metal mesh currently used in the structure of the composite aircraft to disperse lightning strikes, buckypaper, with its high current-carrying capacity, would allow lightning’s elec- trical charge to flow around the plane and dissipate without causing damage.
Furthermore, buckypaper is flame retardant and could one day help prevent fires on aircraft, ships and other structures. Its strength-to-weight ratio might also prove ideal when mak- ing protective gear, including helmets and body armor, for the military and police, as well as create improved, more comfort- able prosthetics for wounded veterans. Such features explain why the US Air Force and companies including Raytheon and Lockheed Martin have been investing in R&D efforts aimed at getting the material to fulfill its promise. Florida State University’s High-Performance Materials Insti- tute (HPMI; Tallahassee), where C60
co-discoverer and Nobel
Laureate Harold Kroto serves as senior science advisor—is paving the way when it comes to narrowing the gap between research and the practical use of buckypaper. Nobel Laure-
ate Richard Smalley first produced buckypaper during the 1990s by filtering a nanotube suspension in order to prepare samples for various tests. HPMI has spent the past several years building upon this work, making buckypapers larger and more multifunctional for composite fabrication and achieving several patents for its efforts.
Composites Dominate in Aero Materials Research
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While research on buckypaper continues, other materials also have the aerospace industry’s attention. Titanium, aluminum and high-nickel alloys such as Inconel will continue to hold interest, but the lion’s share of aerospace materials-related R&D is being done with composites, according to George N. Bullen, president and CEO of Smart Blades Inc. (Oxnard, CA). “By far, the largest investment in change to materials, materials baselines, and materials processes has been in composite materials,” Bullen recently told ME. He noted four primary areas where the next stage of incorporation can become cost effective to leverage the advan- tages of composite structures into large aero structures: Elimination of the autoclave for the cure of autoclave-cured materi- als. One method recently demonstrated successfully is In-A-Bag cure or degassing cure. If large composite structures can be cured using high-strength autoclave cure materials, out of the autoclave, then the cost, complexity and limitations of installing and operating an autoclave would be eliminated in the manufacturing process. Another approach is to bond large structures including substruc- tures into a single unified piece of aero-substructure. If bonding together of large skins and a substructure can be achieved that result in the same high-strength properties of a fastened aero-substructure, then significant cost and complexity would be reduced in the manufacturing process. There are currently major efforts to achieve this goal. If large unified structures can be achieved out of the autoclave, then methods and machines need to be and are being developed that can lay down large quantities of time-sensitive materials. When large structures are manufactured using composites, tooling and material handling become challenges, which are being addressed, and will in the near future migrate into the manufacturing process. InSitu inspection, test, and evaluation systems for large compos- ites structures are under development. Small structures currently made by hand are moved to the inspection areas for review after fabrication. As structures grow, they may be beyond the capability of factories to move to inspection machines.