Chemical silicon carbides

Figure 3.2 Chemical potential diagrams for the transport of silicon carbide by chlorine, showing that the much greater stability of SiCU than CCI4 makes this process very inefficient, while the use of HCl as the transporting gas can be operated under optimum conditions...

Kirk-Othmer Encylopedia of Chemical Technology, 4th edn., Vol. 4, Silicon Carbide, 1992, pp. 891-911. 

Angelini, P., Chemical Vapor Deposition of Silicon Carbide from Methylsilane and Coating of Nuclear Waste Ceramics, Diss. Abstr. Int, 46(9) 170 (Mar. 1986)... 

Fukutomi, M., Kitajima, M., Okada, M., and Wanatabe, R., Silicon Carbide Coating on Molybdenum by Chemical Vapor Deposition and its Stability under Thermal Cycle Conditions, J Nucl Mater., 87(1) 107-116 (Nov. 1979)... 

Present oxidation-protection systems are based on silicon carbide (SiC), which is applied by pack cementation or by chemical-vapor infiltration (CVI) (see Ch. 4).d ] Boron, zirconium, and other... 

Divakar, R., et al., Silicon Carbide, in Kirk Othmer, Encyclopedia of Chemical Technology, John Wiley Sons, New York (1991)... 

Other ceramic cutting-tool materials include alumina, Si-Al-0-N, alumina-carbide composites and, more recently, a composite of silicon nitride reinforced with silicon carbide whiskers. This last material can be produced by chemical-vapor infiltration (CVI) and has high strength and toughness as shown in Table 18.3.Cl... 

Silicon carbide, SiC [1] and silicon nitride, Si3N4 [2], have been known for some time. Their properties, especially high thermal and chemical stability, hardness, high strength, and a variety of other properties have led to useful applications for both of these materials. 

MOCVD as, 22 153-154 in silicon carbide fiber manufacture, 22 534 thermally activated, 24 744-745 Chemical vapor infiltration (CVI), 26 767 ceramics and, 5 664 Chemical warfare, 5 813-840 defense against, 5 830-837 Chemical warfare agents, detection of, 22 716-717... 

Source of Heat Industrial furnaces are either fuel-fired or electric, and the first decision that a prospective furnace user must make is between these two. Although electric furnaces are uniquely suited to a few appheations in the chemical industry (manufacture of silicon carbide, calcium carbide, and graphite, for example), their principal use is in the metallurgical and metal-treatment industries. In most cases the choice between electric and fuel-fired is economic or custom-dictated, because most tasks that can be done in one can be done equally well in the other. Except for an occasional passing reference, electric furnaces will not be considered further here. The interested reader will find useful reviews of them in Kirk-Othmer Encyclopedia of Chemical Technology (4th ed., vol. 12, articles by Cotchen, Sommer, and Walton, pp. 228-265, Wiley, New York, 1994) and in Marks Standard Handbook for Mechanical Engineers (9th ed., article by Lewis, pp. 7.59-7.68, McGraw-Hill, New York, 1987). 

Ming T, Anders E, Hoppe P, Zinner E (1989) Meteoritic silicon carbide and its stellar sources, implications for galactic chemical evolution. Nature 339 351-354 Minigawa M, Wada E (1984) Stepwise enrichments of along food chains further evidence and the relation between 5 N and animal age. Geochim Cosmochim Acta 48 1135-1140 Mizutani Y, Rafter TA (1973) Isotopic behavior of sulfate oxygen in the bacterial reduction of sulfate. Geochem J 6 183-191... 

Zinc oxide in solid or fine particle form is kept in a reactor cavity that is subjected to irradiation from solar concentrators [92], The dissociation products are zinc (vapor) and oxygen for this first reaction AG=0 at about 2235K [91], The reactor is made of materials like inconel steel, zirconia, silicon carbide or graphite [68,89,92], The graphite is used in special designs to avoid direct contact with chemical species [68], The dissociation products are then cooled rapidly to separate zinc and oxygen, transporting the... 

Silicon carbide is a very hard snbstance with a Young s modulus of 424 GPa [1]. It is chemically inert and reacts poorly (if at all) with any known material at room temperature. The only known efficient etch at moderate temperatures is molten KOH at 400-600°C. It is practically impossible to diffuse anything into SiC. Dopants need to be implanted or grown into the material. Eurthermore, it lacks a liqnid phase and instead sublimes at temperatures above 1,800°C. The vapor constituents during sublimation are mainly Si, SqC, and SiC in specific ratios, depending on the temperature. 

We recently published a chapter in the book Silicon Carbide Recent Major Advances by Choyke et al. [19] that describes SiC gas sensor applications in detail. In this book, we emphasize device properties applications are only briefly reviewed at the end. The device and gas sensing properties of various field-effect chemical gas sensing devices based on SiC are described, and other wide bandgap material devices are reviewed. The detection principle and gas response is explained, and the buried channel SiC-FET device is described in detail. Some special phenomena related to the high-temperature influence of hydrogen at high temperature are also reported. 

---