Developments to Watch
PRODUCING CARBON-CARBON FAST-FAST
Carbon-carbon composites are the stuff of desperation. They're among the toughest, most heat-resistant materials around, but they're such a pain to produce that they're used only when nothing else will do. Such as for the exhaust nozzles on NASA rockets. Or for jetliner brake linings, where lightweight, carbon-reinforced carbon composite not only saves pounds but outlasts steel linings 2 to 1.
Four months ago, W.J. "Jack" Lackey, a senior researcher at Georgia Tech Research Institute, had an inspiration. He hung a so-called preform--a mat with multiple clothlike layers woven from carbon fibers--in an oven and heated it to 1,200C. Next, he forced methane gas through the preform. When methane molecules came into contact with the hot preform, they broke down and deposited their carbon atoms on the fibers. After eight hours, carbon atoms filled all the voids and turned the mat into a solid sheet. The usual method--repeatedly soaking a mat with a resin and baking off the noncarbon atoms--produces toxic gases and takes weeks. Lackey says his process is 30 times as fast. That could make carbon-carbon parts affordable for car engines.EDITED BY RUTH COXETER