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Chemical bonding in hard boron-nitride multilayers

Description: The oxides and nitrides of boron show great potential for use as hard, wear resistant materials. However, large intrinsic stresses and poor adhesion often accompany the hard coatings as found for the cubic boron-nitride phase. These effects may be moderated for use of a layered structure. Alternate stiff layers of boron and compliant layers of nitride are formed by modulating the sputter gas composition during deposition of boron target. The B/BN thin films are characterized with transmission electronic microscope to evaluate the microstructure, nanoindentation to measure hardness and ex-ray absorption spectroscopy to determine chemical bonding. The effects of layer pair spacing on chemical bonding and hardness are evaluated for the B/BN films.
Date: June 1, 1997
Creator: Jankowski, A.F. & Hayes, J.P.
Partner: UNT Libraries Government Documents Department

Studies of the Corrosion of Aisi 304 Stainless Steel and Aisi 4135 Carbon Steel Exposed to Saturated Solutions of Boric Acid

Description: AISI 304 stainless steel and AISI 4135 carbon steel specimens were exposed to five wt.% (70 F) and thirteen wt.% (140 F) boric acid solutions. These are essentially saturation concentrations. After four weeks exposure it was found that the AISI 304 stainless steel was not attacked under these conditions but that the carbon steel had developed considerable corrosion products in the form of scale. It was found that the attack on carbon steel at 70 F in a five wt.% boric acid solution was greatly reduced by the addition of sufficient base to neutralize the solution. A thirteen wt.% boric acid solution badly attacked the carbon steel at 140 F even when adjusted to neutral pH conditions. (auth)
Date: November 1, 1958
Creator: Bergen, C. R. & Whyte, D. D.
Partner: UNT Libraries Government Documents Department

Preparation of ultralow-friction surface films on vanadium diboride.

Description: In this paper, we present a simple annealing procedure (which we refer to as ''flash-annealing'' because of short duration) that results in the formation of an ultralow friction surface film on vanadium diboride (VB{sub 2}) surfaces. This annealing is done in a box furnace at 800 C for a period of 5 min. During annealing, the exposed surface of the VB{sub 2} undergoes oxidation and forms a layer of boron oxide (B{sub 2}O{sub 3}). In open air, the B{sub 2}O{sub 3} layer reacts spontaneously with moisture and forms a boric acid (H{sub 3}BO{sub 3}) film. The friction coefficient of a 440C steel pin against this H{sub 3}BO{sub 3} film is {approx}0.05, compared to 0.8 against the as-received VB{sub 2}. Based on Raman spectroscopy and electron microscopy studies, we elucidate the ultralow friction mechanism of the flash-annealed VB{sub 2} surfaces.
Date: October 14, 1996
Creator: Erdemir, A.; Fenske, G. R. & Halter, M.
Partner: UNT Libraries Government Documents Department


Description: Thin Li/sup 6/F and B/sub 2/O/sub 3/ films were nondestructively analyzed by bombarding them with neutrons, obtaining the pulseheight distribution of the resultant charged particles, and determinlng the number of reactions from the area under each peak in the spectrum. The results agreed within the precision of this method with results of a flame analysis. This method is more accurate and sensitive than conventional neutron activation methods. (D.C.W.)
Date: January 1, 1962
Creator: Finston, H.L.; Wellwart, Y. & Bishop, W.
Partner: UNT Libraries Government Documents Department


Description: The thermodynamic properties of refractory borides, carbides, nitrides, and oxides of some 31 elements are compiled. Several tables for elements and compounds not previously reported are presented, and the experimental spectroscopic studies of the vapor of boron oxide and hydroxide are discussed. (R.J.S.)
Date: December 15, 1962
Creator: Schick, H.L.; Anthrop, D.F.; Dreikorn, R.E.; Feber, R.C.; Hanst, P.L.; Panish, M.B. et al.
Partner: UNT Libraries Government Documents Department

X-ray Raman scattering in H-BN observed by soft x-ray fluorescence spectroscopy

Description: Raman scattering of soft x-rays is observed in h-BN using monochromatic soft x-rays just below the B K absorption edge. The inelastic features are visible below threshold, track with the excitation energy, go through a resonance as the excitation is tuned to the B ls core exciton energy, and finally evolve into normal fluorescence as the excitation is raised above the energy needed to excite the B ls electron into the conduction band. The inelastic energy loss is identified as an excitation of valence {sigma} electrons into the {pi}* valence exciton state; at resonance and above, {pi} {minus} {pi}* transitions are also observed. At resonance, a sideband on the elastic peak Ls observed, which gives evidence of additional electronic and phonon loss processes. Very similar results have also been observed for B{sub 2}O{sub 3}.
Date: March 1, 1995
Creator: Jia, J.J.; Callcott, T.A.; Carlisle, J.A.; Terminello, L.J.; Asfaw, A.; Ederer, D.L. et al.
Partner: UNT Libraries Government Documents Department


Description: Studies of reflector control for the Advanced Engineering Test Reactor were made. The performance of various parts of the reflector control system model such as the safety reflector and the water jet educator, boric acid injection, and demineralizer systems is discussed. The experimental methods and results obtained are discussed. Four reflector control schemes were studied. The schemes were a single-region and three-region reflector schemes two separate reflectors, and two connected reflectors. Calculations were made of shim and safety reflector worth for a variety of parameters. Safety reflector thickness was varied from 7.75 to 0 inches, with and without boron. Boric acid concentration was varied from 100 to 2% of saturation in the shim reflectors. Neutron flux plots are presented (C.J.G.)
Date: October 21, 1959
Creator: Bertelson, P.C. & Francis, T.L.
Partner: UNT Libraries Government Documents Department

Photoacoustically Measured Speeds of Sound and the Equation of State of HBO2: On Understanding Detonation with Boron Fuel

Description: Elucidation of geodynamic, geochemical, and shock induced processes is limited by challenges to accurately determine molecular fluid equations of state (EOS). High pressure liquid state reactions of carbon species underlie physiochemical mechanisms such as differentiation of planetary interiors, deep carbon sequestration, propellant deflagration, and shock chemistry. In this proceedings paper we introduce a versatile photoacoustic technique developed to measure accurate and precise speeds of sound (SoS) of high pressure molecular fluids and fluid mixtures. SoS of an intermediate boron oxide, HBO{sub 2} are measured up to 0.5 GPa along the 277 C isotherm. A polarized exponential-6 interatomic potential form, parameterized using our SoS data, enables EOS determinations and corresponding semi-empirical evaluations of >2000 C thermodynamic states including energy release from bororganic formulations. Our thermochemical model propitiously predicts boronated hydrocarbon shock Hugoniot results.
Date: March 9, 2010
Creator: Zaug, J M; Bastea, S; Crowhurst, J; Armstrong, M; Fried, L & Teslich, N
Partner: UNT Libraries Government Documents Department

Recovery of fissile materials from plutonium residues, miscellaneous spent nuclear fuel, and uranium fissile wastes

Description: A new process is proposed that converts complex feeds containing fissile materials into a chemical form that allows the use of existing technologies (such as PUREX and ion exchange) to recover the fissile materials and convert the resultant wastes to glass. Potential feed materials include (1) plutonium scrap and residue, (2) miscellaneous spent nuclear fuel, and (3) uranium fissile wastes. The initial feed materials may contain mixtures of metals, ceramics, amorphous solids, halides, and organics. 14 refs., 4 figs.
Date: March 1, 1997
Creator: Forsberg, C.W.
Partner: UNT Libraries Government Documents Department

PbO-free glasses for low temperature packaging

Description: Zinc polyphosphate glasses were examined as potential candidates for low temperature sealing applications. Glass-formation and properties were determined for the ZnO-P{sub 2}O{sub 5}, ZnO-B{sub 2}O{sub 3}-P{sub 2}O{sub 5} and ZnO-SnO-P{sub 2}O{sub 5} systems, and information about the short-range structures of these glasses was obtained by Raman and solid state nuclear magnetic resonance spectroscopies. In general, the most durable polyphosphate glasses have structures based on relatively short pyrophosphate chain lengths (i.e., 2 P-tetrahedra). Modified phosphate compositions are given, including compositions used to seal float glass substrates at temperatures as low as 500{degrees}C.
Date: October 1, 1997
Creator: Brow, R.K.; Bencoe, D.N. & Tallant, D.R.
Partner: UNT Libraries Government Documents Department

In situ X-Ray Absorption Spectro-Electrochemical Study of Amorphous Tin-Based Composite Oxide Material

Description: We have measured the XAFS spectra of a sample of tin-based composite oxide (TCO) material with a nominal composition of Sn{sub 1.0}B{sub 0.56}P{sub 0.40}Al{sub 0.42}O{sub 3.47} during the discharge and charge cycles in an ''in situ'' configuration. Our results confirm the amorphous nature of TCO and show that Sn in TCO is coordinated with 3 oxygen atoms at a distance of 2.12 {angstrom}. Upon discharging, initially, Li interacts with the electrochemically active Sn-O center forming metallic Sn in the form of clusters containing just a few atoms. Upon further discharge, Li alloys with Sn forming initially highly dispersed forms of Li{sub 2}Sn{sub 5} and/or LiSn and then Li{sub 7}Sn{sub 3}, Li{sub 5}Sn{sub 2}, Li{sub 13}Sn{sub 5}, or Li{sub 7}Sn{sub 2}. The true nature of the formed alloys could be significantly different from that of the corresponding crystalline phases. Upon charging, metallic Sn is produced with a Sn-Sn distance intermediate to those of gray and white Sn.
Date: November 1, 1998
Creator: Mansour, A. N.; Mukerjee, S.; Yang, X. Q. & McBreen, J.
Partner: UNT Libraries Government Documents Department

Corrosion of AISI Type 304 Stainless Steel in High Temperature Borated Water

Description: BS>The corrosion of type 304 stainless steel in water containing boric acid at 600 deg F and 2000 psig and at a flowvelocity of seven feet per second was investigated as a function of boron concentration and of alkaliknity. At a boron concentration of 39 ppm and at a pH value of 10, controlled with lithium hydroxide, no trend of corrosive attack with time was found after the first tw0 days. At a concentration of 41 ppm boron wlth no pH control (pH = 6.9), a regression tyoe equation of the form Y= A + B log (t), was found to express the relationship between corrosive attack and exposure teme. A similiar relationship was found at 1600 ppm boron withthe pH value maintained at 10 using lithium hydroxide. No evidence of raicrostructural attack was observed on coupon specimens under any of the conditions tested. The effects of surface finish and of position were studied. The effect of orientation of the rolling directon of coupon specimens with respect to the direction of fluid flow was also investigsted. (auth)
Date: December 1, 1958
Creator: Krieg, A. & Cytron, S. J.
Partner: UNT Libraries Government Documents Department

High-energy ion processing of materials for improved hardcoatings

Description: Research has been directed toward use of economically viable ion processing strategies for production and improvement of hardcoatings. Processing techniques were high-energy ion implantation and electron cyclotron resonance microwave plasma processing. Subject materials were boron suboxides, Ti-6Al-4V alloy, CoCrMo alloy (a Stellite{trademark}), and electroplated Cr. These materials may be regarded either as coatings themselves (which might be deposited by thermal spraying, plasma processing, etc.) or in some cases, as substrates whose surfaces can be improved. hardness and other properties in relation to process variables are reported.
Date: February 1, 1994
Creator: Williams, J.M.; Gorbatkin, S.M.; Rhoades, R.L.; Oliver, W.C.; Riester, L. & Tsui, T.Y.
Partner: UNT Libraries Government Documents Department


Description: The diffusion length of thermal neutrons in light water was measured as a function of temperature in the range 20 to 90 un. Concent 85% C for both pure water and poison solutions. Various concertrations of three poisons and up to st r H/sub 3/BO/sub 3/, CdSO/sub 4/, and Gd(NO/sub 3/)/sub 3/--were used in this experiment. The thermal neutron source was the thermal column of the General Electric Nuclear Test Reactor. The Water Gun'' apparatus was utilized for the measurements. (auth)
Date: April 1, 1962
Creator: Russell, J.L. Jr.; Ballowe, W.C.; Morgan, W.R. & Mosgovoy, W.V.
Partner: UNT Libraries Government Documents Department