Aluminum oxide alumina glasses

See Aluminum COMPOUNDS, aluminum oxide (alumina) Asbestos Glass Refractory fibers Silica. 

Oxide Aluminum oxide, alumina AI1O3, white solid, insoluble, melting point 2020 C. formed by heating aluminum hydroxide to decomposition when bauxite is fused in the electric furnace and then cooled, there results a very hard glass ( alundum ), used as an abrasive (hardness 9 Mohs scale) and heat refractory material. Aluminum oxide is the only oxide that reacts both 111 H20 medium and at fusion temperature, 10 form salts with both acids and alkalis. 

Add a small piece of glass wool and with the aid of a glass rod push it down near the stopcock. Add 15-16 mL of petroleum ether to the buret. Open the stopcock slowly and allow the solvent to fill the tip of the buret. Close the stopcock. You should have 12-13 mL of solvent above the glass wool. Weigh 20 g of aluminum oxide (alumina) in a 100-mL beaker. Place a small funnel on top of your buret. Pour the alumina into the buret. Allow the alumina to settle in order to form a 20-cm column. Drain the solvent but do not allow the column to run dry. Always have at least 0.5 mL of clear solvent above the alumina in the column. If alumina adheres to the walls of the buret, wash it down with more solvent. 

Aluminum oxide [BioRad Alumina (oxide), AG-7] is suspended in chloroform-methanol (1 1, v/v) and then transferred to a glass chromatography tube fitted with a Teflon stopcock. Solvent is allowed to flow through until... 

Fillers used in large quantities to reinforce plastics are alumina (aluminum oxide), calcium carbonate, calcium silicate, cellulose flock, cotton (different forms), short glass fiber, glass beads, glass spheres, graphite, iron oxide powder, mica, quartz, sisal, silicon carbide, dtanium oxide, and tungsten carbide. Choice of filler varies and depends to a great extent upon the requirements of the end item and method of fabrication. 

Porcelain dental cements were developed by Steenbock [6] who produced silico-phosphate dental material using 50 wt% concentrated phosphoric acid solution and an aluminosilicate glass. Wilson et al. [7] showed that various brands of commercial cements consist of powdered alumina-lime-silica glass mixed with phosphoric acid, which form a hard and translucent product. The phosphoric acid used in these cements is partially neutralized by aluminum oxide. 

The combustion chamber was a round channel 9.53 mm in diameter and 0.864 m long. The first 0.623 m was confined by a high purity, aluminum oxide tube. The final 0.241 m consisted of the central hole of an aluminum oxide block formed from WulflE furnace elements. The tube was insulated with 6.4 mm of powdered alumina surrounded by a larger aluminum oxide tube which was in turn insulated with glass fibers. Propane-air flames in six equidistant surroimding channels acted as guard heaters in the block. The block was insulated with powdered alumina. 

Aluminium fluoride Aluminium fluorure Aluminum fluoride (AIF3) Aluminum trifluoride CCRIS 2282 EINECS 232-051-1 Fluorid hlinity HSDB 600. Used mixed with aluminum oxide and silica for use as an electrolyte in reduction of alumina to aluminum metal as flux in remelting and refining of aluminum and its alloys opacifier aid In production of ceramic enamels, glass, and glazes. Crystals sublimes 1272 soluble in H20 (0.559 g/100 ml). Alcan Chem. 

Garino-Canina and Cohen (125) usedTL curves to characterize germanium oxide-aluminum oxide mixtures. It was found that after excitation by ultraviolet radiation, the peak positions, between 50 and 70°C, and the peak intensities of the curves varied with a change in alumina content introduced into the germanium oxide glass. The amount of alumina varied from 0 to 5%. 

As heated alkalies readily attack stainless steel, it was found necessary to use liners or crucibles in the above bombs. Borosilicate glass was found satisfactory up to about 450 °C. for short periods of time, but it could not be used above this temperature. Various ceramic materials were tried for possible use as containers for the sodium peroxide-superoxide mixtures. Sintered aluminum oxide and magnesium oxide were satisfactory up to 450 °C., but above this temperature the sodium oxides penetrated the sintered material and corroded the stainless steel bomb. Commercial ceramic coatings containing (as the principal components) alumina, magnesia, and titania were also tried without success at a temperature above 450 C. 

It is generally assumed that most, if not all, of the aluminum in these glasses will occur in aluminum-oxygen tetrahedra, so long as the total concentration of alkali and/or alkaline earth oxides equals or exceeds that of alumina. These tetrahedra substitute directly into the network for silicon-oxygen tetrahedra. It follows that alumina, which does not readily form a glass by itself, can, however, easily replace silica in the vitreous network. Oxides which act in this manner are said to be intermediate in behavior between glass formers and modifier oxides. 

If the glass contains lead and/or barium oxide, the glass should be treated with a mixture of hydrofluoric and sulfuric acids and the insoluble lead and barium sulfates filtered off before the titration. Lead may also be precipitated with hydrogen sulfide. Small amounts of aluminum and iron may be masked with triethanolamine. Greater amounts of aluminum and iron must be preseparated by precipitation as their hydrated oxides in the procedure for gravimetric determination of alumina. If the content of iron oxide, alumina, and titania is large, they can be separated using a 25% solution of urotropin. 

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