Layered microstructures micro structures

A Pt catalyst was applied by dry and wet techniques. By means of sputtering using a mask process protecting parts of the microstructure, the micro channel bottom was coated selectively. In addition, an y-alumina layer was applied by the sol-gel technique. Initially, the whole micro structure was covered by such a layer. Then, photoresist was applied and patterned so that only the channel part remained covered. After removal of the exposed photoresist and unprotected y-alumina, only the channel bottom was coated with y-alumina. 

Ni-YSZ cermets deposited by RF sputtering (230 nm) were found to have micro-structural features consisting of columnar grains 13 to 75 nm long and 9 to 22 nm wide, and showed good adhesion to the YSZ layer on which they were deposited [128], In a three-layer Ni-YSZ-Ni film deposited on NiO by RF sputtering in another study, the YSZ layer exhibited a columnar structure with some pinholes [129], Microstructural and electrochemical features of Pt electrodes patterned by lithography on YSZ have also been studied [130,131]. 

An efficient oxidation catalyst OMS-1 (octahedral molecular sieve) has been prepared by microwave irradiation of a family of layered and tunnel-structured manganese oxide materials. These materials are known to interact strongly with micro-wave radiation, and thus pronounced effects on the microstructure were expected. Their catalytic activity was tested in the oxidative dehydrogenation of ethylbenzene to styrene [27]. 

The features of polycrystalline Sr- and Ba-based ferrites, which have the structure of magnetoplumbite, depend not only on their micro-structure, but also on the state of grain boundaries [1,2]. Generally, nano-sized surface layer (1-3 nm) of the grains differs from the corresponding bulk phase both in microstructure and chemical composition. Besides, the hexagonal lattice of SrFe Oig may contain nano-sized areas of cubic and orthorhombic Sr-enriched phases (SrFeO3 x). 

Abstract The polymer electrolyte fuel cell (PEFC) consists of disparate porous media microstructures, e.g. catalyst layer, microporous layer, gas diffusion layer, as the key components for achieving the desired performance attributes. The microstmcture-transport interactions are of paramount importance to the performance and durability of the PEFC. In this chapter, a systematic description of the stochastic micro structure reconstmction techniques along with the numerical methods to estimate effective transport properties and to study the influence of the porous structures on the underlying transport behavior is presented. 

It is well known that the Bruggeman EMA formula is derived by considering one of the constituents as a small sphere. A deviation from such an assumption required a modification the formula to include depolarization factor. Typically, a value of 0.333 is used as a default value in the EMA layer, which assumes a spherical shape of the inclusion. The other two extremes are 0, for a needle-like or columnar micro structure, and 1 for flat disks or a laminar microstructure. This type of transition was found for polyaniline/poly(methylmethacrylate) blend films presenting with a spherical-like microstructure at low sample concentration, whereas at relatively high concentrations the depolarization factor shifted to values closer to 1. This indicated the formation of flat microstructures due to aggregation of the polyaniline particles [8]. 

The L-shaped structures can simply be made by conventional silicon micro machining. The microstructured wafer was covered by a glass slip using a thin layer of a silicone adhesive [153]. 

The sol-gel method is also used to make very fine spherical particles of oxides. By structuring the solvent with surface-active solutes, other forms can also be realized during condensation of the monomeric reactant molecules to form a solid particle. Figure 8.16 shows that normal or inverse micelles or liquid crystals (liquids having long-distance order) can be formed in such solutes. Micelles are small domains in a liquid that are bounded by a layer of surface-active molecules. In these domains the solid is condensed and the microstructure of the precipitated solid is affected by the micelle boundaries. Monodisperse colloidal metal particles (as model catalyst) have been made in solvents that have been structured with surfactants. In the concentration domains where liquid crystals obtain highly porous crystalline oxides can be condensed. After calcination such solids can attain specific surface areas up to 1000 m /g. Micro-organisms use structured solutions when they precipitate calcite, hematite and silica particles. 

The use of kinetics to optimize the design of an MSR is an important perspective although rarely applied and/or described so far. In this context, several features deserve to be considered as modern microstructured devices approach an efficiency such that the catalyst in the reactor itself becomes performance limiting. Therefore, the specific catalyst activity should be maximized and, assuming already optimized formulations, one way to proceed is to target relatively thick and porous layers, which obviously requires an optimization process, as described below. Here, the current discussion on better using micro- or miHi-structured devices fully applies. 

Micro stereo lithography is a rapid prototyping method to generate 3D molds. It is a maskless process with layer-by-layer fabrication of microstructures via the projection of sliced images of 3D objects, as shown in Fig. 9. A laser beam directs to the photocurable resin which can be classified as an epoxy, vinylether, or acrylate. The 3D structure or mold is built on a platform which can be controlled by an XYZ positioner. When one layer is complete, the plat-... 

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