Big Chemical Encyclopedia

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

Articles Figures Tables About

Strengthening ceramics

We saw in section 7.2.1 that a crack can be deflected by adding particles that the crack cannot penetrate. One example for a ceramic strengthened this way is sintered silicon nitride (SSN, Si3N4) which contains elongated, rod-shaped crystallites with a large aspect ratio. Due to the sintering process, they are... [Pg.249]

Aesthetic dental ceramics are essentially glass-matrix materials with varying volume fractions of crystalline fillers. Crystalline fillers are used in the glass matrix both for dispersion strengthening, usually at volume fractions of 40—70%, and for altering optical properties, usually at low volume fractions. Dental ceramics are generally manufactured from two distinct classes of materials, ie, beneficiated feldspathic minerals and glass—ceramics. [Pg.471]

Ton-exchange approaches and thermal tempering have been evaluated for strengthening dental ceramics (18,19). Both of these approaches are aimed at placing external surfaces of dental ceramic restoration in compression. Only ion exchange is promoted commercially and is not in extensive use. [Pg.472]

If an impurity (copper, say) is dissolved in a metal or ceramic (aluminium, for instance) at a high temperature, and the alloy is cooled to room temperature, the impurity may precipitate as small particles, much as sugar will crystallise from a saturated solution when it is cooled. An alloy of A1 containing 4% Cu ( Duralumin ), treated in this way, gives very small, closely spaced precipitates of the hard compound CUAI2. Most steels are strengthened by precipitates of carbides, obtained in this way. ... [Pg.105]

The result is work-hardening the steeply rising stress-strain curve after yield, shown in Chapter 8. All metals and ceramics work-harden. It can be a nuisance if you want to roll thin sheet, work-hardening quickly raises the yield strength so much that you have to stop and anneal the metal (heat it up to remove the accumulated dislocations) before you can go on. But it is also useful it is a potent strengthening method, which can be added to the other methods to produce strong materials. [Pg.107]

Vitreous ceramics are made waterproof and strengthened by glazing. A slurry of powdered glass is applied to the surface by spraying or dipping, and the part is refired at a lower temperature (typically 800°C). The glass melts, flows over the surface, and is drawn by capillary action into pores and microcracks, sealing them. [Pg.202]

Another means of strengthening ceramics is to create a composite material. Flakes of very strong, tough materials such as titanium diboride, TiB2, are distributed throughout the ceramic material. Even if a crack did form, it would be unable to propagate past the first flake that it encountered. [Pg.737]

E. V. Clougherty, D. Kalish, in Strengthening Mechanisms. Metals and Ceramics, Syracuse Univ. Press, Syracuse, 1966, p. 431. [Pg.312]

Soluble polysilane polymers can also be used as precursors to silicon carbide. The first such application, using (PhMeSi)n-(Me2Si)m copolymers ("Polysilastyrene"), was to strengthen silicon nitride ceramics. The Si3N4 ceramic body was soaked in polysilane and refired, leading to the formation of silicon carbide whiskers in the pore spaces and a consequent increase in strength. (U)... [Pg.16]

Brittle materials, strengthening, 26 775 Brittle particles, ceramic-matrix composite reinforcement, 5 569—570 Brix hydrometer, 23 474 BRL-32872, novel antiarrhythmic agent, 5 106... [Pg.118]

Oxidative damage, role of ascorbic acid in preventing, 25 769 Oxidative degradation, 70 682 of gasoline, 72 399-400 Oxidative dehydrogenation, 23 342-343 Oxidative pyrolysis, 27 466 Oxidative stability, of olefin fibers, 77 229 Oxidative stability test, 72 400 Oxide crystal glass-ceramics, 72 641 Oxide-dispersion-strengthened alloys, 77 103-104... [Pg.661]

Roth, Reidinger and La Placa, 1976). The excess NajO strengthens the ceramic, and practical ceramic membranes contain a mixture of the j3 and P" phases. [Pg.68]

Webb, W. W., H. D. Bartha, and T. B. Shaffer (1966). Strength eharacteristics of whisker crystals, macrocrystals and microcrystals, pp. 329-354. In Strengthening Mechanisms, Metals and Ceramics. Burke, J. J., N. L. Reed, and V. Weiss, Eds. Syracuse University Press, New York. [Pg.18]


See other pages where Strengthening ceramics is mentioned: [Pg.400]    [Pg.707]    [Pg.1555]    [Pg.248]    [Pg.400]    [Pg.707]    [Pg.1555]    [Pg.248]    [Pg.289]    [Pg.320]    [Pg.325]    [Pg.130]    [Pg.190]    [Pg.7]    [Pg.228]    [Pg.199]    [Pg.212]    [Pg.326]    [Pg.400]    [Pg.471]    [Pg.471]    [Pg.472]    [Pg.472]    [Pg.212]    [Pg.202]    [Pg.203]    [Pg.44]    [Pg.737]    [Pg.16]    [Pg.194]    [Pg.427]    [Pg.219]    [Pg.401]    [Pg.761]    [Pg.182]    [Pg.441]    [Pg.289]    [Pg.320]    [Pg.325]    [Pg.80]    [Pg.1678]   
See also in sourсe #XX -- [ Pg.398 ]




SEARCH



Strengthen

Strengthening

© 2024 chempedia.info