Preparation and Characterization of Nb₂O₅-Al₂O₃ System Ceramics with Different Al₂O₃ Additions

Abstract:

The Nb₂O₅-Al₂O₃ binary system ceramics were prepared by high temperature solid state reaction sintering, using Nb₂O₅ and Al₂O₃ micro powder as the raw materials. The samples were characterized by XRD, SEM, thermodilatometric analysis and mechanical strength measurement. The influences of Al₂O₃ content on the phase composition, microstructure, thermal expansion properties and bending strength were investigated. Results show the samples shows obvious changes in phase composition and microstructure with the addition of Al₂O₃ from 2.5% to 15%. The pure Nb₂O₅ ceramic is composed of monoclinic phase Nb₂O₅, while different monoclinic aluminum niobates were formed with different Al₂O₃ additions. Obvious microcracking can be observed for the samples without and with 2.5% and 7.5% Al₂O₃ additions. The addition of Al₂O₃ leads to significant increase of bending strength, and all the samples keep relatively low thermal expansion coefficient (TEC). The Nb₂O₅-Al₂O₃ binary system ceramics with ultra low TEC (0.55~0.86×10^-6°C^-1) and improved bending strength (50.4~70.6MPa) could be obtained with the addition of 7.5~15% Al₂O₃ when sintered at 1390°C for 2h.

• Periodical: Key Engineering Materials (Volume 544)
• Pages: 60-63
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.544.60
• Online since: March 2013
• Authors: Xiao Zhen Zhang, Jian Er Zhou, Yu Hua Jiang, Chun Rong Wu, Chuan Ying Lin
• Keywords: Alumina, Bending Strength, Low Expansion Ceramic, Niobium Pentaoxide, Thermal Expansion Coefficient

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