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1

Ultrasonic Fatigue Behavior of a Fe-BASED Warm-Compacted Powder Metallurgy Material  

NASA Astrophysics Data System (ADS)

Fe-2Cu-2Ni-1Mo-1C powder metallurgy material was fabricated by die-wall lubricated warm compaction and ultrasonic fatigue test was carried out for as-sintered and heat treatment samples. Material fatigue strength reaches 249 MPa under axial fatigue testing. The sintered material consists of acicular martensite, pearlite, bainite and retained austenite. Tempered martensite is the major phases after heat-treatment. Cleavage plane and dimples is mixed fracture for sample after axial fatigue test. Mechanical properties of after heat treatment materials are improved and fatigue strength reaches 382 MPa under 107 cycles in bending ultrasonic fatigue test. The fatigue strength increases significantly in high cycles range.

Lu, Yu-Heng; Ye, Xuan; Hu, Lei; Luo, Fei; Xiao, Zhi-Yu

2013-07-01

2

Biaxially textured articles formed by powder metallurgy  

DOEpatents

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

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

2003-08-05

3

Biaxially textured articles formed by powder metallurgy  

DOEpatents

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

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

2004-09-28

4

Biaxially textured articles formed by powder metallurgy  

DOEpatents

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

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

2003-08-19

5

Biaxially textured articles formed by powder metallurgy  

DOEpatents

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

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

2003-08-26

6

Biaxially textured articles formed by powder metallurgy  

DOEpatents

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

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

2005-06-07

7

Biaxially textured articles formed by powder metallurgy  

DOEpatents

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

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

2004-09-14

8

Biaxially textured articles formed by powder metallurgy  

DOEpatents

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

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

2005-01-25

9

Biaxially textured articles formed by powder metallurgy  

DOEpatents

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

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

2005-05-10

10

Biaxially textured articles formed by powder metallurgy  

DOEpatents

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

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

2003-07-29

11

Powder metallurgy in 1995  

SciTech Connect

The powder metallurgy industry has enjoyed extraordinary growth during the last three years, based on progress in materials, processes, and equipment. Total metal powder shipments increased 18% in 1994 to 426,050 tons. For the first time, North American iron powder shipments went beyond 338,000 tons in 1994, a 17.4% increase over 1993. The copper and copper-base powder markets in 1994 reached 23,000 tons, growing slightly less than 3% over 1993. The parts segment of this market reached 19,670 tons, almost flat with 1993 because of the sharply rising price of copper on world commodity markets. This article will discuss advances in steel powders and processing, the range of iron powder applications, advanced particulate materials, equipment improvements, and standards development.

White, D.G. [Metal Powder Industries Federation, Princeton, NJ (United States)

1995-08-01

12

Modern developments in powder metallurgy  

SciTech Connect

This book presents the papers given at a conference on metal powders. Topics considered at the conference included sintering fundamentals, liquid phase and activated sintering, stainless steels, copper-base powder metallurgy, aluminium alloys, refractory metals, carbides, cutting tools, friction, wear, and powder production.

Aqua, E.N.; Whitman, C.I.

1984-01-01

13

Aluminum powder metallurgy processing  

SciTech Connect

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

Flumerfelt, J.F.

1999-02-12

14

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

15

Biaxially textured articles formed by powder metallurgy  

DOEpatents

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

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

2003-10-21

16

A major advance in powder metallurgy  

NASA Technical Reports Server (NTRS)

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

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

1991-01-01

17

Volume 7. Copper base powder metallurgy  

Microsoft Academic Search

This book is based on a series of lectures on copper and copper base P\\/M materials sponsored by the Metal Powder Industries Federation. It covers recent developments in the fields of copper powder metallurgy and offers a comprehensive survey of copper and copper-base P\\/M materials. It begins with a chapter on the production of copper and copper alloy powders followed

Taubenblat

1980-01-01

18

Advances in powder metallurgy of soft magnetic materials  

Microsoft Academic Search

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

Christopher G. Oliver

1995-01-01

19

Powder metallurgy design manual, 2nd edition  

SciTech Connect

This book is the most concise and comprehensive book of its kind on powder metallurgy (P/M) technology for both component design and application. Completely updated from the previous edition, this valuable reference gives an entirely new coverage on metal injection molding (MIM) and powder forging (P/F) with applicable case histories. There is revised information on P/M compared with other technologies, prototyping, and properties and characteristics of alloys, powders and P/M materials. In addition there`s expanded data on sintering including liquid phase processing and hardening.

NONE

1995-12-31

20

Evaluation of powder metallurgy superalloy disk materials  

NASA Technical Reports Server (NTRS)

A program was conducted to develop nickel-base superalloy disk material using prealloyed powder metallurgy techniques. The program included fabrication of test specimens and subscale turbine disks from four different prealloyed powders (NASA-TRW-VIA, AF2-1DA, Mar-M-432 and MERL 80). Based on evaluation of these specimens and disks, two alloys (AF2-1DA and Mar-M-432) were selected for scale-up evaluation. Using fabricating experience gained in the subscale turbine disk effort, test specimens and full scale turbine disks were formed from the selected alloys. These specimens and disks were then subjected to a rigorous test program to evaluate their physical properties and determine their suitability for use in advanced performance turbine engines. A major objective of the program was to develop processes which would yield alloy properties that would be repeatable in producing jet engine disks from the same powder metallurgy alloys. The feasibility of manufacturing full scale gas turbine engine disks by thermomechanical processing of pre-alloyed metal powders was demonstrated. AF2-1DA was shown to possess tensile and creep-rupture properties in excess of those of Astroloy, one of the highest temperature capability disk alloys now in production. It was determined that metallographic evaluation after post-HIP elevated temperature exposure should be used to verify the effectiveness of consolidation of hot isostatically pressed billets.

Evans, D. J.

1975-01-01

21

Volume 7. Copper base powder metallurgy  

SciTech Connect

This book is based on a series of lectures on copper and copper base P/M materials sponsored by the Metal Powder Industries Federation. It covers recent developments in the fields of copper powder metallurgy and offers a comprehensive survey of copper and copper-base P/M materials. It begins with a chapter on the production of copper and copper alloy powders followed by discussions of specific applications of P/M materials in bronzes and bearings, in brasses and nickel silvers, and in electrically conductive parts. Also discussed are iron composition containing copper, copper-based alloys for infiltration of iron and other special copper-base alloys. It concludes with chapters on consolidation, sintering and review of specifications.

Taubenblat, P.W. (ed.)

1980-01-01

22

Low-Cobalt Powder-Metallurgy Superalloy  

NASA Technical Reports Server (NTRS)

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

Harf, F. H.

1986-01-01

23

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

24

An application of powder metallurgy to dentistry.  

PubMed

Generally, the dental casting method is used to fabricate dental prostheses made with metal. The method of fabricating dental prostheses from sintered titanium alloy has certain advantages: the elimination of casting defects, a sintering temperature that is lower than the melting point, and a shorter processing time. By examining (1) the properties of green, sintered compacts of titanium powder, (2) the effects of adding aluminum powder on the properties of green, sintered compacts of Ti-Al compound, and (3) the effects of adding copper powder on the properties of green, sintered compacts of Ti-Al-Cu compound, the authors developed a sintered titanium alloy on a trial basis. Because the properties satisfied the requirements of dental restorations, a powder metallurgical method of making dental restorations from this sintered titanium alloy was devised. Applications of such sintered titanium alloys for the metal coping of metal-ceramic crowns and denture base plates were discussed. PMID:8689755

Oda, Y; Ueno, S; Kudoh, Y

1995-11-01

25

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

SciTech Connect

The present volume powder metallurgy materials discusses the state of the PM industry, a metallurgical evaluation of new steel powders, design criteria for the manufacturing of low-alloy steel powders, and homogenization processing of a PM maraging steel. Attention is given to the corrosion resistance of full density sintered 316 SS, the performance characteristics of a new sinter-hardening low-alloy steel, wear performance of compositions made by low alloy iron/high alloy powder mixtures, and the strengthening of an AISI 1020 steel by aluminum-microalloying during liquid dynamic compaction. Topics addressed include the influence of alloying on the properties of water-atomized copper powders, fundamentals of high pressure gas atomization process control, advanced sensors and process control of gas atomization, and bimetallic tubulars via spray forming. Also discussed are factors affecting the delamination of PM molybdenum during stamping, applications of powder metallurgy molybdenum in the 1990s, and powder processing of high-temperature oxides.

Pease, L.F. III; Sansoucy, R.J.

1991-01-01

26

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

27

Si Alloys Produced by Powder Metallurgy  

NASA Astrophysics Data System (ADS)

The present paper deals with the properties of bulk nanostructured Al-Fe-V-Si alloys containing 16, 27, and 37 vol.% of Al12(Fe,V)3Si precipitates. The elemental powders were subjected to high-energy ball milling for 60 h followed by hot-pressing in a uniaxial die at 550 C under 300 MPa. Mechanical properties of consolidated samples were evaluated by hardness, room temperature, and high temperature compression tests and compared with those of rapid solidification-powder metallurgy (RS-PM) counterparts and also those available for conventional and high temperature Al alloys. The results showed that the nanostructured alloy containing Al12(Fe,V)3Si precipitates has good thermal stability at high temperatures. Room temperature compression tests demonstrated that the strength increases and the ductility decreases with increasing the volume percentage of Al12(Fe,V)3Si precipitates. The room temperature yield strength of nanostructured alloys was in the range of 560-758 MPa depending on Al12(Fe,V)3Si content. These values are much higher than those for RS-PM counterparts. In addition, nanostructured Al-Al12(Fe,V)3Si alloys exhibited better strength at elevated temperatures compared with other Al alloys.

Ashrafi, H.; Enayati, M. H.; Emadi, R.

2014-05-01

28

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

Microsoft Academic Search

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

L. Ma. Flores-Vlez; J. Chvez; L. Hernndez; O. Domnguez

2001-01-01

29

Properties of duplex stainless steels made by powder metallurgy  

Microsoft Academic Search

Purpose: of this paper was to examine the mechanical properties of duplex stainless steels. Design\\/methodology\\/approach: In presented study duplex stainless steels were obtained through powder metallurgy starting from austenitic, martensitic base powders by controlled addition of alloying elements, such as Cr, Ni, Mo and Cu. In the studies behind the preparation of mixes, Schaeffler's diagram was taken into consideration. Prepared

L. A. Dobrzaski; Z. Brytan; M. Actis Grande; M. Rosso

30

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

31

Use of SV-type jigging screens in powder metallurgy  

Microsoft Academic Search

Jigging screens of the SV type are widely used in powder metallurgy. The specifications of these screens are shown in Table 1. A distinctive feature of their operation is the character of vibration of the screening surfaces: in contrast to other designs of vibrating screens -- which employ directional or circular modes of vibration -- the given design uses threecomponent

V. N. Troitskii; A. Yu. Brodskii

1996-01-01

32

Near-Net Shape Powder Metallurgy Rhenium Thruster  

NASA Technical Reports Server (NTRS)

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

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

2001-01-01

33

Laboratory Powder Metallurgy Makes Tough Aluminum Sheet  

NASA Technical Reports Server (NTRS)

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

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

1993-01-01

34

Milling and Drilling Evaluation of Stainless Steel Powder Metallurgy Alloys  

SciTech Connect

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

Lazarus, L.J.

2001-12-10

35

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, ..

2014-11-01

36

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

37

Advanced powder metallurgy aluminum alloys via rapid solidification technology  

NASA Technical Reports Server (NTRS)

Aluminum alloys containing 10 to 11.5 wt. pct. of iron and 1.5 to 3 wt. pct. of chromium using the technique of rapid solidification powder metallurgy were studied. Alloys were prepared as thin ribbons (.002 inch thick) rapidly solidified at uniform rate of 10(6) C/second by the melt spinning process. The melt spun ribbons were pulverized into powders (-60 to 400 mesh) by a rotating hammer mill. The powders were consolidated by hot extrusion at a high reduction ratio of 50:1. The powder extrusion temperature was varied to determine the range of desirable processing conditions necessary to yield useful properties. Powders and consolidated alloys were characterized by SEM and optical metallography. The consolidated alloys were evaluated for (1) thermal stability, (2) tensile properties in the range, room temperature to 450 F, and (3) notch toughness in the range, room temperature to 450 F.

Ray, R.

1984-01-01

38

Modulus Dependence on Large Scale Porosity of Powder Metallurgy Steel  

NASA Astrophysics Data System (ADS)

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

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

2012-07-01

39

Microstructure and Aging of Powder-Metallurgy Al Alloys  

NASA Technical Reports Server (NTRS)

Report describes experimental study of thermal responses and aging behaviors of three new aluminum alloys. Alloys produced from rapidly solidified powders and contain 3.20 to 5.15 percent copper, 0.24 to 1.73 percent magnesium, 0.08 to 0.92 percent iron, and smaller amounts of manganese, nickel, titanium, silicon, and zinc. Peak hardness achieved at lower aging temperatures than with standard ingot-metallurgy alloys. Alloys of interest for automobile, aircraft, and aerospace applications.

Blackburn, L. B.

1987-01-01

40

Numerical Simulation on Pharmaceutical Powder Compaction Lianghao Han1,a  

E-print Network

Department of Materials Science and Metallurgy, University of Cambridge, CB2 3QZ,UK 2 Pfizer Global R the elastic recovery of powders during unloading and after ejection. This is particularly important, since the elastic recovery may produce catastrophic flaws and initiate the cracks within compacts, causing

Elliott, James

41

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

42

Ti matrix syntactic foam fabricated by powder metallurgy: Particle breakage and elastic modulus  

NASA Astrophysics Data System (ADS)

Titanium matrix syntactic foams have potential for orthopedic applications because of their good biocompatibility, corrosion resistance and ability of varying the elastic modulus. This paper studies the fabrication of Ti matrix syntactic foams embedded with ceramic microspheres (CMs) by a powder metallurgy method. The percentage of the crushed CMs during compaction was measured by the volume measurement and water absorption methods, and the elastic modulus of the Ti matrix syntactic foam was measured by compression tests. The effects of the Ti volume percentage and the compaction pressure on the percentage of crushed CMs and the elastic modulus were studied. For a given Ti volume percentage, the percentage of crushed CMs increases with increasing compaction pressure; for a given compaction pressure, the percentage of crushed CMs decreases with increasing Ti volume percentage. At a compaction pressure lower than 100 MPa, the elastic modulus increases with increasing Ti volume percentage and compaction pressure; at a compaction pressure above 100 MPa, further increases in Ti volume percentage and compaction pressure decrease the elastic modulus.

Xue, Xiaobing; Zhao, Yuyuan

2011-02-01

43

Phase Stability of a Powder Metallurgy Disk Superalloy  

NASA Technical Reports Server (NTRS)

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

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

2006-01-01

44

N18, Powder metallurgy superalloy for disks: Development and applications  

NASA Astrophysics Data System (ADS)

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 appro-priate 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 micro-structural instability. Further improvements in creep and crack propagation properties, without signifi-cant 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 Astroloy and is therefore an excellent alloy for modern turbine disk ap-plications.

Guedou, J. Y.; Lautridou, J. C.; Honnorat, Y.

1993-08-01

45

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

46

Mesoscale Simulations of Powder Compaction  

NASA Astrophysics Data System (ADS)

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

2009-12-01

47

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

48

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

49

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

50

Metallographic preparation of pressed and sintered powder-metallurgy material (tungsten, niobium, lead, and copper)  

Microsoft Academic Search

An object of this invention is to provide a metallographic preparation procedure for obtaining a flat and scratch-free surface of a representative sample of a pressed and sintered powder-metallurgy material. A further object of this invention is to provide a metallographic preparation procedure for obtaining a flat and scratch-free surface of a representative sample of a pressed and sintered powder-metallurgy

1987-01-01

51

Mesoscale simulations of powder compaction  

NASA Astrophysics Data System (ADS)

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 experimental match 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 evidence of hard-to-explain reshock states above the single-shock Hugoniot line, which have also been observed in the experiments. We found that to receive good quantitative agreement with experiment it is essential to perform 3D simulations, since 2D results tend to underpredict stress levels for high-porosity powders regardless of material properties. We developed a process to extract macroscale information for the simulation which can be directly used in calibration of continuum model for heterogeneous media.

Lomov, Ilya; Antoun, Tarabay; Liu, Benjamin

2009-06-01

52

Some features on hot forging of powder metallurgy sintered high strength 4%titanium carbide composite steel preforms under different stress state conditions  

Microsoft Academic Search

In this paper, the authors propose mathematical expressions for the determination of different stress ratio parameters under plane and triaxial stress state conditions. Experiments were carried out to evaluate the hot forging features in the high strength sintered powder metallurgy 4%titanium carbide composite steel performs under different stress states, namely, plane stress and triaxial stress states. Cylindrical compacts with aspect

R. Narayanasamy; V. Senthilkumar; K. S. Pandey

2008-01-01

53

Testing of electroformed deposited iridium/powder metallurgy rhenium rockets  

NASA Technical Reports Server (NTRS)

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

Reed, Brian D.; Dickerson, Robert

1996-01-01

54

Elevated temperature crack growth in advanced powder metallurgy aluminum alloys  

NASA Technical Reports Server (NTRS)

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

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

1990-01-01

55

High strength bulk Fe-Co alloys produced by powder metallurgy  

SciTech Connect

Fe-Co alloys are extensively used in lamination form, but there are certain power generation applications that require Fe-Co rotors in bulk form. Experiencing only a dc magnetic field, these rotors can be as large as 0.5 m in diameter, depending on the size of the generator. The forging of such large pieces of Fe-Co has proven to be difficult. The present study investigates powder metallurgy processing of a gas atomized FeCoNbV alloy through hot isostatic pressing (HIP) for manufacturing large size rotors with improved mechanical strength. Gas atomized FeCoNbV alloy powders with and without ball milling were hot isostatic pressed at temperatures between 675 and 850 deg. C at a fixed pressure of 193 MPa for up to 6 h. Ball milling prior to HIP improved the yield strength. A further improvement in yield strength and in ductility was obtained after a disordering heat treatment at 730 deg. C followed by a rapid quench to room temperature. The optimum HIP and annealing conditions resulted in samples with yield strengths of 870 MPa. The compacts exhibited average coercivity values of 6.4 Oe and maximum permeability values of 1100.

Turgut, Zafer; Huang Meiqing [UES Inc., 4401 Dayton-Xenia Rd., Dayton Ohio 45432 (United States); AFRL, Wright-Patterson AFB, Ohio 45433 (United States); Horwath, John C.; Fingers, Richard T. [AFRL, Wright-Patterson AFB, Ohio 45433 (United States)

2008-04-01

56

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

57

FEA model for predicting the response of powder metallurgy steel components to heat treatment  

Microsoft Academic Search

A model and the necessary database for predicting the response of powder metallurgy steels to heat treatment are presented and discussed. The model is based on a modification of the commercially available software DANTE coupled to the finite element analysis software ABAQUS. The model requires an extensive database that includes temperature- and porosity-dependent phase transformation kinetics, and temperature- and porosity-dependent

Virendra S. Warke; Richard D. Sisson Jr.; Makhlouf M. Makhlouf

2009-01-01

58

Powder metallurgy in aerospace structural applications---Current use and future trends  

SciTech Connect

The major role played by materials in providing advances in systems performance as we move towards the twenty-first century is reviewed. Specific developments in the powder metallurgy/rapid solidification of alloys, based on aluminum, magnesium, titanium, niobium, and copper are discussed in detail. 47 refs., 12 figs.

Froes, F.H.; Rowe, R.G.; Das, S.K.; Stephens, J.J.

1989-06-09

59

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

NASA Technical Reports Server (NTRS)

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

Harf, Fredric H.

1989-01-01

60

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 Andr; Rodrigues Henriques; Carlos Alberto; Alves Cairo

2005-01-01

61

Processing of M2 powder metallurgy high-speed steel by means of starch consolidation  

Microsoft Academic Search

A study is made of a new method called starch consolidation (SC) for the production of powder metallurgy (P\\/M) high-speed steel (HSS) components. Samples of a commercial HSS, M2, were shaped by using 1.5, 3.5 and 5vol% of starch and up to 60vol% of powder. The high solids loading was made possible by a small addition (0.03wt%) of dispersant (polyacrylic

P. Romano; F. J. Velasco; J. M. Torralba; N. Candela

2006-01-01

62

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, Mikls; Markos, Sndor; Farkas, Balzs

2012-09-01

63

Properties of WZ21 (%wt) alloy processed by a powder metallurgy route.  

PubMed

Microstructure, mechanical properties and corrosion behaviour of WZ21 (%wt) alloy prepared by a powder metallurgy route from rapidly solidified powders have been studied. Results were compared to those of the same alloy prepared through a conventional route of casting and extrusion. The microstructure of the extruded ingot consisted of ?-Mg grains and Mg3Zn3Y2 (W-phase) and LPSO-phase particles located at grain boundaries. Moreover, stacking faults were also observed within ?-Mg grains. The alloy processed by the powder metallurgy route exhibited a more homogeneous and finer microstructure, with a grain size of 2?m. In this case W-phase and Mg24Y5 phase were identified, but not the LPSO-phase. The microstructural refinement induced by the use of rapidly solidified powders strengthened the alloy at room temperature and promoted superplasticity at higher strain rates. Corrosion behaviour in PBS medium evidenced certain physical barrier effect of the almost continuous arrangements of second phases aligned along the extrusion direction in conventionally processed WZ21 alloy, with a stable tendency around 7mm/year. On the other hand, powder metallurgy processing promoted significant pitting corrosion, inducing accelerated corrosion rate during prolonged immersion times. PMID:25792409

Cabeza, Sandra; Garcs, Gerardo; Prez, Pablo; Adeva, Paloma

2015-06-01

64

Biaxially textured articles formed by power metallurgy  

DOEpatents

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

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

2003-08-26

65

Porous mandrels provide uniform deformation in hydrostatic powder metallurgy  

NASA Technical Reports Server (NTRS)

Porous copper mandrels prevent uneven deformation of beryllium machining blanks. The beryllium powder is arranged around these mandrels and hot isostatically pressed to form the blanks. The mandrels are then removed by leaching.

Gripshover, P. J.; Hanes, H. D.

1967-01-01

66

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

67

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

NASA Technical Reports Server (NTRS)

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

Herbell, T. P.

1972-01-01

68

Heat treatment effects on mechanical behavior of copper-nickel-tin produced via powder metallurgy  

Microsoft Academic Search

Certain spring applications require a material with a combination of high strength, stiffness, and electrical conductivity. An alloy, Cu-15wt%Ni-8wt%Sn, formed via a powder metallurgy process, is one of several copper-based alloys which can be heat treated\\/processed to form a metallic nano-structured alloy with good combinations of yield strength and electrical conductivity. For certain heat treatment conditions, this alloy decomposes spinodally

Joshua Benjamin Caris

2007-01-01

69

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

70

Powder metallurgy of Ge, Si, and Ge-Si  

NASA Astrophysics Data System (ADS)

id="ab1"Planetary ball-milling and pressing behaviour of Ge, Si and Ge-Si powder mixtures are investigated. Scanning and transmission electron microscopy observations revealed the different microstructure of the two elements after milling: Ge remains in a microcrystalline state, whereas Si can be comminuted into grains consisting of nanocrystalline regions. Planetary milling of the two elements together, using agate balls and vial, did not reveal any compound formation. By hot-isostatic pressing, pure Ge and Ge-Si mixtures were densified to a higher value than pure Si. This denotes a plastic flow of the Ge component at a process temperature of 800C. The microhardness of hot-pressed Ge reaches the bulk value; hot-pressed Si is very soft. Energy dispersive X-ray analysis and X-ray diffraction did not detect any impurity contamination from vial and milling media wear. Moreover, by electrical transport measurements it turned out that the net carrier concentration density resulting from electrical active impurities introduced by the milling and pressing process is below 2 x 1016 cm 3 at room temperature.

Schilz, Jrgen; Langenbach, Marion

1993-03-01

71

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

72

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, Aurlien; Tribet, Magaly; Leorier, Caroline; Delahaye, Thibaud; Donnet, Louis; Dehaudt, Philippe

2012-01-01

73

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

NASA Technical Reports Server (NTRS)

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

Piascik, Robert S.; Newman, John A.

2002-01-01

74

Preparation of Cu and Fly Ash Composite by Powder Metallurgy Technique  

Microsoft Academic Search

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

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

2011-01-01

75

Preparation of Cu and Fly Ash Composite by Powder Metallurgy Technique  

Microsoft Academic Search

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 1015 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

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

2011-01-01

76

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

77

Microstructure and mechanical behavior of 6061Al reinforced with silicon nitride particles, processed by powder metallurgy  

SciTech Connect

A critical step in the processing of Metal Matrix Composites (MMCs) reinforced with ceramic particles is the insertion of these particles into the metal matrix alloy. This greatly influences the strength of the composite since it is controlled by the metal-particle interfacial bond strength. Because of the difficulty in wetting ceramic particles with molten metal, the Powder Metallurgy or PM route was developed. Powder Extrusion consolidates the composite to over 98% dense, and can be carried out below the Solidus Temperature of the alloy. The most important aspect of the microstructure is the distribution of the reinforcing particles, and this depends on the processing and fabrication routes involved, as well as the relative size of the matrix and reinforcing particles. Extrusion can homogenize the structure to some extent, but minimizing reinforcement inhomogeneity during initial processing is important to achieve optimum properties.

Amigo, V.; Ortiz, J.L.; Salvador, M.D.

2000-01-31

78

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

NASA Technical Reports Server (NTRS)

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

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

1980-01-01

79

Effect of extrusion temperature on the microstructure of a powder metallurgy TiAl-based alloy  

SciTech Connect

In order to balance low temperature ductility, fracture toughness and high temperature properties of {gamma}-TiAl aluminide alloys, recent developments of the alloys have focused on refining the {gamma}/{alpha}{sub 2} full lamellar (FL) microstructure through advanced processing such as powder metallurgy (P/M). Resulted from a refined FL microstructure (both smaller lamellar grain size and thinner lamellar interface spacing) in the P/M fabricated titanium aluminide alloys, the mechanical properties of the alloys have been demonstrated to be superior to those of the aluminide alloys fabricated by conventional ingot metallurgy (I/M). However, since the microstructure of rapidly-solidified aluminide powder used in P/M process is not in an equilibrium state, the microstructures of P/M aluminide alloys are expected to be sensitive to the processing history. Accordingly, the optimization of microstructure-property of a P/M alloy through an appropriate P/M process control becomes an important issue. The purpose of this investigation is therefore aiming at understanding the effect of extrusion temperature on the microstructure of a P/M titanium aluminide alloy.

Hsiung, L.M.; Nieh, T.G. [Lawrence Livermore National Lab., CA (United States)] [Lawrence Livermore National Lab., CA (United States); Clemens, D.R. [Pratt and Whitney, West Palm Beach, FL (United States). Advanced Engineering Operations] [Pratt and Whitney, West Palm Beach, FL (United States). Advanced Engineering Operations

1997-01-15

80

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

NASA Technical Reports Server (NTRS)

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

Kent, W. B.

1977-01-01

81

A probabilistic method for the fatigue life assessment of powder metallurgy parts of aircraft engines  

SciTech Connect

This paper will present a probabilistic approach developed in order to assess the fatigue life of aircraft engine parts (turbine disks) obtained by powder metallurgy technique. First of all, the main issues will be pointed out and the theoretical principles of the method will be described. Then the design implications and the experimental correlation will be emphasized. The scale effect is a major concern for the fatigue life assessment of a powder metallurgy part. It no longer allows the designer to evaluate the life of a massive part directly from experimental results based on small specimen fatigue tests as is done in the classical methodology. In order to describe this scale effect correctly, incubation sites (inhomogeneities like ceramic inclusions) must be characterized. The size of these inhomogeneities and their positions in the part appeared to be the most relevant parameters. Hence the methodology developed at SNECMA integrates the scale effect scatter through a binomial probability distribution as well as a temperature and stress-dependent life evaluation for each inhomogeneity size and position. The life calculation of a part implies an analysis of its whole volume and surface. An iterative process determines the number of cycles corresponding to a global reliability level requirement for the part. The complete methodology is then validated by comparing the calculated initiation distribution with experimental results on small specimens and test disks.

Krafft, R.; Mosset, S. [SNECMA, Moissy-Cramayel (France)

1996-04-01

82

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

PubMed

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

Capek, Jaroslav; Vojt?ch, Dalibor

2014-10-01

83

Assessment of Low Cycle Fatigue Behavior of Powder Metallurgy Alloy U720  

NASA Technical Reports Server (NTRS)

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

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

2000-01-01

84

Compacting Plastic-Bonded Explosive Molding Powders to Dense Solids  

SciTech Connect

Dense solid high explosives are made by compacting plastic-bonded explosive molding powders with high pressures and temperatures for extended periods of time. The density is influenced by manufacturing processes of the powders, compaction temperature, the magnitude of compaction pressure, pressure duration, and number of repeated applications of pressure. The internal density variation of compacted explosives depends on method of compaction and the material being compacted.

B. Olinger

2005-04-15

85

The combination of precipitation and dispersion hardening in powder metallurgy produced Cu-Ti-Si alloy  

SciTech Connect

Microstructure and microhardness properties of precipitation hardened Cu-Ti and precipitation/dispersion hardened Cu-Ti-Si alloys have been analyzed. Cu-1.2Ti and Cu-1.2Ti-3TiSi{sub 2} (wt.%) atomized powders were characterized before and after consolidation by HIP (Hot Isostatic Pressing). Rapidly solidified powders and HIP-ed compacts were subsequently subjected to thermal treatment in hydrogen at temperatures between 300 and 600 deg. C. Compared to Cu-Ti powder particles and compacts, obtained by the same procedure, the strengthening effect in Cu-1.2Ti-3TiSi{sub 2} powder particles and compacts was much greater. The binary and ternary powders both reveal properties superior to those of Cu-1.2Ti and Cu-1.2Ti-3TiSi{sub 2} compacts. Microhardness analysis as a function of the aging temperature of Cu-1.2Ti-3TiSi{sub 2} alloy shows an interaction between precipitation and dispersion hardening which offers possibilities for an application at elevated temperatures.

Bozic, D. [Institute of Nuclear Sciences 'Vinca', P.O.Box 522, 11001 Belgrade (Serbia); Dimcic, O. [TCF, Bulevar Mihajla Pupina 176, 11070 Belgrade (Serbia); Dimcic, B. [Institute of Nuclear Sciences 'Vinca', P.O.Box 522, 11001 Belgrade (Serbia)], E-mail: bidim@vin.bg.ac.yu; Cvijovic, I.; Rajkovic, V. [Institute of Nuclear Sciences 'Vinca', P.O.Box 522, 11001 Belgrade (Serbia)

2008-08-15

86

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

NASA Technical Reports Server (NTRS)

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

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

1992-01-01

87

Effect of fabrication parameters on the pore concentration of the aluminum metal foam, manufactured by powder metallurgy process  

Microsoft Academic Search

In this paper, the effect of fabrication parameters on the pore concentration of aluminum metal foam manufactured by powder\\u000a metallurgy process is studied. Aluminum metal foam specimens were fabricated from the mixture of aluminum powders (mean particle\\u000a size 60?m) and NaCl at 10,20,30,40(wt) % content under 200, 250, 300, MPa Pressures. All specimens were then sintered at\\u000a 630C for 2.5

Sermin Ozan; Seda Bilhan

2008-01-01

88

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

Microsoft Academic Search

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

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

2008-01-01

89

Wear behavior of a ferritic stainless steel with carbides manufactured through powder metallurgy  

NASA Astrophysics Data System (ADS)

A ferritic stainless steel has been manufactured through the powder metallurgy (P/M) route: uniaxial pressing and sintering. The sintering process was carried out in vacuum, at 1215 C for 30 min. After sintering, materials showed nearly 90% of density. A complete metallographic study was carried out using optical microscopy and scanning electron microscopy (SEM). Wear behavior was evaluated using a pin on disk test according to ASTM Standard G99. Eight test conditions were studied, varying the load (5 and 10 N), the speed (0.1 and 0.4 m/s), and the counter-material (chromium steel and a martensitic stainless steel). The sliding distance was 400 m, and tests were carried out on polished materials, with less than 30% of relative humidity. Moreover, wear tracks were observed by SEM in order to understand the wear processes involved, which depend mainly on the counter-material.

Ruiz-Navas, E. M.; Antn, N.; Gordo, E.; Navalpotro, R.; Velasco, F.

2001-08-01

90

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

91

Microstructure Evolution during Supersolvus Heat Treatment of a Powder Metallurgy Nickel-Base Superalloy  

NASA Astrophysics Data System (ADS)

Microstructure evolution during the supersolvus heat treatment of a powder-metallurgy, low-solvus, high-refractory (LSHR) superalloy was established. For this purpose, three lots of LSHR with varying initial carbon/boron composition and thermomechanical history were subjected to a series of short-time (induction) and long-time (furnace) heat treatments followed by scanning electron microscopy/electron backscatter diffraction and quantitative metallography. The size of the (pinned) gamma grains exhibited a limited dependence on heating rate and soak time at peak temperature, and it was generally smaller than the predictions based on the classic Smith-Zener model. The differences were rationalized in terms of stereological and pinning-particle location effects. Observations of limited coarsening of the carbide/boride pinning particles were interpreted in the context of prior experimental observations and a modified Lifshitz-Slyosov-Wagner model applied previously for the coarsening of compound phases in steels.

Semiatin, S. L.; McClary, K. E.; Rollett, A. D.; Roberts, C. G.; Payton, E. J.; Zhang, F.; Gabb, T. P.

2012-05-01

92

Accelerated Threshold Fatigue Crack Growth Effect-Powder Metallurgy Aluminum Alloy  

NASA Technical Reports Server (NTRS)

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

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

2002-01-01

93

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 m 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

94

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

DOEpatents

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

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

1993-01-01

95

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

96

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

SciTech Connect

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

Sean M. McDeavitt

2011-04-29

97

Effect of Coating Time on Corrosion Behavior of Electroless Nickel-Phosphorus Coated Powder Metallurgy Iron Specimens  

Microsoft Academic Search

Powder metallurgy iron specimens with porosities in the range 0% to 2% were electroless coated with nickel-phosphorus alloy from baths containing sodium hypophosphite (NaHPO·HO). The effect of coating time on thickness and phosphorus content of the deposit was analyzed. The free corrosion potentials and corrosion rates of the coated specimens were obtained by the Tafel extrapolation method in 1.0 M

D. Singh; R. Balasubramaniam; R. K. Dube

1995-01-01

98

Dry Sliding Wear of a Powder Metallurgy Copper-based Metal Matrix Composite Reinforced with Iron Aluminide Intermetallic Particles  

Microsoft Academic Search

In the present study, dry sliding wear behavior of a powder metallurgy copper alloy matrix composite containing iron aluminide (Fe3Al) intermetallic particles was investigated using a pin-on-disk machine. A sintered copper alloy (Cu90%, Sn10%) was used as matrix. Reinforcement Fe3Al particles were prepared by mechanical alloying (42 h) and used as reinforcement (10 and 20 vol%) in the matrix. The

K. Venkateswaran; M. Kamaraj; K. Prasad Rao

2007-01-01

99

MODELLING OF FRACTURE IN METAL POWDER COMPACTION PROCESS  

Microsoft Academic Search

Summary. This paper presents analysis on the prediction of crack initiation and propagation during the cold compaction process of metal powder. Based on the fracture criterion of granular material in compression, a displacement based finite element model with adaptive remeshing technique has been developed to analyse crack growth in iron powder compact. Friction between crack faces is modelled using the

A. K. Ariffin; S. M. Tahir

100

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

NASA Technical Reports Server (NTRS)

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

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

1987-01-01

101

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

NASA Technical Reports Server (NTRS)

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

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

2012-01-01

102

Factors Influencing Dwell Fatigue Cracking in Notches of Powder Metallurgy Superalloys  

NASA Technical Reports Server (NTRS)

The influences of heat treatment and cyclic dwells on the notch fatigue resistance of powder metallurgy disk superalloys were investigated for low solvus high refractory (LSHR) and ME3 disk alloys. Disks were processed to produce material conditions with varied microstructures and associated mechanical properties. Notched specimens were first subjected to baseline dwell fatigue cycles having a dwell at maximum load, as well as tensile, stress relaxation, creep rupture, and dwell fatigue crack growth tests at 704 C. Several material heat treatments displayed a bimodal distribution of fatigue life with the lives varying by two orders-of-magnitude, while others had more consistent fatigue lives. This response was compared to other mechanical properties, in search of correlations. The wide scatter in baseline dwell fatigue life was observed only for material conditions resistant to stress relaxation. For selected materials and conditions, additional tests were then performed with the dwells shifted in part or in total to minimum tensile load. The tests performed with dwells at minimum load exhibited lower fatigue lives than max dwell tests, and also exhibited early crack initiation and a substantial increase in the number of initiation sites. These results could be explained in part by modeling evolution of peak stresses in the notch with continued dwell fatigue cycling. Fatigue-environment interactions were determined to limit life for the fatigue cycles with dwells.

Gabb, T. P.; Telesman, J.; Ghosn, L.; Garg, A.; Gayda, J.

2011-01-01

103

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

104

Application of powder metallurgy techniques to produce improved bearing elements for liquid rocket engines  

NASA Technical Reports Server (NTRS)

The objective was to apply powder metallurgy techniques for the production of improved bearing elements, specifically balls and races, for advanced cryogenic turbopump bearings. The materials and fabrication techniques evaluated were judged on the basis of their ability to improve fatigue life, wear resistance, and corrosion resistance of Space Shuttle Main Engine (SSME) propellant bearings over the currently used 440C. An extensive list of candidate bearing alloys in five different categories was considered: tool/die steels, through hardened stainless steels, cobalt-base alloys, and gear steels. Testing of alloys for final consideration included hardness, rolling contact fatigue, cross cylinder wear, elevated temperature wear, room and cryogenic fracture toughness, stress corrosion cracking, and five-ball (rolling-sliding element) testing. Results of the program indicated two alloys that showed promise for improved bearing elements. These alloys were MRC-2001 and X-405. 57mm bearings were fabricated from the MRC-2001 alloy for further actual hardware rig testing by NASA-MSFC.

Moracz, D. J.; Shipley, R. J.; Moxson, V. S.; Killman, R. J.; Munson, H. E.

1992-01-01

105

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

106

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

NASA Technical Reports Server (NTRS)

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

Harf, F. H.

1985-01-01

107

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

NASA Technical Reports Server (NTRS)

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

Dellacorte, Christopher; Sliney, Harold E.

1989-01-01

108

Distribution of Inclusion-Initiated Fatigue Cracking in Powder Metallurgy Udimet 720 Characterized  

NASA Technical Reports Server (NTRS)

In the absence of extrinsic surface damage, the fatigue life of metals is often dictated by the distribution of intrinsic defects. In powder metallurgy (PM) alloys, relatively large defects occur rarely enough that a typical characterization with a limited number of small volume fatigue test specimens will not adequately sample inclusion-initiated damage. Counterintuitively, inclusion-initiated failure has a greater impact on the distribution in PM alloy fatigue lives because they tend to have fewer defects than their cast and wrought counterparts. Although the relative paucity of defects in PM alloys leads to higher mean fatigue lives, the distribution in observed lives tends to be broader. In order to study this important failure initiation mechanism without expending an inordinate number of specimens, a study was undertaken at the NASA Glenn Research Center where known populations of artificial inclusions (seeds) were introduced to production powder. Fatigue specimens were machined from forgings produced from the seeded powder. Considerable effort has been expended in characterizing the crack growth rate from inclusion-initiated cracks in seeded PM alloys. A rotating and translating positioning system, with associated software, was devised to map the surface inclusions in low-cycle fatigue (LCF) test bars and to monitor the crack growth from these inclusions. The preceding graph illustrates the measured extension in fatigue cracks from inclusions on a seeded LCF test bar subjected to cyclic loading at a strain range of 0.8 percent and a strain ratio (max/min) of zero. Notice that the observed inclusions fall into three categories: some do not propagate at all (arrest), some propagate with a decreasing crack growth rate, and a few propagate at increasing rates that can be modeled by fracture mechanics. The following graph shows the measured inclusion-initiated crack growth rates from 10 interrupted LCF tests plotted against stress intensities calculated for semi-elliptical cracks with the observed surface lengths. The expected scatter in the crack growth rates for stress intensity ranges near threshold is observed. These data will be used to help determine the distribution in growth rates of cracks emanating from inclusions as well as the proportion of cracks that arrest under various loading conditions.

Bonacuse, Peter J.; Kantzos, Pete T.; Barrie, Robert; Telesman, Jack; Ghosn, Louis J.; Gabb, Timothy P.

2004-01-01

109

Application of Optimization Technique in the Powder Compaction and Sintering Processes  

Microsoft Academic Search

9ABSTRACT In general, the shrinkage of the powder compact during the sintering process is not uniform due to the non-uniform density distribution of the powder compact during the compaction process. We have developed an optimization program for the powder compaction and sintering processes. The optimization program is composed of finite element analysis and optimization routines for powder compaction and sintering

Young-Sam Kwon; Suk-Hwan Chung; Chantal Binet; Rui Zhang; Renata S. Engel; Nicholas J. Salamon; Randall M. German

110

Applied mechanics modeling of granulated ceramic powder compaction  

SciTech Connect

In ceramic manufacturing processes such as dry-pressing, correlations between applied compacting pressure and resultant powder compact density are essential for defining reliable process conditions for ceramic components. Pressure-density diagrams have been developed as a tool for both process control and for understanding the compaction behavior of different powders. These types of diagrams, however, pertain only to the averag@ properties of a powder compact and do not address a significant issue in powder compaction processes: the formation of density gradients within the compact. Continuum-based mechanics models of varying complexity have addressed the influence of frictional forces acting at the powder-die wall interface which dissipate the applied pressure throughout the compact. Resulting pressure distribution models are then typically coupled with empirical functions relating pressure and density to obtain a green density distribution in the compact. All of these models predict similar trends; however, none predict the distribution with sufficient accuracy to be considered as a design tool for industrial applications.

Mahoney, F.M.; Readey, M.J.

1995-08-01

111

Influence of Thermal Aging on the Microstructure and Mechanical Behavior of Dual Phase Precipitation Hardened Powder Metallurgy Stainless Steels  

NASA Astrophysics Data System (ADS)

Increasing demand for high strength powder metallurgy (PM) steels has resulted in the development of dual phase PM steels. In this work, the effects of thermal aging on the microstructure and mechanical behavior of dual phase precipitation hardened powder metallurgy (PM) stainless steels of varying ferrite-martensite content were examined. Quantitative analyses of the inherent porosity and phase fractions were conducted on the steels and no significant differences were noted with respect to aging temperature. Tensile strength, yield strength, and elongation to fracture all increased with increasing aging temperature reaching maxima at 538C in most cases. Increased strength and decreased ductility were observed in steels of higher martensite content. Nanoindentation of the individual microconstituents was employed to obtain a fundamental understanding of the strengthening contributions. Both the ferrite and martensite hardness values increased with aging temperature and exhibited similar maxima to the bulk tensile properties. Due to the complex non-uniform stresses and strains associated with conventional nanoindentation, micropillar compression has become an attractive method to probe local mechanical behavior while limiting strain gradients and contributions from surrounding features. In this study, micropillars of ferrite and martensite were fabricated by focused ion beam (FIB) milling of dual phase precipitation hardened powder metallurgy (PM) stainless steels. Compression testing was conducted using a nanoindenter equipped with a flat punch indenter. The stress-strain curves of the individual microconstituents were calculated from the load-displacement curves less the extraneous displacements of the system. Using a rule of mixtures approach in conjunction with porosity corrections, the mechanical properties of ferrite and martensite were combined for comparison to tensile tests of the bulk material, and reasonable agreement was found for the ultimate tensile strength. Micropillar compression experiments of both as sintered and thermally aged material allowed for investigation of the effect of thermal aging.

Stewart, Jennifer

2011-12-01

112

Measurement of Electrical Conductivity of Porous Titanium and Ti6Al4V Prepared by the Powder Metallurgy Method  

NASA Astrophysics Data System (ADS)

Porous titanium and Ti6Al4V are produced by the powder metallurgy method. Dependence of the electrical conductivity on the porosity and pore size is investigated and the experimental results are correlative and compared with several earlier models. A newly modified Mori-Tanaka relationship based on the effective field method is proposed, which is successfully applied to describe the dependence of the electrical conductivity of porous titanium and Ti6Al4V on the porosity. The pore size has a minor effect on the electrical conductivity of both samples.

Zhu, Ke; Li, Cheng-Feng; Zhu, Zhen-Gang

2007-01-01

113

Effect of coating time on corrosion behavior of electroless nickel-phosphorus coated powder metallurgy iron specimens  

SciTech Connect

Powder metallurgy iron specimens with porosities in the range 0% to 2% were electroless coated with nickel-phosphorus alloy from baths containing sodium hypophosphite (NaH{sub 2}PO{sub 2}{center_dot}H{sub 2}O). The effect of coating time on thickness and phosphorus content of the deposit was analyzed. The free corrosion potentials and corrosion rates of the coated specimens were obtained by the Tafel extrapolation method in 1.0 M hydrochloric acid (HCl) solution. Corrosion rates of the coated specimens after heat treatment also were studied. The observed corrosion characteristics were explained by the mixed-potential theory.

Singh, D.; Balasubramaniam, R.; Dube, R.K. [Indian Inst. of Tech., Kanpur (India). Dept. of Materials and Metallurgical Engineering

1995-08-01

114

Wear behavior of AlCu and AlCu\\/SiC components produced by powder metallurgy  

Microsoft Academic Search

In the present study, the dry sliding wear behavior of some powder metallurgy (P\\/M) AlMgCu alloys with different weight\\u000a percentage of Cu (0, 1, 2, 3, 4, and 5wt%) and corresponding metal matrix composites reinforced with 5 or 10vol% silicon\\u000a carbide particles (SiC) have been carried using pin-on-disk apparatus. The tested specimens were tested against hardened steel\\u000a disk as a

Adel Mahamood Hassan; Ahmad Turki Mayyas; Abdalla Alrashdan; Mohammed T. Hayajneh

2008-01-01

115

Some aspects on plastic deformation of copper and coppertitanium carbide powder metallurgy composite preforms during cold upsetting  

Microsoft Academic Search

The densification, workability and strain hardening behaviour of sintered copper and Cu7.5%TiC powder metallurgy (P\\/M) composite\\u000a preforms during cold upsetting were investigated by the constitutive model using the experimental data. Cold upsetting of\\u000a copper and Cu7.5% TiC composite preforms having different aspect ratios were carried out and the formability behaviour of\\u000a the preforms under triaxial stress state was determined. The

R. Narayanasamy; V. Anandakrishnan; K. S. Pandey

2008-01-01

116

Study of alumina-trichite reinforcement of a nickel-based matric by means of powder metallurgy  

NASA Technical Reports Server (NTRS)

Research was conducted on reinforcing nickel based matrices with alumina trichites by using powder metallurgy. Alumina trichites previously coated with nickel are magnetically aligned. The felt obtained is then sintered under a light pressure at a temperature just below the melting point of nickel. The halogenated atmosphere technique makes it possible to incorporate a large number of additive elements such as chromium, titanium, zirconium, tantalum, niobium, aluminum, etc. It does not appear that going from laboratory scale to a semi-industrial scale in production would create any major problems.

Walder, A.; Hivert, A.

1982-01-01

117

Gamma prime precipitation modeling and strength responses in powder metallurgy superalloys  

NASA Astrophysics Data System (ADS)

Precipitation-hardened nickel-based superalloys have been widely used as high temperature structural materials in gas turbine engine applications for more than 50 years. Powder metallurgy (P/M) technology was introduced as an innovative manufacturing process to overcome severe segregation and poor workability of alloys with high alloying contents. The excellent mechanical properties of P/M superalloys also depend upon the characteristic microstructures, including grain size and size distribution of gamma' precipitates. Heat treatment is the most critical processing step that has ultimate influences on the microstructure, and hence, on the mechanical properties of the materials. The main objective of this research was to study the gamma ' precipitation kinetics in various cooling circumstances and also study the strength response to the cooling history in two model alloys, Rne88DT and U720LI. The research is summarized below: (1) An experimental method was developed to allow accurate simulation and control of any desired cooling profile. Two novel cooling methods were introduced: continuous cooling and interrupt cooling. Isothermal aging was also carried out. (2) The growth and coarsening kinetics of the cooling gamma' precipitates were experimentally studied under different cooling and aging conditions, and the empirical equations were established. It was found that the cooling gamma' precipitate versus the cooling rate follows a power law. The gamma' precipitate size versus aging time obeys the LSW cube law for coarsening. (3) The strengthening of the material responses to the cooling rate and the decreasing temperature during cooling was investigated in both alloys. The tensile strength increases with the cooling rate. In addition, the non-monotonic response of strength versus interrupt temperature is of great interest. (4) An energy-driven model integrated with the classic growth and coarsen theories was successfully embedded in a computer program developed to simulate the cooling gamma ' precipitation based on the first principle of thermodynamics. The combination of the thermodynamic and the kinetic approaches provided a more practical method to determine the critical nucleation energy. (5) The simulation results proved the gamma' burst theory and the existence of the multi-stage burst of gamma' precipitates, which shows good agreement with the experimental data in a variety of aspects.

Mao, Jian

118

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

119

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

120

Generation of powder compaction response diagrams  

SciTech Connect

The effect of elastic compliances in the testing system is shown to have a considerable influence on the compaction diagram generated via an automatic procedure. Proper accounting of this effect allows rapid and accurate diagrams to be made.

Matsumoto, R.L.K.

1986-10-01

121

Initial Assessment of the Effects of Nonmetallic Inclusions on Fatigue Life of Powder-Metallurgy-Processed Udimet(TM) 720  

NASA Technical Reports Server (NTRS)

The fatigue lives of modern powder metallurgy (PM) disk alloys are influenced by variabilities in alloy microstructure and mechanical properties. These properties can vary due to the different steps of materials/component processing and machining. One of these variables, the presence of nonmetallic inclusions, has been shown to significantly degrade low-cycle fatigue (LCF) life. Nonmetallic inclusions are inherent defects in powder alloys that are a by-product of powder-processing techniques. Contamination of the powder can occur in the melt, during powder atomization, or during any of the various handling processes through consolidation. In modern nickel disk powder processing facilities, the levels of inclusion contamination have been reduced to less than 1 part per million by weight. Despite the efforts of manufacturers to ensure the cleanliness of their powder production processes, the presence of inclusions remains a source of great concern for the designer. the objective of this study was to investigate the effects on fatigue life of these inclusions. Since natural inclusions occur so infrequently, elevated levels of inclusions were carefully introduced in a nickel-based disk superalloy, Udimet 720 (registered trademark of Special Metals Corporation), produced using PM processing. Multiple strain-controlled fatigue tests were then performed on this material at 650 C. Analyses were performed to compare the LCF lives and failure initiation sites as functions of inclusion content and fatigue conditions. A large majority of the failures in specimens with introduced inclusions occurred at cracks initiating from inclusions at the specimen surface. The inclusions could reduce fatigue life by up to 100 times. These effects were found to be dependent on strain range and strain ratio. Tests at lower strain ranges and higher strain ratios produced larger effects of inclusions on life.

Gabb, T. P.; Telesman, J.; Kantzos, P. T.; Bonacuse, P. J.; Barrie, R. L.

2002-01-01

122

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 1700C. 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.

123

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

SciTech Connect

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

Suzuki, Hiroyuki Y. [Graduate School of Engineering, Hiroshima University, 1-4-1 Kagamiayma, Higashi-Hiroshima, Hiroshima, 739-8527 (Japan)

2008-02-15

124

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

NASA Astrophysics Data System (ADS)

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

Suzuki, Hiroyuki Y.

2008-02-01

125

Compact Process for the Preparation of Microfine Spherical High-Niobium-Containing TiAl Alloy Powders  

NASA Astrophysics Data System (ADS)

High-Nb-containing TiAl alloys are a new generation of materials for high-temperature structural applications because of their superior high-temperature mechanical properties. The alloy powders can be widely used for additive manufacturing, thermal spraying, and powder metallurgy. Because of the difficulty of making microfine spherical alloy powders in quantity by conventional techniques, a compact method was proposed, which consisted of two-step ball milling of elemental powders and subsequent radio frequency (RF) argon plasma spheroidization. In comparison with conventional mechanical alloying techniques, the two-step milling process can be used to prepare alloy powders with uniform scale in a short milling time with no addition of process control agent. This makes the process effective and less contaminating. After RF argon plasma spheroidization, the powders produced exhibit good sphericity, and the number-average diameter is about 8.2 ?m with a symmetric unimodal particle size distribution. The powders perform high composition homogeneity and contain predominately supersaturated ? 2-Ti3Al phase. The oxygen and carbon contents of the spheroidized powder are 0.47% and 0.050%, respectively.

Tong, J. B.; Lu, X.; Liu, C. C.; Wang, L. N.; Qu, X. H.

2015-03-01

126

Compact Process for the Preparation of Microfine Spherical High-Niobium-Containing TiAl Alloy Powders  

NASA Astrophysics Data System (ADS)

High-Nb-containing TiAl alloys are a new generation of materials for high-temperature structural applications because of their superior high-temperature mechanical properties. The alloy powders can be widely used for additive manufacturing, thermal spraying, and powder metallurgy. Because of the difficulty of making microfine spherical alloy powders in quantity by conventional techniques, a compact method was proposed, which consisted of two-step ball milling of elemental powders and subsequent radio frequency (RF) argon plasma spheroidization. In comparison with conventional mechanical alloying techniques, the two-step milling process can be used to prepare alloy powders with uniform scale in a short milling time with no addition of process control agent. This makes the process effective and less contaminating. After RF argon plasma spheroidization, the powders produced exhibit good sphericity, and the number-average diameter is about 8.2 ?m with a symmetric unimodal particle size distribution. The powders perform high composition homogeneity and contain predominately supersaturated ? 2-Ti3Al phase. The oxygen and carbon contents of the spheroidized powder are 0.47% and 0.050%, respectively.

Tong, J. B.; Lu, X.; Liu, C. C.; Wang, L. N.; Qu, X. H.

2015-02-01

127

The role of new particle surfaces in synthesizing bulk nanostructured metallic materials by powder metallurgy  

Microsoft Academic Search

The role of new particle surfaces in synthesizing bulk nanostructured metallic materials by consolidation of nanostructured powders and nanopowders is analysed by developing three simple mathematical equations for calculating the ? factor for different thermomechanical powder consolidation processes such as hot pressing, high pressure torsion and extrusion. The ? factor is the fraction of the area of the powder particle

D. L. Zhang; C. C. Koch; R. O. Scattergood

2009-01-01

128

Powder compaction properties of sodium starch glycolate disintegrants.  

PubMed

The compaction behavior of three "as supplied" commercially available grades of sodium starch glycolate (SSG), Explotab, Primojel, and Vivastar P, was investigated at compression speeds of 0.17 and 30 mm/sec. The results suggested that the three "as supplied" materials exhibit different compression and compaction behavior. Primojel and Explotab exhibited similar compactibility, whereas Vivastar P produced compacts of poor integrity. This behavior was not mirrored in the compressibility of the powders, where Vivastar P and Explotab exhibited similar performance. The materials were studied using x-ray diffraction, scanning electron microscopy, Carr's compressibility index, and swelling volume. In terms of material characteristics, all the products exhibited similar swelling in water. Primojel and Explotab retained most of the crystallographic order from the parent potato starch and exhibited comparable particle surface topographies. Vivastar P contained the lowest moisture level. However, it is not clear if the poor compactibility of Vivastar P is due to differences in moisture content, the reduced surface topography, or subtle differences in the SSG polymer structures (substitution, cross-linking, and crystallinity). Overall, even though the three commercial grades of sodium starch glycolate are successfully used as disintegrants, they do exhibit differences in their "as supplied" powder mechanical properties: Primojel and Explotab exhibit similar compactibility, whereas Vivastar P is poorly compactable but exhibits similar compressibility to Explotab. These observations may have implications when formulating poorly compactable or moisture-sensitive drugs. PMID:12378967

Edge, S; Steele, D F; Staniforth, J N; Chen, A; Woodcock, P M

2002-09-01

129

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

NASA Technical Reports Server (NTRS)

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

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

1990-01-01

130

An Investigation of Microstructure and Phase Transformation Behavior of Cu40Zn-1.0 wt.% Ti Brass Via Powder Metallurgy  

NASA Astrophysics Data System (ADS)

The effects of Ti addition on phase transformation, precipitation behavior, and microhardness response of Cu40Zn brass were investigated at elevated heat treatment (HT) temperatures using the powder metallurgy method. The volume fraction of the ? phase increased with the elevated temperatures, which showed an equal value as that of the ? phase at 400 C, and reached a maximum value of 55.9% at 500 C. The solid solubility of Ti in Cu40Zn brass matrix decreased as the HT temperature increased. Supersaturated Ti showed high chemical potential for precipitates' reaction in Cu40Zn brass. Lower HT temperature retained higher Ti solid solubility and fine precipitates. The precipitates presented in form of Cu2TiZn intermetallic compound, distributing uniformly in brass matrix which suppressed the phase and grain growth. After HT at elevated temperature, the precipitates coalesced, grew coarser, and segregated at the primary particle boundaries. The microhardness of the BS40-1.0Ti compact was primarily not only dependent on the solid solubility of Ti, but also dependent on the phase volume fraction of the ? and ? phases.

Li, Shufeng; Imai, Hisashi; Atsumi, Haruhiko; Kondoh, Katsuyoshi

2013-10-01

131

Static and Dynamic Compaction of CL-20 Powders  

NASA Astrophysics Data System (ADS)

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

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

2009-12-01

132

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

133

Preparation of aluminium-fly ash particulate composite by powder metallurgy technique  

Microsoft Academic Search

Aluminium-fly ash mixtures containing different weight percentages of fly ash were prepared and compacted at pressures from\\u000a 138414 MPa. The compacts prepared at 414 MPa were sintered in nitrogen atmosphere at 600, 625 and 645C, respectively. The\\u000a time of sintering ranged from 0.56 h. The densification parameter and the green densities of the compacts were determined\\u000a as a function of

R. Q Guo; P. K Rohatgi; D Nath

1997-01-01

134

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

135

Static and Dynamic Compaction of CL-20 Powders  

NASA Astrophysics Data System (ADS)

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

Cooper, Marcia; Brundage, Aaron; Dudley, Evan

2009-06-01

136

Corrosion behaviour of aisi 304l and 316l stainless steels prepared by powder metallurgy in the presence of sulphuric and phosphoric acid  

Microsoft Academic Search

The corrosion rates of AISI 304L and 316L stainless steels prepared by powder metallurgy (P\\\\M) have been studied by continuous electrochemical methods, in different concentrations of inorganic acid solutions (sulphuric and phosphoric) at room temperature (T = 298 K). For comparison purposes, a simultaneous study was carried out on similar composition cast AISI 304L and AISI 316L stainless steels specially

E Otero; A Pardo; M. V Utrilla; E Senz; J. F lvarez

1998-01-01

137

The corrosion behaviour of AISI 304L AND 316L stainless steels prepared by powder metallurgy in the presence of organic acids  

Microsoft Academic Search

The corrosion rates of AISI 304L and 316L stainless steels prepared by powder metallurgy (P\\/M) have been studied by continuous current electrochemical methods, in organic acid solutions (acetic, formic, lactic and oxalic) at different concentrations. For comparison purposes a simultaneous study was carried out on cast AISI 304L and AISI 316L steels of similar composition. For this investigation polarization resistance

E. Otero; A. Pardo; M. V. Utrilla; F. J. Prez; C. Merino

1997-01-01

138

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

NASA Technical Reports Server (NTRS)

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

Calhoun, C. D.

1971-01-01

139

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

NASA Astrophysics Data System (ADS)

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

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

2015-02-01

140

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

SciTech Connect

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

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

1993-07-13

141

Microstructure and Strengthening Mechanisms in an Ultrafine Grained Al-Mg-Sc Alloy Produced by Powder Metallurgy  

NASA Astrophysics Data System (ADS)

Additions of Sc to an Al-Mg matrix were investigated, paying particular attention to the influence of Al3Sc precipitates and other dispersoids, as well as grain size, on mechanical behavior. Prior studies have shown that Sc significantly increases the strength of coarse-grained Al-Mg alloys. Prompted by these findings, we hypothesized that it would be of fundamental and technological interest to study the behavior of Sc additions to an ultrafine-grained (UFG) microstructure (e.g., 100's nm). Accordingly, we investigated the microstructural evolution and mechanical behavior of a cryomilled ultrafine grained Al-5Mg-0.4Sc (wt pct) and compared the results to those of an equivalent fine-grained material (FG) produced by powder metallurgy. Experimental materials were consolidated by hot isostatic pressing (HIP'ing) followed by extrusion or dual mode dynamic forging. Under identical processing conditions, UFG materials generate large Al3Sc precipitates with an average diameter of 154 nm and spaced approximately 1 to 3 ?m apart, while precipitates in the FG materials have a diameter of 24 nm and are spaced 50 to 200 nm apart. The strengthening mechanisms are calculated for all materials and it is determined that the greatest strengthening contributions for the UFG and FG materials are Mg-O/N dispersion strengthening and precipitate strengthening, respectively.

Harrell, Tammy J.; Topping, Troy D.; Wen, Haiming; Hu, Tao; Schoenung, Julie M.; Lavernia, Enrique J.

2014-09-01

142

Microstructure and Strengthening Mechanisms in an Ultrafine Grained Al-Mg-Sc Alloy Produced by Powder Metallurgy  

NASA Astrophysics Data System (ADS)

Additions of Sc to an Al-Mg matrix were investigated, paying particular attention to the influence of Al3Sc precipitates and other dispersoids, as well as grain size, on mechanical behavior. Prior studies have shown that Sc significantly increases the strength of coarse-grained Al-Mg alloys. Prompted by these findings, we hypothesized that it would be of fundamental and technological interest to study the behavior of Sc additions to an ultrafine-grained (UFG) microstructure ( e.g., 100's nm). Accordingly, we investigated the microstructural evolution and mechanical behavior of a cryomilled ultrafine grained Al-5Mg-0.4Sc (wt pct) and compared the results to those of an equivalent fine-grained material (FG) produced by powder metallurgy. Experimental materials were consolidated by hot isostatic pressing (HIP'ing) followed by extrusion or dual mode dynamic forging. Under identical processing conditions, UFG materials generate large Al3Sc precipitates with an average diameter of 154 nm and spaced approximately 1 to 3 ?m apart, while precipitates in the FG materials have a diameter of 24 nm and are spaced 50 to 200 nm apart. The strengthening mechanisms are calculated for all materials and it is determined that the greatest strengthening contributions for the UFG and FG materials are Mg-O/N dispersion strengthening and precipitate strengthening, respectively.

Harrell, Tammy J.; Topping, Troy D.; Wen, Haiming; Hu, Tao; Schoenung, Julie M.; Lavernia, Enrique J.

2014-12-01

143

Modeling the Constitutive Relationship of Powder Metallurgy Ti-47Al-2Nb-2Cr Alloy During Hot Deformation  

NASA Astrophysics Data System (ADS)

In the present work, the isothermal compression tests of PM alloy Ti-47Al-2Nb-2Cr were carried out in the temperature range of 950-1200 C. A Gleeble 1500D thermosimulation machine was used, and samples were tested at strain rates ranging from 10-3 to 10-1 s-1. Based on the obtained flow stress curves, the hot deformation behavior was presented. The constitutive relationship of powder metallurgy (PM) Ti-47Al-2Nb-2Cr alloy was developed using an Arrhenius-type constitutive model that involves strain compensation in addition to an artificial neural network model. The accuracy and reliability of the developed models were quantified in terms of statistical parameters such as correlation coefficient and absolute value of relative error. It was found that deformation temperature and strain rate have obvious effects on the flow characteristics, and the flow stress increases with the increasing strain rate and the decreasing temperature. Moreover, the proposed models possess excellent prediction capability of flow stresses for the present alloy during hot deformation. Compared with the traditional Arrhenius-type model, the backpropagation neural network model is more accurate when presenting the isothermal compressing deformation behavior at elevated temperatures for PM Ti-47Al-2Nb-2Cr alloy.

Sun, Yu; Hu, Lianxi; Ren, Junshuai

2015-01-01

144

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

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

145

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

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

146

An Investigation of High-Temperature Precipitation in Powder-Metallurgy, Gamma/Gamma-Prime Nickel-Base Superalloys  

NASA Astrophysics Data System (ADS)

The high-temperature-precipitation behavior of a typical powder-metallurgy, gamma-gamma-prime, nickel-base superalloy (LSHR) was determined and used to develop and validate a quantitative fast-acting model. To this end, a series of experiments comprising supersolvus solution treatment followed by continuous cooling at rates typical of those experienced during the manufacture of full-scale components was conducted for LSHR. The nucleation and growth of secondary-gamma-prime precipitates were deduced via metallography on samples water quenched at various temperatures during the cooling cycle. Further insight on nucleation and the extent of retained supersaturation during cooling was obtained from in situ synchrotron (X-ray diffraction) experiments involving cooling of LSHR samples at identical rates with or without a hold time at an intermediate temperature. The observations were interpreted using a fast-acting (spreadsheet) model which incorporated the important aspects of classical, homogeneous-nucleation theory and growth by bulk diffusion. In this regard, particular attention was paid to the determination of model input parameters such as the composition, free energy of formation, and surface energy of precipitates, and an effective diffusivity; the values so determined contrasted with those from existing thermodynamic and diffusion databases. It was demonstrated that fast-acting-model calculations based on a nickel-chromium pseudo-binary system gave good agreement with measurements of the evolution of precipitate volume fraction, number density, and size during continuous cooling.

Semiatin, S. L.; Kim, S.-L.; Zhang, F.; Tiley, J. S.

2015-04-01

147

An Investigation of High-Temperature Precipitation in Powder-Metallurgy, Gamma/Gamma-Prime Nickel-Base Superalloys  

NASA Astrophysics Data System (ADS)

The high-temperature-precipitation behavior of a typical powder-metallurgy, gamma-gamma-prime, nickel-base superalloy (LSHR) was determined and used to develop and validate a quantitative fast-acting model. To this end, a series of experiments comprising supersolvus solution treatment followed by continuous cooling at rates typical of those experienced during the manufacture of full-scale components was conducted for LSHR. The nucleation and growth of secondary-gamma-prime precipitates were deduced via metallography on samples water quenched at various temperatures during the cooling cycle. Further insight on nucleation and the extent of retained supersaturation during cooling was obtained from in situ synchrotron (X-ray diffraction) experiments involving cooling of LSHR samples at identical rates with or without a hold time at an intermediate temperature. The observations were interpreted using a fast-acting (spreadsheet) model which incorporated the important aspects of classical, homogeneous-nucleation theory and growth by bulk diffusion. In this regard, particular attention was paid to the determination of model input parameters such as the composition, free energy of formation, and surface energy of precipitates, and an effective diffusivity; the values so determined contrasted with those from existing thermodynamic and diffusion databases. It was demonstrated that fast-acting-model calculations based on a nickel-chromium pseudo-binary system gave good agreement with measurements of the evolution of precipitate volume fraction, number density, and size during continuous cooling.

Semiatin, S. L.; Kim, S.-L.; Zhang, F.; Tiley, J. S.

2015-01-01

148

Modeling the Constitutive Relationship of Powder Metallurgy Ti-47Al-2Nb-2Cr Alloy During Hot Deformation  

NASA Astrophysics Data System (ADS)

In the present work, the isothermal compression tests of PM alloy Ti-47Al-2Nb-2Cr were carried out in the temperature range of 950-1200 C. A Gleeble 1500D thermosimulation machine was used, and samples were tested at strain rates ranging from 10-3 to 10-1 s-1. Based on the obtained flow stress curves, the hot deformation behavior was presented. The constitutive relationship of powder metallurgy (PM) Ti-47Al-2Nb-2Cr alloy was developed using an Arrhenius-type constitutive model that involves strain compensation in addition to an artificial neural network model. The accuracy and reliability of the developed models were quantified in terms of statistical parameters such as correlation coefficient and absolute value of relative error. It was found that deformation temperature and strain rate have obvious effects on the flow characteristics, and the flow stress increases with the increasing strain rate and the decreasing temperature. Moreover, the proposed models possess excellent prediction capability of flow stresses for the present alloy during hot deformation. Compared with the traditional Arrhenius-type model, the backpropagation neural network model is more accurate when presenting the isothermal compressing deformation behavior at elevated temperatures for PM Ti-47Al-2Nb-2Cr alloy.

Sun, Yu; Hu, Lianxi; Ren, Junshuai

2015-03-01

149

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

NASA Technical Reports Server (NTRS)

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

Harf, F. H.

1982-01-01

150

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

151

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

152

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

153

Advanced powder metallurgy aluminum alloys via rapid solidification technology, phase 2  

NASA Technical Reports Server (NTRS)

Marko's rapid solidification technology was applied to processing high strength aluminum alloys. Four classes of alloys, namely, Al-Li based (class 1), 2124 type (class 2), high temperature Al-Fe-Mo (class 3), and PM X7091 type (class 4) alloy, were produced as melt-spun ribbons. The ribbons were pulverized, cold compacted, hot-degassed, and consolidated through single or double stage extrusion. The mechanical properties of all four classes of alloys were measured at room and elevated temperatures and their microstructures were investigated optically and through electron microscopy. The microstructure of class 1 Al-Li-Mg alloy was predominantly unrecrystallized due to Zr addition. Yield strengths to the order of 50 Ksi were obtained, but tensile elongation in most cases remained below 2 percent. The class 2 alloys were modified composition of 2124 aluminum alloy, through addition of 0.6 weight percent Zr and 1 weight percent Ni. Nickel addition gave rise to a fine dispersion of intermetallic particles resisting coarsening during elevated temperature exposure. The class 2 alloy showed good combination of tensile strength and ductility and retained high strength after 1000 hour exposure at 177 C. The class 3 Al-Fe-Mo alloy showed high strength and good ductility both at room and high temperatures. The yield and tensile strength of class 4 alloy exceeded those of the commercial 7075 aluminum alloy.

Ray, Ranjan; Jha, Sunil C.

1987-01-01

154

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

155

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

156

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

157

Influence of Thermal Aging on the Microstructure and Mechanical Behavior of Dual-Phase, Precipitation-Hardened, Powder Metallurgy Stainless Steels  

NASA Astrophysics Data System (ADS)

The effects of thermal aging on the microstructure and mechanical behavior of dual-phase, precipitation-hardened, powder metallurgy (PM) stainless steels of varying ferrite-martensite content were examined. Quantitative analyses of the inherent porosity and phase fractions were conducted on the steels, and no significant differences were noted with respect to aging temperature. Tensile strength, yield strength, and elongation to fracture all increased with increasing aging temperature reaching maxima at 811 K (538 C) in most cases. Increased strength and decreased ductility were observed in steels of higher martensite content. Nanoindentation of the individual microconstituents was employed to obtain a fundamental understanding of the strengthening contributions. Both the ferrite and martensite nanohardness values increased with aging temperature and exhibited similar maxima to the bulk tensile properties.

Stewart, J. L.; Williams, J. J.; Chawla, N.

2012-01-01

158

Liquid precursor infiltration processing of powder compacts. 2: Fracture toughness and strength  

Microsoft Academic Search

SiN powder compacts were infiltrated with liquid precursors which produce either Zr(Y)O (3 mol% YO) solid solution or amorphous SiN after pyrolysis at relative low temperatures and without shrinkage. Results show that cracks which occur within a thin, surface layer of the precursor during pyrolysis can extend into the powder compact. As suggested by theory, this cracking phenomenon could be

Wen-Chiang Tu; Fred F. Lange

1995-01-01

159

Investigation of magnetic properties, residual stress and densification in compacted iron powder specimens coated with polyepoxy  

Microsoft Academic Search

Soft magnetic powders are the main component of soft magnetic composites that are covered by an insulation layer. In this work, iron powder with high purity is covered by an inorganic material (iron phosphate) and then by a polyepoxy (DDS+DGEBA). The effect of amount of resin, different curing treatments and compaction pressure on the magnetic properties, residual stress, densification and

H. Shokrollahi; K. Janghorban; F. Mazaleyrat; M. Lo Bue; V. Ji; A. Tcharkhtchi

2009-01-01

160

Thermodynamic analysis of compact formation; compaction, unloading, and ejection. I. Design and development of a compaction calorimeter and mechanical and thermal energy determinations of powder compaction.  

PubMed

The aim of this investigation was to determine and evaluate the thermodynamic properties, i.e. heat, work, and internal energy change, of the compaction process by developing a 'Compaction Calorimeter'. Compaction of common excipients and acetaminophen was performed by a double-ended, constant-strain tableting waveform utilizing an instrumented 'Compaction Simulator.' A constant-strain waveform provides a specific quantity of applied compaction work. A calorimeter, built around the dies, used a metal oxide thermistor to measure the temperature of the system. A resolution of 0.0001 degrees C with a sampling time of 5 s was used to monitor the temperature. An aluminum die within a plastic insulating die, in conjunction with fiberglass punches, comprised the calorimeter. Mechanical (work) and thermal (heat) calibrations of the elastic punch deformation were performed. An energy correction method was outlined to account for system heat effects and mechanical work of the punches. Compaction simulator transducers measured upper and lower punch forces and displacements. Measurements of the effective heat capacity of the samples were performed utilizing an electrical resistance heater. Specific heat capacities of the samples were determined by differential scanning calorimetry. The calibration techniques were utilized to determine heat, work, and the change in internal energies of powder compaction. Future publications will address the thermodynamic evaluation of the tablet sub-processes of unloading and ejection. PMID:10722955

DeCrosta, M T; Schwartz, J B; Wigent, R J; Marshall, K

2000-03-30

161

M. Yu. Bal'shin and the Mechanics of Powder Material Compaction  

Microsoft Academic Search

The connection of Bal'shin consolidation theory with contemporary compaction mechanics is considered. The main principles of Bal'shin and proposals for powder compaction theory formulated by him are analyzed. A connection is established between the identity principle and the hypothesis of the existence of a representative element, and one possible way of determining its dimensions is demonstrated. The main attention is

Mikhail B. Shtern

2003-01-01

162

Strength and electrical conductivity of deformation-processed Cu-15 vol pct Fe alloys produced by powder metallurgy techniques  

SciTech Connect

Powder metallurgical techniques have been employed to prepare the precursor billets in the preparation of Cu-15 vol pct Fe alloys by deformation processing. It has been demonstrated that by (1) using high-purity gas-atomized Cu powders blended with commercial high-purity Fe powders and (2) controlling the time/temperature processing conditions within specific limits, it is possible to produce Cu-Fe deformation-processed alloys with strength/conductivity properties matching those of Cu-Nb, Cu-Ta, and Cu-Cr alloys. These properties are significantly superior to the best commercial alloys.

Jerman, G.A. (NASA, Marshall Space Flight Center, AL (United States)); Anderson, I.E.; Verhoeven, J.D. (Iowa State Univ., Ames (United States))

1993-01-01

163

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

164

Effect of Mass Fraction of Dolomite on the Foaming Behavior of AlSiCu Alloy Foam by Powder Metallurgy Route  

NASA Astrophysics Data System (ADS)

Metallic foams are commonly produced using hydride foaming agents. Carbonates are safer to handle than hydrides; furthermore, a fine and homogenous cell structure can be obtained by carbonates in the powder metallurgy route. In this study, the principle of foaming by dolomite, which is a carbonate, for AlSiCu alloy was investigated by observing foaming with a high-temperature transmission X-ray system and identifying the foaming gas with a gas chromatography-mass spectrometry technique. During foaming by dolomite, two stages of expansion were observed. The first stage of expansion was induced by the water vapor absorbed onto the AlSiCu powder surface, and the second stage of expansion was induced by the decomposition of dolomite. The coarse cells of the first stage of expansion were filled with H2, and the fine cells of the second stage of expansion were filled with CO. A fine and homogenous cell structure was achieved by controlling the mass fraction of dolomite with the fraction of adsorbed water, which induced cell coarsening.

Koizumi, Takuya; Kido, Kota; Kita, Kazuhiko; Mikado, Koichi; Gnyloskurenko, Svyatoslav; Nakamura, Takashi

2012-11-01

165

Strength and electrical conductivity of deformation processed Cu-15**v**/oFe metal matrix composites produced by powder metallurgy/techniques  

SciTech Connect

Copper based deformation processed metal matrix composites have been recently developed which exhibit high strengths with high electrical conductivities. The high strengthening is achieved through the establishment of second phase fibers in a Cu matrix. The most suitable second phase materials are BCC metals such as Nb, Cr, V, Ta, and Fe. The most economically attractive combination is the Cu-Fe system. Previous attempts at processing Cu-Fe composites have been hampered by the presence of Fe dissolved in the Cu matrix. Because of the large detriment dissolved Fe poses to the conductivity of the Cu matrix, cast processing the undeformed composites has led to low overall conductivity. To overcome this obstacle, powder metallurgy techniques have been adopted to consolidate blended elemental Cu and Fe powders. By controlling the time and temperature of the consolidation process, a Cu-15{sup v}/oFe metal matrix composite has been developed which matches the strength and conductivity properties of a similar cast Cu-15{sup v}/oNb alloy. The highest achievable strength was 1462 MPa with an attendant conductivity of 59 %IACS. 49 figs.

Jerman, G.A.

1991-05-30

166

FINITE ELEMENT ANALYSIS OF CAPPING MECHANISMS DURING PHARMACEUTICAL POWDER COMPACTION  

E-print Network

, and that cone capping is associated with intensive shear band formation during the decompression stage opening and deposits the powder into the die cavity under the influence of gravity [3-9]. During

de Gispert, Adri

167

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, Jrme

2013-07-15

168

Cold Compaction of Copper Powders Under Mechanical Vibration and Uniaxial Compression  

NASA Astrophysics Data System (ADS)

Physical experiments were carried out to study the cold compaction of copper powders under uniaxial compression using our self-designed equipment. Two kinds of copper powders with different particle sizes and distributions were considered. One-dimensional vibrations were utilized before compaction to systematically study the effect of parameters such as vibration frequency ?, amplitude A, and vibration intensity ? on the initial packing density. The macro-property and corresponding microstructures of compacts obtained from initial packings with and without vibrations were compared and analyzed. The results show that higher packing density can be obtained in the compaction of coarse powders with broad size distribution when other experimental conditions are fixed. For each powder, the evolution of packing density vs pressure takes on exponential correlation with high R 2 value. Much denser and more uniform compacts can be realized with the aid of vibration which can improve the particle rearrangement and result in the filling of macro pores formed in initial packing, and the characterization on the microstructure identifies that the particles inside the compact become polyhedrons with regular shape and uniformly distributed.

An, Xizhong; Xing, Zhitao; Jia, Chengchang

2014-04-01

169

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

NASA Technical Reports Server (NTRS)

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

Sankaran, K. K.

1987-01-01

170

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

171

Investigation into the compactability of metal powders during rolling  

Microsoft Academic Search

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

V. P. Katashinskii; G. A. Vinogradov

1965-01-01

172

Wear behaviour of organic asbestos based and bronze based powder metal brake linings  

Microsoft Academic Search

Bronze based brake linings, were produced by powder metallurgy technique and their wear behaviour was investigated and compared to that of asbestos ones. Bronze powders were compacted under 350, 500 and 600 MPa pressures and sintered at 810 C in ammonia atmosphere for 75 min. For the same friction distance, it was determined that temperature increase in the bronze based

Adem Kurt; Mustafa Boz

2005-01-01

173

Effect of ageing heat treatments on the microstructure and intergranular corrosion of powder metallurgy duplex stainless steels  

Microsoft Academic Search

The influence of ageing heat treatments (675 and 875C for 1.5 to 48h) on the microstructure and intergranular corrosion resistance of sintered in nitrogen duplex stainless steels was investigated. The materials were obtained by sintering mixtures of austenitic AISI 316L and ferritic AISI 430L powders. Corrosion behaviour was evaluated by using electrochemical techniques. The beneficial effect of nitrogen on corrosion

C. Garca; F. Martn; Y. Blanco; M. L. Aparicio

2010-01-01

174

Effects of tantalum addition on hysteresis losses and critical current densities of powder-metallurgy processed Nb{sub 3}Sn superconducting wires  

SciTech Connect

Powder-metallurgy processed (PMP) multifilamentary Nb{sub 3}Sn superconducting wires have been fabricated. The critical current densities and hysteresis losses of the wires are measured and the effects of tantalum addition to niobium on them are investigated. Although tantalum addition decreases both the critical current densities and the hysteresis losses, the reduction of the hysteresis loss is more pronounced. As a result, the effective filament diameter is diminished. The critical current density of the PMP Nb{sub 3}Sn wire may depend on the combination of the bridging among Nb{sub 3}Sn filaments and the supernormal interface pinning centers. This wire includes 3721 composite cores which consist of copper and Nb{sub 3}Sn. The non-homogeneous deformation of filaments is reduced by tantalum additions. Both the bridging among Nb{sub 3}Sn filaments and the super-normal interface pinning center energies may be reduced by tantalum additions, and therefore depressing the critical current density. Tantalum additions also depress the sausage-like deformation of composite cores, suggesting that both bridging and coupling among the composite cores is suppressed. Consequently both the hysteresis loss and the effective filament diameter are decreased.

Matsukura, N.; Fukumoto, Y.; Miyazaki, T. [Kobe Steel Ltd. (Japan)] [and others

1997-06-01

175

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 MPam1/2. 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

176

Ductilization of a powder metallurgy Al-17 wt pct Cu by means of channel-die compression and extrusion  

SciTech Connect

Metal powders always contain a surface oxide layer, which is particularly tenacious in aluminum alloys. After hot pressing, this oxide coats the particle boundaries and reduces the ductility. In this article, a study of the Al-17 wt pct Cu alloy densified from rapidly solidified powder is presented. Different thermomechanical treatments were investigated to improve the ductility of this material. Channel-die (CD) forging was performed at two temperatures (430 C and 500 C). Eight compression runs were applied to the samples in each CD treatment. At 430 C, three strain values per run were investigated (35, 50 and 70 pct). A bar was also extruded with a 40:1 ratio. Because of the small size of the samples, the ductility was assessed by means of the ring expansion test and analyzed by post mortem (fracture surface and cross section) observations. No ductility was measured after CD compression at 430 C, although it appears from the fracture surface observations that increasing the strain per tun has a beneficial effect. The CD compression at 500 C and extrusion were both successful at promoting ductility, extrusion being more effective.

Maire, E.; Wilkinson, D.S.; Embury, J.D. [McMaster Univ., Hamilton, ON (Canada). Dept. of Materials Science and Engineering; Henein, H. [Univ. of Alberta, Edmonton, AB (Canada). Advanced Materials and Processing Lab.

1998-10-01

177

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

178

The Influence of Sc and Zr Additions on the Microstructure and Mechanical Behavior of Ultrafine Grained Al-Mg Alloys Processed by Powder Metallurgy  

NASA Astrophysics Data System (ADS)

Additions of Sc and Zr to an Al-Mg matrix were investigated, paying particular attention to the influence of Al3Sc precipitates and other dispersoids, as well as grain size, on mechanical behavior. Prior studies have shown that Sc and Zr significantly increase the strength of coarse-grained Al-Mg alloys. Prompted by these findings, we hypothesized that it would be of fundamental and technological interest to study the behavior of Sc additions to an ultra-fine-grained (UFG) microstructure (e.g., 100's nm). Accordingly, we investigate the microstructural evolution and mechanical behavior of four powder metallurgy UFG Al-Mg-Sc-(Zr) compositions and compared the results to those of equivalent fine-grained (FG) compositions - Al-5Mg-0.1Sc, Al-3Mg-0.5Sc, Al-5Mg-0.4Sc and Al-5Mg-0.2Sc-0.2Zr (wt.%). Experimental materials were consolidated by hot isostatic pressing (HIP'ing) followed by extrusion or dual mode dynamic (DMD) forging. Under identical processing conditions, UFG ternary Al-5Mg-0.4Sc materials generate large Al3Sc precipitates with an average diameter of 154 nm and spaced approximately 1 - 3 ?m apart, while precipitates in the FG materials have an average diameter of 24 nm and are spaced 50 - 200 nm apart. The strengthening mechanisms are quantitatively evaluated for all materials and it is determined that the greatest strengthening contributions for the UFG and FG materials are dispersion strengthening due to the presence of Mg-rich oxides/nitrides and precipitate strengthening, respectively. Preliminary results suggest that replacing 0.2 wt% Sc with Zr results in higher strength, lower ductility and a change in precipitate distribution.

Harrell, Tammy Jeanne

179

?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

180

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

NASA Astrophysics Data System (ADS)

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

Tu, Wen J.

181

Decoupling of paramagnetic and ferrimagnetic AMS development during the experimental chemical compaction of illite shale powder  

NASA Astrophysics Data System (ADS)

Inclination shallowing of detrital remanent magnetization in sedimentary strata has solely been constrained for the mechanical processes associated with mud deposition and shallow compaction of clay-rich sediment, even though a significant part of mud diagenesis involves chemical compaction. Here we report, for the first time, on the laboratory simulation of magnetic assemblage development in a chemically compacting illite shale powder of natural origin. The experimental procedure comprised three compaction stages that, when combined, simulate the diagenesis and low-grade metamorphism of illite mud. First, the full extent of load-sensitive mechanical compaction is simulated by room temperature dry axial compression. Subsequently, temperature controlled chemical compaction is initiated by exposing the sample in two stages to amphibolite or granulite facies conditions (temperature is 490 to 750C and confining pressure is 170 or 300 MPa) both in the absence (confining pressure only) and presence of a deformation stress field (axial compression or confined torsion). Thermodynamic equilibrium in the last two compaction stages was not reached, but illite and mica dehydroxylation initiated, thus providing a wet environment. Magnetic properties were characterized by magnetic susceptibility and its anisotropy (AMS) in both high- and low-applied field. Acquisition of isothermal remanent magnetization (IRM), stepwise three-component thermal de-magnetization of IRM and first-order reversal curves were used to characterize the remanence-bearing minerals. During the chemical compaction experiments ferrimagnetic iron-sulphides formed after reduction of magnetite and detrital pyrite in a low sulphur fugacity environment. The degree of low-field AMS is unaffected by porosity reduction from 15 to 1 per cent, regardless of operating conditions and compaction history. High-field paramagnetic AMS increases with compaction for all employed stress regimes and conditions, and is attributed to illite transformation to iron-bearing mica. AMS of authigenic iron-sulphide minerals remained constant during compaction indicating an independence of ferrimagnetic fabric development to chemical compaction in illite shale powder. The decoupling of paramagnetic and ferrimagnetic AMS development during chemical compaction of pelite contrasts with findings from mechanical compaction studies.

Bruijn, Rolf H. C.; Almqvist, Bjarne S. G.; Hirt, Ann M.; Benson, Philip M.

2013-03-01

182

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

E-print Network

09 I, O THICKNESS DIAMETER Pigure 10. Effect of Particle Type of Various Powders on the Dimensionless Compaction Curve 30 3000 Jl GI I 2000 I- GI O 4I LEGEND ? 150 GRAM ? ? ? 100 GRAM 50 GRAM 1000 ~ . I 2 3 e 5 GTEARIC ACID Figure... 11. Relationship Between Level of Lubricant Added and Ejection Force of Atomized Copper Powder 31 5000 5000 LEGEND - ? 50 GRAM ? -100 GRAM l50 GRAM ILI O 4000 I- o III NI 2000 IDOD 0 I 2 3 4 5 STEARIC ACiD Figure 12. Relationship...

Sajdak, Richard James

1969-01-01

183

Study of Self Compacting Concrete Using Brick Dust and Marble Powder  

E-print Network

In recent years, Self Compacting Concrete (SCC) has gained a wide use for placement in congested reinforcement concrete structures where casting conditions are difficult and in high rise buildings where pump ability properties are required. For such applications the fresh concrete must possess high fluidity and good cohesiveness. The use of fine materials such as brick dust, marble powder and viscosity modifying agent can ensure the required concrete properties. In this experimental work attempt has been made to replace fine aggregate with brick dust and marble powder. Both brick kiln dust and marble powder are waste materials and are dumped as waste, causing land scarcity and environmental pollution. Using these types of waste material for concrete is a bigger step towards sustainable infrastructure development.

Er. Ranjodh Singh; Er. Rohin Kaushik; Er. Gurniwaz Singh

184

The effect of wall friction in the compaction of pharmaceutical tablets with curved faces: a validation study of the DruckerPrager Cap model  

Microsoft Academic Search

The compaction of porous materials can be modelled using micromechanical or phenomenological approaches. The micromechanical models are developed for either dense random packings or near fully dense ductile materials. Phenomenological models have been developed to describe the response of the material over a range of relative densities encountered in powder metallurgy, ceramics or composites industries. Pharmaceutical powders are particular in

I. C Sinka; J. C Cunningham; A Zavaliangos

2003-01-01

185

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

186

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

187

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

188

[Theoretical modeling and experimental research on direct compaction characteristics of multi-component pharmaceutical powders based on the Kawakita equation].  

PubMed

Base on the Kawakita powder compression equation, a general theoretical model for predicting the compression characteristics of multi-components pharmaceutical powders with different mass ratios was developed. The uniaxial flat-face compression tests of powder lactose, starch and microcrystalline cellulose were carried out, separately. Therefore, the Kawakita equation parameters of the powder materials were obtained. The uniaxial flat-face compression tests of the powder mixtures of lactose, starch, microcrystalline cellulose and sodium stearyl fumarate with five mass ratios were conducted, through which, the correlation between mixture density and loading pressure and the Kawakita equation curves were obtained. Finally, the theoretical prediction values were compared with experimental results. The analysis showed that the errors in predicting mixture densities were less than 5.0% and the errors of Kawakita vertical coordinate were within 4.6%, which indicated that the theoretical model could be used to predict the direct compaction characteristics of multi-component pharmaceutical powders. PMID:24974476

Si, Guo-Ning; Chen, Lan; Li, Bao-Guo

2014-04-01

189

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

190

Dry coating of micronized API powders for improved dissolution of directly compacted tablets with high drug loading.  

PubMed

Motivated by our recent study showing improved flow and dissolution rate of the active pharmaceutical ingredient (API) powders (20 ?m) produced via simultaneous micronization and surface modification through continuous fluid energy milling (FEM) process, the performance of blends and direct compacted tablets with high drug loading is examined. Performance of 50 ?m API powders dry coated without micronization is also considered for comparison. Blends of micronized, non-micronized, dry coated or uncoated API powders at 30, 60 and 70% drug loading, are examined. The results show that the blends containing dry coated API powders, even micronized ones, have excellent flowability and high bulk density compared to the blends containing uncoated API, which are required for direct compaction. As the drug loading increases, the difference between dry coated and uncoated blends is more pronounced, as seen in the proposed bulk density-FFC phase map. Dry coating led to improved tablet compactibility profiles, corresponding with the improvements in blend compressibility. The most significant advantage is in tablet dissolution where for all drug loadings, the t(80) for the tablets with dry coated APIs was well under 5 min, indicating that this approach can produce nearly instant release direct compacted tablets at high drug loadings. PMID:22921376

Han, Xi; Ghoroi, Chinmay; Dav, Rajesh

2013-02-14

191

Syntheses and Electrical Properties of Hexagonal Phase Group VI Metal Silicide Powders, Sintered Compacts and Bulk Crystals  

NASA Astrophysics Data System (ADS)

MoSi2 and WSi2 layers were grown on Mo and W substrates using the molten salt method. In addition, the Mo- and W-silicide compacts with the addition of Ti were also synthesized using Mo and W powders as the source materials, respectively, then the structural and electrical properties of the silicides were investigated. It was found that Si atoms penetrate into the compacts during the molten salt process. Moreover, nano-sized h-MoSi2 and h-WSi2 with the addition of Ti were formed in the compacts. The electrical conductivity of the compact comprised of Mo(Ti)Si2 showed almost no temperature dependence. On the other hand, for the compact comprised of W(Ti)Si2, the temperature dependence of the electrical conductivity showed a semiconducting property with an activation energy of about 0.18 eV.

Nonomura, T.; Wen, C.; Shirai, K.; Isobe, K.; Kato, A.; Kubota, Y.; Nakamura, T.; Hayakawa, Y.; Tatsuoka, H.

2011-05-01

192

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

193

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

194

Process Metallurgy Course Outline  

E-print Network

MATS4003 Process Metallurgy Advanced Course Outline Session 1, 2014 School of Materials Science Copper smelting 11-12 14 Technology design for light metals 12 Assignment due Week 12, Final exam #12 reactor design. Major technologies in ferrous and non-ferrous metallurgy and their development. Assessment

New South Wales, University of

195

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

E-print Network

-faced pharmaceutical compacts exposed to dissolution medium from one face of the tablet. The technique was demonstrated on three tableting excipients: hydroxypropylmethyl cellulose (HPMC), Eudragit RSPO, and lactose. Upon contact with water, HPMC initially shrinks...

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

2015-02-02

196

A homogenization approach to the yield strength of spherical powder compacts  

NASA Astrophysics Data System (ADS)

Optimal external estimates of the macroscopic strength criteria of a hexagonal array of identical spherical grains, under isostatic and closed die compaction, have been obtained through the use of the kinematic approach of the yield design homogenization method. Two appropriate unit cells, one for each stage compaction (I and II), and eight relevant failure mechanisms are considered. For comparison purposes, numerical simulations based on FEA similar to those of Ogbana and Fleck [1] have also been carried out. The shapes and sizes of the macroscopic yield surfaces are determined at various stages of compaction and it has been found in particular that they depend upon the loading history as well as the relative density of the compact.

Benabbes, A.; Siad, L.; Dormieux, L.; Liu, W. K.

2010-06-01

197

A homogenization approach to the yield strength of spherical powder compacts  

SciTech Connect

Optimal external estimates of the macroscopic strength criteria of a hexagonal array of identical spherical grains, under isostatic and closed die compaction, have been obtained through the use of the kinematic approach of the yield design homogenization method. Two appropriate unit cells, one for each stage compaction (I and II), and eight relevant failure mechanisms are considered. For comparison purposes, numerical simulations based on FEA similar to those of Ogbana and Fleck [1] have also been carried out. The shapes and sizes of the macroscopic yield surfaces are determined at various stages of compaction and it has been found in particular that they depend upon the loading history as well as the relative density of the compact.

Benabbes, A.; Siad, L. [URCA/GRESPI, Universite de Reims, UFR SEN, B.P. 1039, 51687 Reims cedex 2 (France); Dormieux, L. [LMSGC, Ponts ParisTech, cite Descartes, Champs-sur-Marne, F-77455 (France); Liu, W. K. [Northwestern University, DME, Evanston (United States) and SKKU (Korea, Republic of)

2010-06-15

198

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

199

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

200

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 0.110 GPa. This research work focused on unique piezochromism responses of the nanometer voids formed by the 520 nm inorganic ISOH nanometer powders. It was discovered that microstructures of the nanometer voids could change color at very low pressures of only 0.0020.01 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

201

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 600kg/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

202

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

203

Yield function for metal powder compaction based on micromechanics of particle deformation  

SciTech Connect

A new method based on the micromechanics of powder particle deformation for evaluating the yield function parameters is attempted. 2D particles in close packed arrangements with two different starting relative densities are considered. These unit cells are studied under plane strain conditions for basic densification response using Large Strain elasto-plastic Finite Element Analysis. Macroscopic values of stresses and the relative densities are recorded for different loading paths. Within the basic form of Shima`s yield function these material parameters are computed. The yield function parameters thus computed are found to be in good agreement with the experimental results reported on copper powder.

PavanaChand, C.; KrishnaKumar, R. [Indian Inst. of Tech., Madras (India)] [Indian Inst. of Tech., Madras (India)

1996-09-15

204

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

E-print Network

were heated either by plasma or by a resistive furnace technique. The plasma heating was performed Science B.V. Keywords: Supersolidus powder; AluminumÁ/bronze; Hollow cathode; Plasma heating 1 is very different from that of conventional heating (e.g., resistive, flame and induction). Knowledge

dos Santos, C.A.

205

Surface site density, silicic acid retention and transport properties of compacted magnetite powder  

NASA Astrophysics Data System (ADS)

In France, within the framework of investigations of the feasibility of deep geological disposal of high-level radioactive waste, studies on corrosion products of steel over packs are ongoing. Such studies concern silica and radionuclide retention. The objective of the present work is to study sorption of silicic acid on compacted magnetite in percolation cells to attempt to simulate confined site conditions. Potentiometric titration of commercial magnetite was carried out with both dispersed and compacted magnetite. The titration of the magnetite suspension has been made with two different methods: a batch method (several suspensions) and a direct fast method (one suspension). The Grans function gave 1.7 (0.4) and 2.4 (0.5) sorption sites nm -2 with these respective methods but site densities as high as 20/nm 2 could be obtained by modelling. The titration of magnetite compacted at 120 bars showed that the evolution of charge density on magnetite surfaces is similar for compacted and dispersed magnetite. Silicic acid sorption onto dispersed and compacted magnetite was similar with sorption site densities ranging between 2.2 and 4.4/nm 2.

Mayant, C.; Grambow, B.; Abdelouas, A.; Ribet, S.; Leclercq, S.

206

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

207

Integration approach of the Couette inverse problem of powder type self-compacting concrete in a wide-gap concentric cylinder rheometer  

Microsoft Academic Search

The influence of mineral additions and chemical admixtures on the shear thickening flow behaviour of powder type self-compacting concrete (SCC) is studied by means of a wide-gap concentric cylinder rheometer. The Couette inverse problem is treated by means of the integration method in order to derive the flow curve ?(??) from the torque measurements.According to the experimental results, the shear

G. Heirman; R. Hendrickx; L. Vandewalle; D. Van Gemert; D. Feys; G. De Schutter; B. Desmet; J. Vantomme

2009-01-01

208

Metallurgy Beyond Iron  

NASA Astrophysics Data System (ADS)

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

Gallino, Isabella; Busch, Ralf

2009-08-01

209

Microstructure and mechanical properties of Nb-Al-N and Nb-Si-B powder compacts produced by spark plasma sintering  

SciTech Connect

Nb-Al-N and Nb-Si-B powder compacts were prepared by spark plasma sintering, and their microstructure, mechanical properties and oxidation behavior were investigated. Adding nitrogen was easily done by blending or mechanically alloying Nb and AlN powders and then sintering them. The addition of nitrogen caused the formation of Nb{sub 2}N in all the Nb-Al-N compacts and Nb{sub 2}N and Nb{sub 3}Al{sub 2}N in compacts with high aluminum and nitrogen contents. The highest room-temperature hardness and the highest yield stress at 1,473K were observed for compacts consisting of Nb{sub 2}N and Nb{sub 3}Al{sub 2}N and those consisting of Nb{sub 2}N and Nb{sub 2}Al, respectively. Nb-Si-B compacts were prepared from elemental powders. Two or three of NbB{sub 2}, Nb{sub 5}Si{sub 3}, Nb{sub 5}Si{sub 3}B{sub 2} and NbSi{sub 2} phases were identified as constituent phases of Nb-Si-B compacts depending on composition unless a large amount of silicon is consumed by forming SiO{sub 2}. Contributions of NbB{sub 2}, Nb{sub 5}Si{sub 3} and Nb{sub 5}Si{sub 3}B{sub 2} phases to room-temperature hardness and yield stress at 1,973K were much larger than those of NbSi{sub 2}. However, the oxidation resistance of Nb-Si-B compacts increased with increasing the volume fraction of NbSi{sub 2}. The oxidation resistance of Nb{sub 5}Si{sub 3}B{sub 2} was better than that of Nb{sub 5}Si{sub 3}, but was not as good as that of NbSi{sub 2}.

Murakami, T.; Kitahara, A.; Kawahara, M.; Takahashi, Y.; Inui, H.; Yamaguchi, M.

1999-07-01

210

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

SciTech Connect

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

Mosley, W.C.

2001-09-17

211

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

212

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.

Novotn, K.; Sta?kov, A.; Hkknen, H.; Korppi-Tommola, J.; Otruba, V.; Kanick, V.

2007-12-01

213

APPLIED METALLURGY. KINETICS OF SINTERING IN fi-FeGe  

E-print Network

-Fe,Ge, by sinteringa compact mixture of powders of the basic elements, viz. iron and germanium. It was interesting magnetically ordered phases in the wide range of compositions. The structural and magnetic properties of /3-Fez appearing during the sintering of bFe5Ge3froma mixture of powders of thepure elements,Fe and Ge

Paris-Sud XI, Universit de

214

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 1350C) 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

215

Compressed iron powder core for electric motors  

Microsoft Academic Search

The magnetic properties of compressed powder cores made of iron powder with high compressibility were investigated with the goal of making them practical in electric motors. An electrolytic iron powder and an atomized iron powder with a finely powdered resin were compacted under a pressure of 6 tons\\/cm2. The influence of iron particle size on magnetic properties was more marked

K. Fukui; I. Watanabe; M. Morita

1972-01-01

216

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

217

The Rules of Ferrous Metallurgy  

PubMed Central

The ways in which the sciences have been delineated and categorized throughout history provide insights into the formation, stabilization, and establishment of scientific systems of knowledge. The Dresdener schools approach for explaining and categorizing the genesis of the engineering disciplines is still valid, but needs to be complemented by further-reaching methodological and theoretical reflections. Pierre Bourdieus theory of social practice is applied to the question of how individual agents succeed in influencing decisively a disciplines changing object orientation, institutionalisation and self-reproduction. Through the accumulation of social, cultural and economic capital, they succeed in realising their own organisational ideas and scientific programs. Key concepts for the analysis include the struggle for power and resources, monopolies of interpretation, and the degree of autonomy. A case study from the Aachener Technische Hochschule shows that the consolidation of ferrous metallurgy can be conceived as a symbolical struggle between Fritz Wst, professor for ferrous metallurgy, and the German Iron and Steel Institute, leading to a construction of a system of differences in which scientists accepted being scientists rather than entrepreneurs, and entrepreneurs accepted becoming entrepreneurs and renounced science.

2010-01-01

218

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.

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

2014-09-01

219

Aluminum base alloy powder metallurgy process and product  

NASA Technical Reports Server (NTRS)

A metallurgical method including cooling molten aluminum particles and consolidating resulting solidified particles into a multiparticle body, wherein the improvement comprises the provision of greater than 0.15% of a metal which diffuses in the aluminum solid state at a rate less than that of Mn. Aluminum containing greater than 0.15% of a metal which diffuses in the aluminum solid state at a rate less than that of Mn.

Paris, Henry G. (Inventor)

1986-01-01

220

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.

221

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

222

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

223

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

224

Improvements in microstructure homogenization and mechanical properties of diffusion-alloyed steel compact by the addition of Cr-containing powders  

Microsoft Academic Search

The use of diffusion-alloyed powders for fabricating powder metal parts, despite alleviating the segregation problem of the\\u000a alloying elements while retaining good compressibility, still cannot attain homogeneous microstructure in as-sintered products.\\u000a The presence of soft Ni-rich areas and pores causes poor mechanical properties compared to those of wrought steel counterparts.\\u000a This study investigated the effects of adding 0.5 wt pct

M. W. Wu; K. S. Hwang; H. S. Huang; K. S. Narasimhan

2006-01-01

225

DlcSsoo |LI Metallurgy Department  

E-print Network

1984 is included. INIS-descriptors; FUEL ELEMENTS, METALLURGY, NONDESTRUCTIVE TESTING, RESEARCH.11. High temperature oxygen-gas sensors 33 3.12. Non-destructive testing 34 4. FUEL ELEMENTS 36 4.1. U02~Zr of fatigue and creep, non-destructive testing, neu- tronradiography and ceramics. The joint work

226

Fabrication of metal matrix composite by semi-solid powder processing  

SciTech Connect

Various metal matrix composites (MMCs) are widely used in the automotive, aerospace and electrical industries due to their capability and flexibility in improving the mechanical, thermal and electrical properties of a component. However, current manufacturing technologies may suffer from insufficient process stability and reliability and inadequate economic efficiency and may not be able to satisfy the increasing demands placed on MMCs. Semi-solid powder processing (SPP), a technology that combines traditional powder metallurgy and semi-solid forming methods, has potential to produce MMCs with low cost and high efficiency. In this work, the analytical study and experimental investigation of SPP on the fabrication of MMCs were explored. An analytical model was developed to understand the deformation mechanism of the powder compact in the semi-solid state. The densification behavior of the Al6061 and SiC powder mixtures was investigated with different liquid fractions and SiC volume fractions. The limits of SPP were analyzed in terms of reinforcement phase loading and its impact on the composite microstructure. To explore adoption of new materials, carbon nanotube (CNT) was investigated as a reinforcing material in aluminum matrix using SPP. The process was successfully modeled for the mono-phase powder (Al6061) compaction and the density and density distribution were predicted. The deformation mechanism at low and high liquid fractions was discussed. In addition, the compaction behavior of the ceramic-metal powder mixture was understood, and the SiC loading limit was identified by parametric study. For the fabrication of CNT reinforced Al6061 composite, the mechanical alloying of Al6061-CNT powders was first investigated. A mathematical model was developed to predict the CNT length change during the mechanical alloying process. The effects of mechanical alloying time and processing temperature during SPP were studied on the mechanical, microstructural and compositional properties of the Al6061-CNT composites. A shear lag model was applied to predict the mechanical property (hardness) of the composite. This work demonstrated the promising potential of SPP in the fabrication of particle/fiber (nanotube) reinforced MMCs.

Wu, Yufeng [Ames Laboratory

2012-11-28

227

Characterization and Control of Powder Properties for Additive Manufacturing  

NASA Astrophysics Data System (ADS)

Powder characterization and handling in powder metallurgy are important issues and the required powder properties will vary between different component manufacturing processes. By understanding and controlling these, the final material properties for different applications can be improved and become more reliable. In this study, the metal powders used in additive manufacturing (AM) in terms of electron beam melting and selective laser melting have been investigated regarding particle size and shape using dynamic image analysis. In parallel, powder flow characteristics have been evaluated with a powder rheometer. Correlations within the results have been found between particle shape and powder flow characteristics that could explain certain effects of the powder processing in the AM processes. The impact, however, in the processing performance as well as in ultimate material properties was found to be limited.

Strondl, A.; Lyckfeldt, O.; Brodin, H.; Ackelid, U.

2015-03-01

228

Two-dimensional distribution of carbon nanotubes in copper flake powders  

Microsoft Academic Search

We report an approach of flake powder metallurgy to the uniform, two-dimensional (2D) distribution of carbon nanotubes (CNTs) in Cu flake powders. It consists of the preparation of Cu flakes by ball milling in an imidazoline derivative (IMD) aqueous solution, surface modification of Cu flakes with polyvinyl alcohol (PVA) hydrosol and adsorption of CNTs from a CNT aqueous suspension. During

Zhanqiu Tan; Zhiqiang Li; Genlian Fan; Wenhuan Li; Qinglei Liu; Wang Zhang; Di Zhang

2011-01-01

229

New Metallic Powders and Methods of Rolling Them  

Microsoft Academic Search

Powder metallurgy is gaining in importance, thanks to the possibilities it provides for creating new materials with unique combinations of properties and making semifinished products whose shape and dimensions are close to the shape and dimensions of the finished products. The interest in developing technologies for obtaining new materials has increased worldwide in recent years, especially in regard to the

N. P. Reutova; V. B. Akimenko; S. V. Pozharov

2001-01-01

230

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

Microsoft Academic Search

The ever growing industry of Powder Metallurgy (P\\/M) is developing to include new alloys and improve those currently available. This project relates to the optimization of a commercially available Al-Zn-Mg-Cu based alloy (Alumix 431D). This alloy is the P\\/M equivalent of the wrought 7075 alloy, and yields some of the top performance found in any available aluminum alloy. Optimization of

Michael Patrick Mosher

2009-01-01

231

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

232

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

233

THE PHYSICAL METALLURGY OF PRECIPITATION-HARDENABLE STAINLESS STEELS  

Microsoft Academic Search

The present knowledge on the physical metallurgy of precipitation-; hardenable stainless steels is presented. The alloys discussed include the ; martensitic types (Stainless W and 17-4 PH), the semiaustenitic types (177 PH, PH ; 15-7 Mo, AM 350, and AM 355), and the austenitic types (A-286 and HNM). The ; areas of metallurgy common to most or all of these

D. C. Ludwigson; A. M. Hall

1959-01-01

234

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

235

Microstructures of SiCp/MR64 composite prepared by detonation-gaseous spray deposition of mechanically alloyed powders  

SciTech Connect

The existence of amorphous structures will be reported for the first time in the deposited layer by detonation-gaseous spray deposition of mechanically alloyed SiCp/MR64 powders. MMCs are basically made in two ways: ingot metallurgy (IM) and powder metallurgy (PM). Some interesting results have been reported in preparing SiC particulate reinforced aluminium matrix composites by mechanical alloying. Obviously, using mechanically alloyed powders for preparation of MMCs greatly reduces the grain size of aluminium matrices and refines the SiC particles and disperses them within the aluminium powders. In previous PM techniques, hot extrusion was generally selected as the last forming step, but in doing so, the available characteristics of mechanically alloyed powders were lost. To retain the structural characteristics of MA powders rapid solidification techniques could be utilized. Thus, detonation-gaseous spray deposition (DGSD), previously used for surface spraying to obtain specific properties, is used to prepare SiCp/MR64 composites.

Che Chengwei; Yang Rang; Xie Zizhang; Zhao Qing (Univ. of Science and Technology, Beijing (China))

1994-07-01

236

Magnetic Properties of Iron Compacts in Relation to Sintering Temperature  

Microsoft Academic Search

Previous experiments have indicated that the magnetic permeability of sintered iron compacts is to a large extent determined by the final density of the compact. The permeability of five different iron powders has proved to be independent of the origin of the powder, if the compacts were sintered at the same temperature. The results were compared with the theory of

Robert Steinitz

1949-01-01

237

Development of a power metallurgy superalloy for use at 1800-2000 F (980-1090 C)  

NASA Technical Reports Server (NTRS)

A program was conducted to develop a powder metallurgy nickel-base superalloy for 1800-2000 F (980-1090 C) temperature applications. The feasibility of a unique concept for alloying carbon into a superalloy powder matrix and achieving both grain growth and a discrete particle grain boundary carbide precipitation was demonstrated. The process consisted of blending metastable carbides with a carbon free base alloy and consolidating this blend by hot extrusion. This was followed by heat treatment to grow a desired ASTM No. 2-3 grain size and to solution the metastable carbides to allow precipitation of discrete particle grain boundary carbides during subsequent aging heat treatments. The best alloy developed during this program was hydrogen-atomized, thermal-mechanically processed, modified MAR-M246 base alloy plus VC (0.28 w/o C). Although below those for cast MAR-M246, the mechanical properties exhibited by this alloy represent the best combination offered by conventional powder metallurgy processing to date.

Kortovich, C. S.

1973-01-01

238

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

239

Effect of the parameters of dynamic hot pressing on the structure and properties of the powder material ZhGrO, 8D2N3G3CaF 2 14 I. Initial porosity, work of compaction, sintering temperature and time, technological gap  

Microsoft Academic Search

The powdered antifriction iron base material ZhGrO,SD2N3G3CaF214 [I] is obtained from a multicomponent charge with the following composition, (wt.) %: 0.8 C; 2 Cu; 3 Mn; 3 Ni; 14 CaF2, the remainder Fe, by the method of dynamic hot pressing (DHP) of porous compacts. In the present work we investigate the effect of the parameters of DHP on the structure

Yu. G. Dorofeev; G. Sh. Musalov; A. T. Mamedov

1990-01-01

240

Powder Particulars  

NSDL National Science Digital Library

In this introductory activity and demonstration, learners are introduced to the concept that different substances react chemically in characteristic ways. First learners compare the way baking soda and baking powder react with vinegar. Then they see dramatic color changes when red cabbage indicator is added to cream of tartar and laundry detergent. From this, learners are ready to identify unknown powders based on their reactive properties.

2012-04-08

241

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

242

Electrically conductive ceramic powders  

NASA Astrophysics Data System (ADS)

Electrically conductive ceramic powders were investigated in this project. There are three ways to produce those materials. The first is doping alkali metal into the titanium dioxides in an inert or reducing atmosphere. The second is reducing un-doped titanium dioxide, forming a non-stoichiometric composition in a hydrogen atmosphere. The third is to coat a conductive layer, reduced titanium dioxide, on an insulating core such as alumina. Highly conductive powders have been produced by all these processes. The conductivity of powder compacts ranged between 10-2 and 10 S/cm. A novel doping process was developed. All samples were doped by a solid-vapor reaction instead of a solid state reaction. Titanium dioxide was doped with alkali metals such as Na or Li in this study. The alkali metal atom contributes an electron to the host material (TiO2), which then creates Ti 3+ ion. The conductivity was enhanced by creating the donor level due to the presence of these Ti3+ ions. The conductivity of those alkali doped titanium oxides was dependent on the doping level and charge mobility. Non-stoichiometric titanium oxides were produced by reduction of titanium dioxide in a hydrogen atmosphere at 800C to 1000C for 2 to 6 hours. The reduced titanium oxides showed better stability with respect to conductivity at ambient condition when compared with the Na or Li doped samples. Conductive coatings were prepared by coating titanium precursors on insulating core materials like SiO2, Al2O3 or mica. The titania coating was made by hydrolysis of titanyl sulfate (TiOSO 4) followed by a reduction procedure to form reduced titanium oxide. The reduced titanium oxides are highly conductive. A uniform coating of titanium oxides on alumina cores was successfully produced. The conductivity of coated powder composites was a function of coating quantity and hydrolysis reaction temperature. The conductivity of the powder as a function of structure, composition, temperature, frequency and moisture was studied. Three classifications of structure were identified for alkali-doped titanium oxides: (1) Pure titanium dioxide phase with alkali ions located in interstitial positions. (2) The titanium bronze phases. (3) Alkali-doped titanium oxides. Highly conductive powders were obtained in the first and second classifications with conductivity of 10-2 to 10 S/cm. Materials in the third classification had poor conductivity below 10-3 S/cm. The conductivity of a powder was determined mainly by the grain conductivity and the grain contact conductivity. The present results of impedance spectroscopy suggested that the grain contact resistance was a major factor of the electrical resistance of the samples. The aging effect at different moisture conditions was also caused by an increase of the contact resistance. Both sodium-doped and reduced titanium oxides showed re-oxidation at elevated temperature (above 140C) in air, which is most probably caused by oxidizing the Ti3+ ions under those conditions. Lithium doped titanium oxides did not show this re-oxidation at temperatures up to 200C. Theoretical models were applied to describe the effects of porosity, contact configuration and grain surface on conductivity of powder compacts. Percolation theory was used in the present study to demonstrate the effect of mixtures of conductive and non-conductive powders, which is one of applications for conductive ceramic powders when they are used as filler materials in paper, paints or plastics.

Lu, Yanxia

1999-11-01

243

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

NASA Astrophysics Data System (ADS)

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

Mosher, Michael Patrick

244

Accretion of titanium carbide by electrical discharge machining with powder suspended in working fluid  

Microsoft Academic Search

A surface modification method by electrical discharge machining (EDM) with a green compact electrode has been studied to make thick TiC or WC layer. Titanium alloy powder or tungsten powder is supplied from the green compact electrode and adheres on a workpiece by the heat caused by discharge. To avoid the production process of the green compact electrode, a surface

Katsushi Furutania; Akinori Saneto; Hideki Takezawa; Naotake Mohri; Hidetaka Miyake

2001-01-01

245

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

Federal Register 2010, 2011, 2012, 2013, 2014

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

2013-02-05

246

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 analytical chemistry and metallurgy. In 1952, the first LANL CMR facility was completed. At that time chemistry and metallurgy. Upgrades to the original CMR were completed in 2002. In 2012, the CMR facility

247

A laboratory means to produce tough aluminum sheet from powder  

NASA Technical Reports Server (NTRS)

The rapid solidification of aluminum alloys as powder and the subsequent fabrication processes can be used to develop and tailor alloys to satisfy specific aerospace design requirements, including high strength and toughness. Laboratory procedures to produce aluminum powder-metallurgy (PM) materials are efficient but require evidence that the laboratory methods used can produce a product with superior properties. This paper describes laboratory equipment and procedures which can be used to produce tough aluminum PM sheet. The processing of a 2124 + 0.9 percent Zr aluminum alloy powder is used as an example. The fully hardened sheet product is evaluated in terms of properties and microstructure. The key features of the vacuum hot press pressing operation used to consolidate the powder are described. The 2124 + 0.9 percent Zr - T8 temper aluminum sheet produced was both strong (460-490 MPa yield strength) and tough (Kahn Tear unit-propagation- energy values over three times those typical for ingot metallurgy 2024-T81). Both the longitudinal and longitudinal-transverse directions of the sheet were tested. The microstructure was well refined with subgrains of one or two micrometers. Fine dispersoids of Al3Zr in the precipitate free regions adjacent to boundaries are believed to contribute to the improved toughness.

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

1990-01-01

248

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

249

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

250

PETROLEUM SOCIETY CANADIAN INSTITUTE OF MINING, METALLURGY & PETROLEUM  

E-print Network

1 PETROLEUM SOCIETY CANADIAN INSTITUTE OF MINING, METALLURGY & PETROLEUM PAPER 2002-074 Temperature Canada Ltd. 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

Schramm, Laurier L.

251

Contribution to mechanical metallurgy behaviour of steel during continuous casting  

Microsoft Academic Search

The paper is devoted to the study of the mechanical metallurgy characteristics of the mushy zone. The basic parameters of the brittle temperature range (TB), the zero strength (ZST), the zero ductility temperature (ZDT) and the liquid impenetrable temperature (LIT) are used for explaining the possibility of cracking. This temperature range was defined in the following form: ZDT

Z Jonta; A Hernas; K Mazanec

1998-01-01

252

Materials and Metallurgy Materials Science and Metallurgical Engineering  

E-print Network

Materials and Metallurgy Materials Science and Metallurgical Engineering Objective Students will learn about raw materials and where they come from. Standards and Objectives · 7th Grade Standard 1, Objective 3 · Chemistry Standard 4, Objective 1 Learning Outcomes Students will learn: · Where raw materials

Provancher, William

253

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

254

Characterization of reinforcement distribution in Al\\/(Al 2O 3) p composites obtained from composite powder  

Microsoft Academic Search

A composite powder Al(Al2O3)p obtained in a rotary-vibration mill was used as a semifinished component to manufacture particle-reinforced metal matrix composites (PRMMCs) using cast and powder metallurgy technologies. For a quantitative description of the inhomogeneity of Al2O3 particle distributions in the aluminum matrix the following methods were applied: nearest neighbor distance, radial distribution function, influence zone morphology, systematic scanning and

Anita Olszwka-Myalska; Janusz Szala; Jan Cwajna

2001-01-01

255

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

256

Investigation of typical properties of nanocrystalline iron powders prepared by ball milling techniques  

NASA Astrophysics Data System (ADS)

Metallic powder has applications in many fields. In applications for preservation and anti-oxidation, iron powder has been used as an air oxygen reducer which is capable of decreasing microclimatic oxygen concentrations in a hermetic mini-environment. In this role, if we increase the specific surface area by reducing the particle size of the iron powder, the rate and performance of oxygen reduction will be improved significantly. In addition, the porosity of iron powder also contributes considerably. The iron powder can be fabricated using many methods: chemical deposition, powder metallurgy and mechanical milling. The technique of milling has certain advantages, especially for the formation of technical iron powder. The experimental equipment used was a Fritsch P-6 planetary ball mill. The iron powder was prepared with different milling times, from 1 up to 30 h in acetone as a protective environment. The powder products obtained were analyzed using field emission scanning electron microscope (FE-SEM), energy dispersive x-ray (EDX), x-ray diffraction (XRD), dynamic laser scattering (DLS), BrunauerEmmettTeller (BET) techniques and also magnetic characterization by vibrating sample magnetometer (VSM). The results show a correlation between the milling time and the crystallite and particle size, specific surface area, magnetic properties and nanoscale porosity of the iron powder. The iron powders obtained were a kind of mesoporous materials. The properties of the iron powder were examined with respect to their oxygen reducing kinetics.

Trinh Bui, Tien; Le, Xuan Que; Phuong To, Duy; Tich Nguyen, Van

2013-12-01

257

Metals for bone implants. Part 1. Powder metallurgy and implant rendering.  

PubMed

New metal alloys and metal fabrication strategies are likely to benefit future skeletal implant strategies. These metals and fabrication strategies were looked at from the point of view of standard-of-care implants for the mandible. These implants are used as part of the treatment for segmental resection due to oropharyngeal cancer, injury or correction of deformity due to pathology or congenital defect. The focus of this two-part review is the issues associated with the failure of existing mandibular implants that are due to mismatched material properties. Potential directions for future research are also studied. To mitigate these issues, the use of low-stiffness metallic alloys has been highlighted. To this end, the development, processing and biocompatibility of superelastic NiTi as well as resorbable magnesium-based alloys are discussed. Additionally, engineered porosity is reviewed as it can be an effective way of matching the stiffness of an implant with the surrounding tissue. These porosities and the overall geometry of the implant can be optimized for strain transduction and with a tailored stiffness profile. Rendering patient-specific, site-specific, morphology-specific and function-specific implants can now be achieved using these and other metals with bone-like material properties by additive manufacturing. The biocompatibility of implants prepared from superelastic and resorbable alloys is also reviewed. PMID:24956564

Andani, Mohsen Taheri; Shayesteh Moghaddam, Narges; Haberland, Christoph; Dean, David; Miller, Michael J; Elahinia, Mohammad

2014-10-01

258

Effect of the Machining Processes on Low Cycle Fatigue Behavior of a Powder Metallurgy Disk  

NASA Technical Reports Server (NTRS)

A study has been performed to investigate the effect of various machining processes on fatigue life of configured low cycle fatigue specimens machined out of a NASA developed LSHR P/M nickel based disk alloy. Two types of configured specimen geometries were employed in the study. To evaluate a broach machining processes a double notch geometry was used with both notches machined using broach tooling. EDM machined notched specimens of the same configuration were tested for comparison purposes. Honing finishing process was evaluated by using a center hole specimen geometry. Comparison testing was again done using EDM machined specimens of the same geometry. The effect of these machining processes on the resulting surface roughness, residual stress distribution and microstructural damage were characterized and used in attempt to explain the low cycle fatigue results.

Telesman, J.; Kantzos, P.; Gabb, T. P.; Ghosn, L. J.

2010-01-01

259

SiC particle cracking in powder metallurgy processed aluminum matrix composite materials  

Microsoft Academic Search

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

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

1995-01-01

260

Porous titanium scaffolds fabricated using a rapid prototyping and powder metallurgy technique  

Microsoft Academic Search

One of the main issues in orthopaedic implant design is the fabrication of scaffolds that closely mimic the biomechanical properties of the surrounding bone. This research reports on a multi-stage rapid prototyping technique that was successfully developed to produce porous titanium scaffolds with fully interconnected pore networks and reproducible porosity and pore size. The scaffolds' porous characteristics were governed by

Garrett E. Ryan; Abhay S. Pandit; Dimitrios P. Apatsidis

2008-01-01

261

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

262

Technological Advancement in Electrical Discharge Machining with Powder Metallurgy Processed Electrodes: A Review  

Microsoft Academic Search

Electrical discharge machining (EDM) is a well-established machining option for processing hard materials with complex geometrical shapes which are extremely difficult-to-machine by conventional machining processes. These hard materials find applications where lower surface cracks, wear resistance, corrosion resistance, etc. are desirable surface properties. In recent years, research has been carried out to determine the possibility of employing electrode as feed

Naveen Beri; Sachin Maheshwari; Chitra Sharma; Anil Kumar

2010-01-01

263

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

NASA Technical Reports Server (NTRS)

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

Chellman, D. J.

1984-01-01

264

Development of powder metallurgy Al alloys for high temperature aircraft structural applications, phase 2  

NASA Technical Reports Server (NTRS)

In this continuing study, the development of mechanically alloyed heat resistant aluminum alloys for aircraft were studied to develop higher strength targets and higher service temperatures. The use of higher alloy additions to MA Al-Fe-Co alloys, employment of prealloyed starting materials, and higher extrusion temperatures were investigated. While the MA Al-Fe-Co alloys exhibited good retention of strength and ductility properties at elevated temperatures and excellent stability of properties after 1000 hour exposure at elevated temperatures, a sensitivity of this system to low extrusion strain rates adversely affected the level of strength achieved. MA alloys in the Al-Li family showed excellent notched toughness and property stability after long time exposures at elevated temperatures. A loss of Li during processing and the higher extrusion temperature 482 K (900 F) resulted in low mechanical strengths. Subsequent hot and cold working of the MA Al-Li had only a mild influence on properties.

Chellman, D. J.

1982-01-01

265

Aging of powder metallurgy N14K7M5T2 maraging steel  

SciTech Connect

The authors study the aging process of sintered N14K7M5T2 marging steel at temperatures of 460-590 C with an isothermal hold of 40 min to 10 h. Electron microscopy was used. The purpose of the investigations was establishment of the type of precipitated phases and their size, form, and kinetics of growth in relation to the aging cycles. An analysis of the electrondiffraction patterns of specimens aged under different conditions made it possible to identify Ni/sub 3/ Ti as the hardening phase.

Antsiferov, V.N.; Grevnov, L.M.; Maslenikov, N.N.

1985-04-01

266

Developments of a powder-metallurgy, MZC copper-alloy, water-cooled gas turbine component  

Microsoft Academic Search

The Department of Energy of the Federal Government has sponsored a technology development and verification testing program.\\u000a This work is in support of an advanced, watercooled gas turbine firing at 2600 F (1427 C). As part of this turbine, strong\\u000a emphasis has been placed on the design and testing of a composite firststage nozzle. One of the materials making up

L. G. Peterson

1984-01-01

267

Weldability of a rapid solidification/powder metallurgy Al-8Fe-2Mo alloy  

SciTech Connect

The investigation utilized EB and Nd:YAG pulsed laser welding processes to produce autogenous, full-penetration welds with a high depth-to-width ratio FZ and minimal HAZ; characterized weld microstructure using light microscopy, SEM and TEM; evaluated weld mechanical properties; established interrelationships between weld microstructure, mechanical properties and fracture characteristics, and determined FZ solidification behavior. The results revealed significant microstructure variations across EB and pulsed Nd:YAG laser weld FZ. High FZ cooling rates ({approx equal}10{sup 3} C/s) generated an extremely fine FZ structure which exhibited a hardness comparable with base metal. However, occurrence of a coarse-grained FBR in these welds formed a weak-link with base metal, promoted preferential failure with low ductility and minimum weld joint efficiency (73%). Utilization of lower EB weld energy inputs and higher FZ cooling rates ({approx equal}10{sup 5} C/s) eliminated the coarse FBR and promoted failure in HAZ with acceptable ductility and high joint efficiency (88%). Nd:YAG pulsed laser welding provided a higher energy density and rapid FZ cooling rate ({approx equal}10{sup 6} C/s), produced submircon-sized spherical intermetallic particles in a fine-grained columnar-dendritic alpha aluminum matrix, and promoted preferential failure in the unaffected base metal indicating 100% joint efficiency. Solidification analysis related the occurrence of specific FZ microstructures to the presence of unmelted/undissolved base metal dispersoid particles and local thermal conditions. At relatively shallow temperature gradients and low FZ cooling rates, these particles produced coarse-grained FZ microstructures. In contrast, rapid FZ cooling rate limited the growth of the particles.

Krishnaswamy, S.

1989-01-01

268

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

NASA Technical Reports Server (NTRS)

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

Chern, T. S.

1985-01-01

269

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 1350C) 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

270

Gallium arsenide recycle chemistry and metallurgy  

SciTech Connect

Research was successfully conducted on a smelting approach to separate gallium from arsenic using a liquid copper alloy to collect arsenic while oxidizing the gallium into a soda-silica slag. The slag and copper form two immiscible liquid phases. With GaAs in powder form, smelting at 1150 to 1220{degree}C yields 98% of the gallium in the slag and at least 96% of the arsenic in the copper. The gallium concentration in this slag is, relative to other sources, very high, and it can be processed further to obtain crude gallium. The effect of chemical oxidizers on arsenic and gallium distribution between slag and copper was determined. The solidified copper-arsenic alloy is environmentally inert. However, any precious metals present with the electronic scrap will nearly completely collect in the copper. Commercial copper refineries are capable of recovering precious metals from the copper-arsenic alloy, and are equipped to handle large amounts of arsenic when compared with the amount of arsenic used in GaAs devices, even with many fold future expansions.

Bartlett, R.W.

1987-03-23

271

Ceramic compaction models: Useful design tools or simple trend indicators?  

SciTech Connect

It is well-known that dry pressing of ceramic powders leads to density gradients in a ceramic compact resulting in non-uniform shrinkage during densification. This necessitates diamond grinding to final dimensions which, in addition to being an extra processing step, greatly increases the manufacturing cost of ceramic components. To develop methods to control and thus mitigate density variations in compacted powders, it has been an objective of researchers to better understand the mechanics of the compaction process and the underlying material and tooling effects on the formation of density gradients. This paper presents a review of models existing in the literature related to the compaction behavior of ceramic powders. In particular, this paper focuses on several well-known compaction models that predict pressure and density variations in powder compacts.

Mahoney, F.M.; Readey, M.J.

1995-08-01

272

Sintering and Mechanical Properties of AISI M2 High-Speed Steel Powder Molded at Low Pressures  

Microsoft Academic Search

Low compaction pressures of powders result in low die wear, less power consumption and high production rate. The present study aims to investigate compaction, vacuum sintering, and mechanical behavior of AISI M2 high speed steel (HSS) powder cold molded at relatively low pressures (98392Mpa). It was found that sintered density rised with compaction pressure, time, and temperature. Full density was

S. Eroglu

2010-01-01

273

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

274

Synthesis and processing of nanocrystalline powders for IR transparent windows  

Microsoft Academic Search

Polycrystalline infrared transparent materials with good optical and mechanical properties are needed for the fabrication of infrared windows and domes. We have developed a synthesis process to produce MgO nanopowders. The average aggregate size of powder is in the range of 150 - 160 nm, with a narrow aggregate size distribution. Additionally, a protocol for compaction of nanocrystalline powders to

Mohit Jain; Ganesh Skandan; Amit Singhal; Dinesh Agrawal; Yi Feng; Joseph La Monica; J. Kirsch

2005-01-01

275

Metallurgy, environmental pollution and the decline of Etruscan civilisation  

Microsoft Academic Search

Background, aim and scopeThe 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, MontAmiata and Elba). We offer a new perspective on certain Iron Age\\u000a and Archaic (ca. 1,000480bc) 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

276

Highly efficient induction heating units for metallurgy and machine construction  

Microsoft Academic Search

Induction heating units are being used increasingly widely in metallurgy and machine construction in all industrially developed\\u000a nations: in metalhurgyto refine ferrous, nonferrous, and noble metals, including in vacuums; in machine constructionfor\\u000a quenching, soldering, annealing, stamping, hard-facing, and other operations. The reason is the possibility of moving products\\u000a at high speeds in such furnaces within a precisely prescribed heating zone

L. I. Faerman; V. I. Luzgin; A. Yu. Petrov; S. A. Rachkov

1997-01-01

277

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

278

3.40J / 22.71J Physical Metallurgy, Spring 2003  

E-print Network

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

Russell, Kenneth

279

Characterization of Fine Powders  

NASA Astrophysics Data System (ADS)

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

Krantz, Matthew; Zhang, Hui; Zhu, Jesse

280

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

281

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

282

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

283

Welding Metallurgy and Processing Issues for Joining of Power Sources  

SciTech Connect

Weldability issues with the pertinent alloys have been reviewed and preliminary results of our work on Haynes 25 have been presented. Further results on the mechanical properties and metallography on the EB welds are imminent. Hot-ductility experiments will commence within a few weeks. Aging studies on the effects of heat treatment using the Gleeble are also planned. MST-6 has extensive background in the welding metallurgy of the pertinent alloys. We also have considerable experience with the various welding processes to be used.

Lienert, Thomas J. [Los Alamos National Laboratory; Reardon, Patrick T. [Los Alamos National Laboratory

2012-08-14

284

Chloride metallurgy: PGM recovery and titanium dioxide production  

NASA Astrophysics Data System (ADS)

This paper examines in detail the thermodynamics and application of chloride metallurgy for the extraction of precious metals, such as gold and silver, and platinum-group metals. The advantages with regard to the solubilities of metal ion species and their reduction potentials in chloride media are discussed with examples. The use of chloride media for the extraction of platinum-group metals from spent autocatalysts and for the production of high-purity pigment-grade TiO2 and titanium metal from ilmenite feed stocks is discussed in the case studies provided.

Puvvada, G. V. K.; Sridhar, R.; Lakshmanan, V. I.

2003-08-01

285

Microstructural Development in Al-Si Powder During Rapid Solidification  

SciTech Connect

Powder metallurgy has become an increasingly important form of metal processing because of its ability to produce materials with superior mechanical properties. These properties are due in part to the unique and often desirable microstructures which arise as a result of the extreme levels of undercooling achieved, especially in the finest size powder, and the subsequent rapid solidification which occurs. A better understanding of the fundamental processes of nucleation and growth is required to further exploit the potential of rapid solidification processing. Aluminum-silicon, an alloy of significant industrial importance, was chosen as a model for simple eutectic systems displaying an unfaceted/faceted interface and skewed coupled eutectic growth zone, Al-Si powder produced by high pressure gas atomization was studied to determine the relationship between microstructure and alloy composition as a function of powder size and atomization gas. Critical experimental measurements of hypereutectic (Si-rich) compositions were used to determine undercooling and interface velocity, based on the theoretical models which are available. Solidification conditions were analyzed as a function of particle diameter and distance from nucleation site. A revised microstructural map is proposed which allows the prediction of particle morphology based on temperature and composition. It is hoped that this work, by providing enhanced understanding of the processes which govern the development of the solidification morphology of gas atomized powder, will eventually allow for better control of processing conditions so that particle microstructures can be optimized for specific applications.

Amber Lynn Genau

2004-12-19

286

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

287

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

288

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

289

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....

290

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

291

Wrought processing of ingot-metallurgy gamma titanium aluminide alloys  

SciTech Connect

The wrought processing of ingot-metallurgy, gamma titanium aluminide alloys is reviewed. Attention is focused on five major areas in the development of thermomechanical processes for these materials: (1) ingot structure and homogenization, (2) ingot breakdown via existing techniques, (3) novel processes for ingot breakdown, (4) secondary processing, and (5) process scaleup considerations. The nature of the cast microstructure and the influence of composition and ingot size on grain size and segregation are described. The design of existing processes for ingot breakdown deals with the selection of process variables and the design of cans for nonisothermal metalworking techniques. Novel breakdown processes, including smart forging, alpha forging, controlled dwell extrusion, and equal channel angular extrusion, are reviewed. In the area of secondary processing, developments related to pack rolling of sheet, superplastic sheet forming, and isothermal, closed-die forging are summarized. Lastly, scaleup considerations such as thermal cracking during ingot production are addressed.

Semiatin, S.L. [Wright Lab., Wright-Patterson AFB, OH (United States). Materials Directorate

1995-12-31

292

Oxide Dispersion Strengthened Iron Aluminide by CVD Coated Powders  

SciTech Connect

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

Asit Biswas Andrew J. Sherman

2006-09-25

293

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

294

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.

295

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

296

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

297

A compact optical fiber scanner for medical imaging  

Microsoft Academic Search

A compact fiber optic scanner for biomedical applications such as optical coherent tomography has been designed, fabricated and tested. The scanner is designed as an in vivo device and composed of an optical fiber coated with nickel-powder loaded paint for external magnetic actuation. The compactness of the imaging device makes it suitable for applications where size, precision and low power

Naresh Dhaubanjar; Hans Hu; Digent Dave; Pratibha Phuyal; Jeongsik Sin; Harry Stephanou; J.-C. Chiao

2007-01-01

298

Sintered Diamond Compacts with a Cobalt Binder  

Microsoft Academic Search

Diamond powder can be successfully cemented with cobalt. At 62 kilobars the sintering occurs over the temperature range from 1570 degrees to 1610 degrees C. The maximum microhardness of the compact (> 3000 kilograms per square millimeter on the Knoop scale) is obtained with a mixture of 20 percent cobalt (by volume) and a diamond particle size of 1 to

Howard Katzman; W. F. Libby

1971-01-01

299

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

Microsoft Academic Search

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

Edward D. Derr; Ronald E. Wieneke

2000-01-01

300

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

301

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

302

Microstructural development during consolidation of rapidly solidified Al-Fe-V-Si powder by VHP, extrusion and rolling  

SciTech Connect

The rapid solidification of powder results in a high cooling rate which leads to microstructural refinement and extended solid solubility of alloying elements and thereby precipitation of fine dispersive phases during powder solidification and consolidation. During the last decade considerable research work has been done in the development of high temperature powder metallurgy aluminum alloys capable of competing with titanium alloys on a specific strength basis with the use of rapid solidification processes. The Al-Fe-V-Si family of alloys are one of the most promising on a basis of elevated temperature strength, stiffness and thermal stability. In previous studies, the Al-Fe-V-Si alloys were usually produced by melt spinning (both jet casting and planar flow casting) followed by consolidation of the resulting ribbons. The aim of the present study was to investigate the microstructural development of atomized Al-Fe-V-Si alloy powder during consolidation by vacuum hot pressing (VHP), extrusion and rolling.

Wang, Y.; Lorimer, G.W.; Sale, F.R. (Univ. of Manchester (United Kingdom). Manchester Materials Science Centre)

1994-11-15

303

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

304

Direct consolidation of TiAl-X alloy from elemental powder mixture  

SciTech Connect

Intermetallic compounds based on near [gamma] TiAl composition have drawn research attention due to their high specific strength, creep resistance and oxidation resistance required for elevated temperature application. Of the two approaches which produce the intermetallic compound, ingot metallurgy and powder metallurgy, the latter route has the merit of good room temperature tensile ductility because of the fine grain size. To obtain a full density by the powder metallurgical approach, however, is not always an easy task. Reactive sintering alone, for example, does not yield a full density in this alloy system. Recently, Kim et al. showed that a combination of low temperature extrusion and reactive sintering in a hot isostatic press was a viable route to obtain the full density. An alternative, less expensive way, is presented in this paper. In previous work, the authors reported the production of a full density Ni[sub 3]Al intermetallic compound through a direct hot extrusion of blended elemental powder mixture. In the present work, the authors attempted to extend the method to TiAl-X alloys and obtained a promising result.

Lee, I.S.; Hwang, S.K.; Park, W.K.; Lee, J.H.; Park, D.H. (Inha Univ., Inchon (Korea, Republic of). Dept. of Metallurgical Engineering); Kim, H.M.; Lee, Y.T. (Korean Institute of Machinery and Metals, Changwon (Korea, Republic of))

1994-07-01

305

Magnetic properties of high silicon iron sheet fabricated by direct powder rolling  

Microsoft Academic Search

In this research, the high siliconiron strips (near to 6.5%Si) were produced by the direct powder rolling (DPR) technique. The continuous strips could be compacted by rolling from silicon and iron powders and sintered by the following heat treatments. The chemical formula, Fe+Si?Fe (Si)+Fe3Si (Si), controls the reaction of silicon and iron powders. Optimized mechanical properties of the strip due

Ran Li; Qiang Shen; Lianmeng Zhang; Tao Zhang

2004-01-01

306

Applications of high-temperature powder metal aluminum alloys to small gas turbines  

NASA Technical Reports Server (NTRS)

A program aimed at the development of advanced powder-metallurgy (PM) aluminum alloys for high-temperature applications up to 650 F using the concepts of rapid solidification and mechanical alloying is discussed. In particular, application of rapidly solidified PM aluminum alloys to centrifugal compressor impellers, currently used in auxiliary power units for both military and commercial aircraft and potentially for advanced automotive gas turbine engines, is examined. It is shown that substitution of high-temperature aluminum for titanium alloy impellers operating in the 360-650 F range provides significant savings in material and machining costs and results in reduced component weight, and consequently, reduced rotating group inertia requirements.

Millan, P. P., Jr.

1982-01-01

307

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

308

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...

309

Pyrotechnic filled molding powder  

DOEpatents

The disclosure relates to thermosetting molding compounds and more particularly to a pyrotechnic filled thermosetting compound comprising a blend of unfilled diallyl phthalate molding powder and a pyrotechnic mixture.

Hartzel, Lawrence W. (Dayton, OH); Kettling, George E. (Cincinnati, OH)

1978-01-01

310

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

311

[Otologic diagnosis: powder technique].  

PubMed

The otologic diagnostic powder test with grape - sugar simple will be performed with a powder - blower. It permits a good differentiation between dry squamous epithelium and wet mucosa. In our opinion this test therefore is unrenouncable in microscopic differentiation between mucosa in central perforations on one hand and atrophic scars, retraction pockets or adhesive epithelium of the drum or complete atelectasis of the tympanic cavity on the other hand. PMID:21626473

Tolsdorff, P

2011-06-01

312

Under bump metallurgy study for Pb-free bumping  

NASA Astrophysics Data System (ADS)

The demand for Pb-free and high-density interconnection technology is rapidly growing. The electroplating-bumping method is a good approach to meet finepitch requirements, especially for high-volume production, because to volume change of patterned-solder bumps during reflow is not so large compared with the stencil-printing method. This paper proposes a Sn/3.5 Ag Pb-free electroplating-bumping process for high-density Pb-free interconnects. It was found that a plated Sn/Ag bump becomes Sn/Ag/Cu by reflowing when Cu containing under bump metallurgy (UBM) is used. Another important issue for future flip-chip interconnects is to optimize the UBM system for high-density and Pb-free solder bumps. In this work, four UBM systems, sputtered TiW 0.2 m/Cu 0.3 m/electroplated Cu 5 m, sputtered Cr 0.15 m/Cr-Cu 0.3 m/Cu 0.8 m, sputtered NiV 0.2 m/Cu 0.8 m, and sputtered TiW 0.2 m/NiV 0.8 m, were investigated for interfacial reaction with electroplated Pb/63Sn and Sn/3.5Ag solder bumps. Both Cu-Sn and Ni-Sn intermetallic compound (IMC) growth were observed to spall-off from the UBM/solder interface when the solder-wettable layer is consumed during a liquid-state reflow process. This IMC-spalling mechanism differed depending on the barrier layer material.

Jang, Se-Young; Wolf, Juergen; Paik, Kyung-Wook

2002-05-01

313

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 Hnninen; Jukka Paro; Veijo Kauppinen

1996-01-01

314

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

315

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

316

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

E-print Network

and environmentally safer methods ought to be devised. This is more relevant to the pharmaceutical and chemical performance, such as, several time-consuming steps of grinding, milling, heating, etc. [2]. This translates environmentally benign. The alkaline-earth stannates having the general chemical formula MSnO3 (M Ca, Sr and Ba

Azad, Abdul-Majeed

317

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

318

Effects of C and Hf concentration on the mechanical properties of wrought superalloys based on NASA IIB-11 produced from prealloyed powders  

NASA Technical Reports Server (NTRS)

This work describes the effects of C and Hf concentration on the mechanical properties of NASA IIB-11, a candidate material for advanced-temperature gas turbine engine disks. IIB-11 and four alloys of varied C and Hf concentrations were produced as cross-rolled disks from hot-isostatically pressed powder billets. The lower C, higher Hf modification exhibited the best mechanical properties at 760 C and below. These properties were at least equivalent to those of other candidate alloys for advanced temperature disks. Because of their finer grain sizes, all of these powder metallurgy alloys had lower rupture strength, however, than that achieved previously in conventionally processed IIB-11.

Miner, R. V., Jr.

1976-01-01

319

Powder Processing of Fiber-Reinforced Ceramics: Strengthening of the Powder Matrix Without Shrinkage. Ph.D. Thesis  

SciTech Connect

Powder processing of fiber-reinforced ceramic matrix composites is limited by constrained densification if the powder matrix is allowed to shrink during heat treatment. This produces large, strength-limiting crack-like voids. The objective of this study was to avoid this damage phenomenon by strengthening the powder matrix without shrinkage by using the cyclic infiltration/pyrolysis of ceramic liquid precursors. The following issues were addressed: (1) liquid precursor infiltration kinetics, (2) microstructural development during heat treatment, and (3) the mechanical properties of the porous bodies thus produced. Si3N4 powder matrices were infiltrated with either Zr(Y)-nitrate, which produces ZrO2, or polysilazane, which converts to Si3N4 during pyrolysis. Infiltration kinetics were shown to depend on the permeability of the powder compact, as well as that of the intruded material developed after heat treatment. The large volume changes during precursor pyrolysis is manifested by the formation of randomly distributed voids, which coalesce at higher temperatures. In this study, the powder matrix cannot be made fully dense; its fracture toughness was found to increase proportionally with the fraction of filled porosity and with the fracture toughness of the intruded material. The fracture strength appeared to follow the same trend. However, relatively strong bodies can be obtained despite high porosity, provided that the strength-limiting flaws are small. Large cracks are introduced in the powder matrix during infiltration if a layer of precursor remains on the surface. Cracks which develop in the precursor layer can extend into the matrix. Fracture mechanisms of thin films-on-substrates under residual thermal stress were used to explain this phenomenon. Matrix damage can be avoided by removing the precursor layer prior to pyrolysis and/or by strengthening the powder compact before infiltration.

Tu, Wen-chiang

1994-01-01

320

Critical evaluation of root causes of the reduced compactability after roll compaction/dry granulation.  

PubMed

The influence of lubrication and particle size on the reduced compactability after dry granulation was investigated. Powder cellulose, lactose, magnesium carbonate, and two types of microcrystalline cellulose were roll compacted, granulated, and sieved into particle fractions. Particle fractions were compressed into tablets using internal and external lubrication. Internal lubrication resulted in an overlubrication of the granule material compared with the powder material. This resulted in extraordinary high reduction of compactability after dry granulation for lubricant-sensitive materials. The granule size can cause differences in strength, whereby the degree of this effect was material dependent. The loss in strength with increasing compaction force was comparable for different particles sizes of one material, suggesting a change in material properties independently of the size. Granule hardening could be one reason as for higher compaction forces the integrity of the granule structure survived the compression step. The results demonstrated that granule lubrication mainly influence the degree of the reduced compactability after dry granulation and must be considered for the evaluation of mechanism for this phenomenon. Hardening of the material as well as size enlargement will cause the loss in strength after recompression, but the influence of both depends strongly on the material. 2015 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 104:1108-1118, 2015. PMID:25558976

Mosig, Johanna; Kleinebudde, Peter

2015-03-01

321

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 3,000F 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

322

Investigation of Soap Powders  

E-print Network

pound , Price 5 cents. Analysis Moisture 13.36$ Soap 38.96$ NaaCOa 45.44$ Total 97.76$ C Q H C L U S I O B . To facilitate comparison, the following table has been compiled, showing at a glance the relative compositions of the powders... Price 5 cents. Analysis. Moisture 13.69$ Soap 30.86$ N aC0 3 .. 55.41$ Total 99.96$ Wizard Washing Powder. Manufactured by Floor Clean Company, Chicago. Wt. 1 pound Price 5 cents. Analysis. Moisture 16.54$ Soap 13.24$ Na 2C0 3 68.38$ Total...

Bragg, G.A.

1913-01-01

323

Iowa Powder Atomization Technologies  

ScienceCinema

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 3,000F 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

2013-03-01

324

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

325

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 30 20 10 mm by powder metallurgy route. All these toroid cores were cured at different temperatures ranging from 600C to 1000C 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 800C 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

326

The Application of Thermal Plasma to Extraction Metallurgy and Related Fields  

NASA Technical Reports Server (NTRS)

Various applications of thermal plasma to extraction metallurgy and related fields are surveyed, chiefly on the basis of documents published during the past two or three years. Applications to melting and smelting, to thermal decomposition, to reduction, to manufacturing of inorganic compounds, and to other fields are considered.

Akashi, K.

1980-01-01

327

University of Cambridge, Materials Science & Metallurgy H. K. D. H. Bhadeshia Differential Scanning Calorimetry  

E-print Network

input to the two furnaces; the energy required to do this is a measure of the enthalpy or heat capacity or heat capacity changes in the sample cause a difference in its temperature relative to the referenceUniversity of Cambridge, Materials Science & Metallurgy H. K. D. H. Bhadeshia Differential Scanning

Cambridge, University of

328

FORMALIZATION OF WASTE MANAGEMENT PROGRAMS IN SUPPORT OF THE CHEMISTRY AND METALLURGY RESEARCH FACILITY AUTHORIZATION BASIS  

Microsoft Academic Search

The Chemistry and Metallurgy Research (CMR) Facility conducts analytical operations that are vital to the Stockpile Stewardship Program at Los Alamos National Laboratory (LANL). From 1952 to the early 1990s, this facility operated without a Safety Analysis Report (SAR) and bounded the risks associated with its diverse operations. An Interim Safety Analysis Report (ISAR) prepared in 1992, served until further

Richard C. Stupka; Lisa P. Stringfield

2000-01-01

329

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

330

Fabrication and characterization of nanocrystalline Al/Al12(Fe,V)3Si alloys by consolidation of mechanically alloyed powders  

NASA Astrophysics Data System (ADS)

The aim of this study was to produce bulk nanocrystalline Al/Al12(Fe,V)3Si alloys by mechanical alloying (MA) and subsequent hot pressing (HP) of elemental powders. A nanostructured Al-based solid solution was formed by MA of elemental powders for 60 h. After HP of the as-milled powders at 550C for 20 min, the Al12(Fe,V)3Si phase was precipitated in a nanocrystalline Al matrix. Scanning electron microscopy (SEM) images of the bulk samples represented a homogeneous and uniform microstructure that was superior to those previously obtained by rapid solidification-powder metallurgy (RS-PM). Nanostructured Al-8.5Fe-1.3V-1.7Si and Al-11.6Fe-1.3V-2.3Si alloys exhibited high HV hardness values of 205 and 254, respectively, which are significantly higher than those reported for the RS-PM counterparts.

Ashrafi, Hamid; Emadi, Rahmatollah; Enayati, Mohammad Hosein

2014-07-01

331

The impermeability mechanism of self-compacting water proof concrete  

Microsoft Academic Search

The impermeability mechanism of water-proof self-compacting concrete (WPSCC) was studied. The mechanism and influential factors,\\u000a such as water-cement ratio (w\\/c), dosage of powder, superplasticizer, sand content, aggregate content, fly ash, UEA, PP fiber,\\u000a on compactibility and crack resistance of WPSCC were analyzed. A type of WPSCC successfully applied in tunnel liner with its\\u000a validities, conveniences and economies by mockup test

Li Huoxiang; Tang Chunan; Xiong Jianmin; Li Sinian

2005-01-01

332

Method to blend separator powders  

DOEpatents

A method for making a blended powder mixture, whereby two or more powders are mixed in a container with a liquid selected from nitrogen or short-chain alcohols, where at least one of the powders has an angle of repose greater than approximately 50 degrees. The method is useful in preparing blended powders of Li halides and MgO for use in the preparation of thermal battery separators.

Guidotti, Ronald A. (Albuquerque, NM); Andazola, Arthur H. (Albuquerque, NM); Reinhardt, Frederick W. (Albuquerque, NM)

2007-12-04

333

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

334

Ordinal Compactness Paolo Lipparini  

E-print Network

of [, ]-compact- ness. #12;Throughout, let be infinite ordinals. Definition 1 We say that a topological space- ness are the following: [, ]-compactness is equivalent to [, ]-com- pactness, for every with [cf, cf]-compactness implies [, ]-compact- ness. On the other hand, there are many more non- trivial

Lipparini, Paolo

335

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.

336

Effect of alloying impurities and conditions of heat treatment of iron-based powder materials and their magnetic properties  

Microsoft Academic Search

The structure of the initial iron powders, the type of alloying impurities, and the conditions of compaction and heat treatment of materials have been studied from the standpoint of their effect on the magnetic properties. Ways of enhancing the properties of magnetically-soft iron-based powder materials are recommended and methods of studying them are suggested.

G. I. Yaglo; V. M. Vasil'ev; O. A. Panasyuk

1995-01-01

337

Effect of alloying impurities and conditions of heat treatment of iron-based powder materials and their magnetic properties  

Microsoft Academic Search

The structure of the initial iron powders, the type of alloying impurities, and the conditions of compaction and heat treatment of materials have been studied from the standpoint of their effect on the magnetic properties. Ways of enhancing the properties of magnetically-soft iron-based powder materials are recommended and methods of studying them are suggested.

G. I. Yago; O. A. Panasyuk

1994-01-01

338

Processing polymeric powders  

NASA Technical Reports Server (NTRS)

The concept of uniformly and continuously depositing and sinter-fusing nominal 0.1 to 40 microns dimensioned electrostatically charged polymer powder particles onto essentially uniformly spread 5 to 20 micron grounded continuous fiber tow to produce a respoolable thermoplastic composite two-preg was formulated at NASA Langley. The process was reduced to practice under a NASA grant at the University of Akron this spring. The production of tow-preg is called phase 1. The production of ultrafine polymer powders from 5 to 10 percent (wt) polymer solids in solvent is considered. This is phase 0 and is discussed. The production of unitape from multi tow-pregs was also considered. This is phase 2 and is also discussed. And another approach to phase 1, also proposed last summer, was scoped. This is phase 1A and is also discussed.

Throne, James L.

1989-01-01

339

Explosive reaction pressing of intermetallic compounds from stoichiometric powder mixtures  

SciTech Connect

Intermetallic NiAl, TiAl, and TiAl{sub 3} were synthesized by shock compression experiments from stoichiometric powder mixtures of nickel and aluminium as well as of titanium and aluminium. Good consolidation and complete intermetallic reaction were achieved by the direct method of explosive compaction. For each powder mixture, a certain individual threshold pressure has to be exceeded in order to initiate intermetallic reaction. The reacting compounds melted completely with subsequent rapid solidification during the passage of the shock wave. The new material shows high hardness. Pores are formed by gaseous reaction products in the NiAl and TiAl{sub 3} compacts. The TiAl structure is fully-dense and dendritic.

Kochsiek, D.; Pruemmer, R.; Brunold, A. [Ernst-Mach-Institut of the Fraunhofer Research Association, Freiburg (Germany)

1995-09-01

340

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 which are capable of exhibiting superconductor properties upon subsequent appropriate treatment. The bath is continually energized to cause the metallic and/or reduced 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 all metals 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)

1998-01-01

341

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

342

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 750C 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 620C 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

343

Estimation and characterization of PCDD\\/Fs and dioxin-like PCBs from secondary copper and aluminum metallurgies in China  

Microsoft Academic Search

The secondary metallurgy industry is considered as one source of polychlorinated dibenzo-p-dioxin and dibenzofurans (PCDD\\/Fs). This study investigated the emission factors and total emissions amounts of PCDD\\/Fs and dioxin-like polychlorinated biphenyls (dioxin-like PCBs) released from secondary aluminum and copper metallurgy industries in China. The congener patterns are shown and the formation mechanism is also discussed in this paper.The toxic equivalency

Te Ba; Minghui Zheng; Bing Zhang; Wenbin Liu; Ke Xiao; Lifei Zhang

2009-01-01

344

Structural evolution in mechanically alloyed Al-Fe powders  

SciTech Connect

The structural evolution in mechanically alloyed binary aluminum-iron powder mixtures containing 1, 4, 7.3, 10.7, and 25 at pct Fe was investigated using X-ray diffraction (XRD) and electron microscopic techniques. The constitution (number and identity of phases present), microstructure (crystal size, particle size), and transformation behavior of the powders on annealing were studied. The solid solubility of Fe in Al has been extended up to at least 4.5 at. pct, which is close to that observed using rapid solidification (RS) (4.4 at. pct), compared with the equilibrium value of 0.025 at. pct Fe at room temperature. Nanometer-sized grains were observed in as-milled crystalline powders in all compositions. Increasing the ball-to-powder weight ratio (BPR) resulted in a faster rate of decrease of crystal size. A fully amorphous phase was obtained in the Al-25 at. pct Fe composition, and a mixed amorphous phase plus solid solution of Fe in Al was developed in the Al-10.7 at. pct Fe alloy, agreeing well with the predictions made using the semiempirical Miedema model. Heat treatment of the mechanically alloyed powders containing the supersaturated solid solution or the amorphous phase resulted in the formation of the Al{sub 3}Fe intermetallic in all but the Al-25 at. pct Fe powders. In the Al-25 at. pct Fe powder, formation of nanocrystalline Al{sub 5}Fe{sub 2} was observed directly by milling. Electron microscope studies of the shock-consolidated mechanically alloyed Al-10.7 and 25 at. pct Fe powders indicated that nanometer-sized grains were retained after compaction.

Mukhopadhyay, D.K.; Suryanarayana, C.; Froes, F.H. [Univ. of Idaho, Moscow, ID (United States)

1995-08-01

345

Powder Processing of High Temperature Cermets and Carbides at Marshall Space Flight Center  

NASA Technical Reports Server (NTRS)

The Materials and Processing Laboratory at NASA Marshall Space Flight Center is developing Powder Metallurgy (PM) processing techniques for high temperature cermet and carbide material consolidation. These new group of materials would be utilized in the nuclear core for Nuclear Thermal Rockets (NTR). Cermet materials offer several advantages for NTR such as retention of fission products and fuels, better thermal shock resistance, hydrogen compatibility, high thermal conductivity, and high strength. Carbide materials offer the highest operating temperatures but are sensitive to thermal stresses and are difficult to process. To support the effort, a new facility has been setup to process refractory metal, ceramic, carbides and depleted uranium-based powders. The facility inciudes inert atmosphere glove boxes for the handling of reactive powders, a high temperature furnace, and powder processing equipment used for blending, milling, and sieving. The effort is focused on basic research to identify the most promising compositions and processing techniques. Several PM processing methods including Cold and Hot Isostatic Pressing are being evaluated to fabricate samples for characterization and hot hydrogen testing.

Salvail, Pat; Panda, Binayak; Hickman, Robert R.

2007-01-01

346

Estimation and characterization of polycyclic aromatic hydrocarbons from magnesium metallurgy facilities in China.  

PubMed

Field monitoring was conducted to develop a polycyclic aromatic hydrocarbon (PAH) emission inventory for the magnesium (Mg) metallurgy industry in China. PAH emissions in stack gas and fly/bottom ash samples from different smelting units of a typical Mg smelter were measured and compared. Large variations of concentrations, congener patterns, and emission factors of PAHs during the oxidation and reduction stages in the Mg smelter were observed. The measured average emission factor (166,487 ?g/t Mg) was significantly higher than those of other industrial sources. Annual emission from Mg metallurgy in 2012 in China was estimated at 116 kg (514 g BaPeq) for PAHs. The results of this study suggest that PAH emission from Mg industries should be considered by local government agencies. These data may be helpful for understanding PAH levels produced by the Mg industry and in developing a PAH inventory. PMID:24958530

Nie, Zhiqiang; Yang, Yufei; Tang, Zhenwu; Liu, Feng; Wang, Qi; Huang, Qifei

2014-11-01

347

Metallurgy. technical activities, 1995. Report for 1 October 1994-30 September 1995  

SciTech Connect

The report describes the technical activities of the Metallurgy Division in 1995. The format this year is different from that in preceding years in that the descriptions of the Division`s projects are grouped under major Materials Science and Engineering Laboratory (MSEL) program rather than under specific Groups. Partial Table of Contents: Intelligent Processing of Materials; High-Tc Superconductivity; Electronic Packaging and Interconnection; Nanostructured Materials; Dental and Medical Materials; MSEL Other; Metals Processing; Metals Data and Characterization.

Pugh, E.N.; Hardy, S.C.

1995-12-31

348

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

Microsoft Academic Search

In flip chip interconnection on organic substrates using eutectic Pb\\/Sn 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\\/O.2 ?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

Se-Young Jang; Kyung-Wook Paik

1998-01-01

349

Environmental concerns in extractive metallurgy. (Latest citations from METADEX). Published Search  

SciTech Connect

The bibliography contains citations concerning pollution control in the extractive metallurgical industry. Articles discuss disposal of waste solids resulting from ore processing, treatment of waste water, recovery of particulate fines, material recovery from waste water, and remediation of waste streams from extractive metallurgy. Citations address processing of copper, gold, zinc, uranium, iron, lead, and other metal materials and metal-bearing ores. (Contains a minimum of 152 citations and includes a subject term index and title list.)

Not Available

1994-09-01

350

Dense silicon carbonitride ceramics by pyrolysis of cross-linked and warm pressed polysilazane powders  

Microsoft Academic Search

This study reports on the pyrolysis and densifaction behavior of cross-linked poly(hydridomethylsilazane) powders. The influence of the cross-linking procedure such as temperature and annealing time of the polymer powders on the compaction behavior under cold and warm pressing conditions is discussed. The degree of cross-linking is determined by thermal mechanical analysis (TMA). In addition to particle sliding which is assumed

Christoph Konetschny; Dusan Galusek; Stefan Reschke; Claudia Fasel; Ralf Riedel

1999-01-01

351

Shock wave loading of Nickel based superalloy and microstructural features of the compacts  

NASA Astrophysics Data System (ADS)

Explosive shock wave loading has been employed to consolidate micro-sized nickel based IN718 superalloy powder. Cylindrical geometry configuring the various critical parameters with optimized detonation pressure has been used to consolidate the powder with desirable means. The thrust on the work is to compact the powder nearer to theoretical density having almost negligible density gradient and without melting the core of the specimen. XRD study indicates that the crystal structure of the post compacts remains the same. Shock wave loading deformed the particles as has been inferred from SEM. The variation in particle size has been measured from Laser Diffraction based Particle Size Analyzer (LDPSA). It is found that this is a rapid fast technique to produce larger and crack free compacts of metal powders without their melting and with less particle size variation.

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

2015-02-01

352

Comminution of stainless steel powders  

Microsoft Academic Search

1.Atmospheric milling in barrel type mixers at a powder-to-ball weight ratio of 1::2 is an effective means of comminuting stainless steel powders produced by the coreduction process. In the work described, milling for 27 h was found to increase the amount of the -0.063-mm fraction from ~15 to ~75% for a Kh18N15 steel powder and from ~24.6 to ~70%for a

B. A. Borok; R. P. Schchegoleva; L. S. Golubeva; F. S. Sariadi; E. M. Rabinovich

1974-01-01

353

Polymer powder prepregging: Scoping study  

NASA Technical Reports Server (NTRS)

Early on, it was found that NEAT LARC-TPI thermoplastic polyimide powder behaved elastoplastically at pressures to 20 ksi and temperatures to 260 degrees celcius (below MP). At high resin assay, resin powder could be continuously cold-flowed around individual carbon fibers in a metal rolling mill. At low resin assay (2:1, C:TPI), fiber breakage was prohibitive. Thus, although processing of TPI below MP would be quite unique, it appears that the polymer must be melted and flowed to produce low resin assay prepreg. Fiber tow was spread to 75 mm using a venturi slot tunnel. This allowed intimate powder/fiber interaction. Two techniques were examined for getting room temperature powder onto the room temperature fiber surface. Electrostatic powder coating allows the charged powder to cling tenaciously to the fiber, even while heated with a hot air gun to above its melt temperature. A variant of the wet slurry coating process was also explored. The carbon fibers are first wetted with water. Then dry powder is sprinkled onto the wet tow and doctor-rolled between the fibers. The wet structure is then taken onto a heated roll, with hot air guns drying and sinter-melting the powder onto the fiber surfaces. In both cases SEM shows individual fibers coated with powder particles that have melted in place and flowed along the fiber surface via surface tension.

Throne, James L.

1988-01-01

354

Differential compaction behaviour of roller compacted granules of clopidogrel bisulphate polymorphs.  

PubMed

In the present work, in-die and out-of-die compaction behaviour of dry-granulated powders of clopidogrel bisulphate (CLP) polymorphs, form I and form II, was investigated using a fully instrumented rotary tablet press. Each polymorph was compacted at three different roller pressures [70.3 (S1), 105.5 (S2) and 140.6 (S3)kgf/cm(2)], and obtained granules were characterized for their physico-mechanical properties. Compaction data were analyzed for out-of-die compressibility, tabletability and compactibility profiles, and in-die Heckel, Kawakita and Walker analysis. The roller compacted granules of both forms showed markedly different tabletting behaviour. Roller pressure exhibited a trend on compaction behaviour of form I granules, whereas, in case of form II, the effect was insignificant. Tabletability of the six granule batches follows the order; I_S1>I_S2>I_S3>II_S1?II_S2?II_S3. In case of form I, the reduced tabletability of the granules compacted at higher roller pressure was attributed to the decreased compressibility and plastic deformation. This was confirmed by compressibility plot and various mathematical parameters derived from Heckel (Py), Kawakita (1/b) and Walker (W) equations. The reduced tabletability of form I granules was due to 'granule hardening' during roller compaction. On the other hand, insignificant effect of roller compaction on tabletting behaviour of form II granules was attributed to brittle fragmentation. The extensive fragmentation of granules offered new 'clean' surfaces and higher contact points that negated the effect of granule hardening. PMID:24971694

Khomane, Kailas S; Bansal, Arvind K

2014-09-10

355

Wear mechanisms in high speed steel reinforced with (NbC)p and (TaC)p MMCs  

Microsoft Academic Search

Powder metallurgy techniques were used to manufacture metal matrix composites. M3\\/2 high-speed steel was used as the matrix, and NbC and TaC, in different percentages, as reinforcements. Graphite was added to the M3\\/2 powders, to compensate carbon losses during sintering, and copperphosphorous (CuP) to promote liquid phase sintering. The conventional powder metallurgy (P\\/M) route consists of dry mixing, uniaxially compacting

E Gordo; F Velasco; N Antn; J. M Torralba

2000-01-01

356

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

357

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

358

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

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

Effects of long-time elevated temperature exposures on hot-isostatically-pressed power-metallurgy Udimet 700 alloys with reduced cobalt contents  

NASA Technical Reports Server (NTRS)

Because almost the entire U.S. consumption of cobalt depends on imports, this metal has been designated "strategic'. The role and effectiveness of cobalt is being evaluated in commercial nickel-base superalloys. Udiment 700 type alloys in which the cobalt content was reduced from the normal 17% down to 12.7%, 8.5%, 4.3%, and 0% were prepared by standard powder metallurgy techniques and hot isostatically pressed into billets. Mechanical testing and microstructural investigations were performed. The mechanical properties of alloys with reduced cobalt contents which were heat-treated identically were equal or better than those of the standard alloy, except that creep rates tended to increase as cobalt was reduced. The effects of long time exposures at 760 C on mechanical properties and at 760 C and 845 C on microstructures were determined. Decreased tensile properties and shorter rupture lives with increased creep rates were observed in alloy modifications. The exposures caused gamma prime particle coarsening and formation of sigma phase in the alloys with higher cobalt contents. Exposure at 845 C also reduced the amount of MC carbides.

Hart, F. H.

1984-01-01

361

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

362

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

363

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

364

Flow and compaction behaviour of ultrafine coated ibuprofen.  

PubMed

Good flow and compaction properties are prerequisites for successful compaction process. Apart from initial profile, mechanical properties of pharmaceutical powders can get modified during unit processes like milling. Milled powders can exhibit a wide range of particle size distribution. Further downstream processing steps like compaction can be affected by this differential particle size distribution. This has greatest implications for formulations like high dose drugs wherein the active pharmaceutical ingredient (API) contributes the maximum bulk in the final formulation. The present study assesses the impact of dry coating with ultrafine particles of same material, on the flow and compaction properties of the core material. Ibuprofen was selected as model drug as it has been reported to have poor mechanical properties. Ultrafine ibuprofen (average size 1.75 ?m) was generated by Dyno() milling and was dry coated onto the core ibuprofen particles (average size 180 ?m). Compaction studies were performed using a fully instrumented rotary tablet press. Compaction data was analyzed for compressibility, tabletability, compactibility profiles and Heckel plot. Dry coating of the ibuprofen exhibited greater compressibility and tabletability, at lower compaction pressure. However, at compaction pressure above 220 MPa, compressibility and tabletability of coated as well as uncoated materials were found to be similar. Heckel analysis also supported the above findings, as P(y) value of uncoated ibuprofen was found to be 229.49 MPa and for 2.0% ultrafine coated ibuprofen was found to be 158.53 MPa. Lower P(y) value of ultrafine coated ibuprofen indicated ease of plastic deformation. Superior compressibility and deformation behaviour of ultrafine coated ibuprofen attributed to increased interparticulate bonding area. This strategy can also be explored for improving tabletability of high dose poorly compressible drugs. PMID:23142495

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

2013-01-30

365

Light extinction in metallic powder beds: Correlation with powder structure  

SciTech Connect

A theoretical correlation between the effective extinction coefficient, the specific surface area, and the chord length distribution of powder beds is verified experimentally. The investigated powder beds consist of metallic particles of several tens of microns. The effective extinction coefficients are measured by a light-transmission technique at a wavelength of 540 nm. The powder structure is characterized by a quantitative image analysis of powder bed cross sections resulting in two-point correlation functions and chord length distributions. The specific surface area of the powders is estimated by laser-diffraction particle-size analysis and by the two-point correlation function. The theoretically predicted tendency of increasing extinction coefficient with specific surface area per unit void volume is confirmed by the experiments. However, a significant quantitative discrepancy is found for several powders. No clear correlation of the extinction coefficient with the powder material and particle size, and morphology is revealed, which is in line with the assumption of geometrical optics.

Rombouts, M.; Froyen, L.; Gusarov, A.V.; Bentefour, E.H.; Glorieux, C. [Department Metaalkunde en Toegepaste Materiaalkunde, Katholieke Universiteit Leuven, Kasteelpark Arenberg 44, 3001 Leuven (Belgium); Baikov Institute of Metallurgy, Russian Academy of Sciences, Leninsky Prospect 49, 119991 Moscow (Russian Federation); Laboratorium voor Akoestiek en Thermische Fysica, Department Natuurkunde, Katholieke Universiteit Leuven, Celestijnenlaan 200D, 3001 Leuven (Belgium)

2005-07-01

366

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

PubMed

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

367

21 CFR 73.2647 - Copper powder.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false Copper powder. 73.2647 Section 73...CERTIFICATION Cosmetics 73.2647 Copper powder. (a) Identity and specifications. The color additive copper powder shall conform in identity...

2010-04-01

368

30 CFR 56.6901 - Black powder.  

Code of Federal Regulations, 2010 CFR

...Resources 1 2010-07-01 2010-07-01 false Black powder. 56.6901 Section 56.6901 Mineral... Explosives General Requirements 56.6901 Black powder. (a) Black powder shall be used for blasting only when a...

2010-07-01

369

21 CFR 73.2645 - Aluminum powder.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 2013-04-01 false Aluminum powder. 73.2645 Section 73...CERTIFICATION Cosmetics 73.2645 Aluminum powder. (a) Identity and specifications. The color additive aluminum powder shall conform in...

2013-04-01

370

21 CFR 73.1645 - Aluminum powder.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false Aluminum powder. 73.1645 Section 73.1645...CERTIFICATION Drugs 73.1645 Aluminum powder. (a) Identity. (1) The color additive aluminum powder shall be composed of finely...

2010-04-01

371

21 CFR 73.1645 - Aluminum powder.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 2013-04-01 false Aluminum powder. 73.1645 Section 73.1645...CERTIFICATION Drugs 73.1645 Aluminum powder. (a) Identity. (1) The color additive aluminum powder shall be composed of finely...

2013-04-01

372

21 CFR 73.2645 - Aluminum powder.  

Code of Federal Regulations, 2011 CFR

...2011-04-01 2011-04-01 false Aluminum powder. 73.2645 Section 73...CERTIFICATION Cosmetics 73.2645 Aluminum powder. (a) Identity and specifications. The color additive aluminum powder shall conform in...

2011-04-01

373

21 CFR 73.2645 - Aluminum powder.  

Code of Federal Regulations, 2014 CFR

...2014-04-01 2014-04-01 false Aluminum powder. 73.2645 Section 73...CERTIFICATION Cosmetics 73.2645 Aluminum powder. (a) Identity and specifications. The color additive aluminum powder shall conform in...

2014-04-01

374

21 CFR 73.2645 - Aluminum powder.  

Code of Federal Regulations, 2012 CFR

...2012-04-01 2012-04-01 false Aluminum powder. 73.2645 Section 73...CERTIFICATION Cosmetics 73.2645 Aluminum powder. (a) Identity and specifications. The color additive aluminum powder shall conform in...

2012-04-01

375

21 CFR 73.1645 - Aluminum powder.  

Code of Federal Regulations, 2014 CFR

...2014-04-01 2014-04-01 false Aluminum powder. 73.1645 Section 73.1645...CERTIFICATION Drugs 73.1645 Aluminum powder. (a) Identity. (1) The color additive aluminum powder shall be composed of finely...

2014-04-01

376

21 CFR 73.2645 - Aluminum powder.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false Aluminum powder. 73.2645 Section 73...CERTIFICATION Cosmetics 73.2645 Aluminum powder. (a) Identity and specifications. The color additive aluminum powder shall conform in...

2010-04-01

377

21 CFR 73.1645 - Aluminum powder.  

Code of Federal Regulations, 2012 CFR

...2012-04-01 2012-04-01 false Aluminum powder. 73.1645 Section 73.1645...CERTIFICATION Drugs 73.1645 Aluminum powder. (a) Identity. (1) The color additive aluminum powder shall be composed of finely...

2012-04-01

378

21 CFR 73.1645 - Aluminum powder.  

Code of Federal Regulations, 2011 CFR

...2011-04-01 2011-04-01 false Aluminum powder. 73.1645 Section 73.1645...CERTIFICATION Drugs 73.1645 Aluminum powder. (a) Identity. (1) The color additive aluminum powder shall be composed of finely...

2011-04-01

379

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

380

Predicting the shock compression response of heterogeneous powder mixtures  

NASA Astrophysics Data System (ADS)

A model framework for predicting the dynamic shock-compression response of heterogeneous powder mixtures using readily obtained measurements from quasi-static tests is presented. Low-strain-rate compression data are first analyzed to determine the region of the bulk response over which particle rearrangement does not contribute to compaction. This region is then fit to determine the densification modulus of the mixture, ?D, an newly defined parameter describing the resistance of the mixture to yielding. The measured densification modulus, reflective of the diverse yielding phenomena that occur at the meso-scale, is implemented into a rate-independent formulation of the P-? model, which is combined with an isobaric equation of state to predict the low and high stress dynamic compression response of heterogeneous powder mixtures. The framework is applied to two metal + metal-oxide (thermite) powder mixtures, and good agreement between the model and experiment is obtained for all mixtures at stresses near and above those required to reach full density. At lower stresses, rate-dependencies of the constituents, and specifically those of the matrix constituent, determine the ability of the model to predict the measured response in the incomplete compaction regime.

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

2013-06-01

381

Modified cellulose II powder: preparation, characterization, and tableting properties.  

PubMed

The reaction of UICEL-A/102, a cellulose II powder recently prepared from Avicel(R) PH-102 by treatment with an aqueous sodium hydroxide solution, with glutaraldehyde in 0.01 N HCl has been investigated to improve its binder properties, without adversely affecting the rapid disintegration characteristic. The results showed that UICEL-A/102 and glutaraldehyde when reacted in a 1:0.6 weight ratio at 100 degrees C for 8.5 h produces a product, (hereinafter referred to as UICEL-XL), that, compared to UICEL-A/102, had a lower degree of polymerization, higher crystallinity, lower bulk density, lower tapped density, and higher porosity. Further, it showed lower yield pressure and higher crushing strength, and tensile strength values, indicating that UICEL-XL is more compressible and compactable than the starting material, UICEL-A/102. A comparison of "in-die" and "out-of-die" Heckel data indicated UICEL-XL to be less elastic than UICEL-A/102. Both UICEL-XL and UICEL-A/102 showed similar moisture sorption isotherms, and their compacts disintegrated rapidly in water. In conclusion, the glutaraldehyde-treated cellulose II powder not only serves as good a disintegrant as the untreated cellulose powder but also possesses superior binder properties. PMID:17075860

de la Luz Reus Medina, Maria; Kumar, Vijay

2007-02-01

382

Molecular understanding of the compaction behavior of indomethacin polymorphs.  

PubMed

Polymorphs enable us to gain molecular insights into the compaction behavior of pharmaceutical powders. Two polymorphs (? and ?) of indomethacin (IMC) were investigated for in-die and out-of-die compaction behavior using compressibility, tabletability and compactibility (CTC) profile, stress-strain relationship, and Heckel, Kawakita and Walker equations. Compaction studies were performed on a fully instrumented rotary tabletting machine. CTC analysis revealed that the ?-form has increased compressibility while the ?-form showed greater compactibility. The ?-form also showed increased tabletability over the ?-form at all the compaction pressures. Lower values of Py (Heckel parameter) and 1/b (Kawakita parameter) indicated increased deformation behavior of ?-form. Stress-strain analysis also supports the increased compressibility of ?-form. In addition, Walker analysis showed higher compressibility coefficient (W) for ?-form, consistent with its greater tabletability. Thus, tabletability of IMC polymorphs was governed by the compactibility of the material. Detailed examination of crystallographic data revealed that the presence of a slip plane system in the ?-form offered it increased compressibility and deformation behavior. However, the ?-form showed greater compactibility by virtue of closer molecular packing (higher true density). Hence, although direct correlation between tabletability and the presence of slip planes in the crystals has been reported, prediction solely based on this crystallographic feature must be avoided. The present work reiterates the influence of the crystal packing on the tabletability of the pharmaceutical polymorphs. PMID:23301663

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

2013-02-01

383

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 which are capable of exhibiting superconductor properties upon subsequent appropriate treatment. The bath is continually energized to cause the metallic and/or reduced 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 all metals 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. 7 figs.

Bhattacharya, R.

1998-08-04

384

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

385

A study on high temperature oxidation behavior of double glow plasma surface metallurgy Fe-Al-Cr alloyed layer on Q235 steel  

NASA Astrophysics Data System (ADS)

The high-temperature oxidation behavior of Q235 steel coated with Fe-Al-Cr by using double glow plasma surface metallurgy method was studied in air at different temperatures of 500, 600 and 700 C, respectively. The Q235 and the 304 stainless steels were produced as the control samples. Electron microscopy, energy dispersive spectroscopy and X-ray diffractometry were carried out to investigate the surface morphologies, microstructures and phases of alloyed layer before and after oxidation. It showed that the structure of the Fe-Al-Cr alloyed layer was compact without any microstructure defects. This alloyed layer connected with the substrate metal by metallurgical bonding. At the temperatures of 500 and 600 C, the high temperature oxidation resistance of the Fe-Al-Cr alloyed layer was similar to that of the 304 steel, but 2-3 times higher than that of the Q235 steel. While at 700 C, the Fe-Al-Cr alloyed layer exhibited much better oxidation resistance than that of the 304 steel (2.5 times) and the Q235 steel (5.5 times). And this was because the special Al distribution (approximate Gaussian distribution) in the Fe-Al-Cr alloyed layer, which displayed the self-healing ability for the oxidation film on the surface of the Fe-Al-Cr alloyed layer in the high temperature oxidation conditions.

Luo, Xi-Xi; Yao, Zheng-Jun; Zhang, Ping-Ze; Miao, Qiang; Liang, Wen-Ping; Wei, Dong-Bo; Chen, Yu

2014-06-01

386

Processing and microstructural characterization of Al-Cu alloys produced from rapidly solidified powders  

SciTech Connect

This paper concerns the processing of Al-Cu alloys via a novel powder-metallurgy route. The specific technique used for powder processing involves the rapid solidification of coarse, molten droplets following impulse atomization. This produces a fine, homogeneous, dendritic microstructure within the alloy granules. Following consolidation via hot pressing, the microstructure consists mostly of an Al matrix with fine CuAl{sub 2} particles and partially recrystallized dendrites. Further heat treatment and/or thermomechanical processing completes the spheroidization process in the CuAl{sub 2} phase. Blending powders with different Cu has been used to make materials with a bimodal distribution of the local particle-volume-fraction content. The high temperature (773 K) strength of these materials decreases with increasing CuAl{sub 2} content. This can be explained using a flow model based on superplastic deformation, controlled by diffusion-accommodated sliding at Al grain boundaries. This mechanism may also explain the deformation-enhanced particle coarsening observed during channel-die forging operations.

Conlon, K.T.; Maire, E.; Wilkinson, D.S.; Henein, H.

2000-01-01

387

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

388

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

389

Under bump metallurgies for a wafer level CSP with eutectic Pb-Sn solder ball  

Microsoft Academic Search

Six types of under bump metallurgies (UBM) were investigated in terms of ball shear strength, fracture surface analysis, the adhesion of sputter-deposited metal to dielectric polymer, and microstructure observation to optimize the UBM of a wafer level chip size package (WLCSP) with Pb-Sn eutectic solder ball. UBMs investigated in this paper include Ti(0.2 ?m)\\/Cu(1.0 ?m), Ti(0.2 ?m)\\/Cu(5.0 ?m), Ti(0.2 ?m)\\/Ni(0.2

Soon-Jin Cho; Ji-Yon Kim; Myung-Geun Park; Ik-Sung Park; Heung-Sup Chun

2000-01-01

390

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

391

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

392

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

393

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

394

From Powders to Collapsing Soil\\/Living Quicksand: Discrete Modeling and Experiment  

Microsoft Academic Search

The discrete element method constitutes a general class of modeling techniques to simulate the microscopic behavior (i.e., at the particle scale) of granular\\/soil materials. We present a variant of the contact dynamics method, originally developed to model compact and dry systems with lasting contacts. This variant accounts for the cohesive nature of fine powders and soils. The attractive force plays

Dirk Kadau

2010-01-01

395

Near-net-shape forming of alumina powder under hot pressing and hot isostatic pressing  

Microsoft Academic Search

Densification and deformation of alumina powder under hot pressing and hot isostatic pressing were investigated. Finite element calculations were performed by implementing constitutive equations for grain growth, power law creep and diffusional creep in the user defined subroutine CREEP of ABAQUS. An alumina compact of valve head shape was produced under hot pressing and its forming process was predicted by

K. T. Kim; Y. S. Kwon; H. G. Kim

1997-01-01

396

Compact Polarimetry Potentials  

NASA Technical Reports Server (NTRS)

The goal of this study is to show the potential of a compact-pol SAR system for vegetation applications. Compact-pol concept has been suggested to minimize the system design while maximize the information and is declined as the ?/4, ?/2 and hybrid modes. In this paper, the applications such as biomass and vegetation height estimates are first presented, then, the equivalence between compact-pol data simulated from full-pol data and compact-pol data processed from raw data as such is shown. Finally, a calibration procedure using external targets is proposed.

Truong-Loi, My-Linh; Dubois-Fernandez, Pascale; Pottier, Eric

2011-01-01

397

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

398

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

399

Ceramic powder for sintering materials  

NASA Technical Reports Server (NTRS)

Surface activity of ceramic powders such as MgO and Al2O3, for use in sintering with sp. emphasis on their particle size, shape, particle size distribution, packing, and coexisting additives and impurities are reviewed.

Akiya, H.; Saito, A.

1984-01-01

400

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

401

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

402

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; Dav, Rajesh N

2015-01-30

403

Response to Thermal Exposure of Ball-Milled Cu-Mg/B2O3 Powder Blends  

NASA Astrophysics Data System (ADS)

The response to thermal exposure of ball-milled Cu-Mg/B2O3 powder blends was investigated in the current study to explore the potential of powder metallurgy route to produce Cu-B alloys. Cu-20Mg alloy powder was mixed with B2O3 and subsequently ball milled for 1 hour. Ball milling alone failed to establish a reaction between Cu-Mg compounds and B2O3. When the ball-milled powder blend was heated, however, B2O3 was reduced by CuMg2 <773 K (500 C). The Cu2Mg intermetallic phase, which has survived until 773 K (500 C), was involved in the reduction of the remaining B2O3 at still higher temperatures, while excess Mg reacted with B to produce MgB2 and MgB6 compounds. Cu-Mg alloy with predominantly the CuMg2 phase must be utilized to take advantage of the capacity of the CuMg2 (Cu-43 wt pct Mg) compound to reduce B2O3 at temperatures as low as 773 K (500 C). Once the Cu-43Mg alloy powder is mixed with B2O3 and the powder blend thus obtained is ball milled and subsequently heated at 500 C, B2O3 is readily reduced by CuMg2 to yield Cu, B, and MgO. The latter can be easily removed from the powder blend by acid leaching.

Birol, Yucel

2013-08-01

404

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

405

Method for Production of Powders  

NASA Technical Reports Server (NTRS)

Apparatus and method are disclosed for producing oxides of metals and of metal alloys. The metal or alloy is placed in an oxygen atmosphere in a combustion chamber and ignited. Products of the combustion include one or more oxides of the metal or alloy in powdered form. In one embodiment of the invention a feeder is provided whereby material to be oxidized by combustion can be achieved into a combustion chamber continuously. A product remover receives the powder product of the combustion.

Stoltzfus, Joel M. (Inventor); Sircar, Subhasish (Inventor)

1997-01-01

406

Neutron detectors comprising boron powder  

DOEpatents

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

407

Zirconia ceramics from coprecipitated powders  

Microsoft Academic Search

The possibility was explored of making dense and strong partly stabilized zirconia (PSZ)-based ceramic materials from coprecipitated\\u000a zirconium and yttrium hydroxide powders of both factory and laboratory preparation. The effect of dry and wet grinding, powder\\u000a burning, cold isostatic pressure (CIP) at?0.8 GPa, and sintering at ?1600?C on the physicochemical properties of the material\\u000a was investigated. It was found that

I. Yu. Prokhorov

1997-01-01

408

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

409

Compact Groups of Galaxies  

Microsoft Academic Search

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

Paul Hickson

1997-01-01

410

Compact Propositional Gdel 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

411

Branching to maximal compact  

E-print Network

's thm and alg geometry Zuckerman's thm From K to G and back again Summary Branching to maximal compact classically Helgason's thm and alg geometry Zuckerman's thm From K to G and back again Summary Outline the branching law: Zuckerman's theorem Relating representations of K and G #12;Branching to maximal compact

Vogan, David

412

SOIL COMPACTION MANAGEMENT  

Technology Transfer Automated Retrieval System (TEKTRAN)

During temporary droughts that often limit agricultural production, soil compaction can hinder plant roots from reaching depths of soil where moisture is available. Many fields exhibit various degrees of soil compaction, resulting from variable soil types and past tillage and traffic practices. Va...

413

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...

414

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

415

Environmental legacy of copper metallurgy and mongol silver smelting recorded in yunnan lake sediments.  

PubMed

Geochemical measurements on well-dated sediment cores from Lake Er (Erhai) are used to determine the timing of changes in metal concentrations over 4500 years in Yunnan, a borderland region in southwestern China noted for rich mineral deposits but with inadequately documented metallurgical history. Our findings add new insight into the impacts and environmental legacy of human exploitation of metal resources in Yunnan history. We observe an increase in copper at 1500 BC resulting from atmospheric emissions associated with metallurgy. These data clarify the chronological issues related to links between the onset of Yunnan metallurgy and the advent of bronze technology in adjacent Southeast Asia, subjects that have been debated for nearly half a century. We also observe an increase from 1100 to 1300 AD in a number of heavy metals including lead, silver, zinc, and cadmium from atmospheric emissions associated with silver smelting. Culminating during the rule of the Mongols, known as the Yuan Dynasty (1271-1368 AD), these metal concentrations approach levels three to four times higher than those from industrialized mining activity occurring within the catchment today. Notably, the concentrations of lead approach levels at which harmful effects may be observed in aquatic organisms. The persistence of this lead pollution over time created an environmental legacy that likely contributes to known issues in modern day sediment quality. We demonstrate that historic metallurgical production in Yunnan can cause substantial impacts on the sediment quality of lake systems, similar to other paleolimnological findings around the globe. PMID:25685905

Hillman, Aubrey L; Abbott, Mark B; Yu, JunQing; Bain, Daniel J; Chiou-Peng, TzeHuey

2015-03-17

416

An Experimental Evaluation of the Gerdemann-Jablonski Compaction Equation  

NASA Astrophysics Data System (ADS)

This paper reports on an attempt to independently evaluate the validity and applicability of a new compaction equation recently presented by Gerdemann and Jablonski [Metallurgical and Materials Transactions A, 42 (2011) 1325-1333] using experimental data. Furthermore, the rationality of Gerdemann and Jablonski's interpretation of the equation parameters is examined. The results are discussed in terms of the comparative evaluation of four different titanium powders (sponge Ti, CP TiH2, Grade 2 CP Ti, and TiH2-SS316L nanocomposite blend prepared by high energy milling) cold pressed in die to compaction pressures of up to 1300 MPa.

Machaka, Ronald; Chikwanda, Hilda K.

2015-02-01

417

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

418

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

419

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

420

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

421

30 CFR 57.6901 - Black powder.  

Code of Federal Regulations, 2014 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...

2014-07-01

422

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

423

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

424

30 CFR 56.6901 - Black powder.  

Code of Federal Regulations, 2014 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...

2014-07-01

425

Ceramic oxide powders and the formation thereof  

DOEpatents

Ceramic oxide powders and a method for their preparation. Ceramic oxide powders are obtained using a flame process whereby two or more precursors of ceramic oxides are introduced into a counterflow diffusion flame burner wherein said precursors are converted into ceramic oxide powders. The morphology, particle size, and crystalline form of the ceramic oxide powders are determined by process conditions. 14 figures.

Katz, J.L.; Chenghung Hung.

1993-12-07

426

FABRICATION BEHAVIOR OF SOME URANIUM DIOXIDE POWDERS  

Microsoft Academic Search

The physical characteristics of uranium dioxide powders depend not only ; upon how they are prepared, but also upon the treatment of the powders prior to ; fabrication. Preliminary attempts to produce high-density sintered UO ; bodies demonstrated a wide range of sinterability among UO powders having ; different physical characteristics. Sintered densities of various UO ; powders varied from

D. R. Stenquist; R. J. Anicetti

1957-01-01

427

Edge-restraint deformation processing of aluminides and other powders  

NASA Technical Reports Server (NTRS)

The novel, 'edge-restraint rolling' method has been developed in order to facilitate the thickness reduction of brittle, high strength alloys to the degree of thin plates or sheets, by first hot-compacting the prealloyed powders into billets and conducting the thickness reduction in a series of reheats and roll passes. Attention is presently given to the cases of equiatomic aluminide FeAl, (Ni,Fe)3Al, and an Al-Fe alloy. The flat-rolled products thus obtained may lead to the development of components not otherwise formable for powerplant and other aerospace applications.

Bhattacharyya, S.

1986-01-01

428

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

429

Influence of Gas Type on the Thermal Efficiency of Microwave Plasmas for the Sintering of Metal Powders  

Microsoft Academic Search

Microwave plasmas have enormous potential as a rapid and energy efficient sintering technology. This paper evaluates the influence\\u000a of both plasma atmosphere and metal powder type on the sintering temperatures achieved and the properties of the sintered\\u000a powder metal compacts. The sintering is carried out using a 2.45GHz microwave-plasma process called rapid discharge sintering\\u000a (RDS). The sintering of three types

Aidan Breen; Vladimir Milosavljevi?; Denis P. Dowling

430

Flake tantalum powder for manufacturing electrolytic capacitors  

Microsoft Academic Search

The FTP200 flake tantalum powder was introduced. The microstructures of the powder with leaf-like primary particles having an average flakiness of 2 to 20 and porous agglomerated particles were observed. The chemical composition, physical properties, and electrical properties of the FTP200 powder were compared with those of the FTW300 nodular powder. The FTP200 powder is more sinter-resistant, and the surface

Jilin HE; Guoqi YANG; Luntao PAN; Hongdong LIU; Xifang BAO

2008-01-01

431

Preliminary characterization of interlayer for Be/Cu sintered compacts  

SciTech Connect

At present, beryllium is under consideration as a main candidate material for plasma facing components of ITER, because of its many advantages such as low Z, high thermal conductivity, low tritium retention, low activation and so on. Among the different divertor design options, the duplex structure where the beryllium armor is bonded with heat sink structural materials (DS-copper, Cu-Cr-Zr and so on) is under consideration. And plasma facing components will be exposed to high heat load and high neutron flux generated by the plasma. Therefore, it is necessary to develop the reliable bonding technologies between beryllium and heat sink structural materials in order to fabricate plasma facing components which can resist those. Then, we started the bonding technology development of beryllium and copper alloy with FGM (functional gradient material) in order to reduce thermal stress due to the difference of thermal expansion between beryllium and copper alloy. As the interlayers for FGM, eleven kinds of sintered compacts in which the mixing ratio of beryllium powder and oxygen free copper powder is different, were fabricated by the hot press/HIP method. The dimension of each compact is 8mm in diameter, 2mm in thickness. Then, thermal diffusivity and specific heat of these compacts were measured by laser flash method, and thermal conductivity was calculated from those values. From metalographical observation, it became clear that the sintered compacts of mixture of beryllium powder and copper powder contain residual beryllium, copper and two kinds of intermetallic compounds, Be{sub 2}Cu({delta}) and BeCu({gamma}). From the results of thermal characterization, thermal diffusivity of interlayers increased with increase of copper containing ratio. And, specific heat gradually decreased with increase of copper containing ratio.

Sakamoto, N.; Kawamura, H. [Oarai Research Establishment, Ibaraki-ken (Japan)

1995-09-01

432

Spatio-temporal dynamics behind the shock front from compacted metal nanopowders.  

PubMed

Laser ablated shock waves from compacted metal nanoenergetic powders of Aluminum (Al), Nickel coated Aluminum (Ni-Al) was characterized using shadowgraphy technique and compared with that from Boron Potassium Nitrate (BKN), Ammonium Perchlorate (AP) and Potassium Bromide (KBr) powders. Ablation is created by focused second harmonic (532 nm, 7 ns) of Nd:YAG laser. Time resolved shadowgraphs of propagating shock front and contact front revealed dynamics and the precise time of energy release of materials under extreme ablative pressures. Among the different compacted materials studied, Al nanopowders have maximum shock velocity and pressure behind the shock front compared to others. PMID:24922235

Leela, Ch; Venkateshwarlu, P; Singh, Raja V; Verma, Pankaj; Kiran, P Prem

2014-03-10

433

Chemical Reactions in the Processing of Mosi2 + Carbon Compacts  

NASA Technical Reports Server (NTRS)

Hot-pressing of MoSi2 powders with carbon at high temperatures reduces the siliceous grain boundary phase in the resultant compact. The chemical reactions in this process were examined using the Knudsen cell technique. A 2.3 wt pct oxygen MoSi2 powder and a 0.59 wt pct oxygen MoSi2 powder, both with additions of 2 wt pct carbon, were examined. The reduction of the siliceous grain boundary phase was examined at 1350 K and the resultant P(SiO)/P(CO) ratios interpreted in terms of the SiO(g) and CO(g) isobars on the Si-C-O predominance diagram. The MoSi2 + carbon mixtures were then heated at the hot-pressing temperature of 2100 K. Large weight losses were observed and could be correlated with the formation of a low-melting eutectic and the formation and vaporization of SiC.

Jacobson, Nathan S.; Lee, Kang N.; Maloy, Stuart A.; Heuer, Arthur H.

1993-01-01

434

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 Khler, 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

435

Compact Conformal Manifolds  

E-print Network

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 Kahler, 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 N=2->N=1 breaking deformations of strongly interacting N=2 SCFTs. In many cases, our prescription reduces the construction of such spaces to a study of the N=2 chiral ring. We also give an algorithm for constructing more general compact spaces of SCFTs.

Matthew Buican; Takahiro Nishinaka

2014-11-14

436

Compact microchannel system  

DOEpatents

The present invention provides compact geometries for the layout of microchannel columns through the use of turns and straight channel segments. These compact geometries permit the use of long separation or reaction columns on a small microchannel substrate or, equivalently, permit columns of a fixed length to occupy a smaller substrate area. The new geometries are based in part on mathematical analyses that provide the minimum turn radius for which column performance in not degraded. In particular, we find that straight channel segments of sufficient length reduce the required minimum turn radius, enabling compact channel layout when turns and straight segments are combined. The compact geometries are obtained by using turns and straight segments in overlapped or nested arrangements to form pleated or coiled columns.

Griffiths, Stewart

2003-09-30

437

Compact turbidity meter  

NASA Technical Reports Server (NTRS)

Proposed monitor that detects back-reflected infrared radiation makes in situ turbidity measurements of lakes, streams, and other bodies of water. Monitor is compact, works well in daylight as at night, and is easily operated in rough seas.

Hirschberg, J. G.

1979-01-01

438

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

439

Synthesis of nanosized hydroxyapatite powders.  

PubMed

Hydroxyapatite powder was mechanochemically synthesized from calcium pyrophosphate (Ca2P2O7) and calcium carbonate (CaCO3) using a solid-state reaction. The two powders were mixed in distilled water, milled for 8 hours, dried and calcined at 1100 degrees C for 1 hour. The phase(s) formed was analyzed by x-ray diffraction (XRD). It was found that hydroxyapatite was not the only one formed. This result will be used as the starting point to produce a single-phase hydroxyapatite in terms of excess hydroxyl group in a mechanochemical reaction. PMID:15468867

Zarina, O; Radzali, O

2004-05-01

440

Friction Consolidation of MA956 powder  

NASA Astrophysics Data System (ADS)

The applicability of Friction Consolidation (FC) to process an oxide dispersion strengthened (ODS) steel was studied to tackle the downsides of the conventional processing route (high complexity, extremely high raw material final cost). In this work, MA956 ODS powders have been consolidated through the FC process and small compacts of low porosity have been achieved with the desired oxide dispersion. The friction-consolidated sample shows a range of grain sizes when measuring at different locations within the cross section of the sample, and the values were all finer than those of a conventionally-processed sample. With regard to shape, grains in the friction-consolidated sample show an equiaxed cross section. Three particle families were observed: Y-Al-O, Al-O and Ti(C, N). The Y-Al-O and the Al-O were observed in both the conventionally- and the friction-consolidated sample. This result points out the ability to achieve the precipitation of the Y-Al-O by FC. The Ti(C, N) particles were only observed in the conventionally processed sample. The transmission electron microscopy images showed regions with smaller particles on the friction-consolidated sample. However, due to the extremely localized nature of the measurement, more data should be generated and analyzed to make this observation more statistically reliable.

Catalini, David; Kaoumi, Djamel; Reynolds, Anthony P.; Grant, Glenn J.

2013-11-01

441

Energy-Saving Sintering of Electrically Conductive Powders by Modified Pulsed Electric Current Heating Using an Electrically Nonconductive Die  

NASA Astrophysics Data System (ADS)

Sintering of Cu and thermoelectric Ca3Co4O9 was tried using a modified pulsed electric current sintering (PECS) process, where an electrically nonconductive die was used instead of a conventional graphite die. The pulsed electric current flowed through graphite punches and sample powder, which caused the Joule heating of the powder compact itself, resulting in sintering under smaller power consumption. Especially for the Ca3Co4O9 powder, densification during sintering was also accelerated by this modified PECS process.

Ito, Mikio; Kawahara, Kenta; Araki, Keita

2014-04-01

442

The alloy with a memory, 55-Nitinol: Its physical metallurgy, properties, and applications  

NASA Technical Reports Server (NTRS)

A series of nickel titanium alloys (55-Nitinol), which are unique in that they possess a shape memory, are described. Components made of these materials that are altered in their shapes by deformation under proper conditions return to predetermined shapes when they are heated to the proper temperature range. The shape memory, together with the force exerted and the ability of the material to do mechanical work as it returns to its predetermined shape, suggest a wide variety of industrial applications for the alloy. Also included are discussions of the physical metallurgy and the mechanical, physical, and chemical properties of 55-Nitinol; procedures for melting and processing the material into useful shapes; and a summary of applications.

Jackson, C. M.; Wagner, H. J.; Wasilewski, R. J.

1972-01-01

443

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

444

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; Gonalves, S I V; De Geest, B G; Remon, J P; Vervaet, C

2008-03-01

445

Triboelectric charging of polymer powders in fluidization and transport processes  

Microsoft Academic Search

Steady flow of powder at a desired rate is a necessity for controlling thickness and uniformity of the deposited powder layer in electrostatic spray painting. In most powder coating applications, the polymer powder is fluidized to transport the powder to the spray gun using a powder pump. The powder delivery tube is often long; sometimes in excess of 10 m.

J. R. Mountaint; D. L. Wankum; M. K. Mazumder; T. Chasser; P. Pettit

1997-01-01

446

Semi Compactness in Multiset Topology  

E-print Network

In this paper, we introduce and study the concepts of semi open SOM) and semi closed (SCM) M-sets in multiset topological spaces.With this generalization of the notions of open and closed sets in M-topology, we generalize the concept of compactness in M-topology as semi compactness. Further semi compactness is generalized as semi whole compactness, semi partial whole compactness and semi full compactness. Some characterizations of these compact spaces are studied in the setting of multiset theory. In each step, several remarks with proper justifications are provided taking the well existing theories of general topology as the base of our study.

J. Mahanta; D. Das

2014-11-21

447

POWDER COATINGS: A TECHNOLOGY REVIEW  

EPA Science Inventory

In 1995, surface coatings accounted for nearly 2.55 million Mg of volatile organic compound (VOC) emissions nationally, which is more than 12% of VOC emissions from all sources. In recent years, powder coatings have been steadily gaining popularity as an alternative to solvent-bo...

448

Pharmaceutically Engineering Powders Using FHMG  

Microsoft Academic Search

Fluidized hot melt granulation (FHMG) is an innovative granulation process that has distinct advantages over techniques that are typically used in the pharmaceutical industry for powder agglomeration and mixing. The aim of this research was to investigate process and formulation parameters that affect FHMG, in a pharmaceutical context, using Lutrol F68 (copolymer of polyoxyethylene-polyoxypropylene) as a meltable binder with inert

G. Walker; S. Bell; M. Vann; H. Zhai; D. Jones; G. Andrews

2007-01-01

449

Two-dimensional distribution of carbon nanotubes in copper flake powders  

NASA Astrophysics Data System (ADS)

We report an approach of flake powder metallurgy to the uniform, two-dimensional (2D) distribution of carbon nanotubes (CNTs) in Cu flake powders. It consists of the preparation of Cu flakes by ball milling in an imidazoline derivative (IMD) aqueous solution, surface modification of Cu flakes with polyvinyl alcohol (PVA) hydrosol and adsorption of CNTs from a CNT aqueous suspension. During ball milling, a hydrophobic monolayer of IMD is adsorbed on the surface of the Cu flakes, on top of which a hydrophilic PVA film is adsorbed subsequently. This PVA film could further interact with the carboxyl-group functionalized CNTs and act to lock the CNTs onto the surfaces of the Cu flakes. The CNT volume fraction is controlled easily by adjusting the concentration/volume of CNT aqueous suspension and Cu flake thickness. The as-prepared CNT/Cu composite flakes will serve as suitable building blocks for the self-assembly of CNT/Cu laminated composites that enable the full potential of 2D distributed CNTs to achieve high thermal conductivity.

Tan, Zhanqiu; Li, Zhiqiang; Fan, Genlian; Li, Wenhuan; Liu, Qinglei; Zhang, Wang; Zhang, Di

2011-06-01

450

Two-dimensional distribution of carbon nanotubes in copper flake powders.  

PubMed

We report an approach of flake powder metallurgy to the uniform, two-dimensional (2D) distribution of carbon nanotubes (CNTs) in Cu flake powders. It consists of the preparation of Cu flakes by ball milling in an imidazoline derivative (IMD) aqueous solution, surface modification of Cu flakes with polyvinyl alcohol (PVA) hydrosol and adsorption of CNTs from a CNT aqueous suspension. During ball milling, a hydrophobic monolayer of IMD is adsorbed on the surface of the Cu flakes, on top of which a hydrophilic PVA film is adsorbed subsequently. This PVA film could further interact with the carboxyl-group functionalized CNTs and act to lock the CNTs onto the surfaces of the Cu flakes. The CNT volume fraction is controlled easily by adjusting the concentration/volume of CNT aqueous suspension and Cu flake thickness. The as-prepared CNT/Cu composite flakes will serve as suitable building blocks for the self-assembly of CNT/Cu laminated composites that enable the full potential of 2D distributed CNTs to achieve high thermal conductivity. PMID:21454945

Tan, Zhanqiu; Li, Zhiqiang; Fan, Genlian; Li, Wenhuan; Liu, Qinglei; Zhang, Wang; Zhang, Di

2011-06-01

451

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/cm 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

452

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

453

"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

454

Powder functionality test: a methodology for rheological and mechanical characterization.  

PubMed

In most pharmaceutical formulations, the part of the excipients, in quantity and number, is larger than that of active principles, justifying particular attention to their characteristics to ensure quality, efficacy, and reproducibility of final forms. Whereas chemical specifications are described in Pharmacopeias, physical characteristics, up to now, have not been sufficiently considered. Nevertheless, there is a need for tests to objectively compare technological performances of products and justify composition of medicinal products. The powder functionality test described in this article is based on the analysis of the global behavior of materials under pressure. The powder compression is performed using an instrumented uniaxial press, Lloyd 6000R, and a compression cell of 1 cm3 in volume, allowing a complete and early characterization with a few grams of material. Indices characterizing packing, densification energies, energetic yields, and deformation mode of the particles are proposed from the analysis of compression cycles. Cohesion and energy of rupture are deduced from the diametral rupture cycles of the compacts. Application of this methodology to supplied celluloses has shown better flow properties of microcrystalline celluloses due to their higher bulk density and particle size. The energy fraction lost as frictions is very important and independent of the type of celluloses, whereas elastic energy is higher for powdered celluloses P100 and G250. Finally the efficacy to convert compaction energy into cohesion is higher for products with a small degree of polymerization, i.e., microcrystalline celluloses, except A301 and A302, which also are distinguished by their low porosity. PMID:15926682

Viana, Marylne; Ribet, Jrome; Rodriguez, Fernand; Chulia, Dominique

2005-01-01

455

Physically detached 'compact groups'  

NASA Technical Reports Server (NTRS)

A small fraction of galaxies appear to reside in dense compact groups, whose inferred crossing times are much shorter than a Hubble time. These short crossing times have led to considerable disagreement among researchers attempting to deduce the dynamical state of these systems. In this paper, we suggest that many of the observed groups are not physically bound but are chance projections of galaxies well separated along the line of sight. Unlike earlier similar proposals, ours does not require that the galaxies in the compact group be members of a more diffuse, but physically bound entity. The probability of physically separated galaxies projecting into an apparent compact group is nonnegligible if most galaxies are distributed in thin filaments. We illustrate this general point with a specific example: a simulation of a cold dark matter universe, in which hydrodynamic effects are included to identify galaxies. The simulated galaxy distribution is filamentary and end-on views of these filaments produce apparent galaxy associations that have sizes and velocity dispersions similar to those of observed compact groups. The frequency of such projections is sufficient, in principle, to explain the observed space density of groups in the Hickson catalog. We discuss the implications of our proposal for the formation and evolution of groups and elliptical galaxies. The proposal can be tested by using redshift-independent distance estimators to measure the line-of-sight spatial extent of nearby compact groups.

Hernquist, Lars; Katz, Neal; Weinberg, David H.

1995-01-01

456

ER Physician Raises Concerns about Powdered Caffeine  

MedlinePLUS

... experts. The main difference between powdered and liquid alcohol is its packaging. The powder may be more convenient to pack and carry, but it's not a concentrated form of alcohol. Critics warn however, young people may be tempted ...

457

21 CFR 73.2646 - Bronze powder.  

Code of Federal Regulations, 2011 CFR

...OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics 73.2646 Bronze powder. (a) Identity...Bronze powder may be safely used in coloring cosmetics generally, including cosmetics intended for use in the area of the eye,...

2011-04-01

458

21 CFR 73.2646 - Bronze powder.  

Code of Federal Regulations, 2010 CFR

...OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics 73.2646 Bronze powder. (a) Identity...Bronze powder may be safely used in coloring cosmetics generally, including cosmetics intended for use in the area of the eye,...

2010-04-01

459

21 CFR 73.2647 - Copper powder.  

Code of Federal Regulations, 2014 CFR

...OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics 73.2647 Copper powder. (a) Identity...Copper powder may be safely used in coloring cosmetics generally, including cosmetics intended for use in the area of the eye,...

2014-04-01

460

21 CFR 73.2647 - Copper powder.  

Code of Federal Regulations, 2013 CFR

...OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics 73.2647 Copper powder. (a) Identity...Copper powder may be safely used in coloring cosmetics generally, including cosmetics intended for use in the area of the eye,...

2013-04-01

461

21 CFR 73.2646 - Bronze powder.  

Code of Federal Regulations, 2013 CFR

...OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics 73.2646 Bronze powder. (a) Identity...Bronze powder may be safely used in coloring cosmetics generally, including cosmetics intended for use in the area of the eye,...

2013-04-01

462

21 CFR 73.2646 - Bronze powder.  

Code of Federal Regulations, 2014 CFR

...OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics 73.2646 Bronze powder. (a) Identity...Bronze powder may be safely used in coloring cosmetics generally, including cosmetics intended for use in the area of the eye,...