Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Manufacturing alumina-based ceramics

Considerable development has occurred on sintered ceramics as bone substitutes. Sintered ceramics, such as alumina-based ones, are uru eactive materials as compared to CBPCs. CBPCs, because they are chemically synthesized, should perform much better as biomaterials. Sintered ceramics are fabricated by heat treatment, which makes it difficult to manipulate their microstructure, size, and shape as compared to CBPCs. Sintered ceramics may be implanted in place but cannot be used as an adhesive that will set in situ and form a joint, or as a material to fill cavities of complicated shapes. CBPCs, on the other hand, are formed out of a paste by chemical reaction and thus have distinct advantages, such as easy delivery of the CBPC paste that fills cavities. Because CBPCs expand during hardening, albeit slightly, they take the shape of those cavities. Furthermore, some CBPCs may be resorbed by the body, due to their high solubility in the biological environment, which can be useful in some applications. CBPCs are more easily manufactured and have a relatively low cost compared to sintered ceramics such as alumina and zirconia. Of the dental cements reviewed in Chapter 2 and Ref. [1], plaster of paris and zinc phosphate... [Pg.245]

Use Glass, ceramics, iron-free aluminum and aluminum salts, manufacture of activated alumina, base for organic lakes, flame retardants, mattress batting. Finely divided form (0.1-0.6 microns) used for rubber reinforcing agent, paper coating, filler, cosmetics. [Pg.44]

Table 4.1 further shows essential mechanical properties of several products of CeramTec s BIOLOX family of alumina-based materials for femoral heads of hip endoprostheses as well as those of BIONIT manufactured by Mathys Orthopadie GmbH (Bettlach, Switzerland). It is evident that decreasing the grain size of the ceramic precursor powders increases both the flexural strength and the fracture toughness of the material dramatically. [Pg.70]

Oxide fibers include glass fibers, mullite fibers, zirconia fibers and alumina fibers. Of these, a-alumina-based fibers have been used intensively for ceramic matrix composites. Fiber FP, manufactured by Du Pont in 1979, was the first wholly a-alumina fiber produced [34]. At present, Almax (Mitsui Mining Material Co. Ltd., Japan) and Nextel 610 (3M Co., USA) are commercially available a-alumina fibers. Almax contains 99.5% alumina and has an elastic modulus of 330 GPa, and Nextel 610 has a tensile strength of 2.4 GPa and an elastic modulus of 380 GPa [35]. [Pg.426]

In forsterite ceramics the mineral forsterite (Mg2Si04) crystallizes. They have excellent low-dielectric-loss characteristics but a high thermal expansion coefficient which imparts poor thermal shock resistance. During the 1960s they were manufactured for parts of rather specialized high-power devices constructed from titanium and forsterite and for which the operating temperature precluded the use of a glass-metal construction. The close match between the thermal expansion coefficients of titanium and forsterite made this possible. Today alumina-metal constructions have completely replaced those based on titanium-forsterite and the ceramic is now manufactured only to meet the occasional special request. [Pg.276]

The MF membranes are usually made from natural or synthetic polymers such as cellulose acetate (CA), polyvinylidene difiuoride, polyamides, polysulfone, polycarbonate, polypropylene, and polytetrafiuoroethylene (FIFE) (13). Some of the newer MF membranes are ceramic membranes based on alumina, membranes formed during the anodizing of aluminium, and carbon membrane. Glass is being used as a membrane material. Zirconium oxide can also be deposited onto a porous carbon tube. Sintered metal membranes are fabricated from stainless steel, silver, gold, platinum, and nickel, in disks and tubes. The properties of membrane materials are directly reflected in their end applications. Some criteria for their selection are mechanical strength, temperature resistance, chemical compatibility, hydrophobility, hydrophilicity, permeability, permselectivity and the cost of membrane material as well as manufacturing process. [Pg.207]

Afterburning processes enable the removal of pollutants such as hydrocarbons and volatile organic compounds (VOCs) by treatment under thermal or catalytical conditions. Combinations of both techniques are also known. VOCs are emissions from various sources (e.g. solvents, reaction products etc. from the paint industry, enaml-ing operations, plywood manufacture, printing industry). They are mostly oxidized catalytically in the presence of Pt, Pd, Fe, Mn, Cu or Cr catalysts. The temperatures in catalytic afterburning processes are much lower than for thermal processes, so avoiding higher NOx levels. The catalysts involved are ceramic or metal honeycombs with washcoats based on cordierite, mullite or perovskites such as LaCoOs or Sr-doped LaCoOs. Conventional catalysts contain Ba-stabilized alumina plus Pt or Pd. [Pg.322]

The aforementioned fibers are combined with various matrix materials to produce oxide-oxide CMCs. Coatingless, porous-matrix CMCs based on fabric reinforcement are the most fully developed and examples of these materials are given in Table 2. General Electric s (GE) GEN-IV was one of the earliest porous matrix, all-oxide fiber composites, while COI Ceramics (COI ) is currently the most prominent commercial supplier of oxide-oxide composites. The matrix materials are primarily aluminosilicate (ex. manufacturers GE, COI), alumina-mullite (University of California, Santa Barbara [UCSB]), and/or alumina (COI). [Pg.387]

Filters for Molten Metal Inclusions in molten metals, such as oxide skins, mold sand particles, inoculation reaction byproducts or furnace slags, can be efficiently removed by filtering through pressed cellular, extruded cellular, or foam ceramic filters manufactured from high-temperature-resistant, chemically inert alumina, and also mullite, silicon carbide, and stabilized zirconia. Alumina is particularly useful when filtering liquid aluminum alloys in the range of 750-850 °C, and copper-based alloys at 1000-1200°C (Matthews, 1996). These ceramic filters are designed for use in either batch or in-mold filtration ... [Pg.188]


See other pages where Manufacturing alumina-based ceramics is mentioned: [Pg.209]    [Pg.40]    [Pg.1393]    [Pg.172]    [Pg.118]    [Pg.212]    [Pg.123]    [Pg.172]    [Pg.285]    [Pg.118]    [Pg.212]    [Pg.180]    [Pg.78]    [Pg.1393]    [Pg.267]    [Pg.248]    [Pg.214]    [Pg.753]    [Pg.3]    [Pg.214]    [Pg.470]    [Pg.6]    [Pg.382]    [Pg.349]    [Pg.1078]    [Pg.421]    [Pg.421]    [Pg.423]    [Pg.221]    [Pg.676]    [Pg.635]    [Pg.648]    [Pg.222]    [Pg.78]    [Pg.213]    [Pg.676]    [Pg.1391]    [Pg.1393]    [Pg.2]    [Pg.207]    [Pg.32]    [Pg.311]   
See also in sourсe #XX -- [ Pg.650 ]




SEARCH



Alumina manufacture

Alumina-based ceramics

Bases Alumina

Ceramic manufacturing

Ceramics manufacture

Manufacturing ceramics manufacture

© 2024 chempedia.info