Dispersion of Carbon Nanotubes in Alumina using a Novel Mixing Technique and Spark Plasma Sintering of the Nanocomposites with Improved Fracture Toughness Nabi Bakhsh 1,a* , Fazal Ahmad Khalid 1,b , Abbas Saeed Hakeem 2,c , Tahar Laoui 2,3,d 1 Faculty of Materials Science and Engineering, GIK Institute of Engineering Sciences and Technology, Topi, Swabi, KPK, Pakistan 2 Centre of Excellence in Nanotechnology, King Fahd University of Petroleum and Minerals, Dhahran 31261, Kingdom of Saudi Arabia 3 Mechanical Engineering Department, King Fahd University of Petroleum and Minerals, Dhahran 31261, Kingdom of Saudi Arabia a khoja72@gmail.com, b khalid@giki.edu.pk, c ashakeem@kfupm.edu.sa, d tlaoui@kfupm.edu.sa Keyword: SPS, Nanocomposites, Mechanical characterization, Fracture toughness Abstract. The present study emphasizes on the fabrication of carbon nanotubes (CNTs) reinforced alumina nanocomposites for structural applications. A new technique for the mixing and dispersion of CNTs in alumina powder was employed. Spark plasma sintering (SPS) technique was used for the fabrication of nanocomposites with varying amounts of as-received CNTs (1, 2 and 3 weight %) in alumina matrix. Densification behavior, hardness and fracture toughness of the nanocomposites were studied. A comparison of mechanical properties of the desired nanocomposites was presented. An improvement in fracture toughness of approximately 14% at 1 wt% CNT-alumina nanocomposite over monolithic alumina compacts was observed due to better dispersion of CNTs in alumina matrix that ultimately helped in grain growth suppression to provide finer grain in the nanocomposites. The fractured surfaces also revealed the presence of CNTs bridging and pull out that aided in the improvement of mechanical properties. The synthesized samples were characterized using field emission scanning electron microscopy, X-ray diffraction, Raman spectroscopy, densification, Vickers hardness testing and fracture toughness measurements. Introduction Innovative materials and processing techniques have unlocked numerous prospects for the fabrication of advanced structural materials for different high performance applications. Therefore, nanostructured and nanophase materials are attracting a lot of attention due to their potential applications in the fields of ceramics, optics, electronics, nanocomposites [1]. Nanocomposites not only have overcome the limitations of monolithics and microcomposites, but also pose serious challenges in their synthesis and control of stoichiometry [2]. The discovery of CNTs has opened up a new era in the field of nanotechnology. Current research is mainly focused on the synthesis and characterization of CNT-reinforced polymers, metals, or ceramic matrix nanocomposites [2-4]. Uniform dispersion of CNTs in the matrix is indispensable for predictable properties and optimal performance of nanocomposites. Different chemical and/or physical approaches have been employed to de-agglomerate the CNTs that are bonded with strong Van der Waal’s forces [5-9]. Ceramic materials are used in high temperature applications due to their hardness, wear resistance and chemical inertness [10, 11]. Extensive research has been carried out to enhance the mechanical properties of alumina-based composites using different reinforcements and sintering techniques that include hot pressing, hot isostatic pressing [10, 12, 13]. However, SPS is widely being used for the consolidation and modification in the microstructure of CNT-ceramic nanocomposites. The reaction kinetics between CNT and ceramics, grain growth and densification Advances in Science and Technology Vol. 89 (2014) pp 76-81 Submitted: 19.05.2014 Online available since 2014/Oct/31 at www.scientific.net Accepted: 03.07.2014 © (2014) Trans Tech Publications, Switzerland doi:10.4028/www.scientific.net/AST.89.76 All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of TTP, www.ttp.net. (ID: 212.26.2.101-02/11/14,06:44:04)