Ceramic precursors

Metallacarboranes. These are used in homogeneous catalysis (222), including hydrogenation, hydrosilylation, isomerization, hydrosilanolysis, phase transfer, bum rate modifiers in gun and rocket propellants, neutron capture therapy (254), medical imaging (255), processing of radioactive waste (192), analytical reagents, and as ceramic precursors. 

Infiltration (67) provides a unique means of fabricating ceramic composites. A ceramic compact is partially sintered to produce a porous body that is subsequently infiltrated with a low viscosity ceramic precursor solution. Advanced ceramic matrix composites such as alumina dispersed in zirconia [1314-23-4] Zr02, can be fabricated using this technique. Complete infiltration produces a homogeneous composite partial infiltration produces a surface modified ceramic composite. 

Ceramic Orarnic membranes are made generallvbv the sol-gel process, the siiccessiv e deposition of ev er smaller ceramic precursor... 

The first type of polycarbosilane synthesized by using ADMET methodology was a poly[carbo(dimethyl)silane].14c Linear poly(carbosilanes) are an important class of silicon-containing polymers due to their thermal, electronic, and optical properties.41 They are also ceramic precursors to silicon carbide after pyrolysis. ADMET opens up a new route to synthesize poly(carbosilanes), one that avoids many of the limitations found in earlier synthetic methods.41... 

Ceramic boards are currently widely used in high-performance electronic modules as interconnection substrates. They are processed from conventional ceramic precursors and refractory metal precursors and are subsequently fired to the final shape. This is largely an art a much better fundamental understanding of the materials and chemical processes will be required if low-cost, high-yield production is to be realized (see Chapter 5). A good example of ceramic interconnection boards are the multilayer ceramic (MLC) stractures used in large IBM computers (Figure 4.11). These boards measure up to 100 cm in area and contain up to 33 layers. They can interconnect as many as 133 chips. Their fabrication involves hundreds of complex chemical processes that must be precisely controlled. 

The use of sol-gel techniques to prepare ceramic powders has recently attracted much interest in academia and industry. Sol-gel techniques involve dissolving a ceramic precursor (e g., tetramethyl orthosilicate) in a solvent and... 

Simon P.F.W., Ulrich R., Spiess H.W., and Wiesner U. Block copolymer-ceramic hybrid materials from organically modified ceramic precursors, Chem. Mater., 13, 3464, 2001. 

Narula CK (1995) Ceramic Precursor Technology and Its Applications. Marcel Dekker, New York... 

Ceramic Ceramic membranes are made generally by the sol-gel process, the successive deposition of ever smmler ceramic precursor sph eres, followed by firing to form multitube monoliths. The diameter of the individual channels is commonly about 2 to 6 mm. Monoliths come in a variety of shapes and sizes. A 19-channel design is common. One manufacturer makes large monoliths with square channels. 

Two examples stand out research on ceramic precursors and research on biomaterials via so-called biomimetic approaches. I had started the systematic organometallic precursor work for making ceramic powders in a series of a few dozen papers starting in 1948 (1, 2). By the mid-1950s I had shown that inorganic sols did essentially as well and were orders of magnitude cheaper. The very sophisticated ceramic precursor work, now a decade old, has yet to demonstrate a special niche for itself in any real examples with unique properties. 

A proposed reaction scheme for formation of polymethyldisylazane oligomer, a ceramic precursor, has been developed, giving some insight into structural features of this type of resin-like molecule. In addition, the cause for broad featureless signals in the NMR spectroscopy of these polymers has been determined to be the multiplicity of environments about the Si atoms which develop early in the reaction before appreciable polymerization occurs. 

Silicon-containing ceramic precursors constitute a broad family of materials discussed thoroughly in a number of recent publications, where broad introduction into the field of modern ceramics is easy to find. Thus, Laine and... 

The production of fine particles that are either desirable (polymer colloids, ceramic precursors, etc.) or undesirable (soot, condensed matter from stack gases, etc.) involves chemical reactions, transport processes, thermodynamics, and physical processes of concern to the chemical engineer. The optimization and control of such processes and the assurance of the quality of the product requires an understanding of the fundamentals of microparticles. 

Mass of ceramic expressed as a percentage of the mass of the ceramic precursor the ceramization process. 

Ceramic derived from a polymeric ceramic precursor. 

Process in which a ceramic precursor is converted into a ceramic. 

Note 2 Pyrolysis is the commonly used term for a high-temperature treatment that converts a ceramic precursor to a ceramic. 

Some microelectronic and ceramic precursors and materials silicon SiH4 SiCU GaAs AsHj... 

Finally, the combination of dendrimers and organometallic entities as fundamental building blocks affords an opportunity to construct an infinite variety of organometallic starburst polymeric superstructures of nanoscopic, microscopic, and even macroscopic dimensions. These may represent a promising class of organometallic materials due to their specific properties, and potential applications as magnetic ceramic precursors, nonlinear optical materials, and liquid crystal devices in nanoscale technology. 

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