Pasenko O. Production of nanosize stabilized zirconium dioxide powders by precipitation method

The thesis deals with the issues of scientific foundation of technology for production of nanosize stabilized zirconium dioxide powders by precipitation process. The paper covers physical and chemical processes of yttrium and scandium cations and zirconium hydroxide co-precipitation, their thermal dehydration and obtaining of nanosize stabilized zirconium dioxide powders. The main regularities of yttrium and scandium cations and zirconium hydroxide co-precipitation were established on the basis of thermodynamic and experimental researches of Zr(IV)-OH?, Zr(IV)-Y(III)-OH?, Zr(IV)-Sc(III)-OH? systems. A reliable mechanism of Y(III) and Sc(III) cations and zirconium hydroxide co-precipitation was suggested. The processes of dehydration of coprecipitated zirconium hydroxide and stabilizing elements, amorphous zirconium hydroxide crystallization as well as formation of stabilized zirconium dioxide powdered crystals macrostructure were examined. Researches of original reagents, medium pH, precipitation temperature, dehydration conditions effects upon structure formation processes and disperse characteristics of stabilized zirconium dioxide powders are presented. A comparative analysis of the properties of nanosize stabilized zirconium dioxide powders, produced by the developed methods and “DKKK” (Japan) powders of similar composition, was carried out. It has been shown that powders produced by the developed methods are finer ones. A process flow sheet was developed and optimal process-dependant parameters for production of nanosize stabilized zirconium dioxide powders by precipitation method were established.