Alumina powder

Characteristics ofMlumina Powders, Alumina Ceramic Manufacturers Association, New York, 1976, pp. 1—4. 

Microprobe studies of pack-chromised iron (Cr powder, alumina, CrCl, mixture) shows that the surface Cr concentration builds up with time to 95% in 20 h at 1 300 K ", and that the diffusion coefficient for Cr in a-phase is very concentration dependent. The growth of carbides during pack-chromising and during gas-vanadising have been studied. 

Notably, the nature of the support, that is powder or thin film, appears to have some influence on the course of the reaction. Indeed, on flat substrates Tysoe and coworkers [9, 10] observed the formation of Mo(lV) species and the only loss of CO in the gas phase, in contrast with powdered alumina for which Mo(V) and loss of CO2 + H2 characterize the relevant surface chemistry. 

This discovery was soon followed by the isolation of barium, strontium, and calcium. By analogy, it was further inferred that all amorphous powders—alumina, magnesia, etc.—possessing similar properties, were metallic oxides. As a result, when a new earth is now discovered, chemists believe, by faith, that it is the oxide of a metal even in cases where the supposed metal has never been isolated. 

Acrylic resins, activated carbon, adipic acid, alfalfa, alga powder, alumina, aluminium, ammonium chloride, animal feed, anthracite, asbestos... 

Dehydration of powdered alumina at 250°-750°C followed by reaction with Nb(7r-allyl)4 gave, in all cases, spectra identical to Figure 13. 

The general usage of the terms lyophilic and lyophobic in describing colloidal systems is somewhat illogical. Lyophobic traditionally describes liquid dispersions of solid or liquid particles produced by mechanical or chemical action however, in these so-called lyophobic sols (e.g. dispersions of powdered alumina or silica in water) there is often a high affinity between the particles and the dispersion medium - i.e. the particles are really lyophilic. Indeed, if the term lyophobic is taken to imply no affinity between particles and dispersion medium (an unreal situation), then the particles would not be wetted and no dispersion could, in fact, be formed. Lyophilic ... 

Wilson et al. [25] analyzed various brands of commercial cements and specified their possible composition, properties, and microstructure. Wilson et al. report the most representative and comprehensive data on commercial porcelain dental cements. These cements consist of powdered alumina-lime-silica glass mixed with phosphoric acid that formed a hard and translucent product. The starter glass powder consists of 31.5-41.6 wt% silica, 27.2-29.1 wt% alumina, 7.7-9.0wt% calcium oxide, 7.7-11.2 wt% sodium oxide, 13.3-22 wt% fluorine and small amounts of phosphorous and zinc oxides. Often very small amounts of magnesium and strontium oxides are also present. 

An alternative process based on two sequential catalytic cracking stages aimed at obtaining gasoline and diesel from waste plastics or heavy oil/waste plastics mixtures is shown in Figure 3.16 [99]. The catalyst employed in the first step is made up of powder alumina, waterglass and HZSM-5 zeolite and is mixed up directly with the waste plastics in a screw reactor preferably at 600-700°C. The second catalytic step consists in a fixed... 

Y.-H. Seo et al. [5] HDPE The reactor was a 1.1 L round stainless steel bottle placed in a furnace 5 ZSM-5 (powder) Y-zeohte (powder) Y-zeohte (pellet) Mordenite (pellet) Silica-alumina (powder) Alumina (powder)... 

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. 

Berrylium, Precious Metals, Aluminum, Silicon, Nickel Glass Rawmix, Furnace Dust, Glass Powder Alumina, Catalyst, Molecular Sieves, Substrates, Insulator Body, Tilemix, Press Feed, Proppants, Frits, Colors Bauxite, Alumina, Kiln Dust, Blends Raw Meal, Kiln Dust... 

Material Fine/medium powder Fly ash, pulverized coal, plastic powders, alumina, granular sugar, pharma excipients Course powder Sand, salt, granules, mineral powders, glass beads Cohesive fine powder Cement, corn starch, tit anium dioxide, carbon-black powder, many pharma actives Granular Plastic pellets, wheat, large glass beads, tablets, course sand, seeds... 

To correct the anode effect, fresh powdered alumina prewarmed on the electrolyte crust of the cell is broken into the molten electrolyte with a remotely controlled pneumatic hammer. The anode polarizing gas was once dispelled by the rapid flow of combustion gases from the burning of a green wood pole poked through the crust. Now, however, air lances are used to accomplish this task, referred to as poling. ... 

Most commercial catalysts are used in the form of either spheres or cylindrical pellets of 1-6 mm diameter, with the cylinders typically having a length to diameter ratio <3. There are three main methods that are used to form such shaped pellets from the irregularly shaped catalyst particles obtained via precipitation or from the powdered alumina, silica, etc. used in making the support for an impregnated catalyst. ... 

Column electrophoresis is carried out in an apparatus such as that shown in Figure 4. Glass powder, alumina, splinters, or quartz powder is used as a support. The support is first impregnated with the ionic liquid, then a solution of the sample is applied at the center of the separation column and the electric field applied. Column electrophoresis is commonly used for isotope separations. 

Alumina trihydrate (aluminum hydroxide, aluminum hydrate, and hydrated aluminum oxide) n. Al203 3H20 for Al(OH)3. A white crystalline powder, alumina trihydrate accounts for about half of all flame retardants used in plastics. When heated above about 220° C, it releases water endothermically. 

Bedder. A plaster shape conforming to that of the ware to be fired and used to form the bed of powdered alumina on which bone china is fired. 

Long ago, the refractory layer was made from powdered alumina that was poured on a layer of heat irtsrrlatiort. After shutdown of the cell, the alumina, infiltrated by electrolyte, was used for the production of alumina. The main disadvantages of such a variant are high thermal conductivity and low resistance to electrolyte. This type of refractory lining is not used today. 

There is a belief that the question on the optimal silica/alumina ratio in fireclay brick for reduction cells will not be resolved with a strict proportion. Indirect evidence for this belief are numerous industrial trials of using silica bricks, powdered silica sand, all variants of fireclay brick, powdered fireclay, mullite bricks, alumina bricks, powdered alumina, and red constructional bricks as a refractory barrier layer. 

There is a long history of trials with different barrier materials silica block, silica powder, alumina brick, alumina powder, red constructional brick, mullite brick, various combinations of muUite brick of fireclay brick in the upper and lower layers. 

A catalyst is required for this reaction. Requirements are high activity, long life, good physical strength, and low cost. Such a catalyst can be prepared by mixing nickel oxide powder, alumina, and calcium aluminate... 

In a typical experiment, a sample of powdered alumina (Rhone Poulenc CISC 5g, particles average diameter 0.1 mm) is dried under vacuum at room temperature during 7 hours. It is then transferred, under an Ar atmosphere in the reaction flask and 120 ml of dry benzene are added. 2.5 ml of AlEt ... 

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