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Materials Handbook 15th ed - G. Brady_ H. Clauser_ J. Vaccari (McGraw-Hill_ 2011) WW Part 7

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Tham khảo tài liệu 'materials handbook 15th ed - g. brady_ h. clauser_ j. vaccari (mcgraw-hill_ 2011) ww part 7', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 420 FULLERENES burns with high flame speed and high heat. It is used to produce the boron hydrides such as decarborane B10H14 or HH H BB H 5HH employed for boron fuels and for making boron plastics. Sodium boron hydride a white crystalline solid of composition NaBH4 made by reacting sodium hydride with methyl borate is also used to produce the boranes for fuels. Triethyl borane C2H5 B used for jet fuels and as a flame-speed accelerator is a colorless liquid. It is spontaneously flammable its vapors igniting with oxygen. Any element or chemical which causes spontaneous ignition of a rocket fuel is called a hypergolic material. Chemical radicals are potential high-energy fuels as the recombining of them produces high specific impulses. But chemical radicals normally exit only momentarily and are thus not stable materials and in general are not commercial fuels. Ion propellants operate on the principle that like charges repel each other and the fuel is an ion-plasma jet actually formed outside the engine. The original fuel is a metal such as cesium from which electrons can be stripped by passing the vapor through a hot screen leaving positive cesium ions which are formed into a beam and exhausted from the jet thrust to be electronically neutralized in the ionized plasma. FULLERENES. Introduced by researchers at Rice University in the mid-1980s as large carbon molecules having 60 or more carbon atoms arranged in cagelike pseudospheres similar in shape to Buckminster Fuller s geodesic dome and thus also called bucky balls. Carbon 60 or C60 molecules are a new form of carbon with potential for use in steel catalysts lubricants superconductors diamond synthesis monocrystalline film and as building blocks for high-strength polymers. At Argonne National Laboratory C60 has been used as a direct source of carbon to grow diamond film of ultrafine grain size some 6 times faster than by conventional methods. It eliminates the need for hydrogen and nitrogen and the chance of .