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ORIGINAL ARTICLE

Optimization of fracture behavior of alumina/silicon carbide nano ceramic Naser Kordani • Ali Sadough vanini Ali Asadi • Amin Jabbari

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Received: 23 June 2012 / Accepted: 21 September 2012 Ó Springer-Verlag London 2012

Abstract Improving fracture performance and sintering procedure of alumina/silicon carbide nano ceramic is considered. To do this, some experimental variables such as sintering conditions and silicon carbide volume fraction were optimized. In this study, several tests were conducted on the nano ceramic samples which prepared in different conditions to achieve the best fracture properties. The main concern is the properties which are important against projectile impacts. Flexural strength, fracture toughness, Vickers hardness, and energy dissipation factor for different samples were measured, and optimum sintering conditions were obtained. Keywords Alumina/silicon carbide  Nano ceramic  Sintering  Particle dispersion  Fracture properties

1 Introduction The low density, high hardness, and strength of nano ceramic materials encouraged many researchers that they have reported on the subject of these materials [1]. To overcome the brittleness of conventional ceramics, new techniques for creating the nano ceramics have been N. Kordani (&)  A. S. vanini  A. Asadi  A. Jabbari Department of Mechanical Engineering, Amirkabir University of Technology, Tehran, Iran e-mail: [email protected] A. S. vanini e-mail: [email protected] A. Asadi e-mail: [email protected] A. Jabbari e-mail: [email protected]

developed. One of the techniques to improve the strength of ceramics such as alumina is dispersion of nanoparticles in the matrix. Material design significantly improved strength of the material by dispersing second phase nanosize particles. Despite common composites of which second phase particles were mainly located on the boundaries, Silicon carbide particles were mainly located within alumina matrix grains because of the transformation of alumina from the gamma phase to the alpha phase as shown by Wang et al. [2]. Difference of thermal expansion between matrix and silicon carbide particles produces significant improvement in mechanical properties of nano ceramic, especially fracture toughness of the material. This is done by producing nanocracks in matrix material. These nanocracks cause the growth of the frontal process zone size ahead of a crack tip and improve the fracture toughness of the material as shown by Seong-Min and Hideo [3]. A theoretical model for investigating thermal expansions anisotropy of the alumina matrix and silicon carbide particles showed that high strength could be achieved because of the residual micro stresses. Such micro stresses are distributed in the lattice rather than being localized at the grain boundaries as shown by Pezzoti and Muller [4]. Medvedovski [5] showed that satisfactory high-speed impact performance of the alumina-mullite ceramics can be explained by their high impact energy dissipation ability. Therefore, energy dispersion (D) i