Preparation of nano-composites by advanced colloidal processing

Summary form only given. The aim of the present work was to identify a systematic and investigation on the influence of processing conditions (dispersant stabilizing mechanism and solid loading, particle size and particle size distribution, temperature and sintering aid addition-yttria) on colloidal processing of alumina toughened zirconia (ATZ) nano composites was conducted. Rheology was the main tool used to evaluate and control the correct processing of the powders. The investigation was rather comprehensive, accounting for all processing steps from suspension preparation, consolidation, drying and sintering. The ultimate goal was to establish a correct methodology to process of alumina and tetragonal stabilized zirconia-doped-3 mol.% yttria and mixture of ATZ powders with advanced colloidal techniques for the preparation and optimization of high stable slurries with high solids content up to 77 wt.% for production of nano composites objects with improved properties and to establish as clearly as possible relationships between processing and microstructures, i.e. how processing controls or modifies the microstructure. Different type of polyelectrolyte dispersants have been used which just an organic deflocculating agent (DOLAPIX CE 64, Zschimmer & Schwarz, Germany) that is free from alkali, completely dissociated in suspension immediately and with better effect by high stability, homogeneous incorporation with lower viscosity into the slip. Stability of suspensions prepared by planetary ball-mill (Pulverisette 6, Fritsch, Germany). Rheological properties of suspensions was characterized by rotational viscometry (Haake viscometer, RV1, Germany) for shear rates between 0 and 1000 s/sup -1/. An elector-acoustic technique called: "electrokinetic sonic amplitude (ESA)" applied for characterization of the dispersing behavior of high solid concentrated (77 wt.%) suspensions in double distilled water with or without the adding of an anionic polyelectrolyte as disperant. The results of this work present the necessary basis for the development of new type of nano-materials applied for nano-technological applications which from especially such as apply for the compositional gradient composites that combine e.g. the advantages of the high wear resistance of alumina and the high fracture toughness of zirconia.