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Chemical Research Section Progress Report for January 1950

Description: The following documents are progress reports that follow chemical research studies in subjects such as ruthenium tetroxile distillations, extraction-scrub studies of zirconium and niobium, and oxidation of plutonium and stabilization of plutonium(VI) during extraction of IAF solutions.
Date: February 15, 1950
Creator: Albaugh, F. W.
Partner: UNT Libraries Government Documents Department

Transient-Liquid-Phase and Liquid-Film-Assisted Joining ofCeramics

Description: Two joining methods, transient-liquid-phase (TLP) joining and liquid-film-assisted joining (LFAJ), have been used to bond alumina ceramics. Both methods rely on multilayer metallic interlayers designed to form thin liquid films at reduced temperatures. The liquid films either disappear by interdiffusion (TLP) or promote ceramic/metal interface formation and concurrent dewetting of the liquid film (LFAJ). Progress on extending the TLP method to lower temperatures by combining low-melting-point (<450 C) liquids and commercial reactive-metal brazes is described. Recent LFAJ work on joining alumina to niobium using copper films is presented.
Date: February 9, 2005
Creator: Sugar, Joshua D.; McKeown, Joseph T.; Akashi, Takaya; Hong, SungM.; Nakashima, Kunihiko & Glaeser, Andreas M.
Partner: UNT Libraries Government Documents Department

THE SELF-DIFFUSION OF NIOBIUM--I. First Annual Progress Report, January 1, 1956 to June 30, 1957

Description: The measurement of the self-diffusion coefficient of niobium as a function of temperature has been undertaken. It is planned to prepare the diffusion couples by the deposition of Nb/sup 95/ onto the surfaces of niobium discs from the Nb/sup 95/Cl/sub 5/ vapor phase and to anneal the couples in the temperature range 1600 deg to 2000 deg K. Details are given of the construction of the vapor deposition apparatus and of the preparation of Nb/sup 95/Cl/sub 5/ from the oxalate form in which the isotope is received. Preliminary measurements of the diffusion coefficient in a Nb-8 wt.% Ti alloy and In a Nb-1.4 wt.% V alloy indicate that the diffusion coefficient in the former is approximately 10/sup -9/ cm/sup 2//sec at 1600 deg C and is approximately 8 x 10/sup -11/ cm/sup 2//sec in the latter at 1400 deg C. (auth)
Date: February 1, 1958
Creator: Resnick, R.; Castleman, L.S. & Seigle, L.
Partner: UNT Libraries Government Documents Department

Half-Wave, beta=0.43 Cavity Prototyping for a Heavy Ion Linac

Description: A medium velocity half wave resonator has been designed and prototyped at the National Superconducting Cyclotron Laboratory (NSCL) at Michigan State University (MSU) for use in a heavy ion linac. The cavity is designed to provide 3.7 MV of accelerating voltage at an optimum beta = v/c = 0.53, with peak surface electric and magnetic fields of 32.5 MV/m and 79 mT, respectively. The cavity was designed for stiffness and tunability, as well as straightforward fabrication, assembly and cleaning. Measurements were performed to confirm Finite Element Analysis (FEA) predictions for modal analysis, bath pressure sensitivity, tuner stiffness and tuning range. A copper cavity prototype has been fabricated to confirm tolerances and formability. A tuner prototype has been built. The helium vessel and power coupler have been designed.
Date: April 1, 2008
Creator: Popielarski, John; Compton, Chris C.; Hartung, Walter; Johnson, Mat; Oliva, John; York, R. C. et al.
Partner: UNT Libraries Government Documents Department

Research and development for electropolishing of Nb for ILC accelerator cavities

Description: The objectives of this project are to 1, Expand the scientific and technological understanding of the effect of post-treatment (electropolish, buffered chemical polish, low-temperature baking) on the surface of niobium; 2, Relate the knowledge to the performance of niobium superconducting radiofrequency accelerator cavities; and, 3, Thereby design and demonstrate an electropolish process that can be applied to complete cavities.
Date: September 21, 2009
Creator: Kelley, Michael J.
Partner: UNT Libraries Government Documents Department

FLUIDIZED-BED COATING OF UO$sub 2$ POWDER WITH NIOBIUM AND OTHER ELEMENTS

Description: The chemical vapor deposition of niobium, molybdenum, tungsten, chnomium, carbcn, and niobium--vanadium alloys in a fluidized bed of UO/sub 2/ powder particles wss used to provide uniform, dense, nonporous coatings on the individual particles. in the case of niobium, which received major attention, hydrogen reduction of niobium pentachloride vapor was used as the vapor- deposition reaction. The most serious problem was that of maintaining bed fluidity aad avoiding agglomeration. This problem was overcome to permit routine operation of the coating equipment. In the entire program of 68 experimental runs, only 1.1 per cent of the product was lost by agglomeration. In routine operation, this loss should be even lower. (auth)
Date: May 25, 1960
Creator: Blocher, J.M. Jr.; Veigel, N.D.; Oxley, J.H.; Secrest, V.M. & Rose, E.E.
Partner: UNT Libraries Government Documents Department

A REVIEW OF THE EXTRACTIVE METALLURGY OF NIOBIUM

Description: BS>The preparation of niobium was attempted by a number of chemical and electrochemical routes. Chemical reduction of oxides and halides such as Nb/sub 2/O/sub 5/, K/sub 2/NbOF/sub 5/, K/sub 2/NbF/sub 7/, and NbCl/sub 5/ was conducted with varying degrees of success. Aqueous electrochemical reduction has not yet yielded a metallic deposit. The electrolysis of molten baths containing K/sub 2/NbOF/sub 5/ or K/sub 2/NbF/sub 7/ produced niobium metal. The more promising methods of preparation for Nb metal at the present time include the reaction of Nb/sub 2/O/sub 5/ with C, the H/sub 2/ and active metal reduction of NbC1/sub 5/, and electrolysis of K/sub 2/NbF/sub 7/- NaC1 melts. (auth)
Date: January 1, 1950
Creator: Sibert, M. E.; Kolk, A. J., Jr. & Steinberg, M. A.
Partner: UNT Libraries Government Documents Department

THE SELF-DIFFUSION OF NIOBIUM--II. Second Annual Progress Report, July 1, 1957 to June 30, 1958

Description: The self-diffusion coefficient of niobium was measured as a function of temperature. Procedures were developed for the preparation of NbCl/sub 5/ from a solution of radioactive Nb/sup 95/ in oxalic acid, and the subsequent vapor plating of a radioactive metallic layer from this volatile compound. Initial measurements made at 2000 and 1800 deg C yield values for the self-diffusion coefficient of 3.2 x 10/sup -9/ cm/sup 2/sec and 1.7 x 10/sup 10/ cm/sup 2/sec, respectively. (auth)
Date: June 30, 1958
Creator: Resnick, R.; Castleman, L.S. & Seigle, L.
Partner: UNT Libraries Government Documents Department

NIOBIUM CARBIDE COATING OF GRAPHITE TUBES

Description: Graphite tubes having a length-to-bore-diameter ratio of 430 were coated on the inside with uniform adherent layers of niobium carbide in thicknesses of 0.002 and 0.004 in. Intimate conformity to the graphite surface and improved uniformity were obtained by reacting NbCl/sub 5/ vapor with the graphite under pressuretemperature conditions thermodynamically unfavorable for the deposition of niobium by thermal dissociation of the chloride, but favorable for the formation of NbC. Thus, the rate of coating fermation depended primarily on the rate of diffusion of carbon through the carbide, which is a function of temperature and independent of vapor-flow considerations over a wide range, Although adherent coatings were obtained on a porous uraniumloaded graphite in the as-received condition, it was necessary to etch a more dense graphite to promote adherence. (auth)
Date: October 1, 1958
Creator: Blocher, J.M. Jr.; Browning, M.F.; Leiter, D.P. Jr. & Campbell, I.E.
Partner: UNT Libraries Government Documents Department

Progress of ILC High Gradient SRF Cavity R&D at Jefferson Lab

Description: Latest progress of ILC high gradient SRF cavity R&D at Jefferson Lab will be presented. 9 out of 10 real 9-cell cavities reached an accelerating gradient of more than 38 MV/m at a unloaded quality factor of more than 8 {center_dot} 109. New understandings of quench limitation in 9-cell cavities are obtained through instrumented studies of cavities at cryogenic temperatures. Our data have shown that present limit reached in 9-cell cavities is predominantly due to localized defects, suggesting that the fundamental material limit of niobium is not yet reached in 9-cell cavities and further gradient improvement is still possible. Some examples of quench-causing defects will be given. Possible solutions to pushing toward the fundamental limit will be described.
Date: September 1, 2011
Creator: R.L. Geng, J. Dai, G.V. Eremeev, A.D. Palczewski
Partner: UNT Libraries Government Documents Department