Glass and Ceramic Spheres

Glass and ceramic spheres are used extensively in thermoplastics and thermosets. They may be solid or hollow with densities varying from 2.5 to 0.1 g/cm. The spheres 

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In their function as fillers, the organic spheres share the performances and benefits of the spherical form, similar to glass and ceramic spheres. However, their effect on a polymer matrix is normally not the enhancement of mechanical strength, such as tensile strength and abrasion resistance. Instead, they can impart new features to thermoplastics and thermosets, such as reduced density, improved resilience and ductility, mechanical and thermal stress absorption, or enhanced thermal and electrical insulating properties. When added to binders and plastisols for coatings, the function of the spheres can be surface modification of the coated surface this may include the creation of a visual effect or antislip properties, or to make a protective coating [2, 3]. 

The gas-phase mass-transfer coefiicient k a is also affected by both gas and liquid flow rates. Extensive results have been reported by Reiss (R6) for 12.5-, 25-, and 76-mm polyethylene Raschig rings and 25-mm Intalox saddles by Gianetto et al. (G8) for 6-mm spheres, Berl saddles, and glass and ceramic Raschig rings and by Shende and Sharma (S24) for 25-mm... 

These are produced by carbonizing foams made from various binders and micro-spheres. The binders include polyurethane1), resol1121 and novolac39) phenolic oligomers, and epoxy oligomers39), while glass 38), carbon 39), and ceramic 18) micro-spheres fillers have been used for carbonized foams. 

Specchia et al.32 measured gas liquid interfacial area and liquid-phase mass-transfer coefficients in an 8-cm-diameter packed column. Three types of packing, glass spheres, Berl saddles, and ceramic rings, all of 6 mm, were examined. Superficial velocities of 14 through 221 cm s 1 and 0.25 through 4.3 cm s 1 were used for the gas and liquid phase, respectively. The gas-liquid interfacial area was correlated to the pressure drop by an expression... 

Materials for sintering and melting are plastics, metals, or ceramics. Plastics may be unfilled or filled with glass or aluminum spheres or egg-shaped geometries to improve properties like durability and thermal resistance. Also nanoscale particles are used. Unfilled plastics are mostly commodities like semicrystalline polyamides from the PAl 1 or PA12 type or amorphous plastics like polystyrene (PS). Engineering plastics like PEEK are available. 

Ceramic hollow spheres are aluminosUicates produced from a variety of minerals or reclaimed from fly ash waste. Ceramic spheres have higher densities than glass beads, but are less expensive, more rigid, and mechanically more resistant. 

Syntactic foams are made by using a resin matrix to which has been added hollow spheres. The spheres can be made from many different materials including glass, plastic, ceramic, and naturally occurring substances. The most common matrix resins are epoxy and polyester. The foam is made by simply mixing the microspheres into the catalyzed resin, casting a product, and finally allowing it to cure either at room temperature or at an elevated temperature. 

These foams can be defined as composites consisting of hollow microspheres and a polymeric matrix. This one is made of a thermosetting (PU, PIR, PF, EP, silicone or unsaturated polyester) or of a thermoplastic (PE, PP, PVC, PS, polyimide) [56]. The microspheres can be made of silica, glass, carbon, ceramics or polymers such as PS, PE, PP, polyamide (PA), polymethyl methacrylate (PMMA), divinyl benzene (DVB)-maleic anhydride, and so on [56-58]. The diameter of the tiny hollow spheres is 300 mm or less [35]. They contain an inert gas such as nitrogen or a CFC. The properties of these syntactic foams depend on matrix type, microsphere type (and the contained gas), ratio matrix to microspheres, curing process, production technology. Syntactic foams can be made in combination with the conventional ones. Such a complex composite can be formnlated into a mouldable mass then shaped or pressed into cavities. 

Small amounts of inorganic fillers such as fumed silica, high surface area alumina, bentonites, glass spheres and ceramics are mixed with polyols such as propylene glycol to increase viscosity for printed electrodes. Proposed printed electrodes are carbon black, graphite, metallic or plated metaUic particles. 

Name(s) ceramic and glass beads or spheres, fly ash, zeospheres CAS 60676-86-0 (fly ash) 65997-17-3 (glass beads)... 

Finally, metal- and resin-bonded composites are also classified as particulate composites. Metal-bonded composites included structural parts, electrical contact materials, metal-cutting tools, and magnet materials and are formed by incorporating metallic or ceramic particulates such as WC, TiC, W, or Mo in metal matrixes through traditional powder metallurgical or casting techniques. Resin-bonded composites are composed of particulate fillers such as silica flour, wood flour, mica, or glass spheres in phenol-formaldehyde (Bakelite), epoxy, polyester, or thermoplastic matrixes. 

Carrier properties. Carriers can be shaped and configured as films, fibers, planar surfaces, or spheres. Surface morphology, i.e., surface texture and porosity, can exert a decisive influence as can carrier materials the most important are inorganic materials such as ceramics or glass, synthetic polymers such as nylon or polystyrene, and polysaccharide materials such as cellulose, agarose, or dextran. 

Syntactic Foam. Hollow glass, ceramic, or plastic spheres are dispersed in the reactive liquid system before it is cast. When the liquid is polymerized and cured, the hollow spheres make it a unicellular foam. The air bubbles in the cells make it low-density, low dielectric constant and loss, and very resistant to compressive forces such as hydrostatic head in deep-sea equipment. 

As well as these, several industries have their own specifications aggregates [22], porcelain [23], ceramic powders [24], plastics [25], coating powders [26], concrete [27] and metals [28], The standard for glass spheres [29] is designed specifically for sieve analysis of glass spheres used in reflective road and pavement markings and other industrial uses. 

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