Rocket boron

Other boron hydrides are known, most of them having the general formula B H + 4- for example pentaborane, B5H9, decaborane, BjqHi4. Each can be made by heating diborane in suitable conditions for example at 420 K, decaborane is obtained. Boron hydrides have been tried as rocket fuels. 

Amorphous boron is used in pyrotechnic flares to provide a distinctive green color, and in rockets as an igniter. 

It also has lubricating properties similar to graphite. The hydrides are easily oxidized with considerable energy liberation, and have been studied for use as rocket fuels. Demand is increasing for boron filaments, a high-strength, lightweight material chiefly employed for advanced aerospace structures. 

Hydrazine—borane compounds are made by the reaction of sodium borohydride and a hydrazine salt in THF (23,24). The mono-(N2H4 BH ) and di-(N2H4 2BH2) adducts are obtained, depending on the reaction conditions. These compounds have been suggested as rocket fuels (25) and for chemical deposition of nickel—boron alloys on nonmetallic surfaces (see Metallic COATINGS) (26). 

Boron has been studied as a possible fuel for soHd fuel ramjets (10,11). Fine particle sized boron, where the average particle size is 0.3 )J.m, has been studied for use as a gas-generating agent for soHd fuel ram rockets (12). 

Boron mixed with an oxidizer is used as a pyrotechnic. This ordnance appHcation for missiles and rockets is predominandy military. However, boron is also used in air bags, placed in automobiles as safety devices, for initiating the sodium azide [26628-22-8] which fiHs the bag with nitrogen (13). Other boron compounds are also used in the air-bag pyrotechnic appHcation. 

Polyhedral Boron Hydrides. These are used in neutron capture therapy of cancers (254), and as bum rate modifiers (accelerants) in gun and rocket propellant compositions. 

Historically, polymer-matrix composite materials such as boron-epoxy and graphite-epoxy first found favor in applications, followed by metal-matrix materials such as boron-aluminum. Ceramic-matrix and carbon-matrix materials are still under development at this writing, but carbon-matrix materials have been applied in the relatively limited areas of reentry vehicle nosetips, rocket nozzles, and the Space Shuttle since the early 1970s. 

Evolution did not use this element, only in certain plants is it important as a trace element. The element became well-known because of heat-resistant borosilicate glasses. Boranes are chemically interesting as B-H bonds react very specifically. Perborates are used in laundry detergents (Persil). The hardness of cubic boron nitride approaches that of diamond. Amorphous (brown) boron burns very quickly and gives off much heat and is therefore used in solid-propellant rockets and in igniters in airbags. 

Since the early work of Stock, other boron hydrides have been synthesized. Some of these compounds have been used as fuel additives, and they have found some application in high-energy rocket fuels. However, because B203(s) is a product of the reaction, the use of these materials in that way causes some problems. The boron hydrides will all bum readily to produce B203 and water,... 

Uses. Amorphous boron is used as an addictive in pyrotechnic mixtures, solid rockets propellants, explosives, etc. Refractory metal borides are used as addic-tives to cemented carbides. High purity boron is used in electronics as a dopant to... 

Alfred Stock (1876-1946) studied the hydrides of some of these metal-like elements. A hydride occurs when hydrogen gains (or shares) an electron rather than losing its single electron when it combines with metals or metallic-like elements. Stock spent years experimenting with boron hydrides (B Hg and BH ), which were used as hydrogen-based rocket fuels powerful enough to lift rockets into space. 

A hydride of boron that is combined with hydrogen is an effective booster for rocket... 

Boron is an important ingredient of pyrolants. A mixture of boron and potassium nitrate particles forms a pyrolant used as an igniter in rocket motors. The stoichiometric mixture of B and KNO3 reacts according to ... 

Boron is one of the essential materials for obtaining high specific impulse of a ducted rocket However, the combustion efficiency of boron-containing gas-generating pyrolants is low due to incomplete combustion of the boron particles in the ramburner.[i3-i l Fig. 15.20 shows the combustion temperature ofa boron-containing pyrolant with and without boron combustion as a function of air-to-fuel ratio, 8. A typical boron-containing pyrolant is composed of mass fractions of boron particles b(0-30), ammonium perchlorate ap(0.40), and carboxy-terminated polybutadiene ctpb(0-30). If the boron particles burn completely in the ramburner, the maximum combustion temperature reaches 2310 K at 8 = 6.5 and v = Mach 2 p =... 

MPa) under conditions of sea-level flight However, if no boron combustion occurs, the temperature decreases to 1550 K under the same flight conditions. The combustion efficiency of boron particles is an important parameter for obtaining high specific impulse of ducted rockets. 

Schadow, K., Boron Combustion Characteristics in Ducted Rockets, Combustion Science and Technology, Vol. 5, 1972,... 

Schadow, K., Experimental Investigation of Boron Combustion in Air-Augmented Rockets, AIAA Journal, Vol. 7, 1974,... 

The most important application of boron is to make fibers or whiskers of single crystal or ceramic crystal. The addition of boron to metals, alloys, or other solids, imparts resistance to plastic flow, and thereby produces unusual strength in the material. Amorphous boron is used in rockets as an igniter, and in pyrotechnic flares to give green color. Many boron compounds, such as borax, boron hydrides, and boron hahdes, have important commercial applications (see individual compounds). 

Borani — Propellenti liquidi per razzi (Liquid Rocket Propellants) consist of liquid hydrogen with boron or other light element, such as beryllium (Ref 31, p 129)... 

Exotic Fuels. Accdg to Ref 1, this name is applied to high energy fuels (HEF) for jets and rockets which have higher performance rates than hydrocarbon fuels, such as kero sene or JP-6, etc. The term has also been used eo refer specifically to those jet and rocket fuels based on boron hydrides. Such fuels, known as Boranes, are described in Ref 2... 

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