Hidrotermička sinteza cirkonijevih nanoprahova i tankih prevlaka

The synthesis of nano-powders was accomplished using different physical, mechanical and chemical methods. Hydrothermal processes have been recently reported as a very attractive route in the synthesis of both zirconia powders and films. The present paper presents some aspects of the microstructural evolution of zirconia nanomaterials obtained via hydrothermal process starting from soluble peroxide precursors.Sinteza nanoprahova izvršena je uporabom raznih fizičkih, mehaničkih i kemijskih metoda. Od nedavno se o hidrotermičkom procesu govori kao o vrlo atra-ktivnom načinu sinteze cirkonijevog praha i tanke prevlake. Ovaj rad predstavlja neke aspekte mikrostrukturalne evolucije cirkonijevih materijala dobivene hidrotermičkim procesom koji počinje s topljivim početnim peroksidnim materijalom

Iron oxide/PAMAM nanostructured hybrids: combined computational and experimental studies

Recent studies in the field of iron oxide–dendrimer hybrids showed an increased potential of these materials to be used in diagnosis, monitoring, targeting, and therapy of cancer. The aim of this paper is to investigate the nature of interactions between iron oxide nanoparticles and polyamidoamine (PAMAM) dendrimers using computational and experimental techniques, namely molecular dynamics (MD) and electron paramagnetic resonance (EPR). Hybrid nanostructures based on iron oxide and PAMAM dendrimers were prepared in one-step synthesis route, using hydrothermal method at high pressure (40–100 atm). The interaction between dendrimers and iron oxide nanoparticles was predicted at specific temperature, pH, and pressure conditions. The same conditions were applied for hydrothermal synthesis. High-resolution transmission electron microscopy revealed the formation of magnetite (MAG) through hydrothermal reaction at 100 atm, starting only from iron (III) chloride. A possible explanation could be the variation of the fugacity value of oxygen under high-pressure conditions, which leads to diffusion-controlled reaction and to transformation of haematite into MAG. EPR parameter, namely linewidth, was exploited to evaluate the type of interactions from iron oxide–PAMAM hybrids, due to its dependence on spin–spin relaxation time and spin–lattice interactions. As a conclusion, MD indicated the existence of electrostatic interactions between PAMAM and iron oxide. In accordance with in silico results, EPR analysis suggested that MAG is not entrapped in PAMAM structure and the interactions between organic and inorganic components take place at dendrimer’s surface. A good agreement between MD simulations and experimental results was observed

Microstructural aspects of the protective ceramic coatings applied on the surfaces of refractory alloys produced by additive manufacturing

The possibility of depositing multi layers made of metals/alloys and high temperature ceramics by electron beam physical evaporation process under high vacuum (EB-PVD) on the surface of a parallelepiped sample made by selective laser melting (SLM) from a Ni base refractory super alloy was experimentally tested. The SEM-EDAX micro structural analysis revealed the morphology and thickness of the coatings consisting of a NiCrAlY base alloy as bonding layer and three successive YSZ, LZO and GZO ceramic layers on the Ni-based super alloy substrate obtained by additive manufacturing. The adhesion of the layer deposited was evaluated by the scratch test method. The analysis highlighted the importance of pre-preparing the surface of the additive manufactured substrates, in order to control the adhesion and uniformity of the deposited layers