Crystal columnar

Nickel—Iron and Cobalt—Iron Alloys. Selenium improves the machinabifity of Ni—Ee and Co—Ee alloys which are used for electrical appfications. Neither sulfur nor tellurium are usefiil additives because these elements cause hot britdeness. The addition of 0.4—0.5% selenium promotes a columnar crystal stmcture on solidification, doubling the coercive force of cobalt—iron-titanium alloy permanent magnets produced with an equiaxial grain stmcture. 

Columnar crystals growing into solution from mould walls... 

Steps, or growth layers, are structure components for construction of a variety of growth forms in the electrodeposition of metals (e.g., columnar crystals, whiskers, fiber textures). We can distinguish between monoatomic steps, polyatomic microsteps, and polyatomic macrosteps. Only the propagation of polyatomic steps can be observed directly, in situ. 

C. P. Rammelsberg prepared what appears to be nickel tetrammino-iodate, Ni(I03)2.4NH3, as a pale blue crystalline powder, by the addition of alcohol to a soln. of nickel iodate in ammonia he also prepared a similar cobalt tetrammino-iodate, Co(I03)2.4NH3. P. Ephraim and A. Jahnsen prepared trihydrated nickel pentammino-iodate, Ni(I03)2.5NH3.3H20, in reddish-violet columnar crystals, and from it they obtained pale violet crystals of nickel pentammino-iodate, Ni(I03)2.5NH3, of sp. gr. 2-97, and with a dissociation press, of 179 mm. at 53° 365 min. at 65° 670 at 77° and 905 mm. at 79°. The ammino-iodates do not explode when heated in open tubes, but they do so in closed tubes between 210° and 219°. The mol. vol. of the pentammino-salt is 166 2, and the mol. vol. of each NH3 is 17 1. The heat of formation of the pentammine is 12-5 Cals. 

In weld-overlay cladding, the solidifying melt forms columnar crystals perpendicular to the wall surface. Along the grain boundary of these crystals, the corrosion resistance is lower than in the rolled material. In the case of heavy corrosion, at least a two-layer weld-overlay cladding should therefore be selected. 

Fifty grams of silver nitrate are treated with 155ml of molar sulfuric acid and gently heated in an evaporating dish under the hood until no more add vapors are given off. The perfectly dry cold residue is dissolved in the minimum amount of concentrated aqueous ammonia and allowed to crystallize in a desiccator. The crude product is recrystallized from 5% aqueous ammonia and dried in air large colorless columnar crystals. 

Selenoformaldehyde, H.CHSe.—Hydrogen selenide is passed for 2 5 to 3 hours into a 36 per cent, aqueous solution of formaldehyde mixed with three times its volume of concentrated hydrochloric acid.1 The resulting product separates from alcohol in columnar crystals, M.pt. 215° C. (approx.). It is sparingly soluble in most organic solvents, and becomes green on exposure to sunlight. The yield is about 50 per cent. 

The properties Of phosphorus triiodide.—The deep red tabular or columnar crystals were found by A. E. Nordenskjold to belong to the hexagonal system and to have the axial ratio a 6=1 1T009. The analyses by B. Corenwinder, and... 

Fig. 14 Stereo representation of the columnar crystal packing of [Fe6Cl6(L15)6] (39b), highlighting the compartments with encapsulated disordered chloroform...

Hydroxylamine hydrochloride forms monoclinic columnar crystals, which slowly decompose when exposed to air and water. It has a melting point of 151 Celsius, and is very soluble in water. Hydroxylamine hydrochloride is slightly soluble in methanol, but soluble in glycerol, and propylene glycol. Keep bottles well closed. Hydroxylamine hydrochloride is prepared by treating hydroxylamine with hydrochloric acid (hydroxylamine is prepared by dissolving metallic sodium into liquid ammonia, and then evaporating the excess liquid to obtain dry solid). Hydroxylamine hydrochloride is commercially available. 

In concentrated aqueous solution ammonium bromide is converted by electrolysis or the action of bromine into ammonium tribromide, NH4Br,Br2,.16 This substance is unstable, and forms large columnar crystals with a colour similar to that of potassium dichromate. Ammonium bromide combines with ammonia to form complex de-... 

The most important of the double salts of phosphoric acid with ammonium and the alkali-metals is sodium ammonium hydrogen phosphate or microcosmic salt, NaNH4HP04,4H20, a constituent of putrefying urine, and also present in guano under the name stercorite.17 It can be prepared by the interaction of secondary sodium phosphate and ammonium chloride, or that of secondary ammonium phosphate and sodium chloride. It forms colourless columnar crystals belonging... 

Sodium aurichloride, NaAuCl4,2H20, forms rhombic columnar crystals or lamina .13 Its water of crystallization cannot be expelled without decomposing the salt, a distinction from the potassium derivative. Its solubility in ether is another characteristic point of difference.14 It can be employed as a test for iodides in presence of bromides, the liberated iodine imparting a violet colour to chloroform.15... 

Figure 6 Advances in turbine airfoil technology from polycrystal to columnar crystal to single-crystal castings. (Ref. 28. Reproduced by permission of McGraw-Hill) ...

In thin section, mammillary calcite resembles the palisade calcite of Folk and Assereto (1976), with very large (up to 23 mm long and 2 mm wide), columnar (Logan and Semeniuk, 1976) crystals oriented mostly normal to the surfaces it coats. Each columnar crystal is... 

Rapid accumulation of silt and clay on mammillary surfaces stops crystal growth. Large numbers of very small, equant to columnar crystals that grade quickly to a few large columnar crystals (Fig. 6) mark the reinitiation of crystal growth. 

Mammillary calcite is very dense, with porosities much less than 1%. Pore spaces are of two different types. The first type consists of irregularly shaped pore spaces with fluid inclusions that are commonly oriented parallel with the crystallite boundaries. In traditional speleothems, spindle-shaped inclusions mark the sites where columnar crystals have coalesced (Kendall and Broughton, 1978). In mammillary calcite, the irregular inclusions probably mark... 

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