Polymeric cyanoborane, (CNBH2),, is a material readily prepared by passing hydrogen chloride through an ether suspension of sodium cyanotrihydroborate. This polymeric material was volatilized in a CVD reactor to produce, at 6OO0C, amorphous films containing boron, nitrogen, and carbon. Residual carbon present in the films was removed by ammonia treatment at 800°C, producing nearly stoichiometric boron nitride films that were adherent to a variety of substrates including silicon. [
Y-12 Plant, Oak Ridge, Tennessee, USA UF,, UF, and UF, have been studied by X-ray photoelectron spectroscopy. U 4f7/2 binding energies for these compounds were observed to be 384.9, 383.4 and 382.3 eV, respectively. The corresponding U 4fSj2 energies were 395.7, 394.2 and 393.2 eV. Solid UF, was formed by condensation of a molecular beam onto Ni and Cu substrates at -80 O C . UF4 was produced by reaction of the UF, beam at higher substrate temperatures (-30 OC and 25 "C). UF, was produced at higher temperature and pressure by reaction of Cu and UF,. In the X-ray photoelectron spectroscopy vacuum chamber, the UF, converted slowly to UF,, probably by disproportionation and loss of UF,.
Aluminum alloys, because of their face-centered cubic structure, offer distinct advantages as structural materials for use at cryogenic temperatures, at which some other metals are brittle. Accordingly, tests of seven alloys (2014-T6, 2219-T62, 5456-H321, 6061-T6, 7075-T6, 7079-T6, and 7178-T6) using smooth and sharply notched, longitudinal and transverse specimens of plain and welded 1/8-in. sheet were made at 75, −320 (liquid nitrogen), and −423 F (liquid hydrogen). As parent metal, all alloys were found to be suitable for use at these temperatures, exhibiting ductile behavior throughout the full temperature range. For welded structures or in applications where notch sensitivity is important, the use of some of the higher strength heat treated alloys may necessitate special precautions in design. While as-welded joints in each alloy had lower strengths than the parent metal at all temperatures, welds in alloy 2219-T62 when reheat treated had strengths equal to those of the parent metal. The sharp-notch sensitivities of welds in some alloys were less than those of the parent metals.
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