Pressureless sintering of injection molded zirconia toughened alumina nanocomposites

Abstract

Ceramic injection molding (CIM) is the most suitable shaping method for mass production of small ceramic components with complex shape in near net shape quality. Due to its high strength and fracture toughness zireonia toughened alumina (ZTA) is an interesting material for ceramic machine components and for biomedical applications. The ability to sinter ZTA to full density while retaining an extremely fine grained microstructure is the prerequisite to exploit the potential of the material. CIM components of ZTA which have much lower powder packing density and a lower homogeneity than e.g. isopressed or cast components normally show a very sluggish sintering behaviour even if very fine sub-μm or even nanosized powders are used. In this study a tailored pressureless sintering process for ZTA microcomponents was developed in order to be able to exploit the full technical and economic potential of the near-net-shape manufacturing process. Depending on the feedstock recipe a reduction in sintering temperature by more than 100 K was achieved and even higher densities reached than by conventional sintering. This leads to a refinement in microstructure and a reduction in alumina grain size by a factor of 2-3.