Technology bulletin

Building structures from ink

A Sandia National Lab professor of chemical and nuclear engineering discovered a process called "evaporative induced self assembly" that is used for building miniature structures from ink. Instead of using standard lithograph processes, the self-assembling ink is easily printed from ordinary inkjet printers. The new process shows promise because it does away with tedious, sequential deposition of individual organic and inorganic layers, a process that is much more time-consuming for the building of miniature structures and nano-structures. "Possible uses for the small structures include separating proteins in bio-technology applications, monitoring the pH of fluids transported by capillary action, and miniature sensing devices for chemical and biological weapons," says Jeff Brinker, a senior scientist at the lab. He says it is possible to create functional structures in seconds with CAD drawings. "Instead of designing and painstakingly cutting fluid channel networks, we fabricate a substance that organizes itself," he says. Brinker also envisions a way of making a valve by creating molecular pores that change shape from external input. He says that combining different types of ink is possible for meeting differing functional requirements such as strengths and dialectic properties. Contact Brinker at (505) 272-7627.

Myths about effect of manganese disproved

Specifying a low manganese content in the stainless-steel tubing used for high-purity gas distribution systems is said to improve corrosion resistance, especially in welded systems exposed to corrosive gases. This belief is being disproved by a new study conducted at Swagelok (Solon, OH) in which research metallurgist Sunniva Collins, Ph. D. examined the corrosion characteristics of AISI 316L electropolished tubing in "as received" and welded condition. "We found that manganese had no effect on corrosion resistance," says Collins. Swagelok conducted 21 "heats" of commercially available 316L electropolished tubing with manganese content varying from 0.15 to 1.82%. Welded tube samples from each lot were evaluated for corrosion resistance using standard ASTM test methods. More than 300 individual corrosion tests—including critical pitting temperature and hydrochloric acid immersion tests—were performed. Based on the test results, Swagelok concludes that there is no greatly enhanced corrosion resistance of low-manganese tubing under welded or corrosive conditions. The findings call into question the validity and necessity of passivation techniques and other surface finish requirements. Results from the study illustrated the strong reproducibility of ASTM G150, the critical pitting temperature test method. The test method was shown to be quick, inexpensive, and easy to perform. The Semiconductor Equipment and Materials International task force adopted ASTM G150 as the basis for functional corrosion testing for the industry due in part to the breakthrough results of this study. A strong correlation was found between base chemistry and corrosion resistance before and after welding. The study also raises questions about quality assurance requirements. Contact Collins at Sunniva.Collin@Swagelok.com, fax (440) 951-4872, call (440) 349-5934, or visit the Swagelok website at www.swagelok.com .

Device 'hears' power line problems

A team of scientists from the Colorado School of Mines believes it has a better way of analyzing problems in the thousands of miles of electric power lines strung in the U.S. For power companies, it's often difficult to determine where electric line failures might occur and how to avoid interruptions in service. The current method involves flying along power lines in helicopters and looking for potential problems—an imprecise system at best. Some power lines are also buried underground, so diagnosing and predicting problems in these areas is extremely impractical. A new device developed at Colorado School of Mines may soon solve diagnostic and predictive maintenance problems with acoustic technology. The Electro-magnetic acoustic transducer (EMAT) device uses a high-frequency acoustical transmitter and receiver. The device attaches to live power lines at any point, commonly at ground level. By "listening to and analyzing" the acoustical profile of the line, the device detects problems and pinpoints the exact location on the line where the problem can be found. The device is currently undergoing laboratory trials. It is awaiting final patent approval. Contact Dr. Rohmat Shourishi at (303) 384-2032 or visit the Colorado School of Mines' website at www.mines.edu .