Melt stirring

For this preparation, it is particularly necessary that the sodium acetate should be free from traces of water. The anhydrous material can be prepared by gently heating the hydrated salt (CHsCOONa,3HjO) in an esaporating-basin over a small Bunsen flame. The salt dissolves in its water of ciystallisation and resolidifies as this water is driven off further heating then causes the anhydrous material to melt. Stir the molten anhydrous material to avoid charring, and then allow it to cool in a desiccator. Powder the cold material rapidly in a mortar, and bottle without delay. 

Significant improvement of tantalum powder properties was achieved by the application of molten alkali halides as solvents for potassium heptafluorotantalate, K2TaF7. Variation of the initial concentration of K2TaF7 in the melt, stirring and rate of sodium loading enable a well-controllable production of tantalum powder with a wide variety of specific charges. Heller and Martin [590] proposed the use of a reactor equipped with a stirrer in 1960. Fig. 142 shows a typical scheme of the reactor [24, 576]. All metal parts of the reactor are made of nickel or nickel alloy. 

A novel reactor for pyrolysis of a PE melt stirred by bubbles of flowing nitrogen gas at atmospheric pressure permits uniform temperature depolymerisation. Sweep-gas experiments at temperatures 370-410 C allowed pyrolysis products to be collected separately as reactor residue (solidified PE melt), condensed vapour, and uncondensed gas products. MWDs determined by GPC indicated that random scission and repolymerisation (crosslinking) broadened the polymer-melt MWD. 19 refs. USA... 

The experimental apparatus used consisted of a stationary metal atom-vapor reactor which has been detailed in the literature earlier. (39) Metal was evaporated (-0.1 to 0.5 g) and codeposited at -196°C with excess organic solvent vapor (- MO-150 mL). The frozen matrix was allowed to warm under controlled conditions, and upon melting stirring was commenced. After warming to room temperature stable colloidal solutions were obtained and syphoned out under N. ... 

Figures 12.1 and 12.2 for the fusion arrangement. Pipette 4 mL of strontium carrier and 1 mL of barium carrier onto the sample. Add 1 mL of 2 M Ca(N03)2 solution. Add 25 g of NaOH pellets. Carefully heat over Meeker burner for 30 minutes. Remove from heat and slowly add 2.5 g of Na2C03 to the hot melt, stir with nickel stirring rod, and continue heating the clear melt for 30 minutes to convert calcium, strontium, barium, and radium salts to carbonates.

Heat to 70°C to melt, stir until homogenous, and cool to 60°-65°C. 

Syp08ulphite of Soda. Mix together 1 nound dried carbonato of soda and 16 ounces nowers of sulphur, and slowly heat the powder iu a porcelain dish until the sulphur melts stir freely, to expose it to the atmosphere, until tho incandescence flags, then dissolve the mass in water, and immediately boil the filtered liquid with some flowers of aalphur laatly, carefully concentrate the solution for cryst Uzatiun. ( Cooley.)... 

A modification of melt stirring, termed compocasting (or rheocasting), is used to obtain a suitable slurry by employing powerful agitation of a semisolid (two phase) alloy to yield a non-dendritic phase, which imparts thixotropic properties. The mix is then infiltrated to produce a near net shape component [138-139]. It is desirable that the alloy has a wide solidification range in which it exists as a semisolid. The volume fraction of carbon fiber is restricted to about 20% to obtain effective dispersion. 

Due to the fact that ternary crystals need to be grown under low temperature gradient, melt stirring during growth becomes very important and necessary for many purposes ... 

Fig. 12.9 Radial InSb profiles in 50-mm diameter GalnSb wafer measured from the center (0 mm) to the edge (25 mm) (a) without melt stirring and (b) with melt stirring using ACRT. The temperature gradient near the melt/solid interface was 25-30°C/cm.

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