Granular silicon

The oxidation rate of granular silicon carbide in dry oxygen at 900—1600°C was studied and an equation for the effect of particle size was derived (61). 

Fig. 2.7. Recharge system for a Kayex 150 puller (a) photograph showing a recharge tank (b) the feeder design (top) and the feeding of granular silicon (bottom) (Curtsy of Taisil Electronic Materials Inc., Taiwan)...

Silicon can also be deposited at the surface of hot silicon particles hovering in a fluid bed by pyrolytic decomposition of SiH4 or SiHClo. The result is granular silicon with a purity grade between very good solar and medium semiconductor quality. Compared with the Siemens process, the deposition... 

Ferrocarbo [Carborundum]. TM for briquetted or granular silicon carbide. 

Conditions for the direct oxidation of propylene to acrolein include use of a catalyst of cuprous oxide deposited on granular silicon carbide, catalyst temperature of 375 C, feed stream composition by volume of 20 per cent propylene, 20 per cent air, and 60 per cent steam, and contact time of 1 sec. Recovery and primary purification of the acrolein from the reaction product are effected by quench scrubbing the reactor effluent with water and wth liquid propylene. The composition of the carbonylic compounds in the product is, approximately, acrolein, 90 per cent by weight acetaldehyde, 6 per cent propionaldehyde, 2 per cent and acetone, 2 per cent. At reaction temperatures of about 300 C and conversions of about 50 per cent, a selectivity to acrolein of about 40 per cent is reported for 10 per cent propylene-in-air mixtures. ... 

In addition to antifoam compounds, various modified formulator-friendly antifoams are available. These include encapsulated antifoam compounds. A method of encapsulating antifoam is by placing it into powders that can be made granular. Silicone compound is a translucent liquid, which can be hard to place into powder detergents. Placing the compound on a material that can be ground to a specified particle size makes formulation easier. 

Varistor. A material having an electrical resistance that is sensitive to changes in applied voltage. A typical example is the varistor made from a batch consisting of granular silicon carbide, mixed with carbon, clay and water the shaped components are fired at 1100-1250 C in H2 or N2. 

In the sintering of such materials as silicon nindde, a silica-rich liquid phase is formed which remains in the sintered body as an intra-granular glass, but this phase, while leading to consolidation, can also lead to a deterioration in the high-temperature mechanical properties. 

Silicon is the second most abundant element in the Earth s crust. It occurs widely in rocks as silicates, compounds containing the silicate ion, Si032, and as the silica, Si02, of sand (Fig. 14.33). Pure silicon is obtained from quartzite, a granular form of quartz (another solid phase of SiOz), bv reduction with high-purity carbon in an electric arc furnace ... 

On the other hand, Xiao et al. [215] reported that smooth, dense, and erystalline PbTe films with nearly stoichiometric composition could be obtained by an optimized electrodeposition process from highly acidic (pH 0) tellurite solutions of uncomplexed Pb(II), on Au-coated silicon wafers. The results from electroanalyti-cal studies on Te, Pb, and PbTe deposition with a Pt rde at various temperatures and solution compositions supported the induced co-deposition scheme. The microstructure and preferred orientation of PbTe films was found to change significantly with the deposition potential and electrolyte concentration. At -0.12 V vs. Ag/AgCl(sat. KCl), the film was granular and oriented preferentially in the [100] direction. At potentials more negative than -0.15 V, the film was dendritic and oriented preferentially in the [211] direction (Pig. 3.13). 

The first crystalline silicon was prepared by Henri Sainte-Claire Deville in 1854 ( 9,31). In the course of his researches on aluminum, he decomposed an impure sodium aluminum chloride with the voltaic pile, and obtained a gray, brittle, granular melt containing 10.3 per cent of silicon. When he dissolved away the aluminum, some shining platelets remained. 

Ad 116) Sh. Nakahara et al, JapanP 16147 (1963) CA 60, 6696(1964) (A priming compn for electric detonators is made from a granular mixt of Diazodinitrophenol, fine silicic anhydride, l O-repellent Al silicate, a silicone oil, and a binder, such as NC dissolved in AmOAc) Ad 117) Sh. Nakahara et al, JapanP 16149(1963) CA 60, 15676(1964) (Correction to previous patent) Ad 118) A.E. Lemke, GerP 1158884(1963)... 

Because of technical constraints (several HT samples cannot be cut into 4 cm2 monoliths, due to their granular nature), the MCC-1 test could not be performed with our set of samples. Nevertheless, the normalized apparent dissolution rates of HT materials (r(glass)noll ), approximated as the release rates of silicon (r(Si)norm) obtained by the Strasbourg test (100-125 pm powdered samples), are also shown on Fig. 13 for comparative puiposes. Although not identical, the MCC-1 test and the Strasbourg test can at least be related in terms of their matching efficiencies ( HTmaterial/Eleachant) X corrosion 2.8 day/... 

Five and twenty-three hundredths grams of germanium(IV) oxide (0.05 mol) is dissolved in 15 ml. of a concentrated aqueous solution of hydrofluoric acid (47 %). A platinum evaporating dish or a polyethylene plastic beaker is used to keep silicon contamination to a minimum. A solution of 10.5 g. of barium chloride (0.05 mol) in 50 ml. of water is added. Barium hexafluorogermanate forms as a white, granular precipitate, which is filtered and washed free of chloride. The product is dried by heating to 300° in vacuo and is stored in a desiccator over phosphorus(V) oxide. The yield is 15.24 g. (94%). 

Unless silicates are removed here, they are likely to be confused with Al(OH)3 in the group separation. Repeated evaporation with concentrated HC1 converts silicates into a granular form of hydrated silica, which is readily filtered, particularly after a final digestion with dilute HC1. The precipitate should be subjected to the microcosmic salt bead test or to the silicon tetrafluoride test (Section IV.26). 

Osborne Reynolds was the first to show that tightly packed granular solids expand their volume when deformed.84 This phenomenon is called dilatancy. It is well understood and is discussed in some detail in the literature on soil mechanics.85-87 In vitreous-bonded structural materials such as silicon nitride, dilatancy has been suggested as a contributing factor in the formation of cavities,88 and may be an important factor in the cavitation of ceramic matrix composites.64 Dilatancy has also been suggested as an important factor in controlling the creep and creep relaxation of glass-ceramics.89... 

NIST produce two standard powders for gravity sedimentation. SRM 659 is a silicon nitride powder that has equiaxed particles in the size range 0.2 to 10 pm. SRM 1978 is a zirconium oxide powder of granular irregulary shaped particles in the size range 0.33 pm to 2.19 pm. 

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