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1

Workability in forging of powder metallurgy compacts  

Microsoft Academic Search

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

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

1995-01-01

2

Effect of die wall lubrication on warm compaction powder metallurgy  

Microsoft Academic Search

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

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

2002-01-01

3

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

NASA Astrophysics Data System (ADS)

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.

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

2000-05-01

4

Metallography of powder metallurgy materials  

Microsoft Academic Search

The primary distinction between the microstructure of an ingot metallurgy\\/wrought material and one fabricated by the powder metallurgy route of pressing followed by sintering is the presence of porosity in the latter. In its various morphologies, porosity affects the mechanical, physical, chemical, electrical and thermal properties of the material. Thus, it is important to be able to characterize quantitatively the

Alan Lawley; Thomas F. Murphy

2003-01-01

5

Metallography of powder metallurgy materials  

SciTech Connect

The primary distinction between the microstructure of an ingot metallurgy/wrought material and one fabricated by the powder metallurgy route of pressing followed by sintering is the presence of porosity in the latter. In its various morphologies, porosity affects the mechanical, physical, chemical, electrical and thermal properties of the material. Thus, it is important to be able to characterize quantitatively the microstructure of powder metallurgy parts and components. Metallographic procedures necessary for the reliable characterization of microstructures in powder metallurgy materials are reviewed, with emphasis on the intrinsic challenges presented by the presence of porosity. To illustrate the utility of these techniques, five case studies are presented involving powder metallurgy materials. These case studies demonstrate problem solving via metallography in diverse situations: failure of a tungsten carbide-coated precipitation hardening stainless steel, failure of a steel pump gear, quantification of the degree of sinter (DOS), simulation of performance of a porous filter using automated image analysis, and analysis of failure in a sinter brazed part assembly.

Lawley, Alan; Murphy, Thomas F

2003-12-15

6

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

Microsoft Academic Search

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

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

2011-01-01

7

Magnesium Powder Metallurgy: Process and Materials Opportunities  

NASA Astrophysics Data System (ADS)

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.

Bettles, Colleen J.

2008-06-01

8

Aluminum-lithium powder metallurgy alloys with improved toughness  

NASA Astrophysics Data System (ADS)

A technique has been developed for increasing the toughness of Al-Li products made by powder metallurgy. The technique which involves forming a duplex structure by the addition of unalloyed aluminum powder to Al-Li powder before compaction was evaluated with Al-Li-Cu-Mg-Zr alloys (A18090). The strength, ductility, toughness, and short transverse stress corrosion resistance of the alloys were determined. The addition of 15 pct aluminum to A18090 aged at 422 K for 40 hours produced an increase in impact toughness of 215 pct at the expense of a drop in yield strength of 11 pct. The powder metallurgy alloys with a duplex structure had superior longitudinal strengthtoughness combinations to ingot materials of similar composition processed identically.

Webster, D.

1988-03-01

9

Ti Multicomponent Alloy Bulks by Powder Metallurgy  

NASA Astrophysics Data System (ADS)

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.

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

2014-10-01

10

Ceramic powder compaction  

SciTech Connect

With the objective of developing a predictive model for ceramic powder compaction we have investigated methods for characterizing density gradients in ceramic powder compacts, reviewed and compared existing compaction models, conducted compaction experiments on a spray dried alumina powder, and conducted mechanical tests and compaction experiments on model granular materials. Die filling and particle packing, and the behavior of individual granules play an important role in determining compaction behavior and should be incorporated into realistic compaction models. These results support the use of discrete element modeling techniques and statistical mechanics principals to develop a comprehensive model for compaction, something that should be achievable with computers with parallel processing capabilities.

Glass, S.J.; Ewsuk, K.G. [Sandia National Labs., Albuquerque, NM (United States); Mahoney, F.M. [Norton Co., Worcester, MA (United States)

1995-12-31

11

Biaxially textured articles formed by powder metallurgy  

DOEpatents

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.

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

2001-01-01

12

Superplastic deformation mechanism in powder metallurgy magnesium alloys and composites  

Microsoft Academic Search

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

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

2001-01-01

13

Sintering of powder mixtures and the growth of ferrous powder metallurgy  

Microsoft Academic Search

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;

K. S Narasimhan

2001-01-01

14

Powder metallurgy process for manufacturing core projectile  

NASA Astrophysics Data System (ADS)

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.

Akbar, Taufik; Setyowati, Vuri Ayu; Widyastuti

2013-09-01

15

Advances in powder metallurgy; Proceedings of the 1989 Powder Metallurgy Conference and Exhibition, San Diego, CA, June 11-14, 1989. Volumes 1, 2, 3  

SciTech Connect

Recent advances in powder-metallurgy (PM) techniques and the applications of PM materials are discussed in reviews and reports. Sections are devoted to blending technologies, compressibility, compaction processes, enhanced sintering, high-temperature sintering, postsinter heat treatment, powder forging, alloy development, mechanical properties, PM testing and characterization, statistical process control, powder production techniques, and spray forming. Consideration is given to Al and Cu alloys, stainless and tool steels, heavy metals, high-performance materials, superconductors and magnetic materials, metal injection molding, and PM aerospace materials. Extensive diagrams, drawings, graphs, micrographs, and tables of numerical data are provided.

Gasbarre, T.G.; Jandeska, W.F. Jr.

1989-01-01

16

Aluminium powder metallurgy technology for high-strength applications  

Microsoft Academic Search

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

J. R. Pickens

1981-01-01

17

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

E-print Network

In vitro degradation and cytotoxicity of Mg/Ca composites produced by powder metallurgy q Y Biodegradation Cytotoxicity Powder metallurgy a b s t r a c t 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

Zheng, Yufeng

18

Development of Magnesium Powder Metallurgy AZ31 Alloy Using Commercially Available Powders  

NASA Astrophysics Data System (ADS)

Magnesium and its alloys are attractive materials for use in automotive and aerospace applications because of their low density and good mechanical properties. However, difficulty in forming magnesium and the limited number of available commercial alloys limit their use. The present work reviews the efforts to improve the attractiveness of magnesium through non-traditional processing, and presents the results of producing AZ31 magnesium alloy via powder metallurgy P/M. P/M can be used to alleviate the formability problem through near-net-shape processing, and also allows unique chemical compositions that can lead to the development of new alloys with novel properties. The feasibility of producing magnesium powder metallurgy products utilizing the industrially dominant process of mixed powder blending, uni-axial die compaction and controlled atmosphere sintering was investigated. An alloy composition based on the commercial Mg alloy AZ31 (3 mass % Al, 1 mass % Zn) was used to facilitate the comparison to similar wrought product. The optimal processing conditions (compaction pressure, sintering time and temperature) were found to maximize sintered density and mechanical properties. Results show that sintering temperature is one of the major variables that has an appreciable effect on the final properties of the samples, and that the effects of compaction pressure and sintering time were insignificant. The material showed poor tensile properties, with a maximum tensile strength of 32 MPa due to lack of sufficient densification. The latter was related to the lack of liquid phase formed during sintering of Al/Zn magnesium alloys and the barrier to diffusion due to the presence of the stable magnesium surface layer.

Burke, Paul; Kipouros, Georges J.

2011-04-01

19

Compaction of Titanium Powders  

SciTech Connect

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.

Gerdemann, Stephen,J; Jablonski, Paul, J

2011-05-01

20

Compaction of Titanium Powders  

NASA Astrophysics Data System (ADS)

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.

Gerdemann, Stephen J.; Jablonski, Paul D.

2011-05-01

21

Generalised yield criteria of porous sintered powder metallurgy metals  

Microsoft Academic Search

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

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

2001-01-01

22

Scaleup of powder metallurgy processed Nb-Al multifilamentary wire  

Microsoft Academic Search

Power metallurgy processed Nb-Al superconducting wires were fabricated from billets up to 45 mm o.d. with nominal areal reduction ratios, R, up to 2 X 10⁵, Nb powder sizes from 40 to 300 ..mu..m from various sources, Al powder sizes from 9 to 75 ..mu..m, Al concentrations from 3 to 25 wt % Al and with a wide range of

C. Thieme; H. Zhang; J. Otubo; S. Pourrahimi; B. Schwartz; S. Foner

1983-01-01

23

Properties of Highly-Dense Iron?Base Powder Metallurgy Materials Pressed without Zinc Stearate  

Microsoft Academic Search

The possibility of obtaining highly-dense compacts by single pressing and sintering and the use of heat-resistant solid lubricants (graphite, talc) instead of conventional lubricant was studied. It was shown that the addition of graphite is most effective to obtain highly-dense powder metallurgy materials since it substantially facilitates ejection of the part from the die and improves the mechanical properties.

Arif T. Mamedov; V. A. Mamedov

2003-01-01

24

Generalized mathematical model of thermal diffusion in powder metallurgy  

NASA Astrophysics Data System (ADS)

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.

Lyashenko, V.; Hryhorova, Ð.¢.

2014-11-01

25

A powder metallurgy approach for production of innovative radioactive waste forms  

SciTech Connect

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.

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

26

Powder metallurgy titanium 6A1-4V plate  

SciTech Connect

A powder metallurgical approach has been combined with controlled mill processing to produce a highly uniform plate material suitable for structural applications. Prealloyed ELI Titanium 6A1-4V powder produced by the rotating electrode process was consolidated into billet by hot isostatic pressing. The resulting billet of uniform composition and random texture was then hot cross-rolled to 3 cm thick plate. Following rolling, the plate was given a beta annealing heat treatment to maximize damage tolerance. The plate was characterized with respect to metallurgical structure, composition, texture, and room temperature mechanical properties. The results of the study show that a powder metallurgy titanium mill product possessing uniform macro- and microstructure is technically feasible and exhibits tensile and fatigue properties equivalent to those of conventionally produced ingot-source wrought plate.

Geisendorfer, R.F.

1980-01-01

27

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

Microsoft Academic Search

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

C. Q. Ning; Y. Zhou

2002-01-01

28

DC Plasma Technology Applied to Powder Metallurgy: an Overview  

NASA Astrophysics Data System (ADS)

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.

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

29

Novel synthesis of high phase-purity Mg2SnO4 from metallic precursors via powder metallurgy route  

E-print Network

Novel synthesis of high phase-purity Mg2SnO4 from metallic precursors via powder metallurgy route of composition Mg2Sn was prepared by the conventional powder metallurgy route. This up on heating in air under

Azad, Abdul-Majeed

30

N18, powder metallurgy superalloy for disks: Development and applications  

SciTech Connect

The preliminary industrial development of a powder metallurgy (PM) superalloy, designated N18, for disk applications has been completed. This alloy exhibits good overall mechanical properties after appropriate processing of the material. These properties have been measured on both isothermally forged and extruded billets, as well as on specimens cut from actual parts. The temperature capability of the alloy is about 700 C for long-term applications and approximately 750 C for short-term use because of microstructural instability. Further improvements in creep and crack propagation properties, without significant reduction in tensile strength, are possible through appropriate thermomechanical processing, which results in a large controlled grain size. Spin pit tests on subscale disks have confirmed that the N18 alloy has a higher resistance than PM Astrology and is therefore an excellent alloy for modern turbine disk applications.

Guedou, J.Y.; Lautridou, J.C.; Honnorat, Y. (SNECMA, Evry (France). Materials and Processes Dept.)

1993-08-01

31

Method for forming biaxially textured articles by powder metallurgy  

DOEpatents

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.

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

2002-01-01

32

MESOSCALE SIMULATIONS OF POWDER COMPACTION  

SciTech Connect

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.

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

2009-12-28

33

Shock compaction of molybdenum powder  

NASA Technical Reports Server (NTRS)

Shock recovery experiments which were carried out in the 9 to 12 GPa range on 1.4 distension Mo and appear adequate to compact to full density ( 45 (SIGMA)m) powders were examined. The stress levels, however, are below those calculated to be from 100 to approx. 22 GPa which a frictional heating model predicts are required to consolidate approx. 10 to 50 (SIGMA)m particles. The model predicts that powders that have a distension of m=1.6 shock pressures of 14 to 72 GPa are required to consolidate Mo powders in the 50 to 10 (SIGMA)m range.

Ahrens, T. J.; Kostka, D.; Vreeland, T., Jr.; Schwarz, R. B.; Kasiraj, P.

1983-01-01

34

Powder metallurgy approach for control of microstructure and properties in high strength aluminum alloys  

Microsoft Academic Search

High-strength products made from atomized Al-Zn-Mg-Cu-Co alloy powders have good combinations of strength, ductility, resistance to stress-corrosion cracking and fracture toughness. Powder Metallurgy (PJM) methods produce fine metallurgical structures and compositions which cannot be produced by Ingot Metallurgy (IJM) methods. Fine structures result from very rapid solidification and from the effect of fine dispersoids in restricting grain growth. Stress-corrosion cracking

J. P. Lyle; W. S. Cebulak

1975-01-01

35

A study on the development of a substitution process by powder metallurgy in automobile parts  

Microsoft Academic Search

Powder metallurgy processes using sintering are able to form net-shaped products and have been used widely in the production of automobile parts to improve productivity. However, the toughness of powder products is generally poor because they contain pores. Therefore, forged products are used in parts subjected to severe fatigue loads, but in the case of powder products having high toughness,

G. B Jang; M. D Hur; S. S Kang

2000-01-01

36

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

Microsoft Academic Search

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

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

2000-01-01

37

Thixoforming of Stellite Powder Compacts  

NASA Astrophysics Data System (ADS)

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.

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

2007-04-01

38

Powder metallurgy approach for control of microstructure and properties in high strength aluminum alloys  

Microsoft Academic Search

High-strength products made from atomized Al-Zn-Mg-Cu-Co alloy powders have good combinations of strength, ductility, resistance\\u000a to stress-corrosion cracking and fracture toughness. Powder Metallurgy (PJM) methods produce fine metallurgical structures\\u000a and compositions which cannot be produced by Ingot Metallurgy (IJM) methods.\\u000a \\u000a Fine structures result from very rapid solidification and from the effect of fine dispersoids in restricting grain growth.\\u000a Stress-corrosion cracking

J. P. Lyle; W. S. Cebulak

1975-01-01

39

Fabrication of Powder Metallurgy Pure Ti Material by Using Thermal Decomposition of TiH2  

NASA Astrophysics Data System (ADS)

Titanium (Ti) and titanium alloys have been interested as an engineering material because they are widely used across various industrial applications, for example, motorcycle, automotive and aerospace industries, due to their light weight, high specific strength and superior corrosion resistance. Ti materials are particularly significant for the aircraft using carbon/carbon (C/C) composites, for example, carbon fiber reinforced plastics (CFRP), because Ti materials are free from the problem of contact corrosion between C/C composites. However, the applications of Ti materials are limited because of their high cost. From a viewpoint of cost reduction, cost effective process to fabricate Ti materials is strongly required. In the present study, the direct consolidation of titanium hydride (TiH2) raw powders in solid-state was employed to fabricate pure Ti bulk materials by using thermal decomposition of TiH2. In general, the production cost of Ti components is expensive due to using commercially pure (CP) Ti powders after dehydrogenation. On the other hand, the novel process using TiH2 powders as starting materials is a promising low cost approach for powder metallurgy (P/M) Ti products. Furthermore, this new process is also attractive from a viewpoint of energy saving because the dehydrogenation is integrated into the sintering process. In this study, TiH2 raw powders were directly consolidated by conventional press technique at 600 MPa to prepare TiH2 powder compacted billets. To thermally decompose TiH2 and obtain sintered pure Ti billets, the TiH2 powder billets were heated in the integrated sintering process including dehydrogenation. The hot-extruded pure Ti material, which was heat treated at 1273 K for 180 min in argon gas atmosphere, showed tensile strength of 701.8 MPa and elongation of 27.1%. These tensile properties satisfied the requirements for JIS Ti Grade 4. The relationship between microstructures, mechanical properties response and heat treatment temperature is discussed in detail.

Mimoto, Takanori; Nakanishi, Nozomi; Umeda, Junko; Kondoh, Katsuyoshi

40

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

E-print Network

1 A novel powder metallurgy-based method for the recycling of aluminum adapted to a small island volume scrap aluminum, the application of the powder metallurgy process is proposed. Its methodology of the advantages of the powder metallurgy process. The properties of the recycled parts make them competitive

Boyer, Edmond

41

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

Microsoft Academic Search

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

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

2005-01-01

42

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

Microsoft Academic Search

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

G. S. Upadhyaya

1995-01-01

43

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

Microsoft Academic Search

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

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

2002-01-01

44

Production of a Low Young Modulus Titanium Alloy by Powder Metallurgy  

Microsoft Academic Search

Titanium alloys have several advantages over ferrous and non-ferrous metallic materials, such as high strength-to- weight ratio and excellent corrosion resistance. A blended elemental titanium powder metallurgy process has been developed to offer low cost commercial products. The process employs hydride-dehydride (HDH) powders as raw material. In this work, results of the Ti-35Nb alloy sintering are presented. This alloy due

Dalcy Roberto dos Santos; Vinicius André; Rodrigues Henriques; Carlos Alberto; Alves Cairo

2005-01-01

45

Influence of graphite content on the dry sliding and oil impregnated sliding wear behavior of Al 2024–graphite composites produced by in situ powder metallurgy method  

Microsoft Academic Search

The influence of graphite content on the dry sliding and oil impregnated sliding wear characteristics of sintered aluminum 2024 alloy–graphite (Al\\/Gr) composite materials has been assessed using a pin-on-disc wear test. The composites with 5–20wt.% flake graphite particles were processed by in situ powder metallurgy technique. For comparison, compacts of the base alloy were made under the same consolidation processing

F. Akhlaghi; A. Zare-Bidaki

2009-01-01

46

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

NASA Astrophysics Data System (ADS)

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.

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

2012-09-01

47

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

PubMed

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

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

2010-05-01

48

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

Microsoft Academic Search

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' particles in a gamma matrix. The higher cobalt-content alloys contained larger amounts of the

Fredric H. Harf

1985-01-01

49

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

Microsoft Academic Search

Nickel was substituted in various proportions for cobalt in a series of five hot-isostatically-pressed powder metallurgy alloys\\u000a based on the UDIMET 700 composition. These alloys were given 5-step heat treatments appropriate for use in turbine engine\\u000a disks. The resultant microstructures displayed three distinct sizes of ?? particles in a ? matrix. The higher cobalt-content\\u000a alloys contained larger amounts of the

Fredric H. Harf

1985-01-01

50

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

Microsoft Academic Search

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

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

1994-01-01

51

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

Microsoft Academic Search

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

J. S. Agapiou; M. F. DeVries

1989-01-01

52

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

Microsoft Academic Search

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.

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

2006-01-01

53

Properties of magnetocaloric La(Fe,Co,Si) 13 produced by powder metallurgy  

Microsoft Academic Search

We present a comprehensive study of the magnetocaloric materials series La(Fe1?xCox)11.9Si1.1 with 0.055x0.122. The ferromagnetic samples were manufactured using a novel powder metallurgy process by which industrial scale production is feasible. This new production method makes the materials more attractive as magnetic refrigerants for room temperature magnetic refrigeration. The Curie temperature of the compounds can be easily tuned by altering

Britt Rosendahl Hansen; L. Theil Kuhn; C. R. H. Bahl; M. Lundberg; C. Ancona-Torres; M. Katter

2010-01-01

54

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

SciTech Connect

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.

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

55

Micro powder metallurgy for the replicative production of metallic microstructures  

Microsoft Academic Search

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

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

2002-01-01

56

Dynamic compaction of tungsten carbide powder.  

SciTech Connect

The shock compaction behavior of a tungsten carbide powder was investigated using a new experimental design for gas-gun experiments. This design allows the Hugoniot properties to be measured with reasonably good accuracy despite the inherent difficulties involved with distended powders. The experiments also provide the first reshock state for the compacted powder. Experiments were conducted at impact velocities of 245, 500, and 711 m/s. A steady shock wave was observed for some of the sample thicknesses, but the remainder were attenuated due to release from the back of the impactor or the edge of the sample. The shock velocity for the powder was found to be quite low, and the propagating shock waves were seen to be very dispersive. The Hugoniot density for the 711 m/s experiment was close to ambient crystal density for tungsten carbide, indicating nearly complete compaction. When compared with quasi-static compaction results for the same material, the dynamic compaction data is seen to be significantly stiffer for the regime over which they overlap. Based on these initial results, recommendations are made for improving the experimental technique and for future work to improve our understanding of powder compaction.

Gluth, Jeffrey Weston; Hall, Clint Allen; Vogler, Tracy John; Grady, Dennis Edward

2005-04-01

57

Net-Shape HIP Powder Metallurgy Components for Rocket Engines  

NASA Technical Reports Server (NTRS)

True net shape consolidation of powder metal (PM) by hot isostatic pressing (HIP) provides opportunities for many cost, performance and life benefits over conventional fabrication processes for large rocket engine structures. Various forms of selectively net-shape PM have been around for thirty years or so. However, it is only recently that major applications have been pursued for rocket engine hardware fabricated in the United States. The method employs sacrificial metallic tooling (HIP capsule and shaped inserts), which is removed from the part after HIP consolidation of the powder, by selective acid dissolution. Full exploitation of net-shape PM requires innovative approaches in both component design and materials and processing details. The benefits include: uniform and homogeneous microstructure with no porosity, irrespective of component shape and size; elimination of welds and the associated quality and life limitations; removal of traditional producibility constraints on design freedom, such as forgeability and machinability, and scale-up to very large, monolithic parts, limited only by the size of existing HIP furnaces. Net-shape PM HIP also enables fabrication of complex configurations providing additional, unique functionalities. The progress made in these areas will be described. Then critical aspects of the technology that still require significant further development and maturation will be discussed from the perspective of an engine systems builder and end-user of the technology.

Bampton, Cliff; Goodin, Wes; VanDaam, Tom; Creeger, Gordon; James, Steve

2005-01-01

58

Explosive-powder compaction system  

Microsoft Academic Search

Sandia National Laboratories has developed a pressure-control system and a test fixture to study the behavior of explosive materials during compaction. Both the pressure-control system and the test fixture are self-contained and portable. Explosive materials are compacted in a bridged header charge holder assembly by means of a test fixture and a pneumatic cylinder arrangement. Forces are measured with load

A. P. Montoya; M. L. Reichenbach

1981-01-01

59

Niobium-Alloyed high speed steel by powder metallurgy  

NASA Astrophysics Data System (ADS)

A philosophy for the use of strong carbide formers like niobium in high speed steels is described. It follows the concept of independently optimizing the compositions of the matrix (for maximum secondary hardening potential) and the volume fraction of the blocky carbides (for protection against abrasive wear). Normally, the two are interdependent through the action of the solidification equilibria, but separate control becomes possible when the blocky carbides are formed by a strong carbide former such as niobium. During normal ingot solidification, such strong carbide formers would produce very large primary carbides. This can be avoided by atomization and powder metallurgical processing. In this way, a steel has been produced whose matrix composition is similar to that of AISI M2, and whose primary carbides are all of NbC type. Its composition is 1.3C, 2W, 3Mo, 1.6V, 3.2Nb (wt pct). Because of its high stability, NbC is a much more effective obstacle to grain growth than the normal high speed steel carbides, and this allows substantially higher austenitization temperatures to be used. Despite its leaner composition, the Nb-alloyed steel matches the cutting performance of AISI M2, and its secondary hardening seems to be more persistent at high temperatures.

Karagöz, S.; Fischmeister, H. F.

1988-06-01

60

Niobium-alloyed high speed steel by powder metallurgy  

SciTech Connect

A philosophy for the use of strong carbide formers like niobium in high speed steels is described. It follows the concept of independently optimizing the compositions of the matrix (for maximum secondary hardening potential) and the volume fraction of the blocky carbides (for protection against abrasive wear). Normally, the two are interdependent through the action of the solidification equilibria, but separate control becomes possible when the blocky carbides are formed by a strong carbide former such as niobium. During normal ingot solidification, such strong carbide formers would produce very large primary carbides. This can be avoided by atomization and powder metallurgical processing. In this way, a steel has been produced whose matrix composition is similar to that of AISI M2, and whose primary carbides are all of NbC type. Its composition is 1.3C, 2W, 3Mo, 1.6V, 3.2Nb (wt pct). Because of its high stability, NbC is a much more effective obstacle to grain growth than the normal high speed steel carbides, and this allows substantially higher austenitization temperatures to be used. Despite its leaner composition, the Nb-alloyed steel matches the cutting performance of AISI M2, and its secondary hardening seems to be more persistent at high temperatures.

Karagoz, S.; Fischmeister, H.F.

1988-06-01

61

Fabrication and characterization of americium, neptunium and curium bearing MOX fuels obtained by powder metallurgy process  

NASA Astrophysics Data System (ADS)

MOX fuel pellets containing up to 1.4 wt% of Minor Actinides (MA), i.e. Am, Np and Cm, were fabricated to demonstrate the technical feasibility of powder metallurgy process involving, pelletizing and sintering in controlled atmosphere. The compounds were then characterized using XRD, SEM and EDX/EPMA. Dense pellets were obtained which closed porosity mean size is equal to 7 ?m. The results indicate the formation of (U, Pu)O 2 solid solution. However, microstructure contains some isolated UO 2 grains. The distribution of Am and Cm appears to be homogeneous whereas Np was found to be clustered at some locations.

Lebreton, Florent; Prieur, Damien; Jankowiak, Aurélien; Tribet, Magaly; Leorier, Caroline; Delahaye, Thibaud; Donnet, Louis; Dehaudt, Philippe

2012-01-01

62

Dose and Dose Risk Caused by Natural Phenomena - Proposed Powder Metallurgy Core Manufacturing Facility  

SciTech Connect

The offsite radiological effects from high velocity straight winds, tornadoes, and earthquakes have been estimated for a proposed facility for manufacturing enriched uranium fuel cores by powder metallurgy. Projected doses range up to 30 mrem/event to the maximum offsite individual for high winds and up to 85 mrem/event for very severe earthquakes. Even under conservative assumptions on meteorological conditions, the maximum offsite dose would be about 20 per cent of the DOE limit for accidents involving enriched uranium storage facilities. The total dose risk is low and is dominated by the risk from earthquakes. This report discusses this test.

Holmes, W.G.

2001-08-16

63

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

SciTech Connect

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.

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

64

1985 Annual Powder Metallurgy Conference, San Francisco, CA, July 14-17, 1985, Proceedings  

SciTech Connect

Among the P/M technology topics discussed are the dynamic degassing of metal powders, atomization gas selection, the rapid solidification of aluminum, design and fabrication of near net shape metal mirrors, phase distributions during the sintering of high speed steel powders, the impact strength and fatigue properties of a copper-infiltrated P/M steel, heavy metal alloys containing 30 to 90 percent tungsten, the interface in Mo-W composite compacts, and the manufacture and consolidation of superalloy powders. Also discussed are the isothermal forging of HIP-processed superalloys and titanium alloys, the role of powder morphology in dynamic compaction, aluminum flake-filled conductive plastics for EMI shielding and thermal conductivity, and the development status of liquid phase sintering.

Sanderow, H.I.; Giebelhausen, W.L.; Kulkarni, K.M.

1986-01-01

65

The stress-corrosion cracking behavior of high-strength aluminum powder metallurgy alloys  

NASA Astrophysics Data System (ADS)

The susceptibility to stress-corrosion cracking (SCC) of rapidly solidified (RS) aluminum powder metallurgy (P/M) alloys 7090 and 7091, mechanically alloyed aluminum P/M alloy IN* 9052, and ingot metallurgy (I/M) alloys of similar compositions was compared using bolt-loaded double cantilever beam specimens. In addition, the effects of aging, grain size, grain boundary segregation, pre-exposure embrittlement, and loading mode on the SCC of 7091 were independently assessed. Finally, the data generated were used to elucidate the mechanisms of SCC in the three P/M alloys. The IN 9052 had the lowest SCC susceptibility of all alloys tested in the peak-strength condition, although no SCC was observed in the two RS alloys in the overaged condition. The susceptibility of the RS alloys was greater in the underaged than the peak-aged temper. We detected no significant differences in susceptibility of 7091 with grain sizes varying from 2 to 300 ?m. Most of the crack advance during SCC of 7091 was by hydrogen embrittlement (HE). Furthermore, both RS alloys were found to be susceptible to preexposure embrittlement—also indicative of HE. The P/M alloys were less susceptible to SCC than the I/M alloys in all but one test.

Pickens, J. R.; Christodoulou, L.

1987-01-01

66

Crack Formation in Powder Metallurgy Carbon Nanotube (CNT)/Al Composites During Post Heat-Treatment  

NASA Astrophysics Data System (ADS)

After the post heat-treatment (PHT) process of powder metallurgy carbon nanotubes (CNT)/Al composites, micro-cracks were observed in the composites, leading to greatly degraded mechanical properties. To understand and suppress the crack formation, an in situ observation of CNT/Al composites was performed at elevated temperatures. PHT was also applied to various bulk pure Al and CNT/Al composites fabricated under different processes. It was observed that the composites consolidated by hot-extrusion might form micro-cracks, but those consolidated by spark plasma sintering (SPS) showed no crack after PHT. A high-temperature SPS process before hot-extrusion was effective to prevent crack formation. The release of residual stress in severe plastic deformed (SPD) materials was responsible for the cracking phenomena during the PHT process. Furthermore, a good particle bonding was essential and effective to suppress cracks for SPD materials in the PHT process.

Chen, Biao; Imai, Hisashi; Li, Shufeng; Jia, Lei; Umeda, Junko; Kondoh, Katsuyoshi

2014-12-01

67

A powder metallurgy austenitic stainless steel for application at very low temperatures  

E-print Network

The Large Hadron Collider to be built at CERN will require 1232 superconducting dipole magnets operating at 1.9 K. By virtue of their mechanical properties, weldability and improved austenite stability, nitrogen enriched austenitic stainless steels have been chosen as the material for several of the structural components of these magnets. Powder Metallurgy (PM) could represent an attractive production technique for components of complex shape for which dimension tolerances, dimensional stability, weldability are key issues during fabrication, and mechanical properties, ductility and leak tightness have to be guaranteed during operation. PM Hot Isostatic Pressed test plates and prototype components of 316LN-type grade have been produced by Santasalo Powdermet Oy. They have been fully characterized and mechanically tested down to 4.2 K at CERN. The fine grained structure, the absence of residual stresses, the full isotropy of mechanical properties associated to the low level of Prior Particle Boundaries oxides ...

Sgobba, Stefano; Liimatainen, J; Kumpula, M

2000-01-01

68

Particles into 410L Stainless Steel by a Powder Metallurgy Route  

NASA Astrophysics Data System (ADS)

Addition of yttria to steels has been proposed for the fabrication of oxide-dispersion-strengthened materials for nuclear power applications. We have investigated materials prepared from 12 Cr martensitic stainless steel, AISI 410L, produced by powder metallurgy. Materials were produced with and without yttria addition, and two different sizes of yttria were used, 0.9 µm and 50 nm. Tensile and mini-creep tests were performed to determine mechanical properties. Optical microscopy, SEM, TEM, and EDX analysis were used to investigate the microstructures and deformation mechanisms and to obtain information about non-metallic inclusion particles. SiO2, MnS, and Y2Si2O7 inclusion particles were observed. An SiO2 and Y2O3 interaction was seen to have occurred during the ball milling, which impaired the final mechanical properties. Small-angle neutron scattering experiments showed that the matrix chemistry prevented effective dissolution of the yttria.

Zeybek, A.; Barroso, S. Pirfo; Chong, K. B.; Edwards, L.; Fitzpatrick, M. E.

2014-06-01

69

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

SciTech Connect

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 measurements were also made over a temperature range of 50 to 300C since workpiece temperatures can attain levels this high during the machining operation. The thermal conductivity was measured using an apparatus having a design based on the comparative method. The experimentally determined thermal conductivities were modeled by mathematical models found in the technical literature and modified for the present study. The thermal conductivity of this material increases with increasing relative density and temperature; it is also dependent on the matrix structure for a given porosity.

Agapiou, J.S. (General Motors Technical Center, Warren, MI (United States)); DeVries, M.F. (Univ. of Wisconsin, Madison (United States))

1989-05-01

70

Micro-mechanical modelling of powder compaction  

NASA Astrophysics Data System (ADS)

This paper compares critically a trio of models of the compaction of granular materials in processes of industrial interest. The simplest model assumes an isotropic material with a spheroidal yield surface in principal stress space. The shape of this yield surface is constant but the size is a simple function of the volume strain. The other two models attempt to capture the anisotropic nature of compaction by assuming initially spherical granules that are deformable. One anisotropic model (kinematic) assumes an affine deformation of the centres of the spheres and gives relatively poor quantitative predictions. The other anisotropic model (static) assumes a simple approximation for the values of the contact forces and can be made to give adequate simulations of the compaction of at least some granular materials. Comparison with previously published experimental results shows that at least for some powders the history of anisotropic compaction is carried, not in the overall deformation, but in the maximum force seen by the contacts. Another important new result is that for the case of proportional loading the results of the isotropic model and the static model are in close, but not perfect agreement.

Henderson, R. J.; Chandler, H. W.; Akisanya, A. R.; Chandler, C. M.; Nixon, S. A.

2001-04-01

71

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

PubMed

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

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

2015-04-01

72

Characterization and mechanical properties of ultrahigh boron steels produced by powder metallurgy  

SciTech Connect

The present work is part of an investigation into the use of rapid solidification and powder metallurgy techniques to obtain iron-boron alloys with good mechanical properties. Two Fe-B binary alloys and two ultrahigh boron tool steels were gas atomized and consolidated by hot isostatic pressing (HIP) at temperatures ranging from 700 C to 1,100 C to have a fine microstructure. Optimum properties were achieved for the binary alloys at low consolidation temperatures, since the solidification microstructure from the original powders is eliminated and, at the same time, fine microstructures and low porosity are obtained in the alloys. At high temperatures and low strain rates, three of the four alloys exhibited low stress exponents, but only the Fe-2.2 pct B alloy showed tensile elongations higher than 100 pct. At low temperatures, only the Fe-2.2 pct B alloy deformed plastically. This alloy showed values of tensile elongation and ultimate tensile strength that were strongly dependent on testing and consolidation temperatures.

Jimenez, J.A.; Gonzalez-Doncel, G.; Ruano, O.A. [Centro Nacional de Investigaciones Metalurgicas, Madrid (Spain)

1996-07-01

73

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

Microsoft Academic Search

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

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

2001-01-01

74

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

NASA Astrophysics Data System (ADS)

An investigation was undertaken 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 and 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 for achieving equivalent fusion welding success similar to that seen in wrought titanium produced via the Kroll process.

Muth, T. R.; Yamamoto, Y.; Frederick, D. A.; Contescu, C. I.; Chen, W.; Lim, Y. C.; Peter, W. H.; Feng, Z.

2013-05-01

75

Strength and microstructure of powder metallurgy processed restacked Cu-Nb microcomposites  

NASA Astrophysics Data System (ADS)

Powder metallurgy (PM) was used to fabricate Cu-Nb microcomposites both at the laboratory and intermediate industrial scales. Ultimate tensile strengths (UTSs) of 1.6 and 1.035 GPa were obtained for the laboratory-and intermediate-scale composites, respectively. Filament morphology and the microstructure of various microcomposites were examined with transmission electron microscopy (TEM), scanning electron microscopy (SEM), and optical microscopy. In the early stages of the fabrication process, a plain strain condition causes the Nb fibers to attain a ribbonlike shape, but in the later stages, an axially symmetric flow prevails. Beyond the Nb filament thickness of 5 to 10 nm, the overall areal reduction was observed to occur without any significant reduction in the Nb filament thickness. Effects of heat treatment and the extent of spheroidization at different temperatures were studied. Contributions of various strengthening mechanisms on PM-processed Cu-Nb composites were analyzed. Work hardening, high strength of Nb filaments, and dispersion-type hardening were the dominant factors. Our strengthening model, which involves a superposition of the different contributions, agreed with our measurements.

Pourrahimi, S.; Nayeb-Hashemi, H.; Foner, S.

1992-02-01

76

Characterization of the carbides and the martensite phase in powder-metallurgy high-speed steel  

SciTech Connect

A microstructural characterization of the powder-metallurgy high-speed-steel S390 Microclean was performed based on an elemental distribution of the carbide phase as well as crystallographic analyses. The results showed that there were two types of carbides present: vanadium-rich carbides, which were not chemically homogeneous and exhibited a tungsten-enriched or tungsten-depleted central area; and chemically homogeneous tungsten-rich M{sub 6}C-type carbides. Despite the possibility of chemical inhomogenities, the crystallographic orientation of each of the carbides was shown to be uniform. Using electron backscatter diffraction the vanadium-rich carbides were determined to be either cubic VC or hexagonal V{sub 6}C{sub 5}, while the tungsten-rich carbides were M{sub 6}C. The electron backscatter diffraction results were also verified using X-ray diffraction. Several electron backscatter diffraction pattern maps were acquired in order to define the fraction of each carbide phase as well as the amount of martensite phase. The fraction of martensite was estimated using band-contrast images, while the fraction of carbides was calculated using the crystallographic data.

Godec, Matjaz, E-mail: matjaz.godec@imt.si [Institute of Metals and Technology, Lepi pot 11, 1000 Ljubljana (Slovenia); Batic, Barbara Setina; Mandrino, Djordje; Nagode, Ales; Leskovsek, Vojteh [Institute of Metals and Technology, Lepi pot 11, 1000 Ljubljana (Slovenia); Skapin, Sreco D. [Jozef Stefan Institute, Jamova 39, 1000 Ljubljana (Slovenia); Jenko, Monika [Institute of Metals and Technology, Lepi pot 11, 1000 Ljubljana (Slovenia)

2010-04-15

77

Characterisation of titanium-titanium boride composites processed by powder metallurgy techniques  

SciTech Connect

In this work, a detailed characterisation of titanium-titanium boride composites processed by three powder metallurgy techniques, namely, hot isostatic pressing, spark plasma sintering and vacuum sintering, was conducted. Two composites with different volume percents of titanium boride reinforcement were used for the investigation. One was titanium with 20% titanium boride, and the other was titanium with 40% titanium boride (by volume). Characterisation was performed using X-ray diffraction, electron probe micro analysis - energy dispersive spectroscopy and wavelength dispersive spectroscopy, image analysis and scanning electron microscopy. The characterisation results confirm the completion of the titanium boride reaction. The results reveal the presence of titanium boride reinforcement in different morphologies such as needle-shaped whiskers, short agglomerated whiskers and fine plates. The paper also discusses how mechanical properties such as microhardness, elastic modulus and Poisson's ratio are influenced by the processing techniques as well as the volume fraction of the titanium boride reinforcement. - Highlights: Black-Right-Pointing-Pointer Ti-TiB composites were processed by HIP, SPS and vacuum sintering. Black-Right-Pointing-Pointer The completion of Ti-TiB{sub 2} reaction was confirmed by XRD, SEM and EPMA studies. Black-Right-Pointing-Pointer Hardness and elastic properties of Ti-TiB composites were discussed. Black-Right-Pointing-Pointer Processing techniques were compared with respect to their microstructure.

Selva Kumar, M., E-mail: sel_mcet@yahoo.co.in [Department of Mechanical Engineering, Dr. Mahalingam College of Engineering and Technology, Pollachi-642003 (India); Chandrasekar, P.; Chandramohan, P. [School of Engineering, Professional Group of Institutions, Coimbatore-641662 (India)] [School of Engineering, Professional Group of Institutions, Coimbatore-641662 (India); Mohanraj, M. [Department of Mechanical Engineering, Info Institute of Engineering, Coimbatore-641107 (India)] [Department of Mechanical Engineering, Info Institute of Engineering, Coimbatore-641107 (India)

2012-11-15

78

Development and Processing of Novel Aluminum Powder Metallurgy Materials for Heat Sink Applications  

NASA Astrophysics Data System (ADS)

The objective of this research was to design aluminum powder metallurgy (PM) alloys and processing strategies that yielded sintered products with thermal properties that rivaled those of the cast and wrought aluminum alloys traditionally employed in heat sink manufacturing. Research has emphasized PM alloys within the Al-Mg-Sn system. In one sub-theme of research, the general processing response of each PM alloy was investigated through a combination of sintering trials, sintered density measurements, and microstructural assessments. In the second, the thermal properties of sintered products were studied in detail. Thermal conductivity was first determined using a calculated approach through discrete measurements of specific heat capacity, thermal diffusivity, and density and subsequently verified using a transient plane source technique on larger specimens. Experimental PM alloys achieved >99 pct theoretical density and exhibited thermal conductivity that ranged from 179 to 225 W/m K. Thermal performance was largely dominated by the amount of magnesium present within the aluminum grains and, in turn, bulk alloy chemistry. Data confirmed that the novel PM alloys were highly competitive with even the most advanced heat sink materials such as wrought 6063 and 6061.

Smith, L. J. B.; Corbin, S. F.; Hexemer, R. L.; Donaldson, I. W.; Bishop, Donald Paul

2014-02-01

79

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

NASA Astrophysics Data System (ADS)

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.

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

2014-08-01

80

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

NASA Astrophysics Data System (ADS)

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.

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

2014-07-01

81

Precipitation in cold-rolled Al–Sc–Zr and Al–Mn–Sc–Zr alloys prepared by powder metallurgy  

SciTech Connect

The effects of cold-rolling on thermal, mechanical and electrical properties, microstructure and recrystallization behaviour of the AlScZr and AlMnScZr alloys prepared by powder metallurgy were studied. The powder was produced by atomising in argon with 1% oxygen and then consolidated by hot extrusion at 350 °C. The electrical resistometry and microhardness together with differential scanning calorimetry measurements were compared with microstructure development observed by transmission and scanning electron microscopy, X-ray diffraction and electron backscatter diffraction. Fine (sub)grain structure developed and fine coherent Al{sub 3}Sc and/or Al{sub 3}(Sc,Zr) particles precipitated during extrusion at 350 °C in the alloys studied. Additional precipitation of the Al{sub 3}Sc and/or Al{sub 3}(Sc,Zr) particles and/or their coarsening was slightly facilitated by the previous cold rolling. The presence of Sc,Zr-containing particles has a significant antirecrystallization effect that prevents recrystallization at temperatures minimally up to 420 °C. The precipitation of the Al{sub 6}Mn- and/or Al{sub 6}(Mn,Fe) particles of a size ? 1.0 ?m at subgrain boundaries has also an essential antirecrystallization effect and totally suppresses recrystallization during 32 h long annealing at 550 °C. The texture development of the alloys seems to be affected by high solid solution strengthening by Mn. The precipitation of the Mn-containing alloy is highly enhanced by a cold rolling. The apparent activation energy of the Al{sub 3}Sc particles formation and/or coarsening and that of the Al{sub 6}Mn and/or Al{sub 6}(Mn,Fe) particle precipitation in the powder and in the compacted alloys were determined. The cold deformation has no effect on the apparent activation energy values of the Al{sub 3}Sc-phase and the Al{sub 6}Mn-phase precipitation. - Highlights: • The Mn, Sc and Zr additions to Al totally suppresses recrystallization at 550 °C. • The Sc,Zr-containing particle precipitation is slightly facilitated by cold rolling. • The Mn-containing particle precipitation is highly enhanced by cold rolling. • Cold rolling has no effect on activation energy of the Al{sub 3}Sc and Al{sub 6}Mn precipitation. • The texture development is affected by high solid solution strengthening by Mn.

Vlach, M., E-mail: martin.vlach@mff.cuni.cz [Charles University in Prague, Faculty of Mathematics and Physics, Ke Karlovu 3, CZ-121 16 Prague (Czech Republic); Stulikova, I.; Smola, B.; Kekule, T.; Kudrnova, H.; Danis, S. [Charles University in Prague, Faculty of Mathematics and Physics, Ke Karlovu 3, CZ-121 16 Prague (Czech Republic); Gemma, R. [King Abdullah University of Science and Technology (KAUST), Physical Sciences and Engineering Division, 23955-6900 Thuwal (Saudi Arabia); Ocenasek, V. [SVÚM a.s., Podnikatelská 565, CZ-190 11 Prague (Czech Republic); Malek, J. [Czech Technical University in Prague, Faculty of Mechanical Engineering, CZ-120 00 Prague (Czech Republic); Tanprayoon, D.; Neubert, V. [Institut für Materialprüfung und Werkstofftechnik, Freiberger Strasse 1, D-38678 Clausthal-Zellerfeld (Germany)

2013-12-15

82

Thermal Conductivity of Powder Aggregates and Porous Compacts  

NASA Astrophysics Data System (ADS)

A new equation for calculating the thermal conductivity of metal powder aggregates and sintered metal powder compacts is proposed. In this equation, the effective conductivity of the powder system is a function of the conductivity of the fully dense material, the porosity of the system, and the tap porosity of the starting powder. The new equation is applicable to powder systems, from the tap porosity to zero porosity, as well as to consolidated powders. The proposed equation has been experimentally validated by fitting to data from other authors. The results confirm a good agreement with theoretical predictions.

Montes, J. M.; Cuevas, F. G.; Cintas, J.; Muñoz, S.

2012-12-01

83

Deformation behavior of powder metallurgy Ni/sub 3/Al-Hf-B  

SciTech Connect

Boron-doped Ni/sub 3/Al-Hf processed by powder metallurgy technology exhibits superplastic behavior within certain strain rates of isothermal tension and compression. A fine, equiaxed grain size provided the optimum conditions. In this investigation, that grain size was 6 ..mu..m in as-extruded bar stock. The strain rate dependence of flow stress in tensile testing at 950 to 1150/sup 0/C confirmed the limitations for hot working as opposed to cold working. As in other products, the P/M product shows intergranular fracture and limited ductility above 800/sup 0/C under conventional strain rates. However, the results on the P/M product exhibit superplasticity (>100%) in tensile testing at strain rates below 10/sup -4//s. These results provided the opportunity for fabrication by hot isothermal forging. In two different press operations, isothermal forging of small cylinders cut from as-extruded bar stock revealed no peripheral cracking via 60% compression tests at strain rates of 0.5 and 0.1/min at 1100/sup 0/C. In some tests, the cylinders were compressed without cracking at a strain rate of 2 x 10/sup -3//s, one order of magnitude faster than the optimum strain rate in tensile testing. Isothermal forging of a prototype turbine disk was demonstrated by compression of the same size cylinders in a closed die at 1100/sup 0/C and strain rate of 0.5/min. The excellent surface and precise detail of the contours that can be obtained with P/M Ni/sub 3/Al-Hf-B, in this simple forming operation, are noteworthy. Even though isothermal forging is possible at a strain rate as high as 1.0/min at 1100/sup 0/C, both forging sources prefer a strain rate of 0.5/min for overall performance on a commercial-scale press.

Sikka, V.K.; Loria, E.A.

1986-01-01

84

Shock Compaction of Exchange-Coupled Nanocomposite Magnetic Powders  

NASA Astrophysics Data System (ADS)

Shock compaction was used to consolidate exchange-coupled R2Fe14B/?-Fe (R=Nd, Pr) hard/soft phase nanocomposite powders using a three-capsule plate-impact gas-gun loading system. Design of the consolidation fixture, densification conditions, and starting powder properties allowed control of the final density and microstructure of the shock-compacted samples. Highly dense compacts (˜99% of full density) with minimal interparticle melted/re-solidified zones and free from macrocracks were obtained under optimum consolidation conditions, in which case a laminar microstructure of the ribbon-shaped powders was observed. TEM characterization revealed complete retention of the nanostructure of the hard and soft phases, which grain sizes were within 20-25 nm in the final shock-compacted composite magnets. Retention of nanostructure ensured exchange coupling between the hard and soft phases, resulting in magnetic properties in the shock consolidated compacts similar to those of starting powders.

Jin, Z. Q.; Chen, K. H.; Li, J.; Zeng, H.; Liu, P.; Wang, Z. L.; Thadhani, N. N.

2004-07-01

85

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

NASA Astrophysics Data System (ADS)

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 calculated porosity content at various stages. Microstructural study has been carried out to compare observed porosity with the theoretically calculated porosity. X-ray diffraction studies of these alloys revealed presence of only ferrite as product phase. Various soft magnetic properties such as resistivity, coercivity, maximum flux density (at 350 G magnetic field), retentivity and total magnetic losses were also evaluated and reported. These alloys were made by hot forging using two different kinds of dies, e.g. flat die and channel die. It was observed that the flat-die forged alloys had more porosity than the channel-die forged alloys. Addition of alloying elements such as P, Cr and Si increased the resistivity of Fe. The higher the alloying addition, the higher is the alloy's resistivity. Fe-0.7P-0.7Cr-1Si alloy showed a resistivity as high as 44.1 ?? cm. Coercivity values of the alloys ranged from 1.0 to 2.2 Oe. Addition of Si and P helped in reducing the coercivity values of the alloys. The higher the Si, P content, the lower were the coercivity values observed. Combined addition of P and Si helped in reducing the coercivity values significantly, for example Fe-0.7P-0.7Cr-1Si alloy showed coercivity value approximately 1.0 Oe. It was observed in this investigation that maximum flux densities of the alloys were linearly related with their porosity levels. Total magnetic losses of these alloys varied from 6.0 to 7.8 W/kg. The total magnetic loss of Fe-0.7P-0.7Cr-1Si alloy was the lowest (6.0 W/kg) owing to its highest resistivity combined with its lowest coercivity amongst the alloys developed in the present investigation. Alloys developed in this investigation were capable of hot/cold working to very thin gage of sheet (0.5 mm thickness). These alloys could find their possible application in manufacturing of transformer core.

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

86

Preparation of Cu and Fly Ash Composite by Powder Metallurgy Technique  

SciTech Connect

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.

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

87

Preparation of Cu and Fly Ash Composite by Powder Metallurgy Technique  

NASA Astrophysics Data System (ADS)

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° 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.

Chew, P. Y.; Zahi, S.; You, A. H.; Lim, P. S.; Ng, M. C.

2011-03-01

88

Phase Transformation Behavior of Porous TiNi Alloys Produced by Powder Metallurgy Using Magnesium as a Space Holder  

NASA Astrophysics Data System (ADS)

Porous TiNi alloys with porosities in the range of 51 to 73 pct were prepared successfully applying a new powder metallurgy fabrication route in which magnesium was used as a space holder, resulting in either single austenite phase or a mixture of austenite and martensite phases dictated by the composition of the starting powders, but entirely free from secondary brittle intermetallics, oxides, nitrides, and carbonitrides. Since transformation temperatures are very sensitive to composition, deformation, and oxidation, for the first time, transformation temperatures of porous TiNi alloys were investigated using chemically homogeneous specimens in as-sintered and aged conditions eliminating secondary phase, contamination, and deformation effects. It was found that the porosity content of the foams has no influence on the phase transformation temperatures both in as-sintered and aged conditions, while deformation, oxidation, and aging treatment are severely influential.

Aydo?mu?, Tarik; Bor, Elif Tarhan; Bor, ?akir

2011-09-01

89

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

NASA Astrophysics Data System (ADS)

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 in amplitude and phase of the detected signal [1-5]. The crack existence at points in high stress regions of a group of green (unsintered) sprockets was evaluated through frequency scans. The results were validated by independent destructive cross-sectioning of the sprockets following sintering and polishing. Examination of the sectioned sprockets under a microscope at the locations where signal changes was used for correlation with the PTR signals. Statistical analysis confirmed the capabilities of the method to detect the presence of hairline cracks (~5 - 10 ?m size) with excellent sensitivity (91%) and good accuracy (78%) and specificity (61%). This measurement technique and the associated statistical analysis can be used as a simple and reliable on-line inspection methodology of industrial powder metallurgy manufactured steel products for non-destructive quality and feedback control of the parts forming process.

Tolev, J.; Mandelis, A.

2010-03-01

90

Modern developments in powder metallurgy; Proceedings of the International Powder Metallurgy Conference, Orlando, FL, June 5-10, 1988. Volumes 18, 19, 20, and 21  

SciTech Connect

Topics discussed include hot isostatic pressing, powder forging, metal injection molding, modeling of consolidation processes, liquid-phase sintering, novel P/M technology, innovation in tooling, soft magnetic materials, and superconductivity and shielding. Attention is given to the processing and properties of carbides, new tungsten alloys, refractory alloys, tool steels and cutting materials, spray-formed aluminum alloys, copper base and bearing alloys, P/M titanium, and plasma processing. Consideration is also given to powder-production mechanical processes, P/M composite materials, intermetallic compounds, high-temperature nickel-base materials, rapidly solidified materials, and the structure and properties of ferrous alloys. Additional topics include the fatigue properties of P/M materials, improved material properties, engineering properties via sintering, the generation and the effects of sintering atmospheres, improved dynamic properties in P/M parts, nonequilibrium P/M processing, Japan's progress in ferrous P/M ceramics, high-porosity materials, and process control and simulation.

Gummeson, P.U.; Gustafson, D.A.

1988-01-01

91

A New Multifunctional ? Ti Alloy Produced via Powder Metallurgy for Biomedical Applications  

NASA Astrophysics Data System (ADS)

Recent studies have revealed remarkable properties in ?-Ti alloys, including low elastic modulus, high strength and superelasticity. The unique properties and potentials in engineering and biomedical applications have invoked many physicists, material scientists and metallurgists to study its phenomenon. The requirements of these alloys in biomedical applications restrict the usage of toxic or allergic elements in the alloy design. Only a few alloying elements are suitable for developing non-toxic ? titanium alloys such as Nb, Ta and Zr. In this study a press-and-sinter process was used to consolidate the elemental powder mixture of Ti-Nb-Ta-Zr. Solid state sintering studies were established to investigate the effect of various green densities, sintering temperatures (i.e. 1650 °C - 1700 °C) and sintering atmosphere (i.e. Argon and Vacuum). PM near net shape process of showed a pathway to obtained a near dense part at sintered density of 97 % with compaction pressure of 707 MPa at 1700°C. Majority of the sintered Ti-23Nb-0.7Ta-2Zr (at.%) alloy's structure is ?- austenite (bcc).

Goh, F. C. W.; Hodgson, M. A.; Cao, P.

92

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

Microsoft Academic Search

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.

S Gorsse; J. P Chaminade; Y Le Petitcorps

1998-01-01

93

The most important tendencies in the development of powder metallurgy. II. Progress in the area of development of new materials (review)  

Microsoft Academic Search

The last decade has been characterized by progress in the area of development of new types of powder metallurgy materials including constructional, tribotechnical, composite, dispersion strengthened, fiber reinforced, tool, magnetic, corrosion-resistant, ceramic, aluminum- and titanium-base, and others. The volume of their use has been broadened in agricultural machinery, the machine tool industry, the automobile industry, the instrument industry, microelectronics, atomic

I. M. Fedorchenko

1989-01-01

94

Effects of Thermocapillary Forces during Welding of 316L-Type Wrought, Cast and Powder Metallurgy Austenitic Stainless Steels  

E-print Network

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 covers, for which fabrication by welding, casting or Powder Metallurgy (PM) was considered, are dished-heads equipped with a number of protruding nozzles for the passage of the different cryogenic lines. Structural materials and welds must retain high strength and toughness at cryogenic temperature. AISI 316L-type austenitic stainless steel grades have been selected because of their mechanical properties, ductility, weldability and stability of the austenitic phase against low-temperature spontaneous martensitic transformation. 316LN is chosen for the fabrication of the end covers, while the interconnection components to be welded on the protrud...

Sgobba, Stefano; 10.1016/S0924-0136(03)00373-X

2003-01-01

95

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)

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.

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

2012-07-01

96

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

PubMed

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

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

2003-01-01

97

1985 Annual Powder Metallurgy Conference, San Francisco, CA, July 14-17, 1985, Proceedings  

Microsoft Academic Search

Among the P\\/M technology topics discussed are the dynamic degassing of metal powders, atomization gas selection, the rapid solidification of aluminum, design and fabrication of near net shape metal mirrors, phase distributions during the sintering of high speed steel powders, the impact strength and fatigue properties of a copper-infiltrated P\\/M steel, heavy metal alloys containing 30 to 90 percent tungsten,

H. I. Sanderow; W. L. Giebelhausen; K. M. Kulkarni

1986-01-01

98

Compact, Non-Pneumatic Rock-Powder Samplers  

NASA Technical Reports Server (NTRS)

Tool bits that automatically collect powdered rock, permafrost, or other hard material generated in repeated hammering action have been invented. The present invention pertains to the special case in which it is desired to collect samples in powder form for analysis by x-ray diffraction and possibly other techniques. The present invention eliminates the need for both the mechanical collection equipment and the crushing chamber and the pneumatic collection equipment of prior approaches, so that it becomes possible to make the overall sample-acquisition apparatus more compact.

Sherrit, Stewart; Bar-Cohen, Yoseph; Badescu, Mircea; Bao, Xiaoqi; Chang, Zensheu; Jones, Christopher; Aldrich, Jack

2008-01-01

99

Characterization of uniaxial compaction in spray dried ceramic powders  

NASA Astrophysics Data System (ADS)

A model spray dried alumina powder system was studied with systematically varied binder content (2, 3, 4 and 5 wt%) and binder glass transition temperature (Tg). The Tg of the poly(vinyl alcohol) binder was adjusted between -32°C and +35°C by equilibration at five relative humidities. Compaction curves were constructed and dimensional changes on ejection were measured for all twenty compositions in uniaxial compaction at stresses from ˜6 MPa to ˜175 MPa. Compositions with low Tg during compaction resulted in the highest achievable densities and green strengths. However, green strength increased and achievable green density decreased with increasing binder content. Expansion on ejection were found to be dominated by the instantaneous axial springback (˜5--8%). Radial springback was less than ˜1% and the time-dependent relaxation was generally less than 0.5%. A technique was developed with which the effect of sample size on the compaction curve was calculated. The force opposing compaction due to friction at the die wall and the intrinsic compaction curve of the material were calculated based on two measured compaction curves. With these two characteristics known, it became possible to predict compaction curves of the powder for different sample sizes. Calculated compaction curves calculated correlated to measured compaction curves with R2 > 0.99. Additionally, a method was developed in which granule strength and intergranular bond strength during compaction was calculated. In a series of pellets pressed to a wide range of pressures, granule deformation and adhesion varied greatly between samples. Green strengths were measured by diametral compression and the fracture surfaces analyzed to determine the relative amounts of intergranular and intragranular fracture. A quadratic relationship was found between the overall green strength of the sample and the fracture mode. This curve was deconvoluted to the unique pair of linear functions that describe the intergranular bond strength and the intragranular strength throughout the compaction cycle. The 100% intergranular fracture, little or no consolidation has occurred, and the value of the intragranular strength line is a measure of the free granule strength. The free granule strength measured by this technique results in values much lower than the often-reported granule yield point measurement.

Carneim, Robert David

100

Kinetic Analysis of Solid-State Formation of Mg2Si by Powder Metallurgy Process  

NASA Astrophysics Data System (ADS)

The synthesis kinetics of Mg2Si intermetallic compounds (IMC) from the elemental mixture of Mg-Si powders was studied by using differential thermal analysis (DTA). The exothermic peaks were at 818 K, which indicated the synthesis reaction of 2Mg+Si ? Mg2Si. The synthesis kinetics of Mg2Si was evaluated by the Ozawa method and KAS method. The activation energy of Mg2Si was calculated as 376.0 kJ/mol by using the data from DTA curves. The bulky materials of Mg-Mg2Si composite were prepared through solid-state reaction by using SPS consolidation process. From the results of XRD and SEM-EDS analysis, it was known that Mg and Si powders never react completely at low temperatures of 813 K and 833 K, and the suitable temperature of solid-state synthesis by SPS should be about 853 K.

Sun, Bin; Li, Shufeng; Imai, Hisashi; Umeda, Junko; Kondoh, Katsuyoshi

101

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

Microsoft Academic Search

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

P Grootenhuis; R W Powell; R P Tye

1952-01-01

102

Stresses set up in the working parts of die sets during the pressing of metal powders  

Microsoft Academic Search

The powder compaction process constitutes an important link in the full technological cycle employed in the production of parts by the powder metallurgy technique. Although powder compaction has already received much attention in the literature [1-9, etc.] and considerable progress has been made in investigations of this process, more i-vestigational work is necessary if a clear understanding is to be

I. M. Fedorchenko; R. A. Kovynev; O. F. Polukhin

1970-01-01

103

The role of heat treatment on wear behavior of powder metallurgy low alloy steels  

Microsoft Academic Search

The influence of manufacturing parameters such as compacting pressure, heat treatment and microstructure on the static and dynamic properties of Fe–1.75 Ni–1.5 Cu–0.5 Mo–0.6 C was investigated. Wear and fatigue tests were carried out on reciprocate wearing and tension compression mode, respectively. The results show that delamination wear mechanism of sintered steel is similar to that of conventional wrought or

H Khorsand; S. M Habibi; H Yoozbashizadea; K Janghorban; S. M. S Reihani; H Rahmani Seraji; M Ashtari

2002-01-01

104

A small-angle X-ray scattering study of powder compaction  

Microsoft Academic Search

This work demonstrated a novel and potentially important application of two-dimensional small-angle X-ray scattering (2D-SAXS) to investigate powder compaction. SAXS from powder compacts of three materials commonly used for pharmaceutical tabletting exhibited azimuthal variations, with stronger intensity in the direction of the applied compaction force, relative to the transverse direction. This implied that compaction of a (macroscopic) powder could also

Peter R. Laity; Ruth E. Cameron

2008-01-01

105

Integration algorithms of elastoplasticity for ceramic powder compaction  

E-print Network

Inelastic deformation of ceramic powders (and of a broad class of rock-like and granular materials), can be described with the yield function proposed by Bigoni and Piccolroaz (2004, Yield criteria for quasibrittle and frictional materials. Int. J. Solids and Structures, 41, 2855-2878). This yield function is not defined outside the yield locus, so that 'gradient-based' integration algorithms of elastoplasticity cannot be directly employed. Therefore, we propose two ad hoc algorithms: (i.) an explicit integration scheme based on a forward Euler technique with a 'centre-of-mass' return correction and (ii.) an implicit integration scheme based on a 'cutoff-substepping' return algorithm. Iso-error maps and comparisons of the results provided by the two algorithms with two exact solutions (the compaction of a ceramic powder against a rigid spherical cup and the expansion of a thick spherical shell made up of a green body), show that both the proposed algorithms perform correctly and accurately.

M. Penasa; A. Piccolroaz; L. Argani; D. Bigoni

2014-04-24

106

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

Microsoft Academic Search

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

Wenhai Wang

2007-01-01

107

Oxidation and the Effects of High Temperature Exposures on Notched Fatigue Life of an Advanced Powder Metallurgy Disk Superalloy  

NASA Technical Reports Server (NTRS)

Oxidation and the effects of high temperature exposures on notched fatigue life were considered for a powder metallurgy processed supersolvus heat-treated ME3 disk superalloy. The isothermal static oxidation response at 704 C, 760 C, and 815 C was consistent with other chromia forming nickel-based superalloys: a TiO2-Cr2O3 external oxide formed with a branched Al2O3 internal subscale that extended into a recrystallized - dissolution layer. These surface changes can potentially impact disk durability, making layer growth rates important. Growth of the external scales and dissolution layers followed a cubic rate law, while Al2O3 subscales followed a parabolic rate law. Cr- rich M23C6 carbides at the grain boundaries dissolved to help sustain Cr2O3 growth to depths about 12 times thicker than the scale. The effect of prior exposures was examined through notched low cycle fatigue tests performed to failure in air at 704 C. Prior exposures led to pronounced debits of up to 99 % in fatigue life, where fatigue life decreased inversely with exposure time. Exposures that produced roughly equivalent 1 m thick external scales at the various isotherms showed statistically equivalent fatigue lives, establishing that surface damage drives fatigue debit, not exposure temperature. Fractographic evaluation indicated the failure mode for the pre-exposed specimens involved surface crack initiations that shifted with exposure from predominately single intergranular initiations with transgranular propagation to multi-initiations from the cracked external oxide with intergranular propagation. Weakened grain boundaries at the surface resulting from the M23C6 carbide dissolution are partially responsible for the intergranular cracking. Removing the scale and subscale while leaving a layer where M23C6 carbides were dissolved did not lead to a significant fatigue life improvement, however, also removing the M23C6 carbide dissolution layer led to nearly full recovery of life, with a transgranular initiation typical to that observed in unexposed specimens.

Sudbrack, Chantal K.; Draper, Susan L.; Gorman, Timothy T.; Telesman, Jack; Gab, Timothy P.; Hull, David R.

2012-01-01

108

Processing and properties of powder metallurgy Ni/sub 3/Al-Cr-Zr-B for use in oxidizing environments  

SciTech Connect

The addition of Cr to B-doped Ni/sub 3/Al in small ingots used for alloy development alleviates dynamic embrittlement, as exemplified by low tensile elongation and intergranular fracture, upon testing in air at 600/sup 0/C. Powder metallurgy (PM) technology is advantageous to properties due to improved microstructure from rapid solidification, and its effectiveness was studied in the up-scale production of four heats of this intermetallic compound with 8 Cr, 0.8 or 1.8 Zr, and 0.02 B (wt %). Sheet derived from a cold-rolling and annealing sequence on extruded product had a satisfactory level of ductility in tensile tests conducted in air within the critical 400 to 800/sup 0/C range. The processing parameters for hot workability of the PM product were established via a number of different strain rate tensils tests in air at temperatures up to 1100/sup 0/C. Superplastic behavior presented the opportunity for fabrication of a forged shape by hot isothermal forging. Preliminary forging of cylinders cut from the extruded bars revealed no peripheral cracking in 60% compression tests at strain rates of 0.1 to 0.5/min at 1100/sup 0/C. Successful isothermal forging of a prototype turbine disk directly from extruded bar stock in a closed die at 1100/sup 0/C and strain rate of 0.5/min was demonstrated, and the microstructure and mechanical properties were at least equal to those of PM sheet and bar products. 12 figs., 5 tabs.

Sikka, V.K.; Liu, C.T.; Loria, E.A.

1986-10-01

109

Sintering stress and microstructure in ceramic powder compacts  

SciTech Connect

The behavior of the sintering stress and microstructure during sintering is studied under various thermal and physical conditions. Specifically, the study includes sintering under isothermal or constant heating rate conditions; and altering the starting compact structure by pre-coarsening to increase the particle size, or by compaction to increase the starting density. Loading dilatometry is used to measure the ratio of the densification strain rate to the creep strain rate and the continuous shrinkage history of the systems. The data show that the ratio of the densification to the creep strain rate is remarkably constant within a wide temperature range for densification, from the earliest stages of densification to at least the onset of the final stage. As a consequence, the sintering stress, which is proportional to the strain rate ratio, is nearly independent of sintered density or of temperature. Analysis leads to a simple method for determining the simultaneous densification strain rate over the creep strain rate ratio. A rigorous densification strain rate equation is derived for a model system. The constant sintering stress allows progress on formulating a sintering equation to predict the densification behavior of powder compacts. Analysis of dilatometry data from compacts sintered at various heating rates, and of numerical computations, indicate the need to include separate coarsening processes with different activation energies. The same model is used to describe the differences in pore spacing evolution between pre-coarsened and as-received systems.

Chu, May-Ying (Lawrence Berkeley Lab., CA (USA) California Univ., Berkeley, CA (USA). Dept. of Materials Science and Mineral Engineering)

1990-08-01

110

Compaction of amorphous aluminum alloy powder by direct extrusion and equal channel angular extrusion  

Microsoft Academic Search

Al89Gd7Ni3Fe1 alloy powder produced by gas atomization was consolidated using equal channel angular extrusion (ECAE) and direct extrusion. The powder particle size was below 30?m and the as-received powder was ?70–80% amorphous. ECAE compaction of loose powder was conducted at 200°C. The microstructure of the compacted material was studied after different levels of ECAE deformation, which allowed analysis of the

O. N. Senkov; S. V. Senkova; J. M. Scott; D. B. Miracle

2005-01-01

111

A compact high-resolution X-ray powder diffractometer  

PubMed Central

A new powder diffractometer operating in transmission mode is described. It can work as a rapid very compact instrument or as a high-resolution instrument, and the sample preparation is simplified. The incident beam optics create pure Cu K?1 radiation, giving rise to peak widths of ?0.1° in 2? in compact form with a sample-to-detector minimum radius of 55?mm, reducing to peak widths of <0.05° in high-resolution mode by increasing the detector radius to 240?mm. The resolution of the diffractometer is shown to be governed by a complex mixture of angular divergence, sample size, diffraction effects and the dimensions of the detector pixels. The data can be collected instantaneously, which combined with trivial sample preparation and no sample alignment, makes it a suitable method for very rapid phase identification. As the detector is moved further from the sample, the angular step from the pixel dimension is reduced and the resolution improves significantly for very detailed studies, including structure determination and analysis of the microstructure. The advantage of this geometry is that the resolution of the diffractometer can be calculated precisely and the instrumental artefacts can be analysed easily without a sample present. The performance is demonstrated with LaB6 and paracetamol, and a critical appraisal of the uncertainties in the measurements is presented. The instantaneous data collection offers possibilities in dynamic experiments. PMID:24282331

Fewster, Paul F.; Trout, David R. D.

2013-01-01

112

In situ study of the ? phase decomposition process in a Cu-Al-Ni shape memory alloy processed by powder metallurgy  

NASA Astrophysics Data System (ADS)

The precipitation of the stable phases in Cu-Al-Ni shape memory alloys (SMA) limits the maximum using temperature since the decomposition of ? phase degrades very quickly the martensitic transformation. In this paper, the precipitation processes of the metastable ? phase during heating in a Cu-14.37 Al-4.2 Ni (wt. %) SMA processed by powder metallurgy have been studied by Differential Scanning Calorimetry (D.S.C.) and in situ neutron powder diffraction. The pro-eutectoid ?_1; precipitation and the eutectoid decomposition has been observed during heating, followed by the posterior dissolution at higher temperature. The transformation temperatures have been determined by D.S.C. The Rietveld analysis performed on the neutron diffraction spectra allows to determine the volume fraction of the different precipitated phases and their evolution during heating. The activation energy of the primary ?_1, precipitation has been determined.

Recarte, V.; Pérez-Landazabal, J. I.; Campo, J.; Pérez-Saez, R. B.; No, M. L.; San Juan, J.

2003-10-01

113

Nanotechnology in the metallurgy of steel  

Microsoft Academic Search

Progress in ferrous metallurgy in the second half of the twentieth century was associated with rapid replacement of the basic production systems, in a kind of technical revolution. Large-capacity converter and electrosmelting systems were organized, along with ladle treatment of the steel, vacuum treatment, continuous casting, coke-free metallurgy, powder metallurgy, and hydroextrusion. Thus, effective new approaches to the production of

S. V. Kolpakov; V. A. Parshin; A. N. Chekhovoi

2007-01-01

114

Compaction and strain hardening of metal powders and their mixtures when pressed  

Microsoft Academic Search

The compaction of carbonyl nickel powders, nickel-based mixtures, and iron, aluminum, and magnesium powders in cylindrical\\u000a molds is experimentally studied, the billet height being continuously recorded in a testing machine. The theory of plasticity\\u000a for powder bodies is used to analyze the strain hardening of the matrix forming a powder body in pressing. It is established\\u000a that shear yield stress

A. K. Radchenko; M. S. Koval’chenko; D. N. Brodnikovskii

2009-01-01

115

Simulation of high velocity compaction of powder in a rubber mould with characterization of silicone rubber and titanium powder using a modified split Hopkinson set-up  

Microsoft Academic Search

The paper introduces a method for characterization of silicone rubber and titanium powder in high velocity compaction using the split Hopkinson set-up. The impact test data has been used to estimate parameters in constitutive models for rubber and powder. A finite element study has been performed with different geometrical design of the high velocity compaction of titanium powder against an

Hans-Åke Häggblad; Matthias Hockauf; Mikael Eriksson; Carina Berggren

2005-01-01

116

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)

The effects of alloy chemistry and particulate morphology on consolidation behavior and consolidated product properties in rapid solidification processed, powder-metallurgical Al-3Li-1.5Cu-1Mg-0.5Co-0.2Zr and Al-4.4Cu-1.5Mg-Fe-Ni-0.2Zr extrusions and forgings were studied. Microstructures and mechanical properties of both alloys are largely unaffected by particulate production method (vacuum atomization, ultrasonic atomization, or twin-roller quenching) and by particulate solidification rates between 1000 and 100,000 K/s. Consolidation processing by canning, cold compaction, degassing, and hot extrusion is sufficient to yield mechanical properties in the non-Li-containing alloy extrusions which are similar to those of 7075-Al, but ductilities and fracture toughnesses are inferior owing to poor interparticle bonding caused by lack of a vacuum-hot-pressing step during consolidation. Mechanical properties of extrusions are superior to those of forgings owing to the stronger textures produced by the more severe hot working during extrusion. The effects on mechanical properties of dispersoid size and volume fraction, substructural refinement, solid solution strengthening by Mg, and precipitate size and distribution are elucidated for both alloy types.

Meschter, P. J.; Lederich, R. J.; Oneal, J. E.; Pao, P. S.

1985-01-01

117

A discrete finite element modelling and measurements for powder compaction  

NASA Astrophysics Data System (ADS)

An experimental investigation into friction between powder and a target surface together with numerical modelling of compaction and friction processes at a micro-scale are presented in this paper. The experimental work explores friction mechanisms by using an extended sliding plate apparatus operating at low load while sliding over a long distance. Tests were conducted for copper and 316 steel with variation in loads, surface finish and its orientation. The behaviours of the static and dynamic friction were identified highlighting the important influence of particle size, particle shape, material response and surface topography. The results also highlighted that under light loading the friction coefficient remains at a level lower than that derived from experiments on equipment having a wider dynamic range and this is attributed to the enhanced sensitivity of the measurement equipment. The results also suggest that friction variation with sliding distance is a consequence of damage, rather than presentation of an uncontaminated target sliding surface. The complete experimental cycle was modelled numerically using a combined discrete and finite element scheme enabling exploration of mechanisms that are defined at the particle level. Using compaction as the starting point, a number of simulation factors and process parameters were investigated. Comparisons were made with previously published work, showing reasonable agreement and the simulations were then used to explore the process response to the range of particle scale factors. Models comprising regular packing of round particles exhibited stiff response with high initial density. Models with random packing were explored and were found to reflect trends that are more closely aligned with experimental observation, including rearrangement, followed by compaction under a regime of elastic then plastic deformation. Numerical modelling of the compaction stage was extended to account for the shearing stage of the extended sliding plate experiment. This allowed micro-scale simulations of the friction mechanisms seen within the experimental programme. The frictional response with similar stress level in the normal direction as reported for the experiment was first emulated and explored and qualitative agreement was achieved showing a similar pattern. The factors identified from the experiments were investigated on smooth and rough surfaces highlighting each effect. It was confirmed that the rough surface clearly leads to higher friction coefficient since it accounts for both plain friction and topographical effects and the average stress distribution increased against the restraining die wall when the rough surface was introduced for the model with round regular packing of particles. Random packed models again showed a better reflection of the experimental conditions. A wider distribution of stress was observed because of the further rearrangements. Interlocking was observed for the models with irregularly shaped particles on a rough surface, which led to an increase in normal stress on the top punch. This would lead to dilation in the case where a punch was force level controlled as for the experiment.

Choi, J. L.; Gethin, D. T.

2009-04-01

118

Cold compaction study of Armstrong Process Ti-6Al-4V powders  

SciTech Connect

This work investigates the cold compaction behavior of Ti-6Al-4V powders produced by Armstrong Process . As-received as well as milled powders were characterized and these powders were uniaxially die-pressed at designated pressures up to 690 MPa to form disk samples with different aspect ratios. Samples with high aspect ratio exhibited non-uniform density along the pressing axis and the density distribution is in consistent with the result predicted by finite element analysis. The linear regression analysis on the experimental density data can be used to predict density of compacts with different aspect ratios. In the studied pressure range, an empirical powder compaction equation represents the green density pressure relationship very well for both the as-received and 1-hr milled Armstrong Ti-6Al-4V powders.

Chen, Wei [ORNL; Yamamoto, Yukinori [ORNL; Peter, William H [ORNL; Gorti, Sarma B [ORNL; Sabau, Adrian S [ORNL; Clark, Michael B [ORNL; Nunn, Stephen D [ORNL; Kiggans, Jim [ORNL; Blue, Craig A [ORNL; Fuller, Brian [International Titanium Powder; Akhtar, Kamal [International Titanium Powder

2011-01-01

119

Effect of Lubrication on the Improvement of Uniformity in Uniaxial Powder Compaction  

Microsoft Academic Search

Density distribution in powder compact caused by frictional force at die wall has been estimated. The pressure transmission ratio lambda was defined for the estimation of the magnitude of frictional force occurrence on die wall. The density gradient alpha was also defined for the estimation of density distribution. The iron and pre-alloyed stainless steel powder were tested, and the performance

Yukinori Taniguchi; Kuniaki Dohda; Zhrgang Wang

2005-01-01

120

Effects of temperature on the mechanical properties of Ti6Al4V powder compacts prepared by magnetic pulse compaction  

Microsoft Academic Search

The effects of temperature (0–500°C) on the compressive strength, hardness, average relative density, and microstructure of\\u000a Ti6Al4V powder green compacts prepared by magnetic pulse compaction were investigated. The results show that with increasing\\u000a heating temperature, the compressive strength first increases and then decreases with the maximum value of 976.74 MPa at 400°C.\\u000a The average relative density and hardness constantly increase,

Min Li; Haiping Yu; Chunfeng Li

2010-01-01

121

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

PubMed

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

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

2014-06-01

122

Measuring internal temperature profiles in microwave-heated ceramic powder compacts  

SciTech Connect

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 temperature profiles of microwave-heated ceramic bodies. The authors will describe a method of non-perturbing, in-situ measurement of internal temperature profiles in microwave-heated ceramic powder compacts based on localized spinel-formation reactions within a sintering alumina compact.

Booske, J.H.; Cooper, R.F.; Binger, K.R. [Univ. of Wisconsin, Madison, WI (United States)

1998-12-31

123

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

SciTech Connect

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.

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

2013-07-15

124

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

Microsoft Academic Search

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

S. Sgobba; T. Daniellou

2003-01-01

125

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

NASA Astrophysics Data System (ADS)

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.

Wang, Wenhai

126

The biaxial loading response of powder aluminum at elevated temperature  

Microsoft Academic Search

Nuclear fuel can be fabricated using powder-metallurgy processes by compacting uranium-oxide powder with aluminum powder to\\u000a form a cermet and then extruding the cermet to form fuel tubes. This method of production allows greater control of uranium-oxide\\u000a particle size and distribution in the tube, making the production of fuel with greater concentrations of uranium oxide possible,\\u000a and thus decreasing the

T. O. Woods; D. G. Berghaus

1994-01-01

127

Surface Area, and Oxidation Effects on Nitridation Kinetics of Silicon Powder Compacts  

NASA Technical Reports Server (NTRS)

Commercially available silicon powders were wet-attrition-milled from 2 to 48 hr to achieve surface areas (SA's) ranging from 1.3 to 70 sq m/g. The surface area effects on the nitridation kinetics of silicon powder compacts were determined at 1250 or 1350 C for 4 hr. In addition, the influence of nitridation environment, and preoxidation on nitridation kinetics of a silicon powder of high surface area (approximately equals 63 sq m/g) was investigated. As the surface area increased, so did the percentage nitridation after 4 hr in N2 at 1250 or 1350 C. Silicon powders of high surface area (greater than 40 sq m/g) can be nitrided to greater than 70% at 1250 C in 4 hr. The nitridation kinetics of the high-surface-area powder compacts were significantly delayed by preoxidation treatment. Conversely, the nitridation environment had no significant influence on the nitridation kinetics of the same powder. Impurities present in the starting powder, and those accumulated during attrition milling, appeared to react with the silica layer on the surface of silicon particles to form a molten silicate layer, which provided a path for rapid diffusion of nitrogen and enhanced the nitridation kinetics of high surface area silicon powder.

Bhatt, R. T.; Palczer, A. R.

1998-01-01

128

The Influences of Carbon and Molybdenum on the Progress of Liquid Phase Sintering and the Microstructure of Boron-Containing Powder Metallurgy Steel  

NASA Astrophysics Data System (ADS)

Boron is an optimal alloying element for liquid phase sintering (LPS) of powder metallurgy (PM) Fe-based materials. However, the influences of various alloying elements on the progress of LPS are still undetermined. The aim of this study was to clarify the effects of carbon and molybdenum on the LPS and microstructure of boron-containing PM steel. The results showed that adding 0.5 wt pct C and 1.5 wt pct Mo, and particularly the former, promotes the LPS and increases the sintered density. With the addition of 0.5 wt pct C, liquid can be generated in two distinct regions, and the secondary liquid improves the densification. After 1523 K (1250 °C) sintering, the increases in sintered densities of Fe-0.4B, Fe-0.4B-1.5Mo, Fe-0.4B-0.5C, and Fe-0.4B-1.5Mo-0.5C steels were 0.33, 0.47, 0.56, and 0.64 g/cm3, respectively. Thermodynamic simulation also demonstrated that the increases in sintered densities were correlated with the liquid volumes formed at 1523 K (1250 °C). In conclusion, adding 0.5 wt pct C to B-containing PM steels facilitates the formation of a secondary liquid phase and higher liquid volume, resulting in better densification.

Wu, Ming-Wei

2015-01-01

129

Effect of inclusion size on the high cycle fatigue strength and failure mode of a high V alloyed powder metallurgy tool steel  

NASA Astrophysics Data System (ADS)

The fatigue strength of a high V alloyed powder metallurgy tool steel with two different inclusion size levels, tempered at different temperatures, was investigated by a series of high cycle fatigue tests. It was shown that brittle inclusions with large sizes above 30 ?m prompted the occurrence of subsurface crack initiation and the reduction in fatigue strength. The fracture toughness and the stress amplitude both exerted a significant influence on the fish-eye size. A larger fish-eye area would form in the sample with a higher fracture toughness subjected to a lower stress amplitude. The stress intensity factor of the inclusion was found to lie above a typical value of the threshold stress intensity factor of 4 MPa·m1/2. The fracture toughness of the sample with a hardness above HRC 56 could be estimated by the mean value of the stress intensity factor of the fish-eye. According to fractographic evaluation, the critical inclusion size can be calculated by linear fracture mechanics.

Yao, Jun; Qu, Xuan-hui; He, Xin-bo; Zhang, Lin

2012-07-01

130

Cold compaction of an aluminium\\/short fibre alumina powder composite  

Microsoft Academic Search

Al-20Si-3 Cu-1 Mg-0.3 Fe (wt%) rapidly solidified powder homogeneously mixed with 0, 5,10 and 20 vol % Saffil alumina fibres, was subjected to cold uni-axial, single-action die-compression with progressively increasing pressures up to ~ 400 MPa and intermediate relaxation. The powders with 0 and 20 vol % fibres were also compacted to this target pressure in single steps and the

J. H. Haar; J. Duszczyk

1992-01-01

131

Simulation of Aluminum Powder in Tube Compaction Using Equal Channel Angular Extrusion  

NASA Astrophysics Data System (ADS)

Aluminum powder in tube compaction with a 25 mm front plug through equal channel angular extrusion (ECAE) at room temperature was modeled using the finite element analysis package ABAQUS. The Gurson model was used in modeling this process. 2-D simulations in a 90° angle die showed better consolidation of powder near the inner edge of the die than the outer edge after one pass of ECAE but almost full densification occurs after two passes. The effect of hydrostatic pressure on densification of the powder was investigated by using two plugs varying in length dimension. The results obtained from the simulations were also compared with experiments conducted to compact aluminum powder with mean particle diameter of 45 ?m. Optical microscopy, microhardness test, and density measurements confirmed the simulations. The simulations were extended to powder compaction in a 60° and 120° angle die. It was found that one pass of ECAE is sufficient to consolidate the aluminum powder completely and uniformly in a 60° angle die, whereas the material is still porous in a 120° angle die.

Haghighi, Reza Derakhshandeh; Jahromi, Ahmad Jenabali; Jahromi, Behnam Esfandiar

2012-02-01

132

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

SciTech Connect

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.

Jonsen, P.; Haeggblad, H.-A. [Division of Solid Mechanics, Department of Applied Physics and Mechanical Engineering, Luleaa University of Technology, 971 87 Luleaa (Sweden)

2007-05-17

133

Continuum-based FEM modeling of ceramic powder compaction using a cap-plasticity constitutive model  

SciTech Connect

Common ceramic component manufacturing typically involves the processing of the raw materials in powder form. Granulated powder is formed into a green body of the desired size and shape by consolidation, often by simply pressing nominally dry powder. Ceramic powders are commonly pressed in steel dies or rubber bags with the aim of producing a near-net-shape green body for subsequent sintering. Density gradients in these compacts, introduced during the pressing operation, are often severe enough to cause distortions in the shape of the part during sintering due to nonuniform shrinkage. In such cases, green machining or diamond grinding operations may be needed to obtain the desired final shape and size part. In severe cases, nonuniform shrinkage may even cause fracture in the parts during sintering. Likewise, density gradients can result in green bodies that break during ejection from the die or that are too fragile to be handled during subsequent processing. Empirical relationships currently exist to describe powder compaction but provide little understanding of how to control die design or compaction parameters to minimize density gradients thereby forcing the designer to use expensive and time consuming trial and error procedures. For this reason, interest has grown in developing computational tools to address this problem (Aydin et al., 1996 and Coube, 1998). The goal of the present work was to develop a general continuum-based finite element model for ceramic powder compaction that can be used to aid and guide the design and pressing of ceramic powders. Such a model can be used to improve both part and die/bag pressing design, resulting in more efficient and cost effective ways to make better parts.

ARGUELLO JR.,JOSE G.; FOSSUM,ARLO F.; ZEUCH,DAVID H.; EWSUK,KEVIN G.

2000-01-25

134

The Reactive Stabilisation of Aluminum-Zinc-X Foams via the Formation of a Transient Liquid Phase Using the Powder Metallurgy Approach  

NASA Astrophysics Data System (ADS)

During the past few decades, aluminum foam research has focused on the improvement of properties. These properties include pore structure and process reproducibility. High energy absorption capacity, lightweight and high stiffness to weight ratio are some of the properties that make these foams desirable for a number of diverse applications. The use of a transient liquid phase and melting point depressant was studied in order to improve aluminum foam manufactured through the powder metallurgy process and to create reactive Stabilisation. The transient liquid phase reacts with aluminum and helps encapsulate higher levels of hydrogen, simultaneously reducing the difference between the melting point of the alloy and the gas release temperature of the blowing agent (TiH2). A large difference is known to adversely affect foam properties. The study of pure aluminum foam formation was undertaken to understand the basic foaming mechanisms related to crack formations under in-situ conditions. Elemental zinc powder at various concentrations (Al-10wt%Zn, Al-33wt%Zn and Al-50wt%Zn) was added to produce a transient liquid phase. Subsequently, an Al-12wt%Si pre-alloyed powder was added to the Al-Zn mixture in order to further reduce the melting point of the alloy and to increase the amount of transient liquid phase available (Al-3.59wtSi-9.6%Zn and Al-2.4wt%Si-9.7wt%Zn). The mechanical properties of each system at optimal foaming conditions were assessed and compared. It was determined that pure aluminum foam crack formation could be suppressed at higher heating rates, improving the structure through the nucleation of uniform pores. The Al-10wt%Zn foams generated superior pore properties, post maximum expansion stability and mechanical properties at lower temperatures, compared to pure aluminum. The Al-Si-Zn foams revealed remarkable stability and pore structure at very low temperatures (640 to 660°C). Overall, the Al-10wt%Zn and Al-3.59wt%Si-9.6wt%Zn foams offer superior properties compared to pure aluminum.

Lafrance, Maxime

135

Characterisation of the green machinability of AlN powder compacts  

Microsoft Academic Search

The aim of this work is to study the machinability of aluminium nitride green bodies obtained from dry pressing of spray-dried granules. The characterisation of the green machinability of ceramics is not easy. Indeed, to date, no conventional mechanical test able to represent the machining behaviour of green powder ceramic compacts. Therefore, the first target of this work is to

M. Desfontaines; Y. Jorand; M. Gonon; G. Fantozzi

2005-01-01

136

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

E-print Network

is very different from that of conventional heating (e.g., resistive, flame and induction). KnowledgeThermal behavior of supersolidus bronze powder compacts during heating by hollow cathode discharge were heated either by plasma or by a resistive furnace technique. The plasma heating was performed

dos Santos, C.A.

137

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

SciTech Connect

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.

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

2006-01-27

138

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

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.)

Not Available

1994-04-01

139

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

SciTech Connect

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.)

Not Available

1993-05-01

140

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

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)

NONE

1997-01-01

141

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

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.)

NONE

1995-02-01

142

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

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)

NONE

1995-12-01

143

Processing and Characterization of Cu-Al-Ni Shape Memory Alloy Strips Prepared from Elemental Powders via a Novel Powder Metallurgy Route  

NASA Astrophysics Data System (ADS)

In the present work, Cu-Al-Ni shape memory alloy strips were prepared successfully from premixed elemental Cu, Al, and Ni powders in the ratio 82:14:4 (wt pct) by a novel processing route consisting of preparing powder preforms, sintering, and unsheathed hot rolling of the sintered preforms. Subsequently, the hot rolled strips were homogenized. The as-rolled strips consisted of two phases— ? and ?'. A postconsolidation homogenization of the hot rolled strips was carried out at 1173 K (900 °C) for different time periods. It has been shown that a homogenization period of 4 hours was sufficient to achieve a single-phase material consisting of only martensitic phase. It also has been shown that the 4-hour homogenized and quenched Cu-Al-Ni shape memory alloy strips primarily consisted of self-accommodated ?' martensite plates, which are necessary for realizing shape memory effect (SME). The finished hot rolled Cu-Al-Ni strips had a fracture strength of 476 MPa, coupled with 2.5 pct elongation. The shape memory tests showed almost 100 pct recovery after 10 thermomechanical cycles in the hot rolled strips at 1 pct and 2 pct prestrain level.

Sharma, Mohit; Vajpai, Sanjay Kumar; Dube, Ravindra Kumar

2010-11-01

144

?TCP ceramic doped with dicalcium silicate for bone regeneration applications prepared by powder metallurgy method: in vitro and in vivo studies.  

PubMed

This study reports on the in vitro and in vivo behavior of ?-tricalcium phosphate (?TCP) and also ?TCP doped with either 1.5 or 3.0 wt % of dicalcium silicate (C2 S). The ceramics were successfully prepared by powder metallurgy method combined with homogenization and heat treatment procedures. All materials were composed of a single-phase, ?TCP in the case of a pure material, or solid solution of C2 S in ?TCP for the doped ?TCP, which were stable at room temperature. The ceramics were tested for bioactivity in simulated body fluid, cell culture medium containing adult mesenchymal stem cells of human origin, and in animals. Analytical scanning electron microscopy combined with chemical elemental analysis was used and Fourier transform infrared and conventional histology methods. The in vivo behavior of the ceramics matched the in vitro results, independently of the C2 S content in ?TCP. Carbonated hydroxyapatite (CHA) layer was formed on the surface and within the inner parts of the specimens in all cases. A fully mineralized new bone growing in direct contact with the implants was found under the in vivo conditions. The bioactivity and biocompatibility of the implants increased with the C2 S content in ?TCP. The C2 S doped ceramics also favoured a phase transformation of ?TCP into CHA, important for full implant integration during the natural bone healing processes. ?TCP ceramic doped with 3.0 wt % C2 S showed the best bioactive in vitro and in vivo properties of all the compositions and hence could be of interest in specific applications for bone restorative purposes. PMID:23225787

Velasquez, Pablo; Luklinska, Zofia B; Meseguer-Olmo, Luis; Mate-Sanchez de Val, Jose E; Delgado-Ruiz, Rafael A; Calvo-Guirado, Jose L; Ramirez-Fernandez, Ma P; de Aza, Piedad N

2013-07-01

145

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

NASA Astrophysics Data System (ADS)

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.

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

2013-06-01

146

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

SciTech Connect

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.

Yokota, S.H.

1992-12-01

147

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

E-print Network

TWO METHODS FOR CHARACTERIZING THE COMPACTION AND EJECTION BEHAVIOR OF METAL POWDERS IN A DIE A Thesis by RICHARD JAMES SAJDAK Submitted to the Graduate College of Texas A&M University in partial fulfillment of the requirement for the degree... of MASTER OF SCIENCE May 1969 Major Subject: Mechanical Engineering TNO METHODS FOR CHARACTERIZ1NG THE COMPACTION AND EJFCTION BEHAVIOR OF 1'1FTAL PONDERS IN A DIE A Thesis by RICHARD JAMES SAJDAK Approved a" to style and content by: airman...

Sajdak, Richard James

2012-06-07

148

Effect of Lubrication on the Improvement of Uniformity in Uniaxial Powder Compaction  

NASA Astrophysics Data System (ADS)

Density distribution in powder compact caused by frictional force at die wall has been estimated. The pressure transmission ratio ? was defined for the estimation of the magnitude of frictional force occurrence on die wall. The density gradient ? was also defined for the estimation of density distribution. The iron and pre-alloyed stainless steel powder were tested, and the performance of zinc stearate and paraffin wax applied as internal lubricant or die wall lubricant has been investigated in various conditions. The die wall lubrication becomes effective way to increase ? in comparison with the internal lubrication. Admixed lubricant prevents the occurrence of density distribution and uniform green compact is obtained in the critical amount of lubricant. Paraffin wax shows higher performance as a die wall lubricant compared with zinc stearate, and remarkable increase of lubrication effect is observed in the combination between zinc stearate as internal lubricant and paraffin wax as wall lubricant.

Taniguchi, Yukinori; Dohda, Kuniaki; Wang, Zhrgang

149

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

NASA Astrophysics Data System (ADS)

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, and varying impact velocity (up to 500 m/s) provided different levels of stress, strain, and kinetic energy. The IMACON 200 framing camera was used to observe the transient densification, deformation, and reaction states. AUTODYN 2D was used to simulate the densification and deformation process, and correlate with that observed by high-speed imaging. It was found that the reaction initiates after continued straining following densification of the powder compact, illustrating that neither the kinetic energy and nor the resulting projectile-anvil equilibrated stress are independently controlling the initiation of the intermetallic reaction. Characteristics of threshold conditions for impact-initiated reactions in the various Al-based intermetallic powder-mixture compacts will be presented.

Du, S. W.; Thadhani, N. N.

2009-12-01

150

Plutonium Metallurgy  

SciTech Connect

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.

Freibert, Franz J. [Los Alamos National Laboratory

2012-08-09

151

Influence of foreign particles on fatigue behavior of Ti-6Al-4V prealloyed powder compacts  

NASA Astrophysics Data System (ADS)

The effect of three types of contaminants on the fatigue life of prealloyed Plasma Rotating Electrode Process (PREP) Ti-6A1-4V hot isostatically pressed (HIP’d) powder compacts was studied. Ultraclean powder was seeded separately with SiO2, A12O3, and 316 stainless steel (SS) contaminants of 50 ?m, 150 ?, and 350 ?m nominal size, a total of nine conditions. Seeded compacts were fatigue tested at room temperature and the results were compared to those of an unseeded baseline compact. It was found that a substantial loss in fatigue life occurred even at the smallest seeded contaminants used in this work. Angular nonmetallic SiO2 and A12O3 contaminants were found to be more detrimental to fatigue strength than spherical metallic 316 SS contaminants of the same size range also indicating a shape effect. The loss of fatigue life suggests that at the high stress levels there is almost no crack initiation period and fatigue lives are controlled mainly by crack growth.

Schwenker, S. W.; Eylon, D.; Froes, F. H.

1986-02-01

152

Characterization techniques to validate models of density variations in pressed powder compacts  

SciTech Connect

Techniques for characterizing density gradients generated during typical powder compaction processes are reviewed and several are evaluated. The techniques reviewed are ultrasonic velocity measurements, laser ultrasonic velocity measurements, x-ray radiography, autoradiography, computer tomography (CT), magnetic resonance imaging (MRI), and simple image analysis of polished cross-sections. Experimental results are reported for all of these techniques except autoradiography, CT and MRI. The test specimens examined were right circular cylinders of a high length/diameter ratio (to ensure significant density variation) pressed from commercial spray-dried alumina powders. Although the density gradients could be detected with all four techniques, ultrasonic velocity measurements gave the best contour map of gradients and is therefore most suitable for model validation. On the other hand, it was concluded that x-ray radiography is preferable in situations where cost and/or number of samples are more important that high resolution.

Garino, T.; Mahoney, M.; Readey, M.; Ewsuk, K.; Gieske, J.; Stoker, G. [Sandia National Labs., Albuquerque, NM (United States); Min, S. [Sandia National Labs., Livermore, CA (United States)

1995-07-01

153

Effect of Particle Size on Microstructure and Cold Compaction of Gas-Atomized Hypereutectic Al-Si Alloy Powder  

NASA Astrophysics Data System (ADS)

The effect of particle size on the cold compaction behavior of rapidly solidified hypereutectic Al-27 wt pct Si alloy powder was studied by double action axial pressing at room temperature. The geometrical characteristics (morphology, size, shape, and distribution of Si reinforcing phase) and hardness of the powder as a function of the particle size were investigated. The result shows that finer powder particle size showed smaller primary Si particles and achieved a lower density at a given pressure. Whereas, the microhardness of Al matrix increases while the particle size decreases, which indicates that the supersaturation due to the high solidification rate increases the deformation resistance of the alloy powder. Furthermore, the geometrical characteristics of Si phases strongly depend on the particle size due to the suppressed growth of Si phases during atomization. This microstructural characteristic evidently affects the powder compactibility at high applied pressures.

Cai, Zhiyong; Wang, Richu; Peng, Chaoqun; Zhang, Chun

2014-12-01

154

Minimum Amount of Binder Removal Required during Solvent Debinding of Powder-Injection-Molded Compacts  

NASA Astrophysics Data System (ADS)

Unsatisfactory dimensional control, distortion, and defects are frequently observed in powder-injection-molded parts, particularly after the solvent and thermal-debinding processing steps. One of the reasons is that the amount of soluble binder removed during the first step, solvent debinding, is not great enough to form interconnected pores throughout the compact, particularly in the core region. Thus, blistering, cracking, and bubbles can form easily during the subsequent thermal debinding. To determine the minimum debinding fraction required for solvent debinding, at which point interconnected pore channels are formed at the center, modeling of the distribution of the remaining soluble binder in the compact was established. The actual distribution, which was obtained by measuring the binder content layer by layer with the soxhelt extraction method, is in good agreement with the model. The modeling, bubble test, and fluorescence dye-penetration analysis show that, regardless of the compact thickness, the minimum bulk debinding fraction needed is consistently approximately 59 pct, yielding a local debinding fraction of 37 pct and a porosity of 8.5 pct at the center. This porosity is close to the value at which pores in a sintered compact transform from open to closed at the beginning of the final stage of sintering.

Fan, Yang-Liang; Hwang, Kuen-Shyang; Wu, Shiau-Han; Liau, Yau-Ching

2009-04-01

155

Continuum-Based FEM Modeling of Ceramic Powder Compaction Using a Cap-Plasticity Constitutive Model  

SciTech Connect

Software has been developed and extended to allow finite element (FE) modeling of ceramic powder compaction using a cap-plasticity constitutive model. The underlying, general-purpose FE software can be used to model even the most complex three-dimensional (3D) geometries envisioned. Additionally, specialized software has been developed within this framework to address a general subclass of axisymmetric compacts that are common in industry. The expertise required to build the input deck, run the FE code, and post-process the results for this subclass of compacts is embedded within the specialized software. The user simply responds to a series of prompts, evaluates the quality of the FE mesh that is generated, and analyzes the graphical results that are produced. The specialized software allows users with little or no FE expertise to benefit from the tremendous power and insight that FE analysis can bring to the design cycle. The more general underlying software provides complete flexibility to model more complicated geometries and processes of interest to ceramic component manufacturers but requires significantly more user interaction and expertise.

ARGUELLO JR.,JOSE G.; FOSSUM,ARLO F.; ZEUCH,DAVID H.; EWSUK,KEVIN G.

2000-05-01

156

EXPLOSIVE COMPACTION OF CLAD GRAPHITE POWDERS AND OBTAINING OF COATINGS ON THEIR BASE  

SciTech Connect

In order to consolidate graphite based powders and in order to obtain coatings with density values near to the theoretical ones clad graphite powders of the C{sub graphite} - Ni (C{sub g} - Ni) compositions were explosively compacted under different loading conditions. Theoretical calculations revealed that for assessing the stress-deformed state of C{sub g} - Ni compositions and computing the normal and tangent stress components (when V{sub D} < C{sub longitudinal} and V{sub D} < C{sub transversal}) it is recommended to apply the dynamic problem's solution model while the pressure impulse P = f(x) is being uniformly spread with constant rate along the boundary of a semi-infinite elastic body. The results of our experiments showed that it is possible to obtain high dense coatings from C{sub g}-Ni compositions bonded by an intermediate layer to the substrate material. The structure and properties of the coatings depends on the intensity of the shock loading and temperature. The effect of the shock loading conditions (temperature, loading intensity) on the structure, properties and structure/properties relationships for the C{sub g} - Ni coatings are discussed.

A. B. PEIKRISHIVILI; ET AL

2000-11-01

157

Application of X-ray Microtomography and Image Processing to the Investigation of a Compacted Granular System  

E-print Network

to the pharmaceutical, food and powder metallurgy industries. In order to produce a uniform, high quality end productApplication of X-ray Microtomography and Image Processing to the Investigation of a Compacted disassembly approach [1], followed by magnetic reso- nance imaging (MRI) [2], scanning confocal microscopy [3

Elliott, James

158

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

PubMed

Abstract 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

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

2014-04-16

159

Continuum-based FEM modeling of ceramic powder compaction using a cap-plasticity constitutive model  

Microsoft Academic Search

Common ceramic component manufacturing typically involves the processing of the raw materials in powder form. Granulated powder is formed into a green body of the desired size and shape by consolidation, often by simply pressing nominally dry powder. Ceramic powders are commonly pressed in steel dies or rubber bags with the aim of producing a near-net-shape green body for subsequent

JOSE G. ARGUELLO JR; ARLO F. FOSSUM; DAVID H. ZEUCH; KEVIN G. EWSUK

2000-01-01

160

Effect of isothermal forging on microstructure and fatigue behavior of blended elemental Ti-6Al-4V powder compacts  

NASA Astrophysics Data System (ADS)

The effect of isothermal hot forging (IHF) on microstructure, pore closure, and tensile and fatigue properties of Ti-6A1-4V blended elemental cold pressed and sintered powder compacts was investigated. Two types of sponge fines were used: (a) high chloride produced by the Hunter sodium reduction process (HP) and (b) low chloride produced by the electrolytic process (EP). The as-sintered HP compacts were 99 pct dense while the EP compacts were only 92 pct dense. All sintered preforms were isothermally hot forged below the beta transus temperature and reached almost full density. The microstructure of the HP forged compacts consisted of fine equiaxed alpha, while the EP forged compacts exhibited a coarse lenticular alpha structure after 30 pct reduction and a partially recrystallized structure after 68 pct reduction. It was found that EP compacts forged to a 30 pct reduction exhibited a low fatigue limit of 172 MPa (25 ksi), since the lenticular alpha morphology and the residual porosity resulted in premature fatigue crack initiation. On the other hand, a higher fatigue strength of 485 MPa (70 ksi) was obtained for EP compacts forged to a 78 pct reduction due to the mixed equiaxed/lenticular alpha morphology as well as removal of stress concentration features such as interparticle pore interfaces.

Weiss, I.; Eylon, D.; Toaz, M. W.; Froes, F. H.

1986-03-01

161

Effect of isothermal forging on microstructure and fatigue behavior of blended elemental Ti-6Al-4V powder compacts  

SciTech Connect

The effect of isothermal hot forging (IHF) on microstructure, pore closure, and tensile and fatigue properties of Ti-6Al-4V blended elemental cold pressed and sintered powder compacts was investigated. Two types of sponge fines were used: (1) chloride produced by the Hunter sodium reduction process (HP) and (2) low chloride produced by the electrolytic process (EP). The as-sintered HP compacts were 99 pct dense while the EP compacts were only 92 pct dense. All sintered preforms were isothermally hot forged below the beta transus temperature and reacted almost full density. The microstructure of the HP forged compacts consisted of fine equiaxed alpha, while the EP forged compacts exhibited a coarse lenticular alpha structure after 30 pct reduction and a partially recrystallized structure after 68 pct reduction. It was found that EP compacts forged to a 30 pct reduction exhibited a low fatigue limit of 172 MPa (25 ksi), since the lenticular alpha morphology and the residual porosity resulted in premature fatigue crack initiation. On the other hand, a higher fatigue strength of 485 MPa (70 ksi) was obtained for EP compacts forged to a 78 pct reduction due to the mixed equiaxed/lenticular alpha morphology as well as removal of stress concentration features such as interparticle pore interfaces. 26 references.

Weiss, I.; Eylon, D.; Toaz, M.W.; Froes, F.H.

1986-03-01

162

Simulation of the compaction dynamics of Cu + Al 2 O 3 powder mixture under impulse hot pressing  

Microsoft Academic Search

The compaction dynamics of Cu + Al2O3 powder mixture under impulse hot pressing is simulated using a third-order dynamic system. The computer simulation has established\\u000a the time dependence of the force induced by mechanical interaction between the impact machine and a heated porous blank, time\\u000a variation in density, and root-mean-square strain rates and stresses in the matrix that forms the

M. S. Kovalchenko; T. P. Hrebenok; L. F. Ochkas

2011-01-01

163

On the applicability of the P-? and P-? models to describe the dynamic compaction response of highly heterogeneous powder mixtures  

NASA Astrophysics Data System (ADS)

The shock consolidation response of recently obtained data for a powder mixture of Ta + Bi2O3 with previously published results for mixtures of Ni + Al, Mo + Si, and Ti + Si are investigated within the context of the P-? and P-? models to determine the applicability of these models to highly heterogeneous powder mixtures. The mixtures were found to vary significantly in densification path and crush strength (pressures required to reach full density), and no one model offers the best fit for all the mixtures. The static spherical P-? model, which uses mechanical properties of the solid materials to predict the compaction response for the powder mixtures, was found to provide the greatest disagreement with experimental data. By modifying the yield parameter to reflect measured yield properties from quasi-static densification tests, better agreement between the model and experimental data was obtained. For the empirical fitting models, the ability of a model to separate compaction into elastic and plastic components had minimal influence on goodness of fit. Conversely, homogeneity in deformation of the constituent particles was found to promote model agreement, specifically for the Mo + Si and Ti + Si powder mixtures where dynamically recovered microstructures were available for inspection.

Fredenburg, D. A.; Thadhani, N. N.

2013-01-01

164

Degrees in Metallurgy and Materials  

E-print Network

Degrees in Metallurgy and Materials Course outline School of Metallurgy and Materials Materials us? Dr Alessandro Mottura Undergraduate Admissions Tutor for Metallurgy and Materials What difference will you make? #12;Degrees in Metallurgy and Materials Understanding the properties of new materials

Birmingham, University of

165

Equal channel angular extrusion compaction of semi-amorphous Al 85Ni 10Y 2.5La 2.5 alloy powder  

Microsoft Academic Search

Al85Ni10Y2.5La2.5 alloy powder produced by gas atomization was compacted using equal channel angular extrusion (ECAE). The powder particle size was below 40 ?m (?325 mesh grade), the powder was partially (?60%) amorphous and it contained intermetallic phases. Differential scanning calorimetry showed that crystallization of the amorphous phase starts at about 220°C by precipitation of Al-based f.c.c. particles and continues at

O. N Senkov; D. B Miracle; J. M Scott; S. V Senkova

2004-01-01

166

Metastable structures in metallurgy  

Microsoft Academic Search

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

David Turnbull

1981-01-01

167

Metallurgy and properties of plasma spray formed materials  

NASA Technical Reports Server (NTRS)

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.

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

1992-01-01

168

NON-MELT PROCESSING OF "LOW-COST", ARMSTRONG TITANIUM AND TITANIUM ALLOY POWDERS  

SciTech Connect

In the last decade, a considerable effort has been made to develop new methods for producing low cost titanium and titanium powders. The Armstrong process is a new method of producing titanium powder via reducing TiCl4 vapor in molten sodium. The process is scalable, and can be used to produce pre-alloyed powders. Non-melt processing and powder metallurgy approaches are economically viable with the commercially pure powders. In this investigation, several non-melt processing technologies, including vacuum hot pressing, extrusion, roll compaction, and forging techniques, will be evaluated using the Armstrong titanium powders. The metallurgical, chemical, and mechanical properties of the processed titanium samples will be discussed.

Peter, William H [ORNL; Blue, Craig A [ORNL; Clive, Scorey [Ametek, Inc.; Ernst, Bill [International Titanium Powder; McKernan, John [Ametek, Inc.; Kiggans, Jim [ORNL; Rivard, John D [ORNL; Yu, Dr. Charlie [Ametek, Inc.

2007-01-01

169

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

DOEpatents

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.

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

1991-08-27

170

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

DOEpatents

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.

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

1991-08-27

171

Piezochromic Phenomena of Nanometer Voids Formed by Mono-Dispersed Nanometer Powders Compacting Process  

PubMed Central

Piezochromism describes a tendency of certain materials changing colors when they are subjected to various pressure levels. It occurs particularly in some polymers or inorganic materials, such as in palladium complexes. However, piezochromism is generally believed to work at high pressure range of 0.1–10 GPa. This research work focused on unique piezochromism responses of the nanometer voids formed by the 5–20 nm inorganic ISOH nanometer powders. It was discovered that microstructures of the nanometer voids could change color at very low pressures of only 0.002–0.01 GPa; its sensitivity to pressure was increased by tens of times. It is believed that the uniform microstructures of nanometer powders contributed to the material's high sensitivity of piezochromic phenomena. One factor which quantum optical change caused by nanometer voids affected the quantum confinement effect; another is surface Plasmon Resonance of great difference dielectric property between conductive ITO powder and insulation hydroxide. PMID:24115999

Su, Lihong; Wan, Caixia; Zhou, Jianren; Wang, Yiguang; Wang, Liang; Ai, Yanling; Zhao, Xu

2013-01-01

172

Use of limestone powder during incorporation of Pb-containing cathode ray tube waste in self-compacting concrete.  

PubMed

For several decades, cathode ray tubes (CRTs) were the primary display component of televisions and computers. The CRT glass envelope contains sufficient levels of lead oxide (PbO) to be considered hazardous, and there is a need for effective methods of permanently encapsulating this material during waste disposal. We examined the effect of adding limestone powder (LS) on the fresh and cured properties of self-compacting concrete (SCC) mixtures containing waste CRT glass. The SCC mixtures were prepared using Type 1 Portland cement at a constant cement content of 600 kg/m(3) and a water-to-cement ratio (w/c) of 0.38. CRT glass waste cullet was blended with river sand in proportions of 20 or 40% by weight. To suppress potential viscosity effects limestone powder was added at levels of 5, 10, or 15% by weight. The slump flow time, slump flow diameter, V-funnel flow time, Marsh cone flow time, and setting time of the fresh concrete were tested, as well as the compressive strength and ultrasonic pulse velocity of the hardened concrete. Addition of limestone powder improved the fresh and hardened properties. Pb leaching levels from the cured concrete were within US EPA allowable limits. PMID:23892134

Sua-iam, Gritsada; Makul, Natt

2013-10-15

173

Influence of thermomechanical processing on low cycle fatigue of prealloyed Ti-6AI-4V powder compacts  

NASA Astrophysics Data System (ADS)

A wide range of microstructures was generated using various thermomechanical processing sequences in Ti-6A1-4V Rotating Electrode Process (REP) powder compacts of low contaminant content. Low cycle fatigue results were found to be superior to those in higher contaminant compacts tested in a previous program. All microstructural groups showed fatigue strengths equivalent to those found in wrought alloy, with the beta-annealed condition being lowest as expected. Alpha + beta work and solution treatment resulted in an excellent fatigue strength of 875 MN/m2 (127 ksi) at 105 cycles; 85 pct of the UTS. In the five conditions tested, the fatigue strength increased with increasing tensile strength, decreasing grain size, and increasing volume fraction of low aspect ratio primary alpha. Most crack initiation sites were observed at the specimen surface. Only alpha + beta worked and solution-treated material exhibited subsurface initiations, none of which was associated with any defect or with a lower fatigue life. Although compacts contained some tungsten particles, in no case were they associated with crack initiation sites, indicating that they were innocuous in the conditions evaluated.

Eylon, D.; Froes, F. H.; Heggie, D. G.; Blenkinsop, P. A.; Gardiner, R. W.

1983-12-01

174

Power metallurgy tool electrodes for electrical discharge machining  

Microsoft Academic Search

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

M. P. Samuel; P. K. Philip

1997-01-01

175

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

NASA Astrophysics Data System (ADS)

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.

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

2008-02-01

176

International Powder Metallurgy Conference September 4-8, 2002, Turkish Powder Metallurgy Association  

E-print Network

the diffusion distance between the different atoms. The fracturing of the welded particles impedes. During ball milling two essential processes occure: cold welding between the different particles and fracturing of the cold welded particles due to high energy collision [1]. The cold welding minimizes

Gubicza, Jenõ

177

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

E-print Network

ME 4210: Manufacturing Processes and Engineering Prof. J.S. Colton © GIT 2009 2 #12;Powder General Motors automotive engines Source: Courtesy of Zenith ME 4210: Manufacturing Processes Processes and Engineering Prof. J.S. Colton © GIT 2009 4 #12;Making Powder-Metallurgy PartsMaking Powder

Colton, Jonathan S.

178

Ris-M-2888 Metallurgy Department  

E-print Network

©KC^OOO-»9 å Risø-M-2888 Metallurgy Department Publications 1989 Risø National Laboratory, DK-4000 Roskilde, Denmark August 1990 #12;Metallurgy Department Publications 1989 Edited by A. Horsewell Risø of the Metallurgy Department during 1989 are listed. This list is divided into three sections asfollows

179

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

180

KV-tOOJHfe Metallurgy Department  

E-print Network

»KV-tOOJHfe RisB-R-547 Metallurgy Department Progress Report for the Period 1 January to 31 December 1986 Risø National Laboratory, DK-4000 Roskilde, Denmark April 1987 #12;Risø-R-547 METALLURGY.B. BiIde-Sørensen Abstract. The activities of the Metallurgy Department at Risø during 1986

181

Enery Efficient Press and Sinter of Titanium Powder for Low-Cost Components in Vehicle Applications  

SciTech Connect

This is the final technical report for the Department of Energy NETL project NT01931 Energy Efficient Press and Sinter of Titanium Powder for Low-Cost Components in Vehicle Applications. Titanium has been identified as one of the key materials with the required strength that can reduce the weight of automotive components and thereby reduce fuel consumption. Working with newly developed sources of titanium powder, Webster-Hoff will develop the processing technology to manufacture low cost vehicle components using the single press/single sinter techniques developed for iron based powder metallurgy today. Working with an automotive or truck manufacturer, Webster-Hoff will demonstrate the feasibility of manufacturing a press and sinter titanium component for a vehicle application. The project objective is two-fold, to develop the technology for manufacturing press and sinter titanium components, and to demonstrate the feasibility of producing a titanium component for a vehicle application. The lowest cost method for converting metal powder into a net shape part is the Powder Metallurgy Press and Sinter Process. The method involves compaction of the metal powder in a tool (usually a die and punches, upper and lower) at a high pressure (up to 60 TSI or 827 MPa) to form a green compact with the net shape of the final component. The powder in the green compact is held together by the compression bonds between the powder particles. The sinter process then converts the green compact to a metallurgically bonded net shape part through the process of solid state diffusion. The goal of this project is to expand the understanding and application of press and sinter technology to Titanium Powder applications, developing techniques to manufacture net shape Titanium components via the press and sinter process. In addition, working with a vehicle manufacturer, demonstrate the feasibility of producing a titanium component for a vehicle. This is not a research program, but rather a project to develop a process for press and sinter of net shape Titanium components. All of these project objectives have been successfully completed.

Thomas Zwitter; Phillip Nash; Xiaoyan Xu; Chadwick Johnson

2011-03-31

182

Applied fractal geometry and powder technology  

Microsoft Academic Search

Powder technology is important to many industries including mining, food processing, paint technology, powder metallurgy and space research. Applied fractal geometry is being used in these industries to describe and comprehend the complex interactions of many causes. The topics to be discussed in this review include, the study of important fractally structured pigments, the fractal structure of hazardous fumes, and

B. H. Kaye

1995-01-01

183

Metallurgy Department Progress Report for  

E-print Network

Risø National Laboratory, DK-4000 Roskilde, Denmark July 1981 #12;ERRATA SHEET FOR Rise-R-444 Line 21 33 PARTICIPATION IN INTERNATIONAL COLLABORATION 37 EDUCATION AND TRAINING 39 PUBLICATIONS 40 LECTURES or the nuclear progresses are continued in order to ensure up-to-date knowledge. In the Metallurgy Department

184

Analysis of powdered tungsten carbide hard-metal precursors and cemented compact tungsten carbides using laser-induced breakdown spectroscopy  

NASA Astrophysics Data System (ADS)

Laser-induced breakdown spectroscopy (LIBS) has been applied to the direct analysis of powdered tungsten carbide hard-metal precursors and cemented tungsten carbides. The aim of this work was to examine the possibility of quantitative determination of the niobium, titanium, tantalum and cobalt. The investigated samples were in the form of pellets, pressed with and without binder (powdered silver) and in the form of cemented tungsten carbides. The pellets were prepared by pressing the powdered material in a hydraulic press. Cemented tungsten carbides were embedded in resin for easier manipulation. Several lasers and detection systems were utilized. The Nd:YAG laser working at a basic wavelength of 1064 nm and fourth-harmonic frequency of 266 nm with a gated photomultiplier or ICCD detector HORIBA JY was used for the determination of niobium which was chosen as a model element. Different types of surrounding gases (air, He, Ar) were investigated for analysis. The ICCD detector DICAM PRO with Mechelle 7500 spectrometer with ArF laser (193 nm) and KrF laser (248 nm) were employed for the determination of niobium, titanium, tantalum and cobalt in samples under air atmosphere. Good calibration curves were obtained for Nb, Ti, and Ta (coefficients of determination r2 > 0.96). Acceptable calibration curves were acquired for the determination of cobalt (coefficient of determination r2 = 0.7994) but only for the cemented samples. In the case of powdered carbide precursors, the calibration for cobalt was found to be problematic.

Novotný, K.; Sta?ková, A.; Häkkänen, H.; Korppi-Tommola, J.; Otruba, V.; Kanický, V.

2007-12-01

185

Resistive and magnetoresistive properties of compacted CrO2 powders with different types of intergranular dielectric layers  

NASA Astrophysics Data System (ADS)

Resistive, magnetoresistive and magnetic properties of four types of pressed CrO2 powders synthesized from chromic anhydride by the hydrothermal method were investigated. The new synthesis method allowed controlling the thickness of dielectric shells. The powders consisted of rounded particles (?120 nm in dia.) or acicular crystals (?22.9 nm in dia. and 302 nm in length). The particles were covered with a surface dielectric shell of different thickness and type (e.g. ?-CrOOH oxyhydroxide or chromium oxide Cr2O3). The influence of the properties and the thickness of intergranular dielectric layers as well as the shape of CrO2 particles on the tunneling resistance and magnetoresistance (MR) of the pressed powders was studied. It was found that at low temperatures all the investigated samples displayed a nonmetallic temperature dependence of resistance and a giant negative MR. The maximal values of MR at T ? 5 K were found to be approx. 37% in relatively low magnetic fields (0.5 T). The MR decreased rapidly with increasing temperature (down to approx. 1% in 1 T at T ? 200 K). At low temperatures the powders with acicular particles exhibited a new type of MR hysteresis and nonmonotonous dependence of MR with increasing magnetic field. A nonmonotonous temperature dependence Hp(T), where Hp is the field in which the resistance is maximal, mismatch between the values of Hp and coercive force Hc, and the anisotropy of MR as a function of mutual orientation of transport current and magnetic field were observed.

Dalakova, N. V.; Belevtsev, B. I.; Beliayev, E. Yu.; Bludov, A. N.; Pashchenko, V. N.; Osmolovsky, M. G.; Osmolovskaya, O. M.

2012-12-01

186

Recent trends in extractive metallurgy  

NASA Astrophysics Data System (ADS)

Metallurgists and solution geochemists are joining forces to develop processes for extraction of metals from low-grade ores. The processes, which come under the name hydrometallurgy, include several new applications of solvent extraction techniques. Aqueous solutions are employed, leaching metals from ores, mine waste dumps, and even from deposits still in the ground. It was notable, for example, that Chemical and Engineering News (Feb. 8, 1982) recently featured the subject of hydrometallurgy in a special report. They noted that ‘recovering metals by use of aqueous solutions at relatively low temperatures increasingly is competing with dry, high-temperature pyrometallurgical methods.’ The relatively new techniques have caused a revolution, of sorts, in engineering programs of university metallurgy departments. The challenge of developing selective metal dissolution processes is drawing upon the best national talent in the fields of solution geochemistry and metallurgy.

Bell, Peter M.

187

Physical metallurgy of nickel aluminides  

Microsoft Academic Search

A description of the important physical metallurgy aspects of N13Al and NiAl encompassing structure, crystallographic defects, slip systems and phase stability has been presented in this\\u000a article. The microstructures generated in the two alloys by conventional as well as novel processing techniques have been\\u000a discussed. The effect of alloying additions on the microstructure has been enumerated. Besides description of the

G. K. Dey

2003-01-01

188

University of Cambridge Department of Materials Science & Metallurgy  

E-print Network

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

Cambridge, University of

189

Evaluation of surface and bulk characteristics of cellulose I powders in relation to compaction behavior and tablet properties.  

PubMed

The particle properties and solid-state characteristics of two celluloses, Avicel PH101 and cellulose obtained from the alga Cladophora sp., were evaluated and related to the compaction behavior and the properties of the tablets made from them. The surface area of the celluloses was measured at different levels of penetration capacity, ranging from external surface area of particles to molecular texture with Blaine permeametry, Kr-gasadsorption, and solid-state NMR. The important cellulose fibril surface area was best reflected by solid-state NMR, although for the Cladophora cellulose, Kr-gas adsorption also resulted in a surface area of the order of what has been suggested earlier on the basis of the cellulose fibril dimensions. The difference in fibril dimension and, thereby, the fibril surface area of the two celluloses was shown to be the primary factor in determining their properties and behavior. Properties such as the crystallinity and the tablet disintegration could be related to the fibril dimensions. The Cladophora cellulose resulted in rather strong compacts that still disintegrated rapidly. The irregular surface morphology of the particles and the fragmenting behavior of Cladophora probably contributed to the strength of the tablets. PMID:14677770

Gustafsson, Christina; Lennholm, Helena; Iversen, Tommy; Nyström, Christer

2003-11-01

190

Increased compactibility of acetames after roll compaction.  

PubMed

A common technique for manufacturing granules in a continuous way is the combination of roll compaction and subsequent milling. Roll compaction can considerably impact tableting performance of a material. The purpose of this study was to investigate the influence of roll compaction/dry granulation on the compaction behavior of acetames, a class of active pharmaceutical substances, which are mainly used for the treatment of central nervous diseases. Some representatives of acetames were roll compacted and then compressed into tablets. Compactibility of granules was compared with the compaction behavior of the directly compressed drug powders. In contrast to many other materials, the roll compaction step induced an increase in compactibility for all investigated acetames. Specific surface areas of the untreated and the roll compacted drugs were determined by nitrogen adsorption. The raise in compactibility observed was accompanied by an increase in specific surface area during roll compaction. PMID:20932904

Kuntz, Theresia; Schubert, Martin A; Kleinebudde, Peter

2011-01-01

191

Sintering titanium powders  

SciTech Connect

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.

Gerdemann, Stephen J.; Alman, David E.

2005-09-01

192

Review of stress-corrosion cracking in high-strength aluminum alloys. [Al alloys 7090, 7091, IN 9052 and Al-Li ingot metallurgy  

Microsoft Academic Search

Developments in understanding the mechanisms of stress-corrosion cracking (SCC) of high-strength aluminum alloys are highlighted from early dissolution models, to present hydrogen embrittlement dominated theories. Uncertainties in the present view of the SCC mechanism are identified. The means by which SCC susceptibility has been reduced in ingot metallurgy (I\\/M) alloys are described. The susceptibility of new powder metallurgy (P\\/M) alloys

J. R. Pickens; L. Christodoulou; T. J. Langan

2008-01-01

193

Influence of Powder Metallurgical Processing Routes on Phase Formations in a Multicomponent NbSi-Alloy  

NASA Astrophysics Data System (ADS)

Refractory metal silicide composites on the basis of Nbss-Nb5Si3 have been investigated as potential alternatives for nickel-base superalloys for years because of their low densities and good high-temperature strengths. NbSi-based composites are typically produced by arc-melting or casting. Samples in this study, however, were produced by powder metallurgy because of the potential for near net-shape component fabrication with very homogeneous microstructures. Either gas atomized powder or high-energy mechanically alloyed elemental powders were compacted by powder injection molding or hot isostatic pressing. Heat treatments were applied for phase stability evaluation. Slight compositional changes (oxygen, nitrogen, or iron) introduced by the processing route, i.e., powder production and consolidation, can affect phase formations and phase transitions during the process. Special focus is put on the distinction between different silicides (Nb5Si3 and Nb3Si) and silicide modifications (?-, ?-, and ?-Nb5Si3), respectively. These were evaluated by x-ray diffraction and energy-dispersive spectroscopy measurements with the additional inclusion of thermodynamic calculations using the calculated phase diagram method.

Seemüller, C.; Hartwig, T.; Mulser, M.; Adkins, N.; Wickins, M.; Heilmaier, M.

2014-09-01

194

Niobium-Alloyed high speed steel by powder metallurgy  

Microsoft Academic Search

A philosophy for the use of strong carbide formers like niobium in high speed steels is described. It follows the concept\\u000a of independently optimizing the compositions of the matrix (for maximum secondary hardening potential) and the volume fraction\\u000a of the blocky carbides (for protection against abrasive wear). Normally, the two are interdependent through the action of\\u000a the solidification equilibria, but

S. Karagöz; H. F. Fischmeister

1988-01-01

195

Micro-Metallurgy of Splats: Theory, Computer Simulation and Experiment  

NASA Astrophysics Data System (ADS)

Over the last one and half decades the constantly growing interest to a problem of rapid solidifying the melted micro-droplets of various materials at their impact with a surface has been marked. This phenomenon is at the basis of many technologies, such as plasma, detonation and flame spraying, arc-spray, spray-casting, micro-atomization of powders, solder-drop-printing in microelectronic, making the microcrystal and amorphous materials, and producing the high-temperature superconductors. The system micro-droplet - substrate is very suitable for a physical materials science in studies of the non-equilibrium phase diagrams of different alloys and composite materials under extreme conditions. Practically speaking we have dealings with independent scientific and technological line of investigation - micro-metallurgy of a small volume of melt at its collision with an obstacle surface or, in other words, splats’ micro-metallurgy. The paper presented is devoted to a brief review of theoretical, computational and experimental investigations carried out by composite authors during the last decade.

Solonenko, Oleg Pavlovich; Kudinov, Vladimir Vladimirovich; Smirnov, Andrey Vladimirovich; Cherepanov, Anatoly Nikolaevich; Popov, Vladimir Nikolaevich; Mikhalchenko, Alexander Anatol'Yevich; Kartaev, Evgeny Vladimirovich

196

Methods of manufacture of aluminum powders and their fields of application  

Microsoft Academic Search

Aluminum powders, flakes, pastes, and granules are being successfully used in various branches of the national economy, including powder metallurgy. The present-day scale of industrial manufacture of aluminum and aluminum alloy powder products can satisfy virtually all the known demands from industry. There is a need to increase industrial production of aluminum alloy granules by the method of centrifugal casting

V. G. Gopienko; V. P. Kiselev; N. S. Zobnina

1984-01-01

197

Electrostatic performance of various lubricant powders in P\\/M electrostatic die wall lubrication  

Microsoft Academic Search

Electrostatic die wall lubrication is an advanced lubrication technique in the production of machinery parts of powder metallurgy. Electrostatic performance of lubricants is one of key factors for successful operation. Among electrostatic parameters, the charge-to-mass ratio of dry lubricant powders has been considered to be the most critical factor to make good adhesion between the dry lubricant powders and the

X. Yang; S. J. Guo; B. F. Chen; F. Meng; Y. D. Lian

2006-01-01

198

Materials for Advanced Turbine Engines. Volume 1; Power Metallurgy Rene 95 Rotating Turbine Engine Parts  

NASA Technical Reports Server (NTRS)

An attempt was made to improve methods for producing powder metallurgy aircraft gas turbine engine parts from the nickel base superalloy known as Rene 95. The parts produced were the high pressure turbine aft shaft for the CF6-50 engine and the stages 5 through 9 compressor disk forgings for the CFM56/F101 engines. A 50% cost reduction was achieved as compared to conventional cast and wrought processing practices. An integrated effort involving several powder producers and a major forging source were included.

Pfouts, W. R.; Shamblen, C. E.; Mosier, J. S.; Peebles, R. E.; Gorsler, R. W.

1979-01-01

199

April 11, 2013 Powder Consolidation under Pressure  

E-print Network

April 11, 2013 Powder Consolidation under Pressure Wei-Jhe Sun Tablet, a consolidated powder structure, by considering the evolution of powder structure under compaction pressure.1 The mechanical, relative volume, and density to compaction pressure. A widely used equation is Heckel equation, which does

Thomas, David D.

200

Powder and particulate production of metallic alloys  

NASA Technical Reports Server (NTRS)

Developments of particulate metallurgy of alloyed materials where the final products is a fully dense body are discussed. Particulates are defined as powders, flakes, foils, silvers, ribbons and strip. Because rapid solidification is an important factor in particulate metallurgy, all of the particulates must have at least one dimension which is very fine, sometimes as fine as 10 to 50 microns, but move typically up to several hundred microns, provided that the dimension permits a minimum solidification rate of at least 100 K/s.

Grant, N. J.

1982-01-01

201

A Millennium of Metallurgy Recorded by Lake Sediments from  

E-print Network

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

Wolfe, Alexander P.

202

-OK 8>00jigLi Metallurgy Department  

E-print Network

-OK 8°>00jigLi 00 tf) Risø-M-28B Metallurgy Department Publications 1988 Risø National Laboratory, DK-4000 Roskilde, Denmark August 1989 #12;Metallurgy Department Publications 1988 Edited by A by the staffof the Metallurgy Department during 1988 is given. The list comprises journal papers, conference

203

62j opo2>(o Metallurgy Department December 197 3  

E-print Network

wm v b e c 62j opo2>(o Metallurgy Department December 197 3 S-7913 Risø-I-63 CQBRQS1QN ASPECTS QP H/ELKRAFT's waste management preset, phase 2. #12;Metallurgy Department S-7913 Risø-I-63 December 1979 CORROSION figurer Dato December 1979 Afdeling eller gruppe Metallurgi Gruppens eget registreringsnummer S-7913

204

* TOTT(^/Oi\\ Riso-R-402 Metallurgy Department  

E-print Network

o o o o 00 U *· TOTT(^/Oi\\ Riso-R-402 ^ Metallurgy Department Progress Report for the period l METALLURGY DEPARTMENT PROGRESS REPORT FOR THE PERIOD 1 JANUARY TO 31 DECEMBER 1978 Abstract. The activities of the Metallurgy Department at Risø during 1978 are described. The work is presented in four chap- ters: General

205

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)

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.

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

2011-10-01

206

Future Developments in NonFerrous Metallurgy  

Microsoft Academic Search

A major advance in the physical metallurgy of non-ferrous metals in recent years has been the use of knowledge, built on the foundation laid by Rosenhain, to predict unusual properties which can have considerable value in engineering applications. Much of the paper is therefore concerned with discussing these new discoveries and showing how they provide a possible escape from the

G. B. Brook; W. E. Duckworth

1976-01-01

207

X-ray photoelectron spectroscopy (XPS) investigation of the surface film on magnesium powders.  

PubMed

Magnesium (Mg) and its alloys are attractive for use in automotive and aerospace applications because of their low density and good mechanical properties. However, difficulty in forming magnesium and the limited number of available commercial alloys limit their use. Powder metallurgy may be a suitable solution for forming near-net-shape parts. However, sintering pure magnesium presents difficulties due to surface film that forms on the magnesium powder particles. The present work investigates the composition of the surface film that forms on the surface of pure magnesium powders exposed to atmospheric conditions and on pure magnesium powders after compaction under uniaxial pressing at a pressure of 500 MPa and sintering under argon at 600 °C for 40 minutes. Initially, focused ion beam microscopy was utilized to determine the thickness of the surface layer of the magnesium powder and found it to be ~10 nm. The X-ray photoelectron analysis of the green magnesium sample prior to sintering confirmed the presence of MgO, MgCO(3)·3H(2)O, and Mg(OH)(2) in the surface layer of the powder with a core of pure magnesium. The outer portion of the surface layer was found to contain MgCO(3)·3H(2)O and Mg(OH)(2), while the inner portion of the layer is primarily MgO. After sintering, the MgCO(3)·3H(2)O was found to be almost completely absent, and the amount of Mg(OH)(2) was also decreased significantly. This is postulated to occur by decomposition of the compounds to MgO and gases during the high temperature of sintering. An increase in the MgO content after sintering supports this theory. PMID:22524956

Burke, Paul J; Bayindir, Zeynel; Kipouros, Georges J

2012-05-01

208

Mound powder loader, Mod 1  

SciTech Connect

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.

Gress, A.V. Jr.

1985-08-21

209

Phosphorus as sintering activator in powder metallurgical steels: characterization of the distribution and its technological impact  

Microsoft Academic Search

Powder metallurgy is a highly developed method of manufacturing reliable ferrous parts. The main processing steps in a powder metallurgical line are pressing and sintering. Sintering can be strongly enhanced by the formation of a liquid phase during the sintering process when using phosphorus as sintering activator. In this work the distribution (effect) of phosphorus was investigated by means of

Dragan Krecar; Vassilka Vassileva; Herbert Danninger; Herbert Hutter

2004-01-01

210

The EDM surface: Topography, chemistry, and metallurgy  

SciTech Connect

The surface created by the electric discharge machining (EDM) process is of special interest because it has been shown to have a negative effect on the fatigue properties of many alloys. An understanding of the surface metallurgy and chemistry is important in predicting those alloys which are most susceptible to failure. Remedial actions, including thickness minimization, alteration, or removal of the surface layer are addressed.

Fuller, J.E.

1991-01-01

211

Advanced NDE Technologies for Powder Metal Components  

SciTech Connect

Nondestructive evaluation encompasses numerous technologies that assess materials and determine important properties. This paper demonstrates the applicability of several of these technologies to the field of powder metallurgy. The usual application of nondestructive evaluation is to detect and quantify defects in fully sintered product. But probably its most appealing role is to sense problems earlier in the manufacturing process to avoid making defects at all. Also nondestructive evaluation can be incorporated into the manufacturing processes to monitor important parameters and control the processes to produce defect free product. Nondestructive evaluation can characterize powders, evaluate components in the green state, monitor the sintering process, and inspect the final component.

Martin, P; Haskins, J; Thomas, G; Dolan, K

2003-05-01

212

Shear consolidation of powders  

NASA Astrophysics Data System (ADS)

The manufacture of bulk parts from metastable powder materials requires new approaches to cold consolidation. One potential technique is equal-channel angular extrusion (ECAE), a simple shear process. This thesis describes an investigation into the effects of confining pressure (back-pressure) on single-pass, right-angled ECAE consolidation of copper and aluminum 6061 powders below 250°C, using an extrusion machine designed and constructed for this purpose. Empirical relationships for punch pressure requirements as a function of back-pressure and billet length are determined experimentally and compared with published theory. Powder particle boundaries are examined in extruded billets, revealing pores and regions of localized shear formed under low back-pressure conditions. This shear localization is considered with a visualization experiment involving wax spheres in a transparent die, and a linear stability analysis of simple shear of a thin strip of material described by a generalized powder yield function and flow rule. The back-pressures required to obtain homogeneous, pore-free microstructures are determined, and related to the response of the powders during the initial compaction stage of ECAE. Interparticle bond formation in cold powder processing is briefly discussed in the context of multi-pass extrusions.

Hanna, James A.

213

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

214

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

215

Fatigue-crack propagation in aluminum-lithium alloys processed by power and ingot metallurgy  

SciTech Connect

Fatigue-crack propagation behavior in powder-metallurgy (P/M) aluminum-lithium alloys, namely, mechanically-alloyed (MA) Al-4.0Mg-1.5Li-1.1C-0.80{sub 2} (Inco 905-XL) and rapid-solidification-processed (RSP) Al-2.6Li-1.0Cu-0.5Mg-0.5Zr (Allied 644-B) extrusions, has been studied, and results compared with data on an equivalent ingot-metallurgy (I/M) Al-Li alloy, 2090-T81 plate. Fatigue-crack growth resistance of the RSP Al-Li alloy is found to be comparable to the I/M Al-Li alloy; in contrast, crack velocities in MA 905-XL extrusions are nearly three orders of magnitude faster. Growth-rate response in both P/M Al-Li alloys, however, is high anisotropic. Results are interpreted in terms of the microstructural influence of strengthening mechanism, slip mode, grain morphology and texture on the development of crack-tip shielding from crack-path deflection and crack closure. 14 refs., 7 figs., 2 tabs.

Venkateswara Rao, K.T.; Ritchie, R.O. (Lawrence Berkeley Lab., CA (United States)); Kim, N.J. (Pohang Inst. of Science and Technology (Korea, Republic of)); Pizzo, P.P. (San Jose State Univ., CA (United States))

1990-04-01

216

Mystery Powders  

NSDL National Science Digital Library

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.

American Chemical Society

2000-01-01

217

Features of the effect of nanodispersed additives on the sintering process and properties of powdered cobalt alloys  

Microsoft Academic Search

Some questions on the development of the cobalt-based composite material dispersion-hardened by nanoparticles using powder\\u000a metallurgy are considered. The powders of WC, ZrO2, and Al2O3 are used as nanoparticles that harden the Co matrix. The nanoparticles are mixed with cobalt powder of extra fine grade Co\\u000a in a centrifugal planetary mill. It is shown that the treatment according to the

A. A. Zaitsev; V. V. Kurbatkina; E. A. Levashov

2008-01-01

218

Fluidized reduction of oxides on fine metal powders without sintering  

NASA Technical Reports Server (NTRS)

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.

Hayashi, T.

1985-01-01

219

Cold forging of sintered iron-powder preforms  

Microsoft Academic Search

The paper reports on an investigation into various aspects of cold forging of iron-powder preforms which have been compacted and sintered from atomised iron powder. An upperbound solution is constructed for determining the die pressures developed during the cold forging of iron powder under axisymmetric and plane-strain condition. The results so obtained are discussed critically to illustrate the interaction of

G. Sutradhar; A. K. Jha; S. Kumar

1995-01-01

220

Charpy Impact Testing University of Saskatchewan -Mechanical Engineering -Materials Science and Metallurgy  

E-print Network

and Metallurgy ID: Mat0020 Rev: 002 Date: Nov. 8, 2011 Page: 1 of 6 Impact Testing with the Charpy Impact Tester - Materials Science and Metallurgy ID: Mat0020 Rev: 002 Date: Nov. 8, 2011 Page: 2 of 6 1. SIGNATURES Science and Metallurgy ID: Mat0020 Rev: 002 Date: Nov. 8, 2011 Page: 3 of 6 2. VERSION HISTORY Handwritten

Saskatchewan, University of

221

Chemistry and Metallurgy Research Facility The Los Alamos National Laboratory (LANL) Chemistry and  

E-print Network

CMR Chemistry and Metallurgy Research Facility The Los Alamos National Laboratory (LANL) Chemistry and Metallurgy Research (CMR) building supports research and experimental activities for plutonium and uranium analytical chemistry and metallurgy. In 1952, the first LANL CMR facility was completed. At that time

222

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

E-print Network

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

Cambridge, University of

223

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

224

Microhardness Testing -Mitutoyo University of Saskatchewan -Mechanical Engineering -Materials Science and Metallurgy  

E-print Network

Science and Metallurgy ID: Mat0017 Rev: 002 Date: Nov. 8, 2011 Page: 1 of 5 Vickers Hardness Testing Engineering - Materials Science and Metallurgy ID: Mat0017 Rev: 002 Date: Nov. 8, 2011 Page: 2 of 5 1 of Saskatchewan - Mechanical Engineering - Materials Science and Metallurgy ID: Mat0017 Rev: 002 Date: Nov. 8

Saskatchewan, University of

225

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

226

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

SciTech Connect

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.

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

1998-09-01

227

PETROLEUM SOCIETY CANADIAN INSTITUTE OF MINING, METALLURGY & PETROLEUM  

E-print Network

1 PETROLEUM SOCIETY CANADIAN INSTITUTE OF MINING, METALLURGY & PETROLEUM PAPER 2002-092 Effects of Alberta This paper is to be presented at the Petroleum Society's Canadian International Petroleum of the meeting. This paper and any discussion filed will be considered for publication in Petroleum Society

Hossain, M. Enamul

228

Materials and Metallurgy Materials Science and Metallurgical Engineering  

E-print Network

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

Provancher, William

229

A New Approach on Diffusion Welding of Fe–Cu–C and Fe–Zn–C Powder Metal Parts  

Microsoft Academic Search

Cylindrical parts made from pre-strengthened Fe–Cu–C and Fe–Zn–C powders, fabricated under 1000 MPa-cold press, were welded in a vacuum furnace at different temperatures by diffusion welding. A novel approach was used where powder metallurgy parts were sintered together with diffusion welding with no extra pressure applied during the welding process. Chemical composition, cold press pressure, and sintering time (consequently welding time)

Y. Babayev; F. Kahraman; S. Karadeniz

2010-01-01

230

Synthesis and processing of monosized oxide powders  

DOEpatents

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.

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

1985-09-24

231

Synthesis and processing of monosized oxide powders  

DOEpatents

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.

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

1985-01-01

232

Energetic powder  

DOEpatents

Fluoroalkylsilane-coated metal particles. The particles have a central metal core, a buffer layer surrounding the core, and a fluoroalkylsilane layer attached to the buffer layer. The particles may be prepared by combining a chemically reactive fluoroalkylsilane compound with an oxide coated metal particle having a hydroxylated surface. The resulting fluoroalkylsilane layer that coats the particles provides them with excellent resistance to aging. The particles can be blended with oxidant particles to form energetic powder that releases chemical energy when the buffer layer is physically disrupted so that the reductant metal core can react with the oxidant.

Jorgensen, Betty S. (Jemez Springs, NM); Danen, Wayne C. (Los Alamos, NM)

2003-12-23

233

Flow sheet, fabrication, and properties comparison of nitride fuel obtained by powder metallurgy and gelation processes  

Microsoft Academic Search

The Paul Scherrer Institute (PSI) in Switzerland, and the Commissariat a l'Energie Atomique (CEA) in France, collaboration on advanced nitride fuel has concentrated on a program of comparative experimental irradiation of (U,Pu)N fuel in the PHENIX Fast Reactor. The two parties have undertaken studies to ensure the success of the experiment. The PSI work has been mainly carried out for

C. Prunier; D. Warin; R. Stratton; G. Ledergerber

1992-01-01

234

Application of powder metallurgy techniques for the development of non-toxic ammunition. Final CRADA report  

SciTech Connect

The purpose of the Cooperative Research and Development Agreement (CRADA) between Martin Marietta Energy Systems, Inc., and Delta Frangible Ammunition (DFA), was to identify and evaluate composite materials for the development of small arms ammunition. Currently available small arms ammunition utilizes lead as the major component of the projectile. The introduction of lead into the environment by these projectiles when they are expended is a rapidly increasing environmental problem. At certain levels, lead is a toxic metal to the environment and a continual health and safety concern for firearm users as well as those who must conduct lead recovery operations from the environment. DFA is a leading supplier of high-density mixtures, which will be used to replace lead-based ammunition in specific applications. Current non-lead ammunition has several limitations that prevent it from replacing lead-based ammunition in many applications (such as applications that require ballistics, weapon recoil, and weapon function identical to that of lead-based ammunition). The purpose of the CRADA was to perform the research and development to identify cost-effective materials to be used in small arms ammunition that eventually will be used in commercially viable, environmentally conscious, non-lead, frangible and/or non-frangible, ammunition.

Lowden, R. [Lockheed Martin Energy Systems, Inc., Oak Ridge, TN (United States); Kelly, R. [Delta Defense, Inc., Arlington, VA (United States)

1997-05-30

235

Wear resistant tools for reproduction technologies produced by micro powder metallurgy  

Microsoft Academic Search

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

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

2002-01-01

236

Claw pole armature permanent magnet machines exploiting soft iron powder metallurgy  

Microsoft Academic Search

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

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

1997-01-01

237

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

Microsoft Academic Search

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

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

2008-01-01

238

Ductilization of Mo-Si solid solutions manufactured by powder metallurgy  

SciTech Connect

Mo-1.5 at.% Si alloys with additions of either Y{sub 2}O{sub 3} or Zr were manufactured by mechanical alloying. The Y{sub 2}O{sub 3} particles reduced the grain size and increased the room temperature strength, but did not alleviate the brittleness of previously investigated Mo-1.5 at.% Si without Y{sub 2}O{sub 3}. Additions of Zr, on the other hand, resulted not only in a fine grain size and an extremely high bend strength ({approx}2 GPa), but also in limited bend ductility at room temperature. Zr additions are seen to be beneficial for three reasons. First, Zr reduces the grain size. Second, Zr getters detrimental oxygen by forming ZrO{sub 2} particles (which in turn help to pin the grain boundaries). Third, in situ Auger analysis shows that Zr reduces the concentration of Si segregated at the grain boundaries. This is thought to enhance the grain boundary cohesive strength and thus leads to the observed ductility.

Saage, H. [University of Magdeburg, Germany; Krueger, M. [Otto-von-Guericke Universitat, Magdeburg, Germany; Sturm, D. [University of Magdeburg, Germany; Heilmaier, M. [University of Magdeburg, Germany; Schneibel, J H [University of Magdeburg, Germany; George, Easo P [ORNL; Heatherly Jr, Lee [ORNL; Somsen, Ch. [Ruhr University, Bochum, Germany; Eggeler, G. [Ruhr University, Bochum, Germany; Yang, Ying [CompuTherm LLC, Madison, WI

2009-01-01

239

Superplastic behavior at high strain rate of rapidly solidified powder metallurgy Al-Li alloy  

Microsoft Academic Search

A number of studies which reveal that superplasticity can sometimes occur at an extremely high strain rate (> 10[sup [minus]1]s[sup [minus]1]) have been reported in several classes of materials, including metal-matrix composites and mechanically-alloyed (MA) materials. Since multiphase aluminum alloys processed by rapid solidification techniques can have fine stable grains, the interest in the superplastic behavior of these alloys increased

Zhongqi Cui; Wang Zhong; Qingbin Wei

1994-01-01

240

Reliability comparison of two metallurgies for ceramic ball grid array  

Microsoft Academic Search

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

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

1995-01-01

241

The Monitoring System of Zinc Metallurgy Leaching Process  

Microsoft Academic Search

The paper introduces the characteristics and functions of fieldbus technology through control of pH value in wet zinc metallurgy process. S7-300 PLC is master station, S7-200 PLC with communication module are secondary stations, and hardware configuration or software designing on profibus-DP are use of SETP7, monitoring software WinCC of master station monitor the system state and process data. So realize

Xianzhong He; Yanjie Guo

2009-01-01

242

The welding metallurgy of Custom Age 625 PLUS alloy  

Microsoft Academic Search

The authors discuss the welding metallurgy (solidification behavior, mechanical properties of weld metal, and susceptibility to fusion zone hot cracking) of Carpenter Custom Age 625 PLUS alloy. This alloy solidifies to a nickel austenitic matrix with the formation of a Nb-rich γ\\/Laves terminal solidification constituent. The low Si and C concentrations in combination with a lower Nb content (3.4wt-%) in

M. J. Cieslak; T. J. Headley; R. B. Frank

1989-01-01

243

Metallurgy, environmental pollution and the decline of Etruscan civilisation  

Microsoft Academic Search

Background, aim and scope  The Etruscans were justifiably famous in antiquity for their advanced metallurgy and for the rich mineral resources of their\\u000a region (including La Tolfa, the Colline Metallifere, Mont’Amiata and Elba). We offer a new perspective on certain Iron Age\\u000a and Archaic (ca. 1,000–480 bc) Etruscan industrial and habitation sites, and on the problem of heavy metal poisoning, still being

Adrian P. Harrison; Ilenia Cattani; Jean M. Turfa

2010-01-01

244

A comparison of the sintering of various titanium powders  

SciTech Connect

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.

Gerdemann, Stephen J.; Alman, David E.

2005-02-01

245

Wet powder seal for gas containment  

DOEpatents

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.

Stang, Louis G. (Sayville, NY)

1982-01-01

246

Wet powder seal for gas containment  

SciTech Connect

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.

Stang, L.G.

1982-01-19

247

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

248

ilvVJl!U)jXy Ris-R-503 Metallurgy Department  

E-print Network

CO GO ilvVJl!U)jXy Risø-R-503 Metallurgy Department Progress Report for the Period 1 January - 31 December 1983 Risø National Laboratory, DK-4000 Roskilde, Denmark June 1984 #12;1 Risø-R-503 METALLURGY of the Metallurgy Department at Risø during 1983 are described. The work is presented in three chap- ters: General

249

Exploring Baking Powder  

NSDL National Science Digital Library

In this activity, learners examine baking powder, a combination of three powders: baking soda, cream of tartar, and cornstarch. Learners use their data from the previous activity (see related resource) to identify these three powders as possible ingredients. Then, they test combinations of these powders to determine the active ingredients in baking powder.

Kessler, James H.; Galvan, Patricia M.

2007-01-01

250

Materials Science & Metallurgy Part II Metallography, H. K. D. H. Bhadeshia  

E-print Network

Materials Science & Metallurgy Part II Metallography, H. K. D. H. Bhadeshia Introduction to Quantitative Metallography Standard Stereological Terms The following terminology is established in stereology

Cambridge, University of

251

C-Fe Hardmetals with High Hardness Fabricated by Direct Current Arc In Situ Metallurgy  

NASA Astrophysics Data System (ADS)

Coarse-grained W p C-Fe ( P = 1,2) hardmetals were fabricated with tungsten and graphite powders by the direct current arc in situ metallurgy technique. Investigations on the microstructures, morphology evolution, and performance for the resultant materials were also carried out. It is found that with decreasing the applied current, the content of W2C decreases, but the content and grain size of WC increase. The largest WC grain can reach around 150 ?m. The shape of WC changes from hexangular prism to truncated triangle prism, and ultimately transforms into triangular prism due to the different growth rates of the prismatic planes. Furthermore, a layer by layer growth mode of the WC was observed. The performance tests indicate that the average microhardnesses of the WC and W2C are 2559 and 1916 HV0.2, respectively. For the WC grain, the microhardness of 2761 HV0.2 of the triangular basal plane is much higher than the 2357 HV0.2 of the prismatic plane.

Chi, Jing; Li, Huiqi; Zhao, Jian; Wang, Shufeng; Li, Min; Ji, Qiang; Li, Jiannan

2014-11-01

252

Powder treatment process  

DOEpatents

(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.

Weyand, John D. (Greensburg, PA)

1988-01-01

253

Powder treatment process  

DOEpatents

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.

Weyand, J.D.

1988-02-09

254

Powder lubrication of faults by powder rolls in gouge zones  

NASA Astrophysics Data System (ADS)

Powder-lubrication by fault gouge can be an effective mechanism of dynamic weakening of faults (Reches & Lockner, 2010); however, the physical mechanisms of this lubrication are poorly understood. While the flow of coarse-grained (> 100 ?m) materials, e.g. glass beads or quartz sand, was extensively studied, the flow of fine-grained (< 1 ?m) powders, e.g., fault-gouge and nano-powders, have remained enigmatic. We report here experimental results of a new efficient mechanism for powder lubrication. We conducted friction tests on high-velocity rotary shear apparatus (Reches & Lockner, 2010). Two types of experimental faults were tested: (1) faults made of solid, igneous rocks (granite, tonalite and diorite); and (2) fault-zones made of 2-3 mm thick layer of granular materials (oolites, calcite or gypsum) sheared in a confined cell. We performed 21 runs with total slip of 0.14-13 m, normal stress of 1.2-14.5 MPa, slip velocity of 0.012-0.97 m/s. The ultra-microscopic (SEM and AFM) analysis of the experimental slip surfaces revealed two outstanding features in 17 out of the 21 experiments: (1) localized fault-slip along Principal Slip Zones (PSZs) that are composed of a dense, shiny, cohesive crust, 0.5-1 micron thick, that overlaid a porous substrate, and (2) elongated rolls composed of gouge-powder into three-dimensional structures of closely-packed powder grains, (20-50 nm in size). The rolls are cylindrical, 0.75-1.4 micron wide, and 1.7-30 micron long, with smooth outer surface, and laminated, concentric layers of compacted grains. The rolls were exclusively found on the PSZs. Many rolls were destroyed fracturing and smearing on the PSZ, suggesting that the rolls underwent a life cycle of formation and destruction. Significant macroscopic friction reduction was measured in experiments with observed rolls, and no (or minor) friction reduction in the four experiments without rolls. The final, reduced friction coefficients have a general reciprocal relation to the rolls surface coverage, suggesting that increased development of rolls (= increasing surface coverage) enhanced fault weakening. We applied the Eldredge and Tabor (1955) model for rolling friction to the AFM observed morphology of the rolls and PSZs, and found good agreement between measured and modeled friction coefficients. We conclude that the measured friction reduction reflects a transition from sliding-dominated slip to rolling-dominated slip due to the presence and density of powder rolls. We further argue that powder rolling is an effective mechanism of powder lubrication, and that spontaneous growth of such rolls along crustal faults is likely to control earthquake weakening.

Chen, X.; Madden, A. S.; Reches, Z.

2013-12-01

255

Pressing behavior of atomized iron powders  

Microsoft Academic Search

The optimum zinc stearate content, ensuring the greatest compressibility of a powder at a given pressing pressure, is determined mainly by the volume of interparticle pores. The higher the density of a compact and the smaller the size of its pores, the smaller is the amount of zinc stearate it can hold. The weakening action of zinc stearate, which manifests

A. F. Zhornyak; V. E. Oliker

1981-01-01

256

Mach stem characterization in Mbar designs using RSR powder  

SciTech Connect

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).

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

1985-01-01

257

Materials Science & Metallurgy Master of Philosophy, Materials Modelling, Course MP10, Process Modelling, H. K. D. H. Bhadeshia  

E-print Network

Materials Science & Metallurgy Master of Philosophy, Materials Modelling, Course MP10, Process.­E. Svensson. The metallurgy of the welded joint can be categorised into two major regions, the fusion zone

Cambridge, University of

258

Materials Science & Metallurgy Master of Philosophy, Materials Modelling, Course MP6, Kinetics and Microstructure Modelling, H. K. D. H. Bhadeshia  

E-print Network

Materials Science & Metallurgy Master of Philosophy, Materials Modelling, Course MP6, Kinetics in metallurgy. To form a complete design­technology, it is consequently necessary to re- sort to careful

Cambridge, University of

259

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

E-print Network

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

Huang, Haimei

260

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

E-print Network

, 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

Galias, Zbigniew

261

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

E-print Network

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

Galias, Zbigniew

262

SUMMARIES ON PHYSICAL RESEARCH IN METALLURGY, SOLID STATE PHYSICS, AND CERAMICS  

Microsoft Academic Search

The objectives and current status of the individual research projects ; supported by the Metallurgy and Materials Branch, Division of Research, in the ; fields of physical metallurgy, solid state physics, and physical ceramics are ; summarized. Included is the research conducted at the Commission's laboratories ; as well as that performed at university and other laboratories. The information ;

R. R. ed

1959-01-01

263

Simulation Study for Complex Shaped Pressing of Ceramic Powder  

NASA Astrophysics Data System (ADS)

The modified Drucker-Prager Cap elasto-plastic constitutive model is used for the calculation that performed using the finite element code ABAQUS 6.4 to simulate densification of alumina powder of complex shaped sample. Four-node axisymmetric elements were used for the powder compact and two-node axisymmetric rigid surface elements were used for the interfaces between powder and die and punches. Finite element result predicts very high density in the inner top region and relatively uniform density distribution is observed in the region far from the axisymmetric axis. The model developed can describe not only the compaction and decompression phases, but also the ejection phase.

Abdullah, Omed Gh.; Rasin, Fadhil Abd; Al-Dhahir, Tariq A.

2010-07-01

264

1863 Thomas Egleston Jr., a graduate of Yale and the Ecole des Mines in Paris, proposes a school of metallurgy  

E-print Network

of metallurgy and mining in New York City, and Columbia College Trustee George Templeton Strong champions his. 1903 Irving H. Langmuir graduates with a degree in metallurgy and goes on to make important advances of Earth and Environmental Engineering (EEE). Originally focused on metallurgy and resource extraction

Yang, Junfeng

265

Advances in Physical Metallurgy, edited by S. Banerjee and R. V. Ramanujan, Gordon and Breach Publishers, 1996  

E-print Network

Advances in Physical Metallurgy, edited by S. Banerjee and R. V. Ramanujan, Gordon and Breach into metallurgy. But this is where cre- ativity comes in. I recall someone saying that high TC superconductors are metallic. But how does "Metallurgy of ceramic cutting tools" qualify? I guess that even the ceramics

Cambridge, University of

266

Production of ultra clean gas-atomized powder by the plasma heated tundish technique  

SciTech Connect

The paper describes the improvements in cleanliness for different types of gas atomized powders produced by holding the melt in a Plasma Heated Tundish (PHT) before atomization. The cleanliness is measured on Hot Isostatically Pressed (HIP) or extruded samples. Significant improvements in slag levels and material properties have been achieved. On extruded powder metallurgy stainless steel and nickel alloy tubes, the rejection rate in ultra-sonic testing was reduced drastically. Tool steels and high speed steels have greatly improved ductility and bend strength.

Tingskog, T.A. [Anval Inc., Rutherford, NJ (United States); Andersson, V. [Anval Nyby Powder A.B., Torshalla (Sweden)

1996-12-31

267

Resin-Powder Dispenser  

NASA Technical Reports Server (NTRS)

Resin-powder dispenser used at NASA's Langley Research Center for processing of composite-material prepregs. Dispenser evenly distributes powder (resin polymer and other matrix materials in powder form) onto wet uncured prepregs. Provides versatility in distribution of solid resin in prepreg operation. Used wherever there is requirement for even, continuous distribution of small amount of powder.

Standfield, Clarence E.

1994-01-01

268

Preparation of titanium diboride powder  

DOEpatents

Finely-divided titanium diboride or zirconium diboride powders are formed by reacting gaseous boron trichloride with a material selected from the group consisting of titanium powder, zirconium powder, titanium dichloride powder, titanium trichloride powder, and gaseous titanium trichloride.

Brynestad, Jorulf (Oak Ridge, TN); Bamberger, Carlos E. (Oak Ridge, TN)

1985-01-01

269

The mysterious world of plutonium metallurgy: Past and future  

SciTech Connect

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.

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

1998-12-31

270

Polymer quenched prealloyed metal powder  

DOEpatents

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.

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

2001-01-01

271

Process for synthesizing compounds from elemental powders and product  

DOEpatents

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.

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

1993-01-01

272

NanoComposite Stainless Steel Powder Technologies  

SciTech Connect

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.

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

2012-07-25

273

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....

274

Mesoscale Simulations of Power Compaction  

SciTech Connect

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.

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

2009-08-06

275

Composite powder particles  

NASA Technical Reports Server (NTRS)

A liquid coating composition including a coating vehicle and composite powder particles disposed within the coating vehicle. Each composite powder particle may include a magnesium component, a zinc component, and an indium component.

Parker, Donald S. (Inventor); MacDowell, Louis G. (Inventor)

2009-01-01

276

Precision powder feeder  

DOEpatents

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.

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

2001-07-10

277

The influence of microstructure on the sintering process in crystalline metal powders investigated by positron lifetime spectroscopy: II. Tungsten powders with different powder-particle sizes  

Microsoft Academic Search

Compacts of tungsten powder with five different powder-particle sizes (from 0953-8984\\/11\\/7\\/010\\/img7 to 0953-8984\\/11\\/7\\/010\\/img8) are subjected to pressureless sintering. We investigate the change in microstructure during the sintering process by positron lifetime spectroscopy. So as to be able to distinguish between defects having the same positron lifetime, we investigate their kinetics when the sample is annealed. In particular, we consider the

T. E. M. Staab; R. Krause-Rehberg; B. Vetter; B. Kieback; G. Lange; P. Klimanek

1999-01-01

278

Global Compact  

NSDL National Science Digital Library

The Global Compact is a joint project of the International Labor Organization (ILO), the United Nations Environmental Programme (UNEP), and the Office of the High Commissioner for Human Rights. The site outlines the nine principles drafted at the World Economic Forum on January 31, 1999 to serve as guidelines for world businesses. The principles address three basic areas of concern: human rights, labor standards, and environment. The Global Compact also provides means and methods for enacting these principles, including case studies and research from the ILO and the UNEP. The site's Country Information section is a searchable database of labor, human rights, and environmental information from Abkhyazia to Zimbabwe. The News and Reviews section contains current and archived news, as well as statements about the Global Compact from UN Secretary General Kofi Annan and Secretary General Amnesty International Pierre Sane among others. Here, users will also find an analytical overview of the research and debates over these topics.

279

Gelcasting superalloy powders  

Microsoft Academic Search

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

Janney

1995-01-01

280

The powder sintering and isothermal forging of Ti-10V-2Fe-3Al  

NASA Astrophysics Data System (ADS)

The synthetic technology of powder sintering and isothermal forging was explored to prepare a powder Ti-10V-2Fe-3Al (Ti-1023) alloy. Hydride-dehydride powder was provided from unqualified Ti-1023 ingot alloy because of “beta fleck” defect. After cold isostatic pressing and sintering, the compact presented uniform chemical composition, but lamella alpha microstructure. Isothermal forging technology was used to further densify the sintered compact and improve the microstructure and properties. The final forged compact exhibited equiaxed, recrystallized, and fined alpha phase microstructure, and excellent tensile properties at room temperature.

Guo, Hongzhen; Zhao, Zhanglong; Duan, Chunyan; Yao, Zekun

2008-11-01

281

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

NASA Astrophysics Data System (ADS)

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.

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

2013-12-01

282

STEEL AND GRAY IRON FOAM BY POWDER METALLURGICAL SYNTHESIS  

Microsoft Academic Search

Foam synthesis, from several blends of pure iron, commercial graphite and gray iron powders plus the foaming agent (MgCO3), were carried out. These powders, in determined proportions and commercial graphite with up to 2,5Wt%, were blended in a small tumbler-type ball mill for 1½ hours. Then, they were compacted by means of a 20 mm diameter die, to obtain 30

J. Muriel; A. Sánchez Roa; W. Barona Mercado; H. Sánchez Sthepa

2009-01-01

283

Hot-press sintering studies of amorphous silicon nitride powders  

Microsoft Academic Search

The hot-press sintering behaviour of amorphous Si3N4 powders prepared from the ammonia pyrolysis of polycarbosilane or hydridopolysilazane polymers was studied. In the presence of yttria and alumina, the amorphous powders sintered to > 98% of theoretical density at 2023 K. Both the microstructure and average four-point MOR bend strengths, of test bars machined from the sintered compacts were comparable to

G. T. Burns; J. A. Ewald; K. Mukherjee

1992-01-01

284

An investigation of the influence of powder particle size on microstructure and hardness of bulk samples of tungsten carbide  

Microsoft Academic Search

Bulk tungsten carbide samples were prepared by consolidating tungsten carbide powders using plasma pressure compaction. Three different powder particle sizes were chosen and the samples were obtained by consolidating the particles under conditions of pulse and no-pulse. Microstructural observations and density measurements provide sufficient evidence for the presence of porosity even after consolidation at 1500 °C. Regardless of initial powder

T. S. Srivatsan; R. Woods; M. Petraroli; T. S. Sudarshan

2002-01-01

285

Compact accelerator  

DOEpatents

A compact linear accelerator having at least one strip-shaped Blumlein module which guides a propagating wavefront between first and second ends and controls the output pulse at the second end. Each Blumlein module has first, second, and third planar conductor strips, with a first dielectric strip between the first and second conductor strips, and a second dielectric strip between the second and third conductor strips. Additionally, the compact linear accelerator includes a high voltage power supply connected to charge the second conductor strip to a high potential, and a switch for switching the high potential in the second conductor strip to at least one of the first and third conductor strips so as to initiate a propagating reverse polarity wavefront(s) in the corresponding dielectric strip(s).

Caporaso, George J. (Livermore, CA); Sampayan, Stephen E. (Manteca, CA); Kirbie, Hugh C. (Los Alamos, NM)

2007-02-06

286

TRADITIONAL METALLURGY, NANOTECHNOLOGIES AND STRUCTURAL MATERIALS: A SORBY AWARD LECTURE  

SciTech Connect

Traditional metallurgical processes are among the many ''old fashion'' practices that use nanoparticles to control the behavior of materials. Many of these practices were developed long before microscopy could resolve nanoscale features, yet the practitioners learned to manipulate and control microstructural elements that they could neither see nor identify. Furthermore, these early practitioners used that control to modify microstructures and develop desired material properties. Centuries old colored glass, ancient high strength steels and medieval organ pipes derived many of their desirable features through control of nanoparticles in their microstructures. Henry Sorby was among the first to recognize that the properties of rocks, minerals, metals and organic materials were controlled by microstructure. However, Mr. Sorby was accused of the folly of trying to study mountains with a microscope. Although he could not resolve nanoscale microstructural features, Mr. Sorby's observations revolutionized the study of materials. The importance of nanoscale microstructural elements should be emphasized, however, because the present foundation for structural materials was built by manipulating those features. That foundation currently supports several multibillion dollar industries but is not generally considered when the nanomaterials revolution is discussed. This lecture demonstrates that using nanotechnologies to control the behavior of metallic materials is almost as old as the practice of metallurgy and that many of the emergent nanomaterials technologists are walking along pathways previously paved by traditional metallurgists.

Louthan, M

2007-07-17

287

Determination of cerium in materials of ferrous metallurgy  

SciTech Connect

The determination of low contents of cerium in highly alloyed steels and alloys involves a long and laborious separation from accompanying components. A method of separation by adsorption of cerium fluoride in silicon dioxide, previously used in analytical laboratories of the rare-metal industry in the analysis of mineral raw materials and technological solution, has been used to increase the selectivity and rapidity of the separation of cerium. The purpose of this work was to study the possibility of using this method of separation of cerium in the analysis of highly alloyed steels and alloys. The degree of precipitation of cerium fluoride in the presence of iron (the basis of materials of ferrous metallurgy), which has virtually no effect on the adsorption process, was studied. The degree of adsorption is also 95-100% in the presence of 1 g of iron. After cerium was separated from accompanying components, it was determined by amperometric and photometric methods (the latter with arsenazo III) and by inversion voltammetry. Thus, the proposed method of separation from accompanying elements in alloyed steels is selective and rapid and permits the determination of microgram quantities of cerium with the requisite accuracy.

Popkova, G.N.; Fedorova, N.D.; Zubritskaya, L.D. [I.P. Bardin Central Scientific Research Inst. of Ferrous Metallurgy, Ekaterinburg (Russian Federation)

1994-06-01

288

Macromolecular metallurgy of binary mesocrystals via designed multiblock terpolymers.  

PubMed

Self-assembling block copolymers provide access to the fabrication of various ordered phases. In particular, the ordered spherical phases can be used to engineer soft mesocrystals with domain size at the 5-100 nm scales. Simple block copolymers, such as diblock copolymers, form a limited number of mesocrystals. However multiblock copolymers are capable to form more complex mesocrystals. We demonstrate that designed B1AB2CB3 multiblock terpolymers, in which the A- and C-blocks form spherical domains and the packing of these spheres can be controlled by changing the lengths of the middle and terminal B-blocks, self-assemble into various binary mesocrystals with space group symmetries of a large number of binary ionic crystals, including NaCl, CsCl, ZnS, ?-BN, AlB2, CaF2, TiO2, ReO3, Li3Bi, Nb3Sn(A15), and ?-Al2O3. This approach can be generalized to other terpolymers as well as to tetrapolymers to obtain ternary mesocrystals. Our study provides a new concept of macromolecular metallurgy for producing crystal phases in a mesoscale and thus makes multiblock copolymers a robust platform for the engineering of functional materials. PMID:24528160

Xie, Nan; Liu, Meijiao; Deng, Hanlin; Li, Weihua; Qiu, Feng; Shi, An-Chang

2014-02-26

289

Multiple feed powder splitter  

DOEpatents

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.

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

2001-01-01

290

Multiple feed powder splitter  

DOEpatents

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.

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

2002-01-01

291

Investigation of machining damage and tool wear resulting from drilling powder metal aluminum alloy  

SciTech Connect

This report documents the cutting of aluminum powder metallurgy (PM) parts for the North Carolina Manufacturing Extension Partnership. The parts, an aluminum powder metal formulation, were supplied by Sinter Metals Inc., of Conover, North Carolina. The intended use of the alloy is for automotive components. Machining tests were conducted at Y-12 in the machine shop of the Skills Demonstration Center in Building 9737. Testing was done on June 2 and June 3, 1997. The powder metal alloy tested is very abrasive and tends to wear craters and produce erosion effects on the chip washed face of the drills used. It also resulted in huge amounts of flank wear and degraded performance on the part of most drills. Anti-wear coatings on drills seemed to have an effect. Drills with the coating showed less wear for the same amount of cutting. The usefulness of coolants and lubricants in reducing tool wear and chipping/breakout was not investigated.

Fell, H.A. [Lockheed Martin Energy Systems, Inc., Oak Ridge, TN (United States)

1997-05-01

292

Low temperature fabrication from nano-size ceramic powders  

SciTech Connect

The objective of the compaction process is to produce a dense green-state compact from a nanosize powder that subsequently can be sintered at high temperatures to form a dense ceramic piece. High density in the green-state after pressing is of primary importance for achieving high densities after sintering. Investigation of the compaction behavior of ceramic powders, therefore, is an important part of characterization of raw ceramic powders and evaluation of their compaction behavior, analysis of interaction between particles, and the study of microstructure of green body (unsintered) during pressure-forming processes. The compaction of nanosize ceramic particles into high density green bodies is very difficult. For the nanosize materials used in this study (amorphous Si{sub 3}N{sub 4} and {gamma} Al{sub 2}O{sub 3}), there is no evidence by TEM of partial sintering after synthesis. Nevertheless, strong aggregation forces, such as the van der Waals surface forces of attraction, exist and result in moderate precursor particle agglomeration. More importantly, these attractive surface forces, which increase in magnitude with decreasing particle size, inhibit interparticle sliding necessary for particle rearrangement to denser bodies during subsequent compaction. Attempts to produce high density green body compacts of nanosize particles, therefore, generally have been focused on overcoming these surface forces of attraction by using either dispersive fluids or high pressures with or without lubricating liquids. In the present work, the use of high pressure has been employed as a means of compacting nanosize powders to relatively high green densities.

Gonzalez, E.J.; Piermarini, G.J.; Hockey, B. [and others

1995-06-01

293

Implications of elastic wave velocities for Apollo 17 rock powders  

NASA Technical Reports Server (NTRS)

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.

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

1974-01-01

294

Compact magnetograph  

NASA Technical Reports Server (NTRS)

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.

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

1982-01-01

295

PRESSURELESS SINTERED BERYLLIUM POWDER  

Microsoft Academic Search

A new process, termed pressureless sintering, has been established for ; the production of beryllium shapes (solid or hollow) to near theoretical density. ; It consists simply of the vacuum sintering at 1,200 deg C of loose powder of ; critical particle size distribution, without the application of pressure. ; Notable advantages are claimed over conventional powder production and ;

T. R. Barrett; G. C. Ellis; R. A. Knight

1959-01-01

296

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

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

Paris-Sud XI, Université de

297

Ti(C,N) cermets — Metallurgy and properties  

Microsoft Academic Search

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

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

1995-01-01

298

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

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

Laizhu Jiang; Hannu Hänninen; Jukka Paro; Veijo Kauppinen

1996-01-01

299

Particle size distribution and its relation to sintering --- A case study for UOâ powders  

Microsoft Academic Search

It is generally recognized that the particle size distribution (PSD) of powders plays a very significant role in powder compaction and sintering. However, particle size distribution data are generally presented in the form of one number (mean diameter). In the case of PSD data obtained by sedimentation, analysis of the whole curve reveals some interesting information. The type of information

R. C. Burk; P. S. Apte; T. W. Zawidzki

1983-01-01

300

Reaction synthesis of dynamically densified titanium-based intermetallic and ceramic-forming powders  

Microsoft Academic Search

The mechanism(s) and kinetics of the reaction synthesis of dynamically-densified Ti-based intermetallic and ceramic forming powder mixtures were investigated in this study. Dynamic densification employing shock-compression produces a dense-packed and highly-activated state of powder mixture constituents resulting in significantly increased mass transport rates and enhanced chemical reactivity. Green density compacts (˜85--95% TMD) of Ti-Si, Ti-B, and Ti-Al powder mixtures, obtained

Shantanu Ashok Namjoshi

1999-01-01

301

Pressureless sinterability of slip cast silicon nitride bodies prepared from coprecipitation-coated powders  

Microsoft Academic Search

The sinterability of compositions from different powder preparation methods (coprecipitation-coating of Si3N4 powder or mechanical mixing of Si3N4 with Y2O3 and Al2O3) and compaction routes (dry pressing or slip casting) was compared. Both the coating method and the slip casting process improved silicon nitride sinterability over the mechanical mixing method and dry pressing route. However, the minimisation of powder agglomeration

J Yang; F. J Oliveira; R. F Silva; J. M. F Ferreira

1999-01-01

302

SGC Tests for Influence of Material Composition on Compaction Characteristic of Asphalt Mixtures  

PubMed Central

Compaction characteristic of the surface layer asphalt mixture (13-type gradation mixture) was studied using Superpave gyratory compactor (SGC) simulative compaction tests. Based on analysis of densification curve of gyratory compaction, influence rules of the contents of mineral aggregates of all sizes and asphalt on compaction characteristic of asphalt mixtures were obtained. SGC Tests show that, for the mixture with a bigger content of asphalt, its density increases faster, that there is an optimal amount of fine aggregates for optimal compaction and that an appropriate amount of mineral powder will improve workability of mixtures, but overmuch mineral powder will make mixtures dry and hard. Conclusions based on SGC tests can provide basis for how to adjust material composition for improving compaction performance of asphalt mixtures, and for the designed asphalt mixture, its compaction performance can be predicted through these conclusions, which also contributes to the choice of compaction schemes. PMID:23818830

Chen, Qun

2013-01-01

303

SGC tests for influence of material composition on compaction characteristic of asphalt mixtures.  

PubMed

Compaction characteristic of the surface layer asphalt mixture (13-type gradation mixture) was studied using Superpave gyratory compactor (SGC) simulative compaction tests. Based on analysis of densification curve of gyratory compaction, influence rules of the contents of mineral aggregates of all sizes and asphalt on compaction characteristic of asphalt mixtures were obtained. SGC Tests show that, for the mixture with a bigger content of asphalt, its density increases faster, that there is an optimal amount of fine aggregates for optimal compaction and that an appropriate amount of mineral powder will improve workability of mixtures, but overmuch mineral powder will make mixtures dry and hard. Conclusions based on SGC tests can provide basis for how to adjust material composition for improving compaction performance of asphalt mixtures, and for the designed asphalt mixture, its compaction performance can be predicted through these conclusions, which also contributes to the choice of compaction schemes. PMID:23818830

Chen, Qun; Li, Yuzhi

2013-01-01

304

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...

305

Mystery Powder Investigation  

NSDL National Science Digital Library

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.

Rachel HallettNjuguna

2012-07-27

306

Gelcasting superalloy powders  

SciTech Connect

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.

Janney, M.A.

1995-12-31

307

Optimization of bond strength between gold alloy and porcelain through a composite interlayer obtained by powder metallurgy  

Microsoft Academic Search

The purpose of this study was to evaluate the influence of a composite interlayer (at the metal–ceramic interface) on the shear bond strength of a metal–ceramic composite when compared with a conventional porcelain fused to metal (PFM).Several metal–ceramic composites specimens were produced by hot pressing. To identify which was the best composition for the interlayer several composites, with different relations

B. Henriques; D. Soares; F. S. Silva

2011-01-01

308

High-strain-rate superplasticity at low temperature in a ZK61 magnesium alloy produced by powder metallurgy  

Microsoft Academic Search

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

Hiroyuki Watanabe; Toshiji Mukai; Mamoru Mabuchi; Kenji Higashi

1999-01-01

309

Effects of Thermocapillary Forces during Welding of 316L-Type Wrought, Cast and Powder Metallurgy Austenitic Stainless Steels  

Microsoft Academic Search

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

Stefano Sgobba; T Daniellou

2002-01-01

310

Hafnium powder production processes  

NASA Astrophysics Data System (ADS)

The conditions for the production of hafnium nanopowders via magnesium-thermic reduction of chlorides and the effect of these conditions on the phase composition and dispersion of the powders are studied analytical chemistry, X-ray diffractin, and electron microscopy. The results of phase and structural analysis of the powders, the results of microscopic studies, the measured specific surface, and the data of atomicemission analysis are presented.

Dzidziguri, E. L.; Salangina, E. A.; Sidorova, E. N.

2010-09-01

311

Compact spaces, compact cardinals, and elementary submodels  

Microsoft Academic Search

If M is an elementary submodel and X a topological space, then XM denotes the set X?M given the topology generated by the open subsets of X which are members of M. Call a compact space squashable iff for some M, XM is compact and XM?X. The first supercompact cardinal is the least ? such that all compact X with

Kenneth Kunen

2003-01-01

312

Exceptional Events Management Applied to Roller Compaction of Pharmaceutical Powders  

Microsoft Academic Search

Introduction  This study focuses on the development and implementation of an Exceptional Events Management (EEM) framework that detects,\\u000a diagnoses, and mitigates exceptional events inherent to particulate processes that are prevalent in the pharmaceutical industry.\\u000a \\u000a \\u000a \\u000a \\u000a Methods  The EEM framework combines several methods, including signed directed graph (SDG), qualitative trend analysis (QTA), and fast\\u000a Fourier transform analysis.\\u000a \\u000a \\u000a \\u000a \\u000a Results  We discuss the efficacy of the EEM

Intan Munirah Hamdan; Gintaras V. Reklaitis; Venkat Venkatasubramanian

2010-01-01

313

Intensive Pre-Incan Metallurgy Recorded by Lake Sediments from the Bolivian Andes  

Microsoft Academic Search

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

Mark B. Abbott; Alexander P. Wolfe

2003-01-01

314

Conversion of the under bump metallurgy into intermetallics: the impact on flip chip reliability  

Microsoft Academic Search

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

Frank Stepniak

2001-01-01

315

The Origins of Metallurgy: Distinguishing Stone from Metal Cut-marks on Bones from Archaeological Sites  

Microsoft Academic Search

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

Haskel J. Greenfield

1999-01-01

316

IDENTIFICATION OF TECHNOLOGY TREND ON INDONESIAN PATENT DOCUMENTS AND RESEARCH REPORTS ON CHEMISTRY AND METALLURGY FIELDS  

Microsoft Academic Search

The aims of this study are: to identify technology trends by identifying core topics, promi- nence topics, and emerging topics; and to assess the overlap between research and development and pat- ents on chemistry and metallurgy fields in Indonesia during 1993-1997. The technology trends are de- termined by measuring subject and keyword development on those fields. Co-words analysis is em-

ENDANG SRI; RUSMIYATI RAHAYU; ZAINAL A. HASIBUAN

2006-01-01

317

LASER WELDING -Literature Review Materials Science and Metallurgy Department, University of Cambridge, England. July 2002.  

E-print Network

LASER WELDING - Literature Review C.A. Walsh Materials Science and Metallurgy Department industry to produce seam or stitch welds, as alternatives to conventional resistance spot welding, which are used extensively for attaching auto-body panels to sub- assemblies. The advantages of laser welding

Cambridge, University of

318

Method for classifying ceramic powder  

NASA Technical Reports Server (NTRS)

Under the invented method, powder A of particles of less than 10 microns, and carrier powder B, whose average particle diameter is more than five times that of powder A, are premixed so that the powder is less than 40 wt.% of the total mixture, before classifying.

Takabe, K.

1983-01-01

319

Process for synthesizing compounds from elemental powders and product  

DOEpatents

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.

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

1993-12-14

320

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

NASA Technical Reports Server (NTRS)

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.

Bull, Jeffrey; Selvaduray, Guna; Leiser, Daniel

1992-01-01

321

Compact Reactor  

SciTech Connect

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.

Williams, Pharis E. [Williams Research, P.O. Box 554, Los Alamos, NM87544 (United States)

2007-01-30

322

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)

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.

Meschter, P. J.; Lederich, R. J.; Oneal, J. E.

1986-01-01

323

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

NASA Astrophysics Data System (ADS)

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.

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

2014-05-01

324

Ultrafine hydrogen storage powders  

DOEpatents

A method of making hydrogen storage powder resistant to fracture in service involves forming a melt having the appropriate composition for the hydrogen storage material, such, for example, LaNi.sub.5 and other AB.sub.5 type materials and AB.sub.5+x materials, where x is from about -2.5 to about +2.5, including x=0, and the melt is gas atomized under conditions of melt temperature and atomizing gas pressure to form generally spherical powder particles. The hydrogen storage powder exhibits improved chemcial homogeneity as a result of rapid solidfication from the melt and small particle size that is more resistant to microcracking during hydrogen absorption/desorption cycling. A hydrogen storage component, such as an electrode for a battery or electrochemical fuel cell, made from the gas atomized hydrogen storage material is resistant to hydrogen degradation upon hydrogen absorption/desorption that occurs for example, during charging/discharging of a battery. Such hydrogen storage components can be made by consolidating and optionally sintering the gas atomized hydrogen storage powder or alternately by shaping the gas atomized powder and a suitable binder to a desired configuration in a mold or die.

Anderson, Iver E. (Ames, IA); Ellis, Timothy W. (Doylestown, PA); Pecharsky, Vitalij K. (Ames, IA); Ting, Jason (Ames, IA); Terpstra, Robert (Ames, IA); Bowman, Robert C. (La Mesa, CA); Witham, Charles K. (Pasadena, CA); Fultz, Brent T. (Pasadena, CA); Bugga, Ratnakumar V. (Arcadia, CA)

2000-06-13

325

Whole powder pattern modelling.  

PubMed

A new approach for the modelling of diffraction patterns without using analytical profile functions is described and tested on ball milled f.c.c. Ni powder samples. The proposed whole powder pattern modelling (WPPM) procedure allows a one-step refinement of microstructure parameters by a direct modelling of the experimental pattern. Lattice parameter and defect content, expressed as dislocation density, outer cut-off radius, contrast factor, twin and deformation fault probabilities), can be refined together with the parameters (mean and variance) of a grain-size distribution. Different models for lattice distortions and domain size and shape can be tested to simulate or model diffraction data for systems as different as plastically deformed metals or finely dispersed crystalline powders. TEM pictures support the conclusions obtained by WPPM and confirm the validity of the proposed procedure. PMID:11832590

Scardi, P; Leoni, M

2002-03-01

326

Iowa Powder Atomization Technologies  

SciTech Connect

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.

None

2012-01-01

327

Demystifying Mystery Powders.  

ERIC Educational Resources Information Center

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)

Kotar, Michael

1989-01-01

328

Electrochemical synthesis using reactant-incorporated graphite powder electrodes: The reduction of p-dinitrobenzene in dilute aqueous acid  

Microsoft Academic Search

An approach to electro-organic synthesis has been developed using a composite or multiphase electrode where the solid, insoluble reactant is incorporated into a compacted powder electrode system. This has been achieved by intimately mixing the finely dispersed organic solid into a paste with graphite powder and an aqueous electrolyte. The paste was then spread between a graphite felt sandwich. A

R. H. Dahm; R. J. Latham; S. E. Mosley

1986-01-01

329

Iron-carbon compacts and process for making them  

DOEpatents

The present invention includes iron-carbon compacts and a process for making them. The process includes preparing a slurry comprising iron powder, furfuryl alcohol, and a polymerization catalyst for initiating the polymerization of the furfuryl alcohol into a resin, and heating the slurry to convert the alcohol into the resin. The resulting mixture is pressed into a green body and heated to form the iron-carbon compact. The compact can be used as, or machined into, a magnetic flux concentrator for an induction heating apparatus.

Sheinberg, Haskell (Santa Fe, NM)

2000-01-01

330

Method for synthesizing powder materials  

DOEpatents

A method for synthesizing ultrafine powder materials, for example, ceramic and metal powders, comprises admitting gaseous reactants from which the powder material is to be formed into a vacuum reaction chamber maintained at a pressure less than atmospheric and at a temperature less than about 400/degree/K (127/degree/C). The gaseous reactants are directed through a glow discharge provided in the vacuum reaction chamber to form the ultrafine powder material. 1 fig.

Buss, R.J.; Ho, P.

1988-01-21

331

Characterization of lead-free solders and under bump metallurgies for flip-chip package  

Microsoft Academic Search

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

Jong-Kai Lin; Ananda De Silva; Darrel Frear; Yifan Guo; Jin-Wook Jang; Li Li; D. Mitchell; B. Yeung; C. Zhang

2001-01-01

332

Characterization of lead-free solders and under bump metallurgies for flip-chip package  

Microsoft Academic Search

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

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

333

Contrasting lead speciation in forest and tilled soils heavily polluted by lead metallurgy  

Microsoft Academic Search

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

Vojt?ch Ettler; Aleš Van?k; Martin Mihaljevi?; Petr Bezdi?ka

2005-01-01

334

The Online Monitoring System in Wet Zinc Metallurgy Leaching Process Based on Fieldbus  

Microsoft Academic Search

The paper introduces the characteristics and functions of fieldbus technology through control of pH value in wet zinc metallurgy process. S7-300 PLC is master station, S7-200 PLC with communication module are secondary stations, and hardware configuration or software designing on profibus-DP are use of SETP7, monitoring software WinCC of master station monitor the system state and process data. So realize

Xianzhong He; Yanjie Guo

2009-01-01

335

Compact Spaces, Compact Cardinals, and Elementary Submodels  

E-print Network

Compact Spaces, Compact Cardinals, and Elementary Submodels #3; Kenneth Kunen yz July 11, 2002 Abstract If M is an elementary submodel and X a topological space, then XM denotes the set X \\M given than the #12;rst 1-extendible cardinal. 1 Introduction Elementary submodels were #12;rst used in set

Kunen, Ken

336

Accuracy in Powder Diffraction IV  

E-print Network

Accuracy in Powder Diffraction IV Program April 22-25, 2013 Photo credit ©2000 Robert Rathe #12;2 3 Accuracy in Powder Diffraction IV Program April 22-25, 2013 Day 1 | 22nd April Time Activity Chair 08 Introduction to program (Madsen, Cline) James Cline Ian Madsen 09:45 - 10:30 Accuracy in Powder Diffraction

Magee, Joseph W.

337

An Experimental Study of the Water Transfer Through Confined1 Compacted GMZ Bentonite2  

E-print Network

1 An Experimental Study of the Water Transfer Through Confined1 Compacted GMZ Bentonite2 3 W.M.Ye1 Intrusion Porosimetry (MIP) and Environmental Scanning Electron Microscope11 (ESEM) in different states: on oven-dried powder, bentonite slurry, as-compacted and12 wetted samples. It has been observed

Boyer, Edmond

338

Characterizing and modeling organic binder burnout from green ceramic compacts  

SciTech Connect

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.

Ewsuk, K.G.; Cesarano, J. III; Cochran, R.J.; Blackwell, B.F.; Adkins, D.R.

1995-09-01

339

Synthesis and characterization of carbon nanotubes over iron carbide nanoparticles coated Al powder using thermal chemical vapor deposition  

NASA Astrophysics Data System (ADS)

A simple method is described to synthesize carbon nanotubes (CNTs) by the thermal decomposition of toluene at 750°C over a thin catalyst film deposited on Al powder. This method allows the bulk metal surface to act as both the catalyst and support for CNT growth. The catalyst film on Al was prepared from an ethanol solution of iron nitrate. Under the growth conditions, iron nitrate formed an amorphous iron oxide layer that transform into crystalline Fe2O3, which was further reduced to Fe3O4 and Fe3C. It is believed that the growth of CNTs took place on iron carbide nanoparticles that were formed from FeO. The characterization of CNTs was mainly carried out by powder X-ray diffraction and scanning electron microscopy, X-ray fluorescence and thermogravimatric analysis. The CNTs were found to be highly dispersed in Al powder. This composite powder could be further used for the fabrication of Al matrix composites using powder metallurgy process in which the powder were first cold pressed at 500-550 MPa followed by sintering at 620°C for 2 h under a vacuum of 10-2 torr. The mechanical properties of the sintered composites were measured using a microhardness tester and a Universal testing Instron machine.

Singhal, S. K.; Seth, R. K.; Rashmi; Teotia, Satish; Mamta; Chahal, Rajeev; Mathur, R. B.

2013-02-01

340

*Correspondence to: Zbigniew Galias, Department of Electrical Engineering, University of Mining and Metallurgy, al. Mickiewicza 30, 30-059 KrakoH w, Poland.  

E-print Network

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

Galias, Zbigniew

341

Analysis of cold and hot isostatic compaction of spherical particles  

SciTech Connect

Cold and hot isostatic compaction of monosized metal powders is analyzed within the framework of viscoplastic theory for particles packed both in a regular and a random manner. The problem of local contact between spherical particles is analyzed first by drawing upon recent detailed numerical studies of spherical indentation of power law plastic and creeping solids. The compaction process is then modelled as a self-similar contraction of unit (average) cells, in contrast to commonly used phenomenological assumptions, yielding a simple but rigorous relation between the densification density and center-to-center approach of adjacent powder particles. The resulting densification formulae are easy to apply and the influence of hardening and creep parameters appears in concise form. Predictions are compared with discriminating experimental data for a variety of different powder materials, both in the cold and a hot state, and the agreement is good for a relative density increase of up to 30%.

Larsson, P.L.; Biwa, S.; Storaakers, B. [Royal Inst. of Tech., Stockholm (Sweden). Dept. of Solid Mechanics] [Royal Inst. of Tech., Stockholm (Sweden). Dept. of Solid Mechanics

1996-09-01

342

Counterintuitive compaction behavior of clopidogrel bisulfate polymorphs.  

PubMed

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

Khomane, Kailas S; More, Parth K; Bansal, Arvind K

2012-07-01

343

Titanium Sheet Fabricated from Powder for Industrial Applications  

SciTech Connect

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.

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

344

Silicon nitride/silicon carbide composite powders  

DOEpatents

Prepare silicon nitride-silicon carbide composite powders by carbothermal reduction of crystalline silica powder, carbon powder and, optionally, crystalline silicon nitride powder. The crystalline silicon carbide portion of the composite powders has a mean number diameter less than about 700 nanometers and contains nitrogen. The composite powders may be used to prepare sintered ceramic bodies and self-reinforced silicon nitride ceramic bodies.

Dunmead, Stephen D. (Midland, MI); Weimer, Alan W. (Midland, MI); Carroll, Daniel F. (Midland, MI); Eisman, Glenn A. (Midland, MI); Cochran, Gene A. (Midland, MI); Susnitzky, David W. (Midland, MI); Beaman, Donald R. (Midland, MI); Nilsen, Kevin J. (Midland, MI)

1996-06-11

345

Process design applied to optimise a directly compressible powder produced via a continuous manufacturing process  

Microsoft Academic Search

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

Y. Gonnissen; S. I. V. Gonçalves; B. G. De Geest; J. P. Remon; C. Vervaet

2008-01-01

346

Laboratory production of zirconium carbide compacts for use in inert matrix fuels  

NASA Astrophysics Data System (ADS)

Zirconium carbide is being actively considered for use as an inert matrix material in composite nuclear fuel for gas-cooled fast reactors. ZrC can be produced either by the endothermic carbothermal reduction of zirconium dioxide or by the direct exothermic reaction of pure zirconium and graphite powder mixtures. The exothermic reaction is classified as combustion synthesis or self heating synthesis. Experiments were conducted to demonstrate the combustion synthesis reaction of zirconium and graphite powders and measure the ignition and adiabatic temperatures. The heat released during this short reaction time was sufficient only to partially sinter the compacts to less than 40% theoretical density. Subsequently, compacts of ZrC were similarly produced by combustion synthesis followed by a short, high temperature hold at 2440 °C to relieve residual stresses in the compacts following the rapid reaction sintering. External pressures of up to 5.2 MPa were used as an additional driving force for sintering. The effects of reactant particle size and degree of uniaxial pressing on the product density and porosity were also studied. Higher densities in the fabricated compacts were noted for higher uniaxial pressures irrespective of powder size. Also, smaller powder sizes produced compacts up to 92% TD, while larger particle sizes produced compacts up to 84% TD for the same pressure. The compacts were characterized based on composition, microstructure, and density/porosity. Results of the different experiments are presented.

Vasudevamurthy, Gokul; Knight, Travis W.; Roberts, Elwyn; Adams, Thad M.

2008-02-01

347

Investigation of Soap Powders  

E-print Network

.42%* HagCOa 71.52%* Total 98T 5 Sopade. Manufactured by James Pyle & Company, Hew York, H. Y. Wt. ya£ Price 5 cents. Analysis• Moisture 26 .23$ HaaHPO* 1 8 . 1 7 * NaaCOa 5 S . 3 2 J Total 99.72% Rub Ho More* Manufactured by Summit City Soap... 98.16$ Gold Dust Washing Powder. Manufactured by N. K. Fairbanks Company. Wt. 3/4 pound Price 5 cents. Analysis. Moisture 14.79$ Soap 35.02$ Na 2C0 a 49.10$ Total 98.91$ Star Naphtha. Manufactured by Proctor & Gamble, Kansas City Wt. 1...

Bragg, G.A.

1913-01-01

348

Multipass equal channel angular extrusion of MgB 2 powder in tubes  

NASA Astrophysics Data System (ADS)

In the current study multipass equal channel angular extrusion (ECAE) is adopted for the first time to study the applicability of the process to compact magnesium boride (MgB 2) powder in tubes (PITs). The influence of number of ECAE passes on MgB 2 PITs was also analyzed in terms of microstructure, density and mechanical properties. MgB 2 PITs with iron tube were processed up to six ECAE passes. X-ray analysis of the compacts showed no other phases, other than MgO, in MgB 2 compacts even after large mechanical working and annealing. Simple shear stresses predominant in ECAE constantly rendered compaction of the hard brittle MgB 2 powders.

Nagasekhar, A. V.; Tick-Hon, Yip; Guduru, R. K.; Ramakanth, K. S.

2007-11-01

349

Development Status of a CVD System to Deposit Tungsten onto UO2 Powder via the WCI6 Process  

NASA Technical Reports Server (NTRS)

Nuclear Thermal Propulsion (NTP) is under development for deep space exploration. NTP's high specific impulse (> 850 second) enables a large range of destinations, shorter trip durations, and improved reliability. W-60vol%UO2 CERMET fuel development efforts emphasize fabrication, performance testing and process optimization to meet service life requirements. Fuel elements must be able to survive operation in excess of 2850 K, exposure to flowing hydrogen (H2), vibration, acoustic, and radiation conditions. CTE mismatch between W and UO2 result in high thermal stresses and lead to mechanical failure as a result UO2 reduction by hot hydrogen (H2) [1]. Improved powder metallurgy fabrication process control and mitigated fuel loss can be attained by coating UO2 starting powders within a layer of high density tungsten [2]. This paper discusses the advances of a fluidized bed chemical vapor deposition (CVD) system that utilizes the H2-WCl6 reduction process.

Mireles, O. R.; Kimberlin, A.; Broadway, J.; Hickman, R.

2014-01-01

350

Phase transformations in shock compacted magnetic materials  

NASA Astrophysics Data System (ADS)

Shock compaction experiments were performed on soft magnetic phases Fe 4N and Fe16N2, and hard magnetic phases Nd 2Fe14B and Sm2Fe17N3 in order to determine their thermo-mechanical stability during shock loading and explore the possibility of fabricating a textured nanocomposite magnet. Gas gun experiments performed on powders pressed in a three capsule fixture showed phase transformations occurring in Fe4N, Fe16N 2, and Nd2Fe14B, while Sm2Fe17 N3 was observed to be relatively stable. Shock compaction of FCC Fe4N resulted in a partial transformation to HCP Fe3N, consistent with previous reports of the transition occurring at a static pressure of ~3 GPa. Shock compaction of Fe16N 2 produced decomposition products ?-Fe, Fe4N, and FeN due to a combination of thermal effects associated with dynamic void collapse and plastic deformation. Decomposition of Nd-Fe-B, producing ?-Fe and amorphous Nd-Fe-B, was observed in several shock consolidated samples and is attributed to deformation associated with shock compaction, similar to decomposition reported in ball milled Nd-Fe-B. No decomposition was observed in shock compacted samples of Sm-Fe-N, which is consistent with literature reports showing decomposition occurring only in samples compacted at a pressure above ~15 GPa. Nd-Fe-B and Sm-Fe-N were shown to accommodate deformation primarily by grain size reduction, especially in large grained materials. Hard/Soft composite magnetic materials were formed by mixing single crystal particles of Nd-Fe-B with iron nanoparticles, and the alignment-by-magnetic-field technique was able to introduce significant texture into green compacts of this mixture. While problems with decomposition of the Nd2Fe14B phase prevented fabricating bulk magnets from the aligned green compacts, retention of the nanoscale morphology of the ?-Fe particles and the high alignment of the green compacts shows promise for future development of textured nanocomposite magnets through shock compaction.

Wehrenberg, Christopher

351

Parametric Powder Diffraction  

NASA Astrophysics Data System (ADS)

The rapidity with which powder diffraction data may be collected, not only at neutron and X-ray synchrotron facilities but also in the laboratory, means that the collection of a single diffraction pattern is now the exception rather than the rule. Many experiments involve the collection of hundreds and perhaps many thousands of datasets where a parameter such as temperature or pressure is varied or where time is the variable and life-cycle, synthesis or decomposition processes are monitored or three-dimensional space is scanned and the three-dimensional internal structure of an object is elucidated. In this paper, the origins of parametric diffraction are discussed and the techniques and challenges of parametric powder diffraction analysis are presented. The first parametric measurements were performed around 50 years ago with the development of a modified Guinier camera but it was the automation afforded by neutron diffraction combined with increases in computer speed and memory that established parametric diffraction on a strong footing initially at the ILL, Grenoble in France. The theoretical parameterisation of quantities such as lattice constants and atomic displacement parameters will be discussed and selected examples of parametric diffraction over the past 20 years will be reviewed that highlight the power of the technique.

David, William I. F.; Evans, John S. O.

352

Explosive Compations of Intermetallic-Forming Powder Mixtures for Fabricating Structural Energetic Materials  

Microsoft Academic Search

A double-tube implosion geometry is used to explosively shock consolidate intermetallic-forming Ni-Al, Ta-Al, Nb-Al, Mo-Al and W-Al powder mixtures for fabricating bulk structural energetic materials, with mechanical strength and ability to undergo impact-initiated exothermic reactions. The compacts are characterized based on uniformity of micro structure and degree of densification. Mechanical properties of the compacts are characterized over the strain-rate range

S. W. Du; B. Aydelotte; D. Fondse; C.-T. Wei; F. Jiang; E. Herbold; K. Vecchio; M. A. Meyers; N. N. Thadhani

2009-01-01

353

Effect of repeated compaction of tablets on tablet properties and work of compaction using an instrumented laboratory tablet press.  

PubMed

Abstract 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

Gamlen, Michael John Desmond; Martini, Luigi G; Al Obaidy, Kais G

2015-01-01

354

The Effects of Processing Parameters on Microstructure and Properties of Laser Deposited PM Alloy 690N{sub 2} Powder  

SciTech Connect

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.

J.W. Sears

2002-04-05

355

Bend strengths of reaction bonded silicon nitride prepared from dry attrition milled silicon powder  

NASA Technical Reports Server (NTRS)

Dry attrition milled silicon powder was compacted, sintered in helium, and reaction bonded in nitrogen-4 volume percent hydrogen. Bend strengths of bars with as-nitrided surfaces averaged as high as 210 MPa at room temperature and 220 MPa at 1400 C. Bars prepared from the milled powder were stronger than those prepared from as-received powder at both room temperature and at 1400 C. Room temperature strength decreased with increased milling time and 1400 C strength increased with increased milling time.

Herbell, T. P.; Glasgow, T. K.

1979-01-01

356

Eutectic Sn\\/Pb solder bump and under bump metallurgy: interfacial reactions and adhesion  

Microsoft Academic Search

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

Se-Young Jang; Kyung-Wook Paik

1998-01-01

357

Compaction Behavior of Isomalt after Roll Compaction  

PubMed Central

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

Quodbach, Julian; Mosig, Johanna; Kleinebudde, Peter

2012-01-01

358

Compaction behavior of isomalt after roll compaction.  

PubMed

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

Quodbach, Julian; Mosig, Johanna; Kleinebudde, Peter

2012-01-01

359

Gas-Phase Combustion Synthesis of Aluminum Nitride Powder  

NASA Technical Reports Server (NTRS)

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.

Axelbaum, R. L.; Lottes, C. R.; Huertas, J. I.; Rosen, L. J.

1996-01-01

360

Three-dimensional simulations of nanopowder compaction processes by granular dynamics method.  

PubMed

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

Boltachev, G Sh; Lukyashin, K E; Shitov, V A; Volkov, N B

2013-07-01

361

Elaboration of metallic compacts with high porosity for mechanical supports of SOFC  

NASA Astrophysics Data System (ADS)

The development of third generation Solid Oxide Fuel Cells (SOFC) with metallic mechanical supports presents several advantages over that of ceramic stacks by offering a lower cost and longer lifetime of the stacks. As a consequence, it is necessary to prepare metallic porous compacts that remain stable at the operating temperature of the SOFC (700-800 °C) under reductive atmosphere. This paper presents an innovative process to elaborate iron, nickel and cobalt porous compacts. The process is based on the thermal decomposition of metal oxalate precursors with controlled morphology into metallic powders with coralline shape. Uniaxial compaction of such powders (without binder addition to the powders) under low uniaxial pressures (rising from 20 to 100 MPa) gave rise to green compacts with high porosity and good mechanical properties. After annealing at 800 °C under H 2 atmosphere, the compacts still present interconnected porosity high enough to allow sufficient gas flow to feed a SOFC single cell in hydrogen: the porosity rises from 25 to 50% for iron compacts, from 20 to 50% for cobalt compacts, and is higher than 40% for nickel compacts. Results from physicochemical characterization (XRD, SEM, gas permeation, Hg porosimetry) corroborated the process for SOFC application.

Panteix, P. J.; Baco-Carles, V.; Tailhades, Ph.; Rieu, M.; Lenormand, P.; Ansart, F.; Fontaine, M. L.

2009-02-01

362

Finite Element Analysis of Compressible Viscoplasticity  

E-print Network

, a finite element model has been formulated to simulate the hot forging stage in powder metallurgy of uniaxial free compaction and applied to the hot forging of an automotive connecting rod preform. Keywords process is outlined as follows: - Mixing of powder with some binder-lubricant. - Cold compaction step

Paris-Sud XI, Université de

363

Characterization of commercially pure aluminum powder for research reactor fuel plates  

SciTech Connect

Aluminum powder is used as the matrix material in the production of uranium aluminide, oxide, and silicide dispersion fuel plates for research and test reactors. variability in the characteristics of the aluminum powder, such as moisture content and particle-size distribution, influences blending and compacting of the aluminum/fuel powder. A detailed study was performed to characterize the physical properties of three aluminum powder lots. An angle-of-shear test was devised to characterize the cohesiveness of the aluminum powder. Flow-rate measurements, apparent density determination, subsieve analysis, surface area measurements, and scanning electron microscopy were also used in the study. It was found that because of the various types of commercially available powders, proper specification of powder variables will ensure the receipt of consistent raw materials. Improved control of the initial powder will reduce the variability of fuel-plate production and will improve overall plate reproducibility. It is recommended that a standard specification be written for the aluminum powder and silicide fuel.

Downs, V.D. (Babcock and Wilcox Co., Lynchburg, VA (United States)); Wiencek, T.C. (Argonne National Lab., IL (United States))

1992-01-01

364

Characterization of commercially pure aluminum powder for research reactor fuel plates  

SciTech Connect

Aluminum powder is used as the matrix material in the production of uranium aluminide, oxide, and silicide dispersion fuel plates for research and test reactors. variability in the characteristics of the aluminum powder, such as moisture content and particle-size distribution, influences blending and compacting of the aluminum/fuel powder. A detailed study was performed to characterize the physical properties of three aluminum powder lots. An angle-of-shear test was devised to characterize the cohesiveness of the aluminum powder. Flow-rate measurements, apparent density determination, subsieve analysis, surface area measurements, and scanning electron microscopy were also used in the study. It was found that because of the various types of commercially available powders, proper specification of powder variables will ensure the receipt of consistent raw materials. Improved control of the initial powder will reduce the variability of fuel-plate production and will improve overall plate reproducibility. It is recommended that a standard specification be written for the aluminum powder and silicide fuel.

Downs, V.D. [Babcock and Wilcox Co., Lynchburg, VA (United States); Wiencek, T.C. [Argonne National Lab., IL (United States)

1992-11-01

365

Improving The Making Of Powder Of RE-Si Ferroalloy Using High-Speed Photographic Technology  

NASA Astrophysics Data System (ADS)

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.

Jia, Dayoung; Liu, Chunsheng

1990-01-01

366

Carboxymethylation of Tamarind kernel powder  

Microsoft Academic Search

Tamarind kernel powder is a rich source of xyloglucan gum. The gum can be utilized in a number of industries. With a view to utilize the gum for broader applications, carboxymethylation of tamarind kernel powder was carried out. The reaction conditions were optimized with respect to concentration of sodium hydroxide, monochloroacetic acid, solvent ratio, reaction time, and reaction temperature. Carboxymethylation

Puja Goyal; Vineet Kumar; Pradeep Sharma

2007-01-01

367

21 CFR 520.1696a - Buffered penicillin powder, penicillin powder with buffered aqueous diluent.  

Code of Federal Regulations, 2011 CFR

...2011-04-01 2011-04-01 false Buffered penicillin powder, penicillin powder with buffered aqueous diluent. 520...FORM NEW ANIMAL DRUGS § 520.1696a Buffered penicillin powder, penicillin powder with buffered...

2011-04-01

368

21 CFR 520.1696a - Buffered penicillin powder, penicillin powder with buffered aqueous diluent.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false Buffered penicillin powder, penicillin powder with buffered aqueous diluent. 520...FORM NEW ANIMAL DRUGS § 520.1696a Buffered penicillin powder, penicillin powder with buffered...

2010-04-01

369

21 CFR 520.1696a - Buffered penicillin powder, penicillin powder with buffered aqueous diluent.  

Code of Federal Regulations, 2012 CFR

...2012-04-01 2012-04-01 false Buffered penicillin powder, penicillin powder with buffered aqueous diluent. 520...FORM NEW ANIMAL DRUGS § 520.1696a Buffered penicillin powder, penicillin powder with buffered...

2012-04-01

370

Compact Propositional Gödel Logics  

Microsoft Academic Search

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

Matthias Baaz; Richard Zach

1998-01-01

371

Compaction properties of isomalt  

Microsoft Academic Search

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

Gerad K. Bolhuis; Jeffrey J. P. Engelhart; Anko C. Eissens

2009-01-01

372

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...

373

Etude des proprietes mecaniques statiques et dynamiques de pieces d'acier elaborees par metallurgie des poudres  

NASA Astrophysics Data System (ADS)

The main objective of this thesis ais to gain a better understanding of the effects of processing variables on the porosity and microstructure of powder metallurgy (P/M) steel and their effect on mechanical properties, both static and dynamic. The effects of processing variables on porosity and microstructure were evaluated by advanced microstructural characterization using both optical and electron microscopies. Then the impacts of porosity and microstructure on both static and dynamic properties were measured. Static mechanical properties were characterized by hardness measurements and by tensile tests while fatigue testing was used for evaluating dynamic properties. Fractographic observations were made on tensile and fatigue fracture samples to correlate the microstructural features to the mechanical performance of P/M steels. The experimental work covered in this Ph.D. thesis enables to further understand the mechanisms by which process variables affect the microstructure and the mechanical properties of samples. In the first paper, the effect of prealloying MnS up to 1.0 wt pct on the microstructural features of non-metallic inclusions and their impact on tensile and fatigue properties of a 7.0 g/cm3 P/M steel (Fe-2.0Cu-0.7C) have been investigated. As the MnS content increases, larger, more irregular and more closely spaced inclusions are obtained. Whilst no significant impact on both static and dynamic properties was observed when prealloying up to 0.65 wt pct MnS, a decrease of more than 15 pct of the ultimate tensile strength and of the endurance limit was found when the MnS content reaches 1.0 wt pct. The decrease in the ultimate tensile strength is attributed to a lower ductility of the sinternecks, as void initiation and void growth were promoted at lower stress levels by larger inclusions. The larger size of the MnS particles and the lower mean free path between non-metallic inclusions also favor microcrack initiation and their coalescence into cracks, leading to premature fatigue fracture. In the second paper, the improvement of performance that can be achieved by copper infiltration was quantified. Tensile and fatigue properties of a Fe-2.0Cu-0.7C PM steel were compared to the same alloy infiltrated with 8 wt-% copper. Microstructural characterization, using optical and electron microscopies, was carried out to understand the effect of copper infiltration on mechanical properties. Copper infiltration improves the ultimate tensile strength by 40% by increasing the load bearing section, decreasing the stress concentrations associated to open porosity and increasing the hardness of the steel matrix. Fractographic observations show the evidence of stress transmission from the sinternecks to the steel particles due to infiltrated copper. The beneficial effect of copper infiltration is less pronounced for fatigue properties as the endurance limit is increased by only 10%. This lower improvement is explained by crack initiation at the copper/steel matrix interface. In the last paper, the microstructural characterization of nickel rich areas and their influence on the endurance limit of a P/M steel was investigated. The addition of nickel powder to a P/M steel increases hardenability, enabling the formation of martensite directly after the sintering process. However, the slow diffusion rate of nickel into iron leads to the formation of nickel rich areas (NRA). Two steel alloys were studied, the first one is a Fe-6.4Ni-0.7Mo-0.7C with standard size nickel powder additions and the second one is a Fe-2.4-0.7Mo-0.7C where a finer size nickel powder was added. The influence of the size of the nickel powder used on hardenability and on the presence of NRA has been investigated by optical microscopy. A complete identification of the microstructural constituents and the effect of nickel concentration on their presence were achieved using X-ray energy dispersive spectrometry and electron diffraction in the transmission electron microscope. Results obtained by these techniques show the presence of austenite and martensite.

Bernier, Fabrice

374

The effect of fly ash and limestone fillers on the viscosity and compressive strength of self-compacting repair mortars  

Microsoft Academic Search

Today, self-compacting mortars are preferred for repair purposes due to the application easiness and mechanical advantages. However, for self-compactability, the paste phase must meet some certain criteria at fresh state. The cement as well as the ingredients of the paste, powders with cementitious, pozzolanic or inert nature and plasticizing chemical admixtures should be carefully chosen in order to obtain a

Burak Feleko?lu; Kamile Tosun; Bülent Baradan; Ak?n Altun; Bahad?r Uyulgan

2006-01-01

375

Preparation of superconductor precursor powders  

DOEpatents

A process for the preparation of a precursor metallic powder composition for use in the subsequent formation of a superconductor. The process comprises the steps of providing an electrodeposition bath comprising an electrolyte medium and a cathode substrate electrode, and providing to the bath one or more soluble salts of one or more respective metals, such as nitrate salts of thallium, barium, calcium, and copper, which are capable of exhibiting superconductor properties upon subsequent appropriate treatment. The bath is continually energized to cause the metallic particles formed at the electrode to drop as a powder from the electrode into the bath, and this powder, which is a precursor powder for superconductor production, is recovered from the bath for subsequent treatment. The process permits direct inclusion of thallium in the preparation of the precursor powder, and yields an amorphous product mixed on an atomic scale to thereby impart inherent high reactivity. Superconductors which can be formed from the precursor powder include pellet and powder-in-tube products.

Bhattacharya, Raghunath (Littleton, CO); Blaugher, Richard D. (Evergreen, CO)

1995-01-01

376

Laboratory compaction of cohesionless sands  

E-print Network

on the maximum dry unit weight during compaction. Three different laboratory compaction methods were used: 1) Standard Proctor', 2) Modified Proctor; and 3) Vibrating hammer. The effects of the grain size distribution, particle shape and laboratory compaction...

Delphia, John Girard

2012-06-07

377

powder in water  

NASA Astrophysics Data System (ADS)

Submicron-sized NiAl2+ X O4 fragments and nanocondensates of Ni-doped ?-Al2O3, Al-doped NiO and ?-Ni(OH)2 were synthesized simultaneously by pulsed laser ablation of NiAl2O4 powder in water and characterized using X-ray/electron diffraction and optical spectroscopy. The NiAl2+ X O4 is Al-enriched spinel with dislocations and subgrains. The Ni-doped ?-Al2O3 spinel has paracrystalline distribution (i.e., with fair constant longitudinal spacing, but variable relative lateral translations) of defect clusters and intimate intergrowth of ?-Al2O3 and 2x(3) commensurate superstructure. The Al-doped NiO has perfect cubo-octahedron shape and as small as 5 nm in size. The ?-Ni(OH)2 and 1-D turbostratic hydroxide lamellae occurred as a matrix of these oxide nanoparticles. The colloidal suspension containing the composite phases has a minimum band gap of 5.3 eV for potential photocatalytic applications.

Chan, Ya-Ting; Wu, Chao-Hsien; Shen, Pouyan; Chen, Shuei-Yuan

2014-09-01

378

JOURNALDEPHYSIQUE IV ColloqueC7,supplkmentauJournaldePhysique111,Volume3, novembre1993  

E-print Network

and Metallurgy, Dept. of Metal Forming and Physical Metallurgy of Non-Ferrous Metals,Al. Mickiewicza30, 30 of sintered preforms, prepared on the basis of powder metallurgy. Forming of powder metallurgy parts

Boyer, Edmond

379

Silica powders for powder evacuated thermal insulating panel and method  

DOEpatents

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 tetraakyl 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.

Harris, Michael T. (Knoxville, TN); Basaran, Osman A. (Oak Ridge, TN); Kollie, Thomas G. (Oak Ridge, TN); Weaver, Fred J. (Knoxville, TN)

1994-01-01

380

Silica powders for powder evacuated thermal insulating panel and method  

DOEpatents

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 tetraakyl 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.

Harris, Michael T. (Knoxville, TN); Basaran, Osman A. (Oak Ridge, TN); Kollie, Thomas G. (Oak Ridge, TN); Weaver, Fred J. (Knoxville, TN)

1995-01-01

381

Silica powders for powder evacuated thermal insulating panel and method  

DOEpatents

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 tetraakyl 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.

Harris, Michael T. (Knoxville, TN); Basaran, Osman A. (Oak Ridge, TN); Kollie, Thomas G. (Oak Ridge, TN); Weaver, Fred J. (Knoxville, TN)

1996-01-01

382

Silica powders for powder evacuated thermal insulating panel and method  

DOEpatents

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.

Harris, M.T.; Basaran, O.A.; Kollie, T.G.; Weaver, F.J.

1996-01-02

383

Self-Paced Tutorial Courses for Mineral Science - Metallurgy Departments. Final Progress Report (July 1975-August 1980).  

ERIC Educational Resources Information Center

Four courses in extractive metallurgy (Pyrometallurgy, Hydrometallurgy, Electrometallurgy; and Physical Chemistry of Iron and Steel) were prepared in a modular, self-paced format. Development of the course materials included: (1) preparation of course outlines by unit coordinators and advisory committees; (2) approval of course outlines (included…

Twidwell, L. G.

384

B.G. Thomas, "Continuous Casting", Yearbook of Science and Technology, McGraw-Hill, 2004. 1 Continuous Casting (metallurgy)  

E-print Network

B.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 at Urbana-Champaign 217-333-6919; bgthomas@uiuc.edu Continuous casting is used to mass produce basic metals

Thomas, Brian G.

385

Mounting of high power laser diodes on boron nitride heat sinks using an optimized Au\\/Sn metallurgy  

Microsoft Academic Search

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

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

386

Method for molding ceramic powders  

DOEpatents

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.

Janney, M.A.

1990-01-16

387

Method for molding ceramic powders  

DOEpatents

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, whereafter the product may be sintered.

Janney, Mark A. (Knoxville, TN)

1990-01-01

388

Shock Wave Processing of Metal Powders and their Micro-structural Characterization  

NASA Astrophysics Data System (ADS)

Shock wave processing has been employed to compact the metal powders nearer to their theoretical value with negligible density gradient. Cylindrical geometry and Explosive die pellet press geomet ry configuring the various critical parameters with optimized detonation pressure are used for the compaction and are investigated spectroscopically. The post-compacts are analyzed for structural phase, particle size variation, surface morphology, core micro-structure, micro-hardness and density. Cylindrical compaction system with moderate detonation velocity (4.2 km/s) corresponding to detonation pressure of 4.5 GPa leads to the formation of compacts with density more than 95% theoretical, higher micro-hardness (112±6)Hv and lesser inter-particle melting content.

Sharma, Akash Deep; Sharma, A. K.; Thakur, Nagesh

2011-12-01

389

Compaction of AWBA fuel pellets without binders (AWBA Development Program)  

SciTech Connect

Highly active oxide fuel powders, composed of UO/sub 2/, UO/sub 2/-ThO/sub 2/, or ThO/sub 2/, were compacted into ultra-high density pellets without the use of binders. The objective of the study was to select the optimum die lubricant for compacting these powders into pellets in preparation for sintering to densities in excess of 97% Theoretical Density. The results showed that sintered density was a function of both the lubricant bulk density and concentration with the lowest bulk density lubricant giving the highest sintered densities with a lubricant concentration of 0.1 weight percent. Five calcium and zinc stearates were evaluated with a calcium stearate with a 15 lb/ft/sup 3/ bulk density being the best lubricant.

Johnson, R.G.R.

1982-08-01

390

Improved blend and tablet properties of fine pharmaceutical powders via dry particle coating.  

PubMed

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

Huang, Zhonghui; Scicolone, James V; Han, Xi; Davé, Rajesh N

2015-01-30

391

Temperature kinetics during shock-wave consolidation of metallic powders  

SciTech Connect

Powders (60 ..mu..m diam) of constantan and pure copper were compressed statically into cylindrical greens (20.3 mm diam, 5.3 mm long) with a flat interface separating the two powders. A 20-mm propellant gun was used to accelerate a flyer of Lexan, copper, or aluminum, and generate in the green a shock wave with front parallel to the Cu/constantan interface. The voltages between opposite ends of the greens were measured as a function of time and for shock pressures between 1.3 and 9.4 GPa. When the shock wave arrives at the Cu/constantan interface, the voltage signal shows an abrupt increase, which lasts between 45 and 81 ns and leads to a peak temperature T/sub p/. After this, the hotter and cooler parts of the compact equilibrate and the temperature decreases to a value T/sub h/. With increasing shock pressure, T/sub h/ increases from 425 to 1215 K. The measurements of T/sub h/ are in excellent agreement with the temperatures calculated from the measured flyer velocity, the Hugoniot for copper powder, and thermodynamic data for the flyer and powders.

Schwarz, R.B.; Kasiraj, P.; Vreeland, T. Jr.

1985-01-01

392

Rotary powder feed through apparatus  

DOEpatents

A device for increasing the uniformity of solids within a solids fabrication system, such as a direct light fabrication (DLF) system in which gas entrained powders are passed through the focal point of a moving high-power light which fuses the particles in the powder to a surface being built up in layers. The invention provides a feed through interface wherein gas entrained powders input from stationary input lines are coupled to a rotating head of the fabrication system. The invention eliminates the need to provide additional slack in the feed lines to accommodate head rotation, and therefore reduces feed line bending movements which induce non-uniform feeding of gas entrained powder to a rotating head.

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

2001-01-01

393

Shock compression of quartz and aluminum powder mixtures  

SciTech Connect

The authors report about the shock-compression response of highly porous (55% and 65% dense) mixtures of 4Al + 3SiO{sub 2} powders having shock-induced phase transitions and chemical reactions. Shock recovery experiments were performed using the CETR/Sawaoka plate-impact system (P = 40 to 100 GPa) and the Sandia Momma Bear A Comp B fixture (P = 22 to 45 GPa). The recovered compacts contained the high pressure stishovite phase, products of chemical reaction, as well as unreacted constituents. The reaction products formed included Al{sub 2}O{sub 3} metallic Si (ambient and high pressure phases), SiAl intermetallic, and kyanite (Al{sub 2}SiO{sub 5}). The shock-induced chemical reaction in 4Al + 3SiO{sub 2} powder mixtures, appears to have been accompanied (or assisted) by the formation of stishovite, a high pressure phase of quartz.

Joshi, V.S. [New Mexico Tech, Socorro, NM (United States). Energetic Materials Research and Testing Center; Thadhani, N.N. [Georgia Inst. of Tech., Atlanta, GA (United States). School of Materials Science and Engineering; Graham, R.A.; Holman, G.T. Jr. [Sandia National Labs., Albuquerque, NM (United States). Advanced Materials Physics and Devices

1995-11-01

394

Gas release from a compact powdery sample ion source  

Microsoft Academic Search

The species and the quantities of gases released during the operation of a compact powdery sample ion source were investigated. During the initial heating of the filament, H2O was emitted from the powder and its partial pressure occupied more than 90% of the total pressure. Neither LiH nor LiN3, emitted detectable amount of Li. Atomic and molecular nitrogens were found

Motoi Wada; Toshiro Kasuya; Mamiko Sasao; H. Kawano

1999-01-01

395

Analysis of localized microstructural changes in dynamically consolidated metal powders. [AL-6% Si  

SciTech Connect

I demonstrate that conceptually simple and quantitatively useful models are available to describe both the localized deposition of shock wave energy during dynamic consolidation of a metal powder, and the accompanying effects on the final compact microstructure. The type and extent of transformation may be estimated, as well as the shock conditions and powder characteristics necessary for optimum consolidation. If the shock history is known, such models can be used to describe different microstructural regions in the final compact. I suggest that the marriage of microstructural models to existing hydrodynamic computer programs could provide a means of making realistic predictions of the type, extent and gross distribution of microstructural changes produced when compaction occurs in complex geometries.

Gourdin, W.H.

1984-01-30

396

Computational compact torus experiment  

SciTech Connect

We describe a typical 2D magnetohydrodynamic (MHD) calculation of rundown of plasma in a coaxial, magnetized gun and injection of the plasma and reconnection of the embedded magnetic fields to form a compact toroidal plasma.

Eddleman, J.L.; McNamara, B.; Nash, J.K.; Shearer, J.W.; Turner, W.C.

1980-12-24

397

Compact conformal manifolds  

NASA Astrophysics Data System (ADS)

In this note we begin a systematic study of compact conformal manifolds of SCFTs in four dimensions (our notion of compactness is with respect to the topology induced by the Zamolodchikov metric). Supersymmetry guarantees that such manifolds are Kähler, and so the simplest possible non-trivial compact conformal manifold in this set of geometries is a complex one-dimensional projective space. We show that such a manifold is indeed realized and give a general prescription for constructing complex N-dimensional projective space conformal manifolds as certain small breaking deformations of strongly interacting SCFTs. In many cases, our prescription reduces the construction of such spaces to a study of the chiral ring. We also give an algorithm for constructing more general compact spaces of SCFTs.

Buican, Matthew; Nishinaka, Takahiro

2015-01-01

398

Neutron detectors comprising boron powder  

SciTech Connect

High-efficiency neutron detector substrate assemblies comprising a first conductive substrate, wherein a first side of the substrate is in direct contact with a first layer of a powder material comprising .sup.10boron, .sup.10boron carbide or combinations thereof, and wherein a conductive material is in proximity to the first layer of powder material; and processes of making said neutron detector substrate assemblies.

Wang, Zhehui; Morris, Christopher; Bacon, Jeffrey Darnell; Makela, Mark F; Spaulding, Randy Jay

2013-05-21

399

Luminescence of powdered uranium glasses  

NASA Technical Reports Server (NTRS)

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.

Eubanks, A. G.; Mcgarrity, J. M.; Silverman, J.

1974-01-01

400

Powder collection apparatus/method  

DOEpatents

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.

Anderson, I.E.; Terpstra, R.L.; Moore, J.A.

1994-01-11

401

Powder collection apparatus/method  

DOEpatents

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.

Anderson, Iver E. (Ames, IA); Terpstra, Robert L. (Ames, IA); Moore, Jeffery A. (Ames, IA)

1994-01-11

402

Physical and mechanical metallurgy of high purity Nb for accelerator cavities  

SciTech Connect

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.

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

403

Synthesis, characterization, and microstructural evolution of ultrafine oxide powders  

NASA Astrophysics Data System (ADS)

Phase-pure, homogeneous, single- and multi-component ultrafine ceramic oxide particles (UFPs) were synthesized via flame spray pyrolysis (FSP) of combustible metalloorganic precursors. A variety of single source, atomically mixed, inexpensive, and air stable chemical precursors were used to (1) demonstrate the versatility of FSP to produce high purity UFPs and (2) control their phase and composition. Ultrafine TiOsb2,\\ CeOsb2,\\ 3Alsb2Osb3{*}2SiOsb2 (mullite), and Ysb3Alsb5Osb{12} (YAG) composition powders were produced by injecting a metalloorganic precursor/ethanol solution into a flame. UFP production occurs by combustion of the aerosol droplets of this solution to produce molecular M-O monomers, which then coalesce to form molecular clusters, which in turn form larger particles. These particles then grow via vapor condensation and/or coagulation. The semi-continuous FSP process used 50-100 mL of precursor/min to produce powders at 300-500 g/h. The resulting UFPs were characterized with gas sorption, CHN, TGA, DTA, DRIFTS, XRD, and TEM techniques. Ultrafine TiOsb2 particle sizes were 40-60 nm with surface areas of 35 msp2/g and were mostly unagglomerated, single crystals. Mullite particles were mostly unagglomerated amorphous particles with some interparticle necking. Ultrafine mullite particle sizes ranged from 40-80 nm (due to necking) with surface areas = 45 msp2/g. Ultrafine CeOsb2 particles averaged 80 nm in diameter and were unagglomerated single crystals with surface areas = 10 msp2/g. The compaction and sintering behavior of UFPs were traced with XRD, DRIFTS, and SEM techniques. UFP compacts sinter and densify at lower temperatures than typical of coarser powder compacts. This work reports significant results for which there are no literature precedents. UFP-TiOsb2 densified to 97% of theory with final average grain sizes of $2 mum. CeOsb2 inherent oxygen vacancies render it thermally unstable above 800spcirc$C, where extensive grain growth occurs due to rapid oxygen diffusion. Doping may further inhibit grain growth in all compacts of UFP powders. Future work entails doping in the precursor state as well as solid-state doping.

Baranwal, Rita

404

30 CFR 57.6901 - Black powder.  

Code of Federal Regulations, 2011 CFR

...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...

2011-07-01

405

30 CFR 56.6901 - Black powder.  

Code of Federal Regulations, 2012 CFR

...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...

2012-07-01

406

30 CFR 57.6901 - Black powder.  

Code of Federal Regulations, 2012 CFR

...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...

2012-07-01

407

30 CFR 57.6901 - Black powder.  

Code of Federal Regulations, 2013 CFR

...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...

2013-07-01

408

30 CFR 56.6901 - Black powder.  

Code of Federal Regulations, 2011 CFR

...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...

2011-07-01

409

30 CFR 56.6901 - Black powder.  

Code of Federal Regulations, 2013 CFR

...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...

2013-07-01

410

30 CFR 56.6901 - Black powder.  

...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...

2014-07-01

411

30 CFR 57.6901 - Black powder.  

...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...

2014-07-01

412

30 CFR 57.6901 - Black powder.  

Code of Federal Regulations, 2010 CFR

...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...

2010-07-01

413

30 CFR 56.6901 - Black powder.  

Code of Federal Regulations, 2010 CFR

...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...

2010-07-01

414

Effect of particle-size distribution on the processing properties of atomized iron powder with and without a zinc stearate addition  

Microsoft Academic Search

As a result of an investigation into the effect of particle-size distribution on the processing properties of annealed atomized iron powder (with or without 0.8% zinc stearate), particle-size distribution fields have been found within which the following are ensured:a)a given compactibility and hence a given “green” strength with compacts of the required porosity;b)maximum values of density or strength with compacts

A. F. Zhornyak; V. E. Oliker

1978-01-01

415

Sputter deposited LiPON thin films from powder target as electrolyte for thin film battery applications  

Microsoft Academic Search

Lithium phosphorus oxynitride (LiPON) thin films as solid electrolytes were prepared by reactive radio frequency (rf) magnetron sputtering from Li3PO4 powder compact target. High deposition rates and ease of manufacturing powder target compared with conventional ceramic Li3PO4 targets offer flexibility in handling and reduce the cost associated. Rf power density varied from 1.7Wcm?2 to 3Wcm?2 and N2 flow from 10

C. S. Nimisha; K. Yellareswar Rao; G. Venkatesh; G. Mohan Rao; N. Munichandraiah

2011-01-01

416

Adsorption as a method of doping 3-mol%-yttria-stabilized zirconia powder with copper oxides  

SciTech Connect

The adsorption behavior of Cu[sup 2+] on 3-mol%-yttria-stabilized tetragonal zirconia polycrystalline (3Y-TZP) powder was studied. There is a window of pH values (10 < pH < 11) where adsorption may be used as a method of doping 3Y-TZP with Cu[sup 2+]. The maximum mole percent of the CuO additions is determined by the specific surface area of the 3Y-TZP powder; a powder with a specific surface area of 16.1 m[sup 2]/g is limited to about 1 mol% CuO. Compacts made from powders doped with CuO using this method exhibited an enhancement in superplasticity comparable to that observed in other studies using samples doped with CuO by attrition milling.

Seidensticker, J.R.; Mayo, M.J.; Osseo-Asare, K. (Pennsylvania State Univ., Univ. Park, PA (United States). Dept. of Materials Science and Engineering)

1993-07-01

417

Microstructure of cBN-diamond sintered compact prepared by reaction sintering  

Microsoft Academic Search

cBN-diamond composite sintered compacts (diamond content 15–70 wt %) were prepared by reaction sintering at 7–7.5 GPa and 1400–1700 °C for 10–30 min from the starting powder of the hBN-diamond system in the presence of 1 wt % NH4NO3 as a volatile catalyst. A fully dense sintered compact with 99% conversion from hBN to cBN was obtained at 7 GPa

H. Itoh; H. Takao; H. Iwahara

1991-01-01

418

Mechanical properties of aluminum matrix composites reinforced with sintered ferrous compacts  

Microsoft Academic Search

The current investigation involves fabrication and characterization of squeeze-cast aluminum metal matrix composites reinforced with sintered metal compacts. Four types of metallic powder compacts were used: plain carbon steel, 409 stainless steel, A6 tool steel, and a wear-resistant stainless steel. All the composites were cast under the same nominal conditions, but only the plain carbon steel-reinforced composites contained a significant

Richard P Baron; Coleman Jones; Frank E Wawner; John A Wert

1999-01-01

419

Development of Ti-6Al-4V and Ti-1Al-8V-5Fe Alloys Using Low-Cost TiH2 Powder Feedstock  

NASA Astrophysics Data System (ADS)

Thermo-mechanical processing was performed on two titanium alloy billets, a beta-titanium alloy (Ti1Al8V5Fe) and an alpha-beta titanium alloy (Ti6Al4V), which had been produced using a novel low-cost powder metallurgy process that relies on the use of TiH2 powder as a feedstock material. The thermomechanical processing was performed in the beta region of the respective alloys to form 16-mm diameter bars. The hot working followed by the heat treatment processes not only eliminated the porosity within the materials but also developed the preferred microstructures. Tensile testing and rotating beam fatigue tests were conducted on the as-rolled and heat-treated materials to evaluate their mechanical properties. The mechanical properties of these alloys matched well with those produced by the conventional ingot processing route.

Joshi, Vineet V.; Lavender, Curt; Moxon, Vladimir; Duz, Vlad; Nyberg, Eric; Weil, K. Scott

2013-04-01

420

Explosively generated shock wave processing of metal powders by instrumented detonics  

NASA Astrophysics Data System (ADS)

The highest pressures generated by dynamic processes resulting either from high velocity impact or by spontaneous release of high energy rate substances in direct contact with a metal find superior applications over normal mechanical means. The special feature of explosive loading to the powder materials over traditional methods is its controlled detonation pressure which directly transmits shock energy to the materials which remain entrapped inside powder resulting into several micro-structural changes and hence improved mechanical properties. superalloy powders have been compacted nearer to the theoretical density by shock wave consolidation. In a single experimental set-up, compaction of metal powder and measurement of detonation velocity have been achieved successfully by using instrumented detonics. The thrust on the work is to obtain uniform, crack-free and fracture-less compacts of superalloys having intact crystalline structure as has been examined from FE-SEM, XRD and mechanical studies. Shock wave processing is an emerging technique and receiving much attention of the materials scientists and engineers owing to its excellent advantages over traditional metallurgical methods due to short processing time, scaleup advantage and controlled detonation pressure.

Sharma, A. D.; Sharma, A. K.; Thakur, N.

2013-06-01

421

Atom probe study on the bulk nanocomposite SmCo/Fe permanent magnet produced by ball-milling and warm compaction  

E-print Network

- structure and composition distributions in the high performance nanocomposite SmCo/Fe permanent magnet compaction of hard magnetic and soft magnetic powders. The raw powder materials, commercial SmCo5 and aAtom probe study on the bulk nanocomposite SmCo/Fe permanent magnet produced by ball

Liu, J. Ping

422

Compact groups of galaxies  

E-print Network

Compact groups of galaxies have posed a number of challenging questions. Intensive observational and theoretical studies are now providing answers to many of these, and at the same time, are revealing unexpected new clues about the nature and role of these systems. Most compact groups contain a high fraction of galaxies having morphological or kinematical peculiarities, nuclear radio and infrared emission, and starburst or active galactic nuclei (AGN) activity. They contain large quantities of diffuse gas and are dynamically dominated by dark matter. They most likely form as subsystems within looser associations and evolve by gravitational processes. Strong galaxy interactions result and merging is expected to lead to the ultimate demise of the group. Compact groups are surprisingly numerous, and may play a significant role in galaxy evolution.

Paul Hickson

1997-10-25

423

Bonding of a silver sheath on textured-powder ribbons of green-state Bi-2212 superconductor  

NASA Astrophysics Data System (ADS)

A novel method is being developed for fabrication of textured-powder jelly-roll (TPJR) Bi-2212/Ag superconducting wire for applications in high-field magnets. In this process two silver foils must be fused together to enclose a ribbon of compacted, textured Bi-2212 fine powder. Fusing the silver foils must be accomplished with minimum heating of the superconducting powder filling. We are investigating methods using cold-welding, ultrasonic welding, and laser welding. Results of those investigations will be reported.

Smit, Klaus; McIntyre, Peter; Damborsky, Kyle; Lu, Feng; Pogue, Nathaniel

2011-10-01

424

Phosphorus as sintering activator in powder metallurgical steels: characterization of the distribution and its technological impact.  

PubMed

Powder metallurgy is a highly developed method of manufacturing reliable ferrous parts. The main processing steps in a powder metallurgical line are pressing and sintering. Sintering can be strongly enhanced by the formation of a liquid phase during the sintering process when using phosphorus as sintering activator. In this work the distribution (effect) of phosphorus was investigated by means of secondary ion mass spectrometry (SIMS) supported by Auger electron spectroscopy (AES) and electron probe micro analysis (EPMA). To verify the influence of the process conditions (phosphorus content, sintering atmosphere, time) on the mechanical properties, additional measurements of the microstructure (pore shape) and of impact energy were performed. Analysis of fracture surfaces was performed by means of scanning electron microscopy (SEM). The concentration of phosphorus differs in the samples from 0 to 1% (w/ w). Samples with higher phosphorus concentrations (1% (w/ w) and above) are also measurable by EPMA, whereas the distributions of P at technically relevant concentrations and the distribution of possible impurities are only detectable (visible) by means of SIMS. The influence of the sintering time on the phosphorus distribution will be demonstrated. In addition the grain boundary segregation of P was measured by AES at the surface of in-situ broken samples. It will be shown that the distribution of phosphorus depends also on the concentration of carbon in the samples. PMID:15098083

Krecar, Dragan; Vassileva, Vassilka; Danninger, Herbert; Hutter, Herbert

2004-06-01

425

Mechanical behaviour of pressed and sintered titanium alloys obtained from master alloy addition powders.  

PubMed

The fabrication of the workhorse Ti-6Al-4V alloy and of the Ti-3Al-2.5V alloy was studied considering the master alloy addition variant of the blending elemental approach conventionally used for titanium powder metallurgy. The powders were characterised by means thermal analysis and X-ray diffraction and shaped by means of uniaxial pressing. The microstructural evolution with the sintering temperature (900-1400 °C) was evaluated by SEM and EDS was used to study the composition. XRD patterns as well as the density by Archimedes method were also obtained. The results indicate that master alloy addition is a suitable way to fabricate well developed titanium alloy but also to produce alloy with the desired composition, not available commercially. Density of 4.3 g/cm³ can be obtained where a temperature higher than 1200 °C is needed for the complete diffusion of the alloying elements. Flexural properties comparable to those specified for wrought Ti-6Al-4V medical devices are, generally, obtained. PMID:23026730

Bolzoni, L; Esteban, P G; Ruiz-Navas, E M; Gordo, E

2012-11-01

426

Process design applied to optimise a directly compressible powder produced via a continuous manufacturing process.  

PubMed

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

Gonnissen, Y; Gonçalves, S I V; De Geest, B G; Remon, J P; Vervaet, C

2008-03-01

427

Microstructure of ball milled and compacted Co-Ni-Al alloys from range Journal: Journal of Microscopy  

E-print Network

of Metallurgy and Materials Science Dutkiewicz, Jan; Polish Academy of Sciences, Institute of Metallurgy and Materials Science Rogal, £ukasz; Polish Academy of Sciences, Institute of Metallurgy and Materials Science Grzonka, Justyna; Polish Academy of Sciences, Institute of Metallurgy and Materials Science Cesari, Eduard

428

Studies of electroless nickel under bump metallurgy—Solder interfacial reactions and their effects on flip chip solder joint reliability  

Microsoft Academic Search

The electroless-deposited Ni-P under bump metallurgy (UBM) layer was fabricated on Al pads for Sn containing solder bumps.\\u000a The amount of P in the electroless Ni film was optimized by controlling complexing agents and the pH of plating solution.\\u000a The interfacial reaction at the electroless Ni UBM\\/solder interface was investigated in this study. The intermetallic compound\\u000a (IMC) formed at the

Young-Doo Jeon; Kyung-Wook Paik; Kyung-Soon Bok; Woo-Suk Choi; Chul-Lae Cho

2002-01-01

429

Automated dry powder dispenser for explosive components  

SciTech Connect

Sandia and Mound are developing a workcell that will automate the assembly of explosive components. Sandia is responsible for the automated powder dispenser subsystem. Automated dispensing of explosive powders in the past resulted in separation or segregation of powder constituents. The Automated Dry Powder Dispenser designed by Sandia achieves weight tolerances of {plus_minus}0.1 mg while keeping powderoxidizer separation to a minimum. A software control algorithm compensates fore changes in powder flow due to lot variations, temperature, humidity, and the amount of powder left in the system.

Garcia, P. [Sandia National Labs., Albuquerque, NM (United States); Salmonson, J.C. [EG and G Idaho, Inc., Idaho Falls, ID (United States)

1992-09-01

430

Automated dry powder dispenser for explosive components  

SciTech Connect

Sandia and Mound are developing a workcell that will automate the assembly of explosive components. Sandia is responsible for the automated powder dispenser subsystem. Automated dispensing of explosive powders in the past resulted in separation or segregation of powder constituents. The Automated Dry Powder Dispenser designed by Sandia achieves weight tolerances of {plus minus}0.1 mg while keeping powderoxidizer separation to a minimum. A software control algorithm compensates fore changes in powder flow due to lot variations, temperature, humidity, and the amount of powder left in the system.

Garcia, P. (Sandia National Labs., Albuquerque, NM (United States)); Salmonson, J.C. (EG and G Idaho, Inc., Idaho Falls, ID (United States))

1992-01-01

431

Industrial Optimization Compact Course  

E-print Network

Industrial Optimization Compact Course and Challenge Workshop Optimization plays a crucial role in designing and conducting industrial processes. The potential gains range from saving valuable resources over makers from industry and academia to initiate new projects and to foster new structured collaborations

Kirches, Christian

432

Highly compact composite antenna  

Microsoft Academic Search

The highly compact antenna proposed in this communication consists of a judicious association of equivalent magnetic current source with equivalent electric current source. This composite antenna presents a directivity radiation pattern analogous to one of the microstrip ceramic antennas but can be used at low frequencies. The antenna measurements confirm the promising performances obtained from electromagnetic simulations.

M. Pigeon; C. Morlaas; H. Aubert; B. Souny

2009-01-01

433

Local Microcode Compaction Techniques  

Microsoft Academic Search

Microcode compaction is an essential tool for the compilation of high-level language microprograms into microinstructions with parallel microoperations. Although guaranteeing minimum execution time is an exponentially complex problem, recent research indicates that it is not difficult to obtain practical results. This paper, which assumes no prior knowledge of microprogramming on the part of the reader, surveys the approaches that have

David Landskov; Scott Davidson; Bruce Shriver; Patrick W. Mallett

1980-01-01

434

Local microcode compaction techniques  

E-print Network

Microcode compaction is an essential tool for the compilation of high-level language microprograms into microinstructions with parallel microoperations. Although guaranteeing minimum execution time is an exponentially complex problem, recent research indicates that it is not difficult to obtain practical results. This paper, which

David Landskov; Scott Davidson; Bruce Shriver; Patrick W. Mallett

1980-01-01

435

Structure and properties of niobium powder produced by hydrogen treatment from niobium swarf  

SciTech Connect

Results are presented from an investigation into the reaction of hydrogen with niobium and of the structure and properties of powder produced from swarf using a hydridation-disintegration-dehydridation method. The kinetics of hydrogen gas absorption by niobium of various degrees of compactness were assessed along with hydrogen evolution from niobium hydrides. The structures and properties were evaluated by electron microprobe analysis, optical and electron microscopy, weight measurement, hardness testing, and x-ray diffraction. Particle sizes were determined by sieve analysis. Uses for the resulting powders in machines and as superconductors are addressed.

Kobzenko, G.F.; Kobzenko, N.S.; Flis, A.A.; Valentinov, V.D.

1988-03-01

436

Pinwheel patterns and powder diffraction  

Microsoft Academic Search

Pinwheel patterns and their higher dimensional generalisations display continuous circular or spherical symmetries in spite of being perfectly ordered. The same symmetries show up in the corresponding diffraction images. Interestingly, they also arise from amorphous systems, and also from regular crystals when investigated by powder diffraction. We present first steps and results towards a general frame to investigate such systems,

Michael Baake; D. Frettlöh; Uwe Grimm

2007-01-01

437

High resolution powder blast micromachining  

Microsoft Academic Search

Powder blasting, or Abrasive Jet Machining (AJM), is a technique in which a particle jet is directed towards a target for mechanical material removal. It is a fast, cheap and accurate directional etch technique for brittle materials like glass, silicon and ceramics. By introducing electroplated copper as a new mask material, the feature size of this process was decreased. It

Henk Wensink; J. W. Berenschot; Henri V. Jansen; Miko C. Elwenspoek

2000-01-01

438

"Powdered Magnesium: Carbon Dioxide Combustion for Mars Propulsion"  

NASA Technical Reports Server (NTRS)

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.

Foote, John P.; Litchford, Ron J.

2005-01-01

439

Behaviour of colloidal silicas during uniaxial compaction Franoise Ehrburger and Jacques Lahaye  

E-print Network

1349 Behaviour of colloidal silicas during uniaxial compaction Françoise Ehrburger and Jacques > 2). Abstract. 2014 The pressure P transmitted by colloidal silica samples during low speed a percolation law E '" ( f - f,)'. The percolation threshold te obtained for silver powder beams [1] is 0

Paris-Sud XI, Université de

440

The internal form of compacted ceramic components: a comparison of a finite element modelling with experiment  

Microsoft Academic Search

This paper is concerned with the internal form of compacted ceramic green components. The structural inhomogeneity of alumina specimens, compressed in a top pressed cylindrical die, is studied experimentally, by using lead balls as tracers to detect the densification, as well as by numerical computation. The flow behaviour of a ceramic powder, an agglomerated alumina, is described by the modified

?smail Aydin; Brian J. Briscoe; Kenan Y. ?anlitürk

1996-01-01

441

Constitutive relations to predict plastic deformations of porous metals in compaction  

Microsoft Academic Search

Several yield criteria for sintered powder metals were compared to each other. The most reasonable one was selected and modified to derive constitutive relations for a description of the plastic deformation in compaction. The yield criterion uses three coefficients. It was found that two of them are dependent on each other and can be represented as functions of the plastic

Jong Jin Park

1995-01-01

442

Advanced composites take a powder  

SciTech Connect

To a professional chemist with more than 25 years of industrial experience, the world of advanced composites is a fascinating new venue. Here resins and fibers come together in a completely synergistic partnership, achieving marvels of strength and light weight that make advanced composite materials virtually the only solution for challenging applications. In the late 1980s, Professor John Muzzy of the Georgia Institute of Technology, was intrigued by the physical properties of thermoplastics, and he developed a new way to bring the thermoplastic resins together with high-performance fibers. As part of the work Muzzy did with Lockheed and NASA he demonstrated that electrostatic powder coating was an attractive new method for combining thermoplastic resins with reinforcing fibers. Presentation of this work by Lockheed at a government-industry conference led to a new project for Muzzy, sponsored by NASA Langley. Powder prepregging proved to be the attractive alternative that NASA was looking for. While working on powder prepregging with LaRC-TPI, Muzzy and his colleagues developed methods for exposing all of the fibers to the powder to improve the distribution of the resin on the tow, a continuous bundle of filaments. Optimal resin distribution was achieved by spreading the moving tow. A very flexible towpreg was produced by maintaining the spread tow through the powder coating chamber and into the oven, where the resin particles were fused to the individual filaments. Muzzy's invention has enabled Custom Composite Materials, Inc. to offer resin/fiber combinations based on thermoplastic resins such as nylon and polypropylene. Beyond the expected advantages over epoxy thermoset systems, they are beginning to exploit a fundamental property of thermoplastic resins: viscoelasticity, which can be defined as the resistance to flow as a function of applied stress. Thermoplastics have a much higher viscoelasticity than thermosets.

Holty, D.W. (Custom Composite Materials, Inc., Atlanta, GA (United States))

1993-06-01

443

Near-Net Shape Fabrication Using Low-Cost Titanium Alloy Powders  

SciTech Connect

The use of titanium in commercial aircraft production has risen steadily over the last half century. The aerospace industry currently accounts for 58% of the domestic titanium market. The Kroll process, which has been used for over 50 years to produce titanium metal from its mineral form, consumes large quantities of energy. And, methods used to convert the titanium sponge output of the Kroll process into useful mill products also require significant energy resources. These traditional approaches result in product forms that are very expensive, have long lead times of up to a year or more, and require costly operations to fabricate finished parts. Given the increasing role of titanium in commercial aircraft, new titanium technologies are needed to create a more sustainable manufacturing strategy that consumes less energy, requires less material, and significantly reduces material and fabrication costs. A number of emerging processes are under development which could lead to a breakthrough in extraction technology. Several of these processes produce titanium alloy powder as a product. The availability of low-cost titanium powders may in turn enable a more efficient approach to the manufacture of titanium components using powder metallurgical processing. The objective of this project was to define energy-efficient strategies for manufacturing large-scale titanium structures using these low-cost powders as the starting material. Strategies include approaches to powder consolidation to achieve fully dense mill products, and joining technologies such as friction and laser welding to combine those mill products into near net shape (NNS) preforms for machining. The near net shape approach reduces material and machining requirements providing for improved affordability of titanium structures. Energy and cost modeling was used to define those approaches that offer the largest energy savings together with the economic benefits needed to drive implementation. Technical feasibility studies were performed to identify the most viable approaches to NNS preform fabrication using basic powder metallurgy mill product forms as the building blocks and advanced joining techniques including fusion and solid state joining to assemble these building blocks into efficient machining performs.

Dr. David M. Bowden; Dr. William H. Peter

2012-03-31

444

Explosive Compations of Intermetallic-Forming Powder Mixtures for Fabricating Structural Energetic Materials  

NASA Astrophysics Data System (ADS)

A double-tube implosion geometry is used to explosively shock consolidate intermetallic-forming Ni-Al, Ta-Al, Nb-Al, Mo-Al and W-Al powder mixtures for fabricating bulk structural energetic materials, with mechanical strength and ability to undergo impact-initiated exothermic reactions. The compacts are characterized based on uniformity of micro structure and degree of densification. Mechanical properties of the compacts are characterized over the strain-rate range of 10-3 to 104 s-1. The impact reactivity is determined using rod-on-anvil experiments, in which disk-shaped compacts mounted on a copper projectile, are impacted against a steel anvil in using a 7.62 mm gas gun. The impact reactivity of the various explosively-consolidated reactive powder mixture compacts is correlated with overall kinetic energy and impact stress to determine their influence on threshold for reaction initiation. The characteristics of the various compacts, their mechanical properties and impact-initiated chemical reactivity will be described in this paper.

Du, S. W.; Aydelotte, B.; Fondse, D.; Wei, C.-T.; Jiang, F.; Herbold, E.; Vecchio, K.; Meyers, M. A.; Thadhani, N. N.

2009-12-01

445

State-of-the-art of recycling e-wastes by vacuum metallurgy separation.  

PubMed

In recent era, more and more electric and electronic equipment wastes (e-wastes) are generated that contain both toxic and valuable materials in them. Most studies focus on the extraction of valuable metals like Au, Ag from e-wastes. However, the recycling of metals such as Pb, Cd, Zn, and organics has not attracted enough attentions. Vacuum metallurgy separation (VMS) processes can reduce pollution significantly using vacuum technique. It can effectively recycle heavy metals and organics from e-wastes in an environmentally friendly way, which is beneficial for both preventing the heavy metal contaminations and the sustainable development of resources. VMS can be classified into several methods, such as vacuum evaporation, vacuum carbon reduction and vacuum pyrolysis. This paper respectively reviews the state-of-art of these methods applied to recycling heavy metals and organics from several kinds of e-wastes. The method principle, equipment used, separating process, optimized operating parameters and recycling mechanism of each case are illustrated in details. The perspectives on the further development of e-wastes recycling by VMS are also presented. PMID:25407107

Zhan, Lu; Xu, Zhenming

2014-12-16

446

Bridging the gap between metallurgy and fatigue reliability of hydraulic turbine runners  

NASA Astrophysics Data System (ADS)

The failure of hydraulic turbine runners is a very rare event. Hence, in order to assess the reliability of these components, one cannot rely on statistical models based on the number of failures in a given population. However, as there is a limited number of degradation mechanisms involved, it is possible to use physically-based reliability models. Such models are more complicated but have the advantage of being able to account for physical parameters in the prediction of the evolution of runner degradation. They can therefore propose solutions to help improve reliability. With the use of such models, the effect of materials properties on runner reliability can easily be illustrated. This paper will present a brief review of the Kitagawa-Takahashi diagram that links the damage tolerance approach, based on fracture mechanics, to the stress or strain-life approaches. This diagram is at the centre of the reliability model used in this study. Using simplified response spectra obtained from on-site runner stress measurements, the paper will show how fatigue reliability is impacted by materials fatigue properties, namely fatigue crack propagation behaviour and fatigue limit obtained on S-N curves. It will also present a review of the most important microstructural features of 13%Cr- 4%Ni stainless steels used for runner manufacturing and will review how they influence fatigue properties in an effort to bridge the gap between metallurgy and turbine runners reliability.

Thibault, D.; Gagnon, M.; Godin, S.

2014-12-01

447

Emissions from pre-Hispanic metallurgy in the South American atmosphere.  

PubMed

Metallurgical activities have been undertaken in northern South America (NSA) for millennia. However, it is still unknown how far atmospheric emissions from these activities have been transported. Since the timing of metallurgical activities is currently estimated from scarce archaeological discoveries, the availability of reliable and continuous records to refine the timing of past metal deposition in South America is essential, as it provides an alternative to discontinuous archives, as well as evidence for global trace metal transport. We show in a peat record from Tierra del Fuego that anthropogenic metals likely have been emitted into the atmosphere and transported from NSA to southern South America (SSA) over the last 4200 yrs. These findings are supported by modern time back-trajectories from NSA to SSA. We further show that apparent anthropogenic Cu and Sb emissions predate any archaeological evidence for metallurgical activities. Lead and Sn were also emitted into the atmosphere as by-products of Inca and Spanish metallurgy, whereas local coal-gold rushes and the industrial revolution contributed to local contamination. We suggest that the onset of pre-Hispanic metallurgical activities is earlier than previously reported from archaeological records and that atmospheric emissions of metals were transported from NSA to SSA. PMID:25353346

De Vleeschouwer, François; Vanneste, Heleen; Mauquoy, Dmitri; Piotrowska, Natalia; Torrejón, Fernando; Roland, Thomas; Stein, Ariel; Le Roux, Gaël

2014-01-01

448

Tribological behavior of liquid metallurgy-processed AA 6061-B4C composites  

NASA Astrophysics Data System (ADS)

Aluminum metal matrix composites (AMMCs) possess improved properties compared to their monolithic counterparts and serve as a reliable alternative to replace them for applications that are considered as their niche. In the present investigation, 6061 Al alloy-10 wt% B4C composite is fabricated through liquid metallurgy stir casting technique and analyzed for its tribological characteristics. The uniform distribution of B4C reinforcement particles in the composite is achieved by the above route and is characterized using microstructure analysis and x-ray diffraction spectrum. The dry wear tests have been conducted under ambient conditions using a pin-on-disc tribometer. The worn surface and debris of the composite are also characterized using a scanning electron microscope (SEM) and energy-dispersive x-ray spectroscopy (EDS). It is found that the combination of adhesion, delamination and abrasion constitute the predominant wear mechanism and this is influenced by the B4C particles, applied load, sliding distance and speed. The wear and friction coefficient increase with increase in applied load for all the load conditions studied. While the sliding speed fosters the engendering of a mechanically mixed layer (MML) to reduce the wear and friction coefficient, in contrast, the increase in sliding distance scuttles the MML formation owing to abrasion induced by the hard B4C particles.

Monikandan, V. V.; Joseph, M. A.; Rajendrakumar, P. K.; Sreejith, M.

2015-01-01

449

Artificial neural network modeling of the drilling process of self-lubricated aluminum\\/alumina\\/graphite hybrid composites synthesized by powder metallurgy technique  

Microsoft Academic Search

In recent years, the consumption of metal matrix composites (MMCs) materials in many engineering fields has increased enormously. Most industries are usually looking for replacement of ferrous components with lighter and high strength alloys like Al metal matrix composites. Despite the superior mechanical and thermal properties of particulate metal matrix composites (PMMCs), their poor machinability is the main drawback to

Mohammed T. Hayajneh; Adel Mahmood Hassan; Ahmad Turki Mayyas

2009-01-01

450

Reservoir compaction and land subsidence  

Microsoft Academic Search

Subsurface hydrocarbon removal induces a reservoir compaction that migrates to the ground surface and causes the land to subside. While compaction depends primarily on the fluid pore pressure drawdown, the thickness and the mechanical compressibility of the depleted formation, the amount of compaction reaching the surface depends on the depth and size of the producing field and the stiffness of

Giuseppe Gambolati; Massimiliano Ferronato; Pietro Teatini

2006-01-01

451

COMPACT EXCHANGERS FOR PHASE CHANGE  

Microsoft Academic Search

Compact heat exchangers are being increasingly considered for duties involving phase change processes of boiling and condensation. In many cases such applications are completely new and no previous experience or information on exchanger performance is available. Understanding the thermal-hydraulic characteristics of flow passages of compact heat exchangers for phase change duties is therefore vitally important. Even for those compact heat

Vishwas V. Wadekar

452

Review: aqueous tape casting of ceramic powders  

Microsoft Academic Search

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

D. Hotza; P. Greil

1995-01-01

453

Processing and characterization of carob powder  

Microsoft Academic Search

The possibility of processing roasted carob powder using different time–temperature combinations has been studied. The physical and chemical characteristics of the prepared carob powders were also examined. The most acceptable roasted carob powder was obtained by roasting kibbled carob at 150°C for 60 min. The roasted carob powder contained 9.00, 5.82, 2.84 and 0.74% moisture, protein, ash and fat, respectively.

Ali K. Yousif; H. M. Alghzawi

2000-01-01

454

Shock compaction of a porous pyrotechnic material  

SciTech Connect

The results of an experimental program to generate Hugoniot data for an unreacted pyrotechnic material are discussed and the data presented. The program included both sample fabrication and experimental determination of stress-particle velocity Hugoniot data for the pyrotechnic, titanium hydride-potassium perchlorate (TiH/sub 2/-KClO/sub 4/), at two densities. The TiH/sub 2/-KClO/sub 4/, which was supplied as a powder mixture, was pressed to the desired bulk sample density and size using a ram and die technique. Samples were produced with nominal 2.02 or 2.27 g/cm/sup 3/ densities. Hugoniot data were generated on the porous pyrotechnic samples using standard flat plate impact techniques. The experimental program provided information defining the shock compaction behavior of porous TiH/sub 2/-KClO/sub 4/ up to 70 kbar. The Hugoniot data for both sample densities indicated full compaction was achieved in the 15 to 20 kbar stress range.

Lee, L. M.; Schwarz, A. C.

1980-01-01

455

Synthesis and characterization of calcia partially stabilized zirconia-hydroxyapatite powders prepared by co-precipitation method  

Microsoft Academic Search

It was recently been reported that calcia partially stabilized zirconia can be used as a reinforcement phase in zirconia-hydroxyapatite composites. Composites prepared by a precipitation method lead to the formation of homogeneous powders, easily compacted without addition of other phases. In this work, hydroxyapatite-zirconia composites were prepared by a similar precipitation route previously used. Here, it was lightly modified in

Viviane Viana Silva; Fernando Soares Lameiras; Rosana Zacarias Domingues

2001-01-01

456

Compact dc link  

Microsoft Academic Search

The EPRI Compact Substation Project (a HVDC Converter Station) was developed, designed, and constructed per EPRI Agreement RP213. In December 1983, the converter station operated at its rating (100 MW power transmission and 300 kV dc bias plus 100 kV operating voltage). From January to May 1984, the converter station operated at various power transmission levels. Operation was intermittent due

Flairty

1991-01-01

457

Assessment of Thermal Transitions by Dynamic Mechanical Analysis (DMA) Using a Novel Disposable Powder Holder  

PubMed Central

Foods and pharmaceuticals materials are exposed to various environmental conditions during processing and while in storage; therefore, stability and quality are key attributes of concern. The properties of foods and pharmaceutical materials that define their quality are affected by conditions such as temperature, humidity and time. Glass transition is considered a key material property to understand how these external conditions affect the stability and quality of foods and pharmaceuticals. Thus, investigating the thermo-mechanical properties of these materials as well as characterizing the glass transition temperature have a great interest not only in the food industry, but also extend to the pharmaceutical and polymer industries. The aim of this study was to design and test a new disposable powder holder that allows the use of a dynamic mechanical analysis (DMA) instrument to test and characterize loose powder samples. The disposable aluminum powder holder was designed and constructed to be used in the single cantilever configuration on a TA Instruments RSA III DMA. Three different powder samples – Felodipine, polyethylene-oxide (MW 900 kDa) and HPMC (E4M) – were used for validation. The use of this powder holder allows the detection of different thermal changes of powder samples without compacting and when large sample size is necessary for detection and/or interpretation.

Abiad, Mohamad G.; Campanella, Osvaldo H.; Carvajal, M. Teresa

2010-01-01

458

Novel approach for the bulk synthesis of nanocrystalline yttria doped thoria powders via polymeric precursor routes  

NASA Astrophysics Data System (ADS)

Three different polymeric precursor routes viz., (i) amorphous citrate process, (ii) Pechini process and (iii) polyethylene glycol assisted process were compared for synthesising nanocrystalline powders of 7.5 mol% yttria doped thoria (YDT). In each of the processes, parameters such as metal-to-fuel ratio or composition of fuel were varied and the effects were analysed. TG/DTA studies were conducted to identify the ignition temperatures of the precursors. Also, a novel experimental procedure with controlled combustion was devised for the preparation of powders based on the thermal analysis data. All the processes result in phase pure and nanocrystalline powders. The average crystallite size of the powders ranged between 9 and 18 nm. The powder samples were analysed for their carbon content and studied for their sinterability. Densities as high as 99% th.d. could be achieved by sintering the compacts of powders obtained from (i) amorphous citrate process with CA/M ratios 2.0 and 3.0, (ii) Pechini processes (independent of fuel composition) and (iii) PEG-assisted process using PEG 4000 at a relatively low temperature of 1500 °C for 2 h.

Ganesan, Rajesh; Vivekanandhan, S.; Gnanasekaran, T.; Periaswami, G.; Srinivasa, Raman S.

2004-02-01

459

Powder Diffraction in Zeolite Science  

NASA Astrophysics Data System (ADS)

This tutorial discusses the fundamental principles of X-ray diffraction and its applications in zeolite science. The early sections review the physics of diffraction, crystal symmetry, and reciprocal space. We discuss how the intensity of diffracted radiation is affected both by geometric effects involving detection (the Lorentz-polarization factor) and by the arrangement of atoms within the crystal (the structure factor). The differences between powder diffraction and single-crystal diffraction are then described, and differences between X-ray and neutron diffraction are also discussed. Later sections describe the effects of symmetry, lattice substitution, crystallite size, residual strain, preferred orientation, and X-ray absorption. Special emphasis is placed on the proper application of the Scherrer analysis in reporting crystalize size. The principles of structure solution from direct methods and Patterson methods are then introduced, and a description of Rietveld analysis is given. Finally the effects of stacking disorder on a powder diffraction pattern are presented.

Burton, Allen W.

460

Pinwheel patterns and powder diffraction  

E-print Network

Pinwheel patterns and their higher dimensional generalisations display continuous circular or spherical symmetries in spite of being perfectly ordered. The same symmetries show up in the corresponding diffraction images. Interestingly, they also arise from amorphous systems, and also from regular crystals when investigated by powder diffraction. We present first steps and results towards a general frame to investigate such systems, with emphasis on statistical properties that are helpful to understand and compare the diffraction images. We concentrate on properties that are accessible via an alternative substitution rule for the pinwheel tiling, based on two different prototiles. Due to striking similarities, we compare our results with the toy model for the powder diffraction of the square lattice.

Michael Baake; Dirk Frettlöh; Uwe Grimm

2006-10-06

461

Amorphous rare earth magnet powders  

SciTech Connect

Gas atomization (GA) processing does not generally have a high enough cooling rate to produce the initial amorphous microstructure needed to obtain optimal magnetic properties in RE{sub 2}Fe{sub 14}B alloys. Phase separation and an underquenched microstructure result from detrimental {alpha}-Fe precipitation, and the resulting magnetic domain structure is very coarse. Additionally, there is a dramatic dependence of the magnetic properties on the cooling rate (and therefore the particle size) and the powders can be sensitive to environmental degradation. Alloy compositions designed just for GA (as opposed to melt spinning) are necessary to produce an amorphous structure that can be crystallized to result in a fine structure with magnetic properties which are independent of particle size. The addition of titanium and carbon to the melt has been found to change the solidification process sufficiently to result in an ``overquenched`` state in which most of the powder size fractions have an amorphous component. Crystallization with a brief heat treatment produces a structure which has improved magnetic properties, in part due to the ability to use compositions with higher Fe contents without {alpha}-Fe precipitation. Results from magnetometry, magnetic force microscopy, and x-ray analyses will be used to contrast the microstructure, domain structure, and magnetic properties of this new generation of amorphous powders with their multiphase predecessors.

Sellers, C.H.; Branagan, D.J.; Hyde, T.A. [Idaho National Engineering Lab., Idaho Falls, ID (United States); Lewis, L.H. [Brookhaven National Lab., Upton, NY (United States). Dept. of Applied Science; Panchanathan, V. [Magnequench International, Anderson, IN (United States)

1996-08-01

462

Anti-Corrosive Powder Particles  

NASA Technical Reports Server (NTRS)

The National Aeronautics and Space Administration (NASA) seeks partners for a new approach in protecting embedded steel surfaces from corrosion. Corrosion of reinforced steel in concrete structures is a significant problem for NASA structures at Kennedy Space Center (KSC) because of the close proximity of the structures to salt spray from the nearby Atlantic Ocean. In an effort to minimize the damage to such structures, coatings were developed that could be applied as liquids to the external surfaces of a substrate in which the metal structures were embedded. The Metallic Pigment Powder Particle technology was developed by NASA at KSC. This technology combines the metallic materials into a uniform particle. The resultant powder can be sprayed simultaneously with a liquid binder onto the surface of concrete structures with a uniform distribution of the metallic pigment for optimum cathodic protection of the underlying steel in the concrete. Metallic Pigment Powder Particle technology improves upon the performance of an earlier NASA technology Liquid Galvanic Coating (U.S. Patent No. 6,627,065).

Parker, Donald; MacDowell, Louis, III

2005-01-01

463

Numerical Simulation of Cold Pressing of Armstrong CP-Ti Powders  

SciTech Connect

Numerical simulation results for the cold pressing of Armstrong CP-Ti Powders are presented. The computational model was implemented in the commercial finite element program ABAQUSTM. Several simulation cases were conducted for cylindrical samples with different friction coefficients and different compaction pressures, under both single-action and dual-action uniaxial pressing. Numerical simulation results for the density distribution are compared against experimental data in order to validate the computational model.

Sabau, Adrian S [ORNL] [ORNL; Gorti, Sarma B [ORNL] [ORNL; Peter, William H [ORNL] [ORNL; Chen, Wei [ORNL] [ORNL; Yamamoto, Yukinori [ORNL] [ORNL

2012-01-01

464

Sintering densification and microstructural evolution of injection molding grade 17-4 PH stainless steel powder  

Microsoft Academic Search

Densification behavior is investigated by means of dilatometry for powder-injection-molded (PIM) and die-compacted 17-4 PH\\u000a stainless steel during sintering in pure H2 and H2 + N2. The corresponding microstructural evolution is examined by quenching in a vertical furnace at various stages of sintering.\\u000a The results show that in comparison with pure H2, the H2 + N2 atmosphere retards densification and

Yunxin Wu; Debby Blaine; Connie Schlaefer; Brian Marx; Randall M. German

2002-01-01

465

Investigation of the microstructure of milk protein concentrate powders during rehydration: alterations during storage.  

PubMed

The aim of this work was to use scanning electron microscopy to investigate the microstructure of rehydrated milk protein concentrate powder (MPC) particles. A sample preparation method for scanning electron microscopy analysis of rehydrated MPC particles is described and used to characterize the time course of dissolution and the effects of prior storage on the dissolution process. The results show that a combination of different types of interactions (e.g., bridges, direct contact) between casein micelles results in a porous, gel-like structure that restrains the dispersion of individual micelles into the surrounding liquid phase without preventing water penetration and solubilization of nonmicellar components. During storage of the powder, increased interactions occur between and within micelles, leading to compaction of micelles and the formation of a monolayer skin of casein micelles packed close together, the combination of which are proposed to be responsible for the slow dissolution of stored MPC powders. PMID:20105518

Mimouni, A; Deeth, H C; Whittaker, A K; Gidley, M J; Bhandari, B R

2010-02-01

466

The investigation of die-pressing and sintering behavior of ITP CP-Ti and Ti-6Al-4V powders  

SciTech Connect

This paper investigated the die-pressing and sintering behavior of the low-cost CP-Ti and Ti-6Al- 4V powders made by the Armstrong Process . The Armstrong powders have an irregular coral like, dendritic morphology, with a dendrite size of approximately 2-5 m. As-received as well as milled powders were uniaxially pressed at designated pressures up to 690 MPa to form disk samples with different aspect ratios. In the studied pressure range, an empirical powder compaction equation was applied to linearize the green density pressure relationship, and powder compaction parameters were obtained. The Armstrong Ti-64 powder exhibited a significantly higher sinterability than the CP-Ti powder. This was explained to be due to the higher diffusivity of V at the sintering temperature. The Ti-64 samples with a green density of 71.0% increased to 99.6% after sintering at 1300oC for 1 hour. An ex-situ technique was used to track the powder morphology change before and after sintering.

Chen, Wei [ORNL; Yamamoto, Yukinori [ORNL; Peter, William H [ORNL; Clark, Michael B [ORNL; Nunn, Stephen D [ORNL; Kiggans, Jim [ORNL; Muth, Thomas R [ORNL; Blue, Craig A [ORNL; Williams, James C [Ohio State University; Fuller, Brian [International Titanium Powder; Akhtar, Kamal [International Titanium Powder

2012-01-01

467

Method for Detecting Perlite Compaction in Large Cryogenic Tanks  

NASA Technical Reports Server (NTRS)

Perlite is the most typical insulating powder used to separate the inner and outer shells of cryogenic tanks. The inner tank holds the low-temperature commodity, while the outer shell is exposed to the ambient temperature. Perlite minimizes radiative energy transfer between the two tanks. Being a powder, perlite will settle over time, leading to the danger of transferring any loads from the inner shell to the outer shell. This can cause deformation of the outer shell, leading to damaged internal fittings. The method proposed is to place strain or displacement sensors on several locations of the outer shell. Loads induced on the shell by the expanding inner shell and perlite would be monitored, providing an indication of the location and degree of compaction.

Youngquist, Robert

2010-01-01

468

Divergence in male and female manipulative behaviors with the intensification of metallurgy in central europe.  

PubMed

Humeral morphology has been shown to reflect, in part, habitual manipulative behaviors in humans. Among Central European agricultural populations, long-term social change, increasing task specialization, and technological innovation all had the potential to impact patterns of habitual activity and upper limb asymmetry. However, systematic temporal change in the skeletal morphology of agricultural populations in this region has not been well-characterized. This study investigates diachronic patterns in humeral biomechanical properties and lengths among 174 adult Central European agriculturalists through the first ?5400 years of farming in the region. Greater asymmetry in biomechanical properties was expected to accompany the introduction of metallurgy, particularly in males, while upper limb loading patterns were expected to be more similar between the Bronze and Iron Ages. Results revealed a divergence in the lateralization of upper limb biomechanical properties by sex between the Early/Middle Neolithic and Early/Middle Bronze Age. Neolithic females had significantly more variable properties than males in both humeri, while Bronze Age female properties became homogeneous and very symmetrical relative to the right-biased lateralization of contemporaneous males. The Bronze Age to Iron Age transition was associated with morphological change among females, with a significant increase in right-biased asymmetry and a concomitant reduction in sexual dimorphism. Relative to biomechanical properties, humeral length variation and asymmetry were low though some significant sexual dimorphism and temporal change was found. It was among females that the lateralization of humeral biomechanical properties, and variation within them, changed most profoundly through time. This suggests that the introduction of the ard and plow, metallurgical innovation, task specialization, and socioeconomic change through ?5400 years of agriculture impacted upper limb loading in Central European women to a greater extent than men. PMID:25389972

Macintosh, Alison A; Pinhasi, Ron; Stock, Jay T

2014-01-01

469

MHD-units of a magnetodynamic type, used in technological processes for metallurgy and casting production  

SciTech Connect

In many technological processes for casting production and in metallurgy, a forced action on liquid metal must be combined with its pre-heating. Under these conditions MHD-pumps and units of a magneto-dynamic type (MDN), which is a separate class of a pulsing type field of induction MHD-machines of a pulsing field, have essential advantages in comparison with other MHD-machines and known mechanical units, as they possess a high hydrothermal efficiency and the opportunity to change the correlation between hydraulic and heat parameters within wide limits. Since 1961 year there have been developed more than 30 types of MDN. Using the units MDN-3, MDN-6 and MDN-17, the analysis of main peculiarities of this type of MHD-machines has been carried out. A Working Zone (WZ) of MDN is a hydraulic manifold, created by a circular channel and branching-off it or crossing it by the conduit. Here, the current, induced in the liquid metal, by the closed electromagnetic system- an inductor, - interacts with a transverse magnetic field, created by the electromagnet, in the gap of which is WZ. The peculiarities of a metal flow and distribution of pressure in WZ of MDN, which have a T-joined and a cross-shaped form, are being considered here: generation of vortices in the regions of a drop of a magnetic field along the sides of WZ, appearance of reduced pressure regions. In this report there are being considered the different schemes of MDN application in casting and metallurgical production: for melting, preparing and refining treatment of metal, conveying and batchering, forced feeding of moulds and crystallization under electromagnetic pressure, given are the characteristics of industrial, including serially produced, MDN for non-ferrous alloys and iron.

Tsin, M.R.; Dubodelov, V.I.

1995-12-31

470

Combustion of Na 2B 4O 7 + Mg + C to synthesis B 4C powders  

NASA Astrophysics Data System (ADS)

Boron carbide powder was fabricated by combustion synthesis (CS) method directly from mixed powders of borax (Na 2B 4O 7), magnesium (Mg) and carbon. The adiabatic temperature of the combustion reaction of Na 2B 4O 7 + 6 Mg + C was calculated. The control of the reactions was achieved by selecting reactant composition, relative density of powder compact and gas pressure in CS reactor. The effects of these different influential factors on the composition and morphologies of combustion products were investigated. The results show that, it is advantageous for more Mg/Na 2B 4O 7 than stoichiometric ratio in Na 2B 4O 7 + Mg + C system and high atmosphere pressure in the CS reactor to increase the conversion degree of reactants to end product. The final product with the minimal impurities' content could be fabricated at appropriate relative density of powder compact. At last, boron carbide without impurities could be obtained after the acid enrichment and distilled water washing.

Guojian, Jiang; Jiayue, Xu; Hanrui, Zhuang; Wenlan, Li

2009-09-01

471

Studies on Flowability, Compressibility and In-vitro Release ofTerminalia chebula Fruit Powder Tablets.  

PubMed

The dried fruit of Terminalia chebula is widely used for its laxative properties. The objective of the present study was to examine the flowability and compressibility of Terminalia chebula fruit powder, subsequently developing its tablet formulations by utilizing wet granulation and direct compression technology. Initial studies on flowability and compressibility revealed that the fruit powder flows poorly, is poorly compressible and mucilaginous in nature. The consolidation behaviors of the fruit powder and of its tablet formulations were studied using the Kawakita, Heckel and Leuenberger equations. Kawakita analysis revealed reduced cohesiveness hence improved flowability was achieved in formulations prepared by direct compression and the wet granulation technique. The Heckel plot showed that the Terminalia chebula fruit powder when formulated using direct compression showed initial fragmentation followed by plastic deformation and that the granules exhibited plastic deformation without initial fragmentation. The compression susceptibility parameter obtained from the Leuenberger equation for compacts formed by using the direct compression and wet granulation techniques indicated that the maximum crushing strength is reached faster and at lower compression pressures. The Tannin content (with reference to standard tannin) in fruit powder and tablet formulations was determined by UV spectrophotometry at 273 nm. The in-vitro dissolution study in simulated SGF (without enzymes) showed more than a 90% release of tannin from the tablets with in 1 h. The brittle fracture index value revealed that tablets prepared from granules showed less fracture tendency in comparison to those formed by direct compression formulation. From this study, it was concluded that the desired flowability, compressibility and compactibility of Terminalia chebula fruit powder can be obtained by using the direct compression and wet granulation techniques. PMID:24363675

Satya Prakash, Singh; Patra, Niranjan; Santanu, Chakraborty; Hemant Kumar, Pandit; Patro, Jagannath; Devi, Vimala

2011-01-01

472

Studies on Flowability, Compressibility and In-vitro Release of Terminalia Chebula Fruit Powder Tablets.  

PubMed

The dried fruit of Terminalia chebula is widely used for its laxative properties. The objective of the present study was to examine the flowability and compressibility of Terminalia chebula fruit powder, subsequently developing its tablet formulations by utilizing wet granulation and direct compression technology. Initial studies on flowability and compressibility revealed that the fruit powder flows poorly, is poorly compressible and mucilaginous in nature. The consolidation behaviors of the fruit powder and of its tablet formulations were studied using the Kawakita, Heckel and Leuenberger equations. Kawakita analysis revealed reduced cohesiveness hence improved flowability was achieved in formulations prepared by direct compression and the wet granulation technique. The Heckel plot showed that the Terminalia chebula fruit powder when formulated using direct compression showed initial fragmentation followed by plastic deformation and that the granules exhibited plastic deformation without initial fragmentation. The compression susceptibility parameter obtained from the Leuenberger equation for compacts formed by using the direct compression and wet granulation techniques indicated that the maximum crushing strength is reached faster and at lower compression pressures. The Tannin content (with reference to standard tannin) in fruit powder and tablet formulations was determined by UV spectrophotometry at 273 nm. The in-vitro dissolution study in simulated SGF (without enzymes) showed more than a 90% release of tannin from the tablets with in 1 h. The brittle fracture index value revealed that tablets prepared from granules showed less fracture tendency in comparison to those formed by direct compression formulation. From this study, it was concluded that the desired flowability, compressibility and compactibility of Terminalia chebula fruit powder can be obtained by using the direct compression and wet granulation techniques. PMID:24250371

Satya Prakash, Singh; Patra, Ch Niranjan; Santanu, Chakraborty; Hemant Kumar, Pandit; Patro, V Jagannath; Devi, M Vimala

2011-01-01

473

Use of first derivative of displacement vs. force profiles to determine deformation behavior of compressed powders.  

PubMed

Displacement (D) vs. force (F) profiles obtained during compaction of powders have been reported by several researchers. These profiles are usually used to obtain mechanical energies associated with the compaction of powders. In this work, we obtained displacement-force data associated with the compression of six powders; Avicel PH101, Avicel PH301, pregelatinized corn starch, anhydrous lactose, dicalcium phosphate, and mannitol. The first three powders are known to deform predominantly by plastic behavior while the later ones are known to deform predominantly by brittle fracture. Displacement-force data was utilized to perform in-die Heckel analysis and to calculate the first derivative (dD/dF) of displacement-force plots. First derivative results were then plotted against mean force (F') at each point and against 1/F' at compression forces between 1 and 20 kN. Results of the in-die Heckle analysis are in very good agreement with the known deformation behavior of the compressed materials. First derivative plots show that materials that deform predominantly by plastic behavior have first derivative values (0.0006-0.0016 mm/ N) larger than those of brittle materials (0.0004 mm/N). Moreover, when dD/dF is plotted against 1/F' for each powder, a linear correlation can be obtained (R2=>0.98). The slopes of the dD/dF vs. 1/F' plots for plastically deforming materials are relatively larger than those for materials that deform by brittle behavior. It is concluded that first derivative plots of displacement-force profiles can be used to determine deformation behavior of powders. PMID:23341076

Gharaibeh, Shadi F; Aburub, Aktham

2013-03-01

474

Compact multiframe blind deconvolution.  

PubMed

We describe a multiframe blind deconvolution (MFBD) algorithm that uses spectral ratios (the ratio of the Fourier spectra of two data frames) to model the inherent temporal signatures encoded by the observed images. In addition, by focusing on the separation of the object spectrum and system transfer functions only at spatial frequencies where the measured signal is above the noise level, we significantly reduce the number of unknowns to be determined. This "compact" MFBD yields high-quality restorations in a much shorter time than is achieved with MFBD algorithms that do not model the temporal signatures; it may also provide higher-fidelity solutions. PMID:21403711

Hope, Douglas A; Jefferies, Stuart M

2011-03-15

475

Compact LINAC for deuterons  

SciTech Connect

We are developing a compact deuteron-beam accelerator up to the deuteron energy of a few MeV based on room-temperature inter-digital H-mode (IH) accelerating structures with the transverse beam focusing using permanent-magnet quadrupoles (PMQ). Combining electromagnetic 3-D modeling with beam dynamics simulations and thermal-stress analysis, we show that IHPMQ structures provide very efficient and practical accelerators for light-ion beams of considerable currents at the beam velocities around a few percent of the speed of light. IH-structures with PMQ focusing following a short RFQ can also be beneficial in the front end of ion linacs.

Kurennoy, S S [Los Alamos National Laboratory; O' Hara, J F [Los Alamos National Laboratory; Rybarcyk, L J [Los Alamos National Laboratory

2008-01-01

476

Cross-interaction of under-bump metallurgy and surface finish in flip-chip solder joints  

Microsoft Academic Search

The cross-interaction of the under-bump metallurgy (UBM)\\/solder interface and the solder\\/surface-finish interface in flip-chip\\u000a solder joints was investigated. In this study, the UBM on the chip side was a single layer of Cu (8.5 m), and the surface\\u000a finish on the substrate side was a 0.2-m Au layer over 5-m Ni. It was shown that, after two reflows, the Ni

C. M. Tsai; W. C. Luo; C. W. Chang; Y. C. Shieh; C. R. Kao

2004-01-01

477

Thermal fatigue properties of lead-free solders on Cu and NiP under bump metallurgies  

Microsoft Academic Search

Three Pb-free solders, SnCu0.7, SnAg3.8Cu0.7 and SnAg3.5 were evaluated on both electroless NiP and electroplated Cu under bump metallurgies (UBM) for flip chip applications. Eutectic SnPb37 solder was also evaluated as a baseline comparison with the Pb-free solders. Test dice with a size of 12.6×7.5 mm2 were direct flip chip attached to test boards with variety of solder alloy\\/UBM combinations.

Charles Zhang; Jong-Kai Lin; Li Li

2001-01-01

478

Powder injection molding of a 17-4 PH stainless steel and the effect of sintering temperature on its microstructure and mechanical properties  

Microsoft Academic Search

The 17-4 PH stainless steel powders with average diameter of 10?m were injection-molded into plate-type tensile specimens. Sintering of the compacts was carried out at the various temperatures ranging from 900 to 1350°C after solution extraction and thermal decomposition. Sintering behavior of the powder injection-molded specimens and room temperature tensile properties of sintered specimens were investigated. With increase in the

Hwan-Jin Sung; Tae Kwon Ha; Sangho Ahn; Young Won Chang

2002-01-01

479

Sonocrystallization yields monoclinic paracetamol with significantly improved compaction behavior.  

PubMed

Ultrasound-assisted crystallization (sonocrystallization) was used to prepare a mixture of nano- and micrometer-sized crystals of the monoclinic form of paracetamol-a widely used analgesic known for its particularly problematic mechanical behavior under compression (i.e. poor tabletability). The nano- and micrometer-sized crystals yielded a powder which exhibits elastic moduli and bulk cohesions that are significantly higher than those observed in samples consisting of macrometer-sized crystals, thus leading to enhanced tabletability without the use of excipients, particle coating, salt, or cocrystal formation. Experimental compaction and finite element analysis were utilized to rationalize the significantly improved compaction behavior of the monoclinic form of paracetamol. PMID:25370777

Bu?ar, Dejan-Krešimir; Elliott, James A; Eddleston, Mark D; Cockcroft, Jeremy K; Jones, William

2015-01-01

480

Compact electrostatic comb actuator  

DOEpatents

A compact electrostatic comb actuator is disclosed for microelectromechanical (MEM) applications. The actuator is based upon a plurality of meshed electrostatic combs, some of which are stationary and others of which are moveable. One or more restoring springs are fabricated within an outline of the electrostatic combs (i.e. superposed with the moveable electrostatic combs) to considerably reduce the space required for the actuator. Additionally, a truss structure is provided to support the moveable electrostatic combs and prevent bending or distortion of these combs due to unbalanced electrostatic forces or external loading. The truss structure formed about the moveable electrostatic combs allows the spacing between the interdigitated fingers of the combs to be reduced to about one micron or less, thereby substantially increasing the number of active fingers which can be provided in a given area. Finally, electrostatic shields can be used in the actuator to substantially reduce unwanted electrostatic fields to further improve performance of the device. As a result, the compact electrostatic comb actuator of the present invention occupies only a fraction of the space required for conventional electrostatic comb actuators, while providing a substantial increase in the available drive force (up to one-hundred times).

Rodgers, M. Steven (Albuquerque, NM); Burg, Michael S. (Albuquerque, NM); Jensen, Brian D. (Albuquerque, NM); Miller, Samuel L. (Albuquerque, NM); Barnes, Stephen M. (Albuquerque, NM)

2000-01-01