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Title: Magnesia tuned multi-walled carbon nanotubes–reinforced alumina nanocomposites

Magnesia tuned alumina ceramic nanocomposites, reinforced with multi-walled carbon nanotubes, were condensed using pressureless and hot-press sintering processes. Densification, microstructure and mechanical properties of the produced nanocomposites were meticulously investigated. Electron microscopy studies revealed the homogenous carbon nanotube dispersion within the alumina matrix and confirmed the retention of carbon nanotubes' distinctive tubular morphology and nanoscale features during the extreme mixing/sintering processes. Pressureless sintered nanocomposites showed meagre mechanical responses due to the poorly-integrated microstructures with a slight improvement upon magnesia addition. Conversely, both the magnesia addition and application of hot-press sintering technique resulted in the nanocomposite formation with near-theoretical densities (~ 99%), well-integrated microstructures and superior mechanical properties. Hot-press sintered nanocomposites incorporating 300 and 600 ppm magnesia exhibited an increase in hardness (10 and 11%), flexural strength (5 and 10%) and fracture toughness (15 and 20%) with respect to similar magnesia-free samples. Compared to monolithic alumina, a decent rise in fracture toughness (37%), flexural strength (22%) and hardness (20%) was observed in the hot-press sintered nanocomposites tuned with merely 600 ppm magnesia. Mechanically superior hot-press sintered magnesia tailored nanocomposites are attractive for several load-bearing structural applications. - Highlights: • MgO tailored Al{sub 2}O{sub 3}–2 wt.% CNT nanocomposites are presented. • Themore » role of MgO and sintering on nanocomposite structures and properties was studied. • Well-dispersed CNTs maintained their morphology/structure after harsh sintering. • Hot-pressing and MgO led nanocomposites to higher properties/unified structures. • MgO tuned composites showed higher toughness (37%) and strength (22%) than Al{sub 2}O{sub 3}.« less
Authors:
 [1] ; ;  [1] ;  [2] ;  [3] ;  [4]
  1. Center of Excellence for Research in Engineering Materials, Advanced Manufacturing Institute, King Saud University, P.O. Box. 800, Riyadh 11421 (Saudi Arabia)
  2. Division of Materials, Mechanics and Structure, Faculty of Engineering, University of Nottingham, University Park, NG7 2RD (United Kingdom)
  3. Department of Materials Science and Engineering, University of Delaware, Newark, DE 19716 (United States)
  4. College of Engineering, Mathematics and Physical Sciences, University of Exeter, Exeter EX4 4QF (United Kingdom)
Publication Date:
OSTI Identifier:
22476018
Resource Type:
Journal Article
Resource Relation:
Journal Name: Materials Characterization; Journal Volume: 99; Other Information: Copyright (c) 2014 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
77 NANOSCIENCE AND NANOTECHNOLOGY; ALUMINIUM OXIDES; CARBON NANOTUBES; CERAMICS; DENSITY; DISPERSIONS; ELECTRON MICROSCOPY; MAGNESIUM OXIDES; MICROSTRUCTURE; NANOCOMPOSITES; NANOSTRUCTURES; RETENTION