Aluminum and alumina

Engelbrecht FM, Byers PD, Stacy BD, et al. 1959. Tissue reactions to injected aluminum and alumina in the lungs and livers of mice, rats, guinea-pigs and rabbits. J Pathol Bacteriol 77 407-416. 

Hunter D, Milton R, Perry KMA, et al. 1944. Effects of aluminum and alumina on the lung in grinders of duralumin aeroplane propellers. Br J Ind Med 1 159-164. 

Brukin, A.R. (1987) Production of Aluminum and Alumina, Critical Reports in Applied Chemistry, Vol. 20, John Wiley Sons, Ltd., Chichester. 

While catalyst activity is generally inversely related to the amount of aluminum and alumina present it is not desirable to remove all of these materials from the nickel. It has been proposed that some aluminum in the nickel crystal lattice creates the defect sites responsible for catalytic activity. The alumina appears to prevent the sintering of the nickel particles. With the 20% alumina that is found in the commercial catalyst, heating to 500°C results in only a 20% reduction in surface area. When only 1% alumina is present there is a 50% reduction in surface area at this temperature but no change in surface area on heating to 250°C. 

Apparatus. The experimental unit, shown in Figure 1, was made of stainless steel and was used for the simultaneous operation of up to seven Alonized (a process which coats the stainless steel with aluminum and alumina it renders the reactor walls inert for Fischer-Tropsch reactions and, more importantly, for interaction by sulfur compounds) stainless steel reactors, all at the same temperature, pressure, H2.-CO ratio, and space velocity. The unit could be used at pressures up to 3 MPa. 

Vaidya, R. U., Butt, D. P., Hersman, L. E., and Zurek, A. K., "Effect of Microbiologically Influenced Corrosion on the Tensile Stress-Strain Response of Aluminum and Alumina-Particle Reinforced Aluminum Composite, Corrosion, Vol. 53, No. 2, 1997, pp. 136-141. 

Coudurier L, Adorian J, Pique D, Eustathopoulos N. Study of the wettability by liquid aluminum and alumina covered with a layer of a refractory compound. Rev Int Haute Temp. 

The method of obtaining aluminum metal by the electrolysis of alumina dissolved in cryolite was discovered in 1886 by Hall in the U.S. and at about the same time by Heroult in France. Cryolite, a natural ore found in Greenland, is no longer widely used in commercial production, but has been replaced by an artificial mixture of sodium, aluminum, and calcium fluorides. 

Traditional adsorbents such as sihca [7631 -86-9] Si02 activated alumina [1318-23-6] AI2O2 and activated carbon [7440-44-0], C, exhibit large surface areas and micropore volumes. The surface chemical properties of these adsorbents make them potentially useful for separations by molecular class. However, the micropore size distribution is fairly broad for these materials (45). This characteristic makes them unsuitable for use in separations in which steric hindrance can potentially be exploited (see Aluminum compounds, aluminum oxide (ALUMINA) Silicon compounds, synthetic inorganic silicates). 

There are several processes available for the manufacture of cryoHte. The choice is mainly dictated by the cost and quaUty of the available sources of soda, alumina, and fluoriae. Starting materials iaclude sodium aluminate from Bayer s alumina process hydrogen fluoride from kiln gases or aqueous hydrofluoric acid sodium fluoride ammonium bifluoride, fluorosiUcic acid, fluoroboric acid, sodium fluosiUcate, and aluminum fluorosiUcate aluminum oxide, aluminum sulfate, aluminum chloride, alumina hydrate and sodium hydroxide, sodium carbonate, sodium chloride, and sodium aluminate. 

The magnesia and alumina suspension is prepared by treatment of an aqueous solution, containing aluminum and magnesium salt in the desired proportion, with sodium hydroxide. The coprecipitated aluminum and magnesium hydroxides are collected by filtration, washed free of soluble salts, and stabilized by the addition of a suitable hexatol. 

An important appHcation of MMCs in the automotive area is in diesel piston crowns (53). This appHcation involves incorporation of short fibers of alumina or alumina—siHca in the crown of the piston. The conventional diesel engine piston has an Al—Si casting alloy with a crown made of a nickel cast iron. The replacement of the nickel cast iron by aluminum matrix composite results in a lighter, more abrasion resistant, and cheaper product. Another appHcation in the automotive sector involves the use of carbon fiber and alumina particles in an aluminum matrix for use as cylinder liners in the Prelude model of Honda Motor Co. 

In 1976 the first section of a new smelting process that requited 30% less electric power than the best Hah-HAroult cehs came on stream. In this process, alumina, carbon, and chlorine reacted to produce aluminum chloride and carbon dioxide. The aluminum chloride was electrolyzed in bipolar electrode cehs to produce aluminum and chlorine and the chlorine was recycled to make more aluminum chloride. After six years of operation, the plant... 

Aluminum halides and aluminumnitrate, Aluminum oxide(Alumina),... 

Anhydrous aluminum chloride, AIQ, is manufactured primarily by reaction of chlorine [7782-50-5] vapor with molten aluminum and used mainly as a catalyst in organic chemistry ie, in Friedel-Crafts reactions (qv) and in proprietary steps in the production of titanium dioxine [13463-67-7] Ti02, pigment. Its manufacture by carbochlorination of alumina or clay is less energy-intensive and is the preferred route for a few producers (19). 

Gibbsite is aii important technical product and world production, predominantly by the Bayer process, is more than 50 million metric tons aimuaHy. Alost (90%) is calcined to alumina [1344-28-1 j, Al202, to be used for aluminum production. Tlie remainder is used by the chemical industry as filler for paper, plastics, rubber, and as the starting material for the preparation of various aluminum compounds, alumina ceramics, refractories, polishing products, catalysts, and catalyst supports. 

Pulpstones. Improvements have been made in the composition and speed of the grinding wheel, in methods of feeding the wood and pressing it against the stone, in control of power to the stones, and in the size and capacity of the units. The first pulpstones were manufactured from quarried sandstone, but have been replaced by carbide and alumina embedded in a softer ceramic matrix, in which the harder grit particles project from the surface of the wheel (see Abrasives). The abrasive segments ate made up of three basic manufactured abrasive siUcon carbide, aluminum oxide, or a modified aluminum oxide. Synthetic stones have the mechanical strength to operate at peripheral surface speeds of about 1200—1400 m /min (3900 to 4600 ft/min) under conditions that consume 0.37—3.7 MJ/s (500—5000 hp) pet stone. 

Calcium—Silicon. Calcium—silicon and calcium—barium—siUcon are made in the submerged-arc electric furnace by carbon reduction of lime, sihca rock, and barites. Commercial calcium—silicon contains 28—32% calcium, 60—65% siUcon, and 3% iron (max). Barium-bearing alloys contains 16—20% calcium, 9—12% barium, and 53—59% sihcon. Calcium can also be added as an ahoy containing 10—13% calcium, 14—18% barium, 19—21% aluminum, and 38—40% shicon These ahoys are used to deoxidize and degasify steel. They produce complex calcium shicate inclusions that are minimally harm fill to physical properties and prevent the formation of alumina-type inclusions, a principal source of fatigue failure in highly stressed ahoy steels. As a sulfide former, they promote random distribution of sulfides, thereby minimizing chain-type inclusions. In cast iron, they are used as an inoculant. 

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