Melis Arin

Fully dense ZrO2-TiN composites containing 1.75-2 mol %Y2O3, 1 mol% Y2O3 and 1 mol% Nd2O3 stabilizers, small amounts of Al2O3, and electrical conductive TiN particles (40-70 vol%) have been produced by hot pressing and spark plasma sintering at 1550°C. Although the intrinsic hardness of TiN (1400 kg/mm²) is higher than that of t-ZrO2 (1200 kg/mm²), the decreasing hardness trend can be attributed to the larger TiN grain size with the higher TiN content. Since TiN is more brittle, the fracture toughness decreases with increasing TiN content. Transformation toughening has been attributed as the main toughening mechanism as a result of fracture toughness decreasing with the transformability. Spark Plasma sintering temperature was too high for mechanical properties and hydrothermal stability of the mixed stabilized composites. The transformability decreases so hydrothermal stability increases linearly with increasing TiN content as a result of smaller volume fraction of t-ZrO2 grains bec...

Self cleaning surfaces and coatings are more and more frequently finding their way towards everyday applications. This poster reviews our progress made on an aqueous CSD method used for the deposition of photocatalytically active TiO2 thin films. Dip-coating out of a solution was applied to deposit thin films on glass substrates. Starting from titanium(IV)butoxide we achieved a stable titanium precursor solution by forming titanium-peroxo compounds by reaction between titanium(IV)butoxide and hydrogenperoxide. According to several observations during the synthesis procedure a possible reaction mechanism was proposed. Confirmation of these possible occurring reactions was acquired via thermal analysis, UV-Vis and infrared spectroscopy. A more thorough knowledge of the chemistry behind this synthesis process allowed us to achieve a better control over several solution parameters, such as stability and viscosity. We realized the deposition of anatase TiO2 films with good transparency i...

Self cleaning surfaces and coatings are more and more frequently finding their way towards everyday applications. This poster reviews our progress made on an aqueous CSD method used for the deposition of photocatalytically active TiO2 thin films. Dip-coating out of a solution was applied to deposit thin films on glass substrates. Starting from titanium(IV)butoxide we achieved a stable titanium precursor solution by forming titanium-peroxo compounds by reaction between titanium(IV)butoxide and hydrogenperoxide. According to several observations during the synthesis procedure a possible reaction mechanism was proposed. We realized the deposition of anatase TiO2 films with good transparency in the visual light region and excellent abrasion resistance. Decomposition of organic polluents was confirmed by the breakdown of ethanol. This low-carbon containing synthesis method offers promising opportunities towards the manufacturing of transparent, photocatalytic coatings and allows for furt...

In this paper, we present an inkjet printing approach suited for the deposition of photocatalytically active, transparent titanium oxide coatings from an aqueous, colloidal suspension. We used a bottom-up approach in which a microwave-assisted hydrothermal treatment of titanium propoxide aqueous solutions in the presence of ethylenediaminetetraacetic acid and triethanolamine was used to create suspensions containing titania nanoparticles. Different inkjet printing set-ups, electromagnetic and piezoelectric driven, were tested to deposit the inks on glass substrates. The presence of preformed titania nanoparticles was expected to make it possible to reduce the heating temperature necessary to obtain the functionality of photocatalysis which can widen the application range of the approach to heat-sensitive substrates. We investigated the crystallinity and size of the obtained nanoparticles by electron microscopy and dynamic light scattering. The rheological properties of the suspensions were evaluated against the relevant criteria for inkjet printing and the jettability was analyzed. The photocatalytic activity of the obtained layers was analyzed by following the decomposition of a methylene blue solution under UV illumination. The influence of the heat treatment temperature on the film roughness, thickness and photocatalytic activity was studied. Good photocatalytic performance was achieved for heat treatments at temperatures as low as 150 °C, introducing the possibility of using this approach for heat-sensitive substrates.

In this work, aqueous chemical solution deposition precursors suited for inkjet printing, are used for the synthesis of photocatalytically active TiO2 coatings and BaTiO3 thin films. Environmentally friendly precursor solutions with electromagnetic ink-jet printing, allows cheap and simple processing of TiO2 films on glass and BaTiO3 films on LSMO substrates. The hydrolysis reaction of water sensitive titanium alkoxide (Ti-alkoxide) precursor is controlled by adding complexing agents such as citric acid and triethanolamine, and aqueous stable solutions are achieved. The pH of the solutions is brought to neutral to guarantee flexible processing and avoid damage to substrates and equipment. Ba ions are stabilized by using citric acid, ethyleneglycol, and nitrilotriacetic acid, and BaTiO3 solutions are prepared by mixing separate Baand Tiprecursor solutions at the same pH levels. Solution parameters are adapted to obtain optimal gelation conditions and good jettability. The influence o...

ABSTRACT A water-based BaTiO3 precursor solution, suited for ink-jet printing of hetero-epitaxial BaTiO3 layers on LaAlO3 single-crystal substrates was developed. First, a study on the simultaneous stabilization of Ba2+ and Ti4+ions in a neutral, aqueous environment was performed. Thermal analysis of the precursor was used to select appropriate temperature programs and the rheology of the solutions is studied to optimize dipcoating and later ink-jet printing parameters. On both substrates, it was possible to obtain epitaxial layers of about 200 nm thickness after sintering at temperatures above 1000 °C. Currently, we are adapting the thermal program and heating atmosphere in order to reduce the sintering temperatures, decrease the surface roughness and increase density.

ABSTRACT In order to study bicompability properties of fully dense ZrO2 ceramics containing 2-3 mol% Y2O3 stabilizer, and ZrO2-TiN composites containing 1-1.75 mol Y2O3 and 1 mol% Nd2O3 stabilizers, and electrical conductive TiN particles (40-60 vol%), cell viability was evaluated based on the reduction of tetrazolium salt to formazan crystals by living cells, the alkaline phosphatase production was investigated, and nitrite quantification was done for indirect evaluation of osteoblast NO production. The samples were defined biocompatible since there is not any significant change observed in the physiological functions of the cells when incubated together.