Melting of metals

Atomization of melts has been used in two principal areas, i.e., powder production 4] and spray forming, 3] as shown in Figs. 1.4 and 1.5, respectively. It is not until recent years that the technologies for the atomization of melts have advanced sufficiently to ensure good yields of usable products over sustained periods of plant operation. In these two areas, some aspects such as melting of metals or alloys, basic atomizer designs, and atomization mechanisms are the same or similar. Metals or alloys melt at high temperatures to produce low viscosity but usually... 

Potential hazards associated with electron beam vacuum melting of metals include the possibility of ignition of metal aerosols or condensate films in the event of sudden loss of vacuum at elevated temperatures. 

Primitive achondrites exhibit metamorphic textures, as appropriate for the solid residues from which melts were extracted. In effect, these meteorites represent an extension of the highly metamorphosed type 6 chondrites, which show no eutectic melting of metal and sulfide. In a few cases, some primitive achondrites have recognizable chondritic textures, but often they are so thoroughly recrystallized that chondrules are not identifiable. 

For preparation of alloys nickel by cleanliness of 99.99 %, magnesium by cleanliness of 99.95 %, lanthanum by cleanliness of 99.79 %, and mishmetall (industrial mixture of rare-earth metals (REM) Ce - 50, La - 27, Nd - 16, Pr - 5, others REM - 2wt. %) were used. The melting of metal charge was carried out in the vacuum-induction furnace under fluxing agent from eutectic melt LiCl-KCl. The composition of alloys was supervised by the chemical analysis and the X-ray testing. 

Mixtures of clay and graphite are used very largely in the crucibles employed in the melting of metals. Here the graphite contributes toward the refractoriness and heat conductivity of the mass, prevents the oxidation of the metal, and produces a smooth surface for pouring. 

By and large we can consider the interest in the problem of the ultrasonic treatment of melts of metals and alloys by the quantity of published works. Thus, the well-known review by Hiedemann (1954) [1] contains 120 references, mainly reflecting the investigations performed before World War II, our monograph [5] written in 1965 reveals about 260 original works and patents on UST, while in 1988 when we prepared the second edition of the monograph [5] the quantity of published works was even higher. 

Flux.—A sxibstance or mixture used to facilitate the melting of metals or minerals, as glass, borax, and the like. 

Regulation limiting dioxin and furan emissions from the melting of metals. 

Direct Tooling by sintering and melting of metals can be regarded as the most important process to make tool components to be integrated in the final tools. 

Fig. 4. Melting of metals as function of the heating rate 6 (peak onsets).

We have obtained the relation, analogous to Eq.(l), that gives the true temperature of the calorimeter cup lids, T Ct), as a function of the programmed temperature Tp(t) and heating rate T. The relation was derived from measurements made at various heating rates of differences in the programmed temperatures for melting of metallic standards placed on the bottom and lid of the sample cup. ... 

Melts of metals as well as crystalline ceramic oxides have low viscosities. All solidify at a sharp melting point and their viscosity above the melting point increases rapidly and then reaches a viscosity comparable to that of motor oil at room temperature, i.e., log <0.2 poise. Yet, fiber formation from the liquid phase requires a viscosity of log 2.5 to log 3.0 poise. Only liquid droplets are formed if a low viscosity liquid is extruded at a normal quench rate of -10" K/s through an orifice, spinneret hole or bushing tip. To facilitate fiber formation, the viscosity must be raised from log <0.2 poise to log 2.5 to log 3.0 poise. This can be achieved by one of two generic routes, i.e., by a rapid solidification (RS) or an inviscid melt spinning (IMS) process. 

X.J. Chen, A.C. Levi, E. Tosatti, Hamaker-constant calculations and surface melting of metals, semimetals and semiconductors. Nuovo Cimento D, 13(7), 919-937 (1991). doi 10.1007/ BF02457179... 

Heat-resistant steels are treated extensively in [1.52], creep data are compiled in [1.86]. Steels are considered heat-resistant if they possess-in addition to good mechanical properties at ambient temperature-special resistance against short or long term exposure to hot gases, combustion products and melts of metals or salts at temperatures above about 550 °C where non- or low-alloyed steels are no longer applicable due to extensive scaling and creep. 

Slag By-product consisting of impurities produced during the refining of ore or melting of metal. 

---