As you probably know, carbon nanotubes have very interesting mechanical, electrical and optical properties. The problem, currently, is that they’re too small (relatively speaking) to be of much use. Now, researchers at the University of Cincinnati (UC) have developed a process to build extremely long aligned carbon nanotube arrays.
|Carbon nanotube arrays can also be grown in intricate patterns using metal masks. The figure above shows a CNT array (optical image) of the American flag.|
|The figure above shows a CNT array image of UC|21, representing UC’s strategic mission statement.|
“First, we were able to grow the arrays up to 18 mm,” he says, ticking off the achievements. “Second, we produced a uniform carpet of 12-mm carbon nanotube arrays on a 4-inch wafer, which moves the invention into the field of scaled-up manufacturing for industrial application. Third, we filed a patent application on the inventions at the US Patent and Trademark Office and, fourth, we were invited to participate in a very prestigious workshop (invitation-only) organized by NASA and Rice University, where we presented our latest results. The workshop focused on “Single Wall Carbon Nanotube Nucleation and Growth Mechanisms.” This event was attended by the best scientists in the world working on synthesis carbon nanotubes, from Japan, China, Europe and the United States. Our presentation was accepted very well and confirmed that with the current record of 18-mm-long carbon nanotube arrays, and also with the big area growth on 4-inch wafers, we are leading in manufacturing extremely long CNT arrays.”
The UC substrate for growing CNT arrays is a multilayered structure with a sophisticated design in which a composite catalyst is formed on top of an oxidized silicon wafer. Its manufacturing requires a “clean room” environment and thin-film deposition techniques that can be scaled up to produce commercial quantities. CNT synthesis is carried out in a hydrogen/hydrocarbon/water/argon environment at 750 degrees Celsius. The achievement of growing centimeter-long nanotube arrays provides hope that continuous growth of CNTs in the meter length range is possible. Leonard Rosenbaum, president and CEO of CVD Equipment Corporation, is looking forward to continuing the partnership with UC to bring this technology from the laboratory into full-scale production. UC is also partnering with another company to develop production of long CNT arrays that can be spun into fibers.