Fine yields materials

For very fine particles with intimate surface contact, these relatively weak secondary adhesive forces can be quite significant. For example, Rumpf [1] has estimated the contributions of van der Waals and electrostatic forces in agglomerates of fine-grained material. The calculations were made for quartz glass and yielded a binding force due to van der Waals forces between two spheres given by ... 

Catalyst preparation and inspection by microscopy. Preparation by impregnation with ammonium iron citrate and iron nitrate resulted in a homogeneous iron distribution as determined by light microscopy. Ammonium iron EDTA as a precursor yielded an eggshell distribution of the iron compound. Finely divided material deposited on the support was observed with Transmission Electron Microscopy in all catalysts. Tn addition to this, some material deposited next to the support was observed in catalysts ex nitrate. It was therefore decided to focus on the catalysts prepared with ammonium Fe(ITI) citrate. 

The product (52 g) from the previously described reaction is dissolved in 600 mL of methanol at reflux temperature and filtered hot to remove some intractible brown material. The filtrate is diluted to 600 mL with methanol and the solution is reheated to reflux. Water (400 mL) is added to the hot solution, which is then stirred and cooled to room temperature. The wliite finely powdered material that precipitates is the pure meso isomer. It is removed from the mixture by filtration, washed with cold water, and dried in vacuo over P4O10. The yield is 20-23 g (30-34%). Anal. Calcd. for Ci6H36N4 2H20 C, 60.00 H, 12.50 N, 17.50. Found C, 60.11 H, 12.58 N, 17.27. 

No large single crystals for X-ray diffraction are available, and the fine-grained material yields poor powder diffraction patterns. 

Pastes. Fluid gels may to some extent be suitable models for various foods that can be described as pastes, i.e., systems that have a yield stress but are readily deformable and that contain finely dispersed material. Anyway, the qualitative relations listed above for fluid gels also apply to most pastes. We will briefly mention some of the numerous foods in this category. 

The diagram also indicates that phosphate should precipitate in basic soils as one of several Ca phosphates, the least soluble of which are hydroxy- and fluoroapatite. Variscite and strengite are too soluble to exist under basic conditions, and they should not form in basic soils. Both variscite and strengite, in fact, would be good phosphate fertilizers in alkaline soils because of their solubility in basic soils, if they were applied as finely ground materials. Calcium phosphate ore ( rock phosphate, mostly hydroxy- and fluoroapatite) is similarly effective in acid soils. Rock phosphate is treated with sulfuric acid to make superphosphate, nominally CaHP04 treatment with phosphoric acid yields triple superphosphate, nominally Ca(H2P04)2. Both superphosphate and triple superphosphate are more soluble than rock phosphate and make phosphate more immediately available when added to soils at any pH. 

The systems shown in Fig. 6.8-31 have been often used to render smaller roller presses suitable for the briquetting of very fine aerated materials, such as magnesium oxide from seawater precipitation. If presses with larger roller diameters (e.g.,> 1000 mm) are used and the material is fed hot, directly from the rotary hearth calci-ner, a high yield of briquettes with excellent density is obtained and only a very small... 

Structural formers (oxides, carbides, nitrides, salts of organic acids, fine-dispersed powders, surfactants) exert an effect on the permolecular structure formation and assist in yielding materials with a given microstructure. A number of powder Cl can be related to active structuring agents. In particular, impregnation of small amounts of fine-dispersed Cl (NDA, G-2, 5-PhTet) in the polymer film materials improves their strength and barrier properties (see Sect. 2.3). 

A solution of sodium cyanate is made by mechanically stirring the finely powdered material with water at 50° (100 ml. of water for each 15 g. of material). Glacial acetic acid is added until the solution is neutral to phenol-phthalein. After filtration, the solution is allowed to stand in a refrigerator for a few hours. Then the crystals are collected and washed with alcohol. Yield 5 g. (33 per cent). The substance is thoroughly dried in a vacuum desiccator to avoid partial hydrolysis on storage. 

The influence of chloride and sulfate concentration, and to a lesser extent particle size, is dependent on the quantity of moisture. The laboratory experiments yielded similar corrosion rates to those measured within a bulk carrier (ship) cargo hold. Based on this, and the porous texture and dustiness of coal and iron ore cargo, it is proposed that the corrosion rate of mild steel in contact with coal or iron ore cargo is dominated by the fine particle material that is deposited from the larger particles. 

The sHde block (Saint-Venant body) simulates ideal plastic behavior with no strain at aU below a critical yield stress 0 (Figure 2.10), although at and above the critical yield stress the strain increases without Hmit This behavior is frequently invoked in problems of slope stabihty for wet fine-grained materials such as silt and clay, as the sHde block wiU not move due to friction until sufficient stress is applied. 

A very rapid oxidative disintegration of chromium-bearing minerals, rocks and alloys is obtained by fusing or sintering the finely pulverized material with potassium bifluoride (platinum spoon). Potassium chromate results and may be detected by means of the diphenylcarbazide reaction. The fluoride disintegration is particularly recommended for the detection of chromium in steels or special alloys, which are likely to contain molybdenum. The latter, in the form of molybdate ions, reacts with diphenylcarbazide to yield a red-violet color and thus impairs the test for chromium. However, the fluoride method yields no M0O4" ions, but instead complex [M0O3F2] ions, which do not react with diphenylcarbazide. 

R.A. Masumura, P.M. Hazzledine, C.S. Pande, Yield stress of fine grained materials. Acta Mater. 46(13), 4527-4534 (1998)... 

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