Fiber sintered metal fibers

Sintered metal fibers with filaments of uniform size (2-40 (tm), made of SS, Inconel, or Fecralloy , are fabricated in the form of panels. Gauzes based on thicker wires (100-250 tm) are made from SS, nickel, or copper. They have a low surface area of about 10 m g. Several procedures are used to increase the surface area, for example, leaching procedures, analogous to the production of Ra-Nickel, and electrophoretic deposition of particles or colloid suspensions. The porosity of structures formed from metal fibers range from 70 to 90%. The heat transfer coefficients are high, up to 2 times larger than for random packed beds [67]. 

ITottinen et al. [44,45] used htanium sintered meshes as DEs on the cathode side of a PEMEC because the porosity of these metal sheets does not reduce when in compression. It was demonstrated that in order ter the cell to achieve the required performance, the sintered meshes had to be coated with platinum. However, the results showed that a cell with CEP (SIGRACET GDEIO-BB) as the DE shll performed slightly better (especially at high current densities) than the cell with the Pt-coated sintered Ti mesh. Cisar et al. [46 presented another example in which a DE consisting of sintered metal fibers was used on the cathode side of a PEMEC. Once put together, these fibers were rmified or bonded to the EE plate (made out of metal) in order to combine the two components into one. 

As an alternative to foams, fibrous materials in the form of tissues or filters may be used as structured catalysts [53,62-65]. Of particular interest for MSRs are sintered metal fibers (SMFs) [64,65]. These materials have open and homogeneous structures with porosities of 70-90% and high thermal conductivities, which ensure homogeneous temperatures in the catalytic bed. SMF materials consist of thin metallic fibers of 10-20 pm diameter. The small fiber diameters ensure high external fluid-solid mass transfer [66]. The fibers can be covered with a homogeneous layer of zeolitic material [66] or a washcoat, which can be impregnated with an active material [67,68]. Luther et al. [67] integrated the SMF catalyst in a... 

FIGURE 7 Schematic illustration of a sandwich reactor (top) and scanning electron microscopic images of a sintered metal fiber catalyst. 

I. Yuranov, A. Renken, L. Kiwi-Minsker, Zeolite/sintered metal fibers composites as effective multi-structured catalysts, Appl. Catal. 281 (2005) 55. 

Typically, air is filtered through spun glass-fiber before and after mixing with ammonia, whereas ammonia liquid is passed through magnetic separators to remove iron and iron oxide particles and ammonia vapor through sintered metal fiber. 

Figure 11.18 Three-level structure of a zeo-lite/sintered metal fiber catalytic bed (a) microstructure of a zeolite film of oriented submicron crystals, (b) mesostructure of...

Figure 11.19 Staged bubble column reactor with integrated structured catalyst layers and microheat exchanger (a) vertical cut through the heat exchanger element (b) and sintered metal fiber catalyst (c) [53]. (Adapted with permission from Elsevier.)...

Figure 11.20 Schematic representation of structured sintered metal fiber support applied for IL-phase catalysis during gas-phase hydrogenation. (Adapted from [62]. Reproduced with permission from Elsevier.)...

Figure 6.6 (a) Schematic presentation of a "sandwich" reactor and (b) SEM images of sintered metal fiber (SMF) catalyst. (Reproduced from Ref. [22]. Copyright 2008, John Wiley Sons.)... 

Filtration is accomplished with wire mesh screens (square or twill weave), sintered powder, or sintered metal fibers. Table 12.5 shows a comparison of the various filtration media and their characteristics. Square weave screen. Fig. 12.50, has every other wire... 

Sintered metal fiber filters are virtually identical in design and operation to etched disk filters. See Figure 3-25 and the previous discussion. Sintered metal fiber filter elements consist of layers of metal fibers which have been mechanically compressed and then sintered together. Typical. sintered metal fiber element life in amine service is 18 months (Clark,... 

The shorter life of sintered fiber elements in comparison to the etched disk element is compensated for by a significantly lower cost per element. Sintered metal fiber elements in amine service are typically rated at 10 microns absolute (Clark, 1996). Since these systems are completely automated, operator acceptance problems are avoided. A sintered metal fiber element housing for amine filtration service is depicted in Figure 3-26b. PTl Technologies of Newbury Park, CA, manufactures sintered metal fiber filters for amine service, while Pall Well Technologies. Inc. of East Hills. NY. makes similar automatic sintered metal powder and sintered metal fiber filters for amine service. Pall also markets an automatic backflush amine filter which uses non-mctallic filter elements (Calhcart. 1996). 

Other fibrous and porous materials used for sound-absorbing treatments include wood, cellulose, and metal fibers foamed gypsum or Pordand cement combined with other materials and sintered metals. Wood fibers can be combined with binders and dame-retardent chemicals. Metal fibers and sintered metals can be manufactured with finely controlled physical properties. They usually are made for appHcations involving severe chemical or physical environments, although some sintered metal materials have found their way into architectural appHcations. Prior to concerns regarding its carcinogenic properties, asbestos fiber had been used extensively in spray-on acoustical treatments. 

Ceramic matrix composites are produced by one of several methods. Short fibers and whiskers can be mixed with a ceramic powder before the body is sintered. Long fibers and yams can be impregiated with a slurry of ceramic particles and, after drying, be sintered. Metals (e.g., aluminum, magnesium, and titanium) are frequently used as matrixes for ceramic composites as well. Ceramic metal-matrix composites are fabricated by infiltrating arrays of fibers with molten metal so that a chemical reaction between the fiber and the metal can take place in a thin layer surrounding the fiber. 

Catalyst bodies can also be made of knitted threads or woven in fabrics, felts, etc. (5-7) (Figure 5). A wide variety of materials have been considered for such catalysfs, buf mosf affenfion has been given to glass, sintered metal, and carbon fibers. 

A still higher membrane packing density can be accomplished with some geometries available to certain commercial organic membranes. One such attempt is hollow fibers [Baker et al., 1978 Beaver, 1986]. Sintered monolithic hollow fibers of metals or metal oxides have been developed [Dobo and Graham, 1979] but their burst strengths appear to be critical. Further developments are needed before commercialization. 

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