Ceramic nanomaterials from aqueous and 1,2-ethanediol supersaturated solutions at high temperature

The aim of this study was the synthesis and physicochemical characterization of some nanosized hydroxides/oxides interesting in the field of ceramic materials with the aim of developing new materials for technological applications in the field of high-performance coatings. In particular, attention was focused on ZrO2⋅nH2O, ZrO2, Zn(OH)2, ZnO, Al2O3⋅nH2O, and Al2O3. The synthesis was carried out in 1,2-ethanediol at 150-160 °C or in water at 90 °C at a high degree of supersaturation in order to achieved nucleation rate much greater than the growth rate. The obtained ZrO2⋅nH2O, Zn(OH)2, and Al2O3⋅nH2O particles were peptized to eliminate possible agglomeration and then calcinated at a suitable temperature to allow the formation of the corresponding anhydrous oxides. The synthesized particles were characterized by scanning and transmission electron microscopy, X-ray diffractometry, and differential thermal analysis coupled with thermogravimetry and Fourier transform infrared spectroscopy. The study showed that all the products can be obtained in the nanostructured crystalline form; ZrO2 presented the interesting feature of different tetragonal/monoclinic ratios depending on the solvent used for the synthesis. Preliminary results on the potentialities of these ZrO2 particles as agents for ultrahard coatings on ceramic surfaces were encouraging and very promising.