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Influence of Ta2O5 Doping on the Microstructure, Physical and Mechanical Properties of α-Alumina Ceramics
S.M. Naga1, A.M. Hassan2, M. Awaad1, F. Bondioli3
1 National Research Center, Ceramics Dept., El-Bohous Str., 12622- Cairo, Egypt
2 Zagazig Uni., Faculty of Engineering, Materials Engineering Dept., 44519 – Zagazig, Egypt
3 Dipartimento di Ingegneria "Enzo Ferrari" Università di Modena e Reggio Emilia Via Vignolese 905 – 41125 Modena (I)
received July 13, 2013, received in revised form August 26, 2013, accepted October 27, 2013
Vol. 4, No. 4, Pages 187-192 DOI: 10.4416/JCST2013-00017
Abstract
The effects of Ta2O5 addition on the densification behavior, microstructure and mechanical properties of Ta2O5-doped alumina ceramics were investigated. The Ta2O5 addition to the alumina matrix was varied from 0.25 wt% to 0.75 wt%. In order to optimize the sintering temperature, the powders of each composition were uniaxially pressed at 220 MPa into discs and rectangular bars, which were then pressureless-sintered at a temperature ranging from 1500 to 1650 °C for 1 h. The phase constitution and microstructure of the sintered ceramic bodies were characterized with an X-ray diffractometer and a scanning electron microscope. The mechanical properties of the ceramic bodies were evaluated based on their Vickers hardness (HV1), bending strength and fracture toughness tests. It was found that Ta2O5 addition improved densification, reinforcing and toughening the bodies. The maximum bending strength, fracture toughness and Vickers hardness of the bodies with 0.75 wt% Ta2O5 were 53.4, 43.8 and 33.4 % higher than that of pure alumina.
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Keywords
Doping, alumina, tantala, microstructure, mechanical properties.
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