Abstract: A spun fiber of carbon nanotubes is exposed to ion irradiation. The irradiation exposure increases the specific strength of the spun fiber.

Abstract: A structure for preparing an substantially aligned array of carbon nanotubes include a substrate having a first side and a second side, a buffer layer on the first side of the substrate, a catalyst on the buffer layer, and a plurality of channels through the structure for allowing a gaseous carbon source to enter the substrate at the second side and flow through the structure to the catalyst. After preparing the array, a fiber of carbon nanotubes may be spun from the array. Prior to spinning, the array can be immersed in a polymer solution. After spinning, the polymer can be cured.

Abstract: An array of carbon nanotubes is prepared by exposing a catalyst structure to a carbon nanotube precursor. Embodiment catalyst structures include one or more trenches, channels, or a combination of trenches and channels. A system for preparing the array includes a heated surface for heating the catalyst structure and a cooling portion that cools gas above the catalyst structure. The system heats the catalyst structure so that the interaction between the precursor and the catalyst structure results in the formation of an array of carbon nanotubes on the catalyst structure, and cools the gas near the catalyst structure and also cools any carbon nanotubes that form on the catalyst structure to prevent or at least minimize the formation of amorphous carbon. Arrays thus formed may be used for spinning fibers of carbon nanotubes.

Abstract: A fiber of carbon nanotubes was prepared by a wet-spinning method involving drawing carbon nanotubes away from a substantially aligned, supported array of carbon nanotubes to form a ribbon, wetting the ribbon with a liquid, and spinning a fiber from the wetted ribbon. The liquid can be a polymer solution and after forming the fiber, the polymer can be cured. The resulting fiber has a higher tensile strength and higher conductivity compared to dry-spun fibers and to wet-spun fibers prepared by other methods.

Abstract: A fiber of carbon nanotubes was prepared by a wet-spinning method involving drawing carbon nanotubes away from a substantially aligned, supported array of carbon nanotubes to form a ribbon, wetting the ribbon with a liquid, and spinning a fiber from the wetted ribbon. The liquid can be a polymer solution and after forming the fiber, the polymer can be cured. The resulting fiber has a higher tensile strength and higher conductivity compared to dry-spun fibers and to wet-spun fibers prepared by other methods.

Abstract: In a method for fabricating a carbon nanotube (CNT) composite, an array of CNTs is provided. A CNT ribbon is pulled from the array and wound on a rotating mandrel. A polymer solution is applied to the ribbon to form a CNT composite laminate. The CNTs in the ribbon may be substantially aligned in a single direction. The ribbon may be attached to the mandrel such that the ribbon may be wound on the mandrel as the mandrel rotates. A CNT composite is provided that may include a polymer integrated with long, substantially straight CNTs that are highly aligned in a single direction. An apparatus for fabricating a CNT composite is provided that may include a rotatable mandrel and a spray gun. The spray gun may be configured for spraying a polymer solution on the CNT ribbon as the CNT ribbon is taken up on the rotating mandrel.

Abstract: Chromatic materials such as polydiacetylene change color in response to a wide variety of environmental stimuli including changes in temperature, pH and chemical or mechanical stress, and have been extensively explored as sensing devices. Here is reported the facile synthesis of carbon nanotube/polydiacetylene nanocomposite fibers which rapidly and reversibly respond to electrical current, with the resulting color change being readily observable with the naked eye. These composite fibers also chromatically respond to a broad spectrum of other stimulations: for example, they exhibit rapid and reversible stress-induced chromatism with negligible elongation. Nanotube/polydiacetylene nanocomposite fibers could have various applications in sensing.

Abstract: Fibers are spun from a supported array of nanotubes. Fibers are spun using a spinning shaft with, for example, a hook shaped end that contacts the supported nanotubes and twists some of them around each other to begin the fiber. As the twisted nanotubes detach from the support, the shaft moves away from and along the supported array in a controlled direction and at a controlled speed as it spins to twist and detach additional nanotubes from the support and extend the length of the fiber. If the array is pretreated with a dilute polymer solution, excess solution is squeezed out of the growing fiber during spinning, and the polymer may be cured at elevated temperature to provide a strong nanotube composite fiber.

Abstract: A spun fiber of carbon nanotubes is exposed to ion irradiation. The irradiation exposure increases the specific strength of the spun fiber.

Abstract: A method for preparing a nanostructured aluminum alloy involves heating an aluminum alloy workpiece at temperature sufficient to produce a single phase coarse grained aluminum alloy, then refining the grain size of the workpiece at a temperature at or below room temperature, and then aging the workpiece to precipitate second phase particles in the nanosized grains of the workpiece that increase the ductility without decreasing the strength of the workpiece.

Abstract: A fiber of carbon nanotubes was prepared by a wet-spinning method involving drawing carbon nanotubes away from a substantially aligned, supported array of carbon nanotubes to form a ribbon, wetting the ribbon with a liquid, and spinning a fiber from the wetted ribbon. The liquid can be a polymer solution and after forming the fiber, the polymer can be cured. The resulting fiber has a higher tensile strength and higher conductivity compared to dry-spun fibers and to wet-spun fibers prepared by other methods.

Abstract: A structure for preparing an substantially aligned array of carbon nanotubes include a substrate having a first side and a second side, a buffer layer on the first side of the substrate, a catalyst on the buffer layer, and a plurality of channels through the structure for allowing a gaseous carbon source to enter the substrate at the second side and flow through the structure to the catalyst. After preparing the array, a fiber of carbon nanotubes may be spun from the array. Prior to spinning, the array can be immersed in a polymer solution. After spinning, the polymer can be cured.

Abstract: A method for preparing a nanostructured aluminum alloy involves heating an aluminum alloy workpiece at temperature sufficient to produce a single phase coarse grained aluminum alloy, then refining the grain size of the workpiece at a temperature at or below room temperature, and then aging the workpiece to precipitate second phase particles in the nanosized grains of the workpiece that increase the ductility without decreasing the strength of the workpiece.

Abstract: An array of carbon nanotubes is prepared by exposing a catalyst structure to a carbon nanotube precursor. Embodiment catalyst structures include one or more trenches, channels, or a combination of trenches and channels. A system for preparing the array includes a heated surface for heating the catalyst structure and a cooling portion that cools gas above the catalyst structure. The system heats the catalyst structure so that the interaction between the precursor and the catalyst structure results in the formation of an array of carbon nanotubes on the catalyst structure, and cools the gas near the catalyst structure and also cools any carbon nanotubes that form on the catalyst structure to prevent or at least minimize the formation of amorphous carbon. Arrays thus formed may be used for spinning fibers of carbon nanotubes.

Abstract: An apparatus that continuously processes a metal workpiece without substantially altering its cross section includes a wheel member having an endless circumferential groove, and a stationary constraint die that surrounds the wheel member, covers most of the length of the groove, and forms a passageway with the groove. The passageway has a rectangular shaped cross section. An abutment member projects from the die into the groove and blocks one end of the passageway. The wheel member rotates relative to the die in the direction toward the abutment member. An output channel in the die adjacent the abutment member has substantially the same cross section as the passageway. A metal workpiece is fed through an input channel into the passageway and carried in the groove by frictional drag in the direction towards the abutment member, and is extruded through the output channel without any substantial change in cross section.

Abstract: A process is disclosed of increasing the critical current density in a superconducting magnesium boride wire by heating a magnesium diboride precursor wire under isostatic pressure in an inert atmosphere at temperatures and for time sufficient to form a superconducting magnesium boride wire characterized as having a higher critical current density than a superconducting magnesium boride wire heated under the same temperature conditions in the absence of isostatic pressing.

Abstract: A process of preparing superconducting magnesium diboride powder by heating an admixture of solid magnesium and amorphous boron powder or pellet under an inert atmosphere in a Mg:B ratio of greater than about 0.6:1 at temperatures and for time sufficient to form said superconducting magnesium diboride. The process can further include exposure to residual oxygen at high synthesis temperatures followed by slow cooling. In the cooling process oxygen atoms dissolved into MgB2 segregated to form nanometer-sized coherent Mg(B,O) precipitates in the MgB2 matrix, which can act as flux pinning centers.

Abstract: A method of refining the grain structure and improving the hardness and strength properties of a metal or metal alloy workpiece is disclosed. The workpiece is subjected to forces that corrugate and then straighten the workpiece. These steps are repeated until an ultrafine-grained product having improved hardness and strength is produced.

Abstract: We disclose ultrafine-grained titanium. A coarse-grained titanium billet is subjected to multiple extrusions through a preheated equal channel angular extrusion (ECAE) die, with billet rotation between subsequent extrusions. The resulting billet is cold processed by cold rolling and/or cold extrusion, with optional annealing. The resulting ultrafine-grained titanium has greatly improved mechanical properties and is used to make medical implants.

Abstract: A method of refining the grain structure and improving the hardness and strength properties of a metal or metal alloy workpiece is disclosed. The workpiece is subjected to forces that corrugate and then straighten the workpiece. These steps are repeated until an ultrafine-grained product having improved hardness and strength is produced.