Ceramics chemically bonded

Key words Titanium aluminum carbide TiB2t composite ceramic chemical bond property INTRODUCTION... 

Bioglasses are surface-active ceramics that can induce a direct chemical bond between an implant and the surrounding tissue. One example is 45S5 bioglass, which consists of 45% Si02, 6% 4.5% CaO, and 24.5% Na20. The various calcium phosphates have exceUent compatibUity with bone and... 

Curing. Some chemically bonded bricks requke some elevated heat treatment that is typically higher than the tempering process mentioned above, but less temperature than that requked to form ceramic bonds. One example is aluminosihcate brick bonded with phosphoric acid. A very strong... 

Fig. 2.40. Chemical-bond analysis of an additional phase in a BaTiOs ceramic using differences in the O-K ELNES.

As with advanced ceramics, chemical reactions play a cracial role in the fabrication of ceramic composites. Both defect-free ceramic fibers and optimal chemical bonds between fiber... 

Immobilization by chemical bonding gives strong, irreversible attachments to a solid support. The bonds are normally covalent but they can be electrostatic. Typical supports are functionalized glass and ceramic beads and fibers. Enzymes are sometimes cross-linked to form a gel. Occasionally, enz5anes can be flocculated while retaining catalytic activity. 

The technique is referred to by several acronyms including LAMMA (Laser Microprobe Mass Analysis), LIMA (Laser Ionisation Mass Analysis), and LIMS (Laser Ionisation Mass Spectrometry). It provides a sensitive elemental and/or molecular detection capability which can be used for materials such as semiconductor devices, integrated optical components, alloys, ceramic composites as well as biological materials. The unique microanalytical capabilities that the technique provides in comparison with SIMS, AES and EPMA are that it provides a rapid, sensitive, elemental survey microanalysis, that it is able to analyse electrically insulating materials and that it has the potential for providing molecular or chemical bonding information from the analytical volume. 

Hench, L.L. and Paschall H.A. (1973) Direct chemical bond of bioactive glass-ceramic materials to bone and muscle. Journal of Biomedical Materials Research Symposium, 4, 25. 

Chemically bonded hybrid material which is a crosslinked organic-inorganic polymer. Note Ceramers are usually prepared by sol-gel processing of oligomers or polymers with reactive silyloxy substituents. 

Ceramicrete is an ex situ stabilization technology that uses chemically bonded phosphate ceramics to stabilize low-level radioactive waste and hazardous waste containing radionuclides and heavy metals. The technology mixes phosphates with acidic solution, causing an exothermic reaction similar to that used in forming concrete. But while concrete is based on relatively weak hydrogen and van der Waals bonding, Ceramicrete uses a combination of ionic, covalenf and van der Waals bonds to stabilize contaminants. 

See Lead zirconate titanate ceramics Quality number 219 Quantum transmission 59 Reciprocal space 123, 353 Reciprocity principle 88 Reconstruction 14, 327 Au(lll) 327 DAS model 16 Si(lll)-2X1 14 Recursion relations 352 Repulsive atomic force 185, 192 Resonance frequency 234, 241 piezoelectric scanners 234 vibration isolation system 241 Resonance interactions 171, 177 and tunneling 177 Resonance theory of the chemical bond 172... 

Low-temperature treatment of low-level mixed wastes has also been accomplished by solidification/stabilization with chemically bonded phosphate ceramics (CBPC). These are made by hydrothermal chemical reaction rather than by sintering. Chemical bonding develops when acid phosphates react with oxides to form crystalline orthophosphate (Singh et al. 1997). The ceramic matrix stabilizes the wastes by microencapsulation. The low temperature of the reaction allows volatile radionuclides to be treated (Singh et al. 1997). 

Singh, D., Wagh, A. S., Cunnane, J. C. Mayberry, J. L. 1997. Chemically bonded phosphate ceramics for low-level mixed-waste stabilization. Journal of Environmental Science and Health, Part A Environmental Science and Engineering Toxic and Hazardous Substance Control, A32, 527-541. 

Wagh, A. S., Strain, R., Jeong, S. Y., Reed, D., Krause, T. Singh, D. 1999. Stabilization of Rocky Flats Pu-contaminated ash within chemically bonded phosphate ceramics. Journal of Nuclear Materials, 265, 295-307. 

CASH CBM CBO CBPC CC CCB CCM CCP CDB CEC CFBC CFC CFR CMM COP CSH CT Calcium aluminosilicate hydrate Coal bed methane Carbon burn-out Chemically-bonded phosphate ceramics Carbonate carbon Coal combustion byproducts Constant capacitance model Coal combustion product Citrate-dithionate-bicarbonate Cation exchange capacity Circulating fluidized bed combustion Chlorofluorocarbon Cumulative fraction Coal mine methane Coefficient of performance Calcium silicate hydrate Collision theory... 

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