Commercial alloy production

Tungsten is recovered mostly from mineral scheebte and wolframite. The recovery process depends on the mineral, the cost, and the end use i.e., the commercial products to be made. Typical industrial processes have been developed to convert tungsten ores to tungsten metal and alloy products, tungsten steel, non-ferrous alloys, cast and cemented tungsten carbides, and tungsten compounds. A few processes are mentioned briefly below. 

Cold-working is frequently used for hardening of commercial metal products. Thus, piano wire and the wire used in bridge construction obtain their hardness as a result of (he final wire drawing operations. Sheet stock is often supplied in different degrees of hardness obtained by cold-rolling to the desired hardness. Mechanical working is sometimes the only feasible way lo harden specific metals and alloys. 

The project goals are to significantly improve both the kinetic performance of the electrocatalyst powder at low noble metal loading and its utilization in the cathode layers through layer structure development. Limitations in the catalyst performance will be addressed through combinatorial discovery of supported catalyst compositions and microstructures. The discovery of these new catalyst formulations will be carried out under conditions that have been scaled for commercial powder production. A large variation of binary, ternary and quaternary noble metal -transition metal alloys and mixed metal-metal oxide catalyst compositions will be screened. To improve the utilization/performance of the catalyst in MEAs,... 

Ternary Alloys. Almost all commercial alloys are of ternary or higher complexity. Alloy type is defined by the nature of the principal alloying additions, and phase reactions in several classes of alloys can be described by reference to ternary phase diagrams. Minor alloying additions may have a powerfiil influence on properties of the product because of the influence on the morphology and distribution of constituents, dispersoids, and precipitates. Phase diagrams, which represent equiHbrium, may not be indicative of these effects. 

Since the introduction of BPA polycarbonate homopolymer, researchers have continually sought to expand the usefulness of these materials via synthesis of new polycarbonate homo- and copolymers. This section will focus on the copolymers that are commercially available. For a more extensive examination of noncommercial, non-BPA polycarbonates, several excellent reviews may be found at [90-93]. Copolymer production generated by reactive blending, coextrusion, and/or compatibilizing materials (e.g., grafting) will also not be discussed. However, a historical overview of commercial alloys and blends may be found in a recent work by Utracki [94]. 

Wrought aluminum products are produced by all of the standard hot- and cold-working processes. In general, the commercial alloys and tempers cross product lines. As such the main effect of various products on corrosion is that attributable to variations in grain structure, as discussed in the previous section. 

In agreement with Eq. (5-29), Barrett and Lowell (1975) concluded from their study of the cyclic oxidation behavior of various commercial alloys at 1150 °C that the most critical factor in minimizing scale spallation is to keep the scale as thin as possible. They reported that Cr203-forming alloys with the most complex compositions tend to spall the most owing to the formation of thicker scale products. 

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