Boron-carbon-silicon system

E. Rudy, Ternary phase equilibria in transition metal-boron-carbon-silicon systems. Part V. Compendium of phase diagram data. Tech. Rep. AFML-TR—Air Force Mater. Lab. (US.) AFML-TR-65-2 (1969). 

Rudy, E. and Windisch, S. in Ternary Phase Equilibria in Transition Metal-Boron-Carbon Silicon Systems, Part I, Vol. Vll, Technical Report No. AFML-TR-65-2, Wright Patterson Air Force Base, OH, 1966. 

Bor] Borisov, E.V., Gruzin, P.L., Zemskii, S.V., CandMoinCr, Cr-Fe, and Cr-Ta Alloys, Impurity Tracer Diffusion , Diff. Data, 3,266 (1969) (Kinetics, Transport Phenomena, Abstract, 0) [1969Rud] Rudy, E., Ternary Phase EquiUbria in Transition Metal-Boron-Carbon-Silicon Systems. 

The selected value is an average based on the equilibrium data summarized below. Drowart and co-workers have used the Knudsen effusion-mass spectrometric technique to determine the vapor equilibria over the systems SiC-graphite ( ), SiC-silison (2 ) and boron-carbon-silicon (3). 3rd law analysis of the partial pressures of C Si and Si lead to the concordant values -1 ... 

Included in the term nonoxide ceramics are all non-electrically conducting materials in the boron-carbon-silicon-aluminum system. The industrially most important representatives, apart from carbon (see Section 5.7.4), are silicon carbide (SiC), silicon nitride (Si3N4), boron carbide (B4C), boron nitride (BN) and aluminum nitride (AIN). 

Kalinina AA, Sokhor MI, Shamrai FI (1971) Izv Akad Nauk SSSR, Neorg Mat 7 778 (a) Gugel E, Kieffer R, Leimer G, Ettmayer P (1972) Investigation in the ternary system boron-carbon-silicon. Nat Bur Stand Spec Publ, Solid State Chemistry, Proc 5 " Mat Res Symp 364 505 (b) Kieffer R, Gugel E, Leimer G, Ettmayer P (1972) Ber Dt Keram Ges 49 41... 

As discussed above, thermobaric weapons contain monopropellants or secondary explosives and energetic particles. Boron, aluminum, silicon, titanium, magnesium, zirconium and carbon can be considered to be energetic particles. The main advantage of thermobaric systems is that they release large quantities of heat and pressure, often in amounts larger than for only secondary explosives. 

MMCs are usually reinforced by either monofilaments, discontinuous fibers, whiskers, particulates, or wires. With the exception of wires, which are metals, reinforcements are generally made of advanced ceramics such as boron, carbon, alumina and silicon carbide. The metal wires used are made of tungsten, beryllium, titanium, and molybdenum. Currently, the most important wire reinforcements are tungsten wire in superalloys and superconducting materials incorporating niobium-titanium and niobium-tin in a copper matrix. The most important MMC systems are presented in Table 18.5. 

A number of systems have been developed for the functionalization of C-H bonds by their conversion into carbon-boron or carbon-silicon bonds. The substrates can be alkenes (Scheme 3.35), arenes (Schemes 3.36-3.38), heteroarenes (Schemes 3.39-3.41)" ° and even alkanes (Scheme 3.42)." With arenes, the electronic properties of the aromatic ring do not always seem to control the regioselectivity, as mixtures of isomers are often formed. Methyl-substituted aromatics may be borylated on the side chain depending on the choice of catalyst." ... 

This is true of the usual heteroatoms, i.e., nitrogen, oxygen, sulfur, and the halogens. Boron and silicon are less electronegative than carbon and for them the conclusions of Rule 1 (Section 4.6) would be inverted. However, these elements play a relatively small role in conjugated systems. 

Extreme aging conditions show the importance of silicon and boron in the protection of carbon-based systems against oxidation. Thermoset and ceramic compositions formed from mixtures of 1 and 3a show outstanding oxidative stability. Both compounds contain acetylenic units for thermal conversion to network polymers. The resistance to oxidation... 

In the molecule of 4-methylene-3-borahomoadamantane derivative 79, the structure of which was determined by X-ray analysis, the six carbon atoms of the triene system, the two boron and two silicon atoms all lie in one plane within experimental error (mean deviation 1.4 pm). The boron atoms deviate from the trigonal-planar geometry, since the sum of bond angles around the atoms is only 355.8° instead of 360°, as usually encountered in triorganoboranes. Considerable distortions of the bond angles at the terminal C-C double bond occurs in the vicinity of the boron atoms B-C(4)-C(ll) 130.60(19)° and B-C(4)-C(5) 107.38(17)° <2002CEJ1537>. 

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