@article{4522db0aea814c7f9efcdca36e34ef04,
title = "Enhanced thermal stability of carbon nanotubes by plasma surface modification in Al2O3 composites",
abstract = "A plasma polymerization method was employed to deposit an ultrathin pyrrole film of 3 nm onto the surfaces of single wall carbon nanotubes (SWCNTs) and Al2 O3 nanoparticles for developing high-strength nanocomposites. The surfaces of plasma coated SWCNTs and Al2 O3 nanoparticles were studied by high resolution transmission electron microscopy (TEM) and time-of-flight secondary ion mass spectroscopy. After sintering the SWCNTs- Al2 O3 composites at different temperatures (maximum of 1200 °C), the thermal stability of plasma-coated SWCNTs was significantly increased, compared to their uncoated counterparts. After hot-press sintering, the SWCNTs without plasma coating were essentially decomposed into amorphous clusters in the composites, leading to degraded mechanical properties. However, under the same sintering conditions, the plasma surface modified SWCNTs were well preserved and distributed in the composite matrices. The effects of plasma surface coating on the thermal stability of SWCNTs and mechanical behavior of the nanocomposites are discussed.",
author = "Hoonsung Cho and Donglu Shi and Yan Guo and Jie Lian and Zhifeng Ren and Bed Poudel and Yi Song and Abot, {Jandro L.} and Dileep Singh and Jules Routbort and Lumin Wang and Ewing, {Rodney C.}",
note = "Funding Information: The authors are grateful to Chemat Technologies for the support under a U.S. Air Force SBIR grant. The TEM analyses were conducted at the Electron Microbeam analysis Laboratory at the University of Michigan and support supported by the Office of Basic Energy Sciences of the U.S. Department of Energy through Grant No. DE-FG02-97ER45656. FIG. 1. (a) and (b) Bright-field TEM images of the plasma pyrrole coated SWCNTs and Al 2 O 3 nanoparticles. FIG. 2. (a) Positive TOF-SIMS spectra of uncoated and (b) positive TOF-SIMS spectra of pyrrole coated nanoparticles. FIG. 3. SEM images showing (a) cross section of SWCNTs- Al 2 O 3 composite without plasma coating, and (b) cross section of SWCNTs- Al 2 O 3 composite with plasma coating. FIG. 4. Bright-field TEM images of the SWCNTs / Al 2 O 3 composites, (a) sintered at 1000 ° C under ambient pressure, and (b) hot-press sintered at 1200 ° C . FIG. 5. Bright-field TEM image of the SWCNTs / Al 2 O 3 composite, hot-press sintered at 1200 ° C , showing well preserved SWCNTs entangled between the alumina grains. FIG. 6. Stress-strain curves, obtained from the compressive mode, of the coated and uncoated SWCNTs / Al 2 O 3 composites with 7 wt % SWCNTs. FIG. 7. Stress-strain curves, obtained from the flexure mode, of the coated and uncoated SWCNTs / Al 2 O 3 composites with 7 wt % SWCNTs. FIG. 8. Bright-field TEM images of the SWCNTs / Al 2 O 3 composites sintered at 1000 ° C under ambient pressure, showing (a) plasma coated SWCNTs with well preserved morphology and are connected to the alumina grains; (b) severely oxidized and shortened SWCNTs without plasma coating; (c) the SWCNTs embedded in the Al 2 O 3 grain with well preserved crystal lattices due to protection of plasma coating, and (d) SWCNTs without coating are severely oxidized and reduced to the amorphous structure. ",
year = "2008",
doi = "10.1063/1.2985915",
language = "English (US)",
volume = "104",
journal = "Journal of Applied Physics",
issn = "0021-8979",
publisher = "American Institute of Physics",
number = "7",
}