Liquid metal atomization

Many droplet size distributions in natural droplet formation and liquid metal atomization processes conform to lognormal distribution ... 

Small metal particles are produced by mechanical comminution, chemical reaction, electrolytic deposition, and liquid-metal atomization ... 

Different methods for the production of metal powders including mechanical commuting, chemical reaction, electrolysis, and liquid metal atomization are used in practice [1]. Powders of about 60 metals can successfully be produced by electrolysis. The majority of metallic powders are obtained by molten-salts electrolysis. However, due to technological advantages and various industrial applications most of the practically useful powders, e.g., copper, iron, and nickel, are produced from aqueous solutions [3]. 

Some metals are soluble as atomic species in molten silicates, the most quantitative studies having been made with Ca0-Si02-Al203(37, 26, 27 mole per cent respectively). The results at 1800 K gave solubilities of 0.055, 0.16, 0.001 and 0.101 for the pure metals Cu, Ag, Au and Pb. When these metal solubilities were compared for metal alloys which produced 1 mm Hg pressure of each of these elements at this temperature, it was found drat the solubility decreases as the atomic radius increases, i.e. when die difference in vapour pressure of die pure metals is removed by alloy formation. If the solution was subjected to a temperature cycle of about 20 K around the control temperamre, the copper solution precipitated copper particles which grew with time. Thus the liquid metal drops, once precipitated, remained stable thereafter. 

In liquid metal solutions Z is normally of the order of 10, and so this equation gives values of Ks(a+B) which are close to that predicted by the random solution equation. But if it is assumed that the solute atom, for example oxygen, has a significantly lower co-ordination number of metallic atoms than is found in the bulk of die alloy, dieii Z in the ratio of the activity coefficients of die solutes in the quasi-chemical equation above must be correspondingly decreased to the appropriate value. For example, Jacobs and Alcock (1972) showed that much of the experimental data for oxygen solutions in biiiaty liquid metal alloys could be accounted for by the assumption that die oxygen atom is four co-ordinated in diese solutions. 

The metallic bond, as the name says, is the dominant (though not the only) bond in metals and their alloys. In a solid (or, for that matter, a liquid) metal, the highest energy electrons tend to leave the parent atoms (which become ions) and combine to form a sea of freely wandering electrons, not attached to any ion in particular (Fig. 4.8). This gives an energy curve that is very similar to that for covalent bonding it is well described by eqn. (4.4) and has a shape like that of Fig. 4.6. 

The Atomic Energy Act of 1946 represented the interests of American scientists who wished to see nuclear energy developed for nonniilitai y purposes. It called for the establishment of a five-member civilian Atomic Energy Commission (AEC), which could deliver weapons to the military only on presidential order. But the militaiy tensions ot the early Cold War delayed civilian nuclear power development until 1948, at which time 80 percent of the AEC s budget went to militaiy ends. In 1951, U.S. civilian nuclear power development consisted of only a small experimental government (liquid metal) reactor in Idaho. 

Miller, E. C., Chapter 4 of Liquid Metals Handbook, US Atomic Energy Commission, Navy Dept., Washington, D.C., 144-183 (1952)t... 

Miller, E. C., in Liquid Metals Handbook (ed.-in-chief, R. N. Lyon), Atomic Energy Comm, and Dept, of the Navy, Washington DC, June, 144 (1952)... 

The simplest transition metal carbonyls are mononuclear of the type M(CO)x, in other words those with only one metal atom. They are hydrophobic but soluble to some extent in nonpolar liquids, such as n-butane or propane. The dinuclear carbonyls are more complex but have the same general characteristics as the mononuclear carbonyls. The carbonyls, which are or could be used in CVD, are listed in Table 3.4 with some of their properties. 

An interesting reaction involves the cocondensation of transition-metal atoms with liquid methylphenylsiloxane polymers at -20 to 0°C... 

A method has recently been described for wrapping polymers around metal atoms and very small metal clusters using both matrix and macroscale metal vapor-fluid polymer synthetic techniques. Significant early observations are that (i) the experiments can be entirely conducted at, or close to room temperature, (ii) the resulting "pol5aner stabilized metal cluster combinations are homogeneous liquids which are stable at or near room temperature, and (,iii) the methodology is easily extended to bimetallic and trimetallic polymer combinations. ... 

Figure 4.28 shows an example where STM recognizes the individual metal atoms in an alloy, thus revealing highly important structural information on the atomic level. The technique does not require a vacuum, and can in principle be applied under in situ conditions (even in liquids). Unfortunately, STM only works on well-defined, planar, and conducting surfaces such as metals and semiconductors, and not on oxide-supported catalysts. For the latter surfaces, atomic force microscopy offers better perspectives. 

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