Rao R.,Air Force Research Lab |
Rao R.,Honda Research Institute United States Inc. |
Liptak D.,Air Force Research Lab |
Liptak D.,UES, Inc. |
And 3 more authors.
Nature Materials | Year: 2012
Chiral-selective growth of single-walled carbon nanotubes (SWNTs) remains a great challenge that hinders their use in applications such as electronics and medicine. Recent experimental and theoretical reports have begun to address this problem by suggesting that selectivity may be achieved during nucleation by changing the catalyst composition or structure. Nevertheless, to establish a rational basis for chiral-selective synthesis, the underlying mechanisms governing nucleation, growth, and termination of SWNTs must be better understood. To this end, we report the first measurements of growth rates of individual SWNTs through in situ Raman spectroscopy and correlate them with their chiral angles. Our results show that the growth rates are directly proportional to the chiral angles, in agreement with recent theoretical predictions. Importantly, the evidence singles out the growth stage as responsible for the chiral distribution-distinct from nucleation and termination which might also affect the final product distribution. Our results suggest a route to chiral-selective synthesis of SWNTs through rational synthetic design strategies based on kinetic control. © 2012 Macmillan Publishers Limited. All rights reserved. Source
UES, Inc. | Date: 2014-03-10
A photoconductive semiconductor switch comprising a photoconductive GaAs substrate having a pair of spaced metal contacts on a surface thereof, the spaced metal contacts opposite ends of a switching gap, the switching gap having a plurality of lateral current flow preventing channels therein, the channels being formed by ion implantation of the GaAs substrate in the channels.
SKF Corporation, Midwest Thermal Vac Inc. and UES, Inc. | Date: 2012-05-31
A method for producing a case-hardened martensitic stainless steel article includes: providing an article comprised, at least in part, of a martensitic stainless steel, carburizing the article within a temperature range of 1625 F.-1680 F. (885 C.-916 C.), and then carbo-nitriding the article within a temperature range of 1575 F.-1625 F. (857 C.-885 C.). An article, such as a bearing ring, comprising such a case-hardened martensitic stainless steel is also disclosed.
UES, Inc. | Date: 2011-10-04
The present invention discloses a high strength AlZnMgCu (7000 series) alloy that can be cast, the cast alloy having a tensile strength of at least 500 megapascals (MPa) and 4% elongation. The cast alloy composition can include about 5.5-9.0 weight percent (wt. %) of zinc, 2.0-3.5 wt. % of magnesium, 0.1-0.5 wt. % scandium, 0.05-0.20 wt. % zirconium, 0.5-3.0 wt. % copper, 0.10-0.45 wt. % manganese, 0.01-0.35 wt. % iron, 0.01-0.20 wt. % silicon with a balance of aluminum and possible casting impurities. The alloy also has good fluidity comparable to high silicon cast aluminum alloys and components can be manufactured using direct chill casting, sand casting, and/or sand casting under high pressure.
Agency: Department of Defense | Branch: Air Force | Program: SBIR | Phase: Phase II | Award Amount: 412.74K | Year: 2016
ABSTRACT: This Phase II SBIR program involves a novel process to produce new hybrid ultra-high temperature (UHTC) ceramic composites that can survive hypersonic flight conditions. The new process will produce a very unique grain and graded microstructure that can offer high strength (> 100 kpsi), high fracture toughness (> 10 MPam), high thermal shock resistance, and high oxidation resistance over 2000oC. Thus, the new hybrid composites can serve as leading edges for hypersonic applications. Spark plasma sintering or hot-pressing will be used as a means for densification. In addition, near-net shape fabrication will be explored to produce sharp leading edges during the Phase II program.; BENEFIT: The successful completion of the Phase II program will provide the foundation needed to produce oxidation and thermal shock resistant UHTCs. Examples of primary applications are leading edges for hypersonic vehicles, as well as solid rocket motors (SRM) for various DoD applications including all rocket nozzles, and other ground-based missile interceptors.