Sample records for powder metallurgy compacts

  1. Electrothermal Defect Detection in Powder Metallurgy Compacts

    NASA Astrophysics Data System (ADS)

    Benzerrouk, Souheil; Ludwig, Reinhold; Apelian, Diran

    2006-03-01

    Faced with increasing market pressures, metal part manufacturers have turned to new processes and fabrication technologies. One of these processes is powder metallurgy (P/M), which is employed for low-cost, high-volume precision part manufacturing. Despite many advantages, the P/M process has created a number of challenges, including the need for high-speed quality assessment and control, ideally for each compact. Consequently, sophisticated quality assurance is needed to rapidly detect flaws early in the manufacturing cycle and at minimal cost. In this paper we will discuss our progress made in designing and refining an active infrared (IR) detection system for P/M compacts. After discussing the theoretical background in terms of underlying equations and boundary conditions, analytical and numerical solutions are presented that are capable of predicting temperature responses for various defect sizes and orientations of a dynamic IR testing system. Preliminary measurements with controlled and industrial samples have shown that this active IR methodology can successfully be employed to test both green-state and sintered P/M compacts. The developed system can overcome many limitations observed with a standard IR testing methodology such as emissivity, background calibration, and contact resistance.

  2. Workability in forging of powder metallurgy compacts

    Microsoft Academic Search

    M. Abdel-Rahman; M. N. El-Sheikh

    1995-01-01

    The power metallurgy (PM) technique is now applied widely to many industries and materials. To obtain more reliable PM products, many secondary processes are applied to PM preforms. The problem of deformation and fracture of PM preforms still needs a considerable amount of investigation.In this work, the effect of the relative density on the forming limit of PM compacts in

  3. Effect of die wall lubrication on warm compaction powder metallurgy

    Microsoft Academic Search

    Y. Y Li; T. L Ngai; D. T Zhang; Y Long; W Xia

    2002-01-01

    Die wall lubrication was applied on warm compaction powder metallurgy in the hope to reduce the concentration level of the admixed lubricant, since lubricant is harmful to the mechanical properties of the sintered material. Iron-based samples were prepared by die wall lubricated warm compaction at 135 and 175°C, using polytetrafluoroethylene (PTFE) emulsion as the die wall lubricant. Compacting pressures of

  4. Acoustic harmonic generation measurement applications: Detection of tight cracks in powder metallurgy compacts

    NASA Astrophysics Data System (ADS)

    Barnard, D. J.; Foley, J. C.

    2000-05-01

    Standard linear ultrasonic testing techniques have long been employed for locating and characterizing relatively open cracks in a wide variety of materials, from metallic alloys and ceramics to composites. In all these materials, the detection of open cracks easily accomplished because the void between the two crack surfaces provides sufficient acoustic impedance mismatch to reflect the incident energy. Closed or partially closed cracks, however, may often go undetected because contacting interfaces allow transmission of ultrasound. In the green (unsintered) state, powder metallurgy compacts typically contain high residual stresses that have the ability to close cracks formed during the compaction process, a result of oxide films, improper powder lubricant, mold design, etc. After sintering, the reduction of residual stresses may no longer be sufficient to close the crack. Although the crack may be more easily detected, it is obvious most desirable to discover defects prior to sintering. It has been shown that the displacements of an interface may be highly nonlinear if a stress wave of sufficient intensity propagates across it, a result of the stress wave either opening or closing the interface. Current efforts involve the application of nonlinear acoustic techniques, in particular acoustic harmonic generation measurements, for the detection and characterization of tightly closed cracks in powder metallurgy parts. A description of the equipment and the measurement technique will be discussed and initial experimental results on sintered and green compacts will be presented.—This work was performed at the Ames Laboratory, Iowa State University under USDOE Contract No. W-7405-ENG-82.

  5. Active Thermography for the Detection of Defects in Powder Metallurgy Compacts

    NASA Astrophysics Data System (ADS)

    Benzerrouk, Souheil; Ludwig, Reinhold; Apelian, Diran

    2007-03-01

    Active thermography is an established NDE technique that has become the method of choice in many industrial applications which require non-contact access to the parts under test. Unfortunately, when conducting on-line infrared (IR) inspection of powder metallic compacts, complications can arise due the generally low emissivity of metals and the thermally noisy environment typically encountered in manufacturing plants. In this paper we present results of an investigation that explores the suitability of active IR imaging of powder metallurgy compacts for the detection of surface and sub-surface defects in the pre-sinter state and in an on-line manufacturing setting to ensure complete quality assurance. Additional off-line tests can be carried out for statistical quality analyses. In this research, the IR imaging of sub-surface defects is based on a transient instrumentation approach that relies on an electric control system which synchronizes and monitors the thermal response due to an electrically generated heat source. Preliminary testing reveals that this newly developed pulsed thermography system can be employed for the detection of subsurface defects in green-state parts. Practical measurements agree well with theoretical predictions. The inspection approach being developed can be used for the testing of green-state compacts as they exit the compaction press at speeds of up to 1,000 parts per hour.

  6. Biaxially textured articles formed by powder metallurgy

    DOEpatents

    Goyal, Amit; Williams, Robert K.; Kroeger, Donald M.

    2003-08-05

    A biaxially textured alloy article having a magnetism less than pure Ni includes a rolled and annealed compacted and sintered powder-metallurgy preform article, the preform article having been formed from a powder mixture selected from the group of ternary mixtures consisting of: Ni powder, Cu powder, and Al powder, Ni powder, Cr powder, and Al powder; Ni powder, W powder and Al powder; Ni powder, V powder, and Al powder; Ni powder, Mo powder, and Al powder; the article having a fine and homogeneous grain structure; and having a dominant cube oriented {100}<100> orientation texture; and further having a Curie temperature less than that of pure Ni.

  7. Biaxially textured articles formed by powder metallurgy

    DOEpatents

    Goyal, Amit; Williams, Robert K.; Kroeger, Donald M.

    2003-08-19

    A biaxially textured alloy article having a magnetism less than pure Ni includes a rolled and annealed compacted and sintered powder-metallurgy preform article, the preform article having been formed from a powder mixture selected from the group of mixtures consisting of: at least 60 at % Ni powder and at least one of Cr powder, W powder, V powder, Mo powder, Cu powder, Al powder, Ce powder, YSZ powder, Y powder, Mg powder, and RE powder; the article having a fine and homogeneous grain structure; and having a dominant cube oriented {100}<100> orientation texture; and further having a Curie temperature less than that of pure Ni.

  8. Biaxially textured articles formed by powder metallurgy

    DOEpatents

    Goyal, Amit; Williams, Robert K.; Kroeger, Donald M.

    2003-08-26

    A biaxially textured alloy article having a magnetism less than pure Ni includes a rolled and annealed compacted and sintered powder-metallurgy preform article, the preform article having been formed from a powder mixture selected from the group of mixtures consisting of: at least 60 at % Ni powder and at least one of Cr powder, W powder, V powder, Mo powder, Cu powder, Al powder, Ce powder, YSZ powder, Y powder, Mg powder, and RE powder; the article having a fine and homogeneous grain structure; and having a dominant cube oriented {100}<100> orientation texture; and further having a Curie temperature less than that of pure Ni.

  9. Biaxially textured articles formed by powder metallurgy

    DOEpatents

    Goyal, Amit; Williams, Robert K.; Kroeger, Donald M.

    2005-01-25

    A biaxially textured alloy article having a magnetism less than pure Ni includes a rolled and annealed compacted and sintered powder-metallurgy preform article, the preform article having been formed from a powder mixture selected from the group of mixtures consisting of: at least 60 at % Ni powder and at least one of Cr powder, W powder, V powder, Mo powder, Cu powder, Al powder, Ce powder, YSZ powder, Y powder, Mg powder, and RE powder; the article having a fine and homogeneous grain structure; and having a dominant cube oriented {100}<100> orientation texture; and further having a Curie temperature less than that of pure Ni.

  10. Biaxially textured articles formed by powder metallurgy

    DOEpatents

    Goval, Amit; Williams, Robert K.; Kroeger, Donald M.

    2005-06-07

    A biaxially textured alloy article having a magnetism less than pure Ni includes a rolled and annealed compacted and sintered powder-metallurgy preform article, the preform article having been formed from a powder mixture selected from the group of mixtures consisting of: at least 60 at % Ni powder and at least one of Cr powder, W powder, V powder, Mo powder, Cu powder, Al powder, Ce powder, YSZ powder, Y powder, Mg powder, and RE powder; the article having a fine and homogeneous grain structure; and having a dominant cube oriented {100}<100> orientation texture; and further having a Curie temperature less than that of pure Ni.

  11. Biaxially textured articles formed by powder metallurgy

    DOEpatents

    Goyal, Amit; Williams, Robert K.; Kroeger, Donald M.

    2004-09-28

    A biaxially textured alloy article having a magnetism less than pure Ni includes a rolled and annealed compacted and sintered powder-metallurgy preform article, the preform article having been formed from a powder mixture selected from the group of mixtures consisting of: at least 60 at % Ni powder and at least one of Cr powder, W powder, V powder, Mo powder, Cu powder, Al powder, Ce powder, YSZ powder, Y powder, Mg powder, and RE powder; the article having a fine and homogeneous grain structure; and having a dominant cube oriented {100}<100> orientation texture; and further having a Curie temperature less than that of pure Ni.

  12. Biaxially textured articles formed by powder metallurgy

    DOEpatents

    Goyal, Amit; Williams, Robert K.; Kroeger, Donald M.

    2005-05-10

    A biaxially textured alloy article having a magnetism less than pure Ni includes a rolled and annealed compacted and sintered powder-metallurgy preform article, the preform article having been formed from a powder mixture selected from the group of mixtures consisting of at least 60 at % Ni powder and at least one of Cr powder, W powder, V powder, Mo powder, Cu powder, Al powder, Ce powder, YSZ powder, Y powder, Mg powder, and RE powder; the article having a fine and homogeneous grain structure; and having a dominant cube oriented {100}<100> orientation texture; and further having a Curie temperature less than that of pure Ni.

  13. Biaxially textured articles formed by powder metallurgy

    DOEpatents

    Goyal, Amit; Williams, Robert K.; Kroeger, Donald M.

    2003-07-29

    A biaxially textured alloy article having a magnetism less than pure Ni includes a rolled and annealed compacted and sintered powder-metallurgy preform article, the preform article having been formed from a powder mixture selected from the group of mixtures consisting of: at least 60 at % Ni powder and at least one of Cr powder, W powder, V powder, Mo powder, Cu powder, Al powder, Ce powder, YSZ powder, Y powder, Mg powder, and RE powder; the article having a fine and homogeneous grain structure; and having a dominant cube oriented {100}<100> orientation texture; and further having a Curie temperature less than that of pure Ni.

  14. Biaxially textured articles formed by powder metallurgy

    DOEpatents

    Goyal, Amit; Williams, Robert K.; Kroeger, Donald M.

    2004-09-14

    A biaxially textured alloy article having a magnetism less than pure Ni includes a rolled and annealed compacted and sintered powder-metallurgy preform article, the preform article having been formed from a powder mixture selected from the group of mixtures consisting of: at least 60 at % Ni powder and at least one of Cr powder, W powder, V powder, Mo powder, Cu powder, Al powder, Ce powder, YSZ powder, Y powder, Mg powder, and RE powder; the article having a fine and homogeneous grain structure; and having a dominant cube oriented {100}<100> orientation texture; and further having a Curie temperature less than that of pure Ni.

  15. Powder Metallurgy Composite Materials Strengthened with Fibers

    Microsoft Academic Search

    Suren G. Agbalyan

    2001-01-01

    The extrusion dynamics of high-strength powder metallurgy composite materials was studied. The extrusion parameters for porous compacts of copper fibers and Cu ? Mo composites were optimized. It was shown that orientation of fibers is possible only when they are sufficiently widely dispersed in the powder matrix and also when the fiber length is much greater than its diameter l

  16. Densification of powder metallurgy billets by a roll consolidation technique

    NASA Technical Reports Server (NTRS)

    Sellman, W. H.; Weinberger, W. R.

    1973-01-01

    Container design is used to convert partially densified powder metallurgy compacts into fully densified slabs in one processing step. Technique improves product yield, lowers costs and yields great flexibility in process scale-up. Technique is applicable to all types of fabricable metallic materials that are produced from powder metallurgy process.

  17. Aluminum powder metallurgy processing

    SciTech Connect

    Flumerfelt, J.F.

    1999-02-12

    The objective of this dissertation is to explore the hypothesis that there is a strong linkage between gas atomization processing conditions, as-atomized aluminum powder characteristics, and the consolidation methodology required to make components from aluminum powder. The hypothesis was tested with pure aluminum powders produced by commercial air atomization, commercial inert gas atomization, and gas atomization reaction synthesis (GARS). A comparison of the GARS aluminum powders with the commercial aluminum powders showed the former to exhibit superior powder characteristics. The powders were compared in terms of size and shape, bulk chemistry, surface oxide chemistry and structure, and oxide film thickness. Minimum explosive concentration measurements assessed the dependence of explosibility hazard on surface area, oxide film thickness, and gas atomization processing conditions. The GARS aluminum powders were exposed to different relative humidity levels, demonstrating the effect of atmospheric conditions on post-atomization processing conditions. The GARS aluminum powders were exposed to different relative humidity levels, demonstrating the effect of atmospheric conditions on post-atomization oxidation of aluminum powder. An Al-Ti-Y GARS alloy exposed in ambient air at different temperatures revealed the effect of reactive alloy elements on post-atomization powder oxidation. The pure aluminum powders were consolidated by two different routes, a conventional consolidation process for fabricating aerospace components with aluminum powder and a proposed alternative. The consolidation procedures were compared by evaluating the consolidated microstructures and the corresponding mechanical properties. A low temperature solid state sintering experiment demonstrated that tap densified GARS aluminum powders can form sintering necks between contacting powder particles, unlike the total resistance to sintering of commercial air atomization aluminum powder.

  18. Surface Integrity of C-40 Steel Processed with WC-Cu Powder Metallurgy Green Compact Tools in EDM

    Microsoft Academic Search

    P. K. Patowari; U. K. Mishra; P. Saha; P. K. Mishra

    2011-01-01

    Electric discharge machining (EDM) is an electrothermal process where recast layer on the machined surface and heat-affected (HAZ) zone just below the machined surface are common phenomena. Thus, the assessment of surface integrity in EDM is a very important task. In this study, an attempt was made to modify the surface integrity of C-40 steel in EDM. WC-Cu powder metallurgy

  19. Magnesium Powder Metallurgy: Process and Materials Opportunities

    NASA Astrophysics Data System (ADS)

    Bettles, Colleen J.

    2008-06-01

    The major efforts in magnesium alloy development for automotive applications have concentrated on creep resistant alloys produced by permanent mould and high-pressure die casting routes. While large components, such as crankcases, will never be produced by powder metallurgy, there are smaller components in and around the powertrain which could be fabricated from powder precursors. This article will explore the potential of some of the more recent powder compaction developments, and discuss the alloy development strategies that emerge for magnesium-based components as a consequence of these process developments. In particular, the viability of direct powder extrusion of semi-finished product, using conventional extrusion or equal channel angular processing, combined with T6 heat treatments, will be considered.

  20. Electro-thermographic detection of cracks in green-state powder metallurgy compacts

    NASA Astrophysics Data System (ADS)

    Ludwig, Reinhold; Makarov, Sergey

    2001-04-01

    In this paper we investigate the suitability of direct electric heating in an effort to conduct infrared NDE for various low conductivity metallic materials. Both DC and AC electric currents can be used to create the necessary Joule's power density in the metallic samples. Even low-conducting media such as composites and rubber can be thermally stimulated with high-frequency fields due to their high penetration depths. The reported research describes analytically and experimentally how this active electric heating approach can be utilized to conduct thermal NDE to characterize surface defects of green-state powder metal samples. The electric current is applied through two disk electrodes located on either side of the sample under test. An infrared camera subsequently records the transient thermal temperature profile, converts it into digital form, and displays the results as an image on a computer screen.

  1. Biaxially textured articles formed by powder metallurgy

    DOEpatents

    Goyal, Amit; Williams, Robert K.; Kroeger, Donald M.

    2003-10-21

    A strengthened, biaxially textured alloy article having a magnetism less than pure Ni includes a rolled and annealed, compacted and sintered powder-metallurgy preform article, the preform article having been formed from a powder mixture selected from the group of mixtures consisting of: Ni, Ag, Ag--Cu, Ag--Pd, Ni--Cu, Ni--V, Ni--Mo, Ni--Al, Ni--Cr--Al, Ni--W--Al, Ni--V--Al, Ni--Mo--Al, Ni--Cu--Al; and at least one fine metal oxide powder; the article having a grain size which is fine and homogeneous; and having a dominant cube oriented {100}<100> orientation texture; and further having a Curie temperature less than that of pure Ni.

  2. A major advance in powder metallurgy

    NASA Technical Reports Server (NTRS)

    Williams, Brian E.; Stiglich, Jacob J., Jr.; Kaplan, Richard B.; Tuffias, Robert H.

    1991-01-01

    Ultramet has developed a process which promises to significantly increase the mechanical properties of powder metallurgy (PM) parts. Current PM technology uses mixed powders of various constituents prior to compaction. The homogeneity and flaw distribution in PM parts depends on the uniformity of mixing and the maintenance of uniformity during compaction. Conventional PM fabrication processes typically result in non-uniform distribution of the matrix, flaw generation due to particle-particle contact when one of the constituents is a brittle material, and grain growth caused by high temperature, long duration compaction processes. Additionally, a significant amount of matrix material is usually necessary to fill voids and create 100 percent dense parts. In Ultramet's process, each individual particle is coated with the matrix material, and compaction is performed by solid state processing. In this program, Ultramet coated 12-micron tungsten particles with approximately 5 wt percent nickel/iron. After compaction, flexure strengths were measured 50 percent higher than those achieved in conventional liquid phase sintered parts (10 wt percent Ni/Fe). Further results and other material combinations are discussed.

  3. 1987 Annual Powder Metallurgy Conference, Dallas, TX, May 17-20, 1987, Proceedings

    Microsoft Academic Search

    C. L. Freeby; H. Hjort

    1987-01-01

    The papers presented in this volume provide an overview of the current status of the P\\/M technology. Topics discussed include low-temperature compaction of titanium alloys by rapid omnidirectional compaction (ROC); gravitational contributions to microstructural coarsening in liquid phase sintering; applications of powder metallurgy techniques to produce improved bearing elements for cryogenic aerospace engine turbopumps; and powder metallurgy techniques in the

  4. Powder-Metallurgy Process And Product

    NASA Technical Reports Server (NTRS)

    Paris, Henry G.

    1988-01-01

    Rapid-solidification processing yields alloys with improved properties. Study undertaken to extend favorable property combinations of I/M 2XXX alloys through recently developed technique of rapid-solidification processing using powder metallurgy(P/M). Rapid-solidification processing involves impingement of molten metal stream onto rapidly-spinning chill block or through gas medium using gas atomization technique.

  5. Advances in powder metallurgy of soft magnetic materials

    Microsoft Academic Search

    Christopher G. Oliver

    1995-01-01

    This paper discusses two new powder metallurgy processes that provide increased soft magnetic performance over conventional techniques. The first is a process involving elevated compaction temperatures which enable sintered densities of 7.59 g\\/cm3 for iron containing 0.35% by weight of phosphorus. Maximum permeabilities exceeding 6,000 with saturation inductions of 19,730 G are typical results utilizing this process. The second process

  6. Welding of a powder metallurgy uranium alloy

    Microsoft Academic Search

    R. K. Holbert; M. W. Doughty; G. M. Alexander-Morrison

    1989-01-01

    The interest at the Oak Ridge Y-12 Plant in powder metallurgy (P\\/M) uranium parts is due to the potential cost savings in the fabrication of the material, to achieving a more homogeneous product, and to the reduction of uranium scrap. The joining of P\\/M uranium-6 wt-% niobium (U-6Nb) alloys by the electron beam (EB) welding process results in weld porosity.

  7. Low-Cobalt Powder-Metallurgy Superalloy

    NASA Technical Reports Server (NTRS)

    Harf, F. H.

    1986-01-01

    Highly-stressed jet-engine parts made with less cobalt. Udimet 700* (or equivalent) is common nickel-based superalloy used in hot sections of jet engines for many years. This alloy, while normally used in wrought condition, also gas-atomized into prealloyed powder-metallurgy (PM) product. Product can be consolidated by hot isostatically pressing (HIPPM condition) and formed into parts such as turbine disk. Such jet-engine disks "see" both high stresses and temperatures to 1,400 degrees F (760 degrees C).

  8. Ti Multicomponent Alloy Bulks by Powder Metallurgy

    NASA Astrophysics Data System (ADS)

    Zhang, Kuibao; Wen, Guanjun; Dai, Hongchuan; Teng, Yuancheng; Li, Yuxiang

    2014-10-01

    In this study, CrCuFeMnMo0.5Ti multicomponent alloy bulks were prepared by powder metallurgy of mechanical alloying and sintering. A simple body-centered cubic (bcc) solid solution was prepared after 40 h ball milling of the raw CrCuFeMnMo0.5Ti metallic powder. Particles of the alloyed powder are in microsized structures, which are actually a soft agglomeration of lamellar grains with thicknesses less than 1 ?m. Meanwhile, the lamellar granules are consisted of nanosized grains under rigid cold welding. The 80-h ball-milled powder was consolidated by cold pressing and subsequent sintering at 800°C. The observed main phase in the consolidated sample after milling for 80 h is still a bcc solid solution. The solidified sample of 80-h ball-milled powder exhibits a Vickers hardness of 468 HV, which is much higher than 171 HV of the counterpart prepared from the raw metallic powder.

  9. Biaxially textured articles formed by powder metallurgy

    DOEpatents

    Goyal, Amit (Knoxville, TN); Williams, Robert K. (Knoxville, TN)

    2001-01-01

    A biaxially textured alloy article comprises Ni powder and at least one powder selected from the group consisting of Cr, W, V, Mo, Cu, Al, Ce, YSZ, Y, Rare Earths, (RE), MgO, CeO.sub.2, and Y.sub.2 O.sub.3 ; compacted and heat treated, then rapidly recrystallized to produce a biaxial texture on the article. In some embodiments the alloy article further comprises electromagnetic or electro-optical devices and possesses superconducting properties.

  10. Sintering of powder mixtures and the growth of ferrous powder metallurgy

    Microsoft Academic Search

    K. S Narasimhan

    2001-01-01

    Advances in the understanding of sintering of powder mixtures contributed significantly to the growth of ferrous powder metallurgy industry. Solid-state sintering and liquid-phase activated sintering play an important role in the sintering of powder mixtures. In this paper, sintering of iron powder with graphite; iron powder with copper and graphite; iron powder with nickel and graphite; iron powder with phosphorus;

  11. Superplastic deformation mechanism in powder metallurgy magnesium alloys and composites

    Microsoft Academic Search

    H. Watanabe; T. Mukai; M. Mabuchi; K. Higashi

    2001-01-01

    The parametric dependencies for superplastic flow in powder metallurgy (PM) magnesium alloys and composites were characterized so as to elucidate the deformation mechanism. The mechanism was proposed to be slip accommodated grain boundary sliding. However, the PM alloys and composites were strengthened at low temperatures below ?550K. This was different from the case in ingot metallurgy (IM) magnesium alloys, that

  12. Metallurgical examination of powder metallurgy uranium alloy welds

    Microsoft Academic Search

    G. M. Alexander-Morrison; A. G. Dobbins; R. K. Holbert; M. W. Doughty

    1986-01-01

    Inertia welding provided a successful technique for joining full density, powder metallurgy uranium-6 wt pct niobium alloy.\\u000a Initial joining attempts concentrated on the electron beam method, but this method failed to produce a sound weld. The electron\\u000a beam welds and the inertia welds were evaluated by radiography and metallography. Electron beam welds were attempted on powder\\u000a metallurgy plates which contained

  13. CHARACTERIZATION AND PROPERTIES OF ALUMINUM COMPOSITE MATERIALS PREPARED BY POWDER METALLURGY TECHNIQUES USING CERAMIC SOLID WASTES

    Microsoft Academic Search

    L. Ma. Flores-Vélez; J. Chávez; L. Hernández; O. Domínguez

    2001-01-01

    This work provides preliminary results of aluminum metal matrix composites (MMCs) reinforced with granulated slag (GS) and electric arc furnace dust (EAFD). The present work concerns the synthesis and properties of Al\\/GS and Al\\/EAFD composites based on powder metallurgy techniques. The hardness and compressive strength of the sintering compacts were determined to compare the mechanical properties of the composite material

  14. Powder metallurgy process for manufacturing core projectile

    NASA Astrophysics Data System (ADS)

    Akbar, Taufik; Setyowati, Vuri Ayu; Widyastuti

    2013-09-01

    Bullets are part of the defense equipment which the development is very rapid. There are a variety of forms but the bullet Lead is a metal that has always been used for applications projectiles. Lead core constituent materials are combined with antimony. In this research will be conducted by making the material for the core projectile with Tin Lead. The addition of Tin will increase the stiffness of Lead which is soft in nature. The Lead Tin composition variation was given in 10% weight of Sn. The manufacturing process using powder metallurgy using temperature and holding time variations of sintering at 100, 150, and 200°C for 1,2, and 3 hours. XRD samples will be tested to determine the form and phase morphology was observed using SEM-EDX. These results revealed that Pb-10%wtSn Composite which is sintered in temperature 200°C for 3 hours has the greatest density, 10.695 g/cm3 as well as the smallest porosity, 2.2%. In agreement with theoretical analysis that increasing higher temperature and longer holding time give decrease in porosity level due to activation energy which further promotes grain growth. Moreover, there is no intermetallic phase formation as well as no oxide found on composites.

  15. Compaction of Titanium Powders

    SciTech Connect

    Stephen J. Gerdemann; Paul D. Jablonski

    2010-11-01

    Accurate modeling of powder densification has been an area of active research for more than 60 years. The earliest efforts were focused on linearization of the data because computers were not readily available to assist with curve-fitting methods. In this work, eight different titanium powders (three different sizes of sponge fines <150 ?m, <75 ?m, and < 45 ?m; two different sizes of a hydride-dehydride [HDH] <75 ?m and < 45 ?m; an atomized powder; a commercially pure [CP] Ti powder from International Titanium Powder [ITP]; and a Ti 6 4 alloy powder) were cold pressed in a single-acting die instrumented to collect stress and deformation data during compaction. From these data, the density of each compact was calculated and then plotted as a function of pressure. The results show that densification of all the powders, regardless of particle size, shape, or chemistry, can be modeled accurately as the sum of an initial density plus the sum of a rearrangement term and a work-hardening term. These last two terms are found to be a function of applied pressure and take the form of an exponential rise.

  16. Compaction of Titanium Powders

    SciTech Connect

    Gerdemann, Stephen,J; Jablonski, Paul, J

    2011-05-01

    Accurate modeling of powder densification has been an area of active research for more than 60 years. The earliest efforts were focused on linearization of the data because computers were not readily available to assist with curve-fitting methods. In this work, eight different titanium powders (three different sizes of sponge fines<150 {micro}m,<75 {micro}m, and<45 {micro}m; two different sizes of a hydride-dehydride [HDH]<75 {micro}m and<45 {micro}m; an atomized powder; a commercially pure [CP] Ti powder from International Titanium Powder [ITP]; and a Ti 6 4 alloy powder) were cold pressed in a single-acting die instrumented to collect stress and deformation data during compaction. From these data, the density of each compact was calculated and then plotted as a function of pressure. The results show that densification of all the powders, regardless of particle size, shape, or chemistry, can be modeled accurately as the sum of an initial density plus the sum of a rearrangement term and a work-hardening term. These last two terms are found to be a function of applied pressure and take the form of an exponential rise.

  17. Aluminium powder metallurgy technology for high-strength applications

    Microsoft Academic Search

    J. R. Pickens

    1981-01-01

    A literature survey of aluminium powder metallurgy (PM) for high-strength applications was undertaken. Improvements in aluminium—base alloys made via ingot metallurgy (IM) are reaching the point of diminishing returns. PM offers an alternative technology, capable of producing alloys having improved fatigue, corrosion, and stress-corrosion resistance, as well as improved strength and toughness at room or elevated temperatures. The steps involved

  18. Generalised yield criteria of porous sintered powder metallurgy metals

    Microsoft Academic Search

    R. Narayanasamy; R. Ponalagusamy; K. R. Subramanian

    2001-01-01

    A new form of yield criterion considering an anisotropic parameter for porous sintered powder metallurgy metals has been proposed in this technical paper. In addition to the above, the flow rule with anisotropic parameter for porous metal is introduced. The mathematical expression for the calculation of flow stress in the case of simple compression or tension test is deduced from

  19. One step HIP canning of powder metallurgy composites

    NASA Technical Reports Server (NTRS)

    Juhas, John J. (inventor)

    1990-01-01

    A single step is relied on in the canning process for hot isostatic pressing (HIP) powder metallurgy composites. The binders are totally removed while the HIP can of compatible refractory metal is sealed at high vacuum and temperature. This eliminates outgassing during hot isostatic pressing.

  20. Powder-metallurgy superalloy strengthened by a secondary gamma phase.

    NASA Technical Reports Server (NTRS)

    Kotval, P. S.

    1971-01-01

    Description of experiments in which prealloyed powders of superalloy compositions were consolidated by extrusion after the strengthening by precipitation of a body-centered tetragonal gamma secondary Ni3 Ta phase. Thin foil electron microscopy showed that the mechanical properties of the resultant powder-metallurgy product were correlated with its microstructure. The product exhibited high strength at 1200 F without loss of ductility, after thermomechanical treatment and aging.

  1. Near-Net Shape Powder Metallurgy Rhenium Thruster

    NASA Technical Reports Server (NTRS)

    Leonhardt, Todd; Hamister, Mark; Carlen, Jan C.; Biaglow, James; Reed, Brian

    2001-01-01

    This paper describes the development of a method to produce a near-net shape (NNS) powder metallurgy (PM) rhenium combustion chamber of the size 445 N (100 lbf) used in a high performance liquid apogee engine. These engines are used in low earth Orbit and geostationary orbit for satellite positioning systems. The developments in near-net shape powder metallurgy rhenium combustion chambers reported in this paper will reduce manufacturing cost of the rhenium chambers by 25 percent, and reduce the manufacturing time by 30 to 40 percent. The quantity of rhenium metal powder used to produce a rhenium chamber is reduced by approximately 70 percent and the subsequent reduction in machining schedule and costs is nearly 50 percent.

  2. A powder metallurgy approach for production of innovative radioactive waste forms

    SciTech Connect

    Keiser, D.D. Jr.; Crawford, D.C. [Argonne National Lab., Idaho Falls, ID (United States); Bhaduri, S. [Univ. of Idaho, Moscow, ID (United States)] [and others

    1997-07-01

    The feasibility of producing a single metal-matrix composite form rather than two separate forms consisting of a cast metal alloy ingot (such as Type 316SS + Zr) and a ceramic glass-bonded zeolite Na{sub 12}(AlO{sub 2}){sub 12}(SiO{sub 2}){sub 12} has been demonstrated. This powder metallurgy approach consists of mixing the powder of the two separate waste forms together followed by compaction by hot isostatic pressing. Such a radioactive waste form would have the potential advantages of reducing the total waste volume, good thermal conductivity, stability, and surfaces with limited oxide layer formation. 5 refs., 8 figs., 2 tabs.

  3. Laboratory Powder Metallurgy Makes Tough Aluminum Sheet

    NASA Technical Reports Server (NTRS)

    Royster, D. M.; Thomas, J. R.; Singleton, O. R.

    1993-01-01

    Aluminum alloy sheet exhibits high tensile and Kahn tear strengths. Rapid solidification of aluminum alloys in powder form and subsequent consolidation and fabrication processes used to tailor parts made of these alloys to satisfy such specific aerospace design requirements as high strength and toughness.

  4. Generalized mathematical model of thermal diffusion in powder metallurgy

    NASA Astrophysics Data System (ADS)

    Lyashenko, V.; Hryhorova, Ð.¢.

    2014-11-01

    Mathematical models of thermal processes that occur in the powder metallurgy during sintering, hot pressing, wire and rods annealing are examined from a unified physical point of view. Nonlinear initial-boundary value problems for linear equations of heat conduction and diffusion in fixed and moving axially symmetric environment with constant and variable thermal characteristics and coefficients, which are permanent or piecewise monotonic functions, are considered in mathematical models. Problems are solved by numerically-analytical methods involving Crank-Nicolson and Douglas-Han implicit difference schemes. In describing the process of high thermal diffusion, the boundary condition that relates to the change in the concentration of impurities in the heated region, depending on the temperature, is formulated. A block diagram of the control process of thermal diffusion in powder metallurgy is proposed.

  5. Milling and Drilling Evaluation of Stainless Steel Powder Metallurgy Alloys

    SciTech Connect

    Lazarus, L.J.

    2001-12-10

    Near-net-shape components can be made with powder metallurgy (PM) processes. Only secondary operations such as milling and drilling are required to complete these components. In the past and currently production components are made from powder metallurgy (PM) stainless steel alloys. process engineers are unfamiliar with the difference in machining properties of wrought versus PM alloys and have had to make parts to develop the machining parameters. Design engineers are not generally aware that some PM alloy variations can be furnished with machining additives that greatly increase tool life. Specimens from a MANTEC PM alloy property study were made available. This study was undertaken to determine the machining properties of a number of stainless steel wrought and PM alloys under the same conditions so that comparisons of their machining properties could be made and relative tool life determined.

  6. Modulus Dependence on Large Scale Porosity of Powder Metallurgy Steel

    NASA Astrophysics Data System (ADS)

    Allison, P. G.; Horstemeyer, M. F.; Brown, H. R.

    2012-07-01

    This article compares the existing theoretical expressions for the porosity dependence on elastic constants to experimental data for a commercially available material, FC-0205 powder metallurgy (PM) steel. The modulus of compression, tension, effective torsion, and ultrasound-based data at varying porosity levels are plotted graphically against the theoretical expressions. An equation by McAdam ( J. Iron Steel Inst. Lond., 1950, 168, p 346) was able to most accurately predict the experimental data with the adjustment of only one material constant.

  7. [Use of powder metallurgy for development of implants of Co-Cr-Mo alloy powder].

    PubMed

    Dabrowski, J R

    2001-04-01

    This paper discusses the application of powder metallurgy for the development of porous implantation materials. Powders obtained from Co-Cr-Mo alloy with different carbon content by water spraying and grinding, have been investigated. Cold pressing and rotary re-pressing methods were used for compressing the powder. It was found that the sintered materials obtained from water spraying have the most advantageous properties. PMID:11388037

  8. Prediction of Elastic Behavior of Sintered Metal Powder from the Ultrasonic Velocities of Green Compacts

    NASA Astrophysics Data System (ADS)

    Phani, K. K.; Sanyal, Dipayan

    2008-04-01

    A novel procedure for the estimation of the elastic properties of the sintered and compacted metal powders from the ultrasonic velocities of the green compact alone has been proposed in this article. The methodology has been validated for sintered iron powder and copper powder compacts as well as for consolidated silver powder compacts of various processing histories, powder sizes, and pore morphology. The predicted elastic moduli, including the derived modulus (Poisson’s ratio), are found to be in reasonably good agreement with the measured data reported in the literature. The proposed method can be developed as a potent tool for the quantitative nondestructive evaluation (QNDE) of powder metallurgy products.

  9. Application of superalloy powder metallurgy for aircraft engines

    NASA Technical Reports Server (NTRS)

    Dreshfield, R. L.; Miner, R. V., Jr.

    1980-01-01

    In the last decade, Government/Industry programs have advanced powder metallurgy-near-net-shape technology to permit the use of hot isostatic pressed (HIP) turbine disks in the commercial aircraft fleet. These disks offer a 30% savings of input weight and an 8% savings in cost compared in cast-and-wrought disks. Similar savings were demonstrated for other rotating engine components. A compressor rotor fabricated from hot-die-forged-HIP superalloy billets revealed input weight savings of 54% and cost savings of 35% compared to cast-and-wrought parts. Engine components can be produced from compositions such as Rene 95 and Astroloy by conventional casting and forging, by forging of HIP powder billets, or by direct consolidation of powder by HIP. However, each process produces differences in microstructure or introduces different defects in the parts. As a result, their mechanical properties are not necessarily identical. Acceptance methods should be developed which recognize and account for the differences.

  10. NOVEL METHODOLOGY TO QUANTIFY TOOL WEAR IN POWDER METALLURGY

    Microsoft Academic Search

    James K. Thompson; Seong Jin Park; Randall M. German; Fehim Findik; Arockiasamy Antonyraj

    A new methodology was developed to quantify tool wear during the die compaction process. The newly developed method is a non-destructive test using silicon rubber to transcript die surface profiles. Tool wear was measured by recording surface roughness of the cylindrical die molds on a surface profiler. To validate this procedure, an aluminum alloy powder was compacted to examine the

  11. Properties of porous magnesium prepared by powder metallurgy.

    PubMed

    ?apek, Jaroslav; Vojt?ch, Dalibor

    2013-01-01

    Porous magnesium-based materials are biodegradable and promising for use in orthopaedic applications, but their applications are hampered by their difficult fabrication. This work reports the preparation of porous magnesium materials by a powder metallurgy technique using ammonium bicarbonate as spacer particles. The porosity of the materials depended on the amount of ammonium bicarbonate and was found to have strong negative effects on flexural strength and corrosion behaviour. However, the flexural strength of materials with porosities of up to 28 vol.% was higher than the flexural strength of non-metallic biomaterials and comparable with that of natural bone. PMID:25428111

  12. In vitro bioactivity of a biocomposite fabricated from HA and Ti powders by powder metallurgy method

    Microsoft Academic Search

    C. Q. Ning; Y. Zhou

    2002-01-01

    Traditionally, hydroxyapatite was used as a coating material on titanium substrate by various techniques. In the present work, a biocomposite was successfully fabricated from hydroxyapatite and titanium powders by powder metallurgy method. Bioactivity of the composite in a simulated body fluid (SBF) was investigated. Main crystal phases of the as-fabricated composite are found to be Ti2O, CaTiO3, CaO, ?-Ti and

  13. Ceramic Inclusions in Powder Metallurgy Disk Alloys: Characterization and Modeling

    NASA Technical Reports Server (NTRS)

    Bonacuse, Peter J.

    2001-01-01

    Powder metallurgy alloys are increasingly used in gas turbine engines, especially in turbine disk applications. Although powder metallurgy materials have many advantages over conventionally cast and wrought alloys (higher strength, higher temperature capability, etc.), they suffer from the rare occurrence of ceramic defects (inclusions) that are inherent to the powder atomization process. These inclusions can have a potentially large detrimental effect on the durability of individual components. An inclusion in a high stress location can act as a site for premature crack initiation and thereby considerably reduce the fatigue life. Because these inclusions are exceedingly rare, they typically do not reveal themselves in the process of characterizing the material for a particular application (the cumulative volume of the test bars in a fatigue life characterization is typically on the order of a single actual component). Ceramic inclusions have, however, been found to be the root cause of a number of catastrophic engine failures. To investigate the effect of these inclusions in detail, we have undertaken a study where known populations of ceramic particles, whose composition and morphology are designed to mimic the "natural" inclusions, are added to the precursor powder. Surface-connected inclusions have been found to have a particularly large detrimental effect on fatigue life; therefore, the quantity of ceramic "seeds" added is calculated to ensure that a minimum number will intersect the surface of the fatigue test bars. Because the ceramic inclusions are irregularly shaped and have a tendency to break up in the process of extrusion and forging, a method of calculating the probability of occurrence and expected intercepted surface area was needed. We have developed a Monte Carlo simulation to determine the distributions of these parameters and have verified the simulated results with observations of ceramic inclusions found in macroscopic slices from extrusions and forgings. Fatigue specimens have been machined from Udimet 720 (a powder metallurgy superalloy) forgings, to determine the effects of the inclusions on fatigue life. The ultimate goal of this study will be to use probabilistic methods to determine the reliability detriment that can be attributed to these ceramic inclusions. This work has been supported by the Ultra Safe and Ultra- Efficient Engine Technologies programs.

  14. DC Plasma Technology Applied to Powder Metallurgy: an Overview

    NASA Astrophysics Data System (ADS)

    N. Klein, A.; P. Cardoso, R.; C. Pavanati, H.; Binder, C.; M. Maliska, A.; Hammes, G.; Fusao, D.; Seeber, A.; F. Brunatto, S.; L. R. Muzart, J.

    2013-01-01

    DC plasma is a very promising technology for processing different materials, and is becoming especially interesting when low environmental impact and high-performance treatments are needed. Some of the intrinsic characteristics of DC plasma technology, which make it suitable for powder metallurgy (PM) and powder injection molding (PIM) parts production, are low-pressure processing and plasma environment high reactivity. Moreover it can be considered as a highly competitive green technology. In this work, an overview of some of the important DC plasma techniques applied to PM and PIM parts processing is presented. Emphasis is given to the descriptions of the main characteristics and the technique potentials of plasma-assisted nitriding, plasma-assisted thermal debinding, plasma-assisted sintering, and simultaneously plasma-assisted sintering and surface alloying. The aspects presented and discussed in this paper indicate that DC plasma processes are promising and competitive techniques for PM and PIM parts processing.

  15. MESOSCALE SIMULATIONS OF POWDER COMPACTION

    SciTech Connect

    Lomov, Ilya; Fujino, Don; Antoun, Tarabay; Liu, Benjamin [Lawrence Livermore National Laboratory, P. O. Box 808, Livermore CA 94551 (United States)

    2009-12-28

    Mesoscale 3D simulations of shock compaction of metal and ceramic powders have been performed with an Eulerian hydrocode GEODYN. The approach was validated by simulating a well-characterized shock compaction experiment of a porous ductile metal. Simulation results using the Steinberg material model and handbook values for solid 2024 aluminum showed good agreement with experimental compaction curves and wave profiles. Brittle ceramic materials are not as well studied as metals, so a simple material model for solid ceramic (tungsten carbide) has been calibrated to match experimental compaction curves. Direct simulations of gas gun experiments with ceramic powders have been performed and showed good agreement with experimental data. The numerical shock wave profile has same character and thickness as that measured experimentally using VISAR. The numerical results show reshock states above the single-shock Hugoniot line as observed in experiments. We found that for good quantitative agreement with experiments 3D simulations are essential.

  16. Phase Stability of a Powder Metallurgy Disk Superalloy

    NASA Technical Reports Server (NTRS)

    Gabb, Timothy P.; Gayda, John; Kantzos, P.; Telesman, Jack; Gang, Anita

    2006-01-01

    Advanced powder metallurgy superalloy disks in aerospace turbine engines now entering service can be exposed to temperatures approaching 700 C, higher than those previously encountered. They also have higher levels of refractory elements, which can increase mechanical properties at these temperatures but can also encourage phase instabilities during service. Microstructural changes including precipitation of topological close pack phase precipitation and coarsening of existing gamma' precipitates can be slow at these temperatures, yet potentially significant for anticipated disk service times exceeding 1,000 h. The ability to quantify and predict such potential phase instabilities and degradation of capabilities is needed to insure structural integrity and air worthiness of propulsion systems over the full life cycle. A prototypical advanced disk superalloy was subjected to high temperature exposures, and then evaluated. Microstructural changes and corresponding changes in mechanical properties were quantified. The results will be compared to predictions of microstructure modeling software.

  17. Method for forming biaxially textured articles by powder metallurgy

    DOEpatents

    Goyal, Amit (Knoxville, TN); Williams, Robert K. (Knoxville, TN); Kroeger, Donald M. (Knoxville, TN)

    2002-01-01

    A method of preparing a biaxially textured alloy article comprises the steps of preparing a mixture comprising Ni powder and at least one powder selected from the group consisting of Cr, W, V, Mo, Cu, Al, Ce, YSZ, Y, Rare Earths, (RE), MgO, CeO.sub.2, and Y.sub.2 O.sub.3 ; compacting the mixture, followed by heat treating and rapidly recrystallizing to produce a biaxial texture on the article. In some embodiments the alloy article further comprises electromagnetic or electro-optical devices and possesses superconducting properties.

  18. Advances in powder metallurgy - 1991. Vol. 5 - P\\/M materials; Proceedings of the Powder Metallurgy Conference and Exhibition, Chicago, IL, June 9-12, 1991

    Microsoft Academic Search

    L. F. Pease; R. J. Sansoucy

    1991-01-01

    The present volume powder metallurgy materials discusses the state of the PM industry, a metallurgical evaluation of new steel powders, design criteria for the manufacturing of low-alloy steel powders, and homogenization processing of a PM maraging steel. Attention is given to the corrosion resistance of full density sintered 316 SS, the performance characteristics of a new sinter-hardening low-alloy steel, wear

  19. Effects of carbon and hafnium concentrations in wrought powder-metallurgy superalloys based on NASA 2B-11 alloy

    NASA Technical Reports Server (NTRS)

    Miner, R. V., Jr.

    1976-01-01

    A candidate alloy for advanced-temperature turbine engine disks, and four modifications of that alloy with various C and Hf concentrations were produced as cross-rolled disks from prealloyed powder that was hot isostatically compacted. The mechanical properties, microstructures, and phase relations of the alloys are discussed in terms of their C and Hf concentrations. A low-C and high-Hf modification of IIB-11 had the best balance of mechanical properties for service below about 750 C. Because of their finer grain sizes, none of the powder-metallurgy alloys produced had the high-temperature rupture strength of conventionally cast and wrought IIB-11.

  20. Thixoforming of Stellite Powder Compacts

    NASA Astrophysics Data System (ADS)

    Hogg, S. C.; Atkinson, H. V.; Kapranos, P.

    2007-04-01

    Thixoforming involves processing metallic alloys in the semi-solid state. The process requires the microstructure to be spheroidal when part-solid and part-liquid i.e. to consist of solid spheroids surrounded by liquid. The aim of this work was to investigate whether powder compacts can be used as feedstock for thixoforming and whether the consolidating pressure in the thixoformer can be used to remove porosity from the compact. The powder compacts were made from stellite 6 and stellite 21 alloys, cobalt-based alloys widely used for e.g. manufacturing prostheses. Isothermal heat treatments of small samples in the consolidated state showed the optimum thixoforming temperature to be in the range 1340°C-1350°C for both materials. The alloys were thixoformed into graphite dies and flowed easily to fill the die. Porosity in the thixoformed components was lower than in the starting material. Hardness values at various positions along the radius of the thixoformed demonstrator component were above the specification for both alloys.

  1. A neural network approach for selection of powder metallurgy materials and process parameters

    Microsoft Academic Search

    R. P. Cherian; L. N. Smith; P. S. Midha

    2000-01-01

    The artificial neural network (NN) methodology presented in this paper has been developed for selection of powder and process parameters for Powder Metallurgy (PM) part manufacture. This methodology differs from the statistical modelling of mechanical properties in that it is not necessary to make assumptions regarding the form of the functions relating input and output variables. Employment of a NN

  2. Investigation of the Environmental Durability of a Powder Metallurgy Material

    NASA Technical Reports Server (NTRS)

    Ward, LaNita D.

    2004-01-01

    PM304 is a NASA-developed composite powder metallurgy material that is being developed for high temperature applications such as bushings in high temperature industrial furnace conveyor systems. My goal this summer was to analyze and evaluate the effects that heat exposure had on the PM304 material at 500 C and 650 C. The material is composed of Ni-Cr, Ag, Cr2O3, and eutectic BaF2-CaF2. PM304 is designed to eliminate the need for oil based lubricants in high temperature applications, while reducing friction and wear. However, further investigation was needed to thoroughly examine the properties of PM304. The effects of heat exposure on PM304 bushings were investigated. This investigation was necessary due to the high temperatures that the material would be exposed to in a typical application. Each bushing was cut into eight sections. The specimens were heated to 500 C or 650 C for time intervals from 1 hr to 5,000 hrs. Control specimens were kept at room temperature. Weight and thickness measurements were taken before and after the bushing sections were exposed to heat. Then the heat treated specimens were mounted and polished side by side with the control specimens. This enabled optical examination of the material's microstructure using a metallograph. The specimens were also examined with a scanning electron microscope (SEM). The microstructures were compared to observe the effects of the heat exposure. Chemical analysis was done to investigate the interactions between Ni-Cr and BaF2-CaF2 and between Cr2O3 and BaF2-CaF2 at high temperature. To observe this, the two compounds that were being analyzed were mixed in a crucible in varied weight percentages and heated to 1100 C in a furnace for approximately two hours. Then the product was allowed to cool and was then analyzed by X-ray diffraction. Interpretation of the results is in progress.

  3. Elevated temperature crack growth in advanced powder metallurgy aluminum alloys

    NASA Technical Reports Server (NTRS)

    Porr, William C., Jr.; Gangloff, Richard P.

    1990-01-01

    Rapidly solidified Al-Fe-V-Si powder metallurgy alloy FVS0812 is among the most promising of the elevated temperature aluminum alloys developed in recent years. The ultra fine grain size and high volume fraction of thermally stable dispersoids enable the alloy to maintain tensile properties at elevated temperatures. In contrast, this alloy displays complex and potentially deleterious damage tolerant and time dependent fracture behavior that varies with temperature. J-Integral fracture mechanics were used to determine fracture toughness (K sub IC) and crack growth resistance (tearing modulus, T) of extruded FVS0812 as a function of temperature. The alloy exhibits high fracture properties at room temperature when tested in the LT orientation, due to extensive delamination of prior ribbon particle boundaries perpendicular to the crack front. Delamination results in a loss of through thickness constraint along the crack front, raising the critical stress intensity necessary for precrack initiation. The fracture toughness and tensile ductility of this alloy decrease with increasing temperature, with minima observed at 200 C. This behavior results from minima in the intrinsic toughness of the material, due to dynamic strain aging, and in the extent of prior particle boundary delaminations. At 200 C FVS0812 fails at K levels that are insufficient to cause through thickness delamination. As temperature increases beyond the minimum, strain aging is reduced and delamination returns. For the TL orientation, K (sub IC) decreased and T increased slightly with increasing temperature from 25 to 316 C. Fracture in the TL orientation is governed by prior particle boundary toughness; increased strain localization at these boundaries may result in lower toughness with increasing temperature. Preliminary results demonstrate a complex effect of loading rate on K (sub IC) and T at 175 C, and indicate that the combined effects of time dependent deformation, environment, and strain aging may play a role. Fractography showed that microvoid coalescence was the microscopic mode of fracture in FVS0812 under all testing conditions. However, the nature of the microvoids varied with test temperature and loading rate, and is complex for the fine grain and dipersoid sizes of FVS0812.

  4. Testing of electroformed deposited iridium/powder metallurgy rhenium rockets

    NASA Technical Reports Server (NTRS)

    Reed, Brian D.; Dickerson, Robert

    1996-01-01

    High-temperature, oxidation-resistant chamber materials offer the thermal margin for high performance and extended lifetimes for radiation-cooled rockets. Rhenium (Re) coated with iridium (Ir) allow hours of operation at 2200 C on Earth-storable propellants. One process for manufacturing Ir/Re rocket chambers is the fabrication of Re substrates by powder metallurgy (PM) and the application of Ir coatings by using electroformed deposition (ED). ED Ir coatings, however, have been found to be porous and poorly adherent. The integrity of ED Ir coatings could be improved by densification after the electroforming process. This report summarizes the testing of two 22-N, ED Ir/PM Re rocket chambers that were subjected to post-deposition treatments in an effort to densify the Ir coating. One chamber was vacuum annealed, while the other chamber was subjected to hot isostatic pressure (HIP). The chambers were tested on gaseous oxygen/gaseous hydrogen propellants, at mixture ratios that simulated the oxidizing environments of Earth-storable propellants. ne annealed ED Ir/PM Re chamber was tested for a total of 24 firings and 4.58 hr at a mixture ratio of 4.2. After only 9 firings, the annealed ED Ir coating began to blister and spall upstream of the throat. The blistering and spalling were similar to what had been experienced with unannealed, as-deposited ED Ir coatings. The HIP ED Ir/PM Re chamber was tested for a total of 91 firings and 11.45 hr at mixture ratios of 3.2 and 4.2. The HIP ED Ir coating remained adherent to the Re substrate throughout testing; there were no visible signs of coating degradation. Metallography revealed, however, thinning of the HIP Ir coating and occasional pores in the Re layer upstream of the throat. Pinholes in the Ir coating may have provided a path for oxidation of the Re substrate at these locations. The HIP ED Ir coating proved to be more effective than vacuum annealed and as-deposited ED Ir. Further densification is still required to match the integrity of chemically vapor deposited Ir coatings. Despite this, the successful long duration testing of the HIP ED Ir chamber, in an oxidizing environment comparable to Earth-storable propellants, demonstrated the viability of this Ir/Re rocket fabrication process.

  5. In vitro bioactivity of a biocomposite fabricated from HA and Ti powders by powder metallurgy method.

    PubMed

    Ning, C Q; Zhou, Y

    2002-07-01

    Traditionally, hydroxyapatite was used as a coating material on titanium substrate by various techniques. In the present work, a biocomposite was successfully fabricated from hydroxyapatite and titanium powders by powder metallurgy method. Bioactivity of the composite in a simulated body fluid (SBF) was investigated. Main crystal phases of the as-fabricated composite are found to be Ti2O, CaTiO3, CaO, alpha-Ti and a TiP-like phase. When the composite is immersed in the simulated body fluid for a certain time, a poor-crystallized, calcium-deficient, carbonate-containing apatite film will form on the surface of the composite. The time required to induce apatite nucleation is within 2 h. In addition, the apatite is also incorporated with a little magnesium and chlorine element. It is found that Ti2O has the ability to induce the formation of bone-like apatite in the SBF. And a dissolve of the CaO phase could also provide favorable conditions for the apatite formation, by forming open pores on the surface of the composite and increasing the degree of supersaturation of the SBF with respect to the apatite. PMID:12069332

  6. A novel powder metallurgy-based method for the recycling of aluminum adapted to a small island developing state in the

    E-print Network

    Boyer, Edmond

    1 A novel powder metallurgy-based method for the recycling of aluminum adapted to a small island of the advantages of the powder metallurgy process. The properties of the recycled parts make them competitive,4 (2007) 1-22" #12;2 Keywords: End-of-life products management, Aluminum, powder metallurgy, recycling

  7. Some aspects on workability of aluminium–iron powder metallurgy composite during cold upsetting

    Microsoft Academic Search

    R. Narayanasamy; T. Ramesh; K. S. Pandey

    2005-01-01

    Workability is a measure of the extent of deformation that a powder metallurgy materials can withstand prior to fracture occurred in the forming or upsetting processes. Ductile fracture is the most common mode of failure in bulk forming process. The formability is a complicated phenomenon, dependent upon the process as well as the material parameters. A complete experimental investigation on

  8. Creep behavior of an aluminum 2024 alloy produced by powder metallurgy

    Microsoft Academic Search

    L. Kloc; S. Spigarelli; E. Cerri; E. Evangelista; T. G. Langdon

    1997-01-01

    Creep tests were conducted over a range of temperatures from 523 to 603 K on an unreinforced 2024 Al alloy fabricated by powder metallurgy processing. The creep curves under all testing conditions exhibit a brief quasi-steady-state condition and then a very extended tertiary stage leading to failure. A logarithmic plot of the minimum creep rate against the applied stress leads

  9. Mechanical properties of modified low cobalt powder metallurgy Udimet 700 type alloys

    NASA Technical Reports Server (NTRS)

    Harf, Fredric H.

    1989-01-01

    Eight superalloys derived from Udimet 700 were prepared by powder metallurgy, hot isostatically pressed, heat treated and their tensile and creep rupture properties determined. Several of these alloys displayed properties superior to those of Udimet 700 similarly prepared, in one case exceeding the creep rupture life tenfold. Filter clogging by extracted gamma prime, its measurement and significance are discussed in an appendix.

  10. Powder metallurgy approaches to high temperature components for gas turbine engines

    NASA Technical Reports Server (NTRS)

    Probst, H. B.

    1974-01-01

    Research is reported for the tensile strength, ductility, and heat performance characterisitics of powder metallurgy (p/m) superalloys. Oxide dispersion strengthened alloys were also evaluated for their strength during thermal processing. The mechanical attributes evident in both p/m supperalloys and dispersion strengthened alloys are discussed in terms of research into their possible combination.

  11. Corrosion protection of different environmentally friendly coatings on powder metallurgy magnesium

    Microsoft Academic Search

    M. Carboneras; L. S. Hernández; J. A. del Valle; M. C. García-Alonso; M. L. Escudero

    2010-01-01

    Pure magnesium was processed by a powder metallurgy (PM) route to generate microstructural features that provide higher mechanical properties than those of cast pure magnesium and commercial AZ31 alloy. Nevertheless, corrosion resistance of PM Mg needs to be improved if this material is to be used for structural applications in a corrosive medium. In the present work, the corrosion protection

  12. Sintering of copper-alumina composites through blending and mechanical alloying powder metallurgy routes

    Microsoft Academic Search

    G. S. Upadhyaya

    1995-01-01

    Dispersion-strengthened copper has the ability to retain most of its properties at elevated temperatures. Among various processes, the powder metallurgy preparation route is ideal because of its efficient dispersion of fine particles. In the present investigation copper composites containing 0–3 wt%. Al2O3 were sintered in hydrogen at temperatures of 800°C and 900°C. The powders were prepared through the blending and

  13. Copper matrix SiC and Al 2O 3 particulate composites by powder metallurgy technique

    Microsoft Academic Search

    S. F Moustafa; Z Abdel-Hamid; A. M Abd-Elhay

    2002-01-01

    Copper matrix reinforced with either Ni-coated or uncoated SiC and Al2O3 particulate composites were made by means of the powder metallurgy route. The reinforcement particles of SiC and Al2O3 were coated with a thin layer of nickel by electroless method. The coated or uncoated reinforcement particles of either SiC or Al2O3 were added to copper metal powders with nominal loading

  14. Novel powder metallurgy technique for development of Fe–P-based soft magnetic materials

    Microsoft Academic Search

    Jiten Das; K. Chandra; P. S. Misra; B. Sarma

    2008-01-01

    Novel powder metallurgy technique (hot forging technique) is used for the development of high-density Fe–P-based soft magnetic alloys such as Fe–P binary, Fe–P–Cr ternary and Fe–P–Cr–Si quaternary alloys. In this process, mild steel encapsulated powders were hot forged into slabs, hot rolled and annealed to relieve the residual stresses. These alloys were subjected to in-house characterization, e.g. density and theoretically

  15. Biaxially textured articles formed by power metallurgy

    DOEpatents

    Goyal, Amit; Williams, Robert K.; Kroeger, Donald M.

    2003-08-26

    A biaxially textured alloy article having a magnetism less than pure Ni includes a rolled and annealed compacted and sintered powder-metallurgy preform article, the preform article having been formed from a powder mixture selected from the group of mixtures consisting of: at least 60 at % Ni powder and at least one of Cr powder, W powder, V powder, Mo powder, Cu powder, Al powder, Ce powder, YSZ powder, Y powder, Mg powder, and RE powder; the article having a fine and homogeneous grain structure; and having a dominant cube oriented {100}<100> orientation texture; and further having a Curie temperature less than that of pure Ni.

  16. Application of superalloy powder metallurgy for aircraft engines

    NASA Technical Reports Server (NTRS)

    Dreshfield, R. L.; Miner, R. V., Jr.

    1980-01-01

    The results of the Materials for Advanced Turbine Engines (MATE) program initiated by NASA are presented. Mechanical properties comparisons are made for superalloy parts produced by as-HIP powder consolidation and by forging of HIP consolidated billets. The effect of various defects on the mechanical properties of powder parts are shown.

  17. Investigation of machinability of iron based metal matrix composite (MMC) powder metallurgy parts

    NASA Astrophysics Data System (ADS)

    Szalay, Tibor; Czampa, Miklós; Markos, Sándor; Farkas, Balázs

    2012-09-01

    One of the advantages of powder metallurgy technology is that we may produce the final geometry of the required part saving considerable time and cost. However there are several applications that require parts need additional machining for example when the product contains threads, cross bore or slots. In these cases cutting of the hard and porous material may causes difficulties in manufacturing. The aim of the introduced research is the experimental investigation of the machinability of the iron based MMC powder metallurgy parts, determining the favourable composition of the powder and advantageous process parameters regarding the properties of the machinability. The research try to answer to the challenge of the poorly defined expression: machinability, and after defining the features and methods of the evaluation we develop advises for the proper technology parameters.

  18. In vitro degradation and cytotoxicity of Mg/Ca composites produced by powder metallurgy.

    PubMed

    Zheng, Y F; Gu, X N; Xi, Y L; Chai, D L

    2010-05-01

    Mg/Ca (1 wt.%, 5 wt.%, 10 wt.% Ca) composites were prepared from pure magnesium and calcium powders using the powder metallurgy method, aiming to enlarge the addition of Ca content without the formation of Mg(2)Ca. The microstructures, mechanical properties and cytotoxicities of Mg/Ca composite samples were investigated. The corrosion of Mg/Ca composites in Dulbecco's modified Eagle's medium (DMEM) for various immersion intervals was studied by electrochemical impedance spectroscopy measurements and environmental scanning electron microscope, with the concentrations of released Mg and Ca ions in DMEM for various immersion time intervals being measured. It was shown that the main constitutional phases were Mg and Ca, which were uniformly distributed in the Mg matrix. The ultimate tensile strength (UTS) and elongation of experimental composites decreased with increasing Ca content, and the UTS of Mg/1Ca composite was comparable with that of as-extruded Mg-1Ca alloy. The corrosion potential increased with increasing Ca content, whereas the current density and the impedance decreased. It was found that the protective surface film formed quickly at the initial immersion stage. With increasing immersion time, the surface film became compact, and the corrosion rate of Mg/Ca composites slowed down. The surface film consisted mainly of CaCO(3), MgCO(3)x3H(2)O, HA and Mg(OH)(2) after 72 h immersion in DMEM. Mg/1Ca and Mg/5Ca composite extracts had no significant toxicity (p>0.05) to L-929 cells, whereas Mg/10Ca composite extract induced approximately 40% reduced cell viability. PMID:19815098

  19. Causal Factors of Weld Porosity in Gas Tungsten Arc Welding of Powder Metallurgy Produced Titanium Alloys

    SciTech Connect

    Muth, Thomas R [ORNL; Yamamoto, Yukinori [ORNL; Frederick, David Alan [ORNL; Contescu, Cristian I [ORNL; Chen, Wei [ORNL; Lim, Yong Chae [ORNL; Peter, William H [ORNL; Feng, Zhili [ORNL

    2013-01-01

    ORNL undertook an investigation using gas tungsten arc (GTA) welding on consolidated powder metallurgy (PM) titanium (Ti) plate, to identify the causal factors behind observed porosity in fusion welding. Tramp element compounds of sodium and magnesium, residual from the metallothermic reduction of titanium chloride used to produce the titanium, were remnant in the starting powder and were identified as gas forming species. PM-titanium made from revert scrap where sodium and magnesium were absent, showed fusion weld porosity, although to a lesser degree. We show that porosity was attributable to hydrogen from adsorbed water on the surface of the powders prior to consolidation. The removal / minimization of both adsorbed water on the surface of titanium powder and the residues from the reduction process prior to consolidation of titanium powders, are critical to achieve equivalent fusion welding success similar to that seen in wrought titanium produced via the Kroll process.

  20. Making Self-Lubricating Parts By Powder Metallurgy

    NASA Technical Reports Server (NTRS)

    Sliney, Harold E.; Dellacorte, Christopher

    1990-01-01

    Compositions and parameters of powder-metallurgical fabrication processes determined for new class of low-friction, low-wear, self-lubricating materials. Used in oxidizing or reducing atmospheres in bearings and seals, at temperatures from below 25 degrees C to as high as 900 degrees C. Thick parts made with minimal waste.

  1. A Nonvolume Preserving Plasticity Theory with Applications to Powder Metallurgy

    NASA Technical Reports Server (NTRS)

    Cassenti, B. N.

    1983-01-01

    A plasticity theory has been developed to predict the mechanical response of powder metals during hot isostatic pressing. The theory parameters were obtained through an experimental program consisting of hydrostatic pressure tests, uniaxial compression and uniaxial tension tests. A nonlinear finite element code was modified to include the theory and the results of themodified code compared favorably to the results from a verification experiment.

  2. Hydrogen halide cleaning of powder metallurgy nickel-20 chromium-3 thoria.

    NASA Technical Reports Server (NTRS)

    Herbell, T. P.

    1972-01-01

    The Cr2O3 content of powder metallurgy nickel-20 chromium-3 thoria was reduced with atmospheres consisting of hydrogen plus hydrogen chloride (HCl) or hydrogen bromide (HBr). The nonthoria oxygen content or 'oxygen excess' was reduced from an initial amount of greater than 50,000 ppm to less than 100 ppm. Low temperatures were effective, but lowest oxygen levels were achieved with the highest cleaning temperature of 1200 C.

  3. Recent development in the fabrication of metal matrix-particulate composites using powder metallurgy techniques

    Microsoft Academic Search

    Y. B. Liu; S. C. Lim; L. Lu; M. O. Lai

    1994-01-01

    It is advantageous to fabricate metal matrix-particulate composites (MMPCs) using powder metallurgy (PM) because the fabricated composites possess a higher dislocation density, a small sub-grain size and limited segregation of particles, which, when combined, result in superior mechanical properties. The various PM-related processes currently in use in the fabrication of MMPCs, are reviewed, outlining the common problems encountered in each

  4. An experimental determination of the thermal conductivity of a 304L stainless steel powder metallurgy material

    Microsoft Academic Search

    J. S. Agapiou; M. F. DeVries

    1989-01-01

    The thermal conductivity of a 304L stainless steel powder metallurgy (P\\/M) material was experimentally determined to support research aimed at understanding the poor machining characteristics of P\\/M austenitic stainless steels. Thermal conductivity measurements were made on samples having relative densities ranging between 64 and 90% of theoretical density since workpieces requiring machining are often fabricated in that density range. The

  5. Development of novel carbon nanotube reinforced magnesium nanocomposites using the powder metallurgy technique

    Microsoft Academic Search

    C S Goh; J Wei; L C Lee; M Gupta

    2006-01-01

    Carbon nanotube (CNT) reinforced magnesium was synthesized using the powder metallurgy technique followed by hot extrusion. Up to 0.3wt% of CNTs were added as reinforcements. The effects of the carbon nanotubes on the physical and mechanical properties of Mg were investigated. The thermo-mechanical property results show an increase in thermal stability with increasing amount of CNTs in the Mg nanocomposites.

  6. Micro powder metallurgy for the replicative production of metallic microstructures

    Microsoft Academic Search

    A. Rota; T. V. Duong; T. Hartwig

    2002-01-01

    Reproductive techniques like injection molding or embossing of feedstock provide microstructures of a wide variety of materials\\u000a for a reasonable price to micro system technology. In this paper, the dependencies and barriers to produce high aspect ratio\\u000a structures by micro metal injection molding are described; some results of embossing of metal powder based feedstocks are\\u000a presented, too. The investigations show

  7. Powder metallurgy processing of high strength turbine disk alloys

    NASA Technical Reports Server (NTRS)

    Evans, D. J.

    1976-01-01

    Using vacuum-atomized AF2-1DA and Mar-M432 powders, full-scale gas turbine engine disks were fabricated by hot isostatically pressing (HIP) billets which were then isothermally forged using the Pratt & Whitney Aircraft GATORIZING forging process. While a sound forging was produced in the AF2-1DA, a container leak had occurred in the Mar-M432 billet during HIP. This resulted in billet cracking during forging. In-process control procedures were developed to identify such leaks. The AF2-1DA forging was heat treated and metallographic and mechanical property evaluation was performed. Mechanical properties exceeded those of Astroloy, one of the highest temperature capability turbine disk alloys presently used.

  8. Accelerated Near-Threshold Fatigue Crack Growth Behavior of an Aluminum Powder Metallurgy Alloy

    NASA Technical Reports Server (NTRS)

    Piascik, Robert S.; Newman, John A.

    2002-01-01

    Fatigue crack growth (FCG) research conducted in the near threshold regime has identified a room temperature creep crack growth damage mechanism for a fine grain powder metallurgy (PM) aluminum alloy (8009). At very low DK, an abrupt acceleration in room temperature FCG rate occurs at high stress ratio (R = Kmin/Kmax). The near threshold accelerated FCG rates are exacerbated by increased levels of Kmax (Kmax less than 0.4 KIC). Detailed fractographic analysis correlates accelerated FCG with the formation of crack-tip process zone micro-void damage. Experimental results show that the near threshold and Kmax influenced accelerated crack growth is time and temperature dependent.

  9. Joining of rapidly solidified powder metallurgy Al-Fe-Ce alloys

    SciTech Connect

    Baeslack, W.A. III

    1989-01-01

    Joining of rapidly-solidified powder metallurgy (RS/PM) Al-Fe-Ce alloys by capacitor-discharge and inertia-friction welding investigated from a metallurgical perspective. Capacitor-discharge welding was effective in the joining of 6.4 mm diameter Al-8Fe-4Ce rod. The application of pressure simultaneously with fusion zone solidification suppressed the formation of fusion zone porosity in this high-hydrogen PM product. In addition, extremely rapid cooling rates promoted RS fusion zone microstructures and prevented heat-affected zone (HAZ) formation, thereby providing joint efficiencies up to 100%. 4 references, 9 figures, 2 tables.

  10. Electrochemical study of Aluminum-Fly Ash composites obtained by powder metallurgy

    SciTech Connect

    Marin, E. [Department of Chemistry, Physics and Environment, University of Udine, Via Cotonificio 108, 33100, Udine (Italy); Lekka, M., E-mail: maria.lekka@uniud.it [Department of Chemistry, Physics and Environment, University of Udine, Via Cotonificio 108, 33100, Udine (Italy); Andreatta, F.; Fedrizzi, L. [Department of Chemistry, Physics and Environment, University of Udine, Via Cotonificio 108, 33100, Udine (Italy); Itskos, G. [School of Chemical Engineering, National Technical University of Athens, Iroon Polytechneiou 9, Zografou 15780, Athens (Greece); Centre for Research and Technology Hellas/Institute for Solid Fuels Technology and Applications, Mesogeion Avenue 357-359, Halandri 15231, Athens (Greece); Moutsatsou, A. [School of Chemical Engineering, National Technical University of Athens, Iroon Polytechneiou 9, Zografou 15780, Athens (Greece); Koukouzas, N. [Centre for Research and Technology Hellas/Institute for Solid Fuels Technology and Applications, Mesogeion Avenue 357-359, Halandri 15231, Athens (Greece); Kouloumbi, N. [School of Chemical Engineering, National Technical University of Athens, Iroon Polytechneiou 9, Zografou 15780, Athens (Greece)

    2012-07-15

    In this paper, two different ASTM C 618 Class C fly ashes (FA) were used for the production of aluminum metal matrix composites (MMCs) using powder metallurgy (PM) technology. Calcareous FAs were sampled from the electrostatic precipitators of two different lignite-fired power stations: from Megalopolis, Southern Greece (MFA) and from Kardia, Northen Greece (KFA), under maximum electricity load. FAs were milled in order to reduce the mean particle diameter and Aluminum-FA composites containing 10% and 20% of FA were then prepared and compacted. The green products were sintered for 2 h at 600 Degree-Sign C. Sintered Al-FA MMCs showed increased hardness and wear resistance suggesting their possible use in industrial applications for example in covers, casings, brake rotors or engine blocks. As most possible industrial applications of MMCs not only require wear resistance, but also corrosion resistance in different mild aggressive medias, this paper aims to study the electrochemical behavior of FA MMCs in order to evaluate their corrosion resistance. The morphology and chemical composition of the phases in the Aluminum-FA composite samples were investigated using Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDXS). Moreover, topographic and Volta potential maps were acquired by Scanning Kelvin Probe Force Microscopy (SKP-FM). Volta potential maps provide information about the electrochemical behavior of the different phases in absence of electrolyte. The electrochemical behavior was investigated by Open Circuit Potential measurements and potentiodynamic polarization, while the corrosion mechanisms were studied by SEM observations after different times of immersion in a mild corrosive medium. In all cases it could be stated that the addition of the FA particles into the Al matrix might cause an increase of the hardness and mechanical properties of the pure aluminum but deteriorates the corrosion resistance. The degradation phenomena occurring on the FA containing samples might be related to the following mechanisms: 1) Partial detachment or dissolution of the FA soluble phases, in particular based on Si, Fe and Ca; 2) dissolution of the Al matrix surrounding the FA particles due to crevice corrosion; 3) Al localized dissolution due to galvanic coupling between the Fe-rich intermetallics and the matrix. - Highlights: Black-Right-Pointing-Pointer Aluminum metal matrix composites containing two types of fly ashes have been characterized. Black-Right-Pointing-Pointer The microstructure and the electrochemical behavior have been studied using different techniques. Black-Right-Pointing-Pointer The addition of FA deteriorates the corrosion resistance of the aluminum. Black-Right-Pointing-Pointer Degradation mechanisms: galvanic coupling, crevice corrosion, detachment of FA particles.

  11. The effect of sintering temperature on the mechanical properties of a Cu/CNT nanocomposite prepared via a powder metallurgy method

    NASA Astrophysics Data System (ADS)

    Trinh Pham, Van; Thang Bui, Hung; Tran, Bao Trung; Nguyen, Van Tu; Quang Le, Dinh; Tinh Than, Xuan; Chuc Nguyen, Van; Phuong Doan, Dinh; Phan, Ngoc Minh

    2011-03-01

    Metal matrix nanocomposites have become popular in industrial applications. Carbon nanotubes (CNTs), since theirs appearance, with their unique properties such as exceptionally small diameters and high Young's modulus, tensile strength and high chemical stability, are considered to be an attractive reinforcement material for lightweight and high-strength metallic matrix composites. The powder metallurgy method allows nanocomposite materials, notably metal–ceramic composites, to be produced by sintering a mixture of powders. In this study, we have utilized the powder metallurgy method to fabricate a Cu/CNT nanocomposite. Sintering is the important process in this method; it is the process whereby powder compacts are heated so that adjacent particles fuse together. The aim of this paper is to investigate the effect of sintering temperature on the mechanical properties of the Cu/CNT nanocomposite. The sintering temperature was in the range of 850–950?°C for 2?h. A correlation between the microstructure and mechanical properties, including the microstructure, density, hardness and compressive strength, is established. In this process, the density, and the physical and mechanical properties of the nanocomposites, can be changed, depending on the rate of sintering as well as the sintering temperature.

  12. Effects of fine porosity on the fatigue behavior of a powder metallurgy superalloy

    NASA Technical Reports Server (NTRS)

    Miner, R. V., Jr.; Dreshfield, R. L.

    1980-01-01

    Hot isostatically pressed powder metallurgy Astroloy was obtained which contained 1.4 percent fine porosity at the grain boundaries produced by argon entering the powder container during pressing. This material was tested at 650 C in fatigue, creep fatigue, tension, and stress-rupture and the results compared with previous data on sound Astroloy. The pores averaged about 2 micrometers diameter and 20 micrometers spacing. They did influence fatigue crack initiation and produced a more intergranular mode of propagation. However, fatigue life was not drastically reduced. A large 25 micrometers pore in one specimen resulting from a hollow particle did not reduce life by 60 percent. Fatigue behavior of the porous material showed typical correlation with tensile behavior. The plastic strain range life relation was reduced proportionately with the reduction in tensile ductility, but the elastic strain range-life relation was little changed reflecting the small reduction in sigma sub u/E for the porous material.

  13. Effects of fine porosity on the fatigue behavior of a powder metallurgy superalloy

    NASA Technical Reports Server (NTRS)

    Miner, R. V.; Dreshfield, R. L.

    1980-01-01

    Hot-isostatically-pressed powder-metallurgy Astroloy was obtained which contained 1.4 percent porosity at the grain boundaries produced by argon entering the powder container during pressing. This material was tested at 650 C in fatigue, creep-fatigue, tension, and stress-rupture and the results compared with data on sound Astroloy. They influenced fatigue crack initiation and produced a more intergranular mode of propagation but fatigue life was not drastically reduced. Fatigue behavior of the porous material showed typical correlation with tensile behavior. The plastic strain range-life relation was reduced proportionately with the reduction in tensile ductility, but the elastic strain range-life relation was changed little.

  14. Development of an extra-high strength powder metallurgy nickel-base superalloy

    NASA Technical Reports Server (NTRS)

    Kent, W. B.

    1977-01-01

    A program was conducted to optimize the composition of NASA IIb-11, an alloy originally developed as a wrought material, for thermal stability and to determine the feasibility for producing the alloy using powder metallurgy techniques. Seven compositions were melted and atomized, hot isostatically pressed, cross rolled to disks and heat treated. Tensile and stress rupture properties from room temperature to 870 C (1600 F) were determined in addition to thermal stability characteristics. Processing variables included hot isostatic pressing parameters and handling, cross rolling procedures and heat treatment cycles. NASA IIb-11E displayed the best combination of overall properties for service as a 760 C (1400 F) disk material. Its composition is 0.06 C, 8.5 Cr, 9.0 Co, 2.0 Mo, 7.1 W, 6.6 Ta, 4.5 Al, 0.75 Ti, 0.5 V, 0.7 Hf, 0.01 B, 0.05 Zr and balance Ni. While the alloy exhibits the highest 760 C (1400 F) rupture strength reported for any powder metallurgy disk alloy to date, additional studies to further evaluate the effects of heat treatment may be required. The alloy is not susceptible to topologically close-packed phase formation during thermal exposure at 870 C (1600 F) for 1,500 hours, but its mechanical property levels are lowered due to grain boundary carbide formation.

  15. Microstructural and mechanical characteristics of porous iron prepared by powder metallurgy.

    PubMed

    Capek, Jaroslav; Vojt?ch, Dalibor

    2014-10-01

    The demand for porous biodegradable load-bearing implants has been increasing recently. Based on investigations of biodegradable stents, porous iron may be a suitable material for such applications. In this study, we prepared porous iron samples with porosities of 34-51 vol.% by powder metallurgy using ammonium bicarbonate as a space-holder material. We studied sample microstructure (SEM-EDX and XRD), flexural and compressive behaviors (universal loading machine) and hardness HV5 (hardness tester) of the prepared samples. Sample porosity increased with the amount of spacer in the initial mixtures. Only the pore surfaces had insignificant oxidation and no other contamination was observed. Increasing porosity decreased the mechanical properties of the samples; although, the properties were still comparable with human bone and higher than those of porous non-metallic biomaterials and porous magnesium prepared in a similar way. Based on these results, powder metallurgy appears to be a suitable method for the preparation of porous iron for orthopedic applications. PMID:25175241

  16. Reduction and carburization in iron powder production at the brovary powder metallurgy factory

    Microsoft Academic Search

    A. F. Zhornyak; Yu. I. Timchenko; I. M. Fedorenko

    1968-01-01

    1.Study of the reduction and carburization kinetics in iron powder furnaces exposed and led to the removal of several shortcomings in these units.2.A method has been developed for reducing the charge in porous drip pans made from rolled powders. Trials using this method showed that the porous drip pans improve heat transfer and gas permeability of the charge and so

  17. Assessment of Low Cycle Fatigue Behavior of Powder Metallurgy Alloy U720

    NASA Technical Reports Server (NTRS)

    Gabb, Tomothy P.; Bonacuse, Peter J.; Ghosn, Louis J.; Sweeney, Joseph W.; Chatterjee, Amit; Green, Kenneth A.

    2000-01-01

    The fatigue lives of modem powder metallurgy disk alloys are influenced by variabilities in alloy microstructure and mechanical properties. These properties can vary as functions of variables the different steps of materials/component processing: powder atomization, consolidation, extrusion, forging, heat treating, and machining. It is important to understand the relationship between the statistical variations in life and these variables, as well as the change in life distribution due to changes in fatigue loading conditions. The objective of this study was to investigate these relationships in a nickel-base disk superalloy, U720, produced using powder metallurgy processing. Multiple strain-controlled fatigue tests were performed at 538 C (1000 F) at limited sets of test conditions. Analyses were performed to: (1) assess variations of microstructure, mechanical properties, and LCF failure initiation sites as functions of disk processing and loading conditions; and (2) compare mean and minimum fatigue life predictions using different approaches for modeling the data from assorted test conditions. Significant variations in life were observed as functions of the disk processing variables evaluated. However, the lives of all specimens could still be combined and modeled together. The failure initiation sites for tests performed at a strain ratio R(sub epsilon) = epsilon(sub min)/epsilon(sub max) of 0 were different from those in tests at a strain ratio of -1. An approach could still be applied to account for the differences in mean and maximum stresses and strains. This allowed the data in tests of various conditions to be combined for more robust statistical estimates of mean and minimum lives.

  18. Application of ANN in the prediction of the pore concentration of aluminum metal foams manufactured by powder metallurgy methods

    Microsoft Academic Search

    Sermin Ozan; Mustafa Taskin; Sedat Kolukisa; Mehmet Sirac Ozerdem

    2008-01-01

    In this work, the effect of fabrication parameters on the pore concentration of aluminum metal foam, manufactured by the powder\\u000a metallurgy process, has been studied. The artificial neural network (ANN) technique has been used to predict pore concentration\\u000a as a function of some key fabrication parameters. Aluminum metal foam specimens were fabricated from a mixture of aluminum\\u000a powders (mean particle

  19. Mechanisms of fatigue crack retardation following single tensile overloads in powder metallurgy aluminum alloys

    NASA Technical Reports Server (NTRS)

    Bray, G. H.; Reynolds, A. P.; Starke, E. A., Jr.

    1992-01-01

    In ingot metallurgy (IM) alloys, the number of delay cycles following a single tensile overload typically increases from a minimum at an intermediate baseline stress intensity range, Delta-K(B), with decreasing Delta-K(B) approaching threshold and increasing Delta-K(B) approaching unstable fracture to produce a characteristic 'U' shaped curve. Two models have been proposed to explain this behavior. One model is based on the interaction between roughness and plasticity-induced closure, while the other model only utilizes plasticity-induced closure. This article examines these models, using experimental results from constant amplitude and single overload fatigue tests performed on two powder metallurgy (PM) aluminum alloys, AL-905XL and AA 8009. The results indicate that the 'U'-shaped curve is primarily due to plasticity-induced closure, and that the plasticity-induced retardation effect is through-thickness in nature, occurring in both the surface and interior regions. However, the retardation effect is greater at the surface, because the increase in plastic strain at the crack tip and overload plastic zone size are larger in the plane-stress surface regions than in the plane-strain interior regions. These results are not entirely consistent with either of the proposed models.

  20. Accelerated Threshold Fatigue Crack Growth Effect-Powder Metallurgy Aluminum Alloy

    NASA Technical Reports Server (NTRS)

    Piascik, R. S.; Newman, J. A.

    2002-01-01

    Fatigue crack growth (FCG) research conducted in the near threshold regime has identified a room temperature creep crack growth damage mechanism for a fine grain powder metallurgy (PM) aluminum alloy (8009). At very low (Delta) K, an abrupt acceleration in room temperature FCG rate occurs at high stress ratio (R = K(sub min)/K(sub max)). The near threshold accelerated FCG rates are exacerbated by increased levels of K(sub max) (K(sub max) = 0.4 K(sub IC)). Detailed fractographic analysis correlates accelerated FCG with the formation of crack-tip process zone micro-void damage. Experimental results show that the near threshold and K(sub max) influenced accelerated crack growth is time and temperature dependent.

  1. Corrosion Resistance of Powder Metallurgy Processed TiC/316L Composites with Mo Additions

    NASA Astrophysics Data System (ADS)

    Lin, Shaojiang; Xiong, Weihao

    2015-06-01

    To find out the effects of Mo addition on corrosion resistance of TiC/316L stainless steel composites, TiC/316L composites with addition of different contents of Mo were prepared by powder metallurgy. The corrosion resistance of these composites was evaluated by the immersion tests and polarization curves experiments. Results indicated that Mo addition decreased the corrosion rates of TiC/316L composites in H2SO4 solution in the case of Mo content below 2% whereas it displayed an opposite effect when Mo content was above that value. It was found that with an increase in the Mo content, the pitting corrosion resistance increased monotonically for TiC/316L composites in NaCl solution.

  2. Novelties in physics of explosive welding and powder compaction

    Microsoft Academic Search

    I. Plaksin; J. Campos; J. Ribeiro; R. Mendes; J. Direito; D. Braga; R. Pruemmer

    2003-01-01

    Widely known technologies of explosive (X) welding and explosive (X) powder compaction are based on applications of porous composite solid or liquid explosives. Recent results on dynamics of X-welding and X-powder compaction are presented and discussed in this paper in the conceptual context of an orderly oscillating detonation wave (DW), a synergetic phenomenon observed in detonation of all classes of

  3. Niobium-titanium superconductors produced by powder metallurgy having artificial flux pinning centers

    DOEpatents

    Jablonski, Paul D. (Madison, WI); Larbalestier, David C. (Madison, WI)

    1993-01-01

    Superconductors formed by powder metallurgy have a matrix of niobium-titanium alloy with discrete pinning centers distributed therein which are formed of a compatible metal. The artificial pinning centers in the Nb-Ti matrix are reduced in size by processing steps to sizes on the order of the coherence length, typically in the range of 1 to 10 nm. To produce the superconductor, powders of body centered cubic Nb-Ti alloy and the second phase flux pinning material, such as Nb, are mixed in the desired percentages. The mixture is then isostatically pressed, sintered at a selected temperature and selected time to produce a cohesive structure having desired characteristics without undue chemical reaction, the sintered billet is reduced in size by deformation, such as by swaging, the swaged sample receives heat treatment and recrystallization and additional swaging, if necessary, and is then sheathed in a normal conducting sheath, and the sheathed material is drawn into a wire. The resulting superconducting wire has second phase flux pinning centers distributed therein which provide enhanced J.sub.ct due to the flux pinning effects.

  4. Feasibility study of the production of biomedical Ti-6Al-4V alloy by powder metallurgy.

    PubMed

    Bolzoni, L; Ruiz-Navas, E M; Gordo, E

    2015-04-01

    Titanium and its alloys are characterized by an exceptional combination of properties like high strength, good corrosion resistance and biocompatibility which makes them suitable materials for biomedical prosthesis and devices. The wrought Ti-6Al-4V alloy is generally favored in comparison to other metallic biomaterials due to its relatively low elastic modulus and it has been long used to obtain products for biomedical applications. In this work an alternative route to fabricate biomedical implants made out of the Ti-6Al-4V alloy is investigated. Specifically, the feasibility of the conventional powder metallurgy route of cold uniaxial pressing and sintering is addressed by considering two types of powders (i.e. blended elemental and prealloyed). The characterization of physical properties, chemical analysis, mechanical behavior and microstructural analysis is carried out in-depth and the properties are correlated among them. On the base of the results found, the produced alloys are promising materials for biomedical applications as well as cheaper surgical devices and tools. PMID:25686965

  5. Powder Metallurgy of Uranium Alloy Fuels for TRU-Burning Reactors Final Technical Report

    SciTech Connect

    Sean M. McDeavitt

    2011-04-29

    Overview Fast reactors were evaluated to enable the transmutation of transuranic isotopes generated by nuclear energy systems. The motivation for this was that TRU isotopes have high radiotoxicity and relatively long half-lives, making them unattractive for disposal in a long-term geologic repository. Fast reactors provide an efficient means to utilize the energy content of the TRUs while destroying them. An enabling technology that requires research and development is the fabrication metallic fuel containing TRU isotopes using powder metallurgy methods. This project focused upon developing a powder metallurgical fabrication method to produce U-Zr-transuranic (TRU) alloys at relatively low processing temperatures (500ºC to 600ºC) using either hot extrusion or alpha-phase sintering for charecterization. Researchers quantified the fundamental aspects of both processing methods using surrogate metals to simulate the TRU elements. The process produced novel solutions to some of the issues relating to metallic fuels, such as fuel-cladding chemical interactions, fuel swelling, volatility losses during casting, and casting mold material losses. Workscope There were two primary tasks associated with this project: 1. Hot working fabrication using mechanical alloying and extrusion • Design, fabricate, and assemble extrusion equipment • Extrusion database on DU metal • Extrusion database on U-10Zr alloys • Extrusion database on U-20xx-10Zr alloys • Evaluation and testing of tube sheath metals 2. Low-temperature sintering of U alloys • Design, fabricate, and assemble equipment • Sintering database on DU metal • Sintering database on U-10Zr alloys • Liquid assisted phase sintering on U-20xx-10Zr alloys Appendices Outline Appendix A contains a Fuel Cycle Research & Development (FCR&D) poster and contact presentation where TAMU made primary contributions. Appendix B contains MSNE theses and final defense presentations by David Garnetti and Grant Helmreich outlining the beginning of the materials processing setup. Also included within this section is a thesis proposal by Jeff Hausaman. Appendix C contains the public papers and presentations introduced at the 2010 American Nuclear Society Winter Meeting. Appendix A—MSNE theses of David Garnetti and Grant Helmreich and proposal by Jeff Hausaman A.1 December 2009 Thesis by David Garnetti entitled “Uranium Powder Production Via Hydride Formation and Alpha Phase Sintering of Uranium and Uranium-Zirconium Alloys for Advanced Nuclear Fuel Applications” A.2 September 2009 Presentation by David Garnetti (same title as document in Appendix B.1) A.3 December 2010 Thesis by Grant Helmreich entitled “Characterization of Alpha-Phase Sintering of Uranium and Uranium-Zirconium Alloys for Advanced Nuclear Fuel Applications” A.4 October 2010 Presentation by Grant Helmreich (same title as document in Appendix B.3) A.5 Thesis Proposal by Jeffrey Hausaman entitled “Hot Extrusion of Alpha Phase Uranium-Zirconium Alloys for TRU Burning Fast Reactors” Appendix B—External presentations introduced at the 2010 ANS Winter Meeting B.1 J.S. Hausaman, D.J. Garnetti, and S.M. McDeavitt, “Powder Metallurgy of Alpha Phase Uranium Alloys for TRU Burning Fast Reactors,” Proceedings of 2010 ANS Winter Meeting, Las Vegas, Nevada, USA, November 7-10, 2010 B.2 PowerPoint Presentation Slides from C.1 B.3 G.W. Helmreich, W.J. Sames, D.J. Garnetti, and S.M. McDeavitt, “Uranium Powder Production Using a Hydride-Dehydride Process,” Proceedings of 2010 ANS Winter Meeting, Las Vegas, Nevada, USA, November 7-10, 2010 B.4. PowerPoint Presentation Slides from C.3 B.5 Poster Presentation from C.3 Appendix C—Fuel cycle research and development undergraduate materials and poster presentation C.1 Poster entitled “Characterization of Alpha-Phase Sintering of Uranium and Uranium-Zirconium Alloys” presented at the Fuel Cycle Technologies Program Annual Meeting C.2 April 2011 Honors Undergraduate Thesis by William Sames, Research Fellow, entitled “Uranium Metal Powder Production, Particle Dis

  6. Understanding the strength of hot-pressed nanostructured powder compacts

    SciTech Connect

    Rawers, J.C. [Dept. of Energy, Albany, OR (United States). Albany Research Center] [Dept. of Energy, Albany, OR (United States). Albany Research Center; Harlow, D.G. [Lehigh Univ., Bethlehem, PA (United States)] [Lehigh Univ., Bethlehem, PA (United States)

    1999-02-01

    Attrition-milled nanostructured powders were hot pressed, and macroscopic properties of density, hardness, grain size, and strength were measured. No correlation was found between processing conditions (temperature and time) used in this study and compact properties, nor was a correlation found between the tensile (or failure) stress and density, hardness, or grain size. Variations of compact properties of unmilled powder were similar to that of milled powders. Tensile data were not well fitted to a Gaussian distribution but were well fitted to a two-parameter Weibull distribution. Thus, although the milled powder compacts had an average tensile strength greater than the unmilled powder compacts, all sample compositions fit a distribution with zero as a possible minimal stress level. Weibull analysis suggests that the tensile and compression strength is controlled by the presence of fine cracks, which may limit future engineering applications. Efforts to eliminate these cracks during hot pressing were unsuccessful.

  7. Dry wear behaviour and its relation to microstructure of novel 6092 aluminium alloy–Ni 3Al powder metallurgy composite

    Microsoft Academic Search

    Y. Wang; W. M. Rainforth; H. Jones; M. Lieblich

    2001-01-01

    Novel aluminium alloy matrix composites reinforced by 15vol.% Ni3Al intermetallic particles were prepared by a powder metallurgy route. The 6092 aluminium alloy was produced by gas atomisation, followed by blending with Ni3Al particles. Consolidation by extrusion at 515°C, with an extrusion ratio of 30:1, produced a uniform distribution of Ni3Al in the Al alloy matrix. The wear properties of the

  8. Laser photothermal non-destructive metrology of cracks in un-sintered powder metallurgy manufactured automotive transmission sprockets

    Microsoft Academic Search

    J. Tolev; A. Mandelis

    2010-01-01

    A non-contact and non-intrusive method of revealing crack presence in un-sintered (green) automotive transmission parts (sprockets), manufactured by means of a powder metallurgy technology based on analysis of photo-thermal radiometric (PTR) signals and their statistical analysis was developed. The inspection methodology relies on the interaction of a modulated laser generated thermal wave with the potential crack and the resulting change

  9. Artificial neural network model in surface modification by EDM using tungsten–copper powder metallurgy sintered electrodes

    Microsoft Academic Search

    Promod Kumar Patowari; Partha Saha; P. K. Mishra

    2010-01-01

    Electro-discharge machining (EDM) is a widely accepted nontraditional machining process used mostly for machining materials\\u000a difficult to machine by conventional shearing process. Surface modification by powder metallurgy sintered tools is an uncommon\\u000a aspect of EDM. Of late, it is being explored by many researchers. In the present paper, attempts have been made to model the\\u000a surface modification phenomenon by EDM

  10. Constitutive equations for creep and plasticity of aluminum alloys produced by powder metallurgy and aluminum-based metal matrix composites

    Microsoft Academic Search

    E. Evangelista; S. Spigarelli

    2002-01-01

    The constitutive relationships between stress, strain rate, and temperature were analyzed to obtain a unified description\\u000a of creep and plasticity of aluminum alloys produced by powder metallurgy and of aluminum-based metal-matrix composites. As\\u000a both classes of materials are characterized by the existence of a threshold stress (?\\u000a 0), a unified description of creep (low strain-rate regime) and plasticity (high strain-rate

  11. Application of powder metallurgy technique to produce improved bearing elements for cryogenic aerospace engine turbopumps

    NASA Technical Reports Server (NTRS)

    Moxson, V. S.; Moracz, D. J.; Bhat, B. N.; Dolan, F. J.; Thom, R.

    1987-01-01

    Traditionally, vacuum melted 440C stainless steel is used for high performance bearings for aerospace cryogenic systems where corrosion due to condensation is a major concern. For the Space Shuttle Main Engine (SSME), however, 440C performance in the high-pressure turbopumps has been marginal. A basic assumption of this study was that powder metallurgy, rather than cast/wrought, processing would provide the finest, most homogeneous bearing alloy structure. Preliminary testing of P/M alloys (hardness, corrosion resistance, wear resistance, fatigue resistance, and fracture toughness) was used to 'de-select' alloys which did perform as well as baseline 440C. Five out of eleven candidate materials (14-4/6V, X-405, MRC-2001, T-440V, and D-5) based on preliminary screening were selected for the actual rolling-sliding five-ball testing. The results of this test were compared with high-performance vacuum-melted M50 bearing steel. The results of the testing indicated outstanding performance of two P/M alloys, X-405 and MRC-2001, which eventually will be further evaluated by full-scale bearing testing.

  12. Creep behavior of an aluminum 2024 alloy produced by powder metallurgy

    SciTech Connect

    Kloc, L.; Spigarelli, S.; Cerri, E.; Evangelista, E. [Univ. of Ancona (Italy). Dept. of Mechanics] [Univ. of Ancona (Italy). Dept. of Mechanics; Langdon, T.G. [Univ. of Southern California, Los Angeles, CA (United States)] [Univ. of Southern California, Los Angeles, CA (United States)

    1997-02-01

    Creep tests were conducted over a range of temperatures from 523 to 603 K on an unreinforced 2024 Al alloy fabricated by powder metallurgy processing. The creep curves under all testing conditions exhibit a brief quasi-steady-state condition and then a very extended tertiary stage leading to failure. A logarithmic plot of the minimum creep rate against the applied stress leads to a high and variable stress exponent and a high apparent activation energy. Prior to creep testing, the specimens contained large particles identified as Al{sub 2}Cu and Al{sub 2}CuMg. A precipitation of fine particles occurred during testing; this was especially evident in the long-term tests at the highest testing temperature. An analysis of the creep data is developed based on incorporating a threshold stress into the creep equation and using measurements of particle densities in order to include the influence of continuous precipitation during testing. The significance of the threshold stress is examined, and it is shown that the analysis leads to a stress exponent of 5 and an activation energy approximately equal to the value for lattice self-diffusion in pure aluminum.

  13. A Novel Ni-Containing Powder Metallurgy Steel with Ultrahigh Impact, Fatigue, and Tensile Properties

    NASA Astrophysics Data System (ADS)

    Wu, Ming-Wei; Shu, Guo-Jiun; Chang, Shih-Ying; Lin, Bing-Hao

    2014-08-01

    The impact toughness of powder metallurgy (PM) steel is typically inferior, and it is further impaired when the microstructure is strengthened. To formulate a versatile PM steel with superior impact, fatigue, and tensile properties, the influences of various microstructures, including ferrite, pearlite, bainite, and Ni-rich areas, were identified. The correlations between impact toughness with other mechanical properties were also studied. The results demonstrated that ferrite provides more resistance to impact loading than Ni-rich martensite, followed by bainite and pearlite. However, Ni-rich martensite presents the highest transverse rupture strength (TRS), fatigue strength, tensile strength, and hardness, followed by bainite, pearlite, and ferrite. With 74 pct Ni-rich martensite and 14 pct bainite, Fe-3Cr-0.5Mo-4Ni-0.5C steel achieves the optimal combination of impact energy (39 J), TRS (2170 MPa), bending fatigue strength at 2 × 106 cycles (770 MPa), tensile strength (1323 MPa), and apparent hardness (38 HRC). The impact energy of Fe-3Cr-0.5Mo-4Ni-0.5C steel is twice as high as those of the ordinary high-strength PM steels. These findings demonstrate that a high-strength PM steel with high-toughness can be produced by optimized alloy design and microstructure.

  14. The substitution of nickel for cobalt in hot isostatically pressed powder metallurgy UDIMET 700 alloys

    NASA Technical Reports Server (NTRS)

    Harf, F. H.

    1985-01-01

    Nickel was substituted in various proportions for cobalt in a series of five hot-isostatically-pressed powder metallurgy alloys based on the UDIMET 700 composition. These alloys were given 5-step heat treatments appropriate for use in turbine engine disks. The resultant microstructures displayed three distinct sizes of gamma-prime particles in a gamma matrix. The higher cobalt-content alloys contained larger amounts of the finest gamma-prime particles, and had the lowest gamma-gamma-prime lattice mismatch. While all alloys had approximately the same tensile properties at 25 and 650 gamma C, the rupture lives at 650 and 760 C peaked in the alloys with cobalt contents between 12.7 and 4.3 pct. Minimum creep rates increased as cobalt contents were lowered, suggesting their correlation with the gamma-prime particle size distribution and the gamma-gamma-prime mismatch. It was also found that, on overaging at temperatures higher than suitable for turbine disk use, the high cobalt-content alloys were prone to sigma phase formation.

  15. Dwell Notch Low Cycle Fatigue Behavior of a Powder Metallurgy Nickel Disk Alloy

    NASA Technical Reports Server (NTRS)

    Telesman, J.; Gabb, T. P.; Yamada, Y.; Ghosn, L. J.; Jayaraman, N.

    2012-01-01

    A study was conducted to determine the processes which govern dwell notch low cycle fatigue (NLCF) behavior of a powder metallurgy (P/M) ME3 disk superalloy. The emphasis was placed on the environmentally driven mechanisms which may embrittle the highly stressed notch surface regions and reduce NLCF life. In conjunction with the environmentally driven notch surface degradation processes, the visco-plastic driven mechanisms which can significantly change the notch root stresses were also considered. Dwell notch low cycle fatigue testing was performed in air and vacuum on a ME3 P/M disk alloy specimens heat treated using either a fast or a slow cooling rate from the solutioning treatment. It was shown that dwells at the minimum stress typically produced a greater life debit than the dwells applied at the maximum stress, especially for the slow cooled heat treatment. Two different environmentally driven failure mechanisms were identified as the root cause of early crack initiation in the min dwell tests. Both of these failure mechanisms produced mostly a transgranular crack initiation failure mode and yet still resulted in low NLCF fatigue lives. The lack of stress relaxation during the min dwell tests produced higher notch root stresses which caused early crack initiation and premature failure when combined with the environmentally driven surface degradation mechanisms. The importance of environmental degradation mechanisms was further highlighted by vacuum dwell NLCF tests which resulted in considerably longer NLCF lives, especially for the min dwell tests.

  16. Tribological properties of PM212: A high-temperature, self-lubricating, powder metallurgy composite

    NASA Technical Reports Server (NTRS)

    Dellacorte, Christopher; Sliney, Harold E.

    1989-01-01

    This paper describes a research program to develop and evaluate a new high temperature, self-lubricating powder metallurgy composite, PM212. PM212 has the same composition as the plasma-sprayed coating, PS212, which contains 70 wt percent metal-bonded chromium carbide, 15 wt percent silver and 15 wt percent barium fluoride/calcium fluoride eutectic. The carbide acts as a wear resistant matrix and the silver and fluorides act as low and high temperature lubricants, respectively. The material is prepared by sequential cold press, cold isostatic pressing and sintering techniques. In this study, hemispherically tipped wear pins of PM212 were prepared and slid against superalloy disks at temperatures from 25 to 850 C in air in a pin-on-disk tribometer. Friction coefficients range from 0.29 to 0.38 and the wear of both the composite pins and superalloy disks was moderate to low in the 10(exp -5) to 10(exp -6) cubic mm/N-m range. Preliminary tests indicate that the material has a compressive strength of at least 130 MPa over the entire temperature range of 25 to 900 C. This material has promise for use as seal inserts, bushings, small inside diameter parts and other applications where plasma-sprayed coatings are impractical or too costly.

  17. Tribological properties of PM212 - A high temperature, self-lubricating, powder metallurgy composite

    NASA Technical Reports Server (NTRS)

    Dellacorte, Christopher; Sliney, Harold E.

    1990-01-01

    This paper describes a research program to develop and evaluate a new high temperature, self-lubricating powder metallurgy composite, PM212. PM212 has the same composition as the plasma-sprayed coating, PS212, which contains 70 wt percent metal-bonded chromium carbide, 15 wt percent silver and 15 wt percent barium fluoride/calcium fluoride eutectic. The carbide acts as a wear resistant matrix and the silver and fluorides act as low and high temperature lubricants, respectively. The material is prepared by sequential cold press, cold isostatic pressing and sintering techniques. In this study, hemispherically tipped wear pins of PM212 were prepared and slid against superalloy disks at temperatures from 25 to 850 C in air in a pin-on-disk tribometer. Friction coefficients range from 0.29 to 0.38 and the wear of both the composite pins and superalloy disks was moderate to low in the 10(exp -5) to 10(exp -6) cubic mm/N-m range. Preliminary tests indicate that the material has a compressive strength of at least 130 MPa over the entire temperature range of 25 to 900 C. This material has promise for use as seal inserts, bushings, small inside diameter parts and other applications where plasma-sprayed coatings are impractical or too costly.

  18. Copper-Carbon and Aluminum-Carbon Composites Fabricated by Powder Metallurgy Processes

    NASA Astrophysics Data System (ADS)

    Silvain, Jean-François; Veillère, Amélie; Lu, Yongfeng

    2014-07-01

    The increase in both power and packing densities in power electronic devices has led to an increase in the market demand for effective heat-dissipating materials, with high thermal conductivity and thermal- expansion coefficient compatible with chip materials still ensuring the reliability of the power modules. In this context, metal matrix composites: carbon fibers and diamond-reinforced copper and aluminum matrix composites among them are considered very promising as a next generation of thermal-management materials in power electronic packages. These composites exhibit enhanced thermal properties compared to pure copper combined with lower density. This article presents the fabrication techniques of copper/carbon fibers and copper/diamond and aluminum/carbon fibers composite films by powder metallurgy and hot pressing. The thermal analyses clearly indicate that interfacial treatments are required in these composites to achieve high thermomechanical properties. Interfaces (through novel chemical and processing methods), when selected carefully and processed properly will form the right chemical/mechanical link between metal and carbon, enhancing all the desired thermal properties while minimizing the deleterious effect.

  19. Analysis of powder compaction process through equal channel angular extrusion 

    E-print Network

    Kaushik, Anshul

    2009-05-15

    A thermodynamic framework was presented for the development of powderconstitutive models. The process of powder compaction through Equal ChannelAngular Extrusion (ECAE) at room temperature was modeled using the finiteelement ...

  20. Microwave Heating, Isothermal Sintering, and Mechanical Properties of Powder Metallurgy Titanium and Titanium Alloys

    NASA Astrophysics Data System (ADS)

    Luo, S. D.; Guan, C. L.; Yang, Y. F.; Schaffer, G. B.; Qian, M.

    2013-04-01

    This article presents a detailed assessment of microwave (MW) heating, isothermal sintering, and the resulting tensile properties of commercially pure Ti (CP-Ti), Ti-6Al-4V, and Ti-10V-2Fe-3Al (wt pct), by comparison with those fabricated by conventional vacuum sintering. The potential of MW sintering for titanium fabrication is evaluated accordingly. Pure MW radiation is capable of heating titanium powder to ?1573 K (1300 °C), but the heating response is erratic and difficult to reproduce. In contrast, the use of SiC MW susceptors ensures rapid, consistent, and controllable MW heating of titanium powder. MW sintering can consolidate CP-Ti and Ti alloys compacted from -100 mesh hydride-dehydride (HDH) Ti powder to ~95.0 pct theoretical density (TD) at 1573 K (1300 °C), but no accelerated isothermal sintering has been observed over conventional practice. Significant interstitial contamination occurred from the Al2O3-SiC insulation-susceptor package, despite the high vacuum used (?4.0 × 10-3 Pa). This leads to erratic mechanical properties including poor tensile ductility. The use of Ti sponge as impurity (O, N, C, and Si) absorbers can effectively eliminate this problem and ensure good-to-excellent tensile properties for MW-sintered CP-Ti, Ti-10V-2Fe-3Al, and Ti-6Al-4V. The mechanisms behind various observations are discussed. The prime benefit of MW sintering of Ti powder is rapid heating. MW sintering of Ti powder is suitable for the fabrication of small titanium parts or titanium preforms for subsequent thermomechanical processing.

  1. Processing and development of aluminum-silicon powder metallurgy alloys for hot forging technologies

    NASA Astrophysics Data System (ADS)

    Mosher, Winston G. E.

    The growing field of aluminum powder metallurgy (PM) brings promise to an economical and environmental demand for the production of high strength, light weight aluminum engine components. To tackle the limited selection of readily available light alloy blends, an experimental hypoeutectic AlSi alloy was chosen for study. The optimal processing route for this alloy was determined and the mechanical properties were examined. In an effort to further enhance the mechanical properties of the alloys, post sinter forging was investigated. This body of work consists of an introduction to relevant topics in PM, aluminum alloys, and forging followed by three sections of results and discussion. Each represents an accepted or submitted Journal Manuscript intended for journal publication. These sections deliver detailed experimental procedures, results and discussion for the development of the experimental PM alloy Al-65i, a comparison of hot deformation behaviours of Al-65i and Alumix-231 Al5i PM alloys, and their mechanical properties observed upon hot densification. A final section was added to summarize the important findings from each experiment. In the development of Al-65i, the alloy was able to achieve a high sintered density approaching 98%, and a yield strength of 232 MPa in the T6 condition. Upon hot upset forging, the experimental alloy achieved an average density of 99.6% (+/- 0.2%) while the commercial alloy (Alumix-231) achieved 98.3% (+/- 0.6%) of its theoretical density. It was found that the experimentally obtained peak flow stresses for each material studied could be very closely approximated using the semi-empirical Zener-Hollomon models. Upon hot densification it was found that all the mechanical properties of the Al-65i alloy were significantly enhanced. However, due to the fracturing of 5i particles during deformation, Alumix-231 experienced a reduction in density and UT5, while making improvements in ductility.

  2. Controlled powder morphology experiments in megabar 304 stainless steel compaction

    SciTech Connect

    Staudhammer, K.P.; Johnson, K.A.

    1985-01-01

    Experiments with controlled morphology including shape, size, and size distribution were made on 304L stainless steel powders. These experiments involved not only the powder variables but pressure variables of 0.08 to 1.0 Mbar. Also included are measured container strain on the material ranging from 1.5% to 26%. Using a new strain controllable design it was possible to seperate and control, independently, strain and pressure. Results indicate that powder morphology, size distribution, packing density are among the pertinent parameters in predicting compaction of these powders.

  3. Shock compression response of nanoiron powder compact

    NASA Astrophysics Data System (ADS)

    Dai, Chengda; Eakins, Daniel; Thadhani, Naresh; Liu, J. Ping

    2007-02-01

    The shock compression response of nano-Fe powder (˜25nm) pressed to ˜35% theoretical maximum density was determined based on shock stress and wave velocity measurements using piezoelectric stress gauges. The obtained data show a discontinuity in shock wave velocity plotted against particle velocity and an inflexion in specific volume from compression to expansion with increasing shock stress. It is found that the Hugoniot of 25nm Fe powder cannot be fully described using analytical models that are otherwise capable of predicting the Hugoniot of micron-sized powder or highly porous materials.

  4. Preparation of Cu and Fly Ash Composite by Powder Metallurgy Technique

    SciTech Connect

    Chew, P. Y.; Lim, P. S.; Ng, M. C. [Infineon Technologies (M) Sdn Bhd, Batu Berendam, 75450 Melaka (Malaysia); Zahi, S.; You, A. H. [Faculty of Engineering and Technology, Multimedia University, Jalan Ayer Keroh Lama, 75450 Melaka (Malaysia)

    2011-03-30

    Cu and Fly Ash (FA) mixtures with different weight percentages were prepared. Pellets of the mixture powder were produced with the dimension of 17.7 mm in diameter and 10-15 mm in height. These different composites were compacted at a constant pressure of 280 MPa. One of the selected weight percentages was then compacted to form into pellet and sintered at different temperatures which were at 900, 950 and 1000 deg. C respectively for 2 hours. Density of green pellet was measured before sintered in furnace. After sintering, all the pellets with different temperatures were re-weighed and sintered density were calculated. The densification of the green and sintered pellets was required to be measured as one of the parameter in selection of the best material properties. Porosity of the pellet shall not be ignored in order to analyze the close-packed particles stacking in the pellet. SEM micrograph had been captured to observe the presence of pores and agglomeration of particles in the sample produced.

  5. Warm compaction of attrition milled nanostructured iron powders

    SciTech Connect

    Rawers, J.

    1999-08-01

    Attrition milled, nanostructured iron-based powders were compacted at temperatures less than one-half the melting temperature and at pressure in excess of 2GPA and resulted in full dense samples from which macroscopic properties could be determined. The use of modest compaction temperatures results in (1) reducing the mechanical induced lattice strain, (2) producing interparticle bonding by grain boundary diffusion, and (3) limiting grain growth. The high compression stress resulted in deforming the milled particles into a fully dense compact. Hall-Petch relationships for the compacts were consistent with data from previous studies.

  6. Effects of Initial Powder Compact Thickness, Lubrication, and Particle Morphology on the Cold Compaction Behavior of Ti Powder

    NASA Astrophysics Data System (ADS)

    Lou, Jia; Gabbitas, Brian; Zhang, Deliang; Yang, Fei

    2015-05-01

    This work investigates the compaction behavior of hydride-dehydride CP-Ti powder from green density/compaction pressure curves. These were obtained through a modification of selected processing conditions, such as variation in compact thickness, the use of internal lubrication, and additions of plasma rotating electrode process powder. A modified Cooper-Eaton equation, which treats the compaction process to be a combination of particle rearrangement (PR) and plastic deformation (PD) mechanisms, was used to simulate the curves. A comparison with aluminum and iron compaction is also carried out in this study. The research indicated that the cold compaction of titanium powder can be separated into two stages: a PR stage (stage I), which occurs at a compacting pressure in the range of 0 to 200 MPa, followed by a further PR stage initiated by PD, when the compaction pressure is in the range of 200 to 1000 MPa. The existence of stage II is due to the low plastic deformability of titanium and low density achieved at the end of stage I.

  7. Dense and Homogeneous Compaction of Fine Ceramic and Metallic Powders: High-Speed Centrifugal Compaction Process

    NASA Astrophysics Data System (ADS)

    Suzuki, Hiroyuki Y.

    2008-02-01

    High-Speed Centrifugal Compaction Process (HCP) is a variation of colloidal compacting method, in which the powders sediment under huge centrifugal force. Compacting mechanism of HCP differs from conventional colloidal process such as slip casting. The unique compacting mechanism of HCP leads to a number of characteristics such as a higher compacting speed, wide applicability for net shape formation, flawless microstructure of the green compacts, etc. However, HCP also has several deteriorative characteristics that must be overcome to fully realize this process' full potential.

  8. Effect of sintering conditions on the microstructural and mechanical characteristics of porous magnesium materials prepared by powder metallurgy.

    PubMed

    ?apek, Jaroslav; Vojt?ch, Dalibor

    2014-02-01

    There has recently been an increased demand for porous magnesium materials in many applications, especially in the medical field. Powder metallurgy appears to be a promising approach for the preparation of such materials. Many works have dealt with the preparation of porous magnesium; however, the effect of sintering conditions on material properties has rarely been investigated. In this work, we investigated porous magnesium samples that were prepared by powder metallurgy using ammonium bicarbonate spacer particles. The effects of the purity of the argon atmosphere and sintering time on the microstructure (SEM, EDX and XRD) and mechanical behaviour (universal loading machine and Vickers hardness tester) of porous magnesium were studied. The porosities of the prepared samples ranged from 24 to 29 vol.% depending on the sintering conditions. The purity of atmosphere played a significant role when the sintering time exceeded 6h. Under a gettered argon atmosphere, a prolonged sintering time enhanced diffusion connections between magnesium particles and improved the mechanical properties of the samples, whereas under a technical argon atmosphere, oxidation at the particle surfaces caused deterioration in the mechanical properties of the samples. These results suggest that a refined atmosphere is required to improve the mechanical properties of porous magnesium. PMID:24411347

  9. Advances in powder metallurgy - 1991. Vol. 6 - Aerospace, refractory and advanced materials; Proceedings of the Powder Metallurgy Conference and Exhibition, Chicago, IL, June 9-12, 1991

    Microsoft Academic Search

    L. F. Pease; R. J. Sansoucy

    1991-01-01

    Various papers on aerospace, refractory, and advanced materials are presented. Individual topics addressed include: nonequilibrium processing of powder alloys for aerospace applications, chemical conditioning of rapidly solidified aluminum alloy particulate, fabrication of rapidly solidified high temperature aluminum alloys, fatigue and fracture of an advanced PM-aluminum alloy, thermal and mechanical properties of extruded 7075-Al P\\/M alloys, reactive sintering and reactive hot

  10. In situ preparation of titanium base composites reinforced by TiB single crystals using a powder metallurgy technique

    Microsoft Academic Search

    S Gorsse; J. P Chaminade; Y Le Petitcorps

    1998-01-01

    The feasibility of Ti\\/TiB composite by in situ precipitation of the reinforcement have been investigated. The titanium monoboride can be obtained by the chemical reaction between TiB2 and Ti powders. The fabrication method requires two stages: the first stage corresponds to the compacting of the pre-blended powders and the second one to the nucleation and growth of the TiB needles.

  11. Processing and microstructural evolution of powder metallurgy Zn-22 Pct Al eutectoid alloy containing nanoscale dispersion particles

    NASA Astrophysics Data System (ADS)

    Xun, Y.; Rodriguez, R.; Lavernia, E. J.; Mohamed, F. A.

    2005-10-01

    The present article deals with the processing and microstructural evolution of powder metallurgy (PM) Zn-22Al pct eutectoid alloy. The powder material was produced through inert gas atomization and then cryomilled in liquid nitrogen. The milled powder particles were consolidated by hot isostatic pressing (“hipping”) followed by thermomechanical treatment, resulting in a two-phase microstructure. The microstructures were characterized using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The principal processing factors and microstructural characteristics associated with the major processing steps, including spray atomization, mechanical milling (MM), consolidation, and heat treatment, were evaluated and discussed. Hot isostatic pressing and extrusion followed by heat treatment to produce the superplastic structure (Al-rich phase and Zn-rich phase) are effective in elimination porosity. A TEM examination of the microstructure of the alloy after processing reveals the presence of nanodispersion particles that are not uniformly distributed. The formation of the dispersions was attributed to the interaction between the powder material (primarily Al phase) and environmental elements such as oxygen and nitrogen during milling. Moreover, the size and distribution of the dispersions present in the bulk material met the anticipated requirements for serving as inhibitors for grain growth and barriers for dislocation movement. The TEM observations on crept specimens reveal extensive dislocation/dispersion interactions.

  12. A Process for Improved Induction Heating of Powder Metal Compacts

    Microsoft Academic Search

    Robert L. Conta

    1977-01-01

    An unusual ``incubation'' period is encountered at the beginning stages of medium frequency (3 kHz) induction heating of unsintered, low alloy, steel powder metal compacts. This incubation period is characterized by poor load coupling to the induction coil and consequently, very slow and inefficient heating. An unusually high material resistivity has been isolated as the cause of this incubation period.

  13. Static and Dynamic Compaction of CL-20 Powders

    NASA Astrophysics Data System (ADS)

    Cooper, Marcia A.; Brundage, Aaron L.; Dudley, Evan C.

    2009-12-01

    Hexanitrohexaazaisowurtzitane (CL-20) powders were compacted under quasi-static and dynamic loading conditions. A uniaxial compression apparatus quasi-statically compressed the powders to 90% theoretical maximum density with applied stresses up to 0.4 GPa. Dynamic compaction measurements using low-density pressings approximately 64% theoretical maximum density (TMD) were obtained in a single-stage gas gun at impact velocities between 0.17-0.95 km/s. Experiments were conducted in a reverse ballistic arrangement in which the projectile contained the CL-20 powder bed and impacted a target consisting of an aluminized window. VISAR-measured particle velocities at the explosive-window interface determined the shock Hugoniot states for pressures up to 1.3 GPa. Approved for public release, SAND2009-4810C.

  14. Using Microwave-Assisted Powder Metallurgy Route and Nano-size Reinforcements to Develop High-Strength Solder Composites

    NASA Astrophysics Data System (ADS)

    Nai, S. M. L.; Kuma, J. V. M.; Alam, M. E.; Zhong, X. L.; Babaghorbani, P.; Gupta, M.

    2010-04-01

    In the present study, Sn-0.7Cu and Sn-3.5Ag lead-free solders used in the electronics packaging industry were reinforced with different volume percentages of nano-size alumina and tin oxide particulates, respectively, to synthesize two new sets of nanocomposites. These composites were developed using microwave-assisted powder metallurgy route followed by extrusion. The effects of addition of particulates on the physical, microstructural, and mechanical properties of the nanocomposites were investigated. Mechanical properties (microhardness, 0.2% YS, and UTS) for both composite systems increase with the presence of particulates. The best tensile strength was realized for composite solders reinforced with 1.5 vol.% alumina and 0.7 vol.% tin oxide particulates, which far exceeds the strength of eutectic Sn-Pb solder. The morphology of pores was observed to be one of the most dominating factors affecting the strength of materials.

  15. Mechanical strength and thermophysical properties of PM212: A high temperature self-lubricating powder metallurgy composite

    NASA Technical Reports Server (NTRS)

    Edwards, Phillip M.; Sliney, Harold E.; Dellacorte, Christopher; Whittenberger, J. Daniel; Martineau, Robert R.

    1990-01-01

    A powder metallurgy composite, PM212, composed of metal bonded chromium carbide and solid lubricants is shown to be self-lubricating to a maximum application temperature of 900 C. The high temperature compressive strength, tensile strength, thermal expansion and thermal conductivity data needed to design PM212 sliding contact bearings and seals are reported for sintered and isostatically pressed (HIPed) versions of PM212. Other properties presented are room temperature density, hardness, and elastic modulus. In general, both versions appear to have adequate strength to be considered as sliding contact bearing materials, but the HIPed version, which is fully dense, is much stronger than the sintered version which contains about 20 percent pore volume. The sintered material is less costly to make, but the HIPed version is better where high compressive strength is important.

  16. A Novel Powder Metallurgy Processing Approach to Prepare Fine-Grained Cu-Al-Ni Shape-Memory Alloy Strips from Elemental Powders

    NASA Astrophysics Data System (ADS)

    Vajpai, S. K.; Dube, R. K.; Chatterjee, P.; Sangal, S.

    2012-07-01

    The current work describes the experimental results related to the successful preparation of fine-grained, Cu-Al-Ni, high-temperature shape-memory alloy (SMA) strips from elemental Cu, Al, and Ni powders via a novel powder metallurgy (P/M) processing approach. This route consists of short time period ball milling of elemental powder mixture, preform preparation from milled powder, sintering of preforms, hot-densification rolling of unsheathed sintered powder preforms under protective atmosphere, and postconsolidation homogenization treatment of the hot-rolled strips. It has been shown that it is possible to prepare chemically homogeneous Cu-Al-Ni SMA strips consisting of equiaxed grains of average size approximately 6 ?m via the current processing approach. It also has been shown that fine-grained microstructure in the finished Cu-Al-Ni SMA strips resulted from the pinning effect of nanosized alumina particles present on the grain boundaries. The finished SMA strips were almost fully martensitic in nature, consisting of a mixture of ?1^' } - and ?1^' } -type martensites. The Cu-Al-Ni SMA strips had 677 MPa average fracture strength, coupled with 13 pct average fracture strain. The fractured surfaces of the specimens exhibited primarily dimpled ductile type of fracture, together with some transgranular mode of fracture. The Cu-Al-Ni strips exhibited an almost 100 pct one-way shape recovery after bending followed by unconstrained heating at 1, 2, and 4 pct applied deformation prestrain. The two-way shape-memory strain was found approximately 0.35 pct after 15 training cycles at 4 pct applied training prestrain.

  17. Effects of MgO Nano Particles on Microstructural and Mechanical Properties of Aluminum Matrix Composite prepared via Powder Metallurgy Route

    NASA Astrophysics Data System (ADS)

    Baghchesara, Mohammad Amin; Abdizadeh, Hossein; Baharvandi, Hamid Reza

    The objective of the present investigation was to evaluate the microstructural and mechanical properties of Al/nano MgO composite prepared via powder metallurgy method. Pure atomized aluminum powder with an average particle size of 1?m and MgO particulate with an average particle size between 60 to 80 nm were used. Composites containing 1.5, 2.5 and 5 percent of volume fraction of MgO were prepared by powder metallurgy method. The specimens were pressed by Cold Isostatic Press machine (CIP), subsequently were sintered at 575, 600 and 625°C. After sintering and preparing the samples, mechanical properties were measured. The results of microstructure, compression and hardness tests indicated that addition of MgO particulates to aluminum matrix composites improves the mechanical properties.

  18. Complex Permittivity of Powder Metal Compacts by Cavity Perturbation Technique

    NASA Astrophysics Data System (ADS)

    Lynch, Chris; Johnson, Earnie; Ma, Junkun; Miskovsky, Nicholas; Weisel, Gary; Weiss, Brock; Zimmerman, Darin

    2006-03-01

    We present measurements of the complex permittivity of powder metal compacts using microwave cavity perturbation techniques. Using a 2.45GHz, TM010 microwave cavity operating in conjunction with a vector network analyzer, we have systematically measured the real (?') and imaginary (?'') parts of the effective complex permittivity of pure, powder metal, cylindrical samples (0.25in by 0.25in). By placing these in the electric-field antinode, the dielectric properties at microwave frequencies are obtained by comparison with the expected change in the cavity Q by perturbation theory. We have studied the effect of varying particle size and green density as means to understand the absorption and heating of powdered metals in microwave fields. We acknowledge the additional work of undergraduates Kelly Martin and Charles Smith, who assisted in the setup of experimental apparatus, sample preparation, and data acquisition.

  19. Static and Dynamic Compaction of CL-20 Powders

    NASA Astrophysics Data System (ADS)

    Cooper, Marcia; Brundage, Aaron; Dudley, Evan

    2009-06-01

    Hexanitrohexaazaisowurtzitane (CL-20) powders were compacted under quasi-static and dynamic loading conditions. A uniaxial compression apparatus quasi-statically compressed the powders to 90% theoretical maximum density with applied stresses up to 0.5 GPa. Dynamic compaction measurements using low-density pressings (62-70% theoretical maximum density) were obtained in a single-stage gas gun at impact velocities between 0.17-0.70 km/s. Experiments were conducted in a reverse ballistic arrangement in which the CL-20 ladened projectile impacted a target consisting of an aluminized window. VISAR-measured particle velocities at the explosive-window interface determined the shock Hugoniot states for pressures up to 0.9 GPa. The powder compaction behavior is found to be stiffer under dynamic loading than under quasi-static loading. Additional gas gun tests were conducted in which the low-density CL-20 pressings were confined within a target cup by the aluminized window. This arrangement enabled temporal measurement of the transmitted wave profiles in which elastic wave precursors were observed.

  20. Porous titanium obtained by a new powder metallurgy technique: Preliminary results of human osteoblast adhesion on surface polished substrates.

    PubMed

    Biasotto, M; Ricceri, R; Scuor, N; Schmid, C; Sandrucci, M A; Di Lenarda, R; Matteazzi, P

    2003-01-01

    This study concerns a novel powder metallurgy method for producing porous titanium (pTi) exhibiting high mechanical properties. The preparation procedure consisted of the following stages: first, the preparation of Ti and titanium hydride (TiH2) powder mixtures and their consolidation with a cold isostatic press, followed by a sintering of the green bodies performed with hot isostatic press (HIP) equipment. Thermal decomposition in controlled environment of the TiH2 phase results in the foam structure. The resulting porosity percolates with a volume fraction of approximately 20%. The final material exhibits interesting mechanical properties, comparable to those of full density titanium (between grade 2 and grade 3), with the advantage of a minor density. The samples produced were tested to verify their biological response by studying the effectiveness of osteoblast adhesion and growth. In this preliminary study, osteoblastic cell morphology was investigated and compared to that observed on fully dense commercially pure titanium (Ti-cp) (ASTM, grade 3). The preliminary results were promising regarding cellular adhesion and spreading. (Journal of Applied Biomaterials & Biomechanics 2003; 1: 172-7). PMID:20803454

  1. Processing and microstructure of powder metallurgy Al-Fe-Ni alloys

    NASA Astrophysics Data System (ADS)

    Premkumar, M. K.; Lawley, A.; Koczak, M. J.

    1992-12-01

    Prealloyed rapidly solidified Al-Fe-Ni alloy powder with dispersoid volume fractions of 0.19, 0.25, and 0.32 FeNiAl9 was produced by air atomization. The powder was degassed, canned, and consolidated to full density by vacuum hot pressing and extrusion or by direct extrusion. Microstructures in the alloy powder and consolidated material were characterized by means of optical, scanning (SEM), and transmission electron microscopy (TEM) and constituent phases identified by X-ray diffraction. The coarsening kinetics of the FeNiAl9 dispersoid were monitored by differential scanning calorimetry (DSC) and by quantitative metallography. Atomized powders exhibited two scales of microstructures: optically featureless regions and regions with a coarse dispersoid morphology. Within the featureless regions, there are three morphologies, namely, a fine uniform precipitate microstructure, a cellular microstructure, and an eutectic microstructure. The only dispersoid observed in the atomized powders and consolidated material was FeNiAl9. The two scales of microstructure were retained after consolidation, and after hot extrusion, the typical microstructure consisted of a recovered matrix structure with a grain size of 0.2 to 0.3 ?m and equiaxed intermetallics of average diameter 0.1 ?m. The microstructure was resistant to coarsening up to approximately 370 °C. Coarsening kinetics in this alloy system were consistent with a grain boundary diffusion model (activation energy 146 kJ/mol) and were not appreciably affected by dispersoid volume fraction.

  2. Thermal behavior of supersolidus bronze powder compacts during heating by hollow cathode discharge

    E-print Network

    dos Santos, C.A.

    Thermal behavior of supersolidus bronze powder compacts during heating by hollow cathode discharge Science B.V. Keywords: Supersolidus powder; AluminumÁ/bronze; Hollow cathode; Plasma heating 1 in the preparation of hyperfine powder [2], synthesis of new ceramics [3,4] and in the heat treatment of compacted

  3. Compressibility and compactibility of powdered polymers: poly(vinyl chloride) powders

    Microsoft Academic Search

    Anne-France Rime; Danielle Massuelle; Frank Kubel; Hans-Rudolf Hagemann; Eric Doelker

    1997-01-01

    The present investigation is concerned with the possible effects of material-related properties (molecular mass, glass transition and melting temperatures, crystallinity, tacticity) and particle-related properties (shape, size, specific surface area) on the compression characteristics of the chosen model polymer powder: poly(vinyl chloride) (PVC). Four grades were selected known in literature for providing compacts of varied mechanical strength. The compression characteristics were

  4. Towards an improved understanding of strength and anisotropy of cold compacted powder

    Microsoft Academic Search

    Wenhai Wang

    2007-01-01

    The strength of powder compacts after cold compaction is known to be anisotropic, which comes from the directionality of microstructure resulting from initial particle morphology and\\/or from particle deformation during compaction. Current work focuses on multi-scale numerical analysis of powder compaction with emphasis on the role of interparticle cohesion on post-compaction mechanical properties. At macroscopic level, we applied phenomenological model

  5. Development of superalloys by powder metallurgy for use at 1000 - 1400 F

    NASA Technical Reports Server (NTRS)

    Calhoun, C. D.

    1971-01-01

    Consolidated powders of four nickel-base superalloys were studied for potential application as compressor and turbine discs in jet engines. All of the alloys were based on the Rene' 95 chemistry. Three of these had variations in carbon and A12O3 contents, and the fourth alloy was chemically modified to a higher volume fraction. The A12O3 was added by preoxidation of the powders prior to extrusion. Various levels of four experimental factors (1) alloy composition, (2) grain size, (3) thermomechanical processing, and (4) room temperature deformation plus final age were evaluated by tensile and stress rupture testing at 1200 F. Various levels of the four factors were assumed in order to construct the statistically-designed experiment, but the actual levels investigated were established in preliminary studies that preceded the statistical process development study.

  6. Thermal and Electrical Conductivity of Porous Metals made by Powder Metallurgy Methods

    Microsoft Academic Search

    P Grootenhuis; R W Powell; R P Tye

    1952-01-01

    Measurements are reported of the thermal conductivity and electrical resistivity over the range of 20° c to 200° c on several specimens of a sintered porous bronze material (89% Cu, 11% Sn). The constituent powder particles were substantially spherical in shape and the specimens studied covered particle diameters ranging from 0.00133 to 0.040 cm and had densities from 5.27 to

  7. Development of Rare-Earth Free Mn-Al Permanent Magnet Employing Powder Metallurgy Route

    NASA Astrophysics Data System (ADS)

    Singh, N.; Shyam, R.; Upadhyay, N. K.; Dhar, A.

    2015-02-01

    Most widely used high-performance permanent magnets are currently based on intermetallics of rare-earths in combination with Fe and Co. Rare-earth elements required for these magnets are getting expensive by the day. Consequently, there is a thrust worldwide to develop economical rare-earth free permanent magnets. It is acknowledged that the phase in Mn-Al alloys possesses magnetic properties without the presence of ferromagnetic elements such as Fe, Co, and Ni. In the present study, we report the synthesis of magnetic phase of Mn54Al46 alloy synthesized using mechanical alloying followed by solutionizing and annealing to obtain the desired magnetic phase. It is well known that Al dissolves partially in Mn matrix hence supersaturated solid solution of Mn54Al46 alloy powder was obtained by mechanical alloying using a planetary high-energy ball mill. For this purpose elemental Mn and Al powders were ball-milled in Argon atmosphere at 400 rpm using stainless steel bowl with ball to powder ratio of 15:1. These mechanically alloyed Mn54Al46 powders were then consolidated using spark plasma sintering at 550°C for 20 min. followed by solution treatment at 1050°C for 5 hrs and then water quenched to retain high temperature phase. Subsequently, the Mn54Al46 samples were annealed in the temperature range 450°C-650°C to obtain the magnetic phase. These samples were characterized by XRD and SEM and the magnetic properties were measured using a vibrating sample magnetometer (VSM). It was observed that the magnetization and coercivity of MnAl magnets exhibited strong dependence on annealing temperature and annealing time.

  8. Niobium-titanium superconductors produced by powder metallurgy having artificial flux pinning centers

    SciTech Connect

    Jablonski, P.D.; Larbalestier, D.C.

    1993-07-13

    A superconducting wire structure is described comprising: a matrix comprising body centered cubic niobium-titanium alloy with a second phase of discrete metal inclusions compatible with niobium-titanium providing artificial pinning centers distributed therein, at least some second phase inclusions having sizes in the range of 1 to 10 nm, the second phase comprising between 5 to 50% by volume of the total matrix and second phase, wherein the second phase is selected from the group consisting of niobium, vanadium, tantalum, hafnium, zirconium, titanium, tungsten, molybdenum, chromium, copper, silver, gold and alloys thereof, and wherein the wire structure is formed by deforming and drawing a billet comprising a mixture of a first phase powder comprising the body centered cubic niobium-titanium alloy with a second phase powder of the metal compatible with niobium-titanium, the second phase comprising from 5% to 50% by volume of the mixture, the mixture pressed and sintered to provide a bond between the powder particles without significant diffusion of the second phase into the first phase or significant diffusion of the first phase into the second phase.

  9. The Effect of Forging Variables on the Supersolvus Heat-Treatment Response of Powder-Metallurgy Nickel-Base Superalloys

    NASA Astrophysics Data System (ADS)

    Semiatin, S. L.; Shank, J. M.; Shiveley, A. R.; Saurber, W. M.; Gaussa, E. F.; Pilchak, A. L.

    2014-12-01

    The effect of subsolvus forging temperature and strain rate on the grain size developed during final supersolvus heat treatment (SSHT) of two powder-metallurgy, gamma-gamma prime superalloys, IN-100 and LSHR, was established. For this purpose, isothermal, hot compression tests were performed at temperatures ranging from 1144 K (871 °C) and 22 K (22 °C) below the respective gamma-prime solvus temperatures ( T ?') and strain rates between 0.0003 and 10 s-1. Deformed samples were then heat treated 20 K (20 °C) above the solvus for 1 h with selected additional samples exposed for shorter and longer times. For both alloys, the grain size developed during SSHT was in the range of 15 to 30 ?m, except for those processing conditions consisting of pre-deformation at the highest temperature, i.e., T ?'—22 K ( T ?'—22 °C), and strain rates in the range of ~0.001 to 0.1 s-1. In these latter instances, the heat-treated grain size was approx. four times as large. The observations were interpreted in terms of the mechanisms of deformation during hot working and their effect on the driving forces for grain-boundary migration which controls the evolution of the gamma-grain size.

  10. The Effect of Forging Variables on the Supersolvus Heat-Treatment Response of Powder-Metallurgy Nickel-Base Superalloys

    NASA Astrophysics Data System (ADS)

    Semiatin, S. L.; Shank, J. M.; Shiveley, A. R.; Saurber, W. M.; Gaussa, E. F.; Pilchak, A. L.

    2014-09-01

    The effect of subsolvus forging temperature and strain rate on the grain size developed during final supersolvus heat treatment (SSHT) of two powder-metallurgy, gamma-gamma prime superalloys, IN-100 and LSHR, was established. For this purpose, isothermal, hot compression tests were performed at temperatures ranging from 1144 K (871 °C) and 22 K (22 °C) below the respective gamma-prime solvus temperatures (T ?') and strain rates between 0.0003 and 10 s-1. Deformed samples were then heat treated 20 K (20 °C) above the solvus for 1 h with selected additional samples exposed for shorter and longer times. For both alloys, the grain size developed during SSHT was in the range of 15 to 30 ?m, except for those processing conditions consisting of pre-deformation at the highest temperature, i.e., T ?'—22 K (T ?'—22 °C), and strain rates in the range of ~0.001 to 0.1 s-1. In these latter instances, the heat-treated grain size was approx. four times as large. The observations were interpreted in terms of the mechanisms of deformation during hot working and their effect on the driving forces for grain-boundary migration which controls the evolution of the gamma-grain size.

  11. Nanostructured interpenetrating phase composites by non-equilibrium compaction of in situ synthesized powders

    Microsoft Academic Search

    O. I. Lomovsky; D. V. Dudina; M. A. Korchagin; V. I. Mali; Y.-S. Kwon; J.-S. Kim

    2005-01-01

    We suggest using two-stage processing of metal-ceramic interpenetrating phase composites (IPCs) including preparation of composite powder precursors by reaction in a metal matrix and subsequent compaction of as-synthesized nanostructured powders. The appropriate choice of compaction technique allows obtaining dense nanostructured bulk IPCs. Bulk nanostructured TiB2-Cu IPCs were fabricated by spark plasma sintering (SPS) and shock wave compaction of powder precursors.

  12. Effect of reduced cobalt contents on hot isostatically pressed powder metallurgy U-700 alloys

    NASA Technical Reports Server (NTRS)

    Harf, F. H.

    1982-01-01

    The effect of reducing the cobalt content of prealloyed powders of UDIMET 700 (U-700) alloys to 12.7, 8.6, 4.3, and 0% was examined. The powders were hot isostatically pressed into billets, which were given heat treatments appropriate for turbine disks, namely partial solutioning at temperatures below the gamma prime solvus and four step aging treatments. Chemical analyses, metallographic examinations, and X-ray diffraction measurements were performed on the materials. Minor effects on gamma prime content and on room temperature and 650 C tensile properties were observed. Creep rupture lives at 650 C reached a maximum at the 8.4% concentration, while at 760 C a maximum in life was reached at the 4.3% cobalt level. Minimum creep rates increased with decreasing cobalt content at both test temperatures. Extended exposures at 760 and 815 C resulted in decreased tensile strengths and rupture lives for all alloys. Evidence of sigma phase formation was also found.

  13. Chloride-induced stress corrosion cracking of powder metallurgy duplex stainless steels

    SciTech Connect

    Laitinen, A.; Haenninen, H. [Helsinki Univ. of Technology, Espoo (Finland). Lab. of Engineering Materials

    1996-04-01

    The chloride-induced stress corrosion cracking (SCC) resistance of nitrogen-alloyed, powder metallurgically (P/M) produced and hot isostatically pressed (HIP) duplex stainless steels (DSS) was investigated and compared to the SCC resistance of two commercial wrought (forged) DSS. Constant-strain (deflection) SCC tests with four-point, loaded-bend specimens were performed in aerated 50 wt% calcium chloride solution at 100 C with pH = 6.5 to 7.0. The pitting corrosion resistance index value (PREN) was not a suitable parameter to predict SCC resistance of the investigated DSS. Instead of pitting corrosion, selective corrosion of the austenite or ferrite phases seemed to determine the SCC resistance of each material. Selective corrosion was not the primary cause for failure, but it assisted the initiation and growth of stress corrosion cracks. Selective corrosion was noticed in all of the investigated DSS. The corroding phase, austenite or ferrite, was dependent on the material. High copper content in the specific material slightly lowered the stress limit at which stress corrosion cracks started to grow in the used test solution. The SCC resistance of P/M-HIP DSS was as good as the SCC resistance of forged DSS. The banded microstructure of forged DSS led to a directional selective corrosion attack. The corrosion grooves were ideal sites for initiation of SCC. Because of this phenomenon, the homogeneous microstructure of P/M-HIP DSS showed clear advantages over the banded microstructure of forged DSS.

  14. The properties of aluminum alloys containing nickel, produced using powder metallurgy method

    NASA Astrophysics Data System (ADS)

    Naeem, Haider T.; Mohammad, Kahtan S.; Jamaludin Shamsul, B.; Ahmad, Khairel R.; Hussein, Wan M. H.

    2015-05-01

    In this paper, the effects of nickel on the microstructure and mechanical properties of experimental an Al-Zn-Mg-Cu PM alloys under the impacts of the retrogression and re-aging treatment was investigated. Green compacts pressed at 370 MPa were then sintered at temperature 650°C in argon atmosphere for two hours. The sintered samples subjected to the homogenizing condition at 470°C for 1.5 hours then aging at 120°C for 24 hours and retrogressed at 180°C for 30 minutes, and then re-aged at 120°C for 24 hours. Characterization's results indicate that the microstructures of an Al-Zn-Mg-Cu-Ni PM alloys presented an intermetallics compound in the aluminum's matrix, identified as the AlNi and Al3Ni2 phases besides the MgZn and Mg2Zn11 phases which produced of the precipitation hardening during heat treatment. These compounds with precipitates provided strengthening of dispersion that led to improved Vickers's hardness and dinsifications properties of the alloys.

  15. Investigation of Die Stress Profiles during Powder Compaction using Instrumented Die

    SciTech Connect

    Hong, Sung-tae; Hovanski, Yuri; Lavender, Curt A.; Weil, K. Scott

    2008-06-01

    The radial stress profile in a cylindrical die during compaction of titanium (Ti) powder was investigated by experiments. The concept of an instrumented die was extended to design an enhanced instrumented die. Custom-made strain gage pins were used to measure the radial stress during powder compaction. The test fixture was designed to simulate double-action pressing. The measured die stress profile for Ti powder was compared with that for a commercially available iron (Fe) powder. The stress history shows that an appreciable residual stress remains in the die in the radial direction after the axial compaction stress is removed from the powder. Furthermore, the radial stress profile in the die, while under maximum axial compaction stress, is more uniform across the height of the Fe compact than that of the Ti compact. In addition, the residual stress profile in the die in the radial direction reduces symmetrically in both directions beyond the height of the compact for both powders. Finally, the Ti powder shows a significantly higher frictional coefficient at the maximum axial compaction stress, and consequently a higher maximum axial ejection stress than the Fe powder.

  16. Finite Element Modeling on the Compaction of Copper Powder Under Different Conditions

    NASA Astrophysics Data System (ADS)

    An, Xizhong; Zhang, Yilei; Zhang, Yuxi; Yang, Shuo

    2015-05-01

    Single-action die compaction of copper powders with initial loose natural packing and vibrated random dense packing structures was carried out numerically by finite element method and physically for validation. Furthermore, the compaction under various cyclic loadings was modeled to identify its effects on the compact properties. The results were analyzed and compared between compacts formed at different initial packing structures and different forming conditions, which indicate that at the same pressure, single-action die compaction on the dense uniform initial packing can produce compacts with high relative density, uniform density and stress distributions, which implies the necessity to improve initial packing density and uniformity in forming high performance compacts. Meanwhile, by using cyclic loading on such dense initial packing structures, compacts with higher packing density and more uniform density and stress distributions can be created. The numerical and physical results are comparable and in good agreement with the proposed double logarithmic equation.

  17. Characterization by X-ray tomography of granulated alumina powder during in situ die compaction

    SciTech Connect

    Cottrino, Sandrine; Jorand, Yves, E-mail: yves.jorand@insa-lyon.fr; Maire, Eric; Adrien, Jérôme

    2013-07-15

    Compaction process, the aim of which being to obtain green bodies with low porosity and small size, is often used before sintering treatment. Prior to die filling, the ceramic powder is generally granulated to improve flowability. However during compaction, density heterogeneity and critical size defects may appear due to intergranule and granule-die wall frictions. In this work, the influence of granule formulation on the compact morphology has been studied. To do so, a compaction setup was installed inside an X-ray tomography equipment so that the evolution of the compact morphology could be analysed during the whole compaction process. We have demonstrated that high humidity rate and the addition of binder in the granule formulation increase density heterogeneity and generate larger defects. - Highlights: • An original compaction set up was installed inside an X-Ray tomography equipment. • The compaction process of granulated ceramic powder is imaged. • The compact green microstructure is quantified and related to the compaction stages. • The most detrimental defects of dry-pressed parts are caused by hollow granules. • Formulations without binder allow a reduction of the number of large defects.

  18. Towards an improved understanding of strength and anisotropy of cold compacted powder

    NASA Astrophysics Data System (ADS)

    Wang, Wenhai

    The strength of powder compacts after cold compaction is known to be anisotropic, which comes from the directionality of microstructure resulting from initial particle morphology and/or from particle deformation during compaction. Current work focuses on multi-scale numerical analysis of powder compaction with emphasis on the role of interparticle cohesion on post-compaction mechanical properties. At macroscopic level, we applied phenomenological model to describe the mechanical behavior of powder, in which the material is considered to be continuum medium. A user subroutine (VUMAT) was successfully developed for ABAQUS/Explicit analysis, in which one of the popular phenomenological models for powder compaction---Drucker Prager/Cap model---is implemented. By studying of pharmaceutical powder die compaction and subsequent diametrical compression test via finite element analysis, the capabilities and limitations of current constitutive models are evaluated on predicting such as density, stress and tool force evolution, as well as the strength and fracture tendency. Our results illustrate that current model has good predictive capability of powder densification (e.g. density evolution) but can not predict post-compaction strength well. The following studies focus on evaluating the physics and mechanics occurring at particle level. The compaction of granular media was explored by using MPFEM approach. In the new model, individual particles discretized with a finite element mesh allow for a full description of contact mechanics and local and global particle kinematics. The introduction of a layer of degrading material on the surface of each particle provides the means of introducing variable cohesion and its effect on the final strength of compacts. The simulations show that the unloading creates tensile stresses at the root of the contact necks, which may cause partial or full separation of contact interface when the cohesion developed during loading is not strong enough. These results, which are in agreement with recent strength anisotropy data for cold compaction, bring a new perspective on understanding the interparticle behavior and the origin of the strength and failure of cold compacts.

  19. Application of powder metallurgy to an advanced-temperature nickel-base alloy, NASA-TRW 6-A

    NASA Technical Reports Server (NTRS)

    Freche, J. C.; Ashbrook, R. L.; Waters, W. J.

    1971-01-01

    Bar stock of the NASA-TRW 6-A alloy was made by prealloyed powder techniques and its properties evaluated over a range of temperatures. Room temperature ultimate tensile strength was 1894 MN/sq m (274 500 psi). The as-extruded powder product showed substantial improvements in strength over the cast alloy up to 649 C (1200 F) and superplasticity at 1093 C (2000 F). Both conventional and autoclave heat treatments were applied to the extruded powder product. The conventional heat treatment was effective in increasing rupture life at 649 and 704 C (1200 and 1300 F); the autoclave heat treatment, at 760 and 816 C (1400 and 1500 F).

  20. On the Applicability of Analytical Models to Predict Hugoniot of Nano-Sized Powder Compacts

    NASA Astrophysics Data System (ADS)

    Dai, Chengda; Eakins, Daniel; Thadhani, Naresh

    2007-12-01

    We examine the applicability of two analytical models proposed respectively by McQueen et al and Wu-Jing, which are representative of isochoric and isobaric approaches for predicting the Hugoniot of nano-sized powder compacts obtained from experimental measurements. Model calculations show increasing deviation of the predicted Hugoniot from available experimental data with increasing porosity. Experimental measurements for nano-Fe powder pre-pressed to ˜35% and ˜45% solid density reveal that the Hugoniot cannot be well described by either model. The principal cause for the ineffectiveness is possibly due to the lack of incorporating the difference in internal energy between the powder compact and the solid. Both models may be improved to predict Hugoniot of nanoparticle compacts by considering the contribution of specific surface energy to specific internal energy of nanoparticles and the size effect of nanoparticles on lattice vibrations related to Grüneisen parameter.

  1. Finite element model of iron powder compaction at above room temperature

    NASA Astrophysics Data System (ADS)

    Rahman, M. M.; Ariffin, A. K.

    2015-05-01

    This paper presents the finite element modelling of iron powder compaction process at above ambient temperature. The deformation behaviour of powder mass at elevated temperature was assumed to be rate independent thermo-elastoplastic material where the material constitutive laws were derived based on a continuum mechanics approach by considering a large displacement based finite element formulation. The temperature dependent material parameters were established through experimentation. Two constitutive relations namely Mohr-Coulomb and Elliptical Cap yield models were used to represent the deformation behaviour of the powder mass during the compaction process. These yield models were tested, however an Elliptical Cap model was shown to be the most appropriate to represent the compaction process. The staggered-incremental-iterative solution strategy was established to solve the non-linearity in the systems of equations. Some numerical simulation results were validated through experimentation, where a good agreement was observed.

  2. Nanostructured bulk MnBi magnets fabricated by hot compaction of cryomilled powders

    NASA Astrophysics Data System (ADS)

    Rama Rao, N. V.; Gabay, A. M.; Li, W. F.; Hadjipanayis, G. C.

    2013-07-01

    Cryomilling was employed for Mn50+xBi50-x (x = 0,5) alloys to synthesize nanocrystalline powders with particle size of 400-500 nm without much increase of the unwanted secondary Bi phase. At room temperature, the cryomilled powders showed large coercivity (Hc) values of 18.5 kOe and 20.7 kOe for Mn50Bi50 and Mn55Bi45, respectively. Cryomilled powders were hot compacted to form a bulk nanostructured MnBi magnet. The Mn50Bi50 hot compacted magnet exhibits Hc of 12.9 kOe with remanence value of 26 emu g-1 at room temperature. The microstructure of hot compacted magnet illustrates uniform grains with an average size of 40 nm. Furthermore, the magnet shows a large positive temperature coefficient of Hc which reaches a value of more than 30 kOe above 450 K.

  3. Processing and Characterization of Cu-Al-Ni Shape Memory Alloy Strips Prepared from Prealloyed Powder by Hot Densification Rolling of Powder Preforms

    Microsoft Academic Search

    S. K. Vajpai; R. K. Dube; S. Sangal

    2011-01-01

    The present work deals with the preparation of near-full density Cu-Al-Ni shape memory alloy (SMA) strips from argon-atomized prealloyed powder via a powder metallurgy (PM) route comprising cold die compaction to prepare powder preforms, sintering, and hot densification rolling of unsheathed sintered powder preforms under protective atmosphere at 1273 K (1000 °C). It has been shown that argon-atomized spherical Cu-Al-Ni

  4. Phase composition, microstructure, and mechanical properties of porous Ti-Nb-Zr alloys prepared by a two-step foaming powder metallurgy method.

    PubMed

    Rao, X; Chu, C L; Zheng, Y Y

    2014-06-01

    Porous Ti-Nb-Zr alloys with different porosities from 6.06 to 62.8% are prepared by a two-step foaming powder metallurgy method using TiH2, Nb, and Zr powders together with 0 to 50wt% of NH4HCO3. The effects of the amounts of Nb and Zr as well as the sintering temperature (1473 to 1673K) on their phase composition, porosity, morphology, and mechanical characteristics are investigated. By controlling the porosity, Nb and Zr concentrations as well as the sintering temperature, porous Ti-Nb-Zr alloys with different mechanical properties can be obtained, for example, the hardness between 290 and 63HV, the compressive strength between 1530.5 and 73.4MPa, and the elastic modulus between 10.8 and 1.2GPa. The mechanical properties of the sintered porous Ti-Nb-Zr alloys can be tailored to match different requirements for the human bones and are thus potentially useful in the hard tissue implants. PMID:24556322

  5. Mechanical properties of partially dense alumina produced from powder compacts

    Microsoft Academic Search

    David C. C. Lam; Fred F. Lange; Anthony G. Evans

    1994-01-01

    The elastic modulus (E), the critical strain energy release rate (G[sub c]), and the flexural strength ([sigma]) have been determined for two partially dense alumina bodies produced from the same powder but with different initial densities. The mechanical properties were measured for specimens fabricated at four different relative densities. The measured elastic modulus, critical strain energy release rate, and a

  6. Investigation into the compactability of metal powders during rolling

    Microsoft Academic Search

    V. P. Katashinskii; G. A. Vinogradov

    1965-01-01

    finishing stand of the IM- 1 of the Institute. The powder was rolled in a vertical direction. A single-point dynamometer was installed inside the roll, and is shown diagrammatically in Fig. 1. Plug 2 of KhVG steel is mounted in the roll (sliding fit), fixed in position by setscrew 3, and turned together with the roll. Thereupon the plug was

  7. Two methods for characterizing the compaction and ejection behavior of metal powders in a die 

    E-print Network

    Sajdak, Richard James

    1969-01-01

    &M University Directed by: Professor J. H. Caddess Pressure transfer characteristics of a number of copper and iron powders at different levels of lubrication have been studied. The results are reported as a dimensionless plot of transmi. tted- applied load... Strain Indicator, and 60, 000 Pound Baldwin Universal Testing Machine 17 Typical Calibration Curve of the Strain Gages . . 19 Dimensionless Compaction Curve of Electrolytic Iron Powder Showing the Effect of Lubricant Addition 22 Dimensionless...

  8. Modelling and Simulation of Tensile Fracture in High Velocity Compacted Metal Powder

    NASA Astrophysics Data System (ADS)

    Jonsén, P.; Häggblad, H.-A.?.

    2007-05-01

    In cold uniaxial powder compaction, powder is formed into a desired shape with rigid tools and a die. After pressing, but before sintering, the compacted powder is called green body. A critical property in the metal powder pressing process is the mechanical properties of the green body. Beyond a green body free from defects, desired properties are high strength and uniform density. High velocity compaction (HVC) using a hydraulic operated hammer is a production method to form powder utilizing a shock wave. Pre-alloyed water atomised iron powder has been HVC-formed into circular discs with high densities. The diametral compression test also called the Brazilian disc test is an established method to measure tensile strength in low strength material like e.g. rock, concrete, polymers and ceramics. During the test a thin disc is compressed across the diameter to failure. The compression induces a tensile stress perpendicular to the compressed diameter. In this study the test have been used to study crack initiation and the tensile fracture process of HVC-formed metal powder discs with a relative density of 99%. A fictitious crack model controlled by a stress versus crack-width relationship is utilized to model green body cracking. Tensile strength is used as a failure condition and limits the stress in the fracture interface. The softening rate of the model is obtained from the corresponding rate of the dissipated energy. The deformation of the powder material is modelled with an elastic-plastic Cap model. The characteristics of the tensile fracture development of the central crack in a diametrically loaded specimen is numerically studied with a three dimensional finite element simulation. Results from the finite element simulation of the diametral compression test shows that it is possible to simulate fracturing of HVC-formed powder. Results from the simulation agree reasonably with experiments.

  9. The powder flow and compact mechanical properties of two recently developed matrix-forming polymers.

    PubMed

    Hancock, B C; Carlson, G T; Ladipo, D D; Langdon, B A; Mullarney, M P

    2001-09-01

    The powder flow and compact mechanical properties of two recently developed matrix-forming polymers were determined. The polymers are cross-linked high-amylose starch (Contramid) and poly(acrylic acid) (Carbopol EX507), and their properties were compared with those of two established matrix-forming polymers, hydroxypropyl methylcellulose (Methocel K100LV) and hydroxypropyl cellulose (Klucel EXF). The particle morphology, size distribution and true density of the four materials were quite different and they exhibited measurable performance differences with respect to powder flow, compact ductility, compact elasticity and compact tensile strength. Recommendations for formulating solid dosage forms with each of these excipients were made, based on a consideration of their physical properties and their anticipated processing performance. PMID:11578101

  10. Cooling of Er(3+) with Tm(3+) for accurate temperature sensing using yttrium silicate compact powders.

    PubMed

    Rakov, Nikifor; Maciel, Glauco S

    2014-11-14

    Er(3+) doped nanocrystalline powders are extensively used for thermometry based on luminescence spectral analysis. The luminescence from Er(3+) is produced by a nonlinear (two-photon) absorption process which may generate strong internal heat by activation of nonradiative relaxation channels. If the heat dissipation is not efficient, as is the case for compact powders, there will be inaccurate readings of the temperature. Our proposed solution is to cool down Er(3+) by transferring part of its accumulated energy to another rare-earth element in the lattice. Here, we show our results for Er(3+)-Tm(3+) co-doped yttrium silicate powders prepared by combustion synthesis. PMID:25232991

  11. Consolidation processing parameters and alternative processing methods for powder metallurgy Al-Cu-Mg-X-X alloys

    NASA Technical Reports Server (NTRS)

    Sankaran, K. K.

    1987-01-01

    The effects of varying the vacuum degassing parameters on the microstructure and properties of Al-4Cu-1Mg-X-X (X-X = 1.5Li-0.2Zr or 1.5Fe-0.75Ce) alloys processed from either prealloyed (PA) or mechanically alloyed (M) powder, and consolidated by either using sealed aluminum containers or containerless vacuum hot pressing were studied. The consolidated billets were hot extruded to evaluate microstructure and properties. The MA Li-containing alloy did not include Zr, and the MA Fe- and Ce-containing alloy was made from both elemental and partially prealloyed powder. The alloys were vacuum degassed both above and below the solution heat treatment temperature. While vacuum degassing lowered the hydrogen content of these alloys, the range over which the vacuum degassing parameters were varied was not large enough to cause significant changes in degassing efficiency, and the observed variations in the mechanical properties of the heat treated alloys were attributed to varying contributions to strengthening by the sub-structure and the dispersoids. Mechanical alloying increased the strength over that of alloys of similar composition made from PA powder. The inferior properties in the transverse orientation, especially in the Li-containing alloys, suggested deficiencies in degassing. Among all of the alloys processed for this study, the Fe- and Ce-containing alloys made from MA powder possessed better combinations of strength and toughness.

  12. Effects of thermocapillary forces during welding of 316L-type wrought, cast and powder metallurgy austenitic stainless steels

    Microsoft Academic Search

    S. Sgobba; T. Daniellou

    2003-01-01

    The Large Hadron Collider (LHC) is now under construction at the European Organisation for Nuclear Research (CERN). This 27km long accelerator requires 1248 superconducting dipole magnets operating at 1.9K. The cold mass of the dipole magnets is closed by a shrinking cylinder and two end covers at both extremities of the cylinder. The end covers are welded, cast or powder

  13. Investigation of Conventional- and Induction-Sintered Iron and Iron-Based Powder Metal Compacts

    NASA Astrophysics Data System (ADS)

    Çavdar, U?ur; Atik, Enver

    2014-06-01

    Induction sintering was developed as an alternative method to conventional sintering to sinter iron-based powder metal (PM) compacts. Several compositions of compact such as pure iron, 3 wt.% copper mixed iron, or 3 wt.% bronze mixed iron were sintered by using induction sintering machines with 12 kW power and 30 kHz frequency. The mechanical properties, microstructural properties, densities, and microhardness values were investigated for both processes. Iron-based PM compacts sintered at 1120°C by induction in 8.33 min (500 s) were found to be similar to those sintered conventionally in 30 min. The results were compared with the experimental studies.

  14. Investigation of compaction and sintering behavior of SiC powder after ultra-fine treatment.

    PubMed

    Guo, Xing-Zhong; Yang, Hui

    2004-08-01

    Silicon carbide ceramics were prepared with SiC powder treated by the fluidized bed opposed jet mill as raw materials, and the effects of the ultra-fine treatment mechanism on the compaction and sintering behavior of SiC ceramics were investigated. The results showed that the compacts had higher density and microstructure homogeneity when the sintering temperature of the compact was decreased; and that the surface microstructure, densification and mechanical properties of the sintered body could be ameliorated obviously. PMID:15236481

  15. Compaction of Ceramic Microspheres, Spherical Molybdenum Powder and Other Materials to 3 GPa

    SciTech Connect

    Carlson, S R; Bonner, B P; Ryerson, F J; Hart, M M

    2006-01-27

    Pressure-volume relationships were measured at room temperature for eight granular materials and one specimen of epoxy foam. The granular materials included hollow ceramic microspheres, spherical molybdenum powder, Ottawa sand, aluminum, copper, titanium and silicon carbide powders and glassy carbon spheres. Measurements were made to 0.9 GPa in a liquid medium press for all of the granular materials and to 3 GPa in a solid medium press for the ceramic microspheres and molybdenum powder. A single specimen of epoxy foam was compressed to 30 MPa in the liquid medium press. Bulk moduli were calculated as a function of pressure for the ceramic microspheres, the molybdenum powder and three other granular materials. The energy expended in compacting the granular materials was determined by numerically integrating pressure-volume curves. More energy was expended per unit volume in compacting the molybdenum powder to 1 GPa than for the other materials, but compaction of the ceramic microspheres required more energy per gram due to their very low initial density. The merge pressure, the pressure at which all porosity is removed, was estimated for each material by plotting porosity against pressure on a semi-log plot. The pressure-volume curves were then extrapolated to the predicted merge pressures and numerically integrated to estimate the energy required to reach full density for each material. The results suggest that the glassy carbon spheres and the ceramic microspheres would require more energy than the other materials to attain full density.

  16. Measuring internal temperature profiles in microwave-heated ceramic powder compacts

    Microsoft Academic Search

    J. H. Booske; R. F. Cooper; K. R. Binger

    1998-01-01

    Summary form only given. Experimental evidence has been reported by various groups indicating that microwave heating can accelerate the sintering of ceramic powder compacts in comparison with conventional furnace heating. At least one physical phenomenon-a nonlinear ponderomotive force-has been identified as a candidate explanation for these observations. However, the subject still remains controversial, including challenges for reliable measurement of internal

  17. Shock compression response of nanoiron powder compact Chengda Dai,a

    E-print Network

    Liu, J. Ping

    Shock compression response of nanoiron powder compact Chengda Dai,a Daniel Eakins, and Naresh Received 20 November 2006; accepted 17 January 2007; published online 15 February 2007 The shock on shock stress and wave velocity measurements using piezoelectric stress gauges. The obtained data show

  18. Simulation of polymer removal from a powder injection molding compact by thermal debinding

    Microsoft Academic Search

    Y. C. Lam; S. C. M. Yu; K. C. Tam; Ying Shengjie

    2000-01-01

    Powder injection molding (PIM) is an important net-shape manufacturing process. Thermal debinding is a common methodology for the final removal of residual polymer from a PIM compact prior to sintering. This process is an intricate combination of evaporation, liquid and gas migration, pyrolysis of polymer, and heat transfer in porous media. A better understanding of thermal debinding could lead to

  19. Manufacture of nickel base composite materials with dispersed glass particles by the powder metallurgy method. Part I

    Microsoft Academic Search

    B. L. Rudoi; M. Kh. Shorshorov; G. M. Matveev; B. A. Borok; R. P. Shchegoleva

    1974-01-01

    1.A technique has been developed for the manufacture of rods of nickel base composite materials containing crystallizing glass particles. Such rods are characterized by a uniform distribution of dispersed phase particles throughout the metal and have densities close to theoretical.2.A study was made of the specific load in the extrustion of sintered compacts as a function of the amount and

  20. A comparative study of roll compaction of free-flowing and cohesive pharmaceutical powders.

    PubMed

    Yu, Shen; Gururajan, Bindhu; Reynolds, Gavin; Roberts, Ron; Adams, Michael J; Wu, Chuan-Yu

    2012-05-30

    Roll compaction is widely adopted as a dry granulation method in the pharmaceutical industry. The roll compaction behaviour of feed powders is primarily governed by two parameters: the maximum pressure and the nip angle. Although the maximum pressure can be measured directly using pressure sensors fitted in the rolls, it is not a trivial task to determine the nip angle, which is a measure of the size of the compaction zone and hence the degree of compression. Thus a robust approach based upon the calculation of the pressure gradient, which can be obtained directly from experiments using an instrumented roll compactor, was developed. It has been shown that the resulting nip angles are comparable to those obtained using the methods reported in literature. Nevertheless, the proposed approach has distinctive advantages including (1) it is based on the intrinsic features of slip and no-slip interactions between the powder and roll surface and (2) it is not necessary to carry out wall friction measurements that involve plates that may not be representative of the roll compactor in terms of the surface topography and surface energy. The method was evaluated by investigating the effect of roll speed for two pharmaceutical excipients with distinctive material properties: microcrystalline cellulose (MCC) and di-calcium phosphate dihydrate (DCPD). It was found that the maximum pressure and nip angle for DCPD, which is a cohesive powder, decrease sharply with increasing roll speed whereas they are essentially independent of roll speed for MCC, which is an easy flowing powder. The roll compaction behaviour of MCC-DCPD mixtures with various compositions was also investigated in order to evaluate the effect of flowability. It was found that the nip angle and maximum pressure generally increased with improved flowability of the feed powders. PMID:22402475

  1. Modelling of the mechanical behaviour of two pure PTFE powders during their compaction at room temperature

    NASA Astrophysics Data System (ADS)

    Frédy, Carole; Canto, Rodrigo B.; Schmitt, Nicolas; Roux, Stéphane; Billardon, René

    2013-06-01

    Since PolyTetraFluoroEthylene (PTFE) is not melt processible because of its very high melt viscosity, parts made of this material are generally manufactured by cold compaction of powder material followed by sintering of the green compact. The aim of this study is to identify 3-D constitutive equations suitable for the finite element analysis of PTFE powder compaction. To exhibit the influence of their geometrical aspect on their mechanical behaviour, two pure PTFE resins were tested, viz. a free flowing pelletized resin and a granular fine cut resin. To study the behaviour of these powders during their compaction along different loading paths, a novel triaxial device has been designed and installed on a six-actuator triaxial testing machine. The results obtained for hydrostatic loading were favourably compared with results obtained by isostatic pressing. Various complex loading paths were also investigated. Full 3D elasto-viscoplastic non-associated constitutive equations, viz. a non-linear Drucker-Prager/cap type model, could be identified.

  2. Tungsten and tungsten alloy powder metallurgy: Powder production and applications excluding lamps. (Latest citations from the US Patent bibliographic file with exemplary claims). Published Search

    SciTech Connect

    NONE

    1995-02-01

    The bibliography contains citations of selected patents concerning the preparation of metallic and ceramic powders of tungsten and tungsten alloys, including applications of these materials. The hydrogen reduction of tungsten compounds together with alloying element compounds produce forms with characteristics of high density, hardness, wear resistance, high melting points, and abrasiveness. Topics include production of cathodes, heaters, filament wires, electrical contacts, acoustic absorbers, high-density sheets and coatings, hard penetrators, and tungsten carbide and metallized ceramics. Tungsten halogen lamps are examined in a separate bibliography. (Contains a minimum of 115 citations and includes a subject term index and title list.)

  3. Tungsten and tungsten alloy powder metallurgy: Powder production and applications excluding lamps. (Latest citations from the US Patent database). Published Search

    SciTech Connect

    Not Available

    1993-05-01

    The bibliography contains citations of selected patents concerning the preparation of metallic and ceramic powders of tungsten and tungsten alloys, including applications of these materials. The hydrogen reduction of tungsten compounds together with alloying element compounds produce forms with characteristics of high density, hardness, wear resistance, high melting points, and abrasiveness. Topics include production of cathodes, heaters, filament wires, electrical contacts, acoustic absorbers, high-density sheets and coatings, hard penetrators, and tungsten carbide and metallized ceramics. Tungsten halogen lamps are examined in a separate bibliography. (Contains a minimum of 97 citations and includes a subject term index and title list.)

  4. Tungsten and tungsten alloy powder metallurgy: Powder production and applications excluding lamps. (Latest citations from the US Patent bibliographic file with exemplary claims). Published Search

    SciTech Connect

    NONE

    1995-12-01

    The bibliography contains citations of selected patents concerning the preparation of metallic and ceramic powders of tungsten and tungsten alloys, including applications of these materials. The hydrogen reduction of tungsten compounds together with alloying element compounds produce forms with characteristics of high density, hardness, wear resistance, high melting points, and abrasiveness. Topics include production of cathodes, heaters, filament wires, electrical contacts, acoustic absorbers, high-density sheets and coatings, hard penetrators, and tungsten carbide and metallized ceramics. Tungsten halogen lamps are examined in a separate bibliography.(Contains 50-250 citations and includes a subject term index and title list.) (Copyright NERAC, Inc. 1995)

  5. Tungsten and tungsten alloy powder metallurgy: Powder production and applications excluding lamps. (Latest citations from the US Patent bibliographic file with exemplary claims). Published Search

    SciTech Connect

    Not Available

    1994-04-01

    The bibliography contains citations of selected patents concerning the preparation of metallic and ceramic powders of tungsten and tungsten alloys, including applications of these materials. The hydrogen reduction of tungsten compounds together with alloying element compounds produce forms with characteristics of high density, hardness, wear resistance, high melting points, and abrasiveness. Topics include production of cathodes, heaters, filament wires, electrical contacts, acoustic absorbers, high-density sheets and coatings, hard penetrators, and tungsten carbide and metallized ceramics. (Contains a minimum of 109 citations and includes a subject term index and title list.)

  6. Tungsten and tungsten alloy powder metallurgy: Powder production and applications excluding lamps. (Latest citations from the US Patent bibliographic file with exemplary claims). Published Search

    SciTech Connect

    NONE

    1997-01-01

    The bibliography contains citations of selected patents concerning the preparation of metallic and ceramic powders of tungsten and tungsten alloys, including applications of these materials. The hydrogen reduction of tungsten compounds together with alloying element compounds produce forms with characteristics of high density, hardness, wear resistance, high melting points, and abrasiveness. Topics include production of cathodes, heaters, filament wires, electrical contacts, acoustic absorbers, high-density sheets and coatings, hard penetrators, and tungsten carbide and metallized ceramics. Tungsten halogen lamps are examined in a separate bibliography.(Contains 50-250 citations and includes a subject term index and title list.) (Copyright NERAC, Inc. 1995)

  7. Effects of C and Hf concentration on phase relations and microstructure of a wrought powder-metallurgy superalloy

    NASA Technical Reports Server (NTRS)

    Miner, R. V., Jr.

    1977-01-01

    NASA IIB-11, a candidate alloy for advanced temperature turbine engine disks, and four modifications with varying C and Hf concentrations were produced from prealloyed powders. Several notable effects of C and Hf concentration in the alloys were observed. Both the amount of the gamma-prime phase and its solvus temperature increased with decreasing C, but only the gamma-prime solvus was affected by Hf, increasing with increasing Hf. Hf also promoted a cellular gamma-prime precipitation. Hf was, however, about equally distributed between gamma-prime and gamma. Hf and C both affected the carbides formed. Increasing both promoted formation of an MC relative to that of an M6C.

  8. Oxidation behavior in reaction-bonded aluminum-silicon alloy/alumina powder compacts

    SciTech Connect

    Yokota, S.H.

    1992-12-01

    Goal of this research is to determine the feasibility of producing low-shrinkage mullite/alumina composites by applying the reaction-bonded alumina (RBAO) process to an aluminum-silicon alloy/alumina system. Mirostructural and compositional changes during heat treatment were studied by removing samples from the furnace at different steps in the heating schedule and then using optical and scanning electron microscopy, EDS and XRD to characterize the powder compacts. Results suggest that the oxidation behavior of the alloy compact is different from the model proposed for the pure Al/alumina system.

  9. Processing of dielectric oxynitride perovskites for powders, ceramics, compacts and thin films.

    PubMed

    Masubuchi, Y; Sun, S-K; Kikkawa, S

    2015-06-21

    Oxynitride perovskites, having oxide and nitride anions together in a compound, are a new class of dielectric material. The shaping process in either bulk ceramics or thin films is an essential factor for investigating and utilizing the dielectric properties of these materials. In this perspective, recent studies on the shaping of dielectric oxynitride perovskites are reviewed with a consideration of the powder preparation and thermal stability for sintering, several sintering methods, ultra-high pressure compaction, and thin-film formation. PMID:25727932

  10. Self-propagating high-temperature (combustion) synthesis (SHS) of powder-compacted materials

    Microsoft Academic Search

    H. C. Yi; J. J. Moore

    1990-01-01

    Self-propagating high-temperature synthesis (SHS) of powder compacts is a novel processing technique currently being developed as a route for the production of engineering ceramics and other advanced materials. The process, which is also referred to as combustion synthesis, provides energy- and cost-saving advantages over the more conventional processing routes for these materials. At the same time, the rapid heating and

  11. A study on laser sintering of Fe-Cu powder compacts

    Microsoft Academic Search

    Ping Shen; Jiandong Hu; Zuoxing Guo; Qingfeng Guan

    1999-01-01

    The sintering of Fe-Cu powder compacts by laser beams was studied to determine densification and microstructural development.\\u000a The influence of processing variables such as Cu content, laser output power, sintering time, and green density on the densification\\u000a and Brinell hardness (HB) were analyzed, and several temperature curves measured during laser sintering (LS) were also discussed\\u000a in this article. After LS,

  12. Simulation of polymer removal from a powder injection molding compact by thermal debinding

    Microsoft Academic Search

    Y. C. Lam; S. C. M. Yu; K. C. Tam; Ying Shengjie

    2000-01-01

    Powder injection molding (PIM) is an important net-shape manufacturing process. Thermal debinding is a common methodology\\u000a for the final removal of residual polymer from a PIM compact prior to sintering. This process is an intricate combination\\u000a of evaporation, liquid and gas migration, pyrolysis of polymer, and heat transfer in porous media. A better understanding\\u000a of thermal debinding could lead to

  13. Correlations between the in vitro and in vivo bioactivity of the Ti/HA composites fabricated by a powder metallurgy method.

    PubMed

    Ning, Congqin; Zhou, Yu

    2008-11-01

    Ti/HA composites were successfully prepared by a powder metallurgy method and the effect of phase composition on the in vitro and in vivo bioactivity of the Ti/HA composites was investigated in the present study. The correlations between the in vitro and in vivo biological behaviors were highlighted. The results showed that the in vitro and in vivo bioactivity of the Ti/HA composites was dependent on their phase composition. The in vitro bioactivity of the Ti/HA composites was evaluated in simulated body fluid with ion concentrations similar to those of human plasma. After immersion in the simulated body fluid for a certain time, apatite precipitations formed on the surface of the composites with an initial titanium content of 50 and 70 wt.%, and no apatite was found on the surface of the composite with 30% titanium. Ti(2)O was responsible for the apatite formation on the surfaces of the composites. For in vivo analysis, Ti/HA cylinders were implanted in the metaphases of the rabbit femur. At the early stage of implantation, the new bone formed on the surface of the composite with 30% titanium was much less than that on the surfaces of the composites with 50% and 70% titanium. All the Ti/HA composites formed a chemical bone-bonding interface with the host bone by 6 months after implantation. The Ti/HA composites formed the bone-bonding interface with the surrounding bone through an apatite layer. The results in the present study suggested that the in vivo results agreed well with the in vitro results. PMID:18502711

  14. Weak hydrogen bonding interactions influence slip system activity and compaction behavior of pharmaceutical powders.

    PubMed

    Khomane, Kailas S; Bansal, Arvind K

    2013-12-01

    Markedly different mechanical behavior of powders of polymorphs, cocrystals, hydrate/anhydrate pairs, or structurally similar molecules has been attributed to the presence of active slip planes system in their crystal structures. Presence of slip planes in the crystal lattice allows easier slip under the applied compaction pressure. This allows greater plastic deformation of the powder and results into increased interparticulate bonding area and greater tensile strength of the compacts. Thus, based on this crystallographic feature, tableting performance of the active pharmaceutical ingredients can be predicted. Recently, we encountered a case where larger numbers of C?H···O type interactions across the proposed slip planes hinder the slip and thus resist plastic deformation of the powder under the applied compaction pressure. Hence, attention must be given to these types of interactions while identifying slip planes by visualization method. Generally, slip planes are visualized as flat layers often strengthened by a two-dimensional hydrogen-bonding network within the layers or planes. No hydrogen bonding should exist between these layers to consider them as slip planes. Moreover, one should also check the presence of C?H···O type interactions across these planes. Mercury software provides an option for visualization of these weak hydrogen bonding interactions. Hence, caution must be exercised while selecting appropriate solid form based on this crystallographic feature. PMID:24136007

  15. Deformation mechanisms and strain storage during forging of powder-metallurgy nickel-base turbine disk alloy

    NASA Astrophysics Data System (ADS)

    Tu, Wen J.

    Nickel-based superalloys account for 50% of the total weight of high temperature gas turbine engines. Increasing the lifespan and temperature capabilities of superalloy turbine blades and disks can significantly increase the efficiency and cost of the engines. The properties of superalloy disk materials, including strength and fatigue resistance, are sensitive to the grain structure at the end of a series of thermomechanical processing. To date, there have been few fundamental studies on deformation mechanisms and microstructural evolution under conditions relevant to forging of superalloy disk materials. In this study, high temperature compression testing combined with high resolution Electron Backscatter Diffraction (EBSD) analysis has been used to analyze microstructural-scale straining processes that occur during high temperature deformation of a powder-consolidated nickel-based superalloy, Rene 88DT. Orientation imaging has been employed to study grain-level straining and strain storage at temperatures, strains, and strain rates of interest. Two distinct deformation mechanisms were observed using these techniques. At strain rates below 0.001/s, superplastic deformation dominates at temperature between 1241K (968°C) and 1323K (1050°C). At strain rates above 0.001/s, a combination of superplastic and power-law creep deformation mechanisms is evident. At the highest strain rates, power-law creep deformation dominates. Using experimental evidence along with previous studies, constitutive models of deformation mechanisms and microstructure evolution during high temperature compression are proposed. The proposed models predict the boundaries of deformation mechanisms along with the material response to imposed deformation conditions such as superplasticity-enhanced grain growth and dynamic recrystallization.

  16. Parameter dependent thermal conductivity model for titanium and graphite powder mixture compact

    SciTech Connect

    Azad, G.M.S.; Cui, T.; Huque, Z. [Prairie View A and M Univ., Prairie View, TX (United States). Dept. of Mechanical Engineering

    1996-12-31

    Self-Propagating High-Temperature Synthesis (SHS) is an energy-efficient combustion method of producing refractory, ceramic, and composite materials from their constituent powders. To accurately model the SHS process it is important to understand the physical and chemical mechanisms involved in the reaction process along with the effects of various microstructural and physical parameters controlling the process. Physical parameters include the initial temperature of the green compact, thermal conductivity of the compact, density, particle size and mixture ratio of the constituents. Of these parameters, effective thermal conductivity is directly dependent on the initial density, mixing ratio and the particle size of the constituents. Here, the effects of initial density, composition mixture ratio, and particle size on thermal conductivity of titanium and graphite powder mixture compact has been experimentally investigated and a thermal conductivity model has been developed. Thermal conductivity values have been measured for compact densities ranging from 45% to 775 of maximum theoretical density and for Ti/C mixture ratio by weight ranging from 0.7 to 1.3. The model predicts that, for an increase in density, thermal conductivity increases but it decreases with an increase of Ti/C mixture ratio. The experimental results also show the dependence trend of thermal conductivity on particle size of the constituents.

  17. Processing and Characterization of Cu-Al-Ni Shape Memory Alloy Strips Prepared from Prealloyed Powder by Hot Densification Rolling of Powder Preforms

    Microsoft Academic Search

    S. K. Vajpai; R. K. Dube; S. Sangal

    The present work deals with the preparation of near-full density Cu-Al-Ni shape memory alloy (SMA) strips from argon-atomized\\u000a prealloyed powder via a powder metallurgy (PM) route comprising cold die compaction to prepare powder preforms, sintering, and hot densification\\u000a rolling of unsheathed sintered powder preforms under protective atmosphere at 1273 K (1000 °C). It has been shown that argon-atomized\\u000a spherical Cu-Al-Ni SMA powder

  18. Understanding deformation mechanisms during powder compaction using principal component analysis of compression data.

    PubMed

    Roopwani, Rahul; Buckner, Ira S

    2011-10-14

    Principal component analysis (PCA) was applied to pharmaceutical powder compaction. A solid fraction parameter (SF(c/d)) and a mechanical work parameter (W(c/d)) representing irreversible compression behavior were determined as functions of applied load. Multivariate analysis of the compression data was carried out using PCA. The first principal component (PC1) showed loadings for the solid fraction and work values that agreed with changes in the relative significance of plastic deformation to consolidation at different pressures. The PC1 scores showed the same rank order as the relative plasticity ranking derived from the literature for common pharmaceutical materials. The utility of PC1 in understanding deformation was extended to binary mixtures using a subset of the original materials. Combinations of brittle and plastic materials were characterized using the PCA method. The relationships between PC1 scores and the weight fractions of the mixtures were typically linear showing ideal mixing in their deformation behaviors. The mixture consisting of two plastic materials was the only combination to show a consistent positive deviation from ideality. The application of PCA to solid fraction and mechanical work data appears to be an effective means of predicting deformation behavior during compaction of simple powder mixtures. PMID:21624449

  19. Thermal analysis of self-propagating high-temperature reactions in titanium, boron, and aluminum powder compacts

    Microsoft Academic Search

    L. H. Chiu; D. C. Nagle; L. A. Bonney

    1999-01-01

    This article focuses on the characterization of self-propagating high-temperature synthesis (SHS) reactions that occur in\\u000a powder compacts containing titanium, boron, and aluminum. Interest in this powder system is based on the critical need to\\u000a develop new joining techniques for bonding ceramics to metals. The exothermic reactions of particular interest in this study\\u000a include those that generate TiB2, TiB, Ti3Al, and

  20. The influence of morphology on the low- and high-strain-rate compaction response of CeO2 powders

    NASA Astrophysics Data System (ADS)

    Fredenburg, D. A.; Koller, D. D.; Coe, Joshua D.; Kiyanda, C. B.

    2014-03-01

    The low- and high-strain-rate compaction response of three distinct morphology CeO2 powders was measured experimentally. At low-strain-rates, the compression path was found to vary with initial particle morphology as a result of differences in initial packing structure and particle rearrangement at low stresses. However, similar compression responses were observed at higher stresses under low-strain-rate loading. Dynamic experiments were performed at impact velocities between 0.15 and 0.78 km/s, and resulted in compaction stresses of 0.51-4.59 GPa in the powders. In contrast to the behavior observed at low stresses and low-strain-rates, dynamic loading resulted in a similar compaction response for all morphology powders. The dynamic results were treated with a Hayes equation of state augmented with a P-? compaction model, and good agreement between experimental and theoretical results was achieved. From the observed similarities in compressibility for the three morphology powders at elevated stresses at both low- and high-strain-rates, a relationship is proposed linking the measured strength properties at low-strain-rates to those controlling the compaction response under dynamic loading.

  1. Plutonium Metallurgy

    SciTech Connect

    Freibert, Franz J. [Los Alamos National Laboratory

    2012-08-09

    Due to its nuclear properties, Pu will remain a material of global interest well into the future. Processing, Structure, Properties and Performance remains a good framework for discussion of Pu materials science Self-irradiation and aging effects continue to be central in discussions of Pu metallurgy Pu in its elemental form is extremely unstable, but alloying helps to stabilize Pu; but, questions remain as to how and why this stabilization occurs. Which is true Pu-Ga binary phase diagram: US or Russian? Metallurgical issues such as solute coring, phase instability, crystallographic texture, etc. result in challenges to casting, processing, and properties modeling and experiments. For Ga alloyed FCC stabilized Pu, temperature and pressure remain as variables impacting phase stability.

  2. Development and characterization of Powder Metallurgy (PM) 2XXX series Al alloy products and Metal Matrix Composite (MMC) 2XXX Al/SiC materials for high temperature aircraft structural applications

    NASA Technical Reports Server (NTRS)

    Chellman, D. J.; Gurganus, T. B.; Walker, J. A.

    1992-01-01

    The results of a series of material studies performed by the Lockheed Aeronautical Systems Company over the time period from 1980 to 1991 are discussed. The technical objective of these evaluations was to develop and characterize advanced aluminum alloy materials with temperature capabilities extending to 350 F. An overview is given of the first five alloy development efforts under this contract. Prior work conducted during the first five modifications of the alloy development program are listed. Recent developments based on the addition of high Zr levels to an optimum Al-Cu-Mg alloy composition by powder metallurgy processing are discussed. Both reinforced and SiC or B4C ceramic reinforced alloys were explored to achieve specific target goals for high temperature aluminum alloy applications.

  3. A study on laser sintering of Fe-Cu powder compacts

    SciTech Connect

    Shen, P.; Hu, J.; Guo, Z.; Guan, Q. [Jilin Univ. of Technology, Changchun (China)

    1999-08-01

    The sintering of Fe-Cu powder compacts by laser beams was studied to determine densification and microstructural development. The influence of processing variables such as Cu content, laser output power, sintering time, and green density on the densification and Brinell hardness (HB) were analyzed, and several temperature curves measured during laser sintering (LS) were also discussed in this article. After LS, the samples exhibited considerable shrinkage, which was very different from the effects of conventional sintering (CS). The main reasons for shrinkage are the laser`s very fast heating rates, short sintering times, and relatively high sintering temperatures. As a consequence, insufficient time is available for Fe particles to diffuse in the solid state to form a rigid skeleton. After formation, the liquid penetrates quickly along boundaries and separates the Fe particles, leading to rapid collapse and particle rearrangement, which finally results in considerable shrinkage. An increased Cu content, laser output power, and sintering time can promote shrinkage and hardness, but compact slumping occurs when the laser power is too high.

  4. Effects of nickel on the sintering behavior of Fe-Ni compacts made from composite and elemental powders

    SciTech Connect

    Hwang, K.S. [National Taiwan Univ., Taipei (Taiwan, Province of China). Inst. of Materials Science and Engineering; Shiau, M.Y. [Team Young Advanced Ceramics Co. Ltd., Taoyuan (Taiwan, Province of China)

    1996-04-01

    Injection-molded Fe-Ni parts made from composite and elemental powders were prepared, and the effect of nickel on the sintering of iron compacts was investigated. Dilatometry analyses showed that the alpha-gamma phase transformation temperature of the Fe-Ni compact changed from a fixed 912 C for pure iron to a temperature range between 700 C and 912 C where two phases coexisted. The microstructure indicated that nickel impeded surface diffusion and slowed down the neck growth rate of iron powder in the early sintering stage. The dual phase and the small neck size at low temperatures suppressed the exaggerated grain growth, which usually occurs on carbonyl iron powders at 912 C. It was also observed that nickel impeded the grain growth of iron at high temperatures. Thus, by reducing the exaggerated grain growth during phase transformation, impeding the grain growth at high temperatures, and with high diffusion rates of iron in Ni-rich areas, enhanced densification was obtained for Fe-Ni systems, particularly for those systems made from composite powders. However, when coarse nickel powder was added, expansion was observed due to the presence of large pores around nickel powders. These pores were formed because of the particle rearrangement which was caused by the Kirkendall effect.

  5. Investigation of the potential for direct compaction of a fine ibuprofen powder dry-coated with magnesium stearate.

    PubMed

    Qu, Li; Zhou, Qi Tony; Gengenbach, Thomas; Denman, John A; Stewart, Peter J; Hapgood, Karen P; Gamlen, Michael; Morton, David A V

    2015-05-01

    Intensive dry powder coating (mechanofusion) with tablet lubricants has previously been shown to give substantial powder flow improvement. This study explores whether the mechanofusion of magnesium stearate (MgSt), on a fine drug powder can substantially improve flow, without preventing the powder from being directly compacted into tablets. A fine ibuprofen powder, which is both cohesive and possesses a low-melting point, was dry coated via mechanofusion with between 0.1% and 5% (w/w) MgSt. Traditional low-shear blending was also employed as a comparison. No significant difference in particle size or shape was measured following mechanofusion. For the low-shear blended powders, only marginal improvement in flowability was obtained. However, after mechanofusion, substantial improvements in the flow properties were demonstrated. Both XPS and ToF-SIMS demonstrated high degrees of a nano-scale coating coverage of MgSt on the particle surfaces from optimized mechanofusion. The study showed that robust tablets were produced from the selected mechanofused powders, at high-dose concentration and tablet tensile strength was further optimized via addition of a Polyvinylpyrrolidone (PVP) binder (10% w/w). The tablets with the mechanofused powder (with or without PVP) also exhibited significantly lower ejection stress than those made of the raw powder, demonstrating good lubrication. Surprisingly, the release rate of drug from the tablets made with the mechanofused powder was not retarded. This is the first study to demonstrate such a single-step dry coating of model drug with MgSt, with promising flow improvement, flow-aid and lubrication effects, tabletability and also non-inhibited dissolution rate. PMID:24738790

  6. Combustion synthesis of Ti 3AlC 2 from Ti\\/Al\\/C\\/TiC powder compacts

    Microsoft Academic Search

    C. L. Yeh; Y. G. Shen

    2008-01-01

    Preparation of the ternary carbide Ti3AlC2 was conducted by combustion synthesis in the mode of self-propagating high-temperature synthesis (SHS) from both the elemental powder compacts of Ti:Al:C=3:1:2 and the TiC-containing samples compressed from the powder mixtures of Ti\\/Al\\/C\\/TiC with TiC content ranging from 4.35 to 26.3mol%. The effect of TiC addition was studied on combustion characteristics and the degree of

  7. A Structural Investigation into the Compaction Behavior of Pharmaceutical Composites Using Powder X-ray Diffraction and Total Scattering Analysis

    Microsoft Academic Search

    Michael D. Moore; Alison M. Steinbach; Ira S. Buckner; Peter L. D. Wildfong

    2009-01-01

    Purpose  To use advanced powder X-ray diffraction (PXRD) to characterize the structure of anhydrous theophylline following compaction,\\u000a alone, and as part of a binary mixture with either ?-lactose monohydrate or microcrystalline cellulose.\\u000a \\u000a \\u000a \\u000a \\u000a Materials and Methods  Compacts formed from (1) pure theophylline and (2) each type of binary mixture were analyzed intact using PXRD. A novel mathematical\\u000a technique was used to accurately separate

  8. Investigation of the effects of pressure on the compaction and subsequent sintering of nanosize powders. Final report

    SciTech Connect

    Gonzalez, E.J.; Piermarini, G.J.; Hockey, B.; Malghan, S.G. [National Inst. of Standards and Technology, Gaithersburg, MD (United States). Ceramics Div.

    1996-02-26

    With current technology and available raw materials, one knows that it is very difficult, if not impossible, to produce a monolithic ceramic material with an average grain size of less than 100 nm. The grains of ceramic materials cannot be refined by cold working as is typically done in metals. Hence, the starting ceramic powder must be of a smaller or similar particle size as the desired grain size for the final product. The availability of nanosize (<100 nm) ceramic powders, however, is limited. In many cases, the powders consist of polymorphic mixtures, precursors, or amorphous phases of the desired material. Phase transformation during sintering is difficult to control, and when it does occur it usually is accompanied by significant microstructural changes and grain growth. An example of such a powder is Al{sub 2}O{sub 3}. To the best of the authors` knowledge, high purity nanosize {alpha}-Al{sub 2}O{sub 3} powder is unavailable commercially. However, a variety of nanosize transitional forms of Al{sub 2}O{sub 3}, including the {gamma} and {delta} polymorphs, are commercially available in large quantities as mixtures. Results on the compaction and sintering of nanosize {gamma}-Al{sub 2}O{sub 3} powder are reported here.

  9. Low temperature synthesis of anorthite based glass-ceramics via sintering and crystallization of glass-powder compacts

    Microsoft Academic Search

    V. M. F. Marques; D. U. Tulyaganov; S. Agathopoulos; V. Kh. Gataullin; G. P. Kothiyal; J. M. F. Ferreira

    2006-01-01

    Anorthite based glass-ceramics were synthesized. The investigated glass compositions are located close to the anorthite-rich corner of the fluorapatite–anorthite–diopside ternary system. Glass powder compacts with mean particle size of 2 and 10?m were prepared. Sintering behaviour, crystallization and the properties of glass-ceramics were investigated between 800 and 950°C. In the case of specimens made from the finer particles, complete densification

  10. Investigation on the effect of lubrication and forming parameters to the green compact generated from iron powder through warm forming route

    Microsoft Academic Search

    M. M. Rahman; S. S. M. Nor; H. Y. Rahman

    2011-01-01

    In order to generate green compacts of iron ASC 100.29 powder at above ambient temperature and below its recrystallization temperature, a warm compaction rig is designed and fabricated which can be operated at various temperature and load. The aim of this paper is to present the outcomes of an investigation on the effect of lubrication and forming parameters, i.e., load

  11. Formation and magnetic properties of the L10 phase in bulk, powder and hot compacted Mn-Ga alloys

    NASA Astrophysics Data System (ADS)

    Mix, T.; Müller, K.-H.; Schultz, L.; Woodcock, T. G.

    2015-10-01

    The formation and stability of the L10 phase in Mn-Ga binary alloys with compositions in the range 50-75 at% Mn (in steps of 5 at%) has been studied. Of these, single-phase L10 structure was successfully produced in the 55, 60 and 65 at% Mn alloys by annealing the high temperature phases, which had been retained to room temperature following arc melting. Further annealing and thermal analysis were used to determine the phase transformation temperatures in the alloys and the results were used to guide further processing. The saturation magnetisation, Ms, and the anisotropy field, Ha, were determined in applied fields up to 14 T. For Mn55Ga45, ?0Ms=0.807 T and ?0Ha=4.4 T were observed. Mechanically milled Mn55Ga45 powder had coercivity of ?0Hc=0.393 T, which was a twentyfold increase compared to the bulk material but the magnetisation was reduced (cf. powder: ?0M5 T=0.576 T, bulk: ?0M5 T=0.780 T). Annealing the powder at 400 °C led to recovery of the magnetisation but reduced the coercivity, which was still 10 times as high as the bulk value. A degree of texture of 0.45 was achieved by magnetic alignment of the powder particles, leading to a remanence of 0.526 T. Furthermore, isotropic hot compacts of powders were produced with packing density from 83% to 99%, in which the improved coercivity of the powders was partially retained.

  12. Fabrication of fully dense nanostructured MnBi magnet by hot compaction of cryo-milled powders

    NASA Astrophysics Data System (ADS)

    Hadjipanayis, George; Neelam, Venkata; Gabay, Alex; Li, Wang

    2013-03-01

    Recently, rare-earth-free permanent magnets (REFPMs) have attracted much attention globally owing to rare-earth metal crisis and high cost. Among the REFPMs, MnBi is a potential candidate due to its unusual large magnetocrystalline anisotropy (K ~ 107 erg/cc) and positive temperature of coefficient of coercivity. In this work, we report for the first time a novel processing method that combines the cryo-milling with hot compaction to produce fully dense bulk nanostructured MnBi magnet. The effect of cryo-milling on particle size, phase formation, and magnetic properties of MnBi has been studied in detail. Also, the microstructural and magnetic properties of bulk nanostructured MnBi magnet were investigated. Adoption of cryo-milling results in nanocrystalline powders with particle size of 400-500 nm. Large coercivity (Hc) values of 18.5 kOe, and 12.9 kOe were obtained in cryo-milled powders and hot compacted magnet respectively. The MnBi magnet shows a large positive temperature coefficient of Hc and the Hc reaches a value of more than 30 kOe above 450 K. Recently, rare-earth-free permanent magnets (REFPMs) have attracted much attention globally owing to rare-earth metal crisis and high cost. Among the REFPMs, MnBi is a potential candidate due to its unusual large magnetocrystalline anisotropy (K ~ 107 erg/cc) and positive temperature of coefficient of coercivity. In this work, we report for the first time a novel processing method that combines the cryo-milling with hot compaction to produce fully dense bulk nanostructured MnBi magnet. The effect of cryo-milling on particle size, phase formation, and magnetic properties of MnBi has been studied in detail. Also, the microstructural and magnetic properties of bulk nanostructured MnBi magnet were investigated. Adoption of cryo-milling results in nanocrystalline powders with particle size of 400-500 nm. Large coercivity (Hc) values of 18.5 kOe, and 12.9 kOe were obtained in cryo-milled powders and hot compacted magnet respectively. The MnBi magnet shows a large positive temperature coefficient of Hc and the Hc reaches a value of more than 30 kOe above 450 K. The work was supported by Siemens.

  13. Developments in Die Pressing Strategies for Low-Cost Titanium Powders

    SciTech Connect

    Hovanski, Yuri; Weil, K. Scott; Lavender, Curt A.

    2009-05-01

    Recent developments in the production of low-cost titanium powders have rejuvenated interest in manufacturing titanium powder metallurgy components by direct press and sinter techniques. However excessive friction typically observed during titanium powder pressing operations leads to numerous problems ranging from non-homogeneous green densities of the compacted powder to excessive part ejection forces and reduced die life due to wear and galling. An instrumented double-acting die press was developed to both investigate the mechanics of titanium powder pressing (particularly for the new low-cost powder morphologies) and to screen potential lubricants that could reduce frictional effects. As will be discussed, the instrument was used to determine friction coefficients and to evaluate a number of candidate lubricants. These results were then used to optimize the lubricant system to reduce die-wall stresses and improve part density uniformity.

  14. High strength-high conductivity Cu--Fe composites produced by powder compaction/mechanical reduction

    DOEpatents

    Verhoeven, John D. (Ames, IA); Spitzig, William A. (Ames, IA); Gibson, Edwin D. (Ames, IA); Anderson, Iver E. (Ames, IA)

    1991-08-27

    A particulate mixture of Cu and Fe is compacted and mechanically reduced to form an "in-situ" Cu-Fe composite having high strength and high conductivity. Compaction and mechanical reduction of the particulate mixture are carried out at a temperature and time at temperature selected to avoid dissolution of Fe into the Cu matrix particulates to a harmful extent that substantially degrades the conductivity of the Cu-Fe composite.

  15. High strength-high conductivity Cu-Fe composites produced by powder compaction/mechanical reduction

    DOEpatents

    Verhoeven, J.D.; Spitzig, W.A.; Gibson, E.D.; Anderson, I.E.

    1991-08-27

    A particulate mixture of Cu and Fe is compacted and mechanically reduced to form an ''in-situ'' Cu-Fe composite having high strength and high conductivity. Compaction and mechanical reduction of the particulate mixture are carried out at a temperature and time at temperature selected to avoid dissolution of Fe into the Cu matrix particulates to a harmful extent that substantially degrades the conductivity of the Cu-Fe composite. 5 figures.

  16. Tungsten and tungsten-alloy powder metallurgy: Powder production and applications-excluding lamps. November 1971-July 1989 (Citations from the US Patent data base). Report for November 1971-July 1989

    SciTech Connect

    Not Available

    1989-10-01

    This bibliography contains citations of selected patents concerning the preparation of metallic and ceramic powders of tungsten and tungsten alloys including various applications of these materials. The hydrogen reduction of tungsten compounds together with alloying-element compounds produce forms with characteristics of high density, hardness, wear resistance, high melting points, and abrasiveness. Topics include production of various cathodes, heaters, filament wires, electrical contacts, acoustic absorbers, high-density sheets and coatings, hard penetrators, and tungsten carbide and metallized ceramics. Tungsten halogen lamps are examined in a separate bibliography. (Contains 60 citations fully indexed and including a title list.)

  17. Interaction of Tournemire argillite (Aveyron, France) with hyperalkaline fluids: Batch experiments performed with powdered and/or compact materials

    NASA Astrophysics Data System (ADS)

    Devol-Brown, I.; Tinseau, E.; Bartier, D.; Mifsud, A.; Stammose, D.

    Argillaceous rocks and concrete matrix are considered as potential host rocks and engineered barrier, respectively for radioactive waste repositories. The concrete matrix could react with the groundwater of the geological site, inducing a drastic change in its chemical composition and pH. Consequently, the physico-chemical properties of the rock in contact with this hyperalkaline fluid may be modified. Therefore, an experimental programme has been developed for examining the physico-chemical changes of claystone in contact with alkaline fluids: batch experiments undertaken as a preliminary step followed by diffusion and percolation experiments in order to describe and to assess the physico-chemical phenomena observed under repository conditions. The first series of batch experiments are carried out in order to study the degradation of the Tournemire argillite properties caused by a fluid resulting from a contact with fresh concrete, considered as the most aggressive in relation to its hyper alkaline pH (?13). Thus, the influence of several parameters is tested, such as liquid/rock ratio (L/R 3-30 g/g), contact time (1-3 months), temperature (25-70 °C) and oxygen concentration. To compare the effect of the concrete maturity on the argillite physico-chemical damage, the second series of batch experiments are performed with a fluid resulting from a contact with moderately degraded concrete. Experiments are carried out on powdered and compact samples in order to identify structural and geochemical modifications. Before and after contact with simplified concrete fluids, powdered solids were mainly characterised by XRD (with measurements of specific surface area and SEM observations for a selection of samples) whereas compact materials were only observed by SEM. The chemical composition of the recovered solutions was also determined for their major anions and cations with their carbon content and pH values. Interpretations are based on solid analyses and aqueous chemistry. The comparison of results obtained with powdered and compact solids is only feasible for short time experiments. Aqueous chemistry and solid analyses indicate the dissolution of pyrite, dolomite and organic carbon with the precipitation of calcite. Precipitations of zeolites and K-feldspars occur sometimes and are only evidenced by SEM analyses. Nevertheless, silicates dissolution or precipitation is unclear through XRD analyses. Experimental conditions influence widely the intensity/nature of processes and prevent the transposition of data obtained in given conditions to other ones.

  18. Metastable structures in metallurgy

    Microsoft Academic Search

    David Turnbull

    1981-01-01

    Metastable structures or, more accurately, configurationally frozen metastable structures are no novelty in metallurgy. Indeed,\\u000a much of the traditional practice of metallurgy has centered on the formation, characterization, understanding and control\\u000a of structures which are either compositionally, topologically and\\/or morphologically metastable. However, in the past two\\u000a to three decades we have seen a great upsurge in the production and study

  19. Impact Initiation of Pressed Al-Based Intermetallic-Forming Powder Mixture Compacts

    Microsoft Academic Search

    S. W. Du; N. N. Thadhani

    2009-01-01

    Aluminum-based intermetallic forming powder mixtures (Ni-Al, Ta-Al, Nb-Al, Mo-Al and W-Al) were uniaxially pressed into 90% dense pellets, to study the impact initiation of reactions. The pressed pellets were mounted in front of a projectile and impacted onto a steel anvil using a 7.62 mm gas gun, under a 50 millitorr vacuum. Projectiles made of copper, aluminum or poly carbonate,

  20. Metallurgy and properties of plasma spray formed materials

    NASA Technical Reports Server (NTRS)

    Mckechnie, T. N.; Liaw, Y. K.; Zimmerman, F. R.; Poorman, R. M.

    1992-01-01

    Understanding the fundamental metallurgy of vacuum plasma spray formed materials is the key to enhancing and developing full material properties. Investigations have shown that the microstructure of plasma sprayed materials must evolve from a powder splat morphology to a recrystallized grain structure to assure high strength and ductility. A fully, or near fully, dense material that exhibits a powder splat morphology will perform as a brittle material compared to a recrystallized grain structure for the same amount of porosity. Metallurgy and material properties of nickel, iron, and copper base alloys will be presented and correlated to microstructure.

  1. Warm Compaction Forming of a Binder-Treated Fe-Base Material

    Microsoft Academic Search

    Tungwai Leo NGAI; Ying-huan KUANG; Yuan-yuan LI

    2007-01-01

    It is well known that increasing density is the best way to increase the performance of powder metallurgy (PM) parts. Conventional PM processing can produce iron-base parts with density less than 7.2 g\\/cm3. Their mechanical properties are substantially less than their full density counterpart. With minor modification on the conventional PM equipment, green compact density of 7.4 g\\/cm3 can be

  2. Neutron powder diffraction of small-volume samples at high pressure using compact opposed-anvil cells and focused beam

    NASA Astrophysics Data System (ADS)

    Okuchi, T.; Sasaki, S.; Ohno, Y.; Abe, J.; Arima, H.; Osakabe, T.; Hattori, T.; Sano-Furukawa, A.; Komatsu, K.; Kagi, H.; Utsumi, W.; Harjo, S.; Ito, T.; Aizawa, K.

    2012-07-01

    Neutron powder diffraction techniques of small-volume samples at high pressure using compact opposed-anvil cells were developed at J-PARC pulsed neutron source. For this purpose we apply a few types of super-hard materials as opposed anvils with culet diameters between 3 to 5 mm. Generated pressures with these anvils were up to 9 GPa for 2 to 4 mm3 and up to 14 GPa for 0.7 mm3 sample volumes, which not only depends on the anvil geometry and material but even more depends on the metallic gasket geometry and material. A representative anvil geometry with 4 mm in culet diameter, along with TiZr "null alloy" metallic gasket containing varying sample volumes, were then applied to time-of-flight neutron powder diffraction experiments, where methane hydrate of 4 mm3 volume and lead of 0.7 mm3 volume were separately measured and their signal-to-background ratios were evaluated. A neutron-focusing optics was used to concentrate the neutron beam into these small-volume samples to increase the intensity of diffraction. Although spurious diffraction peaks from the anvils were prominent, more than seven diffraction peaks are clearly observed from both of the samples. In spite of the smaller sample capacity than previous standard high-pressure apparatus for neutron, it is concluded that the opposed-anvil cells will become alternative apparatuses for neutron scattering at strong pulsed neutron sources where sufficient neutron intensity was granted.

  3. 1987 annual powder metallurgy conference proceedings

    SciTech Connect

    Not Available

    1987-01-01

    This book contains over 50 selections. Some of the titles are: High strength tungsten heavy alloys with molybdenum additions; Gravitational contributions to microstructural coarsening in liquid phase sintering; Large area sheet from P/M materials; Liquid phase sintering of carbides using a nickel-molybdenum alloy; and Influence of structures on fracture and fracture toughness of cemented tungsten carbides.

  4. Diffusion and Swelling Measurements in Pharmaceutical Powder Compacts Using Terahertz Pulsed Imaging

    E-print Network

    Yassin, Samy; Su, Ke; Lin, Hungyen; Gladden, Lynn F.; Zeitler, J. Axel

    2015-02-02

    of Eudragit, lac- tose, and HPMC using the compaction simulator. The dashed black line corresponds to the readings from the lower punch and the red line shows the forces acting on the upper punch. Yassin et al., JOURNAL OF PHARMACEUTICAL SCIENCES DOI 10... to wavelengths of 5.00 to 0.09 mm. High- resistivity silicon lenses and silicon probe optics focus the tera- hertz radiation to a diffraction-limited spot (200 :m diameter at a distance of 7 mm in front of the optics), where the sample is placed. A homemade...

  5. Finite-strain formulation and FE implementation of a constitutive model for powder compaction

    NASA Astrophysics Data System (ADS)

    Stupkiewicz, S.; Piccolroaz, A.; Bigoni, D.

    2015-01-01

    A finite-strain formulation is developed, implemented and tested for a constitutive model capable of describing the transition from granular to fully dense state during cold forming of ceramic powder. This constitutive model (as well as many others employed for geomaterials) embodies a number of features, such as pressure-sensitive yielding, complex hardening rules and elastoplastic coupling, posing considerable problems in a finite-strain formulation and numerical implementation. A number of strategies are proposed to overcome the related problems, in particular, a neo-Hookean type of modification to the elastic potential and the adoption of the second Piola-Kirchhoff stress referred to the intermediate configuration to describe yielding. An incremental scheme compatible with the formulation for elastoplastic coupling at finite strain is also developed, and the corresponding constitutive update problem is solved by applying a return mapping algorithm.

  6. Metallurgy Department Progress Report for

    E-print Network

    Risø-R-444 Metallurgy Department Progress Report for the Period l January to 31 December 1980 "Stiffness Based Fatigue Damage Characterization of Fibrous Composites" (page 53). #12;Risø-R-444 METALLURGY of the Metallurgy Departnent at Risø during 1980 are described. The work is presented in four chap- ters: General

  7. Power metallurgy tool electrodes for electrical discharge machining

    Microsoft Academic Search

    M. P. Samuel; P. K. Philip

    1997-01-01

    Electrodes in electrical discharge machining (EDM) can be compared with cutting tools in conventional machining. Tool performance is one of the important factors that determine the quality of the machined component. Due to the ease of manufacturing and control over the properties of electrodes, the powder metallurgy (P\\/M) technique has an advantage over other methods of electrode fabrication. P\\/M electrodes

  8. Extractive Metallurgy of Beryllium

    Microsoft Academic Search

    C. K. GUPTA; S. SAHA

    2002-01-01

    A comprehensive review of the extractive metallurgy of beryllium is presented. Due to the strategic importance and element of secrecy surrounding the metal, any open literature on beryllium is rather limited. However, this review has been made to cover all important aspects of beryllium extraction technology namely, resources of the metal; processing of ores; reduction of fluoride and oxide to

  9. Consolidation of aluminum 6061 powder by equal channel angular extrusion 

    E-print Network

    Pearson, John Montgomery

    1997-01-01

    Equal channel angular extrusion is a promising approach to obtaining full density in powder metallurgy applications. This method can impose large effective deformations through uniform shear strain. Aluminum alloy 6061 powder is used as a test...

  10. Improvement of the Dimensional Stability of Powder Injection Molded Compacts by Adding Swelling Inhibitor into the Debinding Solvent

    NASA Astrophysics Data System (ADS)

    Fan, Yang-Liang; Hwang, Kuen-Shyang; Su, Shao-Chin

    2008-02-01

    Defects are frequently found in powder injection molded (PIM) compacts during solvent debinding due to the swelling of the binders. This problem can be alleviated by adjusting the composition of the debinding solvent. In this study, 10 vol pct swelling inhibitors were added into heptane, and the in-situ amounts of swelling and sagging of the specimen in the solvent were recorded using a noncontacting laser dilatometer. The results show that the addition of ethanol, 2-propanol, 1-butanol, and 1-pentanol reduced the amounts of swelling by 31, 21, 17, and 11 pct, respectively. This was because the small molecule alcohols, which do not dissolve paraffin wax (PW) or stearic acid (SA) in the binder system, could diffuse easily into the specimen and increased the portion of the swelling inhibitor inside. The amount of the extracted PW and SA also decreased, but only by 8.3, 6.1, 4.3, and 2.4 pct, respectively. The solubility parameters of 1-bromopropane (n-PB) and ethyl acetate (EA) are between those of heptane and alcohols, and they also yielded a slight reduction in the amounts of swelling by 6 and 11 pct, respectively. These results suggest that to reduce defects caused by binder swelling during solvent debinding, alcohols with high solubility parameters can be added into heptane without sacrificing significantly on the debinding rate.

  11. Effects of TiC addition on formation of Ti 2SnC by self-propagating combustion of Ti–Sn–C–TiC powder compacts

    Microsoft Academic Search

    C. L. Yeh; C. W. Kuo

    2010-01-01

    Preparation of the ternary carbide Ti2SnC was conducted by combustion synthesis in the mode of self-propagating high-temperature synthesis (SHS) using both the elemental powder compacts and TiC-added samples with TiC contents from 2.6 to 17.6mol%. On account of the dilution effect of TiC on combustion, the reaction exothermicity was reduced by adopting TiC in the reactant mixture. As a result,

  12. Engineering in Process Metallurgy

    E-print Network

    New South Wales, University of

    calculation, recycle calculations, representation of materials balances, heat balance 2 Physical modelling Heat transfer in two dimensions and transient heat transfer finite system, Solidification of metal 10 Multiphase flow: gas-powder-liquid flow in moving bed 11 Powder flow in packed beds, pulverised

  13. An investigation on formation of Nb 2AlC by combustion synthesis of Nb 2O 5–Al–Al 4C 3 powder compacts

    Microsoft Academic Search

    C. L. Yeh; C. W. Kuo

    2010-01-01

    Preparation of layered ternary carbide Nb2AlC was conducted by combustion synthesis in the mode of self-propagating high-temperature synthesis (SHS) from Nb2O5–Al–Al4C3 powder compacts. Effects of the contents of Al and Al4C3 on the product composition and combustion behavior were studied by adopting two series of sample stoichiometries with Nb2O5:Al:Al4C3 varying from 3:9:1 to 3:13:1 (for supplying additional Al) and 3:9:1

  14. Metallurgy Beyond Iron

    NASA Astrophysics Data System (ADS)

    Gallino, Isabella; Busch, Ralf

    2009-08-01

    Metallurgy is one of the oldest sciences. Its history can be traced back to 6000 BCE with the discovery of Gold, and each new discovery - Copper, Silver, Lead, Tin, Iron and Mercury - marked the beginning of a new era of civilization. Currently there are 86 known metals, but until the end of the 17th century, only 12 of these were known. Steel (Fe-C alloy) was discovered in the 11th century BCE; however, it took until 1709 CE before we mastered the smelting of pig-iron by using coke instead of charcoal and started the industrial revolution. The metallurgy of nowadays is mainly about discovering better materials with superior properties to fulfil the increasing demand of the global market. Promising are the Glassy Metals or Bulk Metallic Glasses (BMGs) - discovered at first in the late 50s at the California Institute of Technology - which are several times stronger than the best industrial steels and 10-times springier. The unusual structure that lacks crystalline grains makes BMGs so promising. They have a liquid-like structure that means they melt at lower temperatures, can be moulded nearly as easily as plastics, and can be shaped into features just 10 nm across. The best BMG formers are based on Zr, Pd, Pt, Ca, Au and, recently discovered, also Fe. They have typically three to five components with large atomic size mismatch and a composition close to a deep eutectic. Packing in such liquids is very dense, with a low content of free volume, resulting in viscosities that are several orders of magnitude higher than in pure metal melts.

  15. Crystallography Materials Science and Metallurgy

    E-print Network

    Cambridge, University of

    Crystallography Materials Science and Metallurgy H. K. D. H. Bhadeshia The contents here: · Crystallography: Introduction · Crystallography: Advanced · Crystallography: Bravais lattices #12;2 #12;Contents 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 5.3 Crystallography of Diffraction

  16. Use of Cation Exchange Resins for Production of U{sub 3}O{sub 8} Suitable for the Al-U{sub 3}O{sub 8} Powder Metallurgy Process

    SciTech Connect

    Mosley, W.C.

    2001-09-17

    This report describes the production of U{sub 3}O{sub 8} powders from three types of cation exchange resins: Dowex 50W, a strong acid, sulfonate resin; AG MP-50, a macroporous form of sulfonate resin; and Bio-Rex 70, a weak acid, carboxylic resin.

  17. Steric stabilization of nonaqueous silicon slips. I - Control of particle agglomeration and packing. II - Pressure casting of powder compacts

    NASA Technical Reports Server (NTRS)

    Kerkar, Awdhoot V.; Henderson, Robert J. M.; Feke, Donald L.

    1990-01-01

    The application of steric stabilization to control particle agglomeration and packing of silicon powder in benzene and trichloroethylene is reported. The results provide useful guidelines for controlling unfavorable particle-particle interactions during nonaqueous processing of silicon-based ceramic materials. The application of steric stabilization to the control and improvement of green processing of nonaqueous silicon slips in pressure consolidation is also demonstrated.

  18. Dustiness behaviour of loose and compacted Bentonite and organoclay powders: What is the difference in exposure risk?

    Microsoft Academic Search

    Keld Alstrup Jensen; Ismo Kalevi Koponen; Per Axel Clausen; Thomas Schneider

    2009-01-01

    Single-drop and rotating drum dustiness testing was used to investigate the dustiness of loose and compacted montmorillonite\\u000a (Bentonite) and an organoclay (Nanofil®5), which had been modified from montmorillonite-rich Bentonite. The dustiness was analysed based on filter measurements as\\u000a well as particle size distributions, the particle generation rate, and the total number of generated particles. Particle monitoring\\u000a was completed using a

  19. Ris-M-2705 Metallurgy Department

    E-print Network

    O I *>K88oo>nu m1K Risø-M-2705 Metallurgy Department Publications 1987 '4^f\\feN Risø National Laboratory, DK-4000 Roskilde, Denmark April 1988 #12;wm Ris#-M-2705 Metallurgy Department Publications 1987) ofscientific and technical publications and lectures by the staff of the Metallurgy Department during 1987

  20. Sintering titanium powders

    SciTech Connect

    Gerdemann, Stephen J.; Alman, David E.

    2005-09-01

    Recently, there has been renewed interest in low-cost titanium. Near-net-shape powder metallurgy offers the potential of manufacturing titanium articles without costly and difficult forming and machining operations; hence, processing methods such as conventional press-and-sinter, powder forging and powder injection molding are of interest. The sintering behavior of a variety of commercial and experimental titanium powders was studied. Commercial powders were acquired that were produced different routes: (i) sponge fines from the primary titanium processing; (ii) via the hydride-dehydride process; and (iii) gas atomization. The influence of vacuum sintering time (0.5 to 32 hrs) and temperature (1200, 1275 or 1350°C) on the microstructure (porosity present) of cold pressed powders was studied. The results are discussed in terms of the difference in powder characteristics, with the aim of identify the characteristics required for full density via press-and-sinter processing. Near-net-shape tensile bars were consolidated via cold pressed and sintered. After sintering, a sub-set of the tensile bars was hot-isostatic pressed (HIPed). The microstructure and properties of the bars were compared in the sintered and HIPed conditions.

  1. University of Cambridge Department of Materials Science & Metallurgy

    E-print Network

    Cambridge, University of

    University of Cambridge Department of Materials Science & Metallurgy Modelling of Microstructural and Metallurgy, University of Cambridge, between May 2007 and August 2007. Except where acknowledgements

  2. Silicon solar cells: Physical metallurgy principles

    Microsoft Academic Search

    Michael G. Mauk

    2003-01-01

    This article reviews the physical metallurgy aspects of silicon solar cells. The production of silicon solar cells relies\\u000a on principles of thermochemical extractive metallurgy, phase equilibria, solidification, and kinetics. The issues related\\u000a to these processes and their impact on solar cell performance and cost are discussed.

  3. Extractive Metallurgy Today, Progress and Problems

    Microsoft Academic Search

    FATHI HABASHI

    1992-01-01

    In the past few years extractive metallurgy has been advancing gradually. There have beun probably few remarkable new ideas but there has been an important progress in the metallurgical literature. Numerous meetings devoted to various aspects of extractive metallurgy were held and,the proceedings of these meetings were published in the form of useful books readily available to the scientific community.

  4. Dual-Alloy Disks are Formed by Powder Metallurgy

    NASA Technical Reports Server (NTRS)

    Harf, F. H.; Miner, R. V.; Kortovich, C. S.; Marder, J. M.

    1982-01-01

    High-performance disks have widely varying properties from hub to rim. Dual property disk is fabricated using two nickel-base alloys, AF-115 for rim and Rene 95 for hub. Dual-alloy fabrication may find applications in automobiles, earth-moving equipment, and energy conversion systems as well as aircraft powerplants. There is potential for such applications as shafts, gears, and blades.

  5. Methods of increasing the erosion resistance of powder metallurgy steel

    SciTech Connect

    Kulu, P.A.

    1987-09-01

    The authors comparatively assess the effects of a variety of surface hardening methods--including carburizing, boriding, chromizing, and carbochromizing, as well as the flame, plasma arc, and detonation spraying of nickel and molybdenum coatings--on the wear, corrosion resistance, and pore structure of steel 45, and outline testing procedures used to arrive at their results.

  6. Heat treatment of powder metallurgy constructional steel (review)

    Microsoft Academic Search

    T. P. Moskvina; O. D. Sidorova

    1987-01-01

    An analysis of thermokinetic curves [6, 7] obtained in continuous cooling of austenite showed that in this case the porosity primarily influences thestability of the austenite. With an increase in 8 the length of the incubation period of the decomposition of austenite decreases and the area of its minimum stability shifts to higher temperatures. The shift in the curves of

  7. Freeform fabrication of functional aluminium prototypes using powder metallurgy

    Microsoft Academic Search

    T. B. Sercombe; G. B. Schaffer; P. Calvert

    1999-01-01

    Freeform fabrication methods allow the direct formation of parts built layer by layer, under the control of a CAD drawing. Most of these methods form parts in thermoplastic or thermoset polymers, but there would be many applications for freeform fabrication of fully functional metal or ceramic parts. We describe here the freeforming of sinterable aluminium alloys. In addition, the building

  8. Utilization of the electrohydraulic effect in powder metallurgy

    Microsoft Academic Search

    P. P. Malyushevskii; A. B. Tolstykh

    1979-01-01

    ti. t and ti. a -the total and active durations of the EDEVG impulse, respectively; tf, t d, ti. ! , and ff -the durations of the impulse front, impulse decay, loading impulse, and tail of the total displacement impulse of the EDEVG membrane, respectively; fir - the duration of the preceding train of elastic vibrations of the EDEYG. Experiments

  9. The imaging performance of compact Lu{sub 2}O{sub 3}:Eu powdered phosphor screens: Monte Carlo simulation for applications in mammography

    SciTech Connect

    Liaparinos, P. F.; Kandarakis, I. S. [Department of Medical Instruments Technology, Technological Educational Institute, 122 10 Athens (Greece)

    2009-06-15

    In medical mammographic imaging systems, one type of detector configuration, often referred to as indirect detectors, is based on a scintillator layer (phosphor screen) that converts the x-ray radiation into optical signal. The indirect detector performance may be optimized either by improving the structural parameters of the screen or by employing new phosphor materials with improved physical characteristics (e.g., x-ray absorption efficiency, intrinsic conversion efficiency, emitted light spectrum). Lu{sub 2}O{sub 3}:Eu is a relatively new phosphor material that exhibits improved scintillating properties indicating a promising material for mammographic applications. In this article, a custom validated Monte Carlo program was used in order to examine the performance of compact Lu{sub 2}O{sub 3}:Eu powdered phosphor screens under diagnostic mammography conditions (x-ray spectra: 28 kV Mo, 0.030 mm Mo and 32 kV W, 0.050 mm Rh). Lu{sub 2}O{sub 3}:Eu screens of coating weight in the range between 20 and 40 mg/cm{sup 2} were examined. The Monte Carlo code was based on a model using Mie-scattering theory for the description of light propagation within the phosphor. The overall performance of Lu{sub 2}O{sub 3}:Eu powdered phosphor screens was investigated in terms of the (i) quantum detection efficiency, (ii) luminescence efficiency, (iii) compatibility with optical sensors, (iv) modulation transfer function, (v) the Swank factor, and (vi) zero-frequency detective quantum efficiency. Results were compared to the traditional rare-earth Gd{sub 2}O{sub 2}S:Tb phosphor material. The increased packing density and therefore the light extinction properties of Lu{sub 2}O{sub 3}:Eu phosphor were found to improve the x-ray absorption (approximately up to 21% and 16% at 40 mg/cm{sup 2} for Mo and W x-ray spectra, respectively), the spatial resolution (approximately 2.6 and 2.4 cycles/mm at 40 mg/cm{sup 2} for Mo and W x-ray spectra, respectively), as well as the zero-frequency detective quantum efficiency (approximately up to 8% and 18% at 20 mg/cm{sup 2} for Mo and W x-ray spectra, respectively) of the screens in comparison to the Gd{sub 2}O{sub 2}S:Tb screens. Data obtained by the simulations indicate that certain optical properties of Lu{sub 2}O{sub 3}:Eu make this material a promising phosphor which, under appropriate conditions, could be considered for use in x-ray mammography imagers.

  10. Processing and Characterization of Cu-Al-Ni Shape Memory Alloy Strips Prepared from Prealloyed Powder by Hot Densification Rolling of Powder Preforms

    NASA Astrophysics Data System (ADS)

    Vajpai, S. K.; Dube, R. K.; Sangal, S.

    2011-10-01

    The present work deals with the preparation of near-full density Cu-Al-Ni shape memory alloy (SMA) strips from argon-atomized prealloyed powder via a powder metallurgy (PM) route comprising cold die compaction to prepare powder preforms, sintering, and hot densification rolling of unsheathed sintered powder preforms under protective atmosphere at 1273 K (1000 °C). It has been shown that argon-atomized spherical Cu-Al-Ni SMA powder consisted of very fine equiaxed grains and no appreciable grain growth occurred during sintering at 1273 K (1000 °C). It also has been shown that no appreciable densification occurred during sintering, and densification was primarily achieved by hot rolling. The densification behavior of the sintered powder preforms during hot rolling was discussed. The hot-rolled Cu-Al-Ni strips were heat-treated at 1223 K (950 °C) for 60 minutes and water quenched. The heat-treated strips consisted of equiaxed grains with average size approximately 90 ?m. The heat-treated Cu-Al-Ni SMA strips consisted of self-accommodated ?1' martensite primarily, and showed smooth ?1 Rightarrow ?1' transformation behavior coupled with a very low hysteresis (?25 K (25 °C)). The heat-treated strips exhibited an extremely good combination of mechanical properties with fracture strength of 530 MPa and 12.3 pct fracture strain. The mode of fracture in the finished strip was primarily void-coalescence-type ductile together with some brittle transgranular type. The shape memory tests showed almost 100 pct one-way shape recovery after 100 bending-unconstrained heating cycles at 4 pct applied prestrain, exhibiting good stability of Cu-Al-Ni strips under thermomechanical actuation cycling. The two-way shape memory strain was found approximately 0.45 pct after 15 training cycles at 4 pct training strain.

  11. Effects of Al and Al 4C 3 contents on combustion synthesis of Cr 2AlC from Cr 2O 3–Al–Al 4C 3 powder compacts

    Microsoft Academic Search

    C. L. Yeh; C. W. Kuo

    2011-01-01

    Preparation of the ternary carbide Cr2AlC was conducted by combustion synthesis in the mode of self-propagating high-temperature synthesis (SHS) from the Cr2O3–Al–Al4C3 powder compact. Effects of the contents of Al and Al4C3 on the product composition and combustion behavior were studied by formulating the reactant mixture with a stoichiometric proportion of Cr2O3:Al:Al4C3=3:5x:y, where x and y varied from 1.0 to

  12. Mound powder loader, Mod 1

    SciTech Connect

    Gress, A.V. Jr.

    1985-08-21

    At the investigation of Sandia Albuquerque, a semiautomatic powder loader was designed and fabricated for pyrotechnics devices. The basic functions of the system were to load a precise, measured amount of powder into a charge holder and to compact the mixture to a specified density. This report documents the history, rationale, design, and performance of the Mod 1 loader.

  13. Metal Powder ProcessingMetal Powder Processing ME 4210: Manufacturing Processes and Engineering

    E-print Network

    Colton, Jonathan S.

    shields Valve inserts, bushings, gears Electrical/electronic Heat treating Joining Lubrication Ag, Au, Mo is called greenp p g compact. (b) Typical tool and die set for compacting a spur gear. Source: Metal Powder

  14. Agglomeration of Food Powder and Applications

    Microsoft Academic Search

    K. Dhanalakshmi; S. Ghosal; S. Bhattacharya

    2011-01-01

    Agglomeration has many applications in food processing and major applications include easy flow table salt, dispersible milk powder and soup mix, instant chocolate mix, beverage powder, compacted cubes for nutritional-intervention program, health bars using expanded\\/puffed cereals, etc. The main purpose of agglomeration is to improve certain physical properties of food powders such as bulk density, flowability, dispersability, and stability. Agglomerated

  15. A Millennium of Metallurgy Recorded by Lake Sediments from

    E-print Network

    Wolfe, Alexander P.

    A Millennium of Metallurgy Recorded by Lake Sediments from Morococha, Peruvian Andes C O L I N, Pennsylvania 16802 To date, information concerning pre-Colonial metallurgy in South America has largely been the Morococha mining region in the central Peruvian Andes. The earliest evidence for metallurgy occurs ca. 1000

  16. Characterization and prediction of abrasive wear of powder composite materials

    Microsoft Academic Search

    R. Veinthal; P. Kulu; J. Pirso; H. Käerdi

    2009-01-01

    Composite materials produced by powder metallurgy provide a solution in many engineering applications where materials with high abrasion and erosion resistance are required. The actual wear behaviour of the material is associated with many external factors (particle size, velocity, angularity, etc.) and intrinsic material properties (hardness, toughness, Young modulus, etc.). Hardness and toughness properties of such tribomaterials are highly dependent

  17. Contributions a la caracterisation et a l'amelioration de l'usinabilite de pieces d'acier elaborees par metallurgie des poudres

    Microsoft Academic Search

    Patrick Boilard

    2009-01-01

    Even though powder metallurgy (P\\/M) is a near net shape process, a large number of parts still require one or more machining operations during the course of their elaboration and\\/or their finishing. The main objectives of the work presented in this thesis are centered on the elaboration of blends with enhanced machinability, as well as helping with the definition and

  18. Mystery Powders

    NSDL National Science Digital Library

    American Chemical Society

    2000-01-01

    In this activity on page 2 of the PDF, learners conduct chemical tests on certain powders used in cooking. After completing the tests, learners try to figure out the identity of a mystery powder. Learners record their observations on a chart. Note: you will need an adult helper for this activity.

  19. Characteristics of PMN-PT Powder Prepared by Partial Oxalate Process Route

    Microsoft Academic Search

    E. M. JAYASINGH; R. SOORAJ; K. PRABHAKARAN; C. DURGAPRASAD; S. C. SHARMA

    2009-01-01

    Powder compaction and sintering characteristics of the PMN-PT powder prepared by the partial oxalate route have been studied. The PMN-PT powder achieved 60% of theoretical density during compaction by pressing at 100 MPa. The powder compacts were sintered to > 99% TD at 1270°C for 2 hours. Microstructure of the sintered ceramic showed an average grain size of 6.1 ?

  20. The effect of high density electric pulses on sintered aluminum 201AB silicon carbide MMC PM compacts during plastic deformation

    NASA Astrophysics Data System (ADS)

    Dariavach, Nader Guseinovich

    The effect of high-density electrical pulses on mechanical and structural properties of sintered aluminum SiC metal-matrix composites, fabricated by standard powder-metallurgy compaction and sintering, was investigated. Three types of phenomena where investigated during transverse rupture testing of the samples: a consolidation effect (increasing of the transverse rupture strength (TRS)), an electroplastic effect (decreasing of the flow stresses), and an increasing of the stress intensity factor by electric pulse application. It was observed, that an increase in the TRS strength of sintered powder metallurgy (PM) aluminum and aluminum metal matrix composite (MMC) compacts is a result of the electric pulse consolidation effect due to non-uniform temperature distribution around the grain boundaries. Three analytical models of the thermal effect of electric pulses on aluminum samples where considered: total temperature change of the sample due to a one electric pulse, one-dimensional steady state model and transient 2D thermal analysis of the temperature distribution around the grain boundary. The 2D transient analysis shows that the temperature rise in the grain boundary of a sintered PM aluminum sample due to an electric pulse can exceed the melting point. At the same time the temperature of the bulk material has an insignificant (<28°C) change. It was found that the electroplastic effect, due to electric pulse application, can account for up to a 40% load drop in aluminum MMC PM compacts. Reduction of flow stresses during plastic deformation could reduce the risk of structural damage, micro-cracks, SiC particle fracture and delamination of the aluminum MMC. These results may find practical application for manufacturing processes such as forging, extrusion, rolling, which involve plastic deformation. It was experimentally proven that a non-uniform temperature distribution around the crack could re-melt the crack tip and increase the strength of the damaged material. The experimental study shows an increase in the stress intensity factor up to 76% for sintered aluminum PM compacts and up to 116% for sintered aluminum MMC PM compacts due to application of high-density electric pulses during transverse rapture testing.

  1. -OK 8>00jigLi Metallurgy Department

    E-print Network

    of Metallic and Ceramic Composites. 9. Risø International Symposium on Metallurgy and Materials Science, Risø onfibrecomposite materials. The course was developed for Dansk Metalarbejderforbund (The Danish Metal Workers-OK 8°>00jigLi 00 tf) Risø-M-28B Metallurgy Department Publications 1988 Risø National Laboratory

  2. Synergism Between Chemistry and Metallurgy for Invention

    NASA Astrophysics Data System (ADS)

    McKaveney, J. P.

    1987-03-01

    This paper discusses the development of corrosion resistant and electrically conductive coatings based on physical property behavior learned from steel industry research. Commercial ferroalloys have been used to replace zinc and pure metal powders in these applications. In the first instance, an in-situ hydrolysis of the paint binder and subsequent reaction with ferroalloy alkali oxides produces an insoluble, adhefent barrier film. In the latter case, the platelet type structure of the ferroalloy powders maintains metal contact better than spherical pure metal powders when mixed with PVC binders.

  3. Fluidized reduction of oxides on fine metal powders without sintering

    NASA Technical Reports Server (NTRS)

    Hayashi, T.

    1985-01-01

    In the process of reducing extremely fine metal particles (av. particle size or = 1000 angstroms) covered with an oxide layer, the metal particles are fluidized by a gas flow contg. H, heated, and reduced. The method uniformly and easily reduces surface oxide layers of the extremely fine metal particles without causing sintering. The metal particles are useful for magnetic recording materials, conductive paste, powder metallurgy materials, chem. reagents, and catalysts.

  4. Compaction of Ductile and Fragile Grains

    NASA Astrophysics Data System (ADS)

    Creissac, S.; Pouliquen, O.; Dalloz-Dubrujeaud, B.

    2009-06-01

    The compaction of powders into tablets is widely used in several industries (cosmetics, food, pharmaceutics…). In all these industries, the composition of the initial powder is complex, and the behaviour under compaction is not well known, also the mechanical behaviour of the tablets. The aim of this paper is to understand the behaviour (pressure vs density) of a simplified media made of fragile and ductile powders, varying the relative ratio of each powder. Some compaction experiments were carried out with glass beads (fragile) and Polyethylen Glycol powder (ductile). We observe two typical behaviours, depending on the relative volumic fraction of each component. A transition is pointed out, observing the evolution of the slope of the curve pressure/density. This transition is explained by geometrical considerations during compaction. A model is proposed, based on the assumption that the studied media can be compare to a diphasic material with a continuous phase (the ductile powder) and a discrete phase (the fragile powder). The result of this model is compare to the experimental results of compaction, and give a good prediction of the behaviour of the different mixing, knowing the behaviour of the ductile and the fragile phase separately. These results were also interpreted in terms of Heckel parameter which characterizes the ability of the powder to deform plastically under compaction. Some mechanical tests were also performed to compare the mechanical resitance of the obtained tablets.

  5. Explosive consolidation of titanium-nickel shape-memory alloy from pure titanium powder and pure nickel powder

    Microsoft Academic Search

    T. C. Li; Y. B. Qui; J. T. Liu; F. T. Wang; M. Zhu; D. Z. Yang

    1992-01-01

    Increasing numbers of applications of shapememory alloys have been developed and the alloys that are most successfully used among the many kinds of shape-memory alloys are TiNi alloys. TiNi alloys have excellent mechanical properties and shape-memory effect. However, its high cost resulting from complicated melting and machining procedures has limited its application. By contrast, powder metallurgy is a method for

  6. Introduction to the physical metallurgy of welding

    SciTech Connect

    Esterling, K.E.

    1983-01-01

    This book presents a lucid examination of the physical metallurgy of welding. The author details the effect of the thermal weld cycle on the micro-structure and properties of fusion welds. For ease of reference, the book is divided into four sections. The first section provides a broad introduction to the many process variables in fusion welding. The next two sections deal with the weld deposit, including mechanisms of solidification, and the heat affected zone, which details effects of the weld thermal cycle on microstructure. The final section is concerned with cracking and fractures in welds. The book also includes a comprehensive case study of the ''Alexander Keilland'' North Sea accommodation platform disaster.

  7. High temperature shock consolidation of hard ceramic powders

    NASA Astrophysics Data System (ADS)

    Hokamoto, K.; Tanaka, S.; Fujita, M.; Itoh, S.; Meyers, M. A.; Chen, H.-C.

    1997-02-01

    High-temperature shoch consolidation of hard ceramic powders was used as a means to improve bonding between powders and to decrease the number of cracks generated in the consolidated sample. A converging underwater shock-wave assembly was used for the compaction, and TiB 2, c-BN and their mixed powders were consolidated at various conditions up to 850°C. The positive effects by heating the powders were confirmed by the experiments conducted.

  8. 1. Photocopy from J. L. Bray, The Principles of Metallurgy, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    1. Photocopy from J. L. Bray, The Principles of Metallurgy, Ginn & Company, New York, 1929 - International Smelting & Refining Company, Tooele Smelter, Sinter Plant, State Route 178, Tooele, Tooele County, UT

  9. Looking North into Lab Metallurgy Testing Area and Enrichment Motor ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Looking North into Lab Metallurgy Testing Area and Enrichment Motor within Recycle Recovery Building - Hematite Fuel Fabrication Facility, Recycle Recovery Building, 3300 State Road P, Festus, Jefferson County, MO

  10. Effects of chromium addition on the metallurgy and P/M processing response of Alumix 431D

    NASA Astrophysics Data System (ADS)

    Mosher, Michael Patrick

    The ever growing industry of Powder Metallurgy (P/M) is developing to include new alloys and improve those currently available. This project relates to the optimization of a commercially available Al-Zn-Mg-Cu based alloy (Alumix 431D). This alloy is the P/M equivalent of the wrought 7075 alloy, and yields some of the top performance found in any available aluminum alloy. Optimization of the alloy has been conducted with a focus on sintering conditions; in particular the effect of sintering temperature and post-sintering cooling. Five sintering temperatures were investigated and the optimal temperature was found to be 605°C. Cr was added in trace amounts as per literature recommendations in an attempt to improve corrosion resistance. Both the Cr-free and Cr-containing alloys were then assessed for post-sinter cooling effects. The Alumix 431D w/Cr compacted and sintered to a higher density which further resulted in improved hardness over the Cr-free counterpart. The cooling profile was modified to include an increasingly larger post-sinter furnace-cooling section, before gas quenching. Seven quenching temperatures were chosen to investigate ranging from the sintering temperature (605°C) down to 480°C. This furnace cooling allowed the alloy-rich liquid phase to dwell for an extended time at elevated temperature and thereby diffuse into the matrix grains increasing the alloy content. This was confirmed through EPMA and correlated with an increase in mechanical properties. For both alloys peak hardness was produced by specimens cooled to 520°C before quenching. Tensile strength also increased by as much as 12% when furnace cooled to 540°C. The heat treatment parameters were determined to yield an optimal T6 temper. Specimens of both alloys processed under all conditions were then subjected to this heat treatment and further characterized. Many of the improvements offered by furnace cooling that were obvious in the T1 'as-sintered' product, became less pronounced after heat treatment. Corrosion resistance was also studied and compared to the wrought 7075 equivalent. For 'as-sintered' P/M components the Tafel extrapolation was less effective in accurately determining corrosion rate due to the effect of porosity on surface area. To remedy this, samples were hot worked to near full density (>99.5% theoretical), heat treated and tested. The hot worked P/M samples performed up to 2x better than the wrought 7075 with respect to corrosion current densities.

  11. Stress analysis of lead-free solders with under bump metallurgy in a wafer level chip scale package

    Microsoft Academic Search

    S. C. Tseng; R. S. Chen; C. C. Lio

    2006-01-01

    The wafer level chip scale assembly (WLCSP) has increasingly become popular due to its compact, wafer scale assembly. In a WLCSP assembly, the under bump metallurgy (UBM) connecting the solder joints and the chip is crucial for the assembly reliability. This study focuses on a WLCSP with 96.5Sn3.5Ag\\/95.5Sn3.8Ag0.7Cu solder joints and Ti\\/Cu\\/Ni UBM on a 2–layer microvia build-up electric board.

  12. Synthesis and processing of monosized oxide powders

    DOEpatents

    Barringer, E.A.; Fegley, M.B. Jr.; Bowen, H.K.

    1985-09-24

    Uniform-size, high-purity, spherical oxide powders are formed by hydrolysis of alkoxide precursors in dilute alcoholic solutions. Under controlled conditions (concentrations of 0.03 to 0.2 M alkoxide and 0.2 to 1.5 M water, for example) oxide particles on the order of about 0.05 to 0.7 microns can be produced. Methods of doping such powders and forming sinterable compacts are also disclosed. 6 figs.

  13. Synthesis and processing of monosized oxide powders

    DOEpatents

    Barringer, Eric A. (Waltham, MA); Fegley, Jr., M. Bruce (Waban, MA); Bowen, H. Kent (Belmont, MA)

    1985-01-01

    Uniform-size, high-purity, spherical oxide powders are formed by hydrolysis of alkoxide precursors in dilute alcoholic solutions. Under controlled conditions (concentrations of 0.03 to 0.2 M alkoxide and 0.2 to 1.5 M water, for example) oxide particles on the order of about 0.05 to 0.7 micron can be produced. Methods of doping such powders and forming sinterable compacts are also disclosed.

  14. Microwave heating of conductive powder materials

    NASA Astrophysics Data System (ADS)

    Rybakov, K. I.; Semenov, V. E.; Egorov, S. V.; Eremeev, A. G.; Plotnikov, I. V.; Bykov, Yu. V.

    2006-01-01

    In recent years, a considerable interest has been drawn to microwave heating of powder metals and other electrically conductive materials. In this paper a consistent formulation describing the absorption of microwaves in electrically conductive materials under different microwave heating conditions is developed. A special case when conductive powder particles are surrounded by insulating oxide layers is investigated in detail using the effective-medium approximation. The conditions giving rise to skin effect governed, volumetric, and localized microwave heating are analyzed. Experimental observations of different microwave heating regimes in silicon, iron, and copper powder compacts are in general agreement with the theoretical model.

  15. 78 FR 8202 - Meeting of the Joint ACRS Subcommittees on Thermal Hydraulic Phenomena and Materials, Metallurgy...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-02-05

    ...ACRS) Meeting of the Joint ACRS Subcommittees on Thermal Hydraulic Phenomena and Materials, Metallurgy and Reactor Fuels; Notice of Meeting The Joint ACRS Subcommittees on Thermal Hydraulic Phenomena and Materials, Metallurgy and Reactor...

  16. Wet powder seal for gas containment

    DOEpatents

    Stang, Louis G. (Sayville, NY)

    1982-01-01

    A gas seal is formed by a compact layer of an insoluble powder and liquid filling the fine interstices of that layer. The smaller the particle size of the selected powder, such as sand or talc, the finer will be the interstices or capillary spaces in the layer and the greater will be the resulting sealing capacity, i.e., the gas pressure differential which the wet powder layer can withstand. Such wet powder seal is useful in constructing underground gas reservoirs or storage cavities for nuclear wastes as well as stopping leaks in gas mains buried under ground or situated under water. The sealing capacity of the wet powder seal can be augmented by the hydrostatic head of a liquid body established over the seal.

  17. Infiltration kinetics of aluminum in silicon carbide compacts. Annual report

    Microsoft Academic Search

    G. R. Edwards; D. L. Olson

    1987-01-01

    Although metal-matrix composites have been fabricated by various techniques, the most successful are solid state processes such as powder metallurgy and diffusion bonding. Liquid-metal processes such as compucasting, pultrusion, and infiltration, while less successful, are potentially more economical. The advantages of producing silicon carbide-aluminum matrix composites by liquid-metal infiltration techniques can not be fully realized without an improved understanding of

  18. Adventures in the physical metallurgy of steels H. K. D. H. Bhadeshia

    E-print Network

    Cambridge, University of

    Preface Adventures in the physical metallurgy of steels H. K. D. H. Bhadeshia Department of Materials Science and Metallurgy, University of Cambridge, Cambridge CB3 0FS, UK, email hkdb a template for meetings of the future. Attendance at `Adventures in the physical metallurgy of steels' (APMS

  19. C T D ) T T ( ^ / S ^ \\ / Ris-R-473 Metallurgy Department

    E-print Network

    t C T D ) T T ( ^ / S ^ \\ / Ris»-R-473 Metallurgy Department Progress Report for tbe Period 1 of the Metallurgy Department at Risø during 1981 are described. The work is presented in three chap- ters: General-descriptors; FUEL ELEMENTS, METALLURGY, NONDESTRUCTIVE TESTING, RESEARCH PROGRAMS, RISOE NATIONAL LABORATORY. UDC

  20. A comparison of the sintering of various titanium powders

    SciTech Connect

    Gerdemann, Stephen J.; Alman, David E.

    2005-02-01

    Recently, there has been renewed interest in low-cost titanium. Near-net-shape powder metallurgy offers the potential of manufacturing titanium articles without costly and difficult forming and machining operations; hence, processing methods such as conventional press- and-sinter, powder forging and powder injection molding are of interest. The sintering behavior of a variety of commercial and experimental titanium powders was studied. Commercial powders were acquired that were produced different routes: (i) sponge fines from the primary titanium processing; (ii) via the hydride-dehydride process; and (iii) gas atomization. The influence of vacuum sintering time (0.5 to 32 hrs) and temperature (1200, 1275 or 1350°C) on the microstructure (porosity present) of cold pressed powders was studied. The results are discussed in terms of the difference in powder characteristics; with the aim of identify the characteristics required for full density via press-and-sinter processing. Near-net-shape tensile bars were consolidated via cold pressed and sintered. After sintering, a sub-set of the tensile bars was hot-isostatic pressed (HIPed). The microstructure and properties of the bars were compared in the sintered and HIPed conditions.

  1. Powder treatment process

    DOEpatents

    Weyand, J.D.

    1988-02-09

    Disclosed are: (1) a process comprising spray drying a powder-containing slurry, the slurry containing a powder constituent susceptible of oxidizing under the temperature conditions of the spray drying, while reducing the tendency for oxidation of the constituent by including as a liquid constituent of the slurry an organic liquid; (2) a process comprising spray drying a powder-containing slurry, the powder having been pretreated to reduce content of a powder constituent susceptible of oxidizing under the temperature conditions of the spray drying, the pretreating comprising heating the powder to react the constituent; and (3) a process comprising reacting ceramic powder, grinding the reacted powder, slurrying the ground powder, spray drying the slurried powder, and blending the dried powder with metal powder. 2 figs.

  2. Powder treatment process

    DOEpatents

    Weyand, John D. (Greensburg, PA)

    1988-01-01

    (1) A process comprising spray drying a powder-containing slurry, the slurry containing a powder constituent susceptible of oxidizing under the temperature conditions of the spray drying, while reducing the tendency for oxidation of the constituent by including as a liquid constituent of the slurry an organic liquid; (2) a process comprising spray drying a powder-containing slurry, the powder having been pretreated to reduce content of a powder constituent susceptible of oxidizing under the temperature conditions of the spray drying, the pretreating comprising heating the powder to react the constituent; and (3) a process comprising reacting ceramic powder, grinding the reacted powder, slurrying the ground powder, spray drying the slurried powder, and blending the dried powder with metal powder.

  3. Mach stem characterization in Mbar designs using RSR powder

    SciTech Connect

    Staudhammer, K.P.; Johnson, K.A.

    1985-01-01

    Suitable selection of powders can be used as a modeling device for complicated experimental designs. The powder melt zone is clearly defined and the RSR-834 powder is reasonably well behaved. This experiment was with only one composition, size and distribution. However, it is believed that other morphologies, composition, and size distributions could result in a more complete modeling of the compaction process that would enable heuristic calculations of the combined effects of adiabatic temperature rise and entropic heating (strain/deformation).

  4. Modeling density contributions in preceramic polymer\\/ceramic powder systems

    Microsoft Academic Search

    K. B. Schwartz; D. J. Rowcliffe

    1986-01-01

    A model is presented that examines the mixing of ceramic powders with preceramic polymer binders that are converted to ceramic material on pyrolysis. Such polymer\\/powder systems, which have applications in the compaction of both SiC and Si3N4 powders, can be effective in increasing the green density of die-pressed bodies. This model examines the relative importance of various physical parameters of

  5. Problems of powder flow in tabletting processes

    Microsoft Academic Search

    J. A. Hersey

    1965-01-01

    Summary The flow of non-compacted granules in the tablet machine hopper is discussed with relevance to the unit dose of drug, which is required to be dispensed. The various factors used to describe powder flow such as angle of repose, interparticulate cohesion and friction, flow through apertures, bulk density and die fillability are considered. The effects of humidity and of

  6. 39. GENERAL VIEW LOOKING NORTH, SHOWING BUILDING NO. 318, METALLURGY ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    39. GENERAL VIEW LOOKING NORTH, SHOWING BUILDING NO. 318, METALLURGY LAB, ON RIGHT, BUILDING NO. 319, GENERAL PURPOSE ADMINISTRATION BUILDING, ON LEFT AND BUILDING NO. 355, ADMINISTRATION BUILDING, RESEARCH & DEVELOPMENT, IN BACKGROUND LEFT. - Picatinny Arsenal, State Route 15 near I-80, Dover, Morris County, NJ

  7. Chemical and Metallurgy Research (CMR) Sample Tracking System Design Document

    SciTech Connect

    Bargelski, C. J.; Berrett, D. E.

    1998-09-01

    The purpose of this document is to describe the system architecture of the Chemical and Metallurgy Research (CMR) Sample Tracking System at Los Alamos National Laboratory. During the course of the document observations are made concerning the objectives, constraints and limitations, technical approaches, and the technical deliverables.

  8. Materials and Metallurgy Materials Science and Metallurgical Engineering

    E-print Network

    Provancher, William

    Materials and Metallurgy Materials Science and Metallurgical Engineering Objective Students "Rocks and Materials Science" Presentation. Review uses of rocks. Explain that engineers extract will learn about raw materials and where they come from. Standards and Objectives · 7th Grade Standard 1

  9. The mysterious world of plutonium metallurgy: Past and future

    Microsoft Academic Search

    S. S. Hecker; E. F. Hammel

    1998-01-01

    The first atomic bomb detonated at the Trinity Site in New Mexico on July 16, 1945, used plutonium, a man-made element discovered < 5 yr earlier. The story of how Manhattan Project scientists and engineers tackled the mysteries of this element and fabricated it into the first atomic bomb is one of the most fascinating in the history of metallurgy

  10. Pipeline failure: The roles played by corrosion, flow and metallurgy

    SciTech Connect

    Paisley, D. [BP Exploration Alaska, Prudhoe Bay, AK (United States); Barrett, N. [BP Exploration Wytch Farm, Poole (United Kingdom); Wilson, O. [Andrew Palmer and Associates, Aberdeen (United Kingdom)

    1999-11-01

    Carbon dioxide corrosion has been widely studied in the field and laboratory. It is recognized that flow regime and metallurgy are important factors that influence in-situ corrosion rates but there are relatively few documented case studies that are able to separate the individual contributions of corrosion, flow regime and metallurgy on the observed corrosion damage. This paper deals with failure of a pipeline where high quality inspection data together with comprehensive as-built records and stable production conditions allowed the separate influences of flow and metallurgy on corrosion to be studied. The flow regimes in the pipeline ranged from low velocity, stratified flow to high velocity, slug flow. The inspection data showed that the affect of turbulent flow was to increase the frequency of corrosion pits and, in the case of weld corrosion, the mean corrosion rate. The pipeline was constructed from two grades of steel and welded using two types of welding consumable. One grade of pipeline steel corroded at a significantly higher rate and with a higher frequency of corrosion pits than another, apparently similar steel. However, no significant relationship was found between weld metallurgy and corrosion rate or frequency.

  11. Powder Metallurgy of Uranium Alloy Fuels for TRU-Burning Reactors; Final Technical Report

    Microsoft Academic Search

    Sean M. McDeavitt

    2011-01-01

    Overview;\\u000a;\\u000aFast reactors were evaluated to enable the transmutation of transuranic isotopes generated by nuclear energy systems. The motivation for this was that TRU isotopes have high radiotoxicity and relatively long half-lives, making them unattractive for disposal in a long-term geologic repository. Fast reactors provide an efficient means to utilize the energy content of the TRUs while destroying them.

  12. Claw pole armature permanent magnet machines exploiting soft iron powder metallurgy

    Microsoft Academic Search

    Alan G. Jack; Barrie C. Mecrow; Chris P. Maddison; Norhasbi Abdul Wahab

    1997-01-01

    This paper describes a novel permanent magnet machine which uses a claw pole topology in the armature to produce a high performance machine. This machine is almost impossible to construct from laminated material, therefore a soft magnetic composite has been employed throughout the stator. The paper gives details of the constructional features and presents performance measurements for this machine

  13. Utilization of Space Shuttle External Tank materials by melting and powder metallurgy

    NASA Technical Reports Server (NTRS)

    Chern, T. S.

    1985-01-01

    The Crucible Melt Extraction Process was demonstrated to convert scraps of aluminum alloy 2219, used in the Space Shuttle External Tank, into fibers. The cast fibers were then consolidated by cold welding. The X-ray diffraction test of the cast fibers was done to examine the crystallinity and oxide content of the fibers. The compressive stress-strain behavior of the consolidated materials was also examined. Two conceptual schemes which would adapt the as-developed Crucible Melt Extraction Process to the microgravity condition in space were finally proposed.

  14. Stress corrosion evaluation of powder metallurgy aluminum alloy 7091 with the breaking load test method

    NASA Technical Reports Server (NTRS)

    Domack, Marcia S.

    1987-01-01

    The stress corrosion behavior of the P/M aluminum alloy 7091 is evaluated in two overaged heat treatment conditions, T7E69 and T7E70, using an accelerated test technique known as the breaking load test method. The breaking load data obtained in this study indicate that P/M 7091 alloy is highly resistant to stress corrosion in both longitudinal and transverse orientations at stress levels up to 90 percent of the material yield strength. The reduction in mean breaking stress as a result of corrosive attack is smallest for the more overaged T7E70 condition. Details of the test procedure are included.

  15. Wear resistant tools for reproduction technologies produced by micro powder metallurgy

    Microsoft Academic Search

    A. Rota; T.-V. Duong; T. Hartwig

    2002-01-01

    Micro system technology (MST) needs cost effective production techniques and for the development of new MST products also\\u000a new materials are necessary. Reproduction technologies have been developed for large scale production which are allow processing\\u000a a broad scope of materials (plastic, ceramic and metal). For these, tools are needed which have to fulfil a lot of requirements.\\u000a In this paper

  16. Effects of thermally induced porosity on an as-HIP powder metallurgy superalloy

    NASA Technical Reports Server (NTRS)

    Dreshfield, R. L.; Miner, R. V., Jr.

    1980-01-01

    The effect of thermally induced porosity on the mechanical properties of an as-hot-isostatically pressed and heat-treated pressing made from low carbon Astroloy is examined. Tensile, stress-rupture, creep, and low cycle fatigue tests were performed and the results were compared with industrial acceptance criteria. It is shown that the porous pressing has a porosity gradient from the rim to the bore with the bore having 1-1/2% greater porosity. Mechanical properties of the test ring below acceptance level are tensile reduction in area at room temperature and 538 C and time for 0.1% creep at 704 C. It is also found that the strength, ductility, and rupture life of the rim are slightly inferior to those of the rim of the sound pressings, while those of the bore are generally below the acceptable level. At strain ranges typical of commercial aircraft engines, the low cycle fatigue life of the rim of the porous pressings is slightly lower than that of the sound pressings.

  17. Interfacial design of Cu-based composites prepared by powder metallurgy for heat sink applications

    Microsoft Academic Search

    Th. Schubert; B. Trindade; T. Weißgärber; B. Kieback

    2008-01-01

    Thermal aspects are becoming increasingly important for the reliability of the electronic components due to the continuous progress of the electronic industries. Therefore, the effective thermal management is a key issue for packaging of high performance semiconductors. The ideal material working as heat sink and heat spreader should have a CTE of (4–8)×10?6K?1 and a high thermal conductivity. Metal matrix

  18. Reduction of porosity in oxide dispersion-strengthened alloys produced by powder metallurgy

    Microsoft Academic Search

    Y. L. Chen; A. R. Jones

    2001-01-01

    In this work, the porosity in a iron-based oxide dispersion-strengthened (ODS) alloy, namely, PM2000, has been studied together\\u000a with its recrystallization behavior. It has been found that pores are only found in coarse secondary recrystallized grains\\u000a formed at the early stage of recrystallization. It is suggested that a lack of fast diffusion paths, particularly grain boundaries,\\u000a will prevent gas trapped

  19. Indentation creep study on ultrafine-grained Zn processed by powder metallurgy

    E-print Network

    Gubicza, Jenõ

    in the homologous temperature range of 0.87­0.91. The activation energy of the creep for UFG-Zn was found to be much during creep deformation, indicating a considerable dislocation activity. & 2013 Elsevier B.V. All rights reserved. 1. Introduction The deformation mechanisms in hexagonal close-packed (hcp) metals depend strongly

  20. SiC particle cracking in powder metallurgy processed aluminum matrix composite materials

    Microsoft Academic Search

    B. Wang; G. M. Janowski; B. R. Patterson

    1995-01-01

    Particle cracking is one of the key elements in the fracture process of particulate-reinforced metal-matrix composite (MMC)\\u000a materials. The present study quantitatively examined the amount of new surface area created by particle cracking and the number\\u000a fraction of cracked particles in a series of SiC-reinforced aluminum-matrix composite materials. These composite materials\\u000a were fabricated by liquid-phase sintering and contained 9 vol

  1. SiC particle cracking in powder metallurgy processed aluminum matrix composite materials

    Microsoft Academic Search

    B. Wang; G. M. Janowski; B. R. Patterson

    1995-01-01

    Particle cracking is one of the key elements in the fracture process of particulate-reinforced metal-matrix composite (MMC) materials. The present study quantitatively examined the amount of new surface area created by particle cracking and the number fraction of cracked particles in a series of SiC-reinforced aluminum-matrix composite materials. These composite materials were fabricated by liquid-phase sintering and contained 9 vol

  2. PTFE distribution across the wall thickness of an impregnated powder metallurgy bushing

    Microsoft Academic Search

    S. G. Medvedev

    1972-01-01

    1.A study was made of the parameters of impregnation of porous sintered iron materials by the method of application of excess pressure.2.A technique has been developed for investigating the distribution of PTFE across the wall thickness of porous sintered bushings impregnated with this polymer.

  3. In vitro degradation and cytotoxicity of Mg/Ca composites produced by powder metallurgy q

    E-print Network

    Zheng, Yufeng

    alloy materials, such as bulk materials (AZ31 [1,2], AZ91 [1,2], Mg­Ca [3], Mg­Mn­Zn [4], etc.), AZ91D scaffolds [6,7], AZ91D/HA composite [8] and calcium phosphate coated Mg alloys [9,10]. Composite materials have been developed as an alternative for obtaining materials with high stiffness, wear resistance

  4. Development of powder metallurgy 2XXX series Al alloys for high temperature aircraft structural applications

    NASA Technical Reports Server (NTRS)

    Chellman, D. J.

    1984-01-01

    The objective of the present investigation was to improve the strength and fracture toughness combination of P/M 2124 Al alloys in accordance with NASA program goals for damage tolerance and fatigue resistance. Two (2) P/M compositions based on Al-3.70 Cu-1.85 Mg-0.20 Mn with 0.12 and 0.60 wt. pct. Zr were selected for investigation. The rapid solidification rates produced by atomization were observed to prohibit the precipitation of coarse, primary Al3Zr in both alloys. A major portion of the Zr precipitated as finely distributed, coherent Al3Zr phases during vacuum preheating and solution heat treatment. The proper balance between Cu and Mg contents eliminated undissolved, soluble constituents such as Al2CuMg and Al2Cu during atomization. The resultant extruded microstructures produced a unique combination of strength and fracture toughness. An increase in the volume fraction of coherent Al3Zr, unlike incoherent Al20Cu2Mn3 dispersoids, strengthened the P/M Al base alloy either directly by dislocation-precipitate interactions, indirectly by a retardation of recrystallization, or a combination of both mechanisms. Furthermore, coherent Al3Zr does not appear to degrade toughness to the extent that incoherent Al20Cu2Mn3 does. Consequently, the addition of 0.60 wt. pct. Zr to the base alloy, incorporated with a 774K (935 F) solution heat treatment temperature, produces an alloy which exceeds all tensile property and fracture toughness goals for damage tolerant and fatigue resistant applications in the naturally aged condition.

  5. Canning Of Powdered Metal For Hot Isostatic Pressing

    NASA Technical Reports Server (NTRS)

    Juhas, John J.

    1989-01-01

    Quality of specimen enhanced by improved canning process. Method developed for canning specimens for hot isostatic pressing. Specimen placed inside refractory-metal ring, then sandwiched between two refractory-metal face sheets. Assembly placed inside die, then positioned in vacuum hot press. Heated to set temperature at prescribed vacuum to burn off all of binder in specimen. Advantages: powder-metallurgy composite totally purged of binder sealed in can in single operation, maintains size, shape, and uniformity of specimen. Weld region does not recrystallize, and little possibility of cracking.

  6. Magnetic Properties of Amorphous Fe-Si-B Powder Cores Mixed with Pure Iron Powder

    NASA Astrophysics Data System (ADS)

    Kim, Hyeon-Jun; Nam, Seul Ki; Kim, Kyu-Sung; Yoon, Sung Chun; Sohn, Keun-Yong; Kim, Mi-Rae; Sul Song, Yong; Park, Won-Wook

    2012-10-01

    Amorphous Fe-Si-B alloy was prepared by melt-spinning, and then the ribbons were pulverized and ball-milled to make the amorphous powder of ˜25 µm in size. Subsequently those were mixed with pure iron powders with an average particle size of 3 µm, and 1.5 wt % water glass diluted by distilled water at the ratio of 1:2. The powder mixtures were cold compacted at 650 MPa in toroid die, and heat treated at 430-440 °C under a nitrogen atmosphere for 1 h and 30 min, respectively. The soft magnetic properties of powder core were investigated using a B-H analyzer and a flux meter at the frequency range of ˜100 kHz. The microstructure was observed using scanning electron microscope (SEM), and the density of the core was measured using the principle of Archimedes. Based on the experimental results, the amorphous powder mixed with pure iron powder showed the improved powder compactability, which resulted in the increased permeability and the reduced core loss.

  7. Characterization of Fine Powders

    NASA Astrophysics Data System (ADS)

    Krantz, Matthew; Zhang, Hui; Zhu, Jesse

    Fine powders are used in many applications and across many industries such as powdered paints and pigments, ceramics, petrochemicals, plastics, pharmaceuticals, and bulk and fine chemicals, to name a few. In addition, fine powders must often be handled as a waste by-product, such as ash generated in combustion and gasification processes. In order to correctly design a process and process equipment for application and handling of powders, especially fine powders, it is essential to understand how the powder would behave. Many characterization techniques are available for determining the flow properties of powders; however, care must be taken in selecting the most appropriate technique(s).

  8. Polymer quenched prealloyed metal powder

    DOEpatents

    Hajaligol, Mohammad R. (Midlothian, VA); Fleischhauer, Grier (Midlothian, VA); German, Randall M. (State College, PA)

    2001-01-01

    A powder metallurgical process of preparing a sheet from a powder having an intermetallic alloy composition such as an iron, nickel or titanium aluminide. The sheet can be manufactured into electrical resistance heating elements having improved room temperature ductility, electrical resistivity, cyclic fatigue resistance, high temperature oxidation resistance, low and high temperature strength, and/or resistance to high temperature sagging. The iron aluminide has an entirely ferritic microstructure which is free of austenite and can include, in weight %, 4 to 32% Al, and optional additions such as .ltoreq.1% Cr, .gtoreq.0.05% Zr .ltoreq.2% Ti, .ltoreq.2% Mo, .ltoreq.1% Ni, .ltoreq.0.75% C, .ltoreq.0.1% B, .ltoreq.1% submicron oxide particles and/or electrically insulating or electrically conductive covalent ceramic particles, .ltoreq.1% rare earth metal, and/or .ltoreq.3 % Cu. The process includes forming a non-densified metal sheet by consolidating a powder having an intermetallic alloy composition such as by roll compaction, tape casting or plasma spraying, forming a cold rolled sheet by cold rolling the non-densified metal sheet so as to increase the density and reduce the thickness thereof and annealing the cold rolled sheet. The powder can be a water, polymer or gas atomized powder which is subjecting to sieving and/or blending with a binder prior to the consolidation step. After the consolidation step, the sheet can be partially sintered. The cold rolling and/or annealing steps can be repeated to achieve the desired sheet thickness and properties. The annealing can be carried out in a vacuum furnace with a vacuum or inert atmosphere. During final annealing, the cold rolled sheet recrystallizes to an average grain size of about 10 to 30 .mu.m. Final stress relief annealing can be carried out in the B2 phase temperature range.

  9. Process for synthesizing compounds from elemental powders and product

    DOEpatents

    Rabin, Barry H. (Idaho Falls, ID); Wright, Richard N. (Idaho Falls, ID)

    1993-01-01

    A process for synthesizing intermetallic compounds from elemental powders. The elemental powders are initially combined in a ratio which approximates the stoichiometric composition of the intermetallic compound. The mixed powders are then formed into a compact which is heat treated at a controlled rate of heating such that an exothermic reaction between the elements is initiated. The heat treatment may be performed under controlled conditions ranging from a vacuum (pressureless sintering) to compression (hot pressing) to produce a desired densification of the intermetallic compound. In a preferred form of the invention, elemental powders of Fe and Al are combined to form aluminide compounds of Fe.sub.3 Al and FeAl.

  10. Applications of lasers in machine building and metallurgy

    NASA Astrophysics Data System (ADS)

    Panchenko, Vladislav Y.; Golubev, Vladimir S.

    2000-07-01

    The current level of laser technology development and understanding of the process of laser radiation interaction with materials, attained by the world laser research community, including the scientists from Russian and from the IPLIT RAN, particularly, provides new possibilities of updating the technology of materials processing and diagnostics in machine-building and metallurgy. Several institutes of Russia, primarily the IPLIT RAN, develop and produce practically all basic types of industrial lasers used in materials processing. These lasers provide a basis for development and application of welding, cutting and surface treatment. Alongside with the above-listed traditional technologies of laser materials processing (LMP), a progress has been made in development of a new and promising laser-computer technology of 3D parts rapid prototyping. Besides, the laser-computer methods of non-contact diagnostics of subsurface defects and stressed states are of great interest to machine-building and metallurgy.

  11. Reliability comparison of two metallurgies for ceramic ball grid array

    Microsoft Academic Search

    D. R. Banks; T. E. Burnette; R. D. Gerke; E. Mammo; S. Mattay

    1995-01-01

    Surface-mountable ceramic ball grid array (CBGA) packages have proven to be attractive in a variety of applications as designers seek to maximize electrical performance, reduce card real estate, and improve manufacturing process yields. In support of the PowerPC family of microprocessors, 21 mm CBGA packages (256 leads) were used to evaluate two different ball metallurgies-90\\/10 Pb\\/Sn and 62\\/36\\/2 Sn\\/Pb\\/Ag. Test

  12. TT^T7Gs!rf5ft Riso-R-425 Metallurgy Department

    E-print Network

    CM tf TT^T7Gs!rf5ft Riso-R-425 (O O o o o \\l O Metallurgy Department Progress Report for the Period-R-425 METALLURGY DEPARTMENT PROGRESS REPORT FOR THE PERIOD 1 JANUARY TO 31 DECEMBER 1979 Abstract. The activities of the Metallurgy Department at Risø during 1979 are described. The work is presented in four chap

  13. Cairo to Cape: The Spread of Metallurgy Through Eastern and Southern Africa

    Microsoft Academic Search

    David Killick

    2009-01-01

    This article traces the beginnings of metallurgy in the eastern half of the African continent, focusing on three regions:\\u000a (1) Egypt and Nubia; (2) the Great Lakes region of Central and East Africa; and (3) southern Africa. Metallurgy was not practiced\\u000a much beyond the Nile valley until the first millennium BC, when copper, bronze and iron metallurgy began in Ethiopia

  14. Oxidized Metal Powders for Mechanical Shock and Crush Safety Enhancers

    SciTech Connect

    GARINO, TERRY J.

    2002-01-01

    The use of oxidized metal powders in mechanical shock or crush safety enhancers in nuclear weapons has been investigated. The functioning of these devices is based on the remarkable electrical behavior of compacts of certain oxidized metal powders when subjected to compressive stress. For example, the low voltage resistivity of a compact of oxidized tantalum powder was found to decrease by over six orders of magnitude during compaction between 1 MPa, where the thin, insulating oxide coatings on the particles are intact, to 10 MPa, where the oxide coatings have broken down along a chain of particles spanning the electrodes. In this work, the behavior of tantalum and aluminum powders was investigated. The low voltage resistivity during compaction of powders oxidized under various conditions was measured and compared. In addition, the resistivity at higher voltages and the dielectric breakdown strength during compaction were also measured. A key finding was that significant changes in the electrical properties persist after the removal of the stress so that a mechanical shock enhancer is feasible. This was verified by preliminary shock experiments. Finally, conceptual designs for both types of enhancers are presented.

  15. 3.40J / 22.71J Physical Metallurgy, Spring 2003

    E-print Network

    Russell, Kenneth

    Discusses structure-property relationships in metallic alloys selected to illustrate some basic concepts of physical metallurgy and alloy design. Fundamentals of annealing, spinodal decomposition, nucleation, growth, and ...

  16. Precision powder feeder

    DOEpatents

    Schlienger, M. Eric (Albuquerque, NM); Schmale, David T. (Albuquerque, NM); Oliver, Michael S. (Sandia Park, NM)

    2001-07-10

    A new class of precision powder feeders is disclosed. These feeders provide a precision flow of a wide range of powdered materials, while remaining robust against jamming or damage. These feeders can be precisely controlled by feedback mechanisms.

  17. NanoComposite Stainless Steel Powder Technologies

    SciTech Connect

    DeHoff, R.; Glasgow, C. (MesoCoat, Inc.)

    2012-07-25

    Oak Ridge National Laboratory has been investigating a new class of Fe-based amorphous material stemming from a DARPA, Defense Advanced Research Projects Agency initiative in structural amorphous metals. Further engineering of the original SAM materials such as chemistry modifications and manufacturing processes, has led to the development of a class of Fe based amorphous materials that upon processing, devitrify into a nearly homogeneous distribution of nano sized complex metal carbides and borides. The powder material is produced through the gas atomization process and subsequently utilized by several methods; laser fusing as a coating to existing components or bulk consolidated into new components through various powder metallurgy techniques (vacuum hot pressing, Dynaforge, and hot isostatic pressing). The unique fine scale distribution of microstructural features yields a material with high hardness and wear resistance compared to material produced through conventional processing techniques such as casting while maintaining adequate fracture toughness. Several compositions have been examined including those specifically designed for high hardness and wear resistance and a composition specifically tailored to devitrify into an austenitic matrix (similar to a stainless steel) which poses improved corrosion behavior.

  18. Amorphous powders of Al-Hf prepared by mechanical alloying

    SciTech Connect

    Schwarz, R.B.; Hannigan, J.W.; Sheinberg, H.; Tiainen, T.

    1988-01-01

    We synthesized amorphous Al/sub 50/Hf/sub 50/ alloy powder by mechanically alloying an equimolar mixture of crystalline powders of Al and Hf using hexane as a dispersant. We characterized the powder as a function of mechanical-alloying time by scanning electron microscopy, x-ray diffraction, and differential scanning calorimetry. Amorphous Al/sub 50/Hf/sub 50/ powder heated at 10 K s/sup /minus/1/ crystallizes polymorphously at 1003 K into orthorhombic AlHf (CrB-type structure). During mechanical alloying, some hexane decomposes and hydrogen and carbon are incorporated into the amorphous alloy powder. The hydrogen can be removed by annealing the powder by hot pressing at a temperature approximately 30 K below the crystallization temperature. The amorphous compacts have a diamond pyramidal hardness of 1025 DPH. 24 refs., 7 figs., 1 tab.

  19. Compact Storage

    USGS Multimedia Gallery

    After a detailed inventory is completed and published on the web, processed materials are stored in compact shelving in the Field Records Collection. Collections are organized by scientist and project....

  20. Mesoscale Simulations of Power Compaction

    SciTech Connect

    Lomov, I; Fujino, D; Antoun, T; Liu, B

    2009-08-06

    Mesoscale 3D simulations of metal and ceramic powder compaction in shock waves have been performed with an Eulerian hydrocode GEODYN. The approach was validated by simulating shock compaction of porous well-characterized ductile metal using Steinberg material model. Results of the simulations with handbook values for parameters of solid 2024 aluminum have good agreement with experimental compaction curves and wave profiles. Brittle ceramic materials are not so well studied as metals, so material model for ceramic (tungsten carbide) has been fitted to shock compression experiments of non-porous samples and further calibrated to match experimental compaction curves. Direct simulations of gas gun experiments with ceramic powder have been performed and showed good agreement with experimental data. Numerical shock wave profile has same character and thickness as measured with VISAR. Numerical results show reshock states above the single-shock Hugoniot line also observed in experiments. They found that to receive good quantitative agreement with experiment it is essential to perform 3D simulations.

  1. 1.Answer the following questions: (a)& you have learned in your physical metallurgy class, diffusion rate in solid may be

    E-print Network

    Huang, Haimei

    1.Answer the following questions: (a)& you have learned in your physical metallurgy class on the physical metallurgy principles, the student suggested two possibilities for the stress drop: 1) The stress

  2. Fe-based nanocrystalline powder cores with ultra-low core loss

    NASA Astrophysics Data System (ADS)

    Wang, Xiangyue; Lu, Zhichao; Lu, Caowei; Li, Deren

    2013-12-01

    Melt-spun amorphous Fe73.5Cu1Nb3Si15.5B7 alloy strip was crushed to make flake-shaped fine powders. The passivated powders by phosphoric acid were mixed with organic and inorganic binder, followed by cold compaction to form toroid-shaped bonded powder-metallurgical magnets. The powder cores were heat-treated to crystallize the amorphous structure and to control the nano-grain structure. Well-coated phosphate-oxide insulation layer on the powder surface decreased the the core loss with the insulation of each powder. FeCuNbSiB nanocrystalline alloy powder core prepared from the powder having phosphate-oxide layer exhibits a stable permeability up to high frequency range over 2 MHz. Especially, the core loss could be reduced remarkably. At the other hand, the softened inorganic binder in the annealing process could effectively improve the intensity of powder cores.

  3. Physical Chemistry and Process Dynamics of Reactions in Ladle Metallurgy

    NASA Astrophysics Data System (ADS)

    Fruehan, R. J.

    1985-03-01

    Ladle metallurgy practices have been developed that produce clean steels low in oxygen, sulfur, phosphorous and hydrogen. In addition, the remaining inclusions can be modified into less harmful forms. In this paper, the physical chemistry and process dynamics of the refining reactions are discussed. Optimum slag compositions for desulfurization and dephosphorization based on thermodynamic considerations are given. Reaction models have been developed to predict the rates of slag-metal reaction in stirred ladles. For inclusion removal, there is an optimum gas flow rate which is explained qualitatively. The rate equations for hydrogen and nitrogen removal under vacuum are also presented.

  4. Rigorous investigations of piecewise linear circuits Department of Electrical Engineering, University of Mining and Metallurgy,

    E-print Network

    Galias, Zbigniew

    , University of Mining and Metallurgy, al. Mickiewicza 30, 30­059 Krak´ow, POLAND e-mail: galias where the Poincar´e This work was supported by the University of Mining and Metallurgy, Krak´ow, grant

  5. Rigorous investigations of piecewise linear circuits # Department of Electrical Engineering, University of Mining and Metallurgy,

    E-print Network

    Galias, Zbigniew

    Engineering, University of Mining and Metallurgy, al. Mickiewicza 30, 30--059 Krakâ??ow, POLAND e­mail: galias where the Poincarâ??e # This work was supported by the University of Mining and Metallurgy, Krakâ??ow, grant

  6. Powder material parameters establishment through warm forming route

    Microsoft Academic Search

    M. M. Rahman; A. K. Ariffin; S. S. M. Nor; H. Y. Rahman

    2011-01-01

    This paper presents the establishment of the properties of powder materials through experimentation at elevated temperature ranging from room temperature (30°C) to 150°C. Uniaxial die compaction experiments were conducted to establish the powder properties such as densification, Young’s modulus, spring-back, plastic index, elastic index, and plastic hardening coefficient. Shearing experiments were conducted to establish the temperature dependent friction coefficient. Iron

  7. Characterisation of poly(methyl methacrylate) film deposited on iron powder particles by electropolymerization

    NASA Astrophysics Data System (ADS)

    Ori?ák, Andrej; Ori?áková, Renáta; Heile, Andreas; Talian, Ivan; Terhorst, Markus; Arlinghaus, Heinrich F.

    2007-09-01

    Iron powder microparticles were coated with a poly(methyl methacrylate) (PMMA) film by electropolymerization in a fluidised bed reactor. The formation of a PMMA coating on the microparticles' surface was studied with pyrolysis gas chromatography (Py-GC) fingerprinting as well as time-of-flight secondary ion mass spectrometry (TOF-SIMS). While Py-GC can provide information about PMMA bulk formation and quick information about PMMA deposition on iron microparticles, TOF-SIMS can give detailed information about particle surface PMMA coatings. A TOF-SIMS study was performed in both, positive and negative ion modes with Bi + and Bi3+ primary ions. Static TOF-SIMS macroscans of powder microparticle surface resulted in the identification of the regions with species related to the PMMA fragments in the negative ion region (Bi3+). TOF-SIMS results confirmed that PMMA coating on the iron powder microparticle surface formed an incoherent and inhomogeneous film. PMMA coating was somewhere very thin to supply a sufficient positive charged secondary ion signal. Plating of metallic powder particles by polymeric coating enables the modification of surface and structural properties of materials used in powder metallurgy. PMMA coated iron powder microparticles can be innovative as lubricants in such a way that, when they are subjected to pressure, they burst and release carbon to metal powder. The main aim of this research work is to characterise PMMA coatings deposited by electropolymerization on the surface of iron powder microparticles.

  8. Mechanical properties and shear failure surfaces of two alumina powders in triaxial compression

    SciTech Connect

    ZEUCH,DAVID H.; GRAZIER,J. MARK; ARGUELLO JR.,JOSE G.; EWSUK,KEVIN G.

    2000-04-24

    In the manufacture of ceramic components, near-net-shape parts are commonly formed by uniaxially pressing granulated powders in rigid dies. Density gradients that are introduced into a powder compact during press-forming often increase the cost of manufacturing, and can degrade the performance and reliability of the finished part. Finite element method (FEM) modeling can be used to predict powder compaction response, and can provide insight into the causes of density gradients in green powder compacts; however, accurate numerical simulations require accurate material properties and realistic constitutive laws. To support an effort to implement an advanced cap plasticity model within the finite element framework to realistically simulate powder compaction, the authors have undertaken a project to directly measure as many of the requisite powder properties for modeling as possible. A soil mechanics approach has been refined and used to measure the pressure dependent properties of ceramic powders up to 68.9 MPa (10,000 psi). Due to the large strains associated with compacting low bulk density ceramic powders, a two-stage process was developed to accurately determine the pressure-density relationship of a ceramic powder in hydrostatic compression, and the properties of that same powder compact under deviatoric loading at the same specific pressures. Using this approach, the seven parameters that are required for application of a modified Drucker-Prager cap plasticity model were determined directly. The details of the experimental techniques used to obtain the modeling parameters and the results for two different granulated alumina powders are presented.

  9. Problems of YAG nanopowders compaction for laser ceramics

    Microsoft Academic Search

    S. N. Bagayev; A. A. Kaminskii; Yu. L. Kopylov; V. B. Kravchenko

    2011-01-01

    Slip casting and colloidal slip casting at high pressure of yttrium aluminum garnet powders were investigated. It was found that the presence of residual pores in laser oxide ceramics was determined mainly by big size pores in the compact. The size of pore in compact is critical when it is greater than the mean size of initial particles. It was

  10. Oxide Dispersion Strengthened Iron Aluminide by CVD Coated Powders

    SciTech Connect

    Asit Biswas Andrew J. Sherman

    2006-09-25

    This I &I Category2 program developed chemical vapor deposition (CVD) of iron, aluminum and aluminum oxide coated iron powders and the availability of high temperature oxidation, corrosion and erosion resistant coating for future power generation equipment and can be used for retrofitting existing fossil-fired power plant equipment. This coating will provide enhanced life and performance of Coal-Fired Boilers components such as fire side corrosion on the outer diameter (OD) of the water wall and superheater tubing as well as on the inner diameter (ID) and OD of larger diameter headers. The program also developed a manufacturing route for readily available thermal spray powders for iron aluminide coating and fabrication of net shape component by powder metallurgy route using this CVD coated powders. This coating can also be applid on jet engine compressor blade and housing, industrial heat treating furnace fixtures, magnetic electronic parts, heating element, piping and tubing for fossil energy application and automotive application, chemical processing equipment , heat exchanger, and structural member of aircraft. The program also resulted in developing a new fabrication route of thermal spray coating and oxide dispersion strengthened (ODS) iron aluminide composites enabling more precise control over material microstructures.

  11. Effect of the characteristics of carbon-bearing charge components on the structure and properties of hot-worked powder steels: 1. Unconventional carbon-bearing components and their effect on charge preparation, pressing, and sintering

    SciTech Connect

    Dorofeev, Yu.G.; Dorofeev, V.Yu.; Eremeeva, Zh.V.; Goncharova, T.V. [Institute of Problems of Materials Science, Kiev (Ukraine)

    1995-03-01

    Conserving material resources, making the fullest possible use of raw materials, finding unconventional forms of raw materials, and creating waste-free technologies are among the ultimate goals of powder metallurgy. The use of industrial by-products saves resources while helping to make up for the shortage of raw materials for powder metallurgy. In the production of powder steels, these issues are central with respect to both the metallic and the carbon-bearing components of the charge. The optimum situation is when new (unconventional) carbon-bearing components (CBCs) not only save resources, but also possess properties superior to the components used previously. At present, various grades of natural graphite (pencil, foundry, electrical-carbon, lubricant) are the main CBCs used. Carbon black, sooty iron, and pig iron are also employed. IN the present study, carbon was introduced in the form of unconventional CBC`s into powder steels.

  12. The mysterious world of plutonium metallurgy: Past and future

    SciTech Connect

    Hecker, S.S.; Hammel, E.F. [Los Alamos National Lab., NM (United States)

    1998-12-31

    The first atomic bomb detonated at the Trinity Site in New Mexico on July 16, 1945, used plutonium, a man-made element discovered < 5 yr earlier. The story of how Manhattan Project scientists and engineers tackled the mysteries of this element and fabricated it into the first atomic bomb is one of the most fascinating in the history of metallurgy and materials. The authors are currently trying to generate renewed interest in plutonium metallurgy because of the challenge posed by President Clinton, i.e., to keep the nuclear stockpile of weapons safe and reliable without nuclear testing. The stockpile stewardship challenge requires either a lifetime extension of the plutonium components or a remanufacture--neither of which can be verified by testing. In turn, this requires that one achieve a better fundamental understanding of plutonium. Of special interest is the effect of self-irradiation on the properties and on the long-term stability of plutonium and its alloys. Additional challenges arise from long-term concerns about disposing of plutonium and dealing with its environmental legacy. It is imperative to interest the next generation of students in these plutonium challenges.

  13. Multiple feed powder splitter

    DOEpatents

    Lewis, Gary K. (Los Alamos, NM); Less, Richard M. (Los Alamos, NM)

    2002-01-01

    A device for providing uniform powder flow to the nozzles when creating solid structures using a solid fabrication system such as the directed light fabrication (DLF) process. In the DLF process, gas entrained powders are passed through the focal point of a moving high-power laser light which fuses the particles in the powder to a surface being built up in layers. The invention is a device providing uniform flow of gas entrained powders to the nozzles of the DLF system. The device comprises a series of modular splitters which are slidably interconnected and contain an integral flow control mechanism. The device can take the gas entrained powder from between one to four hoppers and split the flow into eight tubular lines which feed the powder delivery nozzles of the DLF system.

  14. Which Powder is It?

    NSDL National Science Digital Library

    Sciencenter

    2014-08-27

    In this chemistry challenge, learners identify an unknown white powder by comparing it with common household powders. Learners first explore what happens when baking soda, baking powder, and washing soda are mixed with water, vinegar, and PHTH (the indicator phenolphthalein mixed with alcohol and water). Learners then work to identify the unknown based on how it reacts with the known solutions. This is a simplified form of "qualitative analysis," which was historically an important approach chemists used for identifying unknown samples.

  15. Implications of elastic wave velocities for Apollo 17 rock powders

    NASA Technical Reports Server (NTRS)

    Talwani, P.; Nur, A.; Kovach, R. L.

    1974-01-01

    Ultrasonic P- and S-wave velocities of lunar rock powders 172701, 172161, 170051, and 175081 were measured at room temperature and to 2.5 kb confining pressure. The results compare well with those of terrestrial volcanic ash and powdered basalt. P-wave velocity values up to pressures corresponding to a lunar depth of 1.4 km preclude cold compaction alone as an explanation for the observed seismic velocity structure at the Apollo 17 site. Application of small amounts of heat with simultaneous application of pressure causes rock powders to achieve equivalence of seismic velocities for competent rocks.

  16. A self-propagating high-temperature synthesis method for synthesis of zinc oxide powder

    Microsoft Academic Search

    Chyi-Ching Hwang; Cheng-Shiung Lin; Gaw-Pying Wang; Cheng-Hsiung Peng; Shyan-Lung Chung

    2009-01-01

    A self-propagating high-temperature synthesis (SHS) method has been developed for synthesis of ZnO powder. Powders of Zn and an appropriate amount of NH4NO3 were mixed and pressed into a compact place in a closed chamber with air atmosphere. The combustion reaction was ignited by heating the reactant compact directly using nichrome coil, and then as-synthesized products mainly composed of tetrapod

  17. Powder processing and properties of zircon-reinforced Al-13.5Si-2.5Mg alloy composites

    SciTech Connect

    Ejiofor, J.U.; Reddy, R.G. [Univ. of Alabama, Tuscaloosa, AL (United States). Dept. of Metallurgical and Materials Engineering; Okorie, B.A. [Enugu State Univ. of Technology (Nigeria). Dept. of Metallurgical and Materials Engineering

    1997-06-01

    Zircon, ZrSiO{sub 4}, is a thermally stable mineral requiring expensive and energy-intensive process to reduce. Owing to its abundance, high hardness, excellent abrasion/wear resistance, and low coefficient of thermal expansion, a low-cost alternative use of the mineral for medium-strength tribology was investigated. The present study has developed a conventional low-cost, double-compaction powder metallurgy route in the synthesis of Al-13.5Si-2.5Mg alloy reinforced with zircon. The mechanical and physical properties were determined following the development of optimum conditions of cold pressing and reaction sintering. Reinforcing the hypereutectic Al-Si alloy with 15 vol% zircon particles (size <200 {micro}m) and cold pressing at 350 MPa to near-net shape, followed by liquid-phase reaction sintering at 615 C in vacuum for 20 min, improved the ultimate tensile strength, 0.2% yield strength, and hardness of the alloy by 4, 12.8, and 88%, respectively. At values of more than 9 vol% zircon, percent elongation and the dimensional changes of the sintered composites remained virtually unchanged. At a critical volume fraction of zircon, between 0.03 and 0.05, a sharp rise in hardness was observed. Microstructural and mechanical property analysis showed that the improvement in the mechanical properties is attributable largely to the load-bearing ability and intrinsic hardness of zircon, rather than to particulate dispersion effects. A good distribution of the dispersed zircon particulates in the matrix alloy was achieved.

  18. Physical and mechanical metallurgy of high purity Nb accelerator cavities.

    SciTech Connect

    Wright, N. T.; Bieler, T. R.; Pourgoghart , F.; Compton, C.; Hartwig, K. T.; Baars, D.; Zamiri, A.; Chandrasekaran, S.; Darbandi, P.; Jiang, H.; Skoug, E.; Balachandran, S.; Ice, G. E.; Liu, W.; Michigan State Univ.; Texas A & M Univ.; ORNL

    2010-01-01

    In the past decade, high Q values have been achieved in high purity Nb superconducting radio frequency (SRF) cavities. Fundamental understanding of the physical metallurgy of Nb that enables these achievements is beginning to reveal what challenges remain to establish reproducible and cost-effective production of high performance SRF cavities. Recent studies of dislocation substructure development and effects of recrystallization arising from welding and heat treatments and their correlations with cavity performance are considered. With better fundamental understanding of the effects of dislocation substructure evolution and recrystallization on electron and phonon conduction, as well as the interior and surface states, it will be possible to design optimal processing paths for cost-effective performance using approaches such as hydroforming, which minimizes or eliminates welds in a cavity.

  19. Compact HPD

    SciTech Connect

    Suyama, M.; Kawai, Y.; Kimura, S. [Hamamatsu Photonics K.K., Shizuoka (Japan)] [and others

    1996-12-31

    In order to be utilized in such application fields as high energy physics or medical imaging, where a huge number of photodetectors are assembled in designated small area, the world`s smallest HPD, the compact BFD, has been developed. The overall diameter and the length of the tube are 16mm and 15mm, respectively. The effective photocathode area is 8mm in diameter. At applied voltage of -8kV to the photocathode, the electron multiplication gain of a PD incorporated HPD (PD-BPD) is 1,600, and that of an APD (APD-BPD) is 65,000. In the pulse height distribution measurement, photoelectron peaks up to 6 photoelectrons are clearly distinguishable with the APD-BPD. Experiments established that there was no degradation of gain in magnetic fields up to 1.5T, an important performance characteristic of the compact BPD for application in high energy physics.

  20. Technology Selections for Cylindrical Compact Fabrication

    SciTech Connect

    Jeffrey A. Phillips

    2010-10-01

    A variety of process approaches are available and have been used historically for manufacture of cylindrical fuel compacts. The jet milling, fluid bed overcoating, and hot press compacting approach being adopted in the U.S. AGR Fuel Development Program for scale-up of the compacting process involves significant paradigm shifts from historical approaches. New methods are being pursued because of distinct advantages in simplicity, yield, and elimination of process mixed waste. Recent advances in jet milling technology allow simplified dry matrix powder preparation. The matrix preparation method is well matched with patented fluid bed powder overcoating technology recently developed for the pharmaceutical industry and directly usable for high density fuel particle matrix overcoating. High density overcoating places fuel particles as close as possible to their final position in the compact and is matched with hot press compacting which fully fluidizes matrix resin to achieve die fill at low compacting pressures and without matrix end caps. Overall the revised methodology provides a simpler process that should provide very high yields, improve homogeneity, further reduce defect fractions, eliminate intermediate grading and QC steps, and allow further increases in fuel packing fractions.

  1. A preliminary concrete mix design for SCC with marble powders

    Microsoft Academic Search

    Kür?at Esat Alyamaç; Ragip Ince

    2009-01-01

    The marble has been commonly used as a building material since ancient times. Disposal of the waste materials of the marble industry, consisting of very fine powders, is one of the environmental problems worldwide today. However, these waste materials can be successfully and economically utilized to improve some properties of fresh and hardened self-compacting concrete (SCC).The aim of this study

  2. Compact groups of compact galaxies. IV. [Listing

    Microsoft Academic Search

    Petrosyan

    1974-01-01

    A fourth list of compact groups of compact galaxies is presented. It contains 37 new objects discovered in the Palomar Sky Survey Charts. The regions +90°, +84°, +78°, +0° are completely covered. Photographs of the compact groups of compact galaxies taken from the Palomar charts are appended.

  3. NMT-7 APPROACH TO WASTE MANAGEMENT AT LOS ALAMOS NATIONAL LABORATORY'S CHEMISTRY AND METALLURGY RESEARCH FACILITY

    Microsoft Academic Search

    Edward D. Derr; Ronald E. Wieneke

    2000-01-01

    The Chemistry and Metallurgy Research (CMR) Facility at Los Alamos National Laboratory (LANL) is a 550,000-square-foot building that was constructed in 1952, to house research and experimental facilities for analytical chemistry, plutonium and uranium chemistry, metallurgy, engineering design and drafting, electronics, and other support functions. Operations conducted within this diverse facility generate significant volumes of a wide range of hazardous,

  4. Compact magnetograph

    NASA Technical Reports Server (NTRS)

    Title, A. M.; Gillespie, B. A.; Mosher, J. W.

    1982-01-01

    A compact magnetograph system based on solid Fabry-Perot interferometers as the spectral isolation elements was studied. The theory of operation of several Fabry-Perot systems, the suitability of various magnetic lines, signal levels expected for different modes of operation, and the optimal detector systems were investigated. The requirements that the lack of a polarization modulator placed upon the electronic signal chain was emphasized. The PLZT modulator was chosen as a satisfactory component with both high reliability and elatively low voltage requirements. Thermal control, line centering and velocity offset problems were solved by a Fabry-Perot configuration.

  5. Mystery Powder Investigation

    NSDL National Science Digital Library

    Rachel HallettNjuguna

    2012-07-27

    Students will use their skills as scientists to identify a mystery white powder. This lesson is a hands-on, engaging way to build students' understanding of physical and chemical properties of several common compounds.

  6. Talcum Powder and Cancer

    MedlinePLUS

    ... and risk of endometrial cancer in postmenopausal women. Cancer Causes Control . 2012;23:1673?1680. Gertig DM, Hunter ... Use of talcum powder and endometrial cancer risk. Cancer Causes Control . 2012;2:513?519. Rosenblatt KA, Weiss ...

  7. Gelcasting superalloy powders

    SciTech Connect

    Janney, M.A.

    1995-12-31

    Gelcasting is a process for forming inorganic powders into complex shapes. It was originally developed for ceramic powders. A slurry of powder and a monomer solution is poured in to mold and polymerized in-situ to form gelled parts. Typically, only 2-4 wt % Polymer is used. The process has both aqueous and nonaqueous versions. Gelcasting is a generic process and has been used to produce ceramic parts from over a dozen different ceramic compositions ranging from alumina-based refractories to high-performance silicon nitride. Recently, gelcasting has been applied to forming superalloy powders into complex shapes. This application has posed several challenges not previously encountered in ceramics. In particular, problems were caused by the larger particle size and the higher density of the particles. Additional problems were encountered with binder removal. How these problems were overcome will be described.

  8. POWDER COAT APPLICATIONS

    EPA Science Inventory

    The report discusses an investigation of critical factors that affect the use of powder coatings on the environment, cost, quality, and production. The investigation involved a small business representative working with the National Defense Center for Environmental Excellence (ND...

  9. Hepagene (PowderJect).

    PubMed

    Jones, Taff

    2002-07-01

    Celltech Group (formerly Medeva) developed Hepagene, a recombinant polyvalent vaccine with potential activity against hepatitis B virus infections [353474]. In September 2000, PowderJect acquired the product as part of its acquisition of Celltech's vaccine manufacturing business [381557]. In July 2001, PowderJect reported that evaluation was nearing completion. At this time, the company expected to launch the vaccine in the coming months [443490]. Hepagene is a polyvalent vaccine with S, pre-S1 and pre-S2 hepatitis B epitopes forming the basis of its antigenicity. Additionally, these surface markers have been glycosylated in order to resemble the live virus more closely [254780]. By June 2000, Celltech and PowderJect were evaluating Hepagene, utilizing PowderJect's needle-less injection technology [379536]. In December 1999, Lehman Brothers predicted that the product had a 50% chance of reaching the treatment (rather than prevention) market, with potential peak sales of US $600 million [352078]. PMID:12186276

  10. Process of high temperature synthesis in producing composite carbide powders for thermally sprayed coatings

    NASA Astrophysics Data System (ADS)

    Szyma?ski, K.; Formanek, B.

    2011-05-01

    The paper presents the characterization of powders containing hard phases of chromium carbides in a NiCr matrix, intended for thermal spraying coatings. The synthesized composite powder containing hard phases and plastic matrix, produced in high-temperature synthesis with chosen powder metallurgy processes has been presented. Commercial materials, such as NiCr- CrxCy, are fabricated by means of agglomeration and sintering method. Processes of high temperature synthesis of Cr3C2, Cr7C3, Cr23C6 carbides combined with NiCr powder mechanical alloying are presented in the article. Parameters of the carbides synthesis were determined in the reactive -protective atmosphere. In the rotation- vibration mill, processes were conducted using grinding and appropriate mechanical alloying at variable amplitude. The standard and synthesized powders were thermally sprayed by HVOF method in Jet Kote II and Diamond Jet system. The structure and phase composition of the powders and coatings were determined by: light and scanning microscopy, X-ray phase analysis (RTG) and energy dispersive X-ray analysis (EDX). The structure and wear properties of HVOF sprayed coatings containing chromium carbides has been presented. The thermally sprayed coatings are characterized of wear resistance in abrasion and erosion tests. The sprayed coatings characterized high resistance in wear conditions.

  11. Influence of binders on infrared laser ablation of powdered tungsten carbide pressed pellets in comparison with sintered tungsten carbide hardmetals studied by inductively coupled plasma atomic emission spectrometry

    Microsoft Academic Search

    Markéta Holá; Vítezslav Otruba; Viktor Kanický

    2006-01-01

    Laser ablation (LA) was studied as a sample introduction technique for the analysis of powdered and sintered tungsten carbides (WC\\/Co) by inductively coupled plasma optical emission spectrometry (ICP–OES). The possibility to work with powdered and compact materials with close chemical composition provided the opportunity to compare LA sampling of similar substances in different forms that require different preparation procedures. Powdered

  12. Sol-gel synthesis and densification of aluminoborosilicate powders. Part 1: Synthesis

    NASA Technical Reports Server (NTRS)

    Bull, Jeffrey; Selvaduray, Guna; Leiser, Daniel

    1992-01-01

    Aluminoborosilicate powders high in alumina content were synthesized by the sol-gel process utilizing various methods of preparation. Properties and microstructural effects related to these syntheses were examined. After heating to 600 C for 2 h in flowing air, the powders were amorphous with the metal oxides comprising 87 percent of the weight and uncombusted organics the remainder. DTA of dried powders revealed a T(sub g) at approximately 835 C and an exotherm near 900 C due to crystallization. Powders derived from aluminum secbutoxide consisted of particles with a mean diameter 5 microns less than those from aluminum isopropoxide. Powders synthesized with aluminum isopropoxide produced agglomerates comprised of rod shaped particulates while powders made with the secbutoxide precursor produced irregular glassy shards. Compacts formed from these powders required different loadings for equivalent densities according to the method of synthesis.

  13. Process for synthesizing compounds from elemental powders and product

    DOEpatents

    Rabin, B.H.; Wright, R.N.

    1993-12-14

    A process for synthesizing intermetallic compounds from elemental powders is described. The elemental powders are initially combined in a ratio which approximates the stoichiometric composition of the intermetallic compound. The mixed powders are then formed into a compact which is heat treated at a controlled rate of heating such that an exothermic reaction between the elements is initiated. The heat treatment may be performed under controlled conditions ranging from a vacuum (pressureless sintering) to compression (hot pressing) to produce a desired densification of the intermetallic compound. In a preferred form of the invention, elemental powders of Fe and Al are combined to form aluminide compounds of Fe[sub 3] Al and FeAl. 25 figures.

  14. Shock-induced changes in HgO powder

    SciTech Connect

    Venturini, E.L.; Newcomer, P.P.; Morosin, B.; Holman, G.T.; Dunn, R.G.; Graham, R.A.

    1995-10-01

    Powder compacts of HgO were subjected to explosively-generated shock-wave loading in Sandia Bear fixtures and recovered for analysis. Although XRD powder spectra show only the orthorhombic form of HgO in both the as-received and recovered samples, XRD line profiles and TEM indicate up to an order of magnitude increase in crystallite size. Magnetic data reveal a superconducting transition below 4.2 K that is attributed to metallic {alpha}-Hg formed by a partial, shock-induced decomposition of the HgO, consistent with TEM identification of {alpha}-Hg particles using a cold stage. In addition, paramagnetic impurities present in the as-received HgO powder appear to be partially converted to a ferromagnetic or ferrimagnetic phase that dominates the magnetic properties of the recovered powder. The amounts of both the superconducting and ferromagnetic phases vary strongly with position within the shock recovery capsules.

  15. Thermal conductivity effects on steady state propagation speed during self-propagating high-temperature synthesis of Ti + C green compacts

    Microsoft Academic Search

    Z. Huque; G. M. S. Azad

    2008-01-01

    Thermal conductivities of mixtures of titanium (Ti) and graphite (C) powder compacts are experimentally investigated and the results are presented. These compacts are used in self-propagating high-temperature synthesis (SHS) of refractory, ceramic, and composite materials. Thermal conductivity values of these compacts are important for accurate modeling of the SHS process. Results show that, thermal conductivities of the compacts increase for

  16. Active wear and failure mechanisms of TiN-Coated high speed steel and tin-coated cemented carbide tools when machining powder metallurgically made stainless steels

    Microsoft Academic Search

    Laizhu Jiang; Hannu Hänninen; Jukka Paro; Veijo Kauppinen

    1996-01-01

    In this study, active wear and failure mechanisms of both TiN-coated high speed steel and TiN-coated cemented carbide tools\\u000a when machining stainless steels made by powder metallurgy in low and high cutting speed ranges, respectively, have been investigated.\\u000a Abrasive wear mechanisms, fatigue-induced failure, and adhesive and diffusion wear mechanisms mainly affected the tool life\\u000a of TiN-coated high speed steel tools

  17. Welding metallurgy of nickel alloys in gas turbine components

    SciTech Connect

    Lingenfelter, A. C., LLNL

    1997-05-21

    Materials for gas turbine engines are required to meet a wide range of temperature and stress application requirements. These alloys exhibit a combination of creep resistance, creep rupture strength, yield and tensile strength over a wide temperature range, resistance to environmental attack (including oxidation, nitridation, sulphidation and carburization), fatigue and thermal fatigue resistance, metallurgical stability and useful thermal expansion characteristics. These properties are exhibited by a series of solid-solution-strengthened and precipitation-hardened nickel, iron and cobalt alloys. The properties needed to meet the turbine engine requirements have been achieved by specific alloy additions, by heat treatment and by thermal mechanical processing. A thorough understanding of the metallurgy and metallurgical processing of these materials is imperative in order to successfully fusion weld them. This same basic understanding is required for repair of a component with the added dimension of the potential effects of thermal cycling and environmental exposure the component will have endured in service. This article will explore the potential problems in joining and repair welding these materials.

  18. Analysis of powder compaction process through equal channel angular extrusion

    E-print Network

    Kaushik, Anshul

    2009-05-15

    Page III IMPLEMENTATION OF MATERIAL MODELS IN FINITE ELEMENT SOFTWARE ABAQUS......................................................36 III.1 VUMAT for the Duva and Crow model ....................................37 III.2 Validation of the VUMAT.................................................................. 95 xviii LIST OF TABLES Page Table 1. Flow of data between ABAQUS and the VUMAT????????. 37 Table 2. Mechanical properties of the can materials???????????. 47 Table 3. Data from extrusions for extent of densification...

  19. Comparison of conventional and High Velocity Compaction of alumina powders.

    E-print Network

    Paris-Sud XI, Université de

    pressure: forming pressure, green density (homogeneity), pore size distribution of the tablets industrialization difficulties concerning explosive uses, for insufficient machine lifespan, for reliability to control the kinetic energy. CETIM is equipped with such a machine able to to reach punch velocities up

  20. Infrared Imaging of Pharmaceutical Materials Undergoing Compaction

    Microsoft Academic Search

    Simon R. Bechard; G. R. B. Down

    1992-01-01

    The goal of this study was to use infrared thermography as a new technique to investigate the heat released during compaction and consolidation of pharmaceutical powders and granules. Real-time temperature measurements without physical contact with tablets were provided by a highly sensitive (±0.1°C at 30°C) infrared camera (Agema Infrared Systems, Model 470 with CM-SOFT software). High-resolution images were captured at

  1. Iowa Powder Atomization Technologies

    SciTech Connect

    None

    2012-01-01

    The same atomization effect seen in a fuel injector is being applied to titanium metal resulting in fine titanium powders that are less than half the width of a human hair. Titanium melts above 3,000°F and is highly corrosive therefore requiring specialized containers. The liquid titanium is poured through an Ames Laboratory - USDOE patented tube which is intended to increase the energy efficiency of the atomization process, which has the ability to dramatically decrease the cost of fine titanium powders. This novel process could open markets for green manufacturing of titanium components from jet engines to biomedical implants.

  2. Powder towpreg process development

    NASA Technical Reports Server (NTRS)

    Baucom, Robert M.; Marchello, Joseph M.

    1991-01-01

    The process for dry powder impregnation of carbon fiber tows being developed at LaRC overcomes many of the difficulties associated with melt, solution, and slurry prepregging. In the process, fluidized powder is deposited on spread tow bundles and fused to the fibers by radiant heating. Impregnated tows have been produced for preform, weaving, and composite materials applications. Design and operating data correlations were developed for scale up of the process to commercial operation. Bench scale single tow experiments at tow speeds up to 50 cm/sec have demonstrated that the process can be controlled to produce weavable towpreg. Samples were woven and molded into preform material of good quality.

  3. Ti(C,N) cermets — Metallurgy and properties

    Microsoft Academic Search

    P. Ettmayer; H. Kolaska; W. Lengauer; K. Dreyer

    1995-01-01

    An overview of the metallurgical reactions during the vacuum sintering process of powder mixtures for the manufacture of cermets is presented. The relatively complex phase reactions in the multi-component system Ti\\/Mo\\/W\\/Ta\\/Nb\\/C,N-Co\\/Ni are discussed. The liquid binder phase reacts with titanium carbonitride by preferentially dissolving titanium carbide leaving titanium nitride undissolved. The compositions and the amounts of the gas species set

  4. Role of ceramic coating on electrical and magnetic properties of iron powder

    NASA Astrophysics Data System (ADS)

    Dhokey, N. B.; Pati, S.; Dhandare, S.; Bandal, V. S.

    2014-05-01

    Soft magnetic composite is a promising second generation magnetic material. It is widely used in both DC and AC applications. In the present work, magnesium compound coated iron powder (M-SMC) was used to fabricate the toroid cores of size Ø 30 × Ø 20 × 10 mm by powder metallurgy route. All these toroid cores were cured at different temperatures ranging from 600°C to 1000°C for 30 min in argon atmosphere controlled furnace. The electrical and magnetic properties of toroid cores were analyzed by Impedance Analyzer and B-H Analyzer respectively. M-SMC core cured at 800°C showed improved electrical properties for operating frequency up to 12000 kHz whereas magnetic properties were limited to applied magnetic field of 800 A/m.

  5. Formation of ceramic micro-channel by combination of laser beam machining and micro powder imprinting

    NASA Astrophysics Data System (ADS)

    Tsumori, Fujio; Hunt, Simon; Osada, Toshiko; Miura, Hideshi

    2015-06-01

    Microchannels made of polymers are commonly used for MEMS and micro-total analysis system (µTAS) devices. If a micro-channel structure can be constructed of a more stable material, the analysis of more reactant chemicals in harsher environments can be realized. In this research, we developed a process for fabricating a ceramic sheet with micro-channels. The developed process is based on powder metallurgy process. A compound material, a mixture of ceramic powder and polymer, was prepared as the sheet material. We employed laser machining to machine the sacrificial layer to form micro-channels inside the sheet. We also employed imprinting to form a structure with surface patterns and microchannels curving along with it. After the imprinted sheet was debound and sintered by heating, a ceramic sheet with micro-surface patterns and microchannels was obtained.

  6. Powder Cores s Molypermalloy

    E-print Network

    Software q Current Transformer Design Software q Inductor Design Software q Mag Amp Design Software POWDER.mag-inc.com PRODUCT LITERATURE AND DESIGN SOFTWARE CD CONTAINS q All Product Literature q Common Mode FIlter Design the Proper Core for Saturating Transformers q TWC-S3 Inverter Transformer Core Design and Material Selection

  7. Demystifying Mystery Powders.

    ERIC Educational Resources Information Center

    Kotar, Michael

    1989-01-01

    Describes science activities which use simple chemical tests to distinguish between materials and to determine some of their properties. Explains the water, iodine, heat, acid, baking soda, acid/base indicator, glucose, and sugar tests. Includes activities to enhance chemical testing and a list of suggested powders for use. (RT)

  8. High-strain-rate superplasticity at low temperature in a ZK61 magnesium alloy produced by powder metallurgy

    Microsoft Academic Search

    Hiroyuki Watanabe; Toshiji Mukai; Mamoru Mabuchi; Kenji Higashi

    1999-01-01

    In the present study, superplastic behavior of a pseudo single phase magnesium alloy, ZK61, was investigated at about half the absolute melting point. The material was produced by the P\\/M route, and had a fine grain size of [approximately]500 nm. It is demonstrated that the P\\/M ZK61 alloy can behave in a superplastic manner at a high strain rate of

  9. Effects of Thermocapillary Forces during Welding of 316L-Type Wrought, Cast and Powder Metallurgy Austenitic Stainless Steels

    Microsoft Academic Search

    Stefano Sgobba; T Daniellou

    2002-01-01

    The Large Hadron Collider (LHC) is now under construction at the European Organization for Nuclear Research (CERN). This 27 km long accelerator requires 1248 superconducting dipole magnets operating at 1.9 K. The cold mass of the dipole magnets is closed by a shrinking cylinder with two longitudinal welds and two end covers at both extremities of the cylinder. The end

  10. Processing map for controlling microstructure in hot working of hot isostatically pressed powder metallurgy NIMONIC AP1 superalloy

    Microsoft Academic Search

    M. C. Somani; E. S. Bhagiradha Rao; N. C. Birla; M. L. Bhatia; Vakil Singh; Y. V. R. K. Prasad

    1992-01-01

    The hot deformation behavior of hot isostatically pressed (HIP) NIMONIC AP-1 superalloy is characterized using processing\\u000a maps in the temperature range 950 ?C to 1200 ?C and strain rate range 0.001 to 100 s•1. The dynamic materials model has been used for developing the pro-cessing maps which show the variation of the efficiency\\u000a of power dissipation given by [2m\\/ (m

  11. Processing map for controlling microstructure in hot working of hot isostatically pressed powder metallurgy NIMONIC AP-1 superalloy

    NASA Astrophysics Data System (ADS)

    Somani, M. C.; Rao, E. S. Bhagiradha; Birla, N. C.; Bhatia, M. L.; Singh, Vakil; Prasad, Y. V. R. K.

    1992-10-01

    The hot deformation behavior of hot isostatically pressed (HIP) NIMONIC AP-1 superalloy is characterized using processing maps in the temperature range 950 °C to 1200 °C and strain rate range 0.001 to 100 s•1. The dynamic materials model has been used for developing the pro-cessing maps which show the variation of the efficiency of power dissipation given by [2m / ( m + 1)] with temperature and strain rate, with m being the strain rate sensitivity of flow stress. The processing map revealed a domain of dynamic recrystallization with a peak efficiency of 40 pct at 1125 °C and 0.3 s•1, and these are the optimum parameters for hot working. The microstructure developed under these conditions is free from prior particle boundary (PPB) de-fects, cracks, or localized shear bands. At 100 s•1 and 1200 °C, the material exhibits inter-crystalline cracking, while at 0.001 s•1, the material shows wedge cracks at 1200 °C and PPB cracking at 1000 °C. Also at strain rates higher than 10 s•1, adiabatic shear bands occur; the limiting conditions for this flow instability are accurately predicted by a continuum criterion based on the principles of irreversible thermodynamics of large plastic flow.

  12. Compact Reactor

    SciTech Connect

    Williams, Pharis E. [Williams Research, P.O. Box 554, Los Alamos, NM87544 (United States)

    2007-01-30

    Weyl's Gauge Principle of 1929 has been used to establish Weyl's Quantum Principle (WQP) that requires that the Weyl scale factor should be unity. It has been shown that the WQP requires the following: quantum mechanics must be used to determine system states; the electrostatic potential must be non-singular and quantified; interactions between particles with different electric charges (i.e. electron and proton) do not obey Newton's Third Law at sub-nuclear separations, and nuclear particles may be much different than expected using the standard model. The above WQP requirements lead to a potential fusion reactor wherein deuterium nuclei are preferentially fused into helium nuclei. Because the deuterium nuclei are preferentially fused into helium nuclei at temperatures and energies lower than specified by the standard model there is no harmful radiation as a byproduct of this fusion process. Therefore, a reactor using this reaction does not need any shielding to contain such radiation. The energy released from each reaction and the absence of shielding makes the deuterium-plus-deuterium-to-helium (DDH) reactor very compact when compared to other reactors, both fission and fusion types. Moreover, the potential energy output per reactor weight and the absence of harmful radiation makes the DDH reactor an ideal candidate for space power. The logic is summarized by which the WQP requires the above conditions that make the prediction of DDH possible. The details of the DDH reaction will be presented along with the specifics of why the DDH reactor may be made to cause two deuterium nuclei to preferentially fuse to a helium nucleus. The presentation will also indicate the calculations needed to predict the reactor temperature as a function of fuel loading, reactor size, and desired output and will include the progress achieved to date.

  13. JOURNAL DE PHYSIQUE Colloque C2, supplment au no6, Tome 39, Juin 1978,page C2-101 LES APPORTS DE LA METALLURGIE PHYSIQUE EN GOLOGIE

    E-print Network

    Paris-Sud XI, Université de

    LA METALLURGIE PHYSIQUE EN G�OLOGIE J.-C. DOUKHAN et J. PAQUET Laboratoire de structure et propriétés. The concepts of physical metallurgy are thus necessary to extra- polate the rheological laws obtained

  14. Elemental Powder Approaches to Ni3Al-Matrix Composites

    NASA Astrophysics Data System (ADS)

    Bose, A.; Moore, B.; German, R. M.; Stoloff, N. S.

    1988-09-01

    Reactive sintering and hot isostatic compaction of mixed elemental powders have been combined to fabricate full density NiAl intermetallic-matrix composites. This process involves the formation of the matrix compound from its elemental constituents through an exothermic reaction. Dispersed ceramic phases inhibit direct consolidation, necessitating superposition of external pressure via hot isostatic compaction to obtain full density. The latter process is termed reactive hot isostatic pressing (RHIP). Because of its flexibility and low cost, this fabrication process merits attention as a means of preparing monolithic compounds and intermetallic-matrix composites.

  15. Study on effects of powder and flake chemistry and morphology on the properties of Al-Cu-Mg-X-X-X powder metallurgy advanced aluminum alloys

    NASA Technical Reports Server (NTRS)

    Meschter, P. J.; Lederich, R. J.; Oneal, J. E.

    1986-01-01

    A study was conducted: (1) to develop rapid solidification processed (RSP) dispersoid-containing Al-3Cu-2Li-1Mg-0.2Zr alloys as substitutes for titanium alloys and commercial 2XXX aluminum alloys for service to at least 150 C; and (2) to develop RSP Al-4Li-Cu-Mg-Zr alloys as substitutes for high-strength commercial 7XXX alloys in ambient-temperature applications. RSP Al-3Cu-2Li-1Mg-0.2Zr alloys have density-normalized yield stresses at 150 C up to 52% larger than that of 2124-T851 and up to 30% larger than that of Ti-6Al-4V. Strength at 150 C in these alloys is provided by thermally stable delta' (Al3Li), T1 (Al2LiCu), and S' (Al2CuMg) precipitates. Density-normalized yield stresses of RSP Al-3Cu-2Li-1Mg-0.2Zr alloys are up to 100% larger than that of 2124-T851 and equivalent to that of Al-8Fe-4Ce at 260 C. Strength in the RSP alloys at 260 C is provided by incoherent dispersoids and subboundary constituent particles such as T1 and S. The RSP alloys are attractive substitutes in less than or = 100-h exposures for 2xxx and Al-4Fe-Ce alloys up to 260 C and for titanium alloys up to 150 C. RSP Al-4Li-Cu-Mg-Zr alloys have ambient-temperature yield and ultimate tensile stresses similar to that of 7050-T7651, and are 14% less dense. RSP Al-4Li-0.5Cu-1.5Mg-0.2Zr has a 20% higher specific yield stress, 40% higher specific elastic modulus, and superior corrosion resistance compared to the properties of 7050-T7651. Strength in the Al-4Li-Cu-Mg-Zr alloy class is primarily provided by the substructure and delta' precipitates and is independent of Cu:Mg ratio. Improvements in fracture toughness and transverse-orientation properties in both alloy classes depend on improved melt practices to eliminate oxide inclusions which are incorporated into the consolidated forms.

  16. Powder characteristics and coating conditions of fresh and reused polyester resins for electrostatic powder coating: powder recycling and loss prevention

    Microsoft Academic Search

    A. W. Lothongkum; R. Nonthapone; K. Seangkiatiyuth; W. Tanthapanichkoon

    2007-01-01

    Powder characteristics and coating conditions are significant factors in electrostatic powder coating. In this work, powder characteristics of the reused polyester resin or recycled powder particles in terms of shape, size, particle size distribution, moisture content, density, flowability, fluidity and chargeability were compared with those of fresh resin or as-received powder to consider powder recycling. The coating conditions for a

  17. Synthesis and processing of nanocrystalline powders for IR transparent windows

    NASA Astrophysics Data System (ADS)

    Jain, Mohit; Skandan, Ganesh; Singhal, Amit; Agrawal, Dinesh; Feng, Yi; La Monica, Joseph; Kirsch, J.

    2005-05-01

    Polycrystalline infrared transparent materials with good optical and mechanical properties are needed for the fabrication of infrared windows and domes. We have developed a synthesis process to produce MgO nanopowders. The average aggregate size of powder is in the range of 150 - 160 nm, with a narrow aggregate size distribution. Additionally, a protocol for compaction of nanocrystalline powders to achieve high green density (>50% of theoretical density) and microstructural uniformity has been described, as these factors are critical to sinter compacts to theoretical density with minimum number of flaws. Some of the samples were hot pressed and subsequently hot isostatically pressed (HIPed) for complete densification. Processing parameters are discussed to achieve uniformly dense sample with high degree of translucency. Some of the fully densified samples had a grain size as low as 100 - 300 nm.

  18. Processing polymeric powders

    NASA Technical Reports Server (NTRS)

    Throne, James L.

    1989-01-01

    The concept of uniformly and continuously depositing and sinter-fusing nominal 0.1 to 40 microns dimensioned electrostatically charged polymer powder particles onto essentially uniformly spread 5 to 20 micron grounded continuous fiber tow to produce a respoolable thermoplastic composite two-preg was formulated at NASA Langley. The process was reduced to practice under a NASA grant at the University of Akron this spring. The production of tow-preg is called phase 1. The production of ultrafine polymer powders from 5 to 10 percent (wt) polymer solids in solvent is considered. This is phase 0 and is discussed. The production of unitape from multi tow-pregs was also considered. This is phase 2 and is also discussed. And another approach to phase 1, also proposed last summer, was scoped. This is phase 1A and is also discussed.

  19. Fluidised powder as a new target technology

    E-print Network

    McDonald, Kirk

    : scope for a rig #12;Powder jet test plant layout Compressed air supplyVacuum/air powder #12;Powder jet/w solid to air ratio is not good enough!) · How does a dense, dense powder jet behave like? Preliminary tests at Gericke ltd #12;AIR/PRESSURE IN POWDER IN JET GENERATION AIR EXTRACTION POWDER OUT DENSE

  20. On effective compactness and sigma-compactness

    E-print Network

    Kanovei, Vladimir

    2011-01-01

    Using the Gandy -- Harrington topology and other methods of effective descriptive set theory, we prove several theorems on compact and sigma-compact pointsets. In particular we show that any $\\Sigma^1_1$ set $A$ of the Baire space $N^N$ either is covered by a countable union of compact $\\Delta^1_1$ sets, or $A$ contains a subset closed in $N^N$ and homeomorphic to $N^N$ (and then $A$ is not covered by a sigma-compact set, of course).

  1. Characterizing and modeling organic binder burnout from green ceramic compacts

    SciTech Connect

    Ewsuk, K.G.; Cesarano, J. III; Cochran, R.J.; Blackwell, B.F.; Adkins, D.R.

    1995-09-01

    New characterization and computational techniques have been developed to evaluate and simulate binder burnout from pressed powder compacts. Using engineering data and a control volume finite element method (CVFEM) thermal model, a nominally one dimensional (1-D) furnace has been designed to test, refine, and validate computer models that simulate binder burnout assuming a 1-D thermal gradient across the ceramic body during heating. Experimentally, 1-D radial heat flow was achieved using a rod-shaped heater that directly heats the inside surface of a stack of ceramic annuli surrounded by thermal insulation. The computational modeling effort focused on producing a macroscopic model for binder burnout based on continuum approaches to heat and mass conservation for porous media. Two increasingly complex models have been developed that predict the temperature and mass of a porous powder compact as a function of time during binder burnout. The more complex model also predicts the pressure within a powder compact during binder burnout. Model predictions are in reasonably good agreement with experimental data on binder burnout from a 57--65% relative density pressed powder compact of a 94 wt% alumina body containing {approximately}3 wt% binder. In conjunction with the detailed experimental data from the prototype binder burnout furnace, the models have also proven useful for conducting parametric studies to elucidate critical i-material property data required to support model development.

  2. Structural evolution in mechanically alloyed Al-Fe powders

    NASA Astrophysics Data System (ADS)

    Mukhopadhyay, D. K.; Suryanarayana, C.; Froes, F. H. (Sam)

    1995-08-01

    The structural evolution in mechanically alloyed binary aluminum-iron powder mixtures containing 1, 4, 7.3, 10.7, and 25 at. pct Fe was investigated using X-ray diffraction (XRD) and electron microscopic techniques. The constitution (number and identity of phases present), microstructure (crystal size, particle size), and transformation behavior of the powders on annealing were studied. The solid solubility of Fe in Al has been extended up to at least 4.5 at. pct, which is close to that observed using rapid solidification (RS) (4.4 at. pct), compared with the equilibrium value of 0.025 at. pct Fe at room temperature. Nanometer-sized grains were observed in as-milled crystalline powders in all compositions. Increasing the ball-to-powder weight ratio (BPR) resulted in a faster rate of decrease of crystal size. A fully amorphous phase was obtained in the Al-25 at. pct Fe composition, and a mixed amorphous phase plus solid solution of Fe in Al was developed in the Al-10.7 at. pct Fe alloy, agreeing well with the predictions made using the semiempirical Miedema model. Heat treatment of the mechanically alloyed powders containing the supersaturated solid solution or the amorphous phase resulted in the formation of the Al3Fe intermetallic in all but the Al-25 at. pct Fe powders. In the Al-25 at. pct Fe powder, formation of nanocrystalline Al5Fe2 was observed directly by milling. Electron microscope studies of the shock-consolidated mechanically alloyed Al-10.7 and 25 at. pct Fe powders indicated that nanometer-sized grains were retained after compaction.

  3. Titanium Sheet Fabricated from Powder for Industrial Applications

    SciTech Connect

    Peter, William H [ORNL; Muth, Thomas R [ORNL; Chen, Wei [ORNL; Yamamoto, Yukinori [ORNL; Jolly, Brian C [ORNL; Stone, Nigel [CSIRO ICT Center, Australia; Cantin, G.M.D. [CSIRO ICT Center, Australia; Barnes, John [CSIRO ICT Center, Australia; Paliwal, Muktesh [Ametek, Inc.; Smith, Ryan [Ametek, Inc.; Capone, Joseph [Ametek, Inc.; Liby, Alan L [ORNL; Williams, James C [Ohio State University; Blue, Craig A [ORNL

    2012-01-01

    In collaboration with Ametek and Commonwealth Scientific and Industrial Research Organization (CSIRO), Oak Ridge National Laboratory has evaluated three different methods for converting titanium hydride-dehydride (HDH) powder into thin gauge titanium sheet from a roll compacted preform. Methodologies include sintering, followed by cold rolling and annealing; direct hot rolling of the roll-compacted sheet; and hot rolling of multiple layers of roll compacted sheet that are encapsulated in a steel can. All three methods have demonstrated fully consolidated sheet, and each process route has the ability to produce sheet that meets ASTM B265 specifications. However, not every method currently provides sheet that can be highly formed without tearing. The degree of sintering between powder particles, post processing density, and the particle to particle boundary layer where compositional variations may exist, have a significant effect on the ability to form the sheet into useful components. Uniaxial tensile test results, compositional analysis, bend testing, and biaxial testing of the titanium sheet produced from hydride-dehydride powder will be discussed. Multiple methods of fabrication and the resulting properties can then be assessed to determine the most economical means of making components for industrial applications.

  4. The Origins of Metallurgy: Distinguishing Stone from Metal Cut-marks on Bones from Archaeological Sites

    Microsoft Academic Search

    Haskel J. Greenfield

    1999-01-01

    This paper presents an analytical procedure for identifying and mapping the introduction and spread of metallurgy to regions based upon the relative frequency of metal versus stone tool slicing cut-marks in butchered animal bone assemblages. The author conducted experiments to establish the relationship between the edge characteristics of metal and stone tools that create slicing cut-marks and the marks they

  5. Conversion of the under bump metallurgy into intermetallics: the impact on flip chip reliability

    Microsoft Academic Search

    Frank Stepniak

    2001-01-01

    In high temperature applications, the conversion of the under bump metallurgy (UBM) into UBM-Sn intermetallics can ultimately limit the reliability of flip chip components. Here, an intermetallic growth model characterizing the rate of electrical failure to the rate of UBM consumption is developed which derives a relationship between field reliability and accelerated temperature tests. For a flip chip structure employing

  6. Intensive Pre-Incan Metallurgy Recorded by Lake Sediments from the Bolivian Andes

    Microsoft Academic Search

    Mark B. Abbott; Alexander P. Wolfe

    2003-01-01

    The history of pre-Columbian metallurgy in South America is incomplete be- cause looting of metal artifacts has been pervasive. Here, we reconstruct a millennium of metallurgical activity in southern Bolivia using the stratigraphy of metals associated with smelting (Pb, Sb, Bi, Ag, Sn) from lake sediments deposited near the major silver deposit of Cerro Rico de Potosi ´. Pronounced metal

  7. FORMALIZATION OF WASTE MANAGEMENT PROGRAMS IN SUPPORT OF THE CHEMISTRY AND METALLURGY RESEARCH FACILITY AUTHORIZATION BASIS

    Microsoft Academic Search

    Richard C. Stupka; Lisa P. Stringfield

    2000-01-01

    The Chemistry and Metallurgy Research (CMR) Facility conducts analytical operations that are vital to the Stockpile Stewardship Program at Los Alamos National Laboratory (LANL). From 1952 to the early 1990s, this facility operated without a Safety Analysis Report (SAR) and bounded the risks associated with its diverse operations. An Interim Safety Analysis Report (ISAR) prepared in 1992, served until further

  8. University of Cambridge, Materials Science & Metallurgy H. K. D. H. Bhadeshia Other Techniques

    E-print Network

    Cambridge, University of

    University of Cambridge, Materials Science & Metallurgy H. K. D. H. Bhadeshia Other Techniques in a variety of imposed environments to yield information on the reduction of metal ores. In organic chemistry the technique has been widely used to study the degradation of polymers and to investigate the pyrolysis

  9. C12 PART IIA and Part IIB C12 MATERIALS SCIENCE AND METALLURGY

    E-print Network

    Colton, Jonathan S.

    criteria (Taylor and Quinney). Yield criteria applicable to metals, polymers and geological materialsC12 PART IIA and Part IIB C12 MATERIALS SCIENCE AND METALLURGY Course C12: Plasticity in metals and ceramics. Continuum plasticity (2 lectures) Stress-strain curves of real materials. Definition

  10. LASER WELDING -Literature Review Materials Science and Metallurgy Department, University of Cambridge, England. July 2002.

    E-print Network

    Cambridge, University of

    LASER WELDING - Literature Review C.A. Walsh Materials Science and Metallurgy Department carried and documented in a separate file. 1. Introduction Lasers are now being used in the automotive are used extensively for attaching auto-body panels to sub- assemblies. The advantages of laser welding

  11. Preparation and sintering behaviour of submicronic Bi4Ti3O12 powders

    Microsoft Academic Search

    M. Villegas; C. Moure; J. F. Fernandez; P. Duran

    1996-01-01

    Submicronic powders of Bi4Ti3O12 with different morphologies were prepared by both the oxalate coprecipitation and the conventional mixing oxides methods. Compacts of the two calcined powders were sintered at 850–1100 °C in air, and the densification process was studied by non-isothermal and dilatometric experiments. A rapid densification (> 97% theoretical density) below 875 °C took place in the Bi4Ti3O12 oxalate

  12. Synthesis of high purity carbide powders. (Latest citations from Engineered Materials abstracts). Published Search

    SciTech Connect

    Not Available

    1994-08-01

    The bibliography contains citations concerning the synthesis and preparation of high purity carbide powders. Articles discuss techniques of powder manufacture such as chemical vapor deposition, plasma arc reactions, sintering, hot pressing, combustion synthesis, precipitation, chemical reaction, self-propagating high temperature synthesis, shock or explosive compaction, and aerosol formation. Citations concern silicon carbides, titanium carbides, and other carbide materials and composites. (Contains 250 citations and includes a subject term index and title list.)

  13. Hydrothermal metallurgy for recycling of slag and glass

    NASA Astrophysics Data System (ADS)

    Tanaka, Toshihiro; Yoshikawa, Takeshi; Hirai, Nobumitsu; Katsuyama, Shigeru

    2009-05-01

    The authors have applied hydrothermal reactions to develop recycling processing of slag or glass. As an example, under hydrothermal conditions such as 200 300°C and 30 40MPa with H2O, powders made of glass can be sintered to become solidified glass materials containing about 10mass% H2O. When the glass containing H2O is heated again under normal pressure, the glass expands releasing H2O to make porous microstructure. H2O starts to emit just above the glass transition temperature. Therefore, when we have a glass with low glass transition temperature, we can make low temperature foaming glass. The SiO2-Na2O-B2O3 glass is a candidate to be such a foaming glass. In this paper, we describe our recent trial on the fabrication of the low temperature foaming glass by using hydrothermal reaction.

  14. TiC by SHS and dynamic compaction

    NASA Astrophysics Data System (ADS)

    Carton, Erik; Stuivinga, Marianne; Boluijt, Arien

    2001-06-01

    The explosive compaction of ceramic powder to high densities is hindered by the brittle fracture behavior of these materials. At room temperature ceramics lack in ductility, which causes fracturing of the compact during dynamic compaction (DC). Above the ductile-brittle transition temperature (DBTT) materials show a more ductile behavior. Therefore the explosive compaction of TiC was tried directly after its self-sustained high-temperature synthesis (SHS), at a temperature above the DBTT (circa 1700 K for TiC). Here, the indirect cylindrical explosive compaction configuration was used, since the gab between the flyer-tube and the tube containing the TiC (synthesis product) can serve as a thermal protection layer for the explosive layer that surrounds the flyer tube. The starting material, an equiatomic Ti/C powder mixture, showed only a 7 mm/s velocity of the axially moving combustion front through the SHS-tube. Therefore, it takes about 14 seconds to fully convert the Ti/C powder mixture to TiC in the 10 cm long SHS-tube used in the experiments. For a higher and more homogeneously distributed temperature within the TiC reaction product, a higher velocity of the SHS-front is required. In order to increase the velocity of the front, the starting powder mixture was pretreated by ball-milling. In this way the velocity of the SHS-front was increased up to 22 mm/s. By analysis of the broadening of the x-ray diffraction lines, the amount of micro-strain as well as the reduction in crystallite size (x-ray diffracting particle size) that resulted from the ball-milling treatment were determined. Furthermore, results of the combined SHS/DC experiments using ball-milled powders will be presented here.

  15. 40 CFR 471.02 - General definitions.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...specified temperature and duration to change the physical properties of the metal. (t) “Hot pressing” is forming a powder metallurgy compact at a temperature high enough to effect concurrent sintering. (u) “Hydrotesting” is the testing of piping...

  16. Counterintuitive compaction behavior of clopidogrel bisulfate polymorphs.

    PubMed

    Khomane, Kailas S; More, Parth K; Bansal, Arvind K

    2012-07-01

    Being a density violator, clopidogrel bisulfate (CLP) polymorphic system (forms I and II) allows us to study individually the impact of molecular packing (true density) and thermodynamic properties such as heat of fusion on the compaction behavior. These two polymorphs of CLP were investigated for in-die and out-of-die compaction behavior using CTC profile, Heckel, and Walker equations. Compaction studies were performed on a fully instrumented rotary tabletting machine. Detailed examinations of the molecular packing of each form revealed that arrangement of the sulfate anion differs significantly in both crystal forms, thus conferring different compaction behavior to two forms. Close cluster packing of molecules in form I offers a rigid structure, which has poor compressibility and hence resists deformation under compaction pressure. This results into lower densification, higher yield strength, and mean yield pressure, as compared with form II at a given pressure. However, by virtue of higher bonding strength, form I showed superior tabletability, despite its poor compressibility and deformation behavior. Form I, having higher true density and lower heat of fusion showed higher bonding strength. Hence, true density and not heat of fusion can be considered predictor of bonding strength of the pharmaceutical powders. PMID:22488254

  17. Comminution of stainless steel powders

    Microsoft Academic Search

    B. A. Borok; R. P. Schchegoleva; L. S. Golubeva; F. S. Sariadi; E. M. Rabinovich

    1974-01-01

    1.Atmospheric milling in barrel type mixers at a powder-to-ball weight ratio of 1::2 is an effective means of comminuting stainless steel powders produced by the coreduction process. In the work described, milling for 27 h was found to increase the amount of the -0.063-mm fraction from ~15 to ~75% for a Kh18N15 steel powder and from ~24.6 to ~70%for a

  18. Differential compaction behaviour of roller compacted granules of clopidogrel bisulphate polymorphs.

    PubMed

    Khomane, Kailas S; Bansal, Arvind K

    2014-09-10

    In the present work, in-die and out-of-die compaction behaviour of dry-granulated powders of clopidogrel bisulphate (CLP) polymorphs, form I and form II, was investigated using a fully instrumented rotary tablet press. Each polymorph was compacted at three different roller pressures [70.3 (S1), 105.5 (S2) and 140.6 (S3)kgf/cm(2)], and obtained granules were characterized for their physico-mechanical properties. Compaction data were analyzed for out-of-die compressibility, tabletability and compactibility profiles, and in-die Heckel, Kawakita and Walker analysis. The roller compacted granules of both forms showed markedly different tabletting behaviour. Roller pressure exhibited a trend on compaction behaviour of form I granules, whereas, in case of form II, the effect was insignificant. Tabletability of the six granule batches follows the order; I_S1>I_S2>I_S3>II_S1?II_S2?II_S3. In case of form I, the reduced tabletability of the granules compacted at higher roller pressure was attributed to the decreased compressibility and plastic deformation. This was confirmed by compressibility plot and various mathematical parameters derived from Heckel (Py), Kawakita (1/b) and Walker (W) equations. The reduced tabletability of form I granules was due to 'granule hardening' during roller compaction. On the other hand, insignificant effect of roller compaction on tabletting behaviour of form II granules was attributed to brittle fragmentation. The extensive fragmentation of granules offered new 'clean' surfaces and higher contact points that negated the effect of granule hardening. PMID:24971694

  19. Synthesis method for ultrananocrystalline diamond in powder employing a coaxial arc plasma gun

    NASA Astrophysics Data System (ADS)

    Naragino, Hiroshi; Tominaga, Aki; Hanada, Kenji; Yoshitake, Tsuyoshi

    2015-07-01

    A new method that enables us to synthesize ultrananocrystalline diamond (UNCD) in powder is proposed. Highly energetic carbon species ejected from a graphite cathode of a coaxial arc plasma gun were provided on a quartz plate at a high density by repeated arc discharge in a compact vacuum chamber, and resultant films automatically peeled from the plate were aggregated and powdered. The grain size was easily controlled from 2.4 to 15.0 nm by changing the arc discharge energy. It was experimentally demonstrated that the proposed method is a new and promising method that enables us to synthesize UNCD in powder easily and controllably.

  20. Preliminary attempt at sintering an ultrafine alumina powder using microwaves. Master's thesis

    SciTech Connect

    Alhambra, E.M.

    1994-09-01

    A commercially available microwave oven was used to sinter ultrafine alumina powders (0.02 - 0.05 micrometers particle size) with and without CaO sintering aid. The oven was modified by inserting a thermocouple probe through the bottom housing, and thoroughly insulating the interior with insulating material. The oven was placed in a glove box and filled with argon to prevent degradation of the thermocouple, and oxidation of the powdered graphite susceptor. Heating rates of 50-75 Deg C/sec with a maximum temperature of 1575 Deg C were obtained. Limited success in sintering of the the powder compacts was achieved in this preliminary effort. The microstructures of the sintered products were examined by scanning electron microscopy. It was concluded that further work is necessary to develop this technique into one which can be used for the routine sintering of fine powdered ceramic material. A review of the literature on microwave sintering of ceramic powders is also reported.

  1. Gas-Phase Combustion Synthesis of Aluminum Nitride Powder

    NASA Technical Reports Server (NTRS)

    Axelbaum, R. L.; Lottes, C. R.; Huertas, J. I.; Rosen, L. J.

    1996-01-01

    Due to its combined properties of high electrical resistivity and high thermal conductivity aluminum nitride (AlN) is a highly desirable material for electronics applications. Methods are being sought for synthesis of unagglomerated, nanometer-sized powders of this material, prepared in such a way that they can be consolidated into solid compacts having minimal oxygen content. A procedure for synthesizing these powders through gas-phase combustion is described. This novel approach involves reacting AlCl3, NH3, and Na vapors. Equilibrium thermodynamic calculations show that 100% yields can be obtained for these reactants with the products being AlN, NaCl, and H2. The NaCl by-product is used to coat the AlN particles in situ. The coating allows for control of AlN agglomeration and protects the powders from hydrolysis during post-flame handling. On the basis of thermodynamic and kinetic considerations, two different approaches were employed to produce the powder, in co-flow diffusion flame configurations. In the first approach, the three reactants were supplied in separate streams. In the second, the AlCl3 and NH3 were premixed with HCl and then reacted with Na vapor. X-ray diffraction (XRD) spectra of as-produced powders show only NaCl for the first case and NaCl and AlN for the second. After annealing at 775 C tinder dynamic vacuum, the salt was removed and XRD spectra of powders from both approaches show only AlN. Aluminum metal was also produced in the co-flow flame by reacting AlCl3 with Na. XRD spectra of as-produced powders show the products to be only NaCl and elemental aluminum.

  2. PVA aided microwave synthesis: A novel route for the production of nanocrystalline thoria powder

    NASA Astrophysics Data System (ADS)

    Chandramouli, V.; Anthonysamy, S.; Vasudeva Rao, P. R.; Divakar, R.; Sundararaman, D.

    1996-08-01

    A new method is reported for the preparation of nanocrystalline thoria powder that yields pellets of high density. The powder is prepared by denitration of an aqueous solution of thorium nitrate and polyvinyl alcohol (PVA) using microwave heating. The powder was characterized for its surface area and crystallite size by both X-ray line broadening and transmission electron microscopy. The reactivity of the powder was estimated by determining the density of the compacts prepared from these powders and sintered at 1573 K in air. For the sake of comparison, powders obtained by direct denitration were also characterized as above. The X-ray crystallite size for the calcined powders obtained by both routes is found to be ˜10 nm and found to be in agreement with the crystallite size obtained by conventional transmission electron microscopy. The density of pellets prepared from the powder produced by denitration in the presence of PVA was 92-93% of the theoretical density and that obtained with direct denitrated powder was ˜85% of theoretical density.

  3. Penetration of crystalline powder particles into excised human skin membranes and model gels from a supersonic powder injector.

    PubMed

    Lahm, Katja; Lee, Geoffrey

    2006-07-01

    The penetration of crystalline ibuprofen particles into excised human skin membranes and model target gels on actuation with the PowderJect ND1 ballistic needle-free injector has been examined. The deliverable dose of powder exiting the device is approximately 50% of the total cassette loading; the rest is lost via a gap forced open between the injector base and the surface of the target gel. It could be shown that substantial comminution of two different ibuprofen particle size fraction (38-53 microm, 53-75 microm) occurs within the injector on actuation. This resulted in an equiparation of the two initially different size fractions. Reduced comminution occurs with an ibuprofen/PVP (95:5) particulate formed by spray-drying/compaction/milling. On actuation into excised human skin membranes approximately 37% of cassette dose is recovered from the stratum corneum by stripping, and only 3% from the epidermis. It is concluded that powder delivery is mainly intra-epidermal with few particles fully breaching the stratum corneum. This is a consequence of the relative magnitude of the particle diameter (approximately 48 microm) and the stratum corneum thickness (approximately 10 microm). A 'soft' polyethylene glycol monolayer target gel gives the closest total percentage recovery of powder to that seen with the excised human skin membranes. Bilayer gels differentiated between surface impact/retention and penetration, but were difficult to handle. Powder penetration studies should therefore preferentially to be performed with human skin-membranes. PMID:16724324

  4. Nanoliposomal Dry Powder Formulations

    PubMed Central

    Patel, Gaurang; Chougule, Mahavir; Singh, Mandip; Misra, Ambikanandan

    2013-01-01

    Liposomal dry powder formulations (DPFs) have proven their superiority over conventional DPFs due to favorably improved pharmacokinetics and pharmacodynamics of entrapped drugs, and thus, reduced local and systemic toxicities. Nanoliposomal DPFs (NLDPFs) provide stable, high aerosolization efficiency to deep lung, prolonged drug release, slow systemic dilution, and avoid macrophage uptake of encapsulated drug by carrier-based delivery of nano-range liposomes. This chapter describes methods of preparation of nanoliposomes (NLs) and NLDPFs, using various techniques, and their characterization with respect to size distribution, flow behavior, in vitro drug release profile, lung deposition, cellular uptake and cytotoxicity, and in vivo pharmacokinetics and pharmacodynamics. Some examples have been detailed for better understanding of the methods of preparation and evaluation of NLDPFs by investigators. PMID:19903555

  5. Flow and compaction behaviour of ultrafine coated ibuprofen.

    PubMed

    More, Parth K; Khomane, Kailas S; Bansal, Arvind K

    2013-01-30

    Good flow and compaction properties are prerequisites for successful compaction process. Apart from initial profile, mechanical properties of pharmaceutical powders can get modified during unit processes like milling. Milled powders can exhibit a wide range of particle size distribution. Further downstream processing steps like compaction can be affected by this differential particle size distribution. This has greatest implications for formulations like high dose drugs wherein the active pharmaceutical ingredient (API) contributes the maximum bulk in the final formulation. The present study assesses the impact of dry coating with ultrafine particles of same material, on the flow and compaction properties of the core material. Ibuprofen was selected as model drug as it has been reported to have poor mechanical properties. Ultrafine ibuprofen (average size 1.75 ?m) was generated by Dyno(®) milling and was dry coated onto the core ibuprofen particles (average size 180 ?m). Compaction studies were performed using a fully instrumented rotary tablet press. Compaction data was analyzed for compressibility, tabletability, compactibility profiles and Heckel plot. Dry coating of the ibuprofen exhibited greater compressibility and tabletability, at lower compaction pressure. However, at compaction pressure above 220 MPa, compressibility and tabletability of coated as well as uncoated materials were found to be similar. Heckel analysis also supported the above findings, as P(y) value of uncoated ibuprofen was found to be 229.49 MPa and for 2.0% ultrafine coated ibuprofen was found to be 158.53 MPa. Lower P(y) value of ultrafine coated ibuprofen indicated ease of plastic deformation. Superior compressibility and deformation behaviour of ultrafine coated ibuprofen attributed to increased interparticulate bonding area. This strategy can also be explored for improving tabletability of high dose poorly compressible drugs. PMID:23142495

  6. Effect of repeated compaction of tablets on tablet properties and work of compaction using an instrumented laboratory tablet press.

    PubMed

    Gamlen, Michael John Desmond; Martini, Luigi G; Al Obaidy, Kais G

    2015-01-01

    The repeated compaction of Avicel PH101, dicalcium phosphate dihydrate (DCP) powder, 50:50 DCP/Avicel PH101 and Starch 1500 was studied using an instrumented laboratory tablet press which measures upper punch force, punch displacement and ejection force and operates using a V-shaped compression profile. The measurement of work compaction was demonstrated, and the test materials were ranked in order of compaction behaviour Avicel PH101?>?DCP/Avicel PH101?>?Starch?>?DCP. The behaviour of the DCP/Avicel PH101 mixture was distinctly non-linear compared with the pure components. Repeated compaction and precompression had no effect on the tensile fracture strength of Avicel PH101 tablets, although small effects on friability and disintegration time were seen. Repeated compaction and precompression reduced the tensile strength and the increased disintegration time of the DCP tablets, but improved the strength and friability of Starch 1500 tablets. Based on the data reported, routine laboratory measurement of tablet work of compaction may have potential as a critical quality attribute of a powder blend for compression. The instrumented press was suitable for student use with minimal supervisor input. PMID:24171692

  7. Three-dimensional simulations of nanopowder compaction processes by granular dynamics method

    NASA Astrophysics Data System (ADS)

    Boltachev, G. Sh.; Lukyashin, K. E.; Shitov, V. A.; Volkov, N. B.

    2013-07-01

    In order to describe and to study the processes of cold compaction within the discrete element method a three-dimensional model of nanosized powder is developed. The elastic forces of repulsion, the tangential forces of “friction” (Cattaneo-Mindlin), and the dispersion forces of attraction (van der Waals-Hamaker), as well as the formation and destruction of hard bonds between the individual particles are taken into account. The monosized powders with the size of particles in the range 10-40 nm are simulated. The simulation results are compared to the experimental data of the alumina nanopowders compaction. It is shown that the model allows us to reproduce experimental data reliably and, in particular, describes the size effect in the compaction processes. A number of different external loading conditions is used in order to perform the theoretical and experimental researches. The uniaxial compaction (the closed-die compaction), the biaxial (radial) compaction, and the isotropic compaction (the cold isostatic pressing) are studied. The real and computed results are in a good agreement with each other. They reveal a weak sensitivity of the oxide nanopowders to the loading condition (compaction geometry). The application of the continuum theory of the plastically hardening porous body, which is usually used for the description of powders, is discussed.

  8. Three-dimensional simulations of nanopowder compaction processes by granular dynamics method.

    PubMed

    Boltachev, G Sh; Lukyashin, K E; Shitov, V A; Volkov, N B

    2013-07-01

    In order to describe and to study the processes of cold compaction within the discrete element method a three-dimensional model of nanosized powder is developed. The elastic forces of repulsion, the tangential forces of "friction" (Cattaneo-Mindlin), and the dispersion forces of attraction (van der Waals-Hamaker), as well as the formation and destruction of hard bonds between the individual particles are taken into account. The monosized powders with the size of particles in the range 10-40 nm are simulated. The simulation results are compared to the experimental data of the alumina nanopowders compaction. It is shown that the model allows us to reproduce experimental data reliably and, in particular, describes the size effect in the compaction processes. A number of different external loading conditions is used in order to perform the theoretical and experimental researches. The uniaxial compaction (the closed-die compaction), the biaxial (radial) compaction, and the isotropic compaction (the cold isostatic pressing) are studied. The real and computed results are in a good agreement with each other. They reveal a weak sensitivity of the oxide nanopowders to the loading condition (compaction geometry). The application of the continuum theory of the plastically hardening porous body, which is usually used for the description of powders, is discussed. PMID:23944456

  9. [Risk and features of occupational diseases in nonferrous metallurgy workers of Kolsky Transpolar area].

    PubMed

    Siurin, S A; Chashchin, V P; Frolova, N M

    2015-01-01

    The study covered data on 977 cases of occupational diseases in 615 workers of nonferrous metallurgy in Kolsky Transpolar area. Findings are high risk of occupational diseases in workers engaged into electrolysis production of aluminium, all nickel reprocessing and pyrometallic copper reprocessing (GR 7.02-10.0). Electrolysis operators and anode operators of aluminium production are more prone to occupational diseases, with bone and muscular disorders (46.8%) prevalent in the morbidity structure. Respiratory diseases are more prevalent (68.2-100%) in the occupational morbidity structure of copper-nickelindustry workers. Conclusion is made on mandatory improvement of the work conditions and more effective individual protective means against occupational hazards in workers of nonferrous metallurgy in Kolsky Transpolar area. PMID:25895247

  10. 21 CFR 73.2647 - Copper powder.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...2012-04-01 2012-04-01 false Copper powder. 73.2647 Section 73...CERTIFICATION Cosmetics § 73.2647 Copper powder. (a) Identity and specifications. The color additive copper powder shall conform in identity...

  11. 21 CFR 73.2647 - Copper powder.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...2014-04-01 2014-04-01 false Copper powder. 73.2647 Section 73...CERTIFICATION Cosmetics § 73.2647 Copper powder. (a) Identity and specifications. The color additive copper powder shall conform in identity...

  12. 21 CFR 73.2647 - Copper powder.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...2010-04-01 2010-04-01 false Copper powder. 73.2647 Section 73...CERTIFICATION Cosmetics § 73.2647 Copper powder. (a) Identity and specifications. The color additive copper powder shall conform in identity...

  13. 21 CFR 73.2647 - Copper powder.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...2013-04-01 2013-04-01 false Copper powder. 73.2647 Section 73...CERTIFICATION Cosmetics § 73.2647 Copper powder. (a) Identity and specifications. The color additive copper powder shall conform in identity...

  14. 21 CFR 73.2647 - Copper powder.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...2011-04-01 2011-04-01 false Copper powder. 73.2647 Section 73...CERTIFICATION Cosmetics § 73.2647 Copper powder. (a) Identity and specifications. The color additive copper powder shall conform in identity...

  15. The Effects of Processing Parameters on Microstructure and Properties of Laser Deposited PM Alloy 690N{sub 2} Powder

    SciTech Connect

    J.W. Sears

    2002-04-05

    Powder Metallurgy (PM) Alloy 690N{sub 2}, the PM derivative of Inconel 690 (IN 690), has been shown to have a higher elevated temperature yield strength and superior stress corrosion cracking (SCC) resistance than conventionally processed IN 690. The property improvements seen in Alloy PM 690N{sub 2} are due to interstitial nitrogen strengthening and precipitation hardening resulting from the formation of fine Titanium/Chromium-nitrides. The application of Alloy PM 690N{sub 2} has had limited use due to the high costs involved in producing wrought products from powder. Laser Powder Deposition (LPD) offers another technique to take advantage of PM 690N{sub 2} properties. Three different variations of the Alloy 690 chemistry have been deposited, PM chemistry-nitrogen atomized (PM 690N{sub 2}), Ingot Metallurgy (IM) chemistry--nitrogen atomized (IM 690N{sub 2}), and IM chemistry--argon atomized (IM 690Ar). The microstructural and mechanical property variations of these LPD deposited materials are reported. Alloy PM 690N{sub 2} powder was laser deposited at rates from .1 to over 12 cubic inches per hour at laser input powers ranging from 250 to 5000 watts using both CO{sub 2} and Nd:YAG lasers. in all cases a fully dense material has been produced. There is a question however of how the properties of this material respond over such a wide range of parameters. An attempt has been made to correlate the processing conditions with the resultant microstructures and properties. The effects of LPD on the microstructural features and properties of Alloy PM 690N{sub 2} are discussed.

  16. Characterization of lead-free solders and under bump metallurgies for flip-chip package

    Microsoft Academic Search

    Jong-Kai Lin; Ananda De Silva; Darrel Frear; Yifan Guo; Jin-Wook Jang; Li Li; D. Mitchell; B. Yeung; C. Zhang

    2001-01-01

    A variety of Pb-free solders and under bump metallurgies (UBMs) was investigated for flip chip packaging applications. The result shows that the Sn-0.7Cu eutectic alloy has the best fatigue life and it possess the most desirable failure mechanism in both thermal and isothermal mechanical tests regardless of UBM type. Although the electroless Ni-P UBM has a much slower reaction rate

  17. Contrasting lead speciation in forest and tilled soils heavily polluted by lead metallurgy

    Microsoft Academic Search

    Vojt?ch Ettler; Aleš Van?k; Martin Mihaljevi?; Petr Bezdi?ka

    2005-01-01

    The concentration trends and chemical fractionation of Pb was studied in eight tilled and forest soil profiles heavily polluted by Pb metallurgy in the P?íbram district, Czech Republic. The highest Pb concentrations were observed in surface and subsurface horizons attaining 35300mgkg?1 in forest soils and 1233mgkg?1 in tilled soils. Total Pb concentrations were one order of magnitude lower in tilled

  18. Characterization of lead-free solders and under bump metallurgies for flip-chip package

    Microsoft Academic Search

    Jong-Kai Lin; Ananda De Silva; Darrel Frear; Yifan Guo; Scott Hayes; Jin-Wook Jang; Li Li; Dianne Mitchell; Betty Yeung; Charles Zhang

    2002-01-01

    A variety of Pb-free solders and under bump metallurgies (UBMs) was investigated for flip chip packaging applications. The result shows that the Sn-0.7Cu eutectic alloy has the best fatigue life and it possess the most desirable failure mechanism in both thermal and isothermal mechanical tests regardless of UBM type. Although the electroless Ni-P UBM has a much slower reaction rate

  19. The role of metallurgy in the NIST investigation of the World Trade Center towers collapse

    Microsoft Academic Search

    S. W. Banovic; T. Foecke; W. E. Luecke; J. D. McColskey; C. N. McCowan; T. A. Siewert; F. W. Gayle

    2007-01-01

    On August 21, 2002, on the direction of the U.S. Congress, the National Institute of Standards and Technology (NIST) initiated\\u000a an investigation into the collapse of the World Trade Center (WTC) towers. In support of the overall investigation goals,\\u000a the NIST Metallurgy and Materials Reliability Divisions pursued three objectives: assess the quality of the steel used in\\u000a the construction of

  20. Physical metallurgy of nickel-base alloys as it relates to corrosion

    Microsoft Academic Search

    R. M. Latanision

    1988-01-01

    In service environments ranging from high purity water to deep sour gas, the corrosion and embrittlement characteristics of\\u000a nickel-base alloys have been found to be intimately related to the physical metallurgy of the alloys. Intergranular corrosion,\\u000a stress corrosion cracking, corrosion fatigue, and hydrogen embrittlement have been associated with, for example, grain boundary\\u000a microstructure and microchemistry, solute segregation, ordering phenomena, and

  1. Environmental concerns in extractive metallurgy. (Latest citations from METADEX). Published Search

    SciTech Connect

    Not Available

    1994-09-01

    The bibliography contains citations concerning pollution control in the extractive metallurgical industry. Articles discuss disposal of waste solids resulting from ore processing, treatment of waste water, recovery of particulate fines, material recovery from waste water, and remediation of waste streams from extractive metallurgy. Citations address processing of copper, gold, zinc, uranium, iron, lead, and other metal materials and metal-bearing ores. (Contains a minimum of 152 citations and includes a subject term index and title list.)

  2. Synthesis of boron nitride powders

    NASA Astrophysics Data System (ADS)

    Dreissig, Dirk Horst

    2002-09-01

    In the materials science community there is much interest in the development of new, efficient approaches for preparing ceramic powders having properties or performance characteristics not found with powders produced by traditional metallurgical synthesis methods. In this regard, aerosol-based syntheses are finding general acceptance for the preparation of non-metal and metal oxide powders. In contrast, much less effort has been given to aerosol-type syntheses for non-oxide powders despite potentially useful benefits. This dissertation describes the application of two chemical systems in aerosol assisted vapor phase synthesis (AAVS) for the preparation of spherical morphology boron oxynitride, BNxOy, powders that are subsequently converted to spherical morphology boron nitride in a second nitridation step. Chapter 1 describes the AAVS synthesis of BNxOy powders using a reaction of an aqueous boric acid containing aerosol with ammonia at 1000°C. The effect of reactor tube material, total gas flow rate, ammonia concentration, boric acid concentration, and urea addition to the boric acid aerosol on the percent oxygen composition is described. The resulting BNxOy powders contain significant amounts of oxygen that require replacement in a second stage nitridation reaction at elevated temperature under ammonia. The influences of the reaction temperature profile, crucible geometry and transformation additive on final oxygen composition and powder crystallinity are described. Chapter 2 outlines the formation of BNxOy powders from an AAVS reaction between the boron precursor (MeO)3B and ammonia. The formation of the powders is studied as a function of total gas flow rate and ammonia concentration. In all cases the resulting powders contain lower levels of oxygen compared to powders produced from aqueous boric acid aerosols. The conversion of the BNxOy powders in the second stage nitridation reaction with ammonia is examined as a function of crucible geometry, temperature profile and ammonia flow rate. In support of this process, the molecular reaction between (MeO)3B and NH3 was reexamined. The adduct, (MeO)3B·NH3, was isolated and its molecular structure determined by single crystal X-ray diffraction techniques. The results of these studies provide guidance for more detailed studies that should result in industrial scale synthesis of spherical morphology BN which currently is not formed by standard metallurgical syntheses. This new material has potential applications in several areas including the formation of BN loaded organic polymer composites.

  3. Simulation of roller compaction with subsequent tableting and characterization of lactose and microcrystalline cellulose.

    PubMed

    Hein, Stephanie; Picker-Freyer, Katharina M; Langridge, John

    2008-01-01

    Tablets are by far the most common solid oral dosage forms, and many drugs need to be granulated before they can be tableted. Increasingly roller compaction is being used as a dry granulation technique; however it is a very time and material intensive method. Thus some mini roller compactors and simulations of the roller compaction process have been developed as a means of studying the technique at small scale. An important factor in the selection of materials for roller compaction is their ability to be recompressed into tablets after the initial roller compaction and milling steps. In this paper the roller compaction process was simulated on the basis of some models by Gereg and Cappola (2002) and Zinchuk et al. (2004). An eccentric tableting machine was used to make compacts from alpha-lactose monohydrate, anhydrous beta-lactose, spray-dried lactose and microcrystalline cellulose at different maximum relative densities (rho rel,max 0.6-0.9). These compacts were milled immediately to granules with a rotary granulator. The properties of the granules were analyzed and compared to the properties of the original powders. These granules and powders were then tableted at different maximum relative densities (rho rel,max 0.75-0.95) and their properties including elastic recovery, crushing force and 3D-model were analyzed. The properties of the tablets made from the granules were compared to the properties of the tablets made from the powders to determine which excipients are most suitable for the roller compaction process. The study showed that anhydrous beta-lactose is the preferred form of lactose for use in roller compaction since compaction did not affect tablet crushing force to a large extent. With the simulation of roller compaction process one is able to find qualified materials for use in roller compaction without the necessity of a great deal of material and time. PMID:18728996

  4. The effect of molybdenum on the physical and mechanical metallurgy of advanced titanium-aluminide alloys and metal matrix composites

    NASA Astrophysics Data System (ADS)

    Quast, Jeffrey Paul

    This dissertation represents a systematic study of microstructure-mechanical property relationships of titanium-aluminum-niobium-molybdenum (Ti-Al-Nb-Mo) alloys and metal matrix composites (MMCs). The aspects investigated were the microstructures, elevated-temperature creep behavior, room-temperature and elevated-temperature tensile behavior, and the out-of-phase thermomechanical fatigue behavior. The specific alloy compositions investigated were: Ti-24Al-17Nb-0.66Mo (at.%) and Ti-24Al-17Nb-2.3Mo (at.%). The MMCs were reinforced with Ultra SCS-6 fibers and the specific compositions of the matrices were: Ti-24Al-17Nb-0.66Mo (at.%), Ti-24Al-17Nb-1.1Mo (at.%), and Ti-24Al-17Nb-2.3Mo (at.%). All of the materials were fabricated using a powder-metallurgy, tape casting technique. A subtransus heat-treatment produced microstructures containing a hexagonal close-packed a2 phase, orthorhombic (O) phase, and a body-centered cubic (BCC) phase. The higher Mo contents were shown to stabilize the BCC phase and result in an increase the O+BCC phase volume percent and a subsequent decrease in the a2 phase volume percent. The creep deformation behavior of the alloys and MMCs was the main focus of this dissertation. Creep experimentation was performed to understand the deformation mechanisms as a function of stress, temperature, and strain rate. Higher Mo contents significantly increased the creep resistance of the alloys, which was attributed to the decrease in the number of a2/a2 grain boundaries, increased O+BCC colony size, and Mo solid solution strengthening. This was one of the major findings of the work. In-situ tensile-creep experiments indicated that grain boundaries were the locus of deformation and cracking in each of the alloys investigated. MMC creep experimentation was performed with the fibers aligned perpendicular to the loading direction. Similar to alloy creep results, higher Mo contents increased the creep resistance of the MMCs. However, the creep resistance of the MMCs was significantly less than that of their respective alloy compositions. An effort was made to model the creep behavior of the MMCs based on the creep behavior of the alloys and fiber/matrix bond strength. The model predicted the secondary creep rates of the MMCs well for a condition assuming no bond strength between the fiber and matrix. The model predicts that the MMC will exhibit a secondary creep rate lower than that for the alloy when the applied creep stress is less than the fiber/matrix bond strength. However, no such transition was observed in the experimental data. Experimental testing and finite element modeling revealed that the interfacial bond strength between the matrix and the fiber was indeed very small, suggesting that the MMC creep resistance would not be greater than the matrix alloy under practical loading applications. Overall, the work performed in this dissertation helped fill the knowledge gap which exists for the physical and mechanical metallurgy effects of varying Mo additions in titanium aluminides.

  5. A millennium of metallurgy recorded by lake sediments from Morococha, Peruvian Andes.

    PubMed

    Cooke, Colin A; Abbott, Mark B; Wolfe, Alexander P; Kittleson, John L

    2007-05-15

    To date, information concerning pre-Colonial metallurgy in South America has largely been limited to the archaeological record of artifacts. Here, we reconstruct a millennium of smelting activity in the Peruvian Andes using the lake-sediment stratigraphy of atmospherically derived metals (Pb, Zn, Cu, Ag, Sb, Bi, and Ti) and lead isotopic ratios (206Pb/ 207Pb) associated with smelting from the Morococha mining region in the central Peruvian Andes. The earliest evidence for metallurgy occurs ca. 1000 A.D., coinciding with the fall of the Wari Empire and decentralization of local populations. Smelting during this interval appears to have been aimed at copper and copper alloys, because of large increases in Zn and Cu relative to Pb. A subsequent switch to silver metallurgy under Inca control (ca. 1450 to conquest, 1533 A.D.) is indicated by increases in Pb, Sb, and Bi, a conclusion supported by further increases of these metals during Colonial mining, which targeted silver extraction. Rapid development of the central Andes during the 20th century raised metal burdens by an order of magnitude above previous levels. Our results represent the first evidence for pre-Colonial smelting in the central Peruvian Andes, and corroborate the sensitivity of lake sediments to pre-Colonial metallurgical activity suggested by earlier findings from Bolivia. PMID:17547165

  6. Apollo 12 Seismic Signal: Indication of a Deep Layer of Powder

    Microsoft Academic Search

    Thomas Gold; Steven Soter

    1970-01-01

    The seismic signal caused by the Apollo 12 lunar module is interpreted in terms of propagation between source and receiver through a layer of powder in which sound velocity increases with depth. This increase, which is due to compaction, extends over several kilometers and leads to a concentration of seismic waves toward the surface. Computer simulations with the use of

  7. Sintering characteristics of Fe and FeCo alloy ultrafine powders

    Microsoft Academic Search

    Y. Sakka; T. Uchikoshi; E. Ozawa

    1993-01-01

    Sintering characteristics of three kinds of iron and FeCo alloy ultrafine powders (UFPs) in vacuum and a hydrogen atmosphere were examined by continuously measuring their dimensions, and observing their structural changes. The UFPs exposed to air contain mixtures of oxide and hydroxide phases. The oxide phase increased during heating in vacuum. The compacts of the UFPs shrunk slightly at temperatures

  8. Compaction Behavior of Isomalt after Roll Compaction

    PubMed Central

    Quodbach, Julian; Mosig, Johanna; Kleinebudde, Peter

    2012-01-01

    The suitability of the new isomalt grade galenIQ™ 801 for dry granulation and following tableting is evaluated in this study. Isomalt alone, as well as a blend of equal parts with dibasic calcium phosphate, is roll compacted and tableted. Particle size distribution and flowability of the granules and friability and disintegration time of the tablets are determined. Tensile strength of tablets is related to the specific compaction force during roll compaction and the tableting force. In all cases, the tensile strength increases with raising tableting forces. The specific compaction force has a different influence. For isomalt alone the tensile strength is highest for tablets made from granules prepared at 2 kN/cm and 6 kN/cm and decreases at higher values, i.e., >10 kN/cm. Tensile strength of the blend tablets is almost one third lower compared to the strongest tablets of pure isomalt. Friability of pure isomalt tablets is above the limit. Disintegration time is longest when the tensile strength is at its maximum and decreases with higher porosity and lower tensile strengths. Isomalt proves to be suitable for tableting after roll compaction. Even though the capacity as a binder might not be as high as of other excipients, it is a further alternative for the formulation scientist. PMID:24300366

  9. Silica powders for powder evacuated thermal insulating panel and method

    DOEpatents

    Harris, M.T.; Basaran, O.A.; Kollie, T.G.; Weaver, F.J.

    1996-01-02

    A powder evacuated thermal insulating panel using generally spherical and porous silica particles of a median size less than about 100 nanometers in diameter, a pour packing density of about 0.4 to 0.6 g/cm{sup 3} and an external surface area in the range of about 90 to 600 m{sup 2}/g is described. The silica powders are prepared by reacting a tetraalkyl silicate with ammonia and water in an alcohol solvent, distilling the solution after the reaction to remove the ammonia and recover the alcohol. The resulting aqueous slurry was dried, ball-milled, and dried again to provide the silica particles with defined internal and external porosity. The nanometer size and the large external surface area of the silica particles along with the internal and external porosity of the silica particles provide powder evacuated thermal insulating panels with significantly higher R-values than obtainable using previously known silica powders. 2 figs.

  10. Method for molding ceramic powders

    DOEpatents

    Janney, M.A.

    1990-01-16

    A method for molding ceramic powders comprises forming a slurry mixture including ceramic powder, a dispersant for the metal-containing powder, and a monomer solution. The monomer solution includes at least one multifunctional monomer, a free-radical initiator, and an organic solvent. The slurry mixture is transferred to a mold, and the mold containing the slurry mixture is heated to polymerize and crosslink the monomer and form a firm polymer-solvent gel matrix. The solid product may be removed from the mold and heated to first remove the solvent and subsequently remove the polymer, where after the product may be sintered.

  11. Preparation and study on performance of submicron nickel powder for multilayer chip positive temperature coefficient resistance

    NASA Astrophysics Data System (ADS)

    Chen, Yong; Gong, Shu-Ping; Fu, Qiu-Yun; Zheng, Zhi-Ping; Huang, Ri-Ming; Su, Peng

    2010-11-01

    Base metal nickel is often used as the inner electrode in multilayer chip positive temperature coefficient resistance (PTCR). The fine grain of ceramic powders and base metal nickel are necessary. This paper uses reducing hydrazine to gain submicron nickel powder whose diameter was 200-300 nm through adjusting the consumption of nucleating agent PVP properly. The submicron nickel powder could disperse well and was fit for co—fired of multilayer chip PTCR. It analyes the submicron nickel powder through x-ray Diffraction (XRD) and calculates the diameter of nickel by PDF cards. Using XRD analyses it obtains several conclusions: If the molar ratio of hydrazine hydrate and nickel sulfate is kept to be a constant, when enlarging the molar ratio of NaOH/Ni2+, the diameter of nickel powder would become smaller. When the temperature in the experiment raises to 70-80 °C, nickel powder becomes smaller too. And if the molar ratio of NaOH/Ni2+ is 4, when molar ratio of (C2H5O)2/Ni2+ increases, the diameter of nickel would reduce. Results from viewing the powders by optical microscope should be the fact that the electrode made by submicron nickel powder has a better formation and compactness. Furthermore, the sheet resistance testing shows that the electrode made by submicron nickel is smaller than that made by micron nickel.

  12. *Correspondence to: Zbigniew Galias, Department of Electrical Engineering, University of Mining and Metallurgy, al. Mickiewicza 30, 30-059 KrakoH w, Poland.

    E-print Network

    Galias, Zbigniew

    and Metallurgy, al. Mickiewicza 30, 30-059 KrakoH w, Poland. Contract/grant sponsor: University of Mining and Metallurgy, KrakoH w Contract/grant number: 10.10.120.133 CCC 0098}9886/99/060589}16$17.50 Received September and Metallurgy, al. Mickiewicza 30, 30-059 KrakoH w, Poland SUMMARY In this paper we consider the problem

  13. Improving The Making Of Powder Of RE-Si Ferroalloy Using High-Speed Photographic Technology

    NASA Astrophysics Data System (ADS)

    Jia, Dayoung; Liu, Chunsheng

    1990-01-01

    Because of the increasing application of RE and the need for the injection metallurgy, we have been trying to find out a suitable powder-making technique of RE-Si ferroalloy widely used as additive in steel and spheroidal cast iron. In this paper, the high-speed photographic technology has been used to analyse the different atomizing methods of RE-Si ferroalloy, especially the atomizing method with gas-jetting and quenching method in water. During atomizing, not only has the process of breaking a single molten alloy droplet been photographed, but also the moving track and changing speed of different sizes of particles have been photographed, and then analysed and calculated. Here we have also put forward our opinion of the mechanism of the quenching process in water of RE-Si ferroalloy, providing a theoretical basis for reliable atomizing technique.

  14. Improved blend and tablet properties of fine pharmaceutical powders via dry particle coating.

    PubMed

    Huang, Zhonghui; Scicolone, James V; Han, Xi; Davé, Rajesh N

    2015-01-30

    The improvements in the flow and packing of fine pharmaceutical powder blends due to dry coating of micronized acetaminophen (mAPAP, ?11?m), a model poorly flowing drug, are quantified. Poor flow and packing density of fine excipients (?20?m) allowed testing the hypothesis that dry coating of cohesive API may counteract poor flow and packing of fine pharmaceutical powder blends. Further, fine excipients could improve compaction and reduce segregation tendency. It was found that flow function coefficient (FFC) and bulk density enhancements for 10%, 30%, and 60% (w/w), API loading blends with dry coated API are significantly higher than those without coated silica. At the highest API loading, for which coarser excipients were also used as reference, the flow and packing of dry coated mAPAP blends were significantly increased regardless of the excipient particle size, exceeding those of a well compacting excipient, Avicel 102. In addition, tensile strength of tablets with fine excipients was significantly higher, indicating improved compactibility. These results show for the first time that dry coating of fine, cohesive API powder leads to significantly improved flow and packing of high API loading blends consisting of fine excipients, while achieving improved tablet compactibility, suggesting suitability for direct compaction. PMID:25475016

  15. Ceramic powder for sintering materials

    NASA Technical Reports Server (NTRS)

    Akiya, H.; Saito, A.

    1984-01-01

    Surface activity of ceramic powders such as MgO and Al2O3, for use in sintering with sp. emphasis on their particle size, shape, particle size distribution, packing, and coexisting additives and impurities are reviewed.

  16. An Experimental Evaluation of the Gerdemann-Jablonski Compaction Equation

    NASA Astrophysics Data System (ADS)

    Machaka, Ronald; Chikwanda, Hilda K.

    2015-05-01

    This paper reports on an attempt to independently evaluate the validity and applicability of a new compaction equation recently presented by Gerdemann and Jablonski [ Metallurgical and Materials Transactions A, 42 (2011) 1325-1333] using experimental data. Furthermore, the rationality of Gerdemann and Jablonski's interpretation of the equation parameters is examined. The results are discussed in terms of the comparative evaluation of four different titanium powders (sponge Ti, CP TiH2, Grade 2 CP Ti, and TiH2-SS316L nanocomposite blend prepared by high energy milling) cold pressed in die to compaction pressures of up to 1300 MPa.

  17. Luminescence of powdered uranium glasses

    NASA Technical Reports Server (NTRS)

    Eubanks, A. G.; Mcgarrity, J. M.; Silverman, J.

    1974-01-01

    Measurement of cathodoluminescence and photoluminescence efficiencies in powdered borosilicate glasses having different particle size and different uranium content. Excitation with 100 to 350 keV electrons and with 253.7 nm light was found to produce identical absolute radiant exitance spectra in powdered samples. The most efficient glass was one containing 29.4 wt% B2O3, 58.8 wt% SiO2, 9.8 wt% Na2O and 2.0 wt% UO2.

  18. Compact homogeneous CR manifolds

    Microsoft Academic Search

    Dmitry V. Alekseevsky; Andrea F. Spiro

    2000-01-01

    We classify all compact simply connected homogeneous CR manifolds $M$ of codimension one and with non-degenerate Levi form up to CR equivalence. The classification is based on our previous results and on a description of the maximal connected compact group $G(M)$ of automorphisms of $M$. We characterize also the standard homogeneous CR manifolds as the homogeneous CR manifolds whose group

  19. Compact Propositional Gödel Logics

    Microsoft Academic Search

    Matthias Baaz; Richard Zach

    1998-01-01

    Entailment in propositional Godel logics can be defined in a natural way. While all infinite sets of truth values yield the same sets of tautologies, the entailment relations diff er. It is shown that there is a rich structure of infinite-valued Godel logics, only one of which is compact. It is also shown that the compact infinite-valued Godel logic is

  20. ACOUSTIC COMPACTION LAYER DETECTION

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The depth and strength of compacted layers in fields have been determined traditionally using the ASAE standardized cone penetrometer method. However, an on-the-go method would be much faster and much less labor intensive. The soil measurement system described here attempts to locate the compacted...

  1. Compaction properties of isomalt

    Microsoft Academic Search

    Gerad K. Bolhuis; Jeffrey J. P. Engelhart; Anko C. Eissens

    2009-01-01

    Although other polyols have been described extensively as filler-binders in direct compaction of tablets, the polyol isomalt is rather unknown as pharmaceutical excipient, in spite of its description in all the main pharmacopoeias. In this paper the compaction properties of different types of ispomalt were studied. The types used were the standard product sieved isomalt, milled isomalt and two types

  2. The .NET Compact Framework

    Microsoft Academic Search

    C. Neable

    2002-01-01

    The .NET Compact Framework lets developers easily and efficiently build robust applications that call XML Web services, thereby letting end users effectively access remote data, cache it locally for use when offline, and interact with it via rich user interfaces. This paper highlights the .NET Compact Framework's design goals, sheds light on what the first version contains, and speculates on

  3. Powder collection apparatus/method

    DOEpatents

    Anderson, Iver E. (Ames, IA); Terpstra, Robert L. (Ames, IA); Moore, Jeffery A. (Ames, IA)

    1994-01-11

    Device for separating and collecting ultrafine atomized powder from the gas stream of a gas atomizing apparatus comprises a housing having an interior wall oriented at an angle relative to horizontal so as to form a downwardly converging, conical expansion chamber, an inlet conduit communicated to the expansion chamber proximate an upper region thereof for receiving the gas stream, and an outlet proximate a lower region of the expansion chamber. The inlet conduit is oriented at a compound inclined angle (with respect to horizontal) selected to promote separation and collection of powder from the gas stream in the expansion chamber. The compound angle comprises a first entrance angle that is greater than the angle of repose of the powder on the housing interior wall such that any powder accumulation in the inlet conduit tends to flow down the wall toward the outlet. The second angle is selected generally equal to the angle of the housing interior wall measured from the same horizontal plane so as to direct the gas stream into the expansion chamber generally tangent to the housing interior wall to establish a downward swirling gas stream flow in the expansion chamber. A powder collection container is communicated to the outlet of the expansion chamber to collect the powder for further processing.

  4. Powder collection apparatus/method

    DOEpatents

    Anderson, I.E.; Terpstra, R.L.; Moore, J.A.

    1994-01-11

    Device for separating and collecting ultrafine atomized powder from the gas stream of a gas atomizing apparatus comprises a housing having an interior wall oriented at an angle relative to horizontal so as to form a downwardly converging, conical expansion chamber, an inlet conduit communicated to the expansion chamber proximate an upper region thereof for receiving the gas stream, and an outlet proximate a lower region of the expansion chamber. The inlet conduit is oriented at a compound inclined angle (with respect to horizontal) selected to promote separation and collection of powder from the gas stream in the expansion chamber. The compound angle comprises a first entrance angle that is greater than the angle of repose of the powder on the housing interior wall such that any powder accumulation in the inlet conduit tends to flow down the wall toward the outlet. The second angle is selected generally equal to the angle of the housing interior wall measured from the same horizontal plane so as to direct the gas stream into the expansion chamber generally tangent to the housing interior wall to establish a downward swirling gas stream flow in the expansion chamber. A powder collection container is communicated to the outlet of the expansion chamber to collect the powder for further processing. 4 figures.

  5. 30 CFR 57.6901 - Black powder.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...6901 Black powder. (a) Black powder shall be used for...stone. (b) Containers of black powder shall be— (1) Nonsparking...of this section. (c) Black powder shall be transferred...damaged explosives. (f) Holes shall not be reloaded for...

  6. 30 CFR 57.6901 - Black powder.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...6901 Black powder. (a) Black powder shall be used for...stone. (b) Containers of black powder shall be— (1) Nonsparking...of this section. (c) Black powder shall be transferred...damaged explosives. (f) Holes shall not be reloaded for...

  7. 30 CFR 56.6901 - Black powder.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...6901 Black powder. (a) Black powder shall be used for...stone. (b) Containers of black powder shall be— (1) Nonsparking...of this section. (c) Black powder shall be transferred...damaged explosives. (f) Holes shall not be reloaded for...

  8. 30 CFR 56.6901 - Black powder.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...6901 Black powder. (a) Black powder shall be used for...stone. (b) Containers of black powder shall be— (1) Nonsparking...of this section. (c) Black powder shall be transferred...damaged explosives. (f) Holes shall not be reloaded for...

  9. 30 CFR 56.6901 - Black powder.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...6901 Black powder. (a) Black powder shall be used for...stone. (b) Containers of black powder shall be— (1) Nonsparking...of this section. (c) Black powder shall be transferred...damaged explosives. (f) Holes shall not be reloaded for...

  10. 30 CFR 57.6901 - Black powder.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...6901 Black powder. (a) Black powder shall be used for...stone. (b) Containers of black powder shall be— (1) Nonsparking...of this section. (c) Black powder shall be transferred...damaged explosives. (f) Holes shall not be reloaded for...

  11. 30 CFR 56.6901 - Black powder.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...6901 Black powder. (a) Black powder shall be used for...stone. (b) Containers of black powder shall be— (1) Nonsparking...of this section. (c) Black powder shall be transferred...damaged explosives. (f) Holes shall not be reloaded for...

  12. 30 CFR 57.6901 - Black powder.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...6901 Black powder. (a) Black powder shall be used for...stone. (b) Containers of black powder shall be— (1) Nonsparking...of this section. (c) Black powder shall be transferred...damaged explosives. (f) Holes shall not be reloaded for...

  13. 30 CFR 57.6901 - Black powder.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...6901 Black powder. (a) Black powder shall be used for...stone. (b) Containers of black powder shall be— (1) Nonsparking...of this section. (c) Black powder shall be transferred...damaged explosives. (f) Holes shall not be reloaded for...

  14. 30 CFR 56.6901 - Black powder.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...6901 Black powder. (a) Black powder shall be used for...stone. (b) Containers of black powder shall be— (1) Nonsparking...of this section. (c) Black powder shall be transferred...damaged explosives. (f) Holes shall not be reloaded for...

  15. Ceramic oxide powders and the formation thereof

    DOEpatents

    Katz, J.L.; Chenghung Hung.

    1993-12-07

    Ceramic oxide powders and a method for their preparation. Ceramic oxide powders are obtained using a flame process whereby two or more precursors of ceramic oxides are introduced into a counterflow diffusion flame burner wherein said precursors are converted into ceramic oxide powders. The morphology, particle size, and crystalline form of the ceramic oxide powders are determined by process conditions. 14 figures.

  16. Ceramic oxide powders and the formation thereof

    DOEpatents

    Katz, Joseph L. (Baltimore, MD); Hung, Cheng-Hung (Baltimore, MD)

    1993-01-01

    Ceramic oxide powders and a method for their preparation. Ceramic oxide powders are obtained using a flame process whereby two or more precursors of ceramic oxides are introduced into a counterflow diffusion flame burner wherein said precursors are converted into ceramic oxide powders. The morphology, particle size, and crystalline form of the ceramic oxide powders are determined by process conditions.

  17. Stabilization of compactible waste

    SciTech Connect

    Franz, E.M.; Heiser, J.H. III; Colombo, P.

    1990-09-01

    This report summarizes the results of series of experiments performed to determine the feasibility of stabilizing compacted or compactible waste with polymers. The need for this work arose from problems encountered at disposal sites attributed to the instability of this waste in disposal. These studies are part of an experimental program conducted at Brookhaven National Laboratory (BNL) investigating methods for the improved solidification/stabilization of DOE low-level wastes. The approach taken in this study was to perform a series of survey type experiments using various polymerization systems to find the most economical and practical method for further in-depth studies. Compactible dry bulk waste was stabilized with two different monomer systems: styrene-trimethylolpropane trimethacrylate (TMPTMA) and polyester-styrene, in laboratory-scale experiments. Stabilization was accomplished by wetting or soaking compactible waste (before or after compaction) with monomers, which were subsequently polymerized. Three stabilization methods are described. One involves the in-situ treatment of compacted waste with monomers in which a vacuum technique is used to introduce the binder into the waste. The second method involves the alternate placement and compaction of waste and binder into a disposal container. In the third method, the waste is treated before compaction by wetting the waste with the binder using a spraying technique. A series of samples stabilized at various binder-to-waste ratios were evaluated through water immersion and compression testing. Full-scale studies were conducted by stabilizing two 55-gallon drums of real compacted waste. The results of this preliminary study indicate that the integrity of compacted waste forms can be readily improved to ensure their long-term durability in disposal environments. 9 refs., 10 figs., 2 tabs.

  18. Spatio-temporal dynamics behind the shock front from compacted metal nanopowders.

    PubMed

    Leela, Ch; Venkateshwarlu, P; Singh, Raja V; Verma, Pankaj; Kiran, P Prem

    2014-03-10

    Laser ablated shock waves from compacted metal nanoenergetic powders of Aluminum (Al), Nickel coated Aluminum (Ni-Al) was characterized using shadowgraphy technique and compared with that from Boron Potassium Nitrate (BKN), Ammonium Perchlorate (AP) and Potassium Bromide (KBr) powders. Ablation is created by focused second harmonic (532 nm, 7 ns) of Nd:YAG laser. Time resolved shadowgraphs of propagating shock front and contact front revealed dynamics and the precise time of energy release of materials under extreme ablative pressures. Among the different compacted materials studied, Al nanopowders have maximum shock velocity and pressure behind the shock front compared to others. PMID:24922235

  19. Spatio-temporal dynamics behind the shock front from compacted metal nanopowders.

    PubMed

    Leela, Ch; Venkateshwarlu, P; Singh, Raja V; Verma, Pankaj; Kiran, P Prem

    2014-03-10

    Laser ablated shock waves from compacted metal nanoenergetic powders of Aluminum (Al), Nickel coated Aluminum (Ni-Al) was characterized using shadowgraphy technique and compared with that from Boron Potassium Nitrate (BKN), Ammonium Perchlorate (AP) and Potassium Bromide (KBr) powders. Ablation is created by focused second harmonic (532 nm, 7 ns) of Nd:YAG laser. Time resolved shadowgraphs of propagating shock front and contact front revealed dynamics and the precise time of energy release of materials under extreme ablative pressures. Among the different compacted materials studied, Al nanopowders have maximum shock velocity and pressure behind the shock front compared to others. PMID:24800282

  20. Chemical Reactions in the Processing of Mosi2 + Carbon Compacts

    NASA Technical Reports Server (NTRS)

    Jacobson, Nathan S.; Lee, Kang N.; Maloy, Stuart A.; Heuer, Arthur H.

    1993-01-01

    Hot-pressing of MoSi2 powders with carbon at high temperatures reduces the siliceous grain boundary phase in the resultant compact. The chemical reactions in this process were examined using the Knudsen cell technique. A 2.3 wt pct oxygen MoSi2 powder and a 0.59 wt pct oxygen MoSi2 powder, both with additions of 2 wt pct carbon, were examined. The reduction of the siliceous grain boundary phase was examined at 1350 K and the resultant P(SiO)/P(CO) ratios interpreted in terms of the SiO(g) and CO(g) isobars on the Si-C-O predominance diagram. The MoSi2 + carbon mixtures were then heated at the hot-pressing temperature of 2100 K. Large weight losses were observed and could be correlated with the formation of a low-melting eutectic and the formation and vaporization of SiC.

  1. Preparation and characterization of directly compactible layer-by-layer nanocoated cellulose.

    PubMed

    Strydom, Schalk J; Otto, Daniel P; Liebenberg, Wilna; Lvov, Yuri M; de Villiers, Melgardt M

    2011-02-14

    Microcrystalline cellulose is a commonly used direct compression tablet diluent and binder. It is derived from purified ?-cellulose in an environmentally unfriendly process that involves mineral acid catalysed hydrolysis. In this study Kraft softwood fibers was nanocoated using a layer-by-layer self-assembling process. Powder flow and compactibility results showed that the application of nano-thin polymer layers on the fibers turned non-flowing, non-compacting cellulose into powders that can be used in the direct compression of tablets. The powder flow properties and tableting indices of compacts compressed from these nanocoated microfibers were similar or better than that of directly compactible microcrystalline cellulose powders. Cellulose microfibers coated with four PSS/PVP bilayers had the best compaction properties while still producing tablets that were able to absorb water and disintegrate and did not retard the dissolution of a model drug acetaminophen. The advantages of nanocoating rather than traditional pharmaceutical coating are that it add less than 1% to the weight of the fibers and allows control of the molecular properties of the surface and the thickness of the coat to within a few nanometers. This process is potentially friendlier to the environment because of the type and quantity of materials used. Also, it does not involve acid-catalyzed hydrolysis and neutralization of depolymerized cellulose. PMID:21056645

  2. Aspects of the physical metallurgy of creating composite articles made of high-temperature nickel alloys

    SciTech Connect

    Rudnitskii, E.N.; Fatkullin, O.Kh.; Eremenko, V.I.; Pravikova, LA.

    1992-05-01

    One of the advantages of granule metallurgy is the possibility of forming composite articles consisting of different alloys. As elements connected with articles made of granular alloys it is possible to use both granular components and elements prepared by another technology (cast, wrought). Preparation of combined blanks makes it possible solve a number of problems of modern engine building, including preparation of the critical parts of gas turbine engines (compressor and turbine disks, rotor wheels with fixed blades, etc.), whose properties correspond most completely to the temperature and force conditions for operation, and also blanks with inserts which exhibit better production properties cutability, weldability, etc. 2 refs., 5 figs.

  3. Eutectic Sn\\/Pb solder bump and under bump metallurgy: interfacial reactions and adhesion

    Microsoft Academic Search

    Se-Young Jang; Kyung-Wook Paik

    1998-01-01

    In flip-chip interconnection on organic substrates using eutectic tin\\/lead solder bumps, a highly reliable under bump metallurgy (UBM) is required to maintain adhesion and solder wettability. Various UBM systems such as 1?m Al\\/0.2?m Ti\\/5?m Cu, 1?m Al\\/02?m Ti\\/1?m Cu, 1?m Al\\/0.2?m Ni\\/1?m Cu and 1?m Al\\/0.2?m Pd\\/1?m Cu, applied under eutectic tin\\/lead solder bumps, have been investigated with regard to

  4. Energy-Saving Sintering of Electrically Conductive Powders by Modified Pulsed Electric Current Heating Using an Electrically Nonconductive Die

    NASA Astrophysics Data System (ADS)

    Ito, Mikio; Kawahara, Kenta; Araki, Keita

    2014-04-01

    Sintering of Cu and thermoelectric Ca3Co4O9 was tried using a modified pulsed electric current sintering (PECS) process, where an electrically nonconductive die was used instead of a conventional graphite die. The pulsed electric current flowed through graphite punches and sample powder, which caused the Joule heating of the powder compact itself, resulting in sintering under smaller power consumption. Especially for the Ca3Co4O9 powder, densification during sintering was also accelerated by this modified PECS process.

  5. Compact Disc Interactive.

    ERIC Educational Resources Information Center

    Valk, Anton

    1987-01-01

    This overview of a digital optical storage medium with a multimedia capability includes a global description of specifications, current status, and elements required to make a CD-I (compact disk interactive) launch possible. (Author/CLB)

  6. Compact baby Skyrmions

    SciTech Connect

    Adam, C. [Departamento de Fisica de Particulas, Universidad de Santiago and Instituto Galego de Fisica de Altas Enerxias (IGFAE), E-15782 Santiago de Compostela (Spain); Klimas, P. [Instituto de Fisica de Sao Carlos, Universidade de Sao Carlos, Caixa Postal 369, CEP 13560-970, Sao Carlos-SP (Brazil); Sanchez-Guillen, J. [Departamento de Fisica de Particulas, Universidad de Santiago and Instituto Galego de Fisica de Altas Enerxias (IGFAE), E-15782 Santiago de Compostela (Spain); Wereszczynski, A. [Institute of Physics, Jagiellonian University, Reymonta 4, Krakow (Poland)

    2009-11-15

    For the baby Skyrme model with a specific potential, compacton solutions, i.e., configurations with a compact support and parabolic approach to the vacuum, are derived. Specifically, in the nontopological sector, we find spinning Q-balls and Q-shells, as well as peakons. Moreover, we obtain compact baby skyrmions with nontrivial topological charge. All these solutions may form stable multisoliton configurations provided they are sufficiently separated.

  7. Compact homogeneous CR manifolds

    Microsoft Academic Search

    Dmitry V. Alekseevsky; Andrea F. Spiro

    2002-01-01

    We classify all compact simply connected homogeneous CR manifolds M of codimension one and with non-degenerate Levi form up\\u000a to CR equivalence. The classification is based on our previous results and on a description of the maximal connected compact\\u000a group G(M) of automorphisms of M. We characterize also the standard homogeneous CR manifolds as the homogeneous CR manifolds\\u000a whose group

  8. Atom probe study on the bulk nanocomposite SmCo/Fe permanent magnet produced by ball-milling and warm compaction

    E-print Network

    Liu, J. Ping

    compaction of hard magnetic and soft magnetic powders. The raw powder materials, commercial SmCo5 and aFeB/Fe permanent magnets, especially for the high temperature applications. How- ever, for bulk material, howAtom probe study on the bulk nanocomposite SmCo/Fe permanent magnet produced by ball

  9. Anomalous mass transport in Au/304 stainless steel powder under shock loading

    SciTech Connect

    Staudhammer, Karl P.

    2004-01-01

    Dynamic deformation experiments on gold plated 304L stainless steel powders were undertaken using a axial symmetrical implosion geometry. These experiments utilized pressures of 0.08 to 1.0 Mbar and contained a symmetric radial melt region along the central axis of the sample holder. To understand the role of deformation in a porous material, the pressure, and temperature as well as the deformation heat and associated defects must be accounted for. Using a strain controllable shock loading design it was possible to separate and control independently strain and pressure. Thus enabling the ability to control the added heat from the deformation process undergoing compaction/consolidation of the powder. When the added heat of consolidation deformation exceeds the melt temperature of the 304 powders, a melt zone results that can consume large regions of the compact. It is within these regions that very high diffusion of gold into the powder occurs. These anomalous increases have been observed via optical microscopy, scanning electron microscopy and EDAX measurements. Values exceeding 1200 m/sec have been measured and correlated to the powder sizes, size distribution and packing density, concomitant with sample container strains ranging from 2.0% to 26%.

  10. Process design applied to optimise a directly compressible powder produced via a continuous manufacturing process.

    PubMed

    Gonnissen, Y; Gonçalves, S I V; De Geest, B G; Remon, J P; Vervaet, C

    2008-03-01

    Manufacturing of 'ready-to-compress' powder mixtures for direct compression was performed by spray drying, without granulation, milling and/or blending steps in between spray drying and compaction. Powder mixtures containing acetaminophen, mannitol, erythritol, maltodextrin, crospovidone, colloidal silicon dioxide and polyoxyethylene 20 sorbitan monooleate were prepared via co-spray drying. A feed suspension having a solid content of 27.2% w/w was selected for further process optimisation because of its high process yield, excellent flowability and short tablet disintegration time. Experimental design was applied to evaluate processibility, physico-chemical properties and compactability of the spray dried powder mixtures. Significant and adequate regression models were developed for powder flowability, median particle size, bulk density, residual moisture content and process yield. An increasing inlet and outlet drying air temperature improved process yield. However, a higher inlet drying air temperature had a negative influence on density and moisture content, while the latter decreased at higher outlet drying air temperatures. Median particle size increased with a higher inlet temperature, while the outlet temperature had the opposite affect. Numerical optimisation determined the optimal spray drying process (inlet temperature: 221 degrees C, outlet temperature: 81 degrees C and atomisation pressure: 6 bar) in order to produce 'ready-to-compress' powder mixtures. PMID:17964129

  11. Environmental legacy of copper metallurgy and Mongol silver smelting recorded in Yunnan Lake sediments.

    PubMed

    Hillman, Aubrey L; Abbott, Mark B; Yu, JunQing; Bain, Daniel J; Chiou-Peng, TzeHuey

    2015-03-17

    Geochemical measurements on well-dated sediment cores from Lake Er (Erhai) are used to determine the timing of changes in metal concentrations over 4500 years in Yunnan, a borderland region in southwestern China noted for rich mineral deposits but with inadequately documented metallurgical history. Our findings add new insight into the impacts and environmental legacy of human exploitation of metal resources in Yunnan history. We observe an increase in copper at 1500 BC resulting from atmospheric emissions associated with metallurgy. These data clarify the chronological issues related to links between the onset of Yunnan metallurgy and the advent of bronze technology in adjacent Southeast Asia, subjects that have been debated for nearly half a century. We also observe an increase from 1100 to 1300 AD in a number of heavy metals including lead, silver, zinc, and cadmium from atmospheric emissions associated with silver smelting. Culminating during the rule of the Mongols, known as the Yuan Dynasty (1271-1368 AD), these metal concentrations approach levels three to four times higher than those from industrialized mining activity occurring within the catchment today. Notably, the concentrations of lead approach levels at which harmful effects may be observed in aquatic organisms. The persistence of this lead pollution over time created an environmental legacy that likely contributes to known issues in modern day sediment quality. We demonstrate that historic metallurgical production in Yunnan can cause substantial impacts on the sediment quality of lake systems, similar to other paleolimnological findings around the globe. PMID:25685905

  12. Semi Compactness in Multiset Topology

    E-print Network

    J. Mahanta; D. Das

    2014-11-21

    In this paper, we introduce and study the concepts of semi open SOM) and semi closed (SCM) M-sets in multiset topological spaces.With this generalization of the notions of open and closed sets in M-topology, we generalize the concept of compactness in M-topology as semi compactness. Further semi compactness is generalized as semi whole compactness, semi partial whole compactness and semi full compactness. Some characterizations of these compact spaces are studied in the setting of multiset theory. In each step, several remarks with proper justifications are provided taking the well existing theories of general topology as the base of our study.

  13. Characterization and densification studies on ThO 2-UO 2 pellets derived from ThO 2 and U 3O 8 powders

    NASA Astrophysics Data System (ADS)

    Kutty, T. R. G.; Hegde, P. V.; Khan, K. B.; Jarvis, T.; Sengupta, A. K.; Majumdar, S.; Kamath, H. S.

    2004-12-01

    ThO 2 containing around 2-3% 233UO 2 is the proposed fuel for the forthcoming Indian Advanced Heavy Water Reactor (AHWR). This fuel is prepared by powder metallurgy technique using ThO 2 and U 3O 8 powders as the starting material. The densification behaviour of the fuel was evaluated using a high temperature dilatometer in four different atmospheres Ar, Ar-8%H 2, CO 2 and air. Air was found to be the best medium for sintering among them. For Ar and Ar-8%H 2 atmospheres, the former gave a slightly higher densification. Thermogravimetric studies carried out on ThO 2-2%U 3O 8 granules in air showed a continuous decrease in weight up to 1500 °C. The effectiveness of U 3O 8 in enhancing the sintering of ThO 2 has been established.

  14. "Powdered Magnesium: Carbon Dioxide Combustion for Mars Propulsion"

    NASA Technical Reports Server (NTRS)

    Foote, John P.; Litchford, Ron J.

    2005-01-01

    Powdered magnesium - carbon dioxide combustion is examined as a potential in-situ propellant combination for Mars propulsion. Although this particular combination has relatively low performance in comparison to traditional bi-propellants, it remains attractive as a potential basis for future Martian mobility systems since it could be partially or wholly manufactured from indigenous planetary resources. As a means of achieving high mobility during long-duration Mars exploration missions, the poorer performing in-situ combination can, in fact, become a superior alternative to conventional storable propellants, which would need to be entirely transported from earth. Thus, the engineering aspects of powdered metal combustion devices are discussed including transport/injection of compacted powder, ignition, combustion efficiency, combustion stability, dilution effects, lean burn limits, and slag formation issues. It is suggested that these technological issues could be effectively addressed through a multi-phase research and development effort beginning with basic feasibility tests using an existing dump configured atmospheric pressure burner. Follow-on phases would involve the development and testing of a pressurized research combustor and technology demonstration tests of a prototypical rocket configuration.

  15. Crystal coating via spray drying to improve powder tabletability.

    PubMed

    Vanhoorne, V; Peeters, E; Van Snick, B; Remon, J P; Vervaet, C

    2014-11-01

    A continuous crystal coating method was developed to improve both flowability and tabletability of powders. The method includes the introduction of solid, dry particles into an atomized spray during spray drying in order to coat and agglomerate individual particles. Paracetamol was used as a model drug as it exhibits poor flowability and high capping tendency upon compaction. The particle size enlargement and flowability were evaluated by the mean median particle size and flow index of the resulting powders. The crystal coating coprocessing method was successful for the production of powders containing 75% paracetamol with excellent tableting properties. However, the extent of agglomeration achieved during coprocessing was limited. Tablets compressed on a rotary tablet press in manual mode showed excellent compression properties without capping tendency. A formulation with 75% paracetamol, 5% PVP and 20% amorphous lactose yielded a tensile strength of 1.9 MPa at a compression pressure of 288 MPa. The friability of tablets compressed at 188 MPa was only 0.6%. The excellent tabletability of this formulation was attributed to the coating of paracetamol crystals with amorphous lactose and PVP through coprocessing and the presence of brittle and plastic components in the formulation. The coprocessing method was also successfully applied for the production of directly compressible lactose showing improved tensile strength and friability in comparison to a spray dried direct compression lactose grade. PMID:25445306

  16. Laboratory compaction of cohesionless sands 

    E-print Network

    Delphia, John Girard

    1998-01-01

    laboratory compaction methods have focused on determining the maximum This thesis follows the style and format of the Canadian Geotechnical JournaL possible dry unit weight of the soil (i. e. vibrating table compaction test, modified vibrating table... on the effectiveness of laboratory compaction. 2) Determine the effect of three different laboratory compaction procedures (i. e. Standard Proctor, Modified Proctor and the Vibrating Hammer tests) on the compaction of cohesionless sands. 3 ) Correlate the various...

  17. Powder functionality test: a methodology for rheological and mechanical characterization.

    PubMed

    Viana, Marylène; Ribet, Jérome; Rodriguez, Fernand; Chulia, Dominique

    2005-01-01

    In most pharmaceutical formulations, the part of the excipients, in quantity and number, is larger than that of active principles, justifying particular attention to their characteristics to ensure quality, efficacy, and reproducibility of final forms. Whereas chemical specifications are described in Pharmacopeias, physical characteristics, up to now, have not been sufficiently considered. Nevertheless, there is a need for tests to objectively compare technological performances of products and justify composition of medicinal products. The powder functionality test described in this article is based on the analysis of the global behavior of materials under pressure. The powder compression is performed using an instrumented uniaxial press, Lloyd 6000R, and a compression cell of 1 cm3 in volume, allowing a complete and early characterization with a few grams of material. Indices characterizing packing, densification energies, energetic yields, and deformation mode of the particles are proposed from the analysis of compression cycles. Cohesion and energy of rupture are deduced from the diametral rupture cycles of the compacts. Application of this methodology to supplied celluloses has shown better flow properties of microcrystalline celluloses due to their higher bulk density and particle size. The energy fraction lost as frictions is very important and independent of the type of celluloses, whereas elastic energy is higher for powdered celluloses P100 and G250. Finally the efficacy to convert compaction energy into cohesion is higher for products with a small degree of polymerization, i.e., microcrystalline celluloses, except A301 and A302, which also are distinguished by their low porosity. PMID:15926682

  18. Physically detached 'compact groups'

    NASA Technical Reports Server (NTRS)

    Hernquist, Lars; Katz, Neal; Weinberg, David H.

    1995-01-01

    A small fraction of galaxies appear to reside in dense compact groups, whose inferred crossing times are much shorter than a Hubble time. These short crossing times have led to considerable disagreement among researchers attempting to deduce the dynamical state of these systems. In this paper, we suggest that many of the observed groups are not physically bound but are chance projections of galaxies well separated along the line of sight. Unlike earlier similar proposals, ours does not require that the galaxies in the compact group be members of a more diffuse, but physically bound entity. The probability of physically separated galaxies projecting into an apparent compact group is nonnegligible if most galaxies are distributed in thin filaments. We illustrate this general point with a specific example: a simulation of a cold dark matter universe, in which hydrodynamic effects are included to identify galaxies. The simulated galaxy distribution is filamentary and end-on views of these filaments produce apparent galaxy associations that have sizes and velocity dispersions similar to those of observed compact groups. The frequency of such projections is sufficient, in principle, to explain the observed space density of groups in the Hickson catalog. We discuss the implications of our proposal for the formation and evolution of groups and elliptical galaxies. The proposal can be tested by using redshift-independent distance estimators to measure the line-of-sight spatial extent of nearby compact groups.

  19. Intradermal needle-free powdered drug injection

    E-print Network

    Liu, John (John Hsiao-Yung)

    2012-01-01

    This thesis presents a new method for needle-free powdered drug injection. The design, construction, and testing of a bench-top helium-powered device capable of delivering powder to controllable depths within the dermis ...

  20. Two-dimensional distribution of carbon nanotubes in copper flake powders.

    PubMed

    Tan, Zhanqiu; Li, Zhiqiang; Fan, Genlian; Li, Wenhuan; Liu, Qinglei; Zhang, Wang; Zhang, Di

    2011-06-01

    We report an approach of flake powder metallurgy to the uniform, two-dimensional (2D) distribution of carbon nanotubes (CNTs) in Cu flake powders. It consists of the preparation of Cu flakes by ball milling in an imidazoline derivative (IMD) aqueous solution, surface modification of Cu flakes with polyvinyl alcohol (PVA) hydrosol and adsorption of CNTs from a CNT aqueous suspension. During ball milling, a hydrophobic monolayer of IMD is adsorbed on the surface of the Cu flakes, on top of which a hydrophilic PVA film is adsorbed subsequently. This PVA film could further interact with the carboxyl-group functionalized CNTs and act to lock the CNTs onto the surfaces of the Cu flakes. The CNT volume fraction is controlled easily by adjusting the concentration/volume of CNT aqueous suspension and Cu flake thickness. The as-prepared CNT/Cu composite flakes will serve as suitable building blocks for the self-assembly of CNT/Cu laminated composites that enable the full potential of 2D distributed CNTs to achieve high thermal conductivity. PMID:21454945

  1. Review: aqueous tape casting of ceramic powders

    Microsoft Academic Search

    D. Hotza; P. Greil

    1995-01-01

    Slurry formulations and processing parameters of the water-based tape casting of ceramic powders are reviewed. Additives include binders, like cellulose ethers, vinyl or acrylic-type polymers; plasticizers, like glycols; and dispersants, like ammonium salts of poly(acrylic acids). Mostly alumina powders have been employed. Hydrophobing of ceramic powders permits the aqueous processing even of water-reactive powders, like aluminium nitride. Non-toxicity and non-inflammability

  2. Mounting of high power laser diodes on boron nitride heat sinks using an optimized Au\\/Sn metallurgy

    Microsoft Academic Search

    Wolfgang Pittroff; Goetz Erbert; Gert Beister; Frank Bugge; Achim Klein; Arne Knauer; Juergen Maege; Peter Ressel; Juergen Sebastian; Ralf Staske; Guenther Traenkle

    2001-01-01

    High power diode lasers have become more and more important to industrial and medical applications. In contrast to low power applications, long cavity lasers or laser bars are used in this field and mounting quality influences considerably laser performance and life time. In this paper we focus on the solder metallurgy and stress-induced laser behavior after mounting. The laser chips

  3. B.G. Thomas, "Continuous Casting", Yearbook of Science and Technology, McGraw-Hill, 2004. 1 Continuous Casting (metallurgy)

    E-print Network

    Thomas, Brian G.

    exist (Fig. 1). Vertical machines cast aluminum and a few special alloys. Curved machines are usedB.G. Thomas, "Continuous Casting", Yearbook of Science and Technology, McGraw-Hill, 2004. 1 Continuous Casting (metallurgy) B.G. Thomas Mechanical & Industrial Engineering University of Illinois

  4. Materials Science & Metallurgy Master of Philosophy, Materials Modelling, Course MP4, Thermodynamics and Phase Diagrams, H. K. D. H. Bhadeshia

    E-print Network

    Cambridge, University of

    Materials Science & Metallurgy Master of Philosophy, Materials Modelling, Course MP4 factors contribute to the heat capacity of a polymer? 4. Explain why ordered crystals become disordered as follows (Kirkaldy and Baganis, Metall. Trans. 9A, 1978, 495): ln{C} = 8.1 × xC - 5 × xMn where x

  5. 21 CFR 524.1005 - Furazolidone powder.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...2014-04-01 false Furazolidone powder. 524.1005 Section 524... § 524.1005 Furazolidone powder. (a) Specifications...affected area and apply only enough powder to impart a light yellow color...lacerations, and following firing (heat or electrocautery)....

  6. 21 CFR 73.1647 - Copper powder.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...2010-04-01 2010-04-01 false Copper powder. 73.1647 Section 73.1647...FROM CERTIFICATION Drugs § 73.1647 Copper powder. (a) Identity. (1) The color additive copper powder is a very fine free-flowing...

  7. 21 CFR 73.1647 - Copper powder.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...2013-04-01 2013-04-01 false Copper powder. 73.1647 Section 73.1647...FROM CERTIFICATION Drugs § 73.1647 Copper powder. (a) Identity. (1) The color additive copper powder is a very fine free-flowing...

  8. 21 CFR 73.1647 - Copper powder.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...2014-04-01 2014-04-01 false Copper powder. 73.1647 Section 73.1647...FROM CERTIFICATION Drugs § 73.1647 Copper powder. (a) Identity. (1) The color additive copper powder is a very fine free-flowing...

  9. 21 CFR 73.1647 - Copper powder.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...2011-04-01 2011-04-01 false Copper powder. 73.1647 Section 73.1647...FROM CERTIFICATION Drugs § 73.1647 Copper powder. (a) Identity. (1) The color additive copper powder is a very fine free-flowing...

  10. 21 CFR 73.1647 - Copper powder.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...2012-04-01 2012-04-01 false Copper powder. 73.1647 Section 73.1647...FROM CERTIFICATION Drugs § 73.1647 Copper powder. (a) Identity. (1) The color additive copper powder is a very fine free-flowing...

  11. Effect of Powder Polydispersity on Aerosol Generation

    Microsoft Academic Search

    Nora Y. K. Chew; Hak-Kim Chan

    Purpose. We investigated the effect of primary powder polydispersity on the generation of pharmaceutical powder aerosols, using mannitol and bovine serum albu- min (BSA) as the model compounds. Methods. Primary powders with different polydispersity but comparable physical and mass median aerodynamic diameter (MMAD) were obtained from spray drying. The polydispersity, i.e. the width of the particle size distribution, of the

  12. Investigation of deformation micro-mechanisms in nickel consolidated from a bimodal powder by spark plasma sintering

    E-print Network

    Gubicza, Jenõ

    Investigation of deformation micro-mechanisms in nickel consolidated from a bimodal powder by spark 11 November 2014 Available online 20 November 2014 Keywords: Nickel Spark plasma sintering Bimodal structure Dislocation In-situ TEM Bulk polycrystalline nickel compact was processed by spark plasma

  13. Compaction and elastic unloading of nanopowders in terms of granular dynamics

    NASA Astrophysics Data System (ADS)

    Boltachev, G. Sh.; Volkov, N. B.; Dvilis, E. S.; Khasanov, O. L.

    2015-02-01

    The behavior of nanopowders is simulated by a granular dynamics method. The elastic interaction of individual particles is described in terms of the rod model of contact, which is the generalization of the classical Hertz law and can be applied in the case of relatively strong particle deformation. The processes of uniaxial compression/tension in a rigid matrix are analyzed. The calculated data on the elastic properties of model systems are compared to the experimental data obtained for oxide nanopowders. The simulation of unloading (tension) makes it possible to separate the plastic irreversible part and the elastic part in the total strain of a powder body. The effect of the particle size on the elastic properties and the final density of the powder compact is studied, and the residual lateral stresses in powder compacts after the removal of an axial load and the maximum oxide nanopowder densities reached at high pressures are estimated.

  14. Particle adhesion in powder coating

    SciTech Connect

    Mazumder, M.K.; Wankum, D.L.; Knutson, M.; Williams, S. [Univ. of Arkansas, Little Rock, AR (United States); Banerjee, S. [Univ. of Georgia, Athens, GA (United States)

    1996-12-31

    Electrostatic powder coating is a widely used industrial painting process. It has three major advantages: (1) it provides high quality durable finish, (2) the process is environmentally friendly and does not require the use of organic solvents, and (3) it is economically competitive. The adhesion of electrostatically deposited polymer paint particles on the grounded conducting substrate depends upon many parameters: (a) particle size and shape distributions, (b) electrostatic charge distributions, (c) electrical resistivity, (d) dielectric strength of the particles, (e) thickness of the powder film, (f) presence and severity of the back corona, and (g) the conductivity and surface properties of the substrate. The authors present a model on the forces of deposition and adhesion of corona charged particles on conducting substrates.

  15. Analysis of powder diffraction data

    Microsoft Academic Search

    M. J. Cooper

    1982-01-01

    A comparison has been carried out between the results of analyses of several sets of neutron powder diffraction data using three different methods: the Rietveld method (H.M. Rietveld, Acta. Cryst. 2, 151-152 (1967): J. Appl. Cryst. 2, 65-71 (1969), a modification of the Rietveld method to include off-diagonal terms in the weight matrix (C.P. Clarke and J.S. Rollett, Acta. Cryst.

  16. Compact Stellarator Development Plan

    E-print Network

    Development Through Proof of Principle (PoP) and Performance Extension (PE) to DEMO ­ Key Milestones and foreign PE stellarators. · Focus U.S. compact stellarator experiments on 3D physics issues. Can lead Helical Device (PE w/ S/C magnets - Japan) > 3%. Te 10 kev, Ti 5 keV. enhanced confinement. 2-minute

  17. Compact, Integrated Photoelectron Linacs

    Microsoft Academic Search

    David Yu

    2000-01-01

    The innovative compact high energy iniector which has been developed by DULY Research Inc., will have wide scientific industrial and medical applications. The new photoelectron injector integrates the photocathode directly into a multicell linear accelerator with no drift space between the injector and the linac. By focusing the beam with solenoid or permanent magnets, and producing high current with low

  18. COMPACT SCHOOL AND $$ SAVINGS.

    ERIC Educational Resources Information Center

    BAIR, W.G.

    A REVIEW OF THE CRITERIA FOR CONSIDERING THE USE OF A TOTAL ENERGY SYSTEM WITHIN A SCHOOL BUILDING STATES THE WINDOWLESS, COMPACT SCHOOL OFFERS MORE EFFICIENT SPACE UTILIZATION WITH LESS AREA REQUIRED FOR GIVEN STUDENT POPULATION AND LOWER OPERATION COSTS. THE AUTHOR RECOMMENDS THAT THESE BUILDINGS BE WINDOWLESS TO REDUCE HEAT COSTS, HOWEVER, AT…

  19. Compact fusion reactors

    SciTech Connect

    Krakowski, R.A.; Hagenson, R.L.

    1983-01-01

    Compact, high-power-density approaches to fusion power are proposed to improve economic viability through the use of less-advanced technology in systems of considerably reduced scale. The rationale for and the means by which these systems can be achieved are discussed, as are unique technological problems.

  20. Physical and mechanical metallurgy of high purity Nb for accelerator cavities

    SciTech Connect

    Bieler, T. R. [Michigan State University, East Lansing; Wright, N. T. [Michigan State University, East Lansing; Pourboghrat, F. [Michigan State University, East Lansing; Compton, C. [Michigan State University, East Lansing; Hartwig, K. T. [Texas A& M University; Baars, D. [Michigan State University, East Lansing; Zamiri, A. [Michigan State University, East Lansing; Chandrasekaran, S. [Michigan State University, East Lansing; Darbandi, P. [Michigan State University, East Lansing; Jiang, H. [Michigan State University, East Lansing; Skoug, E. [Michigan State University, East Lansing; Balachandran, S. [Texas A& M University; Ice, Gene E [ORNL; Liu, W. [Argonne National Laboratory (ANL)

    2010-01-01

    In the past decade, high Q values have been achieved in high purity Nb superconducting radio frequency (SRF) cavities. Fundamental understanding of the physical metallurgy of Nb that enables these achievements is beginning to reveal what challenges remain to establish reproducible and cost-effective production of high performance SRF cavities. Recent studies of dislocation substructure development and effects of recrystallization arising from welding and heat treatments and their correlations with cavity performance are considered. With better fundamental understanding of the effects of dislocation substructure evolution and recrystallization on electron and phonon conduction, as well as the interior and surface states, it will be possible to design optimal processing paths for cost-effective performance using approaches such as hydroforming, which minimizes or eliminates welds in a cavity.