Silicon dioxide ceramics

Some silicon dioxide ceramics are made by the sol-gel process. In this process, an organic silicon compound is dissolved in water and polymerized into a network structure. As the gel forms, many cross-links are formed. These cross-links form a rigid, strong matrix that is free of... 

Ceramic materials are typically noncrystalline inorganic oxides prepared by heat-treatment of a powder and have a network structure. They include many silicate minerals, such as quartz (silicon dioxide, which has the empirical formula SiO,), and high-temperature superconductors (Box 5.2). Ceramic materials have great strength and stability, because covalent bonds must be broken to cause any deformation in the crystal. As a result, ceramic materials under physical stress tend to shatter rather than bend. Section 14.22 contains further information on the properties of ceramic materials. 

Silicon dioxide, 22 380. See also Amorphous silica Quartz in ceramics, 5 582... 

Silica, or silicon dioxide, occurs in various forms including chalcedony, which is a decorative material chert, which is used in abrasives flint, which is used in abrasives and ceramics jasper, which is used for decorative purposes quartz, which is a constituent of sand tripoli, which is found in scouring powders, polishers, and fillers cristobalite, which is used in high temperature casting and specialty ceramics diatomaceous earth, which is used in filtration processes and as a filler and finally, silica gel, which is used in dehydrating and drying. Note, however, that the material of concern is silica, and not silicates, which are relatively harmless derivatives of silica, nor silicones, synthetic materials used especially as lubricants. Neither silicates nor silicones cause proliferative conditions. 

The type of attack that occurs in liquid media is highly dependent on the chemical nature of the liquid—that is, molten metal, molten ceramic, or aqueous solution. We will consider two industrially important cases attack by molten metals and attack by aqueous media. The attack of most metal oxide ceramics by molten metals involves a simple exchange of one metal ion for another. For example, silicon dioxide in contact with molten aluminum is susceptible to the following corrosion reaction ... 

In 1992, R.M. Laine (University of Michigan, Ann Arbor) announced the development of a process that transforms sand and other forms of silica into reactive silicates that can be used to synthesize unusual silicon-based chemicals, polymers, glasses, and ceramics. The Lame procedure produces pentacoordinate silicates directly from low-cost raw materials—silicon dioxide,ethylene glycol, and an alkali base. The mixture is approximately a 60 1 ratio of silica gel, fused silica (or sand) to metal hydroxide and ethylene... 

Adhesion of polyimides to inorganic substrates is of great importance to the microelectronics industry [1, 2]. The polyimide films are deposited most often by spin coating the polyamic acid (PAA) usually from a TV-methylpyrrolidone (NMP) solution onto the substrate surface followed by thermal imidization at temperatures up to 400<>C. The most studied polyimide is the pyromellitic dianhydride-oxydianiline (PMDA-ODA), which exhibits excellent mechanical and dielectric properties, but not so good adhesion characteristics. The latter has been generally overcome by application of an adhesion promoter, such as y-aminopropyltriethoxysilane [3-7]. The reactions of APS (coated from water solution) with the silicon dioxide surface as well as with polyamic acid have been well characterized by Linde and Gleason [4] however, we do not have such detailed information available on APS interaction with other ceramic surfaces. 

Ceramic, The ceramic substrate is made from a mixture of silicon dioxide, talc, and kaolin to make the compound cordierite [12182-53-5]. Cordierite possesses a very low coefficient of thermal expansion and is thermal-shock resistant. The manufacturing process involves extruding the starting mixture (which is mixed with water and kneaded into a sort of dough) through a complex die to form the honeycomb structure. The extmded piece is dried and fired in a kiln to form the cordierite. The outside or circumferential dimension is formed by the die, and the length is cut later with a ceramic saw. 

An important oxide in ceramics is silicon dioxide Si02 in the form of the minerals quartz and quartz sand (with aluminium oxide as a... 

In this chapter we have considered three-dimensional ceramic constructions and nature s three-dimensional crystalline structures and glasses. There are many similarities between the construction of a ceramic work of art and the construction of a crystalline solid or glass. In both cases, units are built into a structure. The units are bonded together in a variety of ways. Both can result in pleasing works for the viewer to enjoy. A quartz crystal, made of silicon dioxide (Si02), can be just as beautiful as a carefully crafted ceramic piece. Particular elements of design make these objects beautiful. When considering ceramic pieces and natural crystals, texture is an important element. 

Some of the most common combinations used in the development of new ceramic composites involve the use of silicon carbide, silicon nitride, aluminum oxide, silicon dioxide, and mullite (a form of aluminum sulfate (Al2[S04]3). Each of these compounds can he used either as the reinforcement or as the matrix in a composite. 

Sand (silicon dioxide) and coke (carbon) are combined to form silicon carbide (SiC), a compound used in high-strength ceramic materials. 

Chipmakers would like to be able to use a silicon dioxide, the material from which virtually all the world s microchips are made. But until very recently, it had not performed well with the new ceramics because the superconductor s components mix with those of the silicon, causing a rearrangement of elements. The resulting material may no longer have the yttrium, barium, and copper at... 

Even before alchemy became a subject of study, many chemical reactions were used and the products applied to daily life. For example, the first metals used were probably gold and copper, which can be found in the metallic state. Copper can also be readily formed by the reduction of malachite—basic copper carbonate, Cu2(C03)(0H)2—in charcoal fires. Silver, tin, antimony, and lead were also known as early as 3000 BC. Iron appeared in classical Greece and in other areas around the Mediterranean Sea by 1500 BC. At about the same time, colored glasses and ceramic glazes, largely composed of silicon dioxide (Si02, the major component of sand) and other metallic oxides, which had been melted and allowed to cool to amorphous solids, were introduced. 

A number of silicon compounds have important uses. Silicon dioxide (sand) is used in the manufacture of glass, ceramics, abrasives, as a food... 

Numerous ceramics are deposited via chemical vapor deposition. Oxide, carbide, nitride, and boride films can all be produced from gas phase precursors. This section gives details on the production-scale reactions for materials that are widely produced. In addition, a survey of the latest research including novel precursors and chemical reactions is provided. The discussion begins with the mature technologies of silicon dioxide, aluminum oxide, and silicon nitride CVD. Then the focus turns to the deposition of thin films having characteristics that are attractive for future applications in microelectronics, micromachinery, and hard coatings for tools and parts. These materials include aluminum nitride, boron nitride, titanium nitride, titanium dioxide, silicon carbide, and mixed-metal oxides such as those of the perovskite structure and those used as high To superconductors. 

Silicon dioxide is the most widely used ceramic material in the semiconductor industry, and the majority of Si02 deposits in microelectronic circuits are formed by CVD. Silica layers are used as diffusion sources, intermetallic dielectrics, and dopant and etch barriers in the microelectronics industry. CVD of Si02 is also commonly used in manufacturing energy-efficient glass windows, surface coatings for fiber optics, and micromechanical applications. ... 

Problem Silicon carbide (SiC) is an important ceramic material that is made by allowing sand (silicon dioxide, Si02) to react with powdered carbon at high temperature. Carbon monoxide is also formed. When 100.0 kg of sand is processed, 51.4 kg of SiC is recovered. What is the percent yield of SiC from this process ... 

Lagerlof KPD, Mitchell TE, Heuer AH (1989) Lattice diffusion kinetics in undoped and impurity-doped sapphire (a-Al203) A dislocation loop annealing stndy. J Am Ceram Soc 72 2159-2179 Lamkin, MA, Riley, FL, Fordham RJ (1992) Oxygen mobility in silicon dioxide and silicate glasses A review. J Eur Ceram Soc 10 347-367... 

The primary use of silicon dioxide is in the building industry. It is used to make ceramics, enamels, concrete, and specialized silica bricks used as refractory materials. It is also one of the raw materials from which all kinds of glass are made. Vitreous silicon dioxide is an important constituent of specialized types of glass, such as that used in making laboratory equipment, mirrors, windows, prisms, cells, and other kinds of optical devices. Silicon dioxide is also used as an anti-caking or thickening agent in a variety of foods and pharmaceutical products. Some other applications of silicon dioxide include ... 

Surface moisture is a problem of concern in ceramic powders, and IR has been used to characterize the surface groups of -OH and -H [58,63,64]. IR was also applied to characterize chemically bound hydrogen in chemical vapor-deposited silicon nitride at various ammonia-silane ratios [65]. Surface silicon dioxide on SiC powders was determined by photoacoustic IR and diffuse reflectance IR spectroscopy [66,67]. IR spectroscopy was also used to study the surface oxidation of SiC and SisN4 [68,69]. 

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