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Here, an easy and effective electrochemical route towards the synthesis of gold thin films with well-controlled roughness, morphology and crystallographic orientation is reported. To control these different factors, the applied potential during deposition played a major role. A tentative nucleation and growth mechanism is demonstrated by means of electrochemical characterizations and a formation mechanism is proposed. Interestingly, the differences in geometry and orientation of the different gold deposits have shown a clear correlation with the electrocatalytical activity in the case of oxygen sensing. In addition, not only the electrocatalytical activity but also the surface-enhanced Raman scattering of the gold deposits have been found to depend both on the roughness and on the size of the surface nanostructures, allowing a fine tuning by controlling these two parameters during deposition.

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The paper presents the complete rheological profile of boron nitride (BN)–ethylene glycol (EG) nanofluids. Nanofluids have been produced by two-step method on the basis of commercially available powder of plate-like grains of nanometrical thickness. Viscoelastic structure has been determined in oscillatory measurements at a constant frequency and temperature. Viscosity and flow curves for these materials have been measured. Studies have shown that the Carreau model can be used for the modeling of dynamic viscosity curves of the material. The samples were tested for the presence of thixotropy. The dependence of viscosity on temperature was also examined. The effect of temperature on the dynamic viscosity of BN-EG nanofluids can be modelled with the use of Vogel-Fulcher-Tammann expression.

The main advantage of ceramic-metal composites is the increase of fracture toughness of the brittle ceramic matrix. The slip casting method gives the possibility to obtain products of complicated shapes without green machining.In the work results concerning colloidal and rheological aspects of ceramic-metal composite fabrication via the slip casting method are presented. Slurry consisted of ceramic (α-Al 2 O 3 ) and nickel powder suspended in water with addition of deflocculants composition (citric acid and diammonium citrate), surface-active agents and binder. Ceramic and metallic powders show great differences in electrokinetic behavior, which cause that the heteroflocculation effect in the suspension can take place. In order to investigate the particles interaction characteristics, the zeta potential of each powder was examined. The zeta potential measurements were performed for diluted suspensions as a function of pH. Rheological measurements of the slurries were performed. Although surface of alumina was modified, so that the electrokinetic behavior resembled one of nickel, it turned out that the presence of nickel particles has great influence on the slurry properties. The change of rheological properties for slurries containing nickel particles results probably from strong interaction between alumina and nickel particles.Keywords: alumina, ceramic-metal composite, nickel, slip casting, zeta potential Do korzystnych cech ceramiki można zaliczyć dużą twardość, sztywność, odporność na ścieranie oraz niską gęstość. Jednak kruchość tych materiałów ogranicza obszar ich zastosowania. Jedną z metod zwiększenia odporności na kruche pękanie jest realizowane poprzez wprowadzenie plastycznych cząstek metalu do osnowy ceramicznej.Przedstawiono wyniki badań właściwości mas lejnych do otrzymywania kompozytów o osnowie z tlenku glinu z rozproszonymi cząstkami niklu metodą odlewania z mas lejnych na bazie proszków metalicznego i ceramicznego. W skład mas lejnych wchodziła mieszanina proszku tlenku glinu i niklu oraz układ upłynniaczy, środek powierzchniowoczynny i spoiwo. Materiały wykorzystane w badaniach charakteryzują się dużą różnicą ich właściwości elektrokinetycznych, przez co w ich mieszaninie może dochodzić do efektu heteroflokulacji (przyciągania się elektrostatycznego cząstek o różnego rodzaju i o różnym ładunku).W niniejszej pracy przedstawiono opis zjawisk elektrokinetycznych występujących w układzie tlenek glinu i nikiel na podstawie pomiarów potencjału zeta zarówno w wodzie, jak i w roztworze upłynniaczy stosowanych w masie lejnej. Ponadto przeprowadzono badania właściwości reologicznych w celu określenia wpływu obecności cząstek metalicznych w masie lejnej na właściwości zawiesiny. Wprowadzane do masy lejnej środki upłynniające modyfikują powierzchnię tlenku glinu minimalizując aglomerację cząstek związaną z efektem heteroflokulacji. Pomimo to zaobserwowano znaczny wpływ obecności cząstek niklu na właściwości reologiczne mas lejnych.

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The paper presents the results of measurements of rheological properties of ethylene glycol (EG) based aluminum oxide (Al2O3) nanouids. The nanouids have been produced by two-step method with the use of commercially available nanoparticles. Dynamic viscosity curves and dependence of viscosity on temperature for these materials have been measured. It has shown that with higher concentration of nanoparticles in the suspension, these nanouids exhibit the non-Newtonian ow and it can be considered as shear-thinning liquids. The eect of temperature on the dynamic viscosity in Al2O3EG nanouids can be modelled with the use of VogelFulcher Tammann expression.

In the work the research on properties of an yttria nanopowder obtained by solution combustion synthesis (SCS) in terms of its application in ceramic technology is presented. In order to characterize the SCS reaction the decomposition of yttrium nitrate, glycine and their solution was investigated using differential thermal analysis coupled with FT-IR spectrometry of the gases emitted during the measurements. The product obtained in the SCS process was characterized in terms of its microstructure, particle size distribution and BET specific surface. Although the obtained powders showed nanoscaled structures, only after calcination at a temperature of 1100 °C nanosized particles were revealed. The calcined powder occurred in an agglomerated state (cumulants mean Zave = 1.3 µm). After milling particle size was successfully decreased to Zave = 0.28 µm. The deagglomerated powder was isostatically densified and tested for sintering ability. The obtained nanopowder showed very high sintering activity as the shrinkage onset was detected already at a temperature of about 1150 °C.