Effect of Al<sub>2</sub>O<sub>3</sub> Addition on Microstructure, Thermal Expansion and Mechanical Properties of Ta<sub>2</sub>O<sub>5</sub> Ceramics

Abstract

The Ta 2 O 5 -based ceramics were prepared by dry pressing/sintering technique using Ta 2 O 5 and Al 2 O 3 as the starting materials. The present work investigated the effect of alumina (Al 2 O 3 ) additions on the composition, microstructure, thermal expansion coefficient (TEC) and bending strength of Ta 2 O 5 ceramics. The thermal expansion of the samples was measured by the dilatometry method. It was found that Al 2 O 3 additions can effectively inhibit the β to α phase transformation in Ta 2 O 5 ceramics. Orthorhombic AlTaO 4 as the minor phase formed when 2.5 and 7.0 wt% Al 2 O 3 was added. The addition of Al 2 O 3 results in obvious change of TEC and an increase of bending strength. This work demonstrated that the addition of Al 2 O 3 is an effective way to modify the TEC and mechanical strength of Ta 2 O 5 ceramics.