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Composites alumina

The sol—gel technique has been used mosdy to prepare alumina membranes. Figure 18 shows a cross section of a composite alumina membrane made by sHp coating successive sols with different particle sizes onto a porous ceramic support. SiUca or titanium membranes could also be made by the same principles. Unsupported titanium dioxide membranes with pore sizes of 5 nm or less have been made by the sol—gel process (57). [Pg.70]

FIGURE 5.6 This is a fractured sample of a ceramic composite (alumina with 30 volume-percent silicon carbide whiskers). The lighter regions of circular or cylindrical shape are randomly oriented whiskers protruding from the fractured surface. The rod-like depressions in the surface mark places where whiskers nearly parallel with the fracture were pulled out. Courtesy, Roy W. Rice, W. R. Grace and Company. [Pg.82]

Consider the case of determining alkaline and alkaline-earth concentrations. The catalyst samples where the matrix is alumina or a zeolite are reduced to a powder and dissolved in hydrochloric acid solution either by direct attack by high purity acids or after fusion with lithium metaborate. The choice of acids used to attack the samples depends both on their composition (alumina or aluminium silicate) and on the active elements present. Success of the method in forming a solution depends partly on the information available on the composition of the sample. If the presence of certain elements is not known, it may be necessary to test several methods prior to obtaining a satisfactory dissolution. [Pg.53]

Different supports are used, (see Section 10.6.4) with different geometry (discs or tubes), thickness, porosity, tortuosity, composition (alumina, stainless steel, silicon carbide, mullite, zirconia, titania, etc.), and symmetry or asymmetry in its stmcture. Tubular supports are preferable compared to flat supports because they are easier to scale-up (implemented as multichannel modules). However, in laboratory-scale synthesis, it is usually found that making good quality zeolite membranes on a tubular support is more difficult than on a porous plate. One obvious reason is the fact that the area is usually smaller in flat supports, which decreases the likelihood of defects. In Figure 10.1, two commercial tubular supports, one made of a-alumina (left side) and the other of stainless steel (right side) used in zeolite membrane synthesis, are shown. Both ends of the a-alumina support are glazed and both ends of the stainless steel support are welded with nonporous stainless steel to assure a correct sealing in the membrane module and prevent gas bypass. [Pg.270]

Glass/alumina composite Alumina Borosilicate glass (Pyrex)... [Pg.52]

On the other hand, since the hardness and the chemical stability are equally important in the field of the prosthesis, these composite materials, with relatively low contents of zirconia (10 % in volume), display values of hardness similar to those of alumina and they are not susceptible to the hydrothermal instability observed in some cases of the stabilised zirconia bioceramics. Therefore, these materials appear like an alternative, to consider in the future, for the production of ceramics prostheses. Figure 1 shows a microstructure of one of these composite alumina-zirconia materials. [Pg.107]

Fillers that contain combined water or carbon dioxide, such as alumina trihydrate, Mg(OH)2, or dawsonite [12011 -76-6] increase fire resistance by hberating noncombustible gases when they are heated. These gases withdraw heat from the plastic and can also reduce the oxygen concentration of the air surrounding the composition. [Pg.370]

Starch is a polysaccharide found in many plant species. Com and potatoes are two common sources of industrial starch. The composition of starch varies somewhat in terms of the amount of branching of the polymer chains (11). Its principal use as a flocculant is in the Bayer process for extracting aluminum from bauxite ore. The digestion of bauxite in sodium hydroxide solution produces a suspension of finely divided iron minerals and siUcates, called red mud, in a highly alkaline Hquor. Starch is used to settle the red mud so that relatively pure alumina can be produced from the clarified Hquor. It has been largely replaced by acryHc acid and acrylamide-based (11,12) polymers, although a number of plants stiH add some starch in addition to synthetic polymers to reduce the level of residual suspended soHds in the Hquor. Starch [9005-25-8] can be modified with various reagents to produce semisynthetic polymers. The principal one of these is cationic starch, which is used as a retention aid in paper production as a component of a dual system (13,14) or a microparticle system (15). [Pg.32]

The quantity of feed materials required are 1—1.05 kg of metallic reductant, 5.4 kg of dolime, and 0.35 kg of calcined bauxite or alumina to produce 1 kg of magnesium. The quantity of slag produced depends on the feed material composition and may vary from 5.2 to 5.9 kg/kg of magnesium. [Pg.321]

Particle or discontinuously reinforced MMCs have become important because they are inexpensive compared to continuous fiber-reinforced composites and they have relatively isotropic properties compared to the fiber-reinforced composites. Figures la and b show typical microstmctures of continuous alumina fiber/Mg and siUcon carbide particle/Al composites, respectively. [Pg.194]

Fig. 1. Typical microstmctures of some metal-matrix composites (a) continuous alumina fiber/Mg and (b) siUcon carbide particle/Al composites. Fig. 1. Typical microstmctures of some metal-matrix composites (a) continuous alumina fiber/Mg and (b) siUcon carbide particle/Al composites.
Table 3. Effect of Fiber Braiding on Fracture Energy of Alumina Fiber/Al—Li Composite ... Table 3. Effect of Fiber Braiding on Fracture Energy of Alumina Fiber/Al—Li Composite ...

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Alumina based composites

Alumina chemical composition

Alumina composite electrodes

Alumina composite material

Alumina composites with monazite

Alumina composites with silicon carbide whiskers

Alumina copper composites

Alumina fiber-glass matrix composite

Alumina matrix composites, fiber reinforced

Alumina reinforced YSZ composites

Alumina reinforced zirconia composites

Alumina whisker-zirconia matrix composite

Alumina zirconia composites

Alumina-filled composites, thermal shock resistance

Alumina-filled epoxy composites

Alumina-filled epoxy composites materials

Alumina-glass dental composites

Alumina/polyimide composite

Black composites, alumina

Glass/alumina composite

High Density Polyethylene (HDDE)-Alumina Composites

High alumina cement composition

High-density polyethylene-alumina composites

Hollow Silica-Alumina Composite

Interfacial debonding alumina composites

Metal-matrix composites alumina effect

Montmorillonite-Alumina Composite

Oxide fiber reinforced alumina matrix composites

Phenolic/MWCNT-alumina composites

Titania alumina composite membranes

Toughness, fracture alumina-filled composites

Whisker reinforced composites alumina

Zirconia-toughened alumina matrix composite

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