaches several hundred degrees Celsius, it causes a chemical reaction that creates pits in the recording media. The pits act as the binary agents. Detecting the pits requires a weak light that goes through a lens, hits the recorded surface, and bounces back to photodetectors in the pickup. Matsushita Corp. (Tokyo, Japan) is reducing the size required of such chips to 0.3 mm wide by 0.8 mm long. The new technology enables integration of a high-speed CD-R pickup with a digital versatile disc pickup in the same device. The chip's gallium arsenide substrate has side-by-side 780-nm and a 650-nm infrared lasers. The new chip prevents light absorption, which triples output power to 100 mW. It also reduces by two-thirds the amount of current to the laser. Matsushita uses computer simulations that it developed with Stanford University to adjust structure sizes, so both lasers could be contained on the same chip. For more information, call (650) 723-2300.

Cylinder design saves energy

Argonne National Laboratory is using its compact heat exchanger technology for development of a multiport cylinder dryer. The new dryer is expected to improve the drying rate more than 30% in pulp and paper processing applications. Pulp and paper processing is the nation's most energy-intensive manufacturing process, according to the U.S. Department of Energy. Current drying technology limits productivity at pulp and paper mills. So improving drying efficiency is expected to improve the U.S. industry's ability to compete in global markets. The technology developed at Argonne National Lab involves flowing steam through multiport passages that are in close proximity to the cylinder dryer surface. The new dryer contains small-channel heat exchangers that have high heat-transfer surface areas. The multiport dryer design minimizes condensate formation that reduces heat flow. Its surface also maximizes the amount of surface area available for heat transfer, so it achieves higher drying rates than traditional dryers used in pulp and paper applications. High performance multiport condensers are currently used in air conditioners in the automobile industry. The multi-port drying design retrofits onto existing cylinder dryers. A prototype will be designed for the research and development center at the Johnson Corp. For more information, contact Argonne National Laboratory, Energy Technology Div., (630) 252-6439, or the U.S. Department of Energy, Office of Industrial Technologies, (202) 586-0937.

OLED technology proliferates

The Eastman Kodak Co. formed a strategic partnership with Sanyo Electric Co. and ULVAC Ltd. (Japan) to jointly develop organic light-emitting diode (OLED) technology. OLED is a self-luminous display technology based on thin organic films as the light emitter. Like conventional inorganic light-emitting diodes, OLED requires a low-drive voltage for producing bright visible light. Unlike discrete LED, which has crystalline origins, film-based OLED is an area emitter that can easily be patterned to produce flat-panel displays. Because OLED is self-luminous, it does not require a backlight as in liquid-crystal displays (LCD). It has very low power requirements and is thin, bright, and energy efficient. Applications include digital cameras, camcorders, pagers, watches, and automotive display clusters. Visit Kodak's website at www.kodak.com or call (716) 722-0223.

Electronic devices and copper corrosion

Copper, as a conductive metal, is essential for many electronic devices. That's why researchers at Sandia National Laboratory are conducting experiments aimed at understanding how copper corrodes. "Our immediate focus is on copper corrosion in discrete components such as diodes and resistors," says Charles Barbour, the project's principal investigator. "We also see applications for these experiments in printed circuit boards and microelectronics," he says. Barbour and his team at Sandia evaporated a thin copper film onto silicon wafers with an electron beam. They then etched portions of the copper film using a photolithography process that left 16 "meander lines" of copper. The lines formed electrical resistors used for measuring corrosion as a function of time. Resistive elements were implanted with indium, oxygen, deuterium, and aluminum ions. After exposing the copper to hydrogen sulfide, the researchers calculated the thickness of copper sulfide corrosion. They determined that indium slows corrosion and deuterium speeds corrosion. "Eventually, we'll have computer code that predicts copper corrosion rates," says Barbour. The computer code will help users predict the life of electronic devices. Contact Barbour at jcbarbo@sandia.gov or call (505) 844-5517.