Metal filaments, fibres

Bekasrt metal fibres are thin metal filaments produced In various alloys. (Standard alloy ls31GL)... 

In an earlier study, Ducheyne and Hench fabricated composite materials with a bioactive glass (Bioglass ) matrix and stainless steel fibre reinforcement by an immersion technique [25]. Donald et al. have reported on the fabrication of glass and glass-ceramic matrix composites reinforced by stainless steel and Ni-based alloy filaments with diameters in the range 4 to 22 [jum [100, 101]. Glass-encapsulated metal filaments prepared by the Taylor-wire process were used for the fabrication of the composites [100]. 

In contrast to the Pt catalysts discussed above, Ni based catalysts (i.e., also when supported on ZrO usually form coke at such a rapid rate that most fixed bed reactors are completely blocked after a few minutes time on stream (see Fig. 8) [16], The coke formed with the Ni catalysts is filamentous. The Ni particle remaining at the tip of the filament hardly deactivates as the coke formed on its surface seems to be transported through the metal particle into the carbon fibre, but the drastic increase in volume causes reactor plugging and prevents use of the still active catalyst (see Fig. 8). The TEM photographs indicate that the carbon filaments have similar diameters to those of the Ni particles. 

The most important polymeric matrices are linear and cross-linked polyesters, epoxy resins and linear and cross-linked polyimides the most important reinforcements are high-performance polymeric fibres and filaments (for polymeric composites), filaments of refractory metals and inorganic materials (E-glass, A12C>3, B, BN, SiC and Carbon) and whiskers (fibrillar single crystals of A1203, B4C, WC, SiC and C, exclusively for reinforcement of metals). 

The formation of filamentous carbon deposits on transition metal catalysts (Fe, Co, Ni) and their alloys have been investigated in some detail over the past two decades.21,38-40 Among them, nickel is the most promising candidate since it forms carbon deposits at temperatures as low as 723-823 K using CH4, C2H6 or CO + H2 feeds. Carbon fibres are usually produced during these reactions. Typical forms of the carbon produced from CH4 decomposition on silica-supported Ni catalysts are shown in Fig. 7.1. The pyrolysis of methane at temperatures somewhat lower than 873 K produces fish-bone type nanofibres.41 The Ni metal particles are present at the tip of each carbon fibre, and catalyse methane decomposition as well as growth... 

It is important to note that diffusion parameters can also depend critically on the dimensions of small particles. A recent model accounts for the formation of hollow filaments, based upon the precipitation of carbon on the catalytic particle. As a result, graphite planes grow parallel to the exterior fibre planes and a hollow core is formed [100]. However, other studies by Boellard et al. [101] on the filament tips where the metal particle is located suggested that the basal planes were positioned at an angle to the filament axis. In this case, the Ni particles were aligned with respect to its [112] axis, parallel to the filament axis (cone-like structures). 

MEDIA STUCTURE Woven (mono-/multi-filament) Non-woven Cartridge Metal/solid fabrication Loose fibres/particles FILTRATION PROPERTIES Particle retention Flow resistanoe Dirt holding oapaoity Tendenoy to biind Cake discharge characteristics Cleanabiiity ... 

Kuraray has also produced heat storing fibres which contain 0.5-40% mixtures of Group VIII transition metal oxide and TiOj at l/(0.3-2.0 ratio). Thus, Septon KL 2002 (hydrogenated isoprene-styrene triblock rubber) containing 15% powder FCjO and 15% powder Ti02 as the core and PET as the sheath were spun at core/sheath = 1/3, stretched, and heat-set to give multifilaments (75 denier/24 filaments), which were plain-woven, scoured, dyed in black and irradiated with a reflector lamp for 40 s at inside temperature 20 °C (inside temperature is the temperature of air between the specimen and a heat insulator in a test apparatus). The fabric showed surface temperature of 54.8 °C and inside temperature 33.0 °C immediately after the irradiation, and 22.0 °C and 25.3 °C, respectively, 5 min after the irradiation. 

---