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King Abdulaziz City for Science, Technology and Fraunhofer Institute for Silicate Research | Date: 2015-12-01

The invention provides a dust repellant and anti-reflective inorganic coating and the method for preparing the coating. The dust repellant and anti-reflective inorganic coating includes nano-porous silica (SiO_(2)) network of about 5 nm to about 35 nm and is characterized by cracks. The method of preparing the dust repellant and anti-reflective inorganic coating on a substrate includes mixing of aqueous SiO_(2 )solution with a solvent. The aqueous SiO_(2 )solution with the solvent is stirred to form a solution. The solution is coated on the substrate to form a film on the surface of the substrate. Thereafter, the film is annealed by heating the film to a temperature of about 500 C. to about 700 C. within a period of about 2 minutes to about 2 hours. Finally, the film is allowed to cool down.

Sanchez C.,CNRS Laboratory of Condensed Matter Chemistry, Paris | Belleville P.,CEA Le Ripault | Popall M.,Fraunhofer Institute for Silicate Research | Nicole L.,CNRS Laboratory of Condensed Matter Chemistry, Paris
Chemical Society Reviews | Year: 2011

Today cross-cutting approaches, where molecular engineering and clever processing are synergistically coupled, allow the chemist to tailor complex hybrid systems of various shapes with perfect mastery at different size scales, composition, functionality, and morphology. Hybrid materials with organic-inorganic or bio-inorganic character represent not only a new field of basic research but also, via their remarkable new properties and multifunctional nature, hybrids offer prospects for many new applications in extremely diverse fields. The description and discussion of the major applications of hybrid inorganic-organic (or biologic) materials are the major topic of this critical review. Indeed, today the very large set of accessible hybrid materials span a wide spectrum of properties which yield the emergence of innovative industrial applications in various domains such as optics, micro-electronics, transportation, health, energy, housing, and the environment among others (526 references). © 2011 The Royal Society of Chemistry.

Von Hagen R.,University of Cologne | Lorrmann H.,Fraunhofer Institute for Silicate Research | Moller K.-C.,Fraunhofer Institute for Silicate Research | Mathur S.,University of Cologne
Advanced Energy Materials | Year: 2012

LiFe 1-y Mn y PO 4 /C nanofiber composites are applied as cathode materials in Li-ion batteries and their electrochemical properties are explored. Nanofiber meshes are synthesized via electrospinning of commercially available precursors (LiOH·H 2O, FeSO 4·7H 2O,MnSO 4·H 2O,H 3PO 4, and polyvinylpyrrolidone). Nanofibers calcined at 850 °C under Ar/H 2 (95/5 vol%) atmosphere are directly used as self-supporting electrodes in Swagelok half cells without the need for any conductive additive or polymer binder. The morphology, phase, and chemical composition of as-prepared and heat-treated samples are analyzed by means of X-ray powder diffraction, thermogravimetric analysis, and electron and scanning microscopy techniques. Brunauer-Emmett-Teller gas adsorption-desorption measurements show a high specific surface area (111m 2 g -1 ) for LiFe 0.5 Mn 0.5 PO 4. The influence of different Fe/Mn ratios on the morphology, electrical, and electrochemical performances are analyzed. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Schwarz G.,University of Würzburg | Hasslauer I.,University of Würzburg | Kurth D.G.,University of Würzburg | Kurth D.G.,Fraunhofer Institute for Silicate Research
Advances in Colloid and Interface Science | Year: 2014

Introducing metal ion coordination as bonding motive into polymer architectures provides new structures and properties for polymeric materials. The metal ions can be part of the backbone or of the side-chains. In the case of linear metallo-polymers the repeat unit bears at least two metal ion receptors in order to facilitate metal-ion induced self-assembly. If the binding constants are sufficiently high, macromolecular assemblies will form in a solution. Likewise, polymeric networks can be formed by metal ion induced crosslinking. The metal ion coordination sites introduce dynamic features, e.g. for self-healing or responsive materials, as well as additional functional properties including spin-crossover, electro-chromism, and reactivity. Terpyridines have attracted attention as receptors in metallo-polymers due to their favorable properties. It is well suited to assemble linear rigid-rod like metallo-polymers in case of rigid ditopic ligands. Terpyridine binds a large number of metal ions and are readily functionalized giving rise to a plethora of available ligands as components in metallo-polymers. By the judicious choice of the metal ions, the design of the ligands, the counter ions and the boundary conditions of self-assembly, the final structure and properties of the resulting metallo-polymers can be tailored at all length scales. Here, we review recent activities in the area of metallo-polymers based on terpyridines as central metal ion receptors. © 2013 Elsevier B.V.

Lorrmann H.,Fraunhofer Institute for Silicate Research
Large Lithium Ion Battery Technology and Application Symposium, LLIBTA 2015 and Large EC Capacitor Technology and Application Symposium, ECCAP 2015 - Held at AABC Europe 2015 | Year: 2015

• Solid-state batteries with improved volumetric energy density • Sol-gel process for anode, cathode, electrolyte developed • Continuous, large scale coating process • Coating on coating of components • Interface is crucial, interface resistance can be reduced by wet chemical coating.

Andreas N.,Fraunhofer Institute for Silicate Research
Journal of the European Ceramic Society | Year: 2014

We demonstrate the possibility to fabricate SiC monofilaments with large diameters of 100. μm by a polymer route using a dry-spinning process. The properties of the spinning solution and the parameters of the spinning process were optimized to achieve a circular cross section of the spun filaments despite their large diameter. The evolution of the diameter and the mechanical properties of the filaments with pyrolysis temperature were studied. Filament shrinkage started above 400. °C. A radial shrinkage of about 25% was measured for pyrolysis temperatures of 1200. °C. The mechanical properties significantly start to increase at pyrolysis temperatures above 600. °C. At a diameter of 100. μm the filaments show a tensile strength of 620. MPa and a tensile modulus of 138. GPa after pyrolysis at 1200. °C. A decrease in the filament diameter leads to an improvement of the mechanical properties. We demonstrate the fabrication of these SiC monofilaments on spools. © 2014 Elsevier Ltd.

Muller T.M.,Fraunhofer Institute for Silicate Research | Raether F.,Fraunhofer Institute for Silicate Research
Computational Materials Science | Year: 2014

This work presents a computational approach for the accurate three-dimensional modelling of ceramic microstructures and the finite element simulation of their macroscopic properties. Especially, the effect of the grain boundaries was included in the model, as well as the capability to represent multiple phase materials. The model was adapted to corresponding real microstructures with the help of quantitative image analysis of 2D cross sections. Initially, flexible voxel based representative volume elements were used. To be suitable for finite element simulations, an adapted surface tesselation was created from the voxel model, where all the relevant structural parameters were kept constant while the model size was decimated to about 10% of the initial size. In this representation, grain boundaries were introduced by computing a thin offset mesh for each interface. The grain boundary turned out to be essential when impedance spectra were to be simulated, as the electrical conductivity and the dielectric properties both contribute to the complex response to the harmonic electric excitation. Following this approach, the macroscopic properties of porous zirconia-alumina ceramics could be simulated with an accuracy of >90%, as investigated at several ratios of mixture, ranging from pure alumina to pure zirconia. © 2013 Elsevier B.V. All rights reserved.

Bose H.,Fraunhofer Institute for Silicate Research | Rabindranath R.,Fraunhofer Institute for Silicate Research | Ehrlich J.,Fraunhofer Institute for Silicate Research
Journal of Intelligent Material Systems and Structures | Year: 2012

The actuation behavior of soft silicone-based magnetorheological elastomers in magnetic fields of variable strength was investigated. An inhomogeneous magnetic field gives rise to a reversible actuation effect, which is the result of the competition between magnetic and elastic forces in the material. Magnetorheological elastomers are capable of performing more pronounced deformations than known rigid actuator materials. In this article, the actuation behavior of magnetorheological elastomer ring-shaped bodies in a valve-type device for the control of an air flow is demonstrated. For this purpose, magnetorheological elastomer rings with different Shore hardness were prepared and used in the valve. In addition to the common isotropic magnetorheological elastomer samples, rings with an anisotropic arrangement of the magnetic particles were also prepared. The actuation of these anisotropic magnetorheological elastomers was compared with that of the isotropic samples. Based on simulations, the inhomogeneity of the magnetic field at the magnetorheological elastomer material which is required for the actuation could be strongly affected by the shape in the design of the magnetic yoke. In this study, the closing characteristics of the valve with different yoke shapes and magnetorheological elastomer materials were evaluated by measuring the dependence of the air flow rate on the magnetic field strength. It is demonstrated that the air flow through the valve can be controlled by the current in the field-generating coil, which yields the base for a new type of magnetic valve. © The Author(s) 2011.

Bose H.,Fraunhofer Institute for Silicate Research | Ehrlich J.,Fraunhofer Institute for Silicate Research
Journal of Intelligent Material Systems and Structures | Year: 2012

Novel concepts for the magnetic circuit in magnetorheological dampers have been proven. In contrast to the established magnetic circuits where the magnetic field for the control of the magnetorheological fluid is generated by the coil of an electromagnet, hybrid magnetic circuits consisting of at least one permanent or hard magnet and an electromagnet are used in the new approaches. Three different technical configurations are distinguished: (1) The electromagnet is combined with two permanent magnets, whose magnetization cannot be modified even by strong magnetic fields of the electromagnet. The main advantage is the improved fail-safe behavior of the damper in case of a power failure. (2) The electromagnet is combined with a hard magnet, whose magnetization can be modified by the electromagnet. This configuration leads to high energy efficiency, because electric power is only required in short pulses for the switching of the hard magnet. (3) All three types of magnetic field sources, permanent, hard, and electromagnet, are combined in the magnetic circuit, which gives the highest flexibility of the magnetic field generation and the damping control at the expense of a relatively large effort. Demonstrators for magnetorheological dampers with all three magnetic circuits were constructed and their performances were tested. The results of the investigations are described in this paper. © The Author(s) 2011.

Mandel K.,Fraunhofer Institute for Silicate Research | Mandel K.,University of Würzburg | Hutter F.,Fraunhofer Institute for Silicate Research
Nano Today | Year: 2012

Magnetic nanoparticles for adsorption and subsequent magnetic removal of hazardous substances from water, as published in Science in 2006, bears enormous potential for water purification for which there is a growing need all over the world. Many publications followed this idea, but doubts remain whether nanoparticles are really separable and whether the process is really that simple. A closer look reveals uncertainties and the need for more research. © 2012 Elsevier Ltd.

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