Resistance of composite materials based on BaCeO3 against the corrosive effects of carbon dioxide and water vapour at intermediate fuel cell operating temperatures

The objective of this work is to analyse the chemical stability of BaCe0.85Y0.15O3−δ –Ce0.85Y0.15O2−δ (BCY15–YDC15) composite materials at 600 °C and to compare the aforementioned chemical stability with that of pure BCY15. The composite powders were obtained by mixing together powders of BCY15 and YDC15 in the following volume fractions: 90 % BCY15 + 10 % YDC15, 70 % BCY15 + 30 % YDC15, 30 % BCY15 + 70 % YDC15, 20 % BCY15 + 80 % YDC15 and 10 % BCY15 + 90 % YDC15. After that both powders and sintered samples of the BCY15 and the BCY15–YDC15 composites were saturated in two different atmospheres at 600 °C: CO2/H2O (3.1 mol% H2O) and N2/H2O (46.8 mol% H2O). The effects of the previously mentioned atmospheres on the physicochemical properties of the samples were investigated via differential thermal analysis (DTA) combined with thermogravimetric analysis (TG). Furthermore, mass spectrometry was used to analyse the chemical composition of the gases released from the samples during the DTA–TG heating process. The surface and cross-section morphology of the samples were examined by scanning electron microscopy. Moreover, the phase composition of each sample was studied via X-ray Diffraction. From the combined analysis, it can be concluded that the addition of YDC15 in the composite samples leads to an increase in resistance against the corrosive effects of CO2. Furthermore, it was determined that all samples maintain stability in the presence of H2O at 600 °C

A new concept of highly modular ASV for extremely shallow water applications

This paper describe SWAMP, a prototype Autonomous Surface Vehicle (ASV) representing the base for the design and development of an innovative class of reliable modular reconfigurable lightweight ASVs for extremely shallow water applications. The design of SWAMP-class ASVs is based on a holistic approach involving different aspects of robotics such as the use of soft materials, the mechanical design of innovative propulsion system integrated with the vessel hull, the adoption of modular mechanical and computing architecture able to support multi-agent distributed GNC systems

Inkjet Printing Functionalization of SOFC LSCF Cathodes.

An important segment of the future renewable energy economy is the implementation of novel energy generation systems. Such electrochemical systems are solid oxide fuel cells, which have the advantage of direct conversion of the chemical energy stored in the fuel to electrical energy with high efficiency. Improving the performance and lowering the cost of solid oxide fuel cells (SOFCs) are strongly dependent on finding commercially viable methods for nano-functionalization of their electrodes via infiltration. Inkjet printing technology was proven to be a feasible method providing scalability and high-resolution ink delivery. LaxSr1-xCoyFe1-yO3-δ cathodes were modified using inkjet printing for infiltration with two different materials: Gd-doped ceria (CGO) commonly used as ion-conductor and La0.6Sr0.4CoO3-δ (LCO) commonly used as a mixed ionic electronic conductor. As-modified surface structures promoted the extension of the three-phase boundary (TPB) and enhanced the mechanisms of the oxygen reduction reaction. Electrochemical impedance measurements revealed significantly lowered polarization resistances (between 2.7 and 3.7 times) and maximum power output enhancement of 24% for CGO infiltrated electrodes and 40% for LCO infiltrated electrodes

Mixing the spacers in azacryptands: effects on halide recognition

Replacement of just one spacer in dicopper cryptates drastically alters the cavity's shape, thus affecting halide recognition

Towards the fabrication of sintered IDEAL-Cells by tape casting, wet powders spraying and screen printing

The realization of complete anode supported cells reproducing the IDEAL-Cell concept was approached by standard and inexpensive ceramic processes like tape casting, screen printing and wet powder spraying. Both commercial and custom powders were employed to build-up layers for button cells (1 inch footprint) and larger (5?5 cm2) substrates. This paper reports the details of the slurries formulation as well as the deposition parameters and sintering conditions. Resulting microstructural features are also presented together with an outlook on future steps of the activit

Composition and grain size-driven ferroelectric-relaxor crossover in Ba(Zr,Ti)O3 ceramics

First Ba(Zr,Ti)O3 (BZT) ceramics with various compositions prepared by solid state, with high density, homogeneous microstructures and grain sizes in the range (0.7-4) ?m were studied. Besides the dielectric and ferroelectric investigations, First Order Reversal Curves method was employed to describe the changes of the switching properties induced by composition and grain size, related to the ferroelectric-relaxor crossover. The dielectric and ferroelectric data for ceramics with similar grain sizes demonstrated the expected ferroelectricrelaxor crossover induced by increasing x. For a given composition (x = 0.10), the relaxor character increases whit reduction of the grain size. The FORC distribution shows almost zero reversible contribution and well separated sharp irreversible component for larger grains, while more diffuse distribution with a continuous extension from Ec=0 (reversible) to Ec?0 (irreversible, switching) is typical for finer grains.

Dense dielectric ceramics with local graded structure from core-shell particles: preparation and properties

The modification of the surface properties of particles by coating with a different material, resulting in the formation of core-shell structures, is a well-known process. However, the consolidation of core-shell particles in bulk ceramics has not been extensively investigated yet, mainly because of the difficulty in controlling interdiffusion and interface reactions. In this study, we have coated BaTiO(3) spherical templates with SrTiO(3) and BaZrO(3) using a precipitation process from inorganic precursors. The size of the particles as well as the overall composition can be tailored over a wide range. Densification of the resulting core-shell particles was accomplished either using conventional sintering or spark plasma sintering. Dense ceramics with a graded composition at the level of the single grains could only be obtained by careful choice of the sintering conditions. The final ceramics show strongly modified dielectric properties in comparison to both the parent compounds and the homogeneous solid solutions. The proposed approach is quite generic and suggests new possibilities for the realization of polycrystalline materials with local graded structure by the controlled sintering of core-shell particles

Properties of compositionally graded Ba(1-x)SrxTiO(3) thick films

Compositionally graded thick films (0.4 mm) have been fabricated using the airflow deposition method. Films were made of five layers with different composition Ba1-xSrxTiO(3) (BST, x=0, 0.1, 0.2, 0.3 and 0.4). The layers presented different thicknesses, ranging from 80 to 30 microns, but similar Vickers microhardness. The average particle size of deposited layers was below 500 nm and the density of asdeposited films was about 80% of theoretical. After sintering at 1350 ?C samples presented increaseddensity (>90%) and maintained a compositional gradient. When compared to single-composition BST ceramics, permittivity of graded films was much less dependent on temperature over a wide range, from -50 to 250 ?C. In addition, the films displayed polarisation offset when driven by an alternating field and heated above 50?C