Enhanced Electrical and Mechanical Properties of Alumina-Based TiC Composites by Spark Plasma Sintering

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DESIGNING of high-performance engineering materials through identification of best combination, orientation, and distribution of second phase in a pristine matrix has gained renewed interest recently.[1–3] Alumina is one of the most versatile ceramic material that possesses excellent physical properties such as low density, high hardness, superior chemical inertness, good thermal stability, excellent electrical insulation, and optical properties. These characteristics make it attractive for a wide range of applications including wear-resistant parts, bioceramics, electrical/thermal insulators, cutting tools, energy efficient sliding systems, and energy efficient lamp envelopes and windows.[4–6] For high-temperature applications, alumina can be used in the construction of gas turbine engines in order to improve their thermal cycle efficiency.[7] Furthermore, alumina is a perfect insulator, and if its structural properties can be integrated with high electrical conductivity, then its spectrum of applications may spread over functional materials which include heating elements, electrical igniters, antistatic, electromagnetic shielding effectiveness of electronic components, electrode for fuel cell, etc.[8,9] However, as an intrinsic property, low fracture toughness is the bane of alumina-based materials which may cause sudden failure during their applications. Therefore, the performance of alumina ceramics is limited due to their high value of KALEEM AHMAD, Visiting Scholar, is with the State Key Lab of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084, P.R. China, and also Assistant Professor, with the Sustainable Energy Technologies Center, King Saud University, Riyadh 11421, Saudi Arabia. Contact e-mail: [email protected] WEI PAN, Professor, is with the State Key Lab of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University. Manuscript submitted March 20, 2014. Article published online September 12, 2014 METALLURGICAL AND MATERIALS TRANSACTIONS A

brittleness especially in severe environments. In addition, some structural applications of alumina in complex geometries require contact-less machining as the conventional method for machining is expensive and cumbersome.[10] Therefore, the high electrical conductivity is required to make it possible to machine it using electro discharging machining (EDM) to fabricate complex prototypes.[10] Titanium carbide (TiC) has emerged recently as a hightech material in composites due to its remarkable functional properties.[9,11] This includes high Young’s modulus, high Vickers hardness, high resistance to corrosion, oxidation, abrasions, good thermal conductivity, thermal shock resistance, and high electrical conductivity.[12] These properties of TiC make it an ideal candidate to improve the structural and functional properties of alumina matrix by incorporating TiC as a second phase. In addition, the high electrical conductivity of TiC has already been found