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THE EFFECT OF MAGNETICALLY ALIGNED POWDER ON THE MAGNETOSTRICTION OF SINTERED RARE EARTH-IRON LAVES PHASE COMPOUNDS

Description: A powder metallurgical approach is utilized to prepare grain oriented Laves phase compounds of Tb{sub x}Dy{sub 1-x}Fe{sub 2}. The magnetostrains observed in the oriented compounds, though containing {approx}20% porosity as presently prepared, are far superior to those of arc cast and highly dense liquid phase sintered materials. Also, it is shown that the alignment achieved is strongly dependent on the Tb/Dy ratio.
Date: October 1, 1977
Creator: Malekzadeh, M. & Pickus, M.R.
Partner: UNT Libraries Government Documents Department

Gelcasting of silicon preforms for the production of sintered reaction-bonded silicon nitride

Description: Gelcasting of silicon metal for the production of sintered reaction-bonded silicon nitride (SRBSN) was investigated in order to identify associated advantages over conventional forming techniques, i.e., die and isostatic pressing. Compacts were formed from identical powder mixtures by both gelcasting and pressing, and were nitrided and sintered to produce SRBSN ceramics using both conventional and microwave heating. Characterization of the samples included measurement of green density, green and nitrided pore structure, weight gain during nitridation, final density, microstructure, toughness, and flexural strength. It was found that a more uniform pore structure existed in the green gelcast samples. It is believed that this pore configuration aided in nitridation, and manifested itself in a more uniform final microstructure. In addition, improved mechanical properties were achieved in the gelcast samples. This improvement can be attributed to green microstructure homogeneity. An additional finding of this study was that microwave hearing combined with gelcast forming resulted in SRBSN materials with improved mechanical properties.
Date: December 1995
Creator: Kiggans, J. O., Jr.; Nunn, S. D.; Tiegs, T. N.; Davisson, C. C.; Coffey, D. W. & Maria, J.P.
Partner: UNT Libraries Government Documents Department

Fabrication and Properties of Seamless Tungsten Tubing

Description: A process for the production of seamless tungsten tubing is described. The process consists of the extrusion of sintered powder sleeves at elevated temperatures to sizes close to the final dimension. The tubing is finished by warm drawing. A size range of 0.100-in, diameter to 1 1/2-in. diameter has been fabricated. A preliminary evaluation of properties of the extruded tubes is given. (auth)
Date: October 31, 1964
Creator: Loewenstein, P.; Hunt, J. G. & Jenkins, R. G.
Partner: UNT Libraries Government Documents Department

A STUDY OF THE EFFECTS OF FABRICATING CONDITIONS ON SOME PROPERTIES OF SINTERED URANIUM MONOCARBIDE

Description: The effect of initial particle size (6.2 and 14.7 mu ), forming pressure (50,000 and 100,000 psi), temperature (1600 and 1800 deg C), and time at temperature (1 and 3 hr) on the bulk density, grain size, and porosity of sintered uranium monocarbide compacts was studied, Within the limits of the variables studied there appeared to be no significant changes in these properties of the sintered material attributable to the changes in the fabricating conditions. (auth)
Date: October 1, 1959
Creator: Tripler, A.B. Jr.; Snyder, M.J. & Duckworth, W.H.
Partner: UNT Libraries Government Documents Department

THE EFFECT OF MAGNETICALLY ALIGNED POWDER ON THE MAGNETOSTRICTION OF SINTERED RARE EARTH - IRON LAVES PHASE COMPOUNDS

Description: A powder metallurgical approach is utilized to prepare grain oriented Laves phase compounds of Tb{sub x}Dy{sub 1-x}Fe{sub 2}. The magnetostrains observed in the oriented compounds, though containing {approx}20% porosity as presently prepared, are far superior to those of arc cast and highly dense liquid phase sintered materials. Also, it is shown that the alignment achieved is strongly dependent on the Tb/Dy ratio.
Date: October 1, 1977
Creator: Malekzadeh, M. & Pickus, M.R.
Partner: UNT Libraries Government Documents Department

Thermomechanical Response of Layered Materials. Final technical report

Description: A new experimental technique involving instrumented indentation was demonstrated for the specific purpose of calibrating certain variations in elastic properties as a function of position in thermally sprayed and sintered materials. This work experimentally demonstrated for the first time that controlled gradients in elastic properties alone can lead to the suppression of damage and cracking during contact loading. New methods were developed in this work for the estimation of mechanical properties of ductile alloys and brittle ceramics by recourse to continuous measurements of load-penetration curves with spherical microindenters.
Date: May 20, 2000
Creator: Suresh, S.
Partner: UNT Libraries Government Documents Department

CHARACTERIZATION OF UO$sub 2$ POWDERS. Fourth Quarterly Report, July 10, 1961-October 10, 1961

Description: Studies are described of UO/sub 2/ powders to determine the relation between properties of the powders and sinterability. The main effort during the period was devoted to correlation of the powder particle size distribution with the sintered density of pellets. The pressure applied during the green forming step of pellet production is shown to have a varied and considerable effect on ceramic particle size distribution in the pellets. (J.R.D.)
Date: January 20, 1962
Creator: Carpenter, J.F.; Kuhlman, C.W. & Nelson, R.A.
Partner: UNT Libraries Government Documents Department

Effects of coal slag corrosion on the mechanical properties of sintered {alpha}-silicon carbide

Description: Tubes of sintered SiC were exposed for 500 h in a laboratory furnace to three different coal slags at three temperatures. No corrosive attack or strength reduction was observed after exposure at 1090{degrees}C. At 1260{degrees}C the least viscous slag caused formation of corrosion pits and loss of strength. At 1430{degrees}C formation of iron silicides at the interface between the slag and the base material caused severe loss of strength for slags with the highest and the lowest viscosity, while the specimens exposed to the slag with medium viscosity and medium iron content survived quite well. The results show that mechanical strength can be retained for certain coal slag - temperature combinations.
Date: March 1, 1997
Creator: Hannel, S.E.; Breder, K. & Joslin, D.L.
Partner: UNT Libraries Government Documents Department

Lightweight alumina refractory aggregate. Final report

Description: Objective was to develop a lightweight, high alumina refractory aggregate for use in various high performance insulating (low thermal conductivity) refractory applications (e.g., in the aluminium, glass, cement, and iron and steel industries). A new aggregate process was developed through bench and pilot-scale experiments involving extrusion of a blend of calcined and activated alumina powders and organic extrusion aids and binders. The aggregate, with a bulk density approaching 2.5 g/cc, exhibited reduced thermal conductivity and adequate fired strength compared to dense tabular aggregate. Refractory manufacturers were moderately enthusiastic over the results. Alcoa prepared an economic analysis for producing lightweight aggregate, based on a retrofit of this process into existing Alcoa production facilities. However, a new, competing lightweight aggregate material was developed by another company; this material (Plasmal{trademark})had a significantly more favorable cost base than the Alcoa/DOE material, due to cheap raw materials and fewer processing steps. In late 1995, Alcoa became a distributor of Plasmal. Alcoa estimated that {ge}75% of the market originally envisioned for the Alcoa/DOE aggregate would be taken by Plasmal. Hence, it was decided to terminate the contract without the full- scale demonstration.
Date: July 16, 1996
Creator: Swansiger, T.G. & Pearson, A.
Partner: UNT Libraries Government Documents Department

Fabrication and texture characterization of bulk (Bi,Pb){sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub x} and Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub x} superconductors

Description: Bulk (Bi,Pb){sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub x} (Bi-2223) and Bi{sub 2}Sr{sub 2}CaCU{sub 2}0{sub x} (Bi-2212) superconductors were fabricated by sinter forging. Bi-2223 ({approx}90% Bi-2223, 10% (Bi,Pb){sub 2}Sr{sub 2}CaCU{sub 2}0. + other phases) and Bi-2212 (nearly phase pure) powders were first synthesized and then cold pressed into bars that were -50% dense. These bars were surrounded by Ag foil, heated in air to {approx}845{degrees}C, and compressed for 3--6 h. The resultant bars were dense and highly textured. At 77 K, the Bi-2223 exhibited transport critical current density (J{sub c}) values of 2000--8000 A/cm{sup 2}; the Bi-2212 exhibited very low J{sub c}. Extent of texture was evaluated by three X-ray diffraction methods: 2{theta} scans, rocking curves, and orientation distribution functions. It was found that J{sub c} correlated best with the orientation distribution functions.
Date: May 1, 1995
Creator: Goretta, K.C.; Chen, Nan; Biondo, A.C.; Fisher, B.L.; Lanagan, M.T. & Kallend, J.S.
Partner: UNT Libraries Government Documents Department

Comparison of properties of sintered and sintered reaction-bonded silicon nitride fabricated by microwave and conventional heating

Description: A comparison of microwave and conventional processing of silicon nitride-based ceramics was performed to identify any differences between the two, such as improved fabrication parameters or increased mechanical properties. Two areas of thermal processing were examined: sintered silicon nitride (SSN) and sintered reaction-bonded silicon nitride (SRBSN). The SSN powder compacts showed improved densification and enhanced grain growth. SRBSN materials were fabricated in the microwave with a one-step process using cost-effective raw materials. The SRBSN materials had properties appropriate for structural applications. Observed increases in fracture toughness for the microwave processed SRBSN materials were attributable to enhanced elongated grain growth.
Date: October 1, 1995
Creator: Tiegs, T.N.; Kiggans, J.O. Jr. & Lin, H.T. and others
Partner: UNT Libraries Government Documents Department

DISPERSION-STRENGTHENED VANADIUM ALLOYS. Bimonthly Report No. 1, December 14, 1962-February 13, 1963

Description: Dispersion-strengthening mechanisms are under investigation in alloys based on the Nb-- V system for the purpose of improving stress-rupture properties. Ten compositions containing small C additions in combination with Hf or Zr were prepared by nonconsumable-electrode arc melting. Powder metallurgy preparation of alloys containing dispersed refractory particles is also under investigation. Minus 325 mesh powders of a V--Nb--Ti alloy were produced by the hydride process; the sintered compacts were over 90% of theoretical density and possessed a relatively high degree of compressive ductility at room temperature. (auth)
Date: March 12, 1963
Creator: Holtz, F.C.
Partner: UNT Libraries Government Documents Department

PROGRESS IN THE DEVELOPMENT OF A PROCESS FOR PRODUCING UO$sub 2$ PELLETS

Description: Progress in the development of manufacturing procedures and techniques for uranium dioxide fuel pellets is described. Specifications for both the uranium oxide powder and the final fuel pellet are given. A process is described for making pellets wlth closely controlled density, dimensions, purity, and freedom from structural defects from ADU (ammonium diurante process) uranium dioxide powder. A formula relating lineaashrinkage to green and fired densitles has been derived, This formula has proven a useful tool in control of fired or slnterod pellet dimensions and densities esses described were utillzod in the manufacture of pellets for use in critical experiments. Improvements in processlng continue to be developed. (auth)
Date: December 1, 1958
Creator: Winchell, R.
Partner: UNT Libraries Government Documents Department

THE BORON-CARBON SYSTEM. Final Technical Report, May 1, 1960-April 30, 1961

Description: The boron--carbon equilibrium diagram was determined by x-ray, metallographic, and thermal analysis of sintered and arc-cast alloys. A single carbide having a range of solubility from approximately 9 to 20 at.% carbon and melting congruently exists in the system. The terminal solubility of carbon in boron is 0.1-0.2 at.%. The freezing reaction between boron and the carbide is a degenerate peritectic --eutectic reaction at the composition and melting temperature of elemental boron; there is a eutectic reaction at 29 at.% carbon and 2375 deg C. No allotropy of boron was observed. (auth)
Date: June 1, 1961
Creator: Elliott, R.P.
Partner: UNT Libraries Government Documents Department

Investigation of wear resistant material using dispersed phase intermetallic compound of nickel--titanium--silicon in an iron matrix

Description: The physical and mechanical properties of iron powder blended with a hard intermetallic compound, Ni/sub 3/Ti/sub 2/Si, were studied in the as-sintered condition. The influence of the morphology on the wear tests was investigated using a pin-on-disk wear test machine. The variables affecting the morphology of this system have been experimentally determined.
Date: December 1, 1977
Creator: Steinmetz, C.
Partner: UNT Libraries Government Documents Department

THORIUM OXIDE SLURRY FILTRATION: PRELIMINARY TESTS OF A 3-MICRON POROLOY SINTERED FILTER RUNS 11, 12 AND 13 IN LOOP L-4-24S

Description: A Poroloy sintered-metal filter unit which was placed in a bpass arrangement in a 5-gpm loop, L-4-24S, for runs 11 and 12 was used to separate water from a flowing stream of thoria slurry. During runs ll and l2, the filter unit prevented the accumulation of thoria in the horizontal pressurizer during 490 hr of operation at temperatures up to 250 deg C and circulating stream concentrations up to 490 g Th/kg H/sub 2/0. Run 13 was made with the main stream of the loop flowing through the center of the filter. The flow velocity through the center of the filter was sufficiently high to prevent a filter cake from building up, and consequently, the filter unit was rendered ineffective. Microscopic examination of the filter screen revealed no other reason for the ineffectiveness of the filter in run 13 other than the lack of filter cake. Further testing with and without cake buildup is scheduled for work in the pump test stand and in L-4-24S. (auth)
Date: January 1, 1959
Creator: Jones, D.T. & Baker, J.M.
Partner: UNT Libraries Government Documents Department

Heavy Water Power Reactor Program Monthly Progress Report, October 1963

Description: Research and development progress is reported on the AEC-AECL cooperative program, CANDU Reactor development, creep-rupture properties of SAP, heat transfer and fluid flow studies, zirconium technology, metallurgy, Savannah River Componente Test Reactor operation, reactor fuel elements development, Carolinas-Virginia Tube Reactor development and operation, and power reactor technology.
Date: October 31, 1964
Partner: UNT Libraries Government Documents Department

MANUFACTURE OF THE ThO$sub 2$-UO$sub 2$ CERAMIC FUEL PELLETS FOR BORAX-IV

Description: Preliminary investigation indicated that it was possible to prepare thoria-urania solid solutions by sintering in air a mixture of ThO/sub 2/ and U/ sub 3/O.sub 8/. The U/sub 3/O/sub 8/ on heatin g in air was found to disassociate, and when heated with ThO/sub 2/, the resultant body was essentially a ThO/sub 2/-UO/sub 2/ solid solution. The methods used in preparing and granulating the ThO/sub 2/ and U/sub 3/O/sub 8/ for the BORAX-IV loading are discussed in detail. This material was dry pressed using pressures from 13,000 to 15,000 psi. The pressed pellets were loaded into alumina crucibles and fired to a peak temperature of 1700 deg C to 1750 deg C. The fired ware was found to have an average ap parent density of 9.8 g/cc. The pellets were loaded into Al1 wt.% Ni tube plates and the annulus between the pellet and the tube was filled with lead. After closing the open end of the tube plates, the plates were spot welded into a subassembly. (auth)
Date: August 1, 1957
Creator: Handwerk, J.H.; Hoenig, C.L. & Lied, R.C.
Partner: UNT Libraries Government Documents Department

HYDROGEN FLAMMABILITY DATA AND APPLICATION TO PWR LOSS-OF-COOLANT ACCIDENT

Description: Supplemental to WAPD-SC-54l. A summary is presented of generalized data on the flammability of hydrogen in steam-air mixtures. The flammability data are applied to a postulated Pressurized Water Reactor loss-of-coolant accident and to estimates of the potential pressure effects on the PWR plant container. (C.H.)
Date: September 1, 1957
Creator: Shapiro, Z.M. & Moffette, T.R.
Partner: UNT Libraries Government Documents Department