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Title: Three-dimensional machining of carbon nanotube forests using water-assisted scanning electron microscope processing

We demonstrate that vertically aligned carbon nanotubes (CNTs) can be precisely machined in a low pressure water vapor ambient using the electron beam of an environmental scanning electron microscope. The electron beam locally damages the irradiated regions of the CNT forest and also dissociates the water vapor molecules into reactive species including hydroxyl radicals. These species then locally oxidize the damaged region of the CNTs. The technique offers material removal capabilities ranging from selected CNTs to hundreds of cubic microns. We study how the material removal rate is influenced by the acceleration voltage, beam current, dwell time, operating pressure, and CNT orientation. Milled cuts with depths between 0–100 microns are generated, corresponding to a material removal rate of up to 20.1 μm{sup 3}/min. The technique produces little carbon residue and does not disturb the native morphology of the CNT network. Finally, we demonstrate direct machining of pyramidal surfaces and re-entrant cuts to create freestanding geometries.
Authors:
;  [1] ; ;  [2] ;  [3] ;  [4] ;  [3]
  1. Department of Mechanical and Aerospace Engineering, University of Missouri, Columbia, Missouri 65211 (United States)
  2. Department of Mechanical Engineering and Laboratory for Manufacturing and Productivity, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)
  3. Materials and Manufacturing Directorate, AFRL/RX, Air Force Research Lab, Ohio 45433 (United States)
  4. (United States)
Publication Date:
OSTI Identifier:
22482217
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 107; Journal Issue: 14; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; BEAM CURRENTS; CARBON NANOTUBES; ELECTRON BEAMS; HYDROXYL RADICALS; IRRADIATION; MACHINING; MOLECULES; MORPHOLOGY; ORIENTATION; SCANNING ELECTRON MICROSCOPY; WATER; WATER VAPOR