Melting point materials

During the production of mineral oils from vacuum distillates, one of the process steps, dewaxing , removes the high melting point materials in order to improve the oil s pour point. Dewaixing produces paraffins and waxes, the first coming from light distillates, and the second from medium or heavy distillates. 

The thennal evaporation source was the earliest used to produce metal clusters in the gas phase [H, 12 and 13], mostly for clusters of the alkalis and other low melting point materials. In this technique, a bulk sample is simply... 

Skull Melting. Skull melting, or the cold cmcible technique, is used for high melting point materials. Zirconia [1314-23 ] has such a... 

Kletz. T. A. 1982. A Flame Trap Assembly for Use with High Melting Point Materials. Plant/Operations Progress, 1(4), 252-254. 

For low melting-point metals (for example, solder materials), the liquid metal and the atomization gas may be mixed internally inside the atomizer for both low and high melting point materials, the two fluids can be mixed externally outside the atomizer in the nearnozzle region. 

Another method to obtain enthalpies of formation of compounds is by solute-solvent drop calorimetry. This method was pioneered by Tickner and Bever (1952) where the heat formation of a compound could be measured by dissolving it in liquid Sn. The principle of the method is as follows. If the heat evolved in the dissolution of compound AB is measured, and the equivalent heat evolved in the dissolution of the equivalent amount of pure A and B is known or measured, the difference provides the enthalpy of formation of the compound AB. Kleppa (1962) used this method for determining enthalpies of formation of a number of Cu-, Ag- and Au-based binaries and further extended the use of the method to high-melting-point materials with a more generalised method. 

Equation (4.4) shows that the melting point is an important determinant in solubility calculations, the lower the melting point, the lower the inter-molecular forces, and therefore the easier it is for the drug to dissolve in the intercellular lipids of the skin. It is interesting to note that two of the successful transdermally delivered drugs, nitroglycerin and nicotine, are low melting point materials. 

High-temperature corrosion problems are experienced mainly by boilers firing residual fuel oils. The corrosion is due primarily to the presence of vanadium, sodium, and sulfur compounds in the fuel oil (vanadium can be as high as 500 ppm, Na 300 ppm, and sulfur 40,000 ppm). During combustion the presence of these compounds react and give rise to complex low-melting-point materials that deposit on heat-transfer surfaces and supporting structures see reactions (17.1)—(17.3) (Niles and Sanders, 1962) ... 

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