Melt, solidification

Molten solutions can also be used for crystallization. Fluxes are selected that have a high solubility of the to-be crystallized material. Borate fluxes are used for some oxide systems, sodium sulfide fluxes are used for sulfide systems, and molten metal fluxes are used for carbide and nitride systems. In both the melt and flux systems, the solubility is highly temperature dependent. The solubility in flux systems is not particularly well known except for a few systems. The general solubility behavior is like that in liquid phase precipitation, which was discussed in Chapter 6. In melt solidification, the supersaturation, S, is given by 

Solidification is discussed in the book Transport Phenomena in Metallurgy [9]. The freezing time for a volume, V, with a svirface area. A, exposed to cooling is given by the time, t, required to transfer the heat of fusion  

Chapter 8 Other Ceramic Powder Fabrication Processes 

The size of the crystalites produced will depend on the nucleation rate and crystal growth rate at the solidification front. Both are controlled by the local supersaturation. The rate expressions for homogeneous nucleation (equation (6.15)) and heterogeneous nucleation (equation 

This chapter has given information on several other methods of ceramic powder synthesis not easily dassified into the chapters on solid, liquid, and gas phase synthesis. These methods include spray 

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While this may appear even more cumbersome than Eq. (3.41), it contains some parameters that are directly measurable such as the interfacial surface energy, y, and the heat of fusion, AH, but more importantly, it contains the temperature difference (T, — T), which is the degree of undercooling—that is, how far the temperature is below the melting (solidification) point ... 

For reversible transformations such as melting/solidification or the Q to (3 quartz inversion in silica, heat flux DSC and power compensated DSC can each be equivalently precise in determining the latent heat of transformation. Transformations of... 

Melt solidification, sol-gel reactions, Czochralski, and floating-zone methods... 

Solid state reactant Thermal decompositions of a solid Oxidation or reduction of a solid Precipitation Solution heating or cooling Evaporative salting-out Chemical reaction with insoluble product Hydrothermal synthesis Forced insolubility Dissolution reprecipitation Evaporative Condensation Gas phase reaction with solid product Thermal decompositions Oxidation or reduction reactions Combination reactions with a solid product Solvent removal Spray drying Freeze drying Spray roasting Sol-gel synthesis Melt solidification... 

The mineralogy of CAIs is commonly described in terms of what might be called primary and secondary minerals. Although useful, these terms are relative and potentially misleading. Primary refers to a phase that apparently formed when the inclusion itself first formed, for example, by direct condensation, melt solidification, or solid-state recrystallization. Secondary is a petrographic term for any phase that texturally appears to be replacing another phase e.g., one that not only mantles... 

J. R. (1991b) Melt solidification and late-stage evaporation in the evolution of a FUN inclusion from the Vigarano C3V chondrite. Geochim. Cosmochim. Acta 55, 621-637. 

F reezing (melting) -> Solidification of a liquid (liquefaction of a solid)... 

Describe melting, solidification, sublimation, and deposition in molecular terms... 

The solidification of the polymer melt in rotational molding is relatively slow, in comparison to other processes, and is estimated to be in the range of 10-30°C/min. Moreover, the melt solidification is gradual and nonuniform across the molded part thickness, leading to important variations in the morphological features, as illustrated in Fig. 9, and dictating the properties and overall performance of the final product. The effects are more dramatic for resins with slower crystallization rates, such as polypropylene, compared to that observed with polyethylene. 

The S—A-S mixtures should be prepared and mixed while the materials are between about 260 and 320°F. The former represents the melting (solidification) point plus a tolerance to avoid sulfur structuring effects, and the latter is the temperature above which sulfur undergoes an abrupt and very large increase in viscosity as shown in Figure 2. Although these viscosity changes are perfectly reversible (2), they do adversely affect the workability of the mix above about 325°F. However, as will be shown later, acceptable mixes were prepared at sulfur temperatures... 

Beading [n.] Formation of bead-like particles typical in solidification of melt droplets. (See also prilling, pastillation, melt solidification.)... 

In pressure agglomeration, the distance between the surfaces of compacting tool sets specifically in extrusion, the distance between the pressure generating device and the die plate, in roller presses, the closest distance between the rollers. Double-roll pellet mill in which the rollers are in the shape of coarse, intermeshing gears with bores at the root sections between the gear teeth. (Also gear pelletizer.) Distribution plate in which the perforations are manufactured such that they produce a directional flow of gas. See melt solidification. 

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