High-Tech Ceramics

Specialty Aluminas. Process control (qv) teclmiques permit production of calcined specialty aluminas ha nng controlled median particle sizes differentiated by about 0.5 ]lm. Tliis broad selection enables closer shrinkage control of high tech ceramic parts. Production of pure 99.99% -AI2O2 powder from alkoxide precursors (see Alkoxides, metal), apparently in spherical form, offers the potential of satisfying the most advanced appUcations for calcined aluminas requiring tolerances of 0.1% shrinkage. 

Kingery, W.D. (1990) An unseen revolution the birth of high-tech ceramics, in Ceramics and Civilization, vol. 5 (The American Ceramic Society, Westerville, Ohio) p. 293. Kingery, W.D. and Berg, M. (1955) J. Appl. Phys. 26, 1205. 

Material Quartz and ceramic materials (Barium titanate (BaTiOQ, Lead metaniobate (PbNb2Os) and the mixed crystal Lead-zirconate titanate) Nickel or an alloy of Nickel. Also, some other high-tech alloys with ferrite materials (MFe204, M = divalent metal like Ni, Zn and Pb)... 

The spectrum of silicon based polymers is enriched by high tech ceramics like silicon nitride and carbide, respectively. These materials are produced by pyrolysis of appropriate polymeric precursors such as polysilanes, polycarbosilanes and polysilazanes (preceramics). These synthetic ceramics display a certain analogy to silicates, having SiC, SiN, or Si(C,N) as structural subunits instead ofSiO. 

Schafer W and Schmidberger R. Ca and Sr doped LaCr03 Preparation, properties, and high temperature applications. In Vincenzini P, editor. High Tech Ceramics. Amsterdam, the Netherlands Elsevier Science Publishers, 1987 1737-1742. 

Matijevic E (1987) In Vincenzini P (ed) High tech ceramics, materials science monographs, 38A. Elsevier Science Publishers, Amsterdam, p 441... 

Mostaghaci. H. Ailvamed Ceramic Materials Applicalimis ttf Advanced Material in a High Tech Swirly I. Trans Technical Publishing. Zuerich, Switzerland. 1997 Munz. D. and T. Feel Ceramics Mechanical Pmjterties. Failure Behaviour. 

It is very understandable that people know so little about ceramics. Ever since time immemorial, clay has been an important ceramic raw material. Not until approximately 1850 were other (synthetic) raw materials introduced in ceramics. The objects which are made of the latter often have specific properties which clearly differ from those of the clay ceramics and which meet the requirements of the sophisticated high-tech world of the nineties. So ceramics involve much more than simply clay ceramics and are, in my view, well worth writing a book about. 

The polysilanes can be regarded as one-dimensional analogs to elemental silicon, on which, of course, nearly all of modem electronics is based. The photophysical behavior of polysilanes is not approached by any other materials, save for the less stable and more costly polygermanes and polystannanes. The remarkable properties of polysilanes have led to intense interest, and to numerous proposed high-tech applications. But the great promise of polysilanes as materials has yet to be realized. Their only commercial use at present is as precursors to silicon carbide ceramics, an application which takes no advantage of their optical or electronic properties. 

Photoelectron, Nuclear Gamma-Ray and Infrared Absorption Spectroscopic Studies of Neptunium in Sodium Silicate Glass, B.W. Veal, W.T. Camall, B.D. Dunlap, A.W. Mitchell, and D.J. Lam (Eds.), In High Tech Ceramics, P. Vincenzini (Ed.), Elsevier Science Publisher, Amsterdam, 1987, pp. 2903-2910. 

J. Sjoberg, K. Rundgren, R. Pompe and J. Sjoberg, High tech Ceramics, 1987, 535. 

Ceramic Ceramics are nonmetallic materials that have been created under intense heat. Ceramics tend to be extremely hard, heat-resistant and corrosion-resistant. They are generally poor conductors of temperature changes or electricity. Ceramics are used in low-tech and high-tech applications, ranging from the insulators in spark plugs to the heat shield on the Space Shuttle. 

T. Yamamura, T. Harashima, M. Shibuya, and Y. Iwai, Development of Continuous Si-Ti-C-O Fiber With High Mechanical Strength and Heat Resistance, 6th World Congress on High Tech. Ceramics (CIMTEC), Milan, Italy, 1986. 

Dirksen, J. A., and Ring, T. A., in High-Tech Ceramics, Views and Perspectives (G. Kostors, ed.). Chapter 3. Academic Press, San Diego, CA, 1989. 

The priority in this chapter lies in the description of small organosubstituted silanes and of small heterocycles that might be precursors for the production of new materials for high tech applications (e. g. polycrystalline silicon for photovoltaic purposes, thin ceramic coatings from CVD processes). 

Such high-tech methods have not yet brought the new superconductors into the marketplace, but they most certainly give manufacturers what they need most from the warmer bulk ceramic materials—the forms that will carry frictionless electrical current and channel its perpetual, enormous power into everything from that wristwatch to flying trains. If the necessary properties can be built into the new superconductors, if the problems that still bedevil them are ironed out—and few, if any, believe that they will not be resolved—then superconductivity, once an exotic plaything, will, like the transistor and the laser, change the very way we live and work. 

Macroscopic properties of ceramic materials are often dominated by localized imperfections such as defects, impurities, surfaces and interfaces. Systematically-doped polycrystalline materials exhibit wider variety of properties as compared with monolithic single crystals. Some of them serve key roles in high-tech society and they are referred to as fine ceramics or advanced ceramics. An ultimate objective of the ceramic science and technology is to understand the nature and functions of the localized imperfections in order to achieve desired performances of materials intellectually without too much accumulation of empirical knowledge. 

A. Larbot, J.A. Alary, C. Guizard, L. Cot emd G. Gillot, New inorganic ultrafiltration membranes preparation and characterization. High Tech. Ceramics, 3 (1987) 143. 

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