Obtaining and characterization of the alumina-zirconia nanocomposite

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Obtaining and characterization of the alumina-zirconia nanocomposite Eliria M. J. A. Pallone1, Kátia L. Silva2, Roberto Tomasi3, Vania T. Hernandes4 and Cecilia Zavaglia2 1

Ciências Básicas, Universidade de São Paulo, Pirassununga, São Paulo, Brazil;

2

Engenharia Mecanica, UNICAMP, Campinas, São Paulo, Brazil;

3

Engenharia de Materiais, UFSCar, São Carlos, São Paulo, Brazil;

4

IPEN, São Paulo, São Paulo, Brazil.

ABSTRACT Ceramics of alumina of high density and purity can have a broad application area due to the combination of the excellent properties such as resistance to corrosion, good biocompatibility, and high resistance to wear and moderate mechanical resistance. But its low fracture toughness limits its range of applications. One possibility of improvement in the properties of these materials might be in the use of nanometric inclusions of ZrO2 into the matrix of Al2O3. The aim of this paper was to obtain and characterize the nanocomposites of alumina containing 0, 5, 10, 15 and 30 vol% of nanometric zirconium, seeking improvements in the mechanical properties and its comparison with values found for the matrix without the inclusion. For that, nanometric particles of ZrO2 were added into the matrix of alumina in the different proportions, using mixture of suspensions. The samples of alumina and nanocomposites of alumina-zirconium were physically, microstructurally and mechanically characterized. The results obtained, showed the efficiency of the used process, obtaining a good dispersion of the particles of zirconium in the matrix of alumina. The adding of up to 15vol% nanometric zirconium in the matrix of alumina promoted an increase in the values of the mechanical properties when compared with alumina. For the nanocomposites containing 30vol%, a good dispersion of the zirconium inclusions did not happen, leading to inferior values in the measured properties.

INTRODUCTION Alumina ceramics of high density and high purity may have a large area of application due to the combination of excellent properties as corrosion resistance, good biocompatibility and high resistance to wear and moderate mechanical strength. However its low fracture toughness limits its range of applications. A possibility to improve the properties of these materials may be in the use of nanometric inclusions of ZrO2 in Al2O3 matrix[1-2].

The great interest in ceramic nanocomposites was aroused after the pioneering work performed by Niihara et al [3-7]. On this paper studies the alumina nanocomposites containing 5vol% of nanometric inclusions of silicon carbide have increased the up to 300% in flexural strength and 40% in fracture toughness when compared with the values of alumina. In subsequent investigations, carried out by other researchers, we could not reproduce the high gain levels on the mechanical properties, although there is a positive consensus on the effect of addition of nano-sized SiC particles in alumina [8-14]. The difficulty in obtaining results similar to the results reported by Niihara et al [37] to explain the m