Preparation and characterization of an Al2O3-ZrO2 nanocomposite, Part I:: Powder synthesis and transformation behavior during fracture

An alumina-zirconia composite containing 5 mol% zirconia was prepared by following a wet interaction process in aqueous medium via the sol-gel route. The formed hydrogel which was aged for proper growth and orientation at room temperature, was then dried at a low temperature to minimize agglomeration. The sol-gel derived precursor powder was properly characterized through determination of surface area, particle size and thermal analysis. The sintering behavior was studied by compacting the nano-powder through cold isostatic pressing where maximum densification of 98.4% was achieved at 1550 degrees C. During Vickers indentation using a 5 kg load, cracks were propagating around the grain boundaries and fractured the ZrO2 particles, which was associated with t-ZrO2 to m-ZrO2 transformation. Sintering was studied in the absence of a mineraliser. (c) 2006 Elsevier Ltd. All rights reserved.