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Result: Micro-sized powders by hydrochemical synthesis
Expected Impact/Targeted User Groups: High-quality powders for a series of additive and sintering process applications and increasing market share / Powder use industry in general
A versatile hydrochemical process combined with spray drying has been developed to synthesize different types of ceramic nanopowders with controlled chemical, structural and morphological composition. These methods proved particularly promising in terms of controlling the grain size, degree of agglomeration and purity of powders that can be sintered without significantly changing the phase composition by micro-FAST process. The process has been demonstrated for producing ceria-doped zirconia-based powders (Ce-YSZ) for SWATCH watch parts and doped lead zirconate titanate (Nd,La-PZT) piezoceramics. The process is based on a hydrothermal process in autoclaves at temperatures below 2500C and pressures below 100 atm. starting from pure soluble metallic salts in the presence of a hydrolysis agent to control the pH process. The filtered and washed precipitate obtained is re-dispersed in the presence of a small amount of organic binder and granulated by spray-drying at temperatures below 2000C through a calibrated nozzle. No further thermal treatment is required for crystallization, thus allowing one step synthesis of nanocrystalline powders with controlled degree of agglomeration.The process is designed to minimize the wastes by a simple recycling loop of the by-products, while the agglomeration process eliminates the nano-toxicity risks during handling. The characteristics of the powders obtained are assessed by certified methods: ICP-OES chemical analysis (main elements, doping elements, purity); XRD (crystallinity); ASTM B 213-03 (flowability); ASTM B923-02, D7481-09 and B527 (density), particle sizes (sieve analysis). All powders were delivered with safety data sheets.