Buckypaper: - Society of Manufacturing Engineers

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Aerospace MaterialsThis small-scale aircraft model demonstrates howbuckypaper allows lightning’s electrical chargeto flow around the plane and dissipate withoutcausing damage.Science-Fiction FeaturesBuckypaper is about 25-µm thick and madefrom CNT fibers about 1/50,000th the diameter ofa human hair. The nanotubes have atomic bondspowerful enough to make them twice as hard asdiamond. When sheets of buckypaper are stacked,the resulting composite material is 10 times lighterthan steel—but 250 times stronger. The implicationsfor aerostructures—increased payloads and improvedfuel efficiency—are tantalizing.Also, unlike conventional composite materials,buckypaper conducts electricity about as well assilicon and disperses heat like steel. Instead of the90 ManufacturingEngineeringMedia.com | March 2013
Aerospace Materialsmetal mesh currently used in the structure of the compositeaircraft to disperse lightning strikes, buckypaper, with itshigh current-carrying capacity, would allow lightning’s electricalcharge to flow around the plane and dissipate withoutcausing damage.Furthermore, buckypaper is flame retardant and could oneday help prevent fires on aircraft, ships and other structures.Its strength-to-weight ratio might also prove ideal when makingprotective gear, including helmets and body armor, for themilitary and police, as well as create improved, more comfortableprosthetics for wounded veterans. Such features explainwhy the US Air Force and companies including Raytheon andLockheed Martin have been investing in R&D efforts aimed atgetting the material to fulfill its promise.Florida State University’s High-Performance Materials Institute(HPMI; Tallahassee), where C 60co-discoverer and NobelLaureate Harold Kroto serves as senior science advisor—ispaving the way when it comes to narrowing the gap betweenresearch and the practical use of buckypaper. Nobel LaureateRichard Smalley first produced buckypaper during the1990s by filtering a nanotube suspension in order to preparesamples for various tests. HPMI has spent the past severalyears building upon this work, making buckypapers larger andmore multifunctional for composite fabrication and achievingseveral patents for its efforts.Composites Dominate inAero Materials ResearchWhile research on buckypaper continues, other materials also havethe aerospace industry’s attention. Titanium, aluminum and high-nickelalloys such as Inconel will continue to hold interest, but the lion’s shareof 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, materialsbaselines, and materials processes has been in composite materials,”Bullen recently told ME. He noted four primary areas where the nextstage of incorporation can become cost effective to leverage the advantagesof composite structures into large aero structures:Elimination of the autoclave for the cure of autoclave-cured materials.One method recently demonstrated successfully is In-A-Bag cureor degassing cure. If large composite structures can be cured usinghigh-strength autoclave cure materials, out of the autoclave, then thecost, complexity and limitations of installing and operating an autoclavewould be eliminated in the manufacturing process.Another approach is to bond large structures including substructuresinto a single unified piece of aero-substructure. If bondingtogether of large skins and a substructure can be achieved that result inthe same high-strength properties of a fastened aero-substructure, thensignificant cost and complexity would be reduced in the manufacturingprocess. 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 thatcan lay down large quantities of time-sensitive materials. When largestructures are manufactured using composites, tooling and materialhandling become challenges, which are being addressed, and will in thenear future migrate into the manufacturing process.InSitu inspection, test, and evaluation systems for large compositesstructures are under development. Small structures currently madeby hand are moved to the inspection areas for review after fabrication.As structures grow, they may be beyond the capability of factories tomove to inspection machines.92 ManufacturingEngineeringMedia.com | March 2013
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Buckypaper: - Society of Manufacturing Engineers

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