Copper with metallic particles

Most polymers can be filled with metal particles to render them conductive. However, consideration must be given to spedfics of the possible combinations [62]. For example, ABS and PC are widely used for instruments, TV, and similar housings but copper is known to promote degradation of PC so another filler is often preferable [63],... 

Better conductivity than with carbon black can be achieved with metal particles. Common are copper or aluminum in the form of powder or flakes, as well as brass, carbon, and stainless steel fibers. To increase the effective surface, electrically neutral filler particles are coated with metal, e.g., nickel-plated glass fibers or small spheres, silver or nickel-coated mica or silicates [23, 27, 29]. 

This reaction is carried out in tall fluidized beds of high L/dt ratio. Pressures up to 200 kPa are used at temperatures around 300°C. The copper catalyst is deposited onto the surface of the silicon metal particles. The product is a vapor-phase material and the particulate silicon is gradually consumed. As the particle diameter decreases the minimum fluidization velocity decreases also. While the linear velocity decreases, the mass velocity of the fluid increases with conversion. Therefore, the leftover small particles with the copper catalyst and some debris leave the reactor at the top exit. 

In the effect of active metal, copper was more stable and active than silver and zinc. In the effect of particle size, the smaller particle is the more stable and active. It seems that the catalysts with smaller particle size have more active sites compared with those of larger particle size in same space. Through out the Fig. 3 and Table 2, in the effect of reaction... 

Similarly, Pd, Ag, and Pd-Ag nanoclusters on alumina have been prepared by the polyol method [230]. Dend-rimer encapsulated metal nanoclusters can be obtained by the thermal degradation of the organic dendrimers [368]. If salts of different metals are reduced one after the other in the presence of a support, core-shell type metallic particles are produced. In this case the presence of the support is vital for the success of the preparation. For example, the stepwise reduction of Cu and Pt salts in the presence of a conductive carbon support (Vulcan XC 72) generates copper nanoparticles (6-8 nm) that are coated with smaller particles of Pt (1-2 nm). This system has been found to be a powerful electrocatalyst which exhibits improved CO tolerance combined with high electrocatalytic efficiency. For details see Section 3.7 [53,369]. 

An obvious means of increasing conductivity is to incorporate metals into the fabric. Thus fabric can be sprayed with a liquid resembling metallic paint, containing micron-sized metallic particles such as copper incorporated into a binder such as a polyester, epoxy or acrylic resin. During curing the metallic particles come into contact with one another, thus... 

This filler is mined, ground and sieved to a particle size less than 100 mesh and used as an inert diluent and cheapening filler for rubber compounds. It is usually off-white to cream in colour. Depending upon source, the filler can be contaminated with metal ions, e.g., iron, copper, manganese, which can catalyse oxidation. It can be used in very high loadings with great effect on compound hardness. 

Soldier crabs (Mictyris longicarpus) accumulate copper mostly from sediments rather than the water column (Weimin et al. 1994). The fine particles of sediment trapped as food contain bio-available fractions of copper and other metals, and these significantly correlate with metal concentrations in the body of the crab. However, copper accumulations from sediments by soldier crabs... 

Figure 6.20 shows an example in which QEXAFS has been used in combination with XRD to study the temperature programmed reduction of copper oxide in a Cu/ZnO/Al203 catalyst for the synthesis of methanol [43,44]. Reduction to copper metal takes place in a narrow temperature window of 430-440 K, and is clearly revealed by both the EXAFS pattern and the appearance of the (111) reflection of metallic copper in the XRD spectra. Note that the QEXAFS detects the metallic copper at a slightly lower temperature than the XRD does, indicating that the first copper metal particles that form are too small to be detected by XRD, which requires a certain extent of long range order [43,44],... 

At low water content from vv = 2 to 5.5, a homogeneous reverse micellar solution (the L2 phase) is formed. In this range, the shape of the water droplets changes from spheres (below ir = 4) to cylinders. At tv — 4, the gyration radius has been determined by SAXS and found equal to 4 nm. Syntheses in isolated water-in-oil droplets show formation of a relatively small amount of copper metallic particles. Most of the particles are spherical (87%) with a low percentage (13%) of cylinders. The average size of spherical particles is characterized by a diameter of 12 nm with a size polydispersity of 14%. 

At vv = 30, the isotropic phase remains in equilibrium with isooctane and is attributed to the L2 phase, similar to that obtained at lower water content (in the range of vv = 5.6 to 11). By increasing the water content from w = 30 to 35, the interconnected cylinders network is diluted with a decrease in the number of connections. Over all this water content range, formation of spherical and cylindrical copper metallic particles are observed. At vv = 34, as at lower water content, cylindrical (42%) and spherical (58%) nanoparticles are observed. The average diameter of spherical particles observed in most of the cases is 9.5 0.9 nm. The length and width of the cylinders are 19.8 2.7 nm and 6.5 0.8 nm, respectively. 

The powder turns blue if it contains traces of metals or if it is in contact with such metals as iron, copper, zinc, etc. Traces of metals present in powder sometimes cause the formation of blue stains around the metallic particles. A blue coloration appears sometimes at the points where the powder is in contact with metal on the inner surface of cases lined with metal. 

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