High Temperature Deformation of Dual Phase Alumina-Zirconia Composites

Abstract

The development of muliphase ceramic composites may result in materials with enhanced properties compared with their single phase constituents. Recently, colloidal powder processing and stress assisted sintering have been developed as techniques to produce fully dense monolithic ceramics and ceramic composites which often are stronger and more reliable than conventionally fabricated ceramics. During stress assisted sintering techniques such as sinter forging or hot pressing, deformation occurs concurrently with densification. The results on an investigation of the effect of second phase additions of alumina on the high temperature deformation and densification behavior of a yttria-stabilized zirconia are reported. First, compression creep experiments were conducted on a fully dense alumina-zirconia composite to characterize the deformation behavior over a wide range of experimental conditions. Second, sinter forging experiments were conducted on varying compositions in the alumina-zirconia system. It was demonstrated that the mechanism associated with deformation of the composites is independent of composition for alumina weight fractions up to 40%. The deformation and densification rates increased dramatically when small amounts of alumina were added to zirconia, whereas the rates decreased as the alumina content was increased from 7 wt%.