The production of metallic glasses

Traditionally, production of metallic glasses requites rapid heat removal from the material (Fig. 2) which normally involves a combination of a cooling process that has a high heat-transfer coefficient at the interface of the Hquid and quenching medium, and a thin cross section in at least one-dimension. Besides rapid cooling, a variety of techniques are available to produce metallic glasses. Processes not dependent on rapid solidification include plastic deformation (38), mechanical alloying (7,8), and diffusional transformations (10). 

Zinc phosphate, Zn2(P0 2> forms the basis of a group of dental cements. Chromium and zinc phosphates are utilized in some metal-treating appHcations to provide corrosion protection and improved paint adhesion. Cobalt(II) phosphate octahydrate [10294-50-5] Co2(P0 2 8H20, is a lavender-colored substance used as a pigment in certain paints and ceramics. Copper phosphates exhibit bioactivity and are used as insecticides and fungicides. Zinc, lead, and silver phosphates are utilized in the production of specialty glasses. The phosphate salts of heavy metals such as Pb, Cr, and Cu, are extremely water insoluble. 

Antimony trioxide occurs in nature as minerals, valentinite [1317-98-2] and senarmontinite [12412-52-1]. It is used as a flame retardant in fabrics as an opacifier in ceramics, glass and vitreous enamels as a catalyst as a white pigment in paints as a mortar in the manufacture of tartar emetic and in the production of metallic antimony. 

Other top-down methods are used for the production of ultrafine-grained (UFG) metals and alloys. These include the devitrification of metallic glass and severe plastic deformation, in which a coarse-grained poly crystalline metal or alloy is subjected to large shear strains under pressure, forcing the grains to subdivide into nanosized... 

Industry has applied radiotracers in a very large variety of ways. More than half of the SOO largest manufacturing concerns in the United States use radioisotopes in the production of metals, chemicals, plastics, pharmaceuticals, paper, rubber, clay and glass products, food, tobacco, textiles, and many other products. Radioisotopes are used to study mixing efficiency, effect of chamber geometry, residence time in reactors, flow rates and patterns in columns and towers for fractionation, absorption, racemization, etc. Some of die many uses are listed in Table 9.6 and a few are described below to reflect the scope and value of the industrial applications of radioisotopes. Quite often the radionuclide used is not isotopic with the system studied. 

The capacity of metal, glass, or salt baths for continuous operation differs from that of batch-type (dipping) baths because the coefficient of heat transfer is increased by the movement through the bath of the strip or pieces being coated. That movement also enhances temperature uniformity as well as finished product quality. 

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