Metal carbides silicone carbide

Developments in metal-matrix composites technology has resulted in aluminum matrix materials filled with siUcon carbide [409-21 -2] SiC, (see Carbides, silicon carbide) particles (15 to 60 vol %) that provide the possibihty of weight reduction for brakes (20). These composite materials are being tested and evaluated. 

Silicon-containing ceramics include the oxide materials, silica and the silicates the binary compounds of silicon with non-metals, principally silicon carbide and silicon nitride silicon oxynitride and the sialons main group and transition metal silicides, and, finally, elemental silicon itself. There is a vigorous research activity throughout the world on the preparation of all of these classes of solid silicon compounds by the newer preparative techniques. In this report, we will focus on silicon carbide and silicon nitride. 

The metal-insulator-silicon carbide MISiC sensors function over a large temperature range, 100-700°C. Their gas response can be divided into two different temperature regimes with the break-over point around 600°C. 

Note that the silicide layer may grow not only between silicon and a transition metal, but also between a silicon-containing phase and a transition metal or an intermetallic compound. Such layers are known to occur in the process of brazing the transition metals by their own melts with Si3N4-base ceramics239 and also during the interaction of transition metals with silicon carbide.238 240 245... 

As with the hydrides (Chap. 2), the carbides are divided into three classes—the covalent, the saltlike, and the metallic (or interstitial). The volatile covalent carbides (for example, CC14, (CN)2, CH4, and CS2) are discussed elsewhere of the nonvolatile covalent carbides, silicon carbide (carborundum, SiC), is by far the most important. Although there are three known crystal forms of this compound, we may, for simplification, imagine it as a diamond structure in which every alternate carbon atom is replaced by a silicon atom. Thus it is not surprising that this compound is almost as hard and chemically inert as is diamond itself. 

The dip and spin coating methods are the most practiced techniques as indicated in the open literature. Many materials have been made into porous membranes by this route including the more commonly referenced materials such as metal oxides, silicon carbide, silicon nitride, silicon and aluminum oxynitrides and glasses. 

Hwang, E. H., Adam, S. and Das Sarma, S. (2007),Transport in chemically doped graphene in the presence of adsorbed molecules. Physical Review B, 76,195421. Inone, H., Andersson, M., Ynasa, M., Kida, T, Lloyd Spetz, A. and Shimanoe, K. (2010), CO2 sensor combining a metal-insulator silicon carbide (MISiC) capacitor and a binary carbonate. Electrochemical and Solid-State Letters, 14(1), J4-7. Doi 10.1149/1.3512998... 

Nakagomi, S., Tobias, R, Baranzahi, A., Lundstrom, I., Martensson, P. and Lloyd Spetz, A. (1997), Influence of carbon monoxide, water and oxygen on high temperature catalytic metal-oxide silicon carbide structures. Sensors and Actuators 5,45,183-91. 

Spetz, A., Arbab, A. and Lundstrom, I. (1992), Gas sensors for high temperature operation based on metal oxide silicon carbide (MOSiC) devices, in Proceedings of Eurosensors VI, San Sebastian, Spain, 19-23. 

Baranzahi, A., Spetz, A. L. and Lundstrom, I. (1995) Reversible hydrogen annealing of metal-oxide-silicon carbide devices at high-temperatures . Applied Physics Letters, 67(21), 3203-3205. 

Svenningstorp, H.,Tobias, E, Lundstrom, L, Salomonsson, E, Martensson, R, Ekedahl, L. G. and Spetz, A. L. (1999) Influence of catalytic reactivity on the response of metal-oxide-silicon carbide sensor to exhaust gases . Sensors and Actuators B-Chemical, 57(1-3), 159-165. 

Covalence. Carbon bonding is covalent, that is, the atoms share a pair of electrons. Such covalent bonds are strong since the carbon atom is small and four of its six electrons (the four sp valence electrons) form bonds. This is the case for the two covalent carbides, silicon carbide and boron carbide (see Ch. 7). The bonding in interstitial carbides is not as straightforward and is a combination of covalent, metallic, and ionic bonding as reviewed in Sec. 6.0. 

The MDF pastes are also filled with metallic powders, silicon carbide, fine sand and with other kinds of hard materials to obtain particular properties. 

Tobias, R, Baranzahi, A., Spetz, A.L. (1997). Fast chemical sensing with metal-insulator silicon carbide structures. IEEE Electron Deoice Lett., Vol.18, No. 6, pp. 287-289 Tomchenko, A. A., Harmer, G. R, Marquis, B. T. Allen, J. W. (2003). Semiconducting metal oxide sensor array for the selective detection of combustion gases. Sensors and Actuators B, Vol. 93, pp. 126-134... 

Chlorine Ammonia, acetylene, alcohols, alkanes, benzene, butadiene, carbon disulflde, dibutyl phthalate, ethers, fluorine, glycerol, hydrocarbons, hydrogen, sodium carbide, flnely divided metals, metal acetylides and carbides, nitrogen compounds, nonmetals, nonmetal hydrides, phosphorus compounds, polychlorobi-phenyl, silicones, steel, sulfldes, synthetic rubber, turpentine... 

Chrome—nickel alloy heating elements that commonly ate used in low temperature furnaces are not suitable above the very low end of the range. Elements commonly used as resistors are either silicon carbide, carbon, or high temperature metals, eg, molybdenum and tungsten. The latter impose stringent limitations on the atmosphere that must be maintained around the heating elements to prevent rapid element failure (3), or the furnace should be designed to allow easy, periodic replacement. 

Silicon (3), which resembles metals in its chemical behavior, generally has a valence of +4. In a few compounds it exhibits a +2 valence, and in silicides it exists as a negative ion and largely violates the normal valency rules. Silicon, carbon, germanium, tin, and lead comprise the Group 14 (IVA) elements. Silicon and carbon form the carbide, SiC (see Carbides). Silicon and germanium are isomorphous and thus mutually soluble in all proportions. Neither tin nor lead reacts with silicon. Molten silicon is immiscible in both molten tin and molten lead. 

Carbon forms binary compounds with most elements those with metals are considered in this section whilst those with H, the halogens, O, and the chalcogens are discussed in subsequent sections. Alkali metal fullerides and encapsulated (endohedral) metallafullerenes have already been considered (pp. 285, 288 respectively) and met-allacarbohedrenes (metcars) will be dealt with later in this section (p. 300). Silicon carbide is discussed on p. 334. General methods of preparation of metal carbides are ... 

An., Continuous Silicon Carbide Metal Matrix Composites, Technical Brochure, Textron Specialty Materials, Lowell, MA... 

Carbides produced by CVD include the refractory-metal carbides and two important non-metallic carbides boron carbide and silicon carbide. The refractory-metal carbides consist of those of the nine transition elements of Groups IVa, Va, and Via and the 4th, 5th, and 6th Periods as shown below in Table 9.1. 

The atomic and crystalline structure of the two non-metallic carbides, boron and silicon carbides, is less complex than that of the... 

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