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1

Advanced NDE Techniques for Powder Metal Components.  

National Technical Information Service (NTIS)

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 no...

P. Martin J. Haskins G. Thomas K. Dolan

2003-01-01

2

Pyrolytic preparations of ceramic powders by a spray calcination technique  

Microsoft Academic Search

A laboratory-scale facility for pyrolytic preparation of powders used in ceramic materials fabrication is presented. It is shown through examples that application of the technique described allows very homogeneous powders to be prepared which, by conventional techniques, can be prepared either with great difficulty or practically not at all. A typical application in the system ZrO2-Y2O3-Al2O3 is shown. From experimental

D. Vollath

1990-01-01

3

Nanosized bismuth ferrite powder prepared through sonochemical and microemulsion techniques  

Microsoft Academic Search

Two processing routes, namely sonochemical and microemulsion have been exploited to prepare bismuth ferrite powders. Phase pure nanosized BiFeO3 powders are prepared by sonochemical and microemulsion techniques in the temperature range of 400C and at 500C which is much lower than that of the conventional preparation methods. The XRD obtained from both cases was likely to be pure bismuth ferrite.

Nandini Das; Ranabrata Majumdar; A. Sen; H. S. Maiti

2007-01-01

4

Powder agglomeration patterns at acoustic driving observed by sonoluminescence technique  

NASA Astrophysics Data System (ADS)

A sonoluminescence (SL) technique gives a sensitive probe to detect spatial agglomeration patterns produced in powder mixtures subjected to acoustically driven plate. Studies of the surface-integrated SL intensity with increasing driving amplitude yield data about variations of the packing density on the surface of vibrating powders. Imaging of spatial distributions of the SL intensity enables direct measurement of the size of agglomeration patterns. The size of the patterns is found to be ~102 ?m in a 3-?m-sized powder at a driving frequency of about 4 MHz. The distribution of the average sonoluminescence intensity across the pattern is attributed to the density gradient while rapid variations in the SL intensity across the pattern are suggested to give the particle velocity distribution within the pattern. The temporal changes of the SL intensity can be used to study time evolutions of dense powder arrangements.

Korotchenkov, O. A.; Goto, T.

1999-01-01

5

Toward a Process-Based Framework for Classifying Personality Tests: Comment on Meyer and Kurtz (2006)  

Microsoft Academic Search

Meyer and Kurtz (2006) argued that the longstanding psychological test labels objective and projective have outlived their usefulness, and invited further work focusing on alternative terms for these measures. This Comment describes a framework for classifying personality tests based on the psychological processes that occur as people respond to test stimuli. Because an attribution process is involved in responding to

Robert F. Bornstein

2007-01-01

6

Communicating with the Dead: The Evidence Ignored Why Paul Kurtz is Wrong  

Microsoft Academic Search

A far-ranging attack on the evidence for the paranormal in general, and the case for post-mortem survival of intelligence in particular, was published in 2000 by Professor Paul Kurtz in the Skeptical Inquirer , organ of the Committee for the Scientific Investigation of Claims of the Paranormal. Reluctance of its Editor to fulfil an undertaking to publish a response has

MONTAGUE KEEN

7

The Coating of Aluminum with Plastics by the Fluidized-Bed and Electrostatic Powder Techniques.  

National Technical Information Service (NTIS)

The paper describes plastic powder coating of metal objects, particularly aluminum, by the fluidized-bed and electrostatic powder techniques. It points out the importance of control of process parameters such as preheat and postheat temperatures and dwell...

A. H. Landrock

1968-01-01

8

Ti-B-C composite coating produced by electrothermally exploded powder-spray technique  

Microsoft Academic Search

Composite coatings of a Ti-B-C system were reactively produced by the electrothermally exploded powderspray (ELTEPS) technique.\\u000a First, the electrical characteristics of the ELTEPS system were determined. The starting powder of the coatings was titanium\\u000a powder mixed with boron carbide powder. This powder was prepared for production of Ti-B-C composite coatings on substrates\\u000a using the ELTEPS technique. The coatings obtained were

Fumihiro Kikkawa; Hideki Tamura; Ken-Ich Kondo

2006-01-01

9

Influence of raw powder preparation routes on properties of hydroxyapatite fabricated by 3D printing technique  

Microsoft Academic Search

A comparison between two routes of raw powder preparation, namely spray drying and grinding, for 3D printing of hydroxyapatite was carried out. Hydroxyapatite particles prepared by the spray drying technique were spherical in shape whereas the grinding route gave irregular-shaped agglomerates. Spray-dried powders had higher tap density than milled powders, however milled powders yielded 3DP specimens with greater green density

J. Suwanprateeb; R. Sanngam; T. Panyathanmaporn

2010-01-01

10

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

National Technical Information Service (NTIS)

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 radiog...

T. Garino M. Mahoney M. Readey K. Ewsuk J. Gieske

1995-01-01

11

The preparation of AI 2 O 3 \\/Ni composites by a powder coating technique  

Microsoft Academic Search

In the present study, nickel particles are coated onto the surface of alumina powder by an impregnation technique. The densification behaviour and the microstructural evolution of the nickel coated alumina powder during sintering are investigated. The strength and the toughness of the resulting Al2O3\\/Ni composites are determined. As the nickel content is less than 13 vol%, fully dense composites can

W. H. Tuan; H. H. Wu; T. J. Yang

1995-01-01

12

A sol-powder coating technique for fabrication of yttria stabilised zirconia  

Microsoft Academic Search

Yttria stabilised zirconia has been prepared using a simple sol-powder coating technique. The polymeric yttria sol, which was prepared using 1,3 propanediol as a network modifier, was homogeneously mixed with nanocrystalline zirconia powder and it showed a dual function: as a binder which promoted densification and a phase modifier which stabilised zirconia in the tetragonal and cubic phases. Thermal analysis

Darunee. Wattanasiriwech; Suthee Wattanasiriwech; Ron Stevens

2006-01-01

13

Nano powders, components and coatings by plasma technique  

Microsoft Academic Search

Ultra fine and nanometer powders and a method of producing same are provided, preferably refractory metal and ceramic nanopowders. When certain precursors are injected into the plasma flame in a reactor chamber, the materials are heated, melted and vaporized and the chemical reaction is induced in the vapor phase. The vapor phase is quenched rapidly to solid phase to yield

Timothy N. McKechnie; Leo V. M. Antony; Scott ODell; Chris Power; Terry Tabor

2009-01-01

14

Needle-Free Delivery of Powdered Protein Vaccines: A New and Rapidly Developing Technique  

Microsoft Academic Search

Skin is an attractive tissue for vaccine delivery. Recently, interest has focused on dry powder injectors for needle-free\\u000a vaccination. This review summarizes the current knowledge on this innovative application technique.

Andreas S. Ziegler

2008-01-01

15

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

Microsoft Academic Search

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

Terry Garino; Mike Mahoney; Mike Readey; Kevin Ewsuk; John Gieske; Gerry Stoker; Shermann Min

1995-01-01

16

Sintering of MulliteZirconia Composite Powder Prepared by Ultrasonic Spray Pyrolysis Technique  

Microsoft Academic Search

Sinterabilities of mullite (3Al2O32SiO2zirconia (ZrO2)composite powders prepared by ultrasonic spray pyrolysis techniques (USPTs) were examined. Starting mullite powders containing ~18.5 mol% (~15.0 vol%) of zirconia (ZrO2) were prepared by single-nozzle (SN) and double-nozzle (DN) USPT. In SN-USPT, the composite powder was prepared by spray pyrolysis of a waterethanol solution in an Al(NO3)3Si(OC2H5)4ZrOCl2YCl3 system at 900C, using one ultrasonic vibrator. In

Kiyoshi Itatani; Takashi Abiko; Mamoru Aizawa; F. Scott Howell; Akira Kishioka

1998-01-01

17

Comparison of particle sizing techniques in the case of inhalation dry powders.  

PubMed

The objectives of this work were (i) to validate electrical zone sensing and laser diffraction for the analysis of primary particle size in the case of inhalation dry powders and (ii) to study the influence of the aggregation state of the powder on the sizing techniques. Free-flowing dry powders were prepared by spray-drying with a combination of albumin, lactose, and dipalmitoylphosphatidylcholine. The replacement of lactose by mannitol, the removal of albumin, and the atomization at high relative humidity all increased powder cohesion. Automated measurements were compared with primary particle sizes collected by light and electron microscopy. The mass mode obtained by electrical zone sensing and the mass median diameter measured by laser diffraction following dispersion with compressed air at a pressure of 3 bar or following suspension in water and ultrasonic dispersion at a power of 60 W for 30 s each provided primary particle sizes close to microscopy measurements. However, these conditions only applied in the case of slightly to moderately aggregated powders. For strongly agglomerated powders, an exact measurement of the size was only collected by laser diffraction in the wet state combined with ultrasonic dispersion. Our study underlies how measurement of primary particle size highly depends on both powder material and proper particle dispersion. PMID:11745762

Bosquillon, C; Lombry, C; Preat, V; Vanbever, R

2001-12-01

18

Determination of surface free energy of interactive dry powder liposome formulations using capillary penetration technique.  

PubMed

The surface free energy of interactive dry powder formulations consisting of varying ratios of lactose plus liposomal ciprofloxacin were determined using capillary penetration technique. Powder is produced by jet-milling after mixing with lyophilized liposomal ciprofloxacin with inhalation grade lactose powder (Pharmatose 325M). Measurement of the weight gained during intrusion of different liquids in a packed column of powder is combined with dynamic considerations to give the surface free energy, gamma(sv). Confidence in methodology was gained by determining gamma(sv) for PMMA microspheres and comparing to literature values. Values of gamma(sv) are then obtained for unmilled Pharmatose 325M powder (gamma(sv)=54.2 mJ m(-2)), milled Pharmatose 325M (gamma(sv)=54.2 mJ m(-2)) and lipid:lactose formulations with weight ratios of 1:5, 1:10 and 1:20. All the powder liposomal formulations are found to have the same gamma(sv)=48.0 mJ m(-2), suggesting that adhesive forces in the three interactive powders should be similar barring any confounding roughness effects. PMID:11451657

Desai, T R.; Li, D; Finlay, W H.; Wong, J P.

2001-10-01

19

Measurement techniques in dry-powdered processing of spent nuclear fuels.  

SciTech Connect

High-performance liquid chromatography (HPLC) with inductively coupled plasma mass spectrometry (ICPMS) detection, {alpha}-spectrometry ({alpha}-S), and {gamma}-spectrometry ({gamma}-S) were used for the determination of nuclide content in five samples excised from a high-burnup fuel rod taken from a pressurized water reactor (PWR). The samples were prepared for analysis by dissolution of dry-powdered samples. The measurement techniques required no separation of the plutonium, uranium, and fission products. The sample preparation and analysis techniques showed promise for in-line analysis of highly-irradiated spent fuels in a dry-powdered process. The analytical results allowed the determination of fuel burnup based on {sup 148}Nd, Pu, and U content. A goal of this effort is to develop the HPLC-ICPMS method for direct fissile material accountancy in the dry-powdered processing of spent nuclear fuel.

Bowers, D. L.; Hong, J.-S.; Kim, H.-D.; Persiani, P. J.; Wolf, S. F.

1999-07-21

20

Developing a quantitative extraction technique for determining the organic additives in smokeless handgun powder.  

PubMed

Compositional analysis of the organic additives in smokeless handgun powder can provide forensic information to associate known and questioned samples. A reliable method for the quantitative extraction of smokeless powder additives would strengthen these measurements. To achieve quantitative recovery, both supercritical fluid extraction (SFE) and ultrasonic solvent extraction (USE) were evaluated as candidate techniques. Following a detailed evaluation of the solvent choice, the recovery of spiked additive compounds, and the effect of the powder matrix, a reliable USE technique was developed. When quantitative USE recovery of the target analytes, nitroglycerin (NG), diphenylamine (DPA), and ethyl centralite (EC), is coupled with additive measurement by micellar capillary electrophoresis (CE), compositional information can be obtained in less than 1 h. PMID:11451060

Reardon, M R; MacCrehan, W A

2001-07-01

21

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

22

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

NASA Astrophysics Data System (ADS)

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, Terry; Mahoney, Mike; Readey, Mike; Ewsuk, Kevin; Gieske, John; Stoker, Gerry; Min, Shermann

23

Preparation of WCu nano-composite powder using a freeze-drying technique  

Microsoft Academic Search

WCu composite materials have been widely used in heat sink apparatus and as electronic packaging materials. The preparation of the materials, especially the synthesis of WCu nanopowder, is a subject much more researches on. This paper focuses on the synthesis of WCu composite nanopowder using the freeze-drying technique, an environment-friendly and advanced technique for powder manufacturing. The process involved mixing

Xiaoli Xi; Xiangyang Xu; Zuoren Nie; Shan He; Wei Wang; Jie Yi; Zuo Tieyong

2010-01-01

24

Characterization of hydroxyapatite powders prepared by ultrasonic spray-pyrolysis technique  

Microsoft Academic Search

The hydroxyapatite (HAp) powder was prepared by the ultrasonic spray-pyrolysis technique; the characterization of the resulting powders was performed. Five kinds of the starting solutions with the Ca\\/P ratio of 1.67 were prepared by mixing Ca(NO3)2, (NH4)2HPO4 and HNO3; the concentrations of Ca2+ and PO43- were in the ranges of 0.10 to 0.90 mol??dm-3 and 0.06 to 0.54 mol??dm-3, respectively.

M. Aizawa; T. Hanazawa; K. Itatani; F. S. Howell; A. Kishioka

1999-01-01

25

Material accountancy measurement techniques in dry-powdered processing of nuclear spent fuels.  

SciTech Connect

The paper addresses the development of inductively coupled plasma-mass spectrometry (ICPMS), thermal ionization-mass spectrometry (TIMS), alpha-spectrometry, and gamma spectrometry techniques for in-line analysis of highly irradiated (18 to 64 GWD/T) PWR spent fuels in a dry-powdered processing cycle. The dry-powdered technique for direct elemental and isotopic accountancy assay measurements was implemented without the need for separation of the plutonium, uranium and fission product elements in the bulk powdered process. The analyses allow the determination of fuel burn-up based on the isotopic composition of neodymium and/or cesium. An objective of the program is to develop the ICPMS method for direct fissile nuclear materials accountancy in the dry-powdered processing of spent fuel. The ICPMS measurement system may be applied to the KAERI DUPIC (direct use of spent PWR fuel in CANDU reactors) experiment, and in a near-real-time mode for international safeguards verification and non-proliferation policy concerns.

Wolf, S. F.

1999-03-24

26

Application of new synchrotron powder diffraction techniques to anomalous scattering from glasses  

NASA Astrophysics Data System (ADS)

The authors have applied two synchrotron powder diffraction techniques to the measurement of high quality anomalous scattering diffraction data for amorphous materials. One of these methods, which uses a curved perfect crystal analyzer to simultaneously diffract multiple powder lines into a position sensitive detector has been shown to possess high resolution, low background and very high counting rates. This data measurement technique provides excellent energy resolution while minimizing systematic errors resulting from detector non-linearity. Anomalous scattering data for a cesium germanate glass collected using this technique will be presented. The second powder diffraction technique uses a flat analyzer crystal to deflect multiple diffraction lines out of the equatorial plane. Calculations show that this method possesses sufficient energy resolution for anomalous scattering experiments when a perfect crystal analyzer is used and is experimentally much simpler. Future studies will make use of a rapid sample changer allowing the scattering from the sample and a standard material (a material not containing the anomalous scatterer) to be measured alternately at each angle, reducing systematic errors due to beam instability or sample misalignment.

Beno, M. A.; Knapp, G. S.; Armand, P.; Price, D. L.; Saboungi, M. L.

1994-08-01

27

Ultrasound-assisted powder-coating technique to improve content uniformity of low-dose solid dosage forms  

Microsoft Academic Search

An ultrasound-assisted powder-coating technique was used to produce a homogeneous powder formulation of a low-dose active\\u000a pharmaceutical ingredient (API). The powdered particles of microcrystalline cellulose (MCC; Avicel PH-200) were coated with a 4% m\\/V aqueous solution of riboflavin sodium phosphate, producing a uniform drug layer on the\\u000a particle surfaces. It was possible to regulate the amount of API in the

Natalja Genina; Heikki Rikknen; Osmo Antikainen; Jyrki Heinmki; Jouko Yliruusi

2010-01-01

28

a New Combustion Synthesis Technique for Rare Earth-Doped Iii-Nitride Luminescent Powders  

NASA Astrophysics Data System (ADS)

A new low temperature method to produce ((RE)xGa1-x)2O3(1?x?0 and RE=Eu, Yb, Pr and Tm) powders with high purity, high chemical homogeneity and improved crystallinity has been developed. This procedure produces finely divided powders through an exothermic reaction between the precursors. The process starts with aqueous solutions of RE(NO3)3 and Ga(NO3)3 as the precursors and hydrazine as the (non-carbonaceous) fuel. The combustion reaction occurs when heating the precursors between 150 and 200C in a closed vessel filled with an inert gas (Ar), which yields (RExGa1-x)2O3 directly. The preparation of RE-doped Ga2O3 powders was using a new combustion synthesis technique (Hydrazine / metal nitrate method). The preparation of Eu-doped GaN was using the ammonium hexafluoro-metal method. The powders were crystalline and high-purity as determined by XPS, EDS, SEM and XRD measurements.

Ramos, F. E.; Garcia, R.; Hirata, G. A.; Bosze, E. J.; McKittrick, J.

29

Lifting techniques for finger marks on human skin previous enhancement by Swedish Black powder A preliminary study  

Microsoft Academic Search

An examination was done to investigate whether certain lifting techniques can lift recovered latent fingerprints on human skin surfaces of living subjects. For recovery Swedish Soot powder mixture (Swedish Black) was used.Donors intentionally placed fingerprints on the skin surface of living subjects. Finger marks were then in all cases recovered with Swedish Black powder. The procedure was repeated after 1h

Matej Trapecar

2009-01-01

30

A sol-powder coating technique for fabrication of yttria stabilised zirconia  

SciTech Connect

Yttria stabilised zirconia has been prepared using a simple sol-powder coating technique. The polymeric yttria sol, which was prepared using 1,3 propanediol as a network modifier, was homogeneously mixed with nanocrystalline zirconia powder and it showed a dual function: as a binder which promoted densification and a phase modifier which stabilised zirconia in the tetragonal and cubic phases. Thermal analysis and X-ray diffraction revealed that the polymeric yttria sol which decomposed at low temperature into yttrium oxide could change the m {sup {yields}} t phase transformation behaviour of the zirconia, possibly due to the small particle size and very high surface area of both yttria and zirconia particles allowing rapid alloying. The sintered samples exhibited three crystalline phases: monoclinic, tetragonal and cubic, in which cubic and tetragonal are the major phases. The weight fractions of the individual phases present in the selected specimens were determined using quantitative Rietveld analysis.

Wattanasiriwech, Darunee [School of Science, Mae Fah Luang University, Chiangrai 57100 (Thailand)]. E-mail: darunee@mfu.ac.th; Wattanasiriwech, Suthee [School of Science, Mae Fah Luang University, Chiangrai 57100 (Thailand); Stevens, Ron [Department of Engineering and Applied Science, University of Bath (United Kingdom)

2006-08-10

31

Replaceable nozzles for insertion into a drilling bit formed by powder metallurgical techniques and a method for manufacturing the same  

SciTech Connect

This patent describes an improvement in a method of disposing threaded hydraulic nozzles in a drill bit manufactured by powder metallurgical techniques. The bit is composed of a brittle material, the improvement consisting of the step of molding a threaded bore into the drill bit using the powder metallurgical techniques. Molding of the threaded bore includes molding threads separated by a flat spacing between each thread.

Voight, R.W.; Robin, J.R.; Lovato, L.G.; Balkenbush, R.J.; McDermaid, J.D.

1986-02-04

32

Ultrasound-assisted powder-coating technique to improve content uniformity of low-dose solid dosage forms.  

PubMed

An ultrasound-assisted powder-coating technique was used to produce a homogeneous powder formulation of a low-dose active pharmaceutical ingredient (API). The powdered particles of microcrystalline cellulose (MCC; Avicel PH-200) were coated with a 4% m/V aqueous solution of riboflavin sodium phosphate, producing a uniform drug layer on the particle surfaces. It was possible to regulate the amount of API in the treated powder. The thickness of the API layer on the surface of the MCC particles increased near linearly as the number of coating cycles increased, allowing a precise control of the drug content. The tablets (n = 950) prepared from the coated powder showed significantly improved weight and content uniformity in comparison with the reference tablets compressed from a physical binary powder mixture. This was due to the coated formulation remaining uniform during the entire tabletting process, whereas the physical mixture of the powders was subject to segregation. In conclusion, the ultrasound-assisted technique presented here is an effective tool for homogeneous drug coating of powders of irregular particle shape and broad particle size distribution, improving content uniformity of low-dose API in tablets, and consequently, ensuring the safe delivery of a potent active substance to patients. PMID:20730575

Genina, Natalja; Rikknen, Heikki; Antikainen, Osmo; Heinmki, Jyrki; Yliruusi, Jouko

2010-08-21

33

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

PubMed

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 a sacrificial wax template, fabricated using a commercial 3D-printer. Powder metallurgy processes were employed to generate the titanium scaffolds by filling around the wax template with titanium slurry. In the attempt to optimise the powder metallurgy technique, variations in slurry concentration, compaction pressure and sintering temperature were investigated. By altering the wax design template, pore sizes ranging from 200 to 400 microm were achieved. Scaffolds with porosities of 66.8 +/- 3.6% revealed compression strengths of 104.4+/-22.5 MPa in the axial direction and 23.5 +/- 9.6 MPa in the transverse direction demonstrating their anisotropic nature. Scaffold topography was characterised using scanning electron microscopy and microcomputed tomography. Three-dimensional reconstruction enabled the main architectural parameters such as pore size, interconnecting porosity, level of anisotropy and level of structural disorder to be determined. The titanium scaffolds were compared to their intended designs, as governed by their sacrificial wax templates. Although discrepancies in architectural parameters existed between the intended and the actual scaffolds, overall the results indicate that the porous titanium scaffolds have the properties to be potentially employed in orthopaedic applications. PMID:18556060

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

2008-06-16

34

Single-crystal growth of 4-hydroxy-3-methoxy benzaldehyde by the Bridgman technique and its characterization  

NASA Astrophysics Data System (ADS)

Single-crystal growth of 4-hydroxy-3-methoxy benzaldehyde (vanillin), an excellent molecular nonlinear optical (NLO) material, from the melt using the Bridgman technique is reported for the first time. Differential thermal analysis experiments indicated that the substance melts congruently at 81 C. A precise temperature profile plot of the resistive furnace used was measured using a simple PC-based time-temperature data logging system. Powder X-ray diffraction analysis of the grown crystal revealed the crystal belongs to the monoclinic system. Fourier transform infrared spectra were used to assign various modes and identify the functional groups. The crystal exhibited a wide window of transmission unlike other organic NLO crystals. The optical second harmonic generation conversion efficiency of vanillin was determined using the Kurtz powder technique.

Kannan, V.; Jayaprakasan, M.; Bairava Ganesh, R.; Ramasamy, P.

2006-08-01

35

Production of high-speed steel by the powder metallurgy technique  

Microsoft Academic Search

with regeneration of the alcohol by distillation. With swarf, comminution in attrition or vibratory mills was found to be much more rapid, and resulted in the formation of finer powders. The mean size of carbide inclusions in the particles of powders comminuted under the optimum conditions was 0.8-1.5 p. During comminution, the specific surface of the powders grew, and consequently

S. S. Kiparisov; G. A. Meerson; V. S. Panov; V. I. Tret'yakov; M. M. Smirnova; Ya. K. Manikatov

1975-01-01

36

Bray\\/Kurtz, Mehlich III, AB\\/D and ammonium acetate extractions of P, K and MG in four oklahoma soils  

Microsoft Academic Search

Multi?element soil extraction solutions offer increased convenience in soil testing laboratory operations. The recently developed Mehlich III and ammonium bicarbonate?DTPA multi?element extraction solutions were each compared with the more conventional Bray\\/Kurtz extractant for P determination and with 1N ammonium acetate for K and Mg determinations. The latter two solutions are single and tri?element extractants in current use by the Oklahoma

E. A. Hanlon; G. V. Johnson

1984-01-01

37

Bray and Kurtz phosphorus (p1), 1m potassium chloride, and saturated calcium oxide extraction of soil nitrate comparison to 2m potassium chloride  

Microsoft Academic Search

Labor and laboratory expense could be reduce if soil extractable nitrate (NO3) was extracted simultaneously with other routinely used soil extractants. This study was conducted to compare 1M potassium chloride (KCl), saturated calcium oxide (CaO), and Bray and Kurtz P1?extractable soil NO3, the proposed new method to 2M KCl. Nitrate was extracted from 140 selected soils with 1M KCl, saturated

Byron Vaughan; J. Denning; H. Frank

1995-01-01

38

The effect of the granulometric composition of a hydroxyapatite powder on the structure and phase composition of coatings deposited by the detonation gas spraying technique  

NASA Astrophysics Data System (ADS)

The granulometric composition of a hydroxyapatite powder has been investigated. The initial powder has been classified into particle size ranges (0.1-10, 10-20, 20-30, and 50-300 ?m). Coatings prepared from a hydroxyapatite powder of different size have been deposited by the detonation gas spraying technique. The structure and phase composition of the coatings have been studied. Changing the initial granulometric composition of the powder mixture is shown to provide control over the sprayed surface roughness.

Popova, A. A.; Yakovlev, V. I.; Legostaeva, E. V.; Sitnikov, A. A.; Sharkeev, Yu. P.

2013-04-01

39

Study of rapidly solidified atomization technique and production of metal alloy powders  

Microsoft Academic Search

In this paper, a new rapidly quenched atomization equipment, high pressure gas centrifugal rotation disc (HPGCRD) is reported. Various kinds of amorphous, quasi-crystalline and micro-crystalline powders were prepared by the HPGCRD device. The average diameter of the powders prepared by the HPGCRD was in the range of 515?m. SEM observation showed that the shapes of the powders appeared sphere or

Zheng Fuqian; Xie Ming; Liu Jianliang; Lu Xianyong; Guan Weiming; Shi An; Deng Zhongmin

2001-01-01

40

Experimental and Theoretical Aspects of Ab Initio Structure Determination Using Powder Diffraction Techniques,  

National Technical Information Service (NTIS)

Powder diffraction has developed into an important crystallographic tool over the past thirty years largely because of the success of the Rietveld profile method in structure refinement. The improvements in instrumentation in this period have led to the s...

W. I. F. David M. W. Johnson C. C. Wilson

1987-01-01

41

Microstructure and Mechanical Properties of Titanium Components Fabricated by a New Powder Injection Molding Technique  

SciTech Connect

We have developed a powder injection molding (PIM) binder system for titanium that employs naphthalene as the primary constituent to facilitate easy binder removal and mitigate problems with carbon contamination. In the study presented here, we examined densification behavior, microstructure, and mechanical properties in specimens formed by this process. In general, we found that we could achieve tensile strengths comparable to wrought titanium in the PIM-formed specimens, but that maximum elongation was less than expected. Chemical and microstructural analyses suggest that use of higher purity powder and further process optimization will lead to significant improvements in ductility.

Nyberg, Eric A.; Miller, Megan R.; Simmons, Kevin L.; Weil, K. Scott

2005-05-01

42

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

43

The study on various wet chemistry techniques on YBa 2Cu 3O 7? ? superconducting oxides powder preparation  

Microsoft Academic Search

This paper reports on the results of four different wet chemical techniques used for the synthesis of superconducting oxides, YBa2Cu3O7 (YBCO). YBCO samples were prepared by complexion citric gel route (CT), acetatetartrate solgel (ASG), oxalate\\/ethanol coprecipitation (COP), and acetatetartrate solgel solid-state reaction (ASG-SSR) techniques. Each of the YBCO powders was annealed for 4h at 880C, 900C, 920C, and 950C to

L. M. Yeoh; R. Abdshukor

2008-01-01

44

Effect of precursor concentrations on structural, microstructural and optical properties of nanocrystalline ZnO powder synthesized by an ultrasonic atomization technique  

Microsoft Academic Search

In this paper, we report on the effect of concentration on nanocrystalline ZnO powder prepared by an ultrasonic atomization technique, which is a promising method because of its simplicity, inexpensiveness and safety. The morphology and size of ZnO nanocrystallites associated with nanopowder were characterized by transmission electron microscopy (TEM). It revealed that the powder consisted of nanocrystallites with grain sizes

L A Patil; A R Bari; M D Shinde; Vinita Deo; M P Kaushik

2010-01-01

45

Role of powder properties and shaping techniques on the formation of pore-free YAG materials  

Microsoft Academic Search

A key feature of transparent ceramics is the absence of residual porosity because boundary between pores and ceramic grains is the origin for light scattering. Powders characterized by a grain size in the nanometric range are generally adopted for obtaining transparent ceramics because of their superior reactivity, but the formation of undesired secondary phase related to the presence of impurities,

Laura Esposito; Andreana Piancastelli

2009-01-01

46

Knowledge based and adaptive computational techniques for concurrent design of powder metallurgy parts  

Microsoft Academic Search

The practice of concurrent engineering (CE) is adopted widely to facilitate integrated design and manufacture by industry in order to maintain competitiveness in the market place. Use of near net-shape processes like powder metallurgy (PM) within a CE environment can give added benefits in terms of material utilisation and environmental considerations. A system for concurrent design of PM parts is

R. P Cherian; P. S Midha; L. N Smith; A. G Pipe

2001-01-01

47

Ionic liquids for simultaneous preconcentration of some lanthanoids using dispersive liquid-liquid microextraction technique in uranium dioxide powder.  

PubMed

Ionic liquids in a dispersive liquid-liquid microextraction technique were used for determination of lanthanoids such as samarium, europium, gadolinium, and dysprosium in uranium dioxide powder. In this process, an appropriate mixture of extraction solvent and disperser is rapidly injected into an aqueous sample containing samarium, europium, gadolinium, and dysprosium ions complexes with 1-hydroxy-2, 5-pyrrolidinedione, and consequently a cloudy solution is formed. It consists of fine droplets of extraction solventwhich are dispersed entirely into the aqueous phase. After centrifugation of this solution, the whole enriched phase was determined by inductively coupled plasma optical emission spectrometry. In the present work, the preconcentration factor, limit of detection, and relative standard deviation were investigated for samarium, europium, gadolinium, and dysprosium in uranium dioxide powder. PMID:19368197

Mallah, Mohammad H; Shemirani, Farzaneh; Maragheh, Mohammad G

2009-03-15

48

Determination of specific surface area of uranium oxide powders using differential thermal analysis technique  

Microsoft Academic Search

The two step oxidation of UO2+x and reduction of U3O8 powders observed during Differential Thermal Analysis (DTA) has been exploited to determine their Specific Surface Areas\\u000a (SSAs). The results obtained by this method have been compared with the Braunauer, Emmett and Teller (BET) method and are\\u000a found to be in good agreement in the SSA range of 24 m2\\/gm in

Y. Balaji Rao; R. B. Yadav; R. Narazana Swamy; B. Gopalan; S. Syamsundar

1995-01-01

49

A powder technique for measuring the noncritical phase-matching frequency  

NASA Astrophysics Data System (ADS)

Quantitative criteria are proposed for determining the noncritical phase-matching frequency according to the second-harmonic radiation spectrum in the case of the nonlinear conversion of the frequency of a tunable laser in nonlinear-crystal powders. The noncritical phase-matching frequencies in p-nitro-p'methyl benzalaniline and 2,4-dinitrophenol crystals were determined. The frequency dispersion of the refractive indices of the latter crystals was also measured.

Iakovlev, Iu. O.; Lavrovskii, E. A.

1990-11-01

50

Sinterability of Yttria-Stabilized Zirconia Powder Prepared by Ultrasonic Spray Freeze-Drying Technique  

Microsoft Academic Search

Tetragonal zirconia poly crystals (Y-TZP)containing 30 mole% yttria were prepared by (i) the ultrasonic spraying of solutions containing desired amounts of components into a chamber chilled by liquid nitrogen, (ii)the subliming of the ice from the frozen materials and (iii) the calcining of the remaining materials. The resulting Y-TZP powder was composed of ultrafine primary particles with sizes below 0.05

Shinji Iwaida; Kiyoshi Itatani; F. Scott Howell; Akira Kishioka; Makio Kinoshita

1994-01-01

51

Technique of Formation of an Axisymmetric Heterogeneous Flow During Thermal Spraying of Powder Materials  

NASA Astrophysics Data System (ADS)

The paper presents an investigation of a unit of annular injection of powder materials into a thermal plasma flow. The unit is designed for the electric-arc direct-current plasma torch with a sectioned inter-electrode insert up to 100 kW, which was developed earlier. Energy characteristics (thermal efficiency and thermal power of the plasma jet) and spectra of plasma torch current and voltage fluctuations are described. The characteristics of the radial temperature distribution in the plasma jet in the annular and point powder injection cases are compared. A multi-channel spectrometer with a photo-diode array was implemented for the measurements. It is shown that, in contrast to point injection of powder particles, which is carried out across the jet on the nozzle exit, distributed annular injection with gas-dynamic focusing provides a dense axisymmetric heterogeneous flow, in which almost all particles pass through a high-temperature and high-speed area near the plasma jet axis.

Kuz'min, V. I.; Mikhal'Chenko, A. A.; Kovalev, O. B.; Kartaev, E. V.; Rudenskaya, N. A.

2012-01-01

52

Precise measurement of the lattice spacing of LaB{sub 6} standard powder by the x-ray extended range technique using synchrotron radiation  

SciTech Connect

We used the basis of the x-ray extended range technique to measure the lattice spacing of LaB{sub 6} standard powder samples relative to silicon 640b standard powder samples with an accuracy of 5x10{sup -5} A. Measurements were not constrained to one energy but were carried out over a 5 keV-20 keV energy range. These measurements used powder diffraction to determine the synchrotron beam energy, to diagnose discrepancies in the nominal calibrated beam energies, and to determine beam energy bandwidths as a function of energy. More specifically, this technique is able to yield a result independent of certain energy-dependent systematics and to yield the most accurate determination of the lattice spacing of NIST SRM 660 LaB{sub 6} standard powder so far undertaken. This has direct application to beam line energy calibration, structural evaluation, edge energy calibration, and lattice spacing determinations.

Chantler, C.T.; Tran, C.Q. [School of Physics, University of Melbourne, Victoria 3010 (Australia); Cookson, D.J. [ANSTO, Private Mail Bag 1, Menai, New South Wales 2234 (Australia); Chem-Mat-CARS-CAT (Sector 15, Building 434D), Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 6043 (United States)

2004-04-01

53

[Effect of powder's particle size on the quantitative prediction of volatile oil content in Zanthoxylum bungeagum by NIR technique].  

PubMed

The traditional chemical methods to measure the volatile oil content of zanthoxylum bungeagum encounter some problems such as long time and low efficiency, so it is difficult to achieve rapid detection. One hundred forty-one samples including 74 zanthoxylum bungeagum maxim and 67 zanthoxylum schinifolium Sieb. et zucc were collected, from many provinces in China such as Shan Xi, Si Chuan, Gan Su, Chong Qing, Yun Nan, etc. Each sample was crushed and sorted to 8 kinds of powder samples according to the particle size of 120-mesh, 100-mesh, 80-mesh, 60-mesh, 40-mesh, 20-mesh, 10-mesh, respectively, including the material retained by the 10-mesh sieve. Then, each powder sample was labeled by one of the following serial numbers: 120, 100, 080, 060, 040, 020, 010 and 000. For each sample, the NIR spectra of 8 different kinds of particle size powders were measured using a Bruker MATRIX-I FT-NIR spectrometer. Then, the 8 different kinds of particle size powders of each sample were mixed uniformly. The volatile oil content was measured in each sample according to the distillation stipulated by the Forestry Standard of PRC-Quality Classify of Prickly Ash (LY/T 1652-2005). Based on near infrared spectroscopy technique and partial least squares (PLS), 8 calibration models of predicting volatile oil content were established by 141 powder samples with 8 different kinds of particle size. Experiments indicatd that the model was the best with the powder's particle size of 40-mesh and the determination coefficient (r2(141)) and the root mean square error of cross validation (RMSECV141) were 0.9364 and 0.421, respectively. The model was established by the calibration set with 105 samples with particle size of 40-mesh. Applying the model to the test set with 36 samples, the determination coefficient (r2(36)), the root mean square error of prediction (RMSEP36), the relative standard deviation (RSD36), and the ratio of prediction to deviation (RPD36) were 0.9233, 0.452, 11.66%, and 3.624, respectively. The model, based on the same sample set but optimized by OPUS 5.0, was developed by spectral data pretreatment of the Mean Centering+Vector Normalization in the spectral region of 6 100.1-5 774.2 cm(-1) and 4 601.6-4 424.2 cm(-1). Using the model to predict the test set, r2(36), RMSEP36, RSD36, and RPD36 were 0.9862, 0.192, 4.95%, and 8.517, respectively. The results showed that the model built by samples passed through 40-mesh screen was the best and rapid detection of volatile oil content in zanthoxylum bungeagum by NIR was feasible and efficient. PMID:18619296

Zhu, Shi-Ping; Wang, Gang; Yang, Fei; Kan, Jian-Quan; Guo, Jing; Qiu, Qing-Miao

2008-04-01

54

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

55

Solid-state structural properties of 2,4,6-trimethoxybenzene derivatives, determined directly from powder X-ray diffraction data in conjunction with other techniques  

SciTech Connect

Structural properties of 2,4,6-trimethoxybenzaldehyde, 2,4,6-trimethoxybenzyl alcohol and 2,4,6-trimethoxyacetophenone have been determined directly from powder X-ray diffraction data, using the direct-space Genetic Algorithm (GA) technique for structure solution followed by Rietveld refinement. Structural similarities and contrasts within this family of materials are elucidated. The work illustrates the value of utilizing information from other sources, including spectroscopic data and computational techniques, as a means of augmenting the structural knowledge established from the powder X-ray diffraction data.

Pan Zhigang [School of Chemistry, Cardiff University, Park Place, Cardiff CF10 3AT, Wales (United Kingdom); Xu Mingcan [School of Chemistry, Cardiff University, Park Place, Cardiff CF10 3AT, Wales (United Kingdom); Cheung, Eugene Y. [School of Chemistry, Cardiff University, Park Place, Cardiff CF10 3AT, Wales (United Kingdom); Platts, James A. [School of Chemistry, Cardiff University, Park Place, Cardiff CF10 3AT, Wales (United Kingdom); Harris, Kenneth D.M. [School of Chemistry, Cardiff University, Park Place, Cardiff CF10 3AT, Wales (United Kingdom)]. E-mail: HarrisKDM@cardiff.ac.uk; Constable, Edwin C. [Department of Chemistry, University of Basel, Spitalstrasse 51, 4056 Basel (Switzerland); Housecroft, Catherine E. [Department of Chemistry, University of Basel, Spitalstrasse 51, 4056 Basel (Switzerland)

2006-10-15

56

Development and in vitro evaluation of ketoprofen extended release pellets using powder layering technique in a rotary centrifugal granulator.  

PubMed

Powder layering technique was evaluated using laboratory scale centrifugal granulator instrument to prepare extended release pellet dosage form of ketoprofen. Ethyl cellulose and shellac polymers were used for drug layering and extended release coating in the same apparatus. Inert sugar spheres were intermittently treated with drug powder and binding solution. Combination of ethyl cellulose (45cps) and shellac was evaluated as binders at different levels (1:3 ratio, at 6%, 12%, 16% and 21%w/w polymer) for drug loading and for extended release coating (1:3 ratio at 2%, 4% and 7% w/w polymer). Pellets were evaluated for drug release study using paddle apparatus in pH 6.8 Phosphate buffer, 900ml at 100 rpm. Ethyl cellulose and shellac when used as binder during drug layering did not extend the ketoprofen release beyond 4h. However, coating of drug loaded pellets using ethyl cellulose and shellac resulted in extended release profile of ketoprofen for about 10h. Ethyl cellulose coating alone at a level of 3% w/w resulted in extended release profile. Coated pellets were evaluated for sphericity, Hardness-Friability Index and scanning electron microscopy. Scanning electron micrographs of the pellets showed a uniform coating of polymer on the core pellets substantiating the use of centrifugal granulator for extended release coating. Release pattern from the optimized batch was best explained by Higuchi's model. The drug release pattern from the pellets was found to be Non-Fickian anomalous type, involving both diffusion and erosion mechanism. Accelerated stability study of the coated pellets filled in hard gelatin capsule was conducted for 3-month period and observed for the effect on drug release profile. PMID:21118082

Pai, Raveendra; Pai, Aruna; Srivastava, Birendra; Kohli, Kanchan

2011-02-01

57

Comparison of NDA and DA measurement techniques for excess Pu powders at the Hanford Site: Operator and IAEA experience  

SciTech Connect

Quantitative physical measurements are necessary components of the International Atomic Energy Agency (IAEA) nuclear material safeguards verification regime. In December 1994, IAEA safeguards were initiated on an inventory of plutonium-bearing oxide and scrap items in Vault 3 of the 2736-Z Building of the Plutonium Finishing Plant on the United States Department of Energy`s (USDOE) Hanford Site. The material originated in the United States nuclear weapons complex. The diversity of the chemical form and the heterogenous physical form of the plutonium in this inventory were expected to challenge the target precision and accuracy of methods employed by IAEA: quantitative destructive analytical techniques (which are susceptible to sampling error) and quantitative coincident neutron measurements (which rely on knowledge of the material`s chemical form and purity). Because of the diverse and heterogenous nature of plutonium-bearing scrap, plant operations increasingly have adopted calorimetric techniques both for item inventory measurements and for verification purposes. During the recent advent of IAEA safeguards at Vault 3, a set of destructive and nondestructive methods were applied to a number of inventory items (cans of plutonium-bearing powders) with widely ranging chemical purities. Results of these measurements, gathered by the operator`s and IAEA`s laboratories and instruments as well as by instruments from Pacific Northwest Laboratory and USDOE`s Los Alamos National Laboratory (LANL), are presented and statistically compared.

Welsh, T.L.; McRae, L.P.; Delegard, C.H. [and others

1995-06-01

58

Plasma Data Processing, Velocity Measurements, and Nano-Sized Titanium Powder Production by Plasma Quench Techniques.  

NASA Astrophysics Data System (ADS)

Fourier transform techniques are used to perform the Abel inversion. Noisy and asymmetric data are filtered in the frequency domain and symmetrized by phase correction methods which have been developed in Fourier spectroscopy. A procedure which allows the degree of asymmetry to be distinguished from random noise is described. The procedure is illustrated with a Gaussian distribution which is noisy and asymmetric and with optical emission data taken in a plasma jet in a side-on configuration. The Fourier transform procedure is computationally efficient and it can filter the noise, determine the degree of cylindrical asymmetry, and perform the Abel inversion simultaneously. The optical emission intensity in a low-swirl transient argon plasma jet at atmospheric pressure has been analyzed to determine plasma gas velocities along the center axis in a region from 0 to 10 mm from the jet exit. An abrupt decrease at about 4 mm from the jet exit is observed under all gas-flow and current conditions. Measurements on a second low-swirl jet with somewhat different anode -cathode geometry did not show such a transition in this spatial region and indicate that the results are very dependent on torch geometry. Nano-sized titanium particles were synthesized by feeding titanium tetrachloride (TiCl_4 ) into an argon-hydrogen plasma system which consisted of a D.C. plasma torch and a convergent-divergent supersonic reactor. The theory of convergent-divergent nozzles is briefly described and is used to predict the temperature inside the reactor from the measurements of the temperature distribution in the exhausting low pressure chamber. The free energy minimization technique is used to determine the mole fraction of the components in the plasma system. The hot plasma mixture undergoes an approximate adiabatic isentropic expansion in the reactor and the energy in the mixture, or its enthalpy, is converted to unidirectional velocity and hence the gas temperature is quenched very quickly. Results show that the system can achieve a temperature quench rate of greater than 10^8 K/sec and produce particles of ~5 nm diameter with an approximately uniform size distribution.

Dong, Junyi

59

Effect of precursor concentrations on structural, microstructural and optical properties of nanocrystalline ZnO powder synthesized by an ultrasonic atomization technique  

NASA Astrophysics Data System (ADS)

In this paper, we report on the effect of concentration on nanocrystalline ZnO powder prepared by an ultrasonic atomization technique, which is a promising method because of its simplicity, inexpensiveness and safety. The morphology and size of ZnO nanocrystallites associated with nanopowder were characterized by transmission electron microscopy (TEM). It revealed that the powder consisted of nanocrystallites with grain sizes between 8 and 15 nm. These values match the grain sizes (8-14 nm) calculated from x-ray diffraction (XRD). The XRD and TEM studies of ZnO nanopowder showed that crystallite sizes were observed to increase with an increase in the concentration of solution. The d values calculated from electron diffraction patterns (TEM) of ZnO nanopowder were also in agreement with the d values calculated from XRD. The synthesized nanopowders exhibited a direct band gap (Eg) in the range of 3.36-3.42 eV.

Patil, L. A.; Bari, A. R.; Shinde, M. D.; Deo, Vinita; Kaushik, M. P.

2010-09-01

60

Metal Powders (Metall Pulver).  

National Technical Information Service (NTIS)

This book discusses metal powders for powder metallurgy, specific topics include Electrolytic copper powder, Copper alloy powders, Lead powders, tin powders, Partially prealloyed powders, Premixes, Mixed powders to customers' specifications, Quality contr...

1986-01-01

61

Physicochemical differences after densifying radio frequency plasma sprayed hydroxyapatite powders using spark plasma and conventional sintering techniques  

Microsoft Academic Search

The aim of this comparative study was to elucidate the characterization of spherical radio frequency (RF) plasma sprayed hydroxyapatite (HA) powder consolidated by spark plasma sintering (SPS) and conventional sintering methods. SPS processing took place under low vacuum of 4.5Pa at the temperature of 9001200C for 3min with a heating rate of 100C\\/min. The conventional processing was conducted at the

J. L. Xu; K. A. Khor; R. Kumar

2007-01-01

62

New Applications of Electron Diffraction in the Pharmaceutical Industry: Polymorph Determination by Using a Combination of Electron Diffraction and Synchrotron X-ray Powder Diffraction Techniques  

NASA Astrophysics Data System (ADS)

Electron diffraction has been recently used in the pharmaceutical industry to study the polymorphism in crystalline drug substances. While conventional X-ray diffraction patterns could not be used to determine the cell parameters of two forms of the microcrystalline GP IIb/IIIa receptor antagonist roxifiban, a combination of electron single-crystal and synchrotron powder diffraction techniques were able to clearly distinguish the two polymorphs. The unit-cell parameters of the two polymorphs were ultimately determined using new software routines designed to take advantage of each technique's unique capabilities. The combined use of transmission electron microscopy (TEM) and synchrotron patterns appears to be a good general approach for characterizing complex (low-symmetry, large-unit-cell, micron-sized) polymorphic pharmaceutical compounds.

Li, Z. G.; Harlow, R. L.; Foris, C. M.; Li, H.; Ma, P.; Vickery, R. D.; Maurin, M. B.; Toby, B. H.

2002-04-01

63

A Robust Technique for Two-Dimensional Separation of Undistorted Chemical-Shift Anisotropy Powder Patterns in Magic-Angle-Spinning NMR  

NASA Astrophysics Data System (ADS)

A robust magic-angle-spinning experiment for separating undistorted, quasi-static chemical-shift powder patterns is presented. It is derived from the technique of R. Tycko, G. Dabbagh, and P. Mirau (1989, J. Magn. Reson. 85, 265), but uses 360 instead of 180 pulses. In combination with a suitable phase sequence, this makes the spectral patterns very insensitive to pulse-length errors and other imperfections, as demonstrated both experimentally and theoretically. This method, termed separation of undistorted powder patterns by effortless recoupling (SUPER), can be used at standard spinning speeds, between 2.5 and 5 kHz, and with standard radiofrequency power levels (in particular, for protons, a decoupling field strength ?B1/2? of less than 80 kHz). No significant artifacts are observed even for samples extending to the ends of the radiofrequency coil. The method has been applied to samples containing various sp2- and sp3-hybridized carbon sites. Even for the methylene groups in polyethylene, a system with very strong C-H and H-H dipolar couplings and only moderate chemical-shift anisotropy (CSA), a useful CSA powder pattern has been obtained. With a CSA scaling factor of 0.155, accuracies of +/-5, +/-3, and +/-1 ppm of the principal values can be achieved for protonated aromatic carbons, unprotonated sp2-hybridized groups, and aliphatic sites, respectively. Examples of CSA-based assignment of COOC vs other COO or CON groups, and of aromatic vs olefinic C dbond C carbons are shown, for both small molecules and polymers. .

Liu, S.-F.; Mao, J.-D.; Schmidt-Rohr, K.

2002-03-01

64

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

65

Explosive containment with spherically tamped powders  

Microsoft Academic Search

An effective technique for maximizing the explosive charge that a given container can safely handle is to fill the space between the charge and the container walls with a porous medium or a powder. Using the wrong powder, however, can be worse than using no powder at all. Moreover, a powder-filled container that performs very well with a small charge

L. A. Glenn

1986-01-01

66

Surface characterization of emulsified lithium powder electrode  

Microsoft Academic Search

The surface modification of Li powder was attempted in order to enhance the electrochemical properties of the electrodes used in rechargeable batteries. To create a native LiF film on Li powder, Li powder was manufactured using a droplet emulsion technique (DET) process by introducing fluoride as a surfactant. The surface modification of the Li powder was confirmed by means of

Seung-Taek Hong; Jin-Suk Kim; Suk-Jun Lim; Woo Young Yoon

2004-01-01

67

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.

Society, American C.

2000-01-01

68

A technique to measure heats of reaction of titanium-boron, aluminim-titanium-boron, and aluminum-titanium-boron-carbon powder blends  

NASA Astrophysics Data System (ADS)

In this research, a modification to initiation aid ignition in bomb calorimetry that involves systemically blending levels of boron and potassium nitrate initiation aids with a bulk structural energetic elemental power blend is developed. A regression is used to estimate the nominal heat of reaction for the primary reaction. The technique is first applied to the synthesis of TiB 2 as a validation study to see if close proximity to literature values can be achieved. The technique is then applied to two systems of interest, Al-Ti-B, and Al-Ti-B4C. In all three investigations, x-ray diffraction is used to characterize the product phases of the reactions to determine the extent and identity of the product phases and any by-products that may have formed as a result of adding the initiation aid. The experimental data indicates the technique approximates the heat of reaction value for the synthesis of TiB2 from Ti-B powder blends and the formation of TiB2 is supported by volume fraction analysis by x-ray diffraction. Application to the Al-Ti-B and Al-Ti-B4C blends show some correlation with variation of the initiation aid, with x-ray diffraction showing the formation of equilibrium products. However, these blends require further investigation to resolve more complex interactions and rule out extraneous variables.

Baker, Andrew H.

69

Structural investigations of zeolites ERS-7, mordenite, and sodalite using a combination of powder diffraction and computer simulation techniques  

NASA Astrophysics Data System (ADS)

The framework structure of dehydrated template-free ERS-7 was determined by a combination of synchrotron X-ray powder diffraction and the simulated annealing approach of Deem and Newsam. The orthorhombic unit cell ( a = 9.79976(4) A, b = 12.41163(6) A, c = 22.86063(11) A) contains 6 tetrahedral framework atoms (Si/Al = 8.4), all on general positions, and 14 bridging oxygens. It can be constructed as a network of purely face-sharing 17-sided (465 46582) "picnic-basket"-shaped cages that are stacked so as to form a 1D 8-ring channel system (3.5 A x 4.7 A) that runs through the handles of the baskets. Three Bronsted acid sites were then identified via a multi-dataset Rietveld refinement against both PXD and PND data. Previous reports of correlations between diffracted intensities and aluminum content in as-synthesized Na mordenites (Si/Al = 5 to 10) are shown to be explained as a selective suppression of the (h, k,? = 2n + 1) reflections caused by linear faulting along the main channel axis. Computer generated structures with up to 500,000 atoms were used to simulate the diffuse scattering patterns for several different correlated defect models, which were then compared to previously reported experimental results. The regions of faulted material are shown to consist of c-axis chains of shifted framework 4-rings, such that neighboring pairs of chains along the a-axis shift together. The intensity of odd-? reflections is suppressed by a factor of (1 - 2po) 2 where po is the fraction of fault-shifted material, the intensity of the diffusely scattered sheets in the odd-? planes perpendicular to c* increases in proportion to po(1 - po), and the in-plane modulations of these sheets are shown to have the form sin 2(pih/2). Variable-temperature synchrotron PXD data from dehydrated sodium sodalite, Na6[Al6Si6O24], reveals a structural phase transition at 500 K that involves both a commensurate ordering of the extra-framework Na cations and a one-dimensional incommensurate modulation of the framework. Peak splittings and superlattice reflections implicate an orthorhombically distorted supercell which is related to the original 9.1 A cubic cell by a 45 rotation about a 4-fold axis and a doubling of the volume (?2 a x ?2a x a). The incommensurate modulation vector is then shown to be [211]/8.9 on the commensurate supercell basis. The 88 unique orderings of the 12 Na cations of the supercell among its 16 available sites were enumerated, and each configuration was subjected to lattice energy minimization using an empirical interatomic potential. A unique solution was identified that minimizes the structural energy and also matches the experimental diffraction data. The high-temperature phase (Pm3n) is well described by dynamical disorder among the cation sites and also between opposite framework "partial collapse" angles.

Campbell, Branton J.

70

Low Porosity Powder Metallurgy Produced Components.  

National Technical Information Service (NTIS)

Components produced by powder metallurgy techniques are described herein. Embodiments of these components have little or no porosity therein after processing. Embodiments of these components are created by creating a preform from a powder; creating a comp...

G. Das

2004-01-01

71

Powdered Metal Sintering of Jet Vanes.  

National Technical Information Service (NTIS)

This report presents the successful efforts to use powdered metallurgy techniques in manufacturing jet vanes from sintered and copper infiltrated tungsten. Isostatic pressing of the powdered tungsten to net shape imparts sufficient hardening to allow hand...

M. J. Ripley-Lotee S. M. O'Neil

1982-01-01

72

Properties of Prealloyed Steel Powder Metallurgy Products.  

National Technical Information Service (NTIS)

A program to evaluate the properties of prealloyed steel powders, consolidated by various fabrication techniques, was conducted. Sixteen lots of low-alloy prealloyed steel powder, representing seven different major alloys (4130, 1040, 8620, 4640, 4650, 86...

R. E. Westerman K. R. Sump

1972-01-01

73

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.

Kessler, James H.; Galvan, Patricia M.

2007-01-01

74

Innovations in titanium powder processing  

NASA Astrophysics Data System (ADS)

One way of reducing the cost of titanium components is to use near-net shape powder-metallurgy techniques. This article describes a number of new approaches to producing components using the powder-metallurgy method for the aerospace, industrial, and consumer marketplaces.

Moxson, Vladimir; Senkov, O. N.; Froes, F. H.

2000-05-01

75

Laser powder deposition  

Microsoft Academic Search

Purpose The purpose of this paper is to review the state of the art of laser powder deposition (LPD), a solid freeform fabrication technique capable of fabricating fully dense functional items from a wide range of common engineering materials, such as aluminum alloys, steels, titanium alloys, nickel superalloys and refractory materials. Design\\/methodology\\/approach The main R&D efforts and the

Lino Costa; Rui Vilar

2009-01-01

76

Comprehensive Review of Black Powder.  

National Technical Information Service (NTIS)

A diligent attempt has been made to scrutinize black powder and the charcoal it contains as fully as possible, utilizing modern testing techniques and various analytical chemical procedures. Although the tests performed are well established, their applica...

R. A. Sasse

1985-01-01

77

A high performance nano-structure conductive coating on a Crofer22APU alloy fabricated by a novel spinel powder reduction coating technique  

Microsoft Academic Search

A nano-structure conductive coating was fabricated on a Crofer22APU alloy interconnect by an original coating strategy using Mn0.9Y0.1Co2O4 (MYC) novel spinel nanocrystalline powder. A unique treatment method by which the spinel powder was reduced was used to prepare the green coating. The resulting coating was about 12?m in thickness, and was composed of MYC nanocrystalline with an average particle size

Xianshuang Xin; Shaorong Wang; Qingshan Zhu; Yanjie Xu; Tinglian Wen

2010-01-01

78

In vitro and in vivo evaluations of ketoprofen extended release pellets prepared using powder layering technique in a rotary centrifugal granulator.  

PubMed

In the present study, an extended release pellet dosage form of ketoprofen was prepared using powder layering technique. A combination of ethyl cellulose (45 cps) and shellac polymers was used as a binder (12% w/w polymer) during drug layering and an extended release coating (1:3 ratio at 2%, 4% and 7% w/w polymer) within the same apparatus. The coated pellets were characterized for sphericity, Hardness-Friability Index, and drug content, and also underwent scanning electron microscopy. In vitro dissolution was performed in 900 mL of phosphate buffer (pH 6.8) using paddle apparatus at 100 rpm. Ethyl cellulose and shellac when used as binders during drug loading did not extend ketoprofen release beyond 3 h. However, coating of the drug loaded pellets using ethyl cellulose and shellac resulted in an extended release profile of about 10 h. Using Higuchi's model and the Korsmeyer equation, the drug release mechanism from the pellets was found to be an anomalous type involving diffusion and erosion. Scanning electron microscopy was used to visualize the pellet morphology and drug release mechanism during dissolution testing. In vivo evaluations of the extended release pellets in rats indicated a significant increase in the time to reach maximum concentration (t(max)) and extent of absorption (AUC(0-?)) compared to the ketoprofen immediate release tablet blend dispersed and dosed. In conclusion, extended release pellets of ketoprofen could perform therapeutically better than conventional dosage forms, leading to improved efficacy for a prolonged period. PMID:21811920

Pai, Raveendra; Kohli, Kanchan; Jain, Gaurav; Srivastava, Birendra

2011-08-03

79

Powder metallurgy of superalloys  

SciTech Connect

Powder metallurgy superalloys were developed in the mid-1960's when stronger aircraft turbine disk materials were needed. Their characteristics of greatly reduced segregation, better hot-workability, improved mechanical properties, and cost-effective manufacturing processes made P/M superalloys highly desirable in high-temperature applications. This book deals with prealloyed superalloys including rapidly solidified (RSR) alloys and oxide-dispersion strengthened alloys, as well as processing techniques such as sintering, hot isostatic pressing, extrusion, and isothermal forging. The large range of microstructures possible are correlated with mechanical properties at intermediate and elevated temperatures. Methods of powder production and consolidation are detailed, as are thermomechanical processing principles by which different microstructures can be created. Non-destructive testing techniques, and problems and advances relating to mechanical properties and processing are also covered.

Gessinger, G.H.

1984-01-01

80

Powder metallurgy of superalloys  

Microsoft Academic Search

Powder metallurgy superalloys were developed in the mid-1960's when stronger aircraft turbine disk materials were needed. Their characteristics of greatly reduced segregation, better hot-workability, improved mechanical properties, and cost-effective manufacturing processes made P\\/M superalloys highly desirable in high-temperature applications. This book deals with prealloyed superalloys including rapidly solidified (RSR) alloys and oxide-dispersion strengthened alloys, as well as processing techniques such

Gessinger

1984-01-01

81

New combustion synthesis technique for the production of (InxGa1- x)2O3 powders: Hydrazine\\/metal nitrate method  

Microsoft Academic Search

A new low-temperature method to produce (InxGa1?x)2O3 (x 4 0.1, 0.2, and 0.3) powders with high purity, high chemical homogeneity and improved crystallinity in the as-synthesized state has been developed. This procedure produced finely divided powders through an exothermic reaction between the precursors. The process starts with aqueous solutions of In(NO3)3 and Ga(NO3)3 as the precursors and hydrazine as the

R. Garca; G. A. Hirata; J. McKittrick

2001-01-01

82

METAL INJECTION MOLDING OF ULTRAFINE 316L STAINLESS STEEL POWDERS  

Microsoft Academic Search

Stainless steels have become one of the most popular materials for the metal injection molding (MIM) process. Due to the poor yield of fine particles in powder production, the cost of relatively fine powders was extremely high. With improvements in the powder processing technique, relatively fine stainless steel powders (mean 10 to 15 micrometers) became available during the 1990's, resulting

Animesh Bose; Takafumi Yoshida; Hisataka Toyoshima

2007-01-01

83

Measurement of agglomerate strength distributions in agglomerated powders  

Microsoft Academic Search

A new technique for measuring the strength distributions of powder agglomerates involves the use of a calibrated ultrasonic sound field. Agglomerate strength distributions were measured for a variety of yttria and yttria-stabilized zirconia powders. Different preparation methods were used to obtain powders containing agglomerates with different characteristics. Special yttria powders containing agglomerates of 0.1 microns, spherical, monosize spheres were also

M. Ciftcioglu

1987-01-01

84

AI-Li/SiCp composites and Ti-AI alloy powders and coatings prepared by a plasma spray atomization (PSA) technique  

NASA Astrophysics Data System (ADS)

There has been increasing use of Al-Li alloys in the aerospace industry, due mainly to the low density and high elastic modulus of this material. However, the problem of low ductility and fracture toughness of this material has limited its present application to only weight- and stiffness-critical components. Development of Al-Li/ceramic composites is currently being investigated to enhance the service capabilities of this material. The Ti-Al alloy is also of interest to aerospace-type applications, engine components in particular, due to its attractive high-temperature properties. Preparation of fine powders by plasma melting of composite feedstock and coatings formed by plasma spraying was carried out to examine the effect of spray parameters on the microstructure and properties of these materials. Characterization of the powders and coatings was performed using the scanning electron microscope and image analyzer. Examination of the plasma-sprayed powders and coatings has shown that in the Al-Li/SiC composite there is melting of both materials to form a single composite particle. The SiC reinforcement was in the submicron range and contributed to additional strengthening of the composite body, which was formed by a cold isostatic press and consolidated by hot extrusion or hot forging processes. The plasma-sprayed Ti-Al powder showed four categories of microstructures: featureless, dendritic, cellular, and martensite-like.

Khor, K. A.; Boey, F. Y. C.; Murakoshi, Y.; Sano, T.

1994-06-01

85

High resolution powder blast micromachining  

Microsoft Academic Search

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

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

2000-01-01

86

A co-precipitation technique to prepare BiNbO{sub 4}, MgTiO{sub 3} and Mg{sub 4}Ta{sub 2}O{sub 9} powders  

SciTech Connect

A simple co-precipitation technique has been used successfully for the preparation of pure, ultrafine, single phase BiNbO{sub 4} (BN), MgTiO{sub 3} and Mg{sub 4}Ta{sub 2}O{sub 9}. An aqueous sodium hydroxide or ammonium hydroxide and ammonium carbonate solution was used to precipitate these cations as hydroxides and carbonates simultaneously under basic conditions. These precursors on heating at 750 deg. C, produce the respective powders. For comparison, these compounds were also prepared by the traditional solid state method. The phase purity and lattice parameters were studied by powder X-ray diffraction (XRD). Particle size and morphology was studied by transmission electron spectroscopy (TEM)

Gaikwad, A.B. [Center for Materials Characterization, National Chemical Laboratory, Pune 411008 (India); Navale, S.C. [Physical and Materials Chemistry Division, National Chemical Laboratory, Pune 411008 (India); Samuel, V. [Catalysis Division, National Chemical Laboratory, Pune 411008 (India); Murugan, A.V. [Centre for Materials for Electronics Technology (C-MET), Department of Information Technology, Government of India, Dr. Homibhabha Road, Panchawati, Pune 411008 (India); Ravi, V. [Physical and Materials Chemistry Division, National Chemical Laboratory, Pune 411008 (India)]. E-mail: ravi@ems.ncl.res.in

2006-02-02

87

Measurement of Agglomerate Strength Distributions in Agglomerated Powders.  

National Technical Information Service (NTIS)

A new technique for measuring the strength distributions of powder agglomerates involves the use of a calibrated ultrasonic sound field. Agglomerate strength distributions were measured for a variety of yttria and yttria-stabilized zirconia powders. Diffe...

M. Ciftcioglu

1987-01-01

88

Mask materials for powder blasting  

NASA Astrophysics Data System (ADS)

Powder blasting, or abrasive jet machining (AJM), is a technique in which a particle jet is directed towards a target for mechanical material removal. It is a fast, cheap and accurate directional etch technique for brittle materials such as glass, silicon and ceramics. The particle jet (which expands to about 1 cm in diameter) can be optimized for etching, while the mask defines the small and complex structures. The quality of the mask influences the performance of powder blasting. In this study we tested and compared several mask types and added a new one: electroplated copper. The latter combines a highly resistant mask material for powder blasting with the high-resolution capabilities of lithography, which makes it possible to obtain an accurate pattern transfer and small feature sizes (<50 m).

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

2000-06-01

89

Composite metal foams processed through powder metallurgy  

Microsoft Academic Search

A new closed cell composite metal foam has been produced using a powder metallurgy technique. The composite foams are processed by filling the vacancies between densely packed steel hollow spheres with steel powder and sintering them into a solid cellular structure. Three sets of samples have been processed, two of carbon steel and one of stainless steel. The relative densities

B. P. Neville; A. Rabiei

2008-01-01

90

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

91

Characterization of INCONEL alloy MA 6000 powder  

NASA Astrophysics Data System (ADS)

Mechanically alloyed powders of INCONEL* alloy MA 6000 have been characterized in order to understand the mechanical alloying process. Various analytical techniques including transmission electron microscopy, X-ray diffraction, electron microprobe analysis, and Auger electron spectroscopy were used to reveal the microstructural changes, chemical homogeneity, degree of mechanical working, and surface chemistry of powders during the powder processing. The current investigation has brought about a better understanding of the basic mechanism of the mechanical alloying process as well as a guideline for quality control of mechanically alloyed powder.

Kang, S. K.; Benn, R. C.

1987-06-01

92

Rapid breakdown anodization technique for the synthesis of high aspect ratio and high surface area anatase TiO{sub 2} nanotube powders  

SciTech Connect

Clusters of high aspect ratio, high surface area anatase-TiO{sub 2} nanotubes with a typical nanotube outer diameter of about 18 nm, wall thickness of approximately 5 nm and length of 5-10 {mu}m were synthesized, in powder form, by breakdown anodization of Ti foils in 0.1 M perchloric acid, at 10 V (299 K) and 20 V ({approx}275 and 299 K). The surface area, morphology, structure and band gap were determined from Brunauer Emmet Teller method, field emmission scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Raman, photoluminescence and diffuse reflectance spectroscopic studies. The tubular morphology and anatase phase were found to be stable up to 773 K and above 773 K anatase phase gradually transformed to rutile phase with disintegration of tubular morphology. At 973 K, complete transformation to rutile phase and disintegration of tubular morphology were observed. The band gap of the as prepared and the annealed samples varied from 3.07 to 2.95 eV with increase in annealing temperature as inferred from photoluminescence and diffuse reflectance studies. -- Graphical abstract: Display Omitted Research highlights: {yields} High aspect ratio anatase-titania nanotube powders were synthesized electrochemically. {yields} The surface area of the nanotubes were much higher than those reported. {yields} The annealing temperature limit for maintaining tubular morphology was established. {yields} The photoluminiscence spectroscopy reflected the presence of defects, annealing of defects and phase transformation. {yields} The nanotubes were of {approx}5 nm wall thickness as revealed by TEM studies.

Antony, Rajini P. [Thin Films and Coatings Section, Surface and Nanoscience Division, Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102, Tamil Nadu (India); Mathews, Tom, E-mail: tom@igcar.gov.i [Thin Films and Coatings Section, Surface and Nanoscience Division, Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102, Tamil Nadu (India); Dasgupta, Arup [Physical Metallurgy Division, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102, Tamil Nadu (India); Dash, S.; Tyagi, A.K. [Thin Films and Coatings Section, Surface and Nanoscience Division, Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102, Tamil Nadu (India); Raj, Baldev [Thin Films and Coatings Section, Surface and Nanoscience Division, Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102, Tamil Nadu (India); Physical Metallurgy Division, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102, Tamil Nadu (India)

2011-03-15

93

TWENTIETH ANNUAL CONFERENCE OF INDIAN NUCLEAR SOCIETY (INSAC-2009): THEME: MATERIALS AND MANUFACTURINGIN NUCLEAR INDUSTRY 4-6 JANUARY 2010, THE CONVENTION CENTRE, CHENNAI TRADE CENTRE, CHENNAI, INDIA Synthesis and sintering of nanosize Li 2 TiO 3 ceramic breeder powder prepared by autocombustion technique  

Microsoft Academic Search

In the present report we prepare nanosize Li2TiO3 breeder powder by auto-combustion technique using cheaper source of Ti (e.g. TiO2) as the precursor material avoiding costly precursor like TiCl4 or Ti-isopropoxide. We find that by controlling the citrate nitrate ratio, the phase formation takes place during the autocombustion stage. The specific surface area of the synthesized powder is 35 m

A. Bhabani; Sankar Sahu; B. S. Bhatacharyya; C. P. Chaudhuri; D. R. Mazumder

2010-01-01

94

Preparing Copper Powder from Cemented Copper.  

National Technical Information Service (NTIS)

Techniques were developed for preparing metallurgical-grade copper powder from industrially produced cement copper. Flotation was used for rejecting discrete gangue particles, acid leaching to remove residual iron and aluminum, hydrogen reduction to elimi...

J. K. Winter L. G. Evans R. D. Groves

1971-01-01

95

Determination of pore size of filter materials from nonspherical powders  

Microsoft Academic Search

1.For porous materials from nonspherical metal powders, the order of pore sizes determined by different techniques is Dmicr > Dmax> Dhydr.2.The tortuosity coefficient of the pore passages of materials produced by sintering fine powder with a filler increases with increase in the particle size of the filler.3.For a porous material from nonspherical powder, filtration fineness (the maximum size of escaping

S. M. Solonin; N. P. Sleptsova; L. I. Chernyshev

1971-01-01

96

Compaction of amorphous ferromagnetic metal powders. Final report  

Microsoft Academic Search

The attractive magnetic properties of certain amorphous metal powders might be exploited in the electrical industry if the powders could be consolidated into relatively dense compacts. This work attempted to produce integral bodies of an amorphous powder using explosive compaction techniques. A disk-shaped compact 2.5 cm in diameter by 1 cm thick having a relative measured density of 91% was

Caligiuri

1982-01-01

97

Metal oxide powder synthesized with amorphous metal chelates  

Microsoft Academic Search

Chelate powder consisting of amorphous particles was synthesized through the process in which the droplet of the chelate solution is dried in the gas phase and solidified in a moment using a splay-dry technique. To investigate the advantage of the use of amorphous chelate powder in the processing of metal oxide powder, this study provides following two routes: a conventional

H. Saitoh; R. Satoh; A. Nakamura; N. Nambu; S. Ohshio

2002-01-01

98

Suspension plasma spraying for hydroxyapatite powder preparation by RF plasma  

Microsoft Academic Search

Numerous techniques have been developed to synthesize ceramic powders with improved physical and chemical characteristics. This paper describes a new process called suspension plasma spraying (SPS), based on the use of radio frequency (RF) plasma technology. The objective of SPS is to prepare dense and spherical powders from a suspension of fine (<10 pm) or even ultrafine (<100 nm) powders.

Etienne Bouyer; F. Gitzhofer; M. I. Boulos

1997-01-01

99

Surface Modification of EDMed Surface with Powder Mixed Fluid  

Microsoft Academic Search

The EDMed surface with metal powder mixed fluid has smaller surface roughness and higher resistance to corrosion because of the diffusion of electrode and\\/or powder materials into the machined surface. In this study, a new surface modification technique is proposed to obtain high surface wear resistance using EDM with powder mixed fluid. Firstly, a coating application of nickel layer on

Y. Uno; A. Okada; S. Cetin

100

Electroless nickelphosphorus plating on graphite powder  

Microsoft Academic Search

Electroless deposition technique was used to coat NiP on graphite particles with high deposition rate and bath stability by activating the graphite powder in a furnace at 380C for 1h. The effect of plating time, size of the powder and weight of the powder were studied. It was found that by a simple and controlled plating method a uniform and

M. Palaniappa; G. Veera Babu; K. Balasubramanian

2007-01-01

101

Improving powder flow properties of a cohesive lactose monohydrate powder by intensive mechanical dry coating.  

PubMed

The objective of this study was to improve the cohesive lactose powder flowability. A cohesive lactose monohydrate powder was processed in either a tumbling blender or an intensive mechanical processor with either magnesium stearate or fumed silica. No substantial changes in particle size were detected by laser diffraction following either treatment. The untreated lactose sample exhibited very poor powder flow. Only limited improvements in powder flowability were indicated after the tumbling blending, intensive mechanical processing with the fumed silica or without additives. However, the intensive mechanical processing of the lactose sample with magnesium stearate demonstrated exceptionally large increases in both poured and tapped density as well as notable improvements in all powder flowability indicators examined. Our findings support the use of intensive mechanical processing technique as an effective method to coat cohesive pharmaceutical powders with selected additives, modify the surface nature of the particles, reduce the interparticle cohesive forces and hence improve powder flowability. The subtle differences in powder flow behaviour of lactose samples between the untreated and tumbling blended powders with magnesium stearate were only detected by the powder rheometer using its dynamic mode, indicating its potential advantages over traditional powder flow characterisation approaches. PMID:19795479

Zhou, Qi; Armstrong, Brian; Larson, Ian; Stewart, Peter J; Morton, David A V

2010-02-01

102

Talcum Powder and Cancer  

MedlinePLUS

... is talcum powder? Talcum powder is made from talc, a mineral made up mainly of the elements ... other consumer products. In its natural form, some talc may contain asbestos, a substance known to cause ...

103

Precision powder feeder  

DOEpatents

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

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

2001-07-10

104

Smokeless Powder Manufacture.  

National Technical Information Service (NTIS)

The smokeless powder propellants are suitable for propelling military rockets and actuating jet devices such as assisted takeoff motors for airplanes. Smokeless powder granules are introduced into a container, pressure is placed on the granules and nonvol...

D. H. Black

1965-01-01

105

Atomized copper powders  

Microsoft Academic Search

For the first time in the Soviet Union pilot-plant batches of copper powder have been produced by the method of atomization of melts with water under high pressure. The powder produced is characterized by increased apparent density and flowability. The best compressibility (26 tons\\/cm2) is exhibited by the powder after annealing. The compressibility of the powder in the as-atomized condition

A. N. Karibyan; A. B. Medvedovskii; V. A. Belyakov; N. S. Sarkisyan; N. G. Dyuzhakova; O. S. Nichiporenko; V. T. Aivazyan; V. P. Poteshkina; Yu. I. Naida

1981-01-01

106

An improved method for shock consolidation of powders  

Microsoft Academic Search

A technique for shock consolidation of powders was developed. This technique uses the cylindrical geometry with two co-axial tubes. The powder is contained in the internal tube. The external tube is surrounded by the explosive charge, which is detonated at one end; this external tube acts as a flyer tube, impacting the internal tube. This technique generates pressures in the

M. A. MEYERS; S. L. WANG

1988-01-01

107

Explosive compaction of Nd-Fe-B powder  

Microsoft Academic Search

The explosive compaction technique has been applied to consolidate Nd-Fe-B amorphous powder, and the microstructure and magnetic properties of the compacts have been investigated. Explosive compaction was performed using an improved direct method. Nd-Fe-B amorphous powder was filled in the upper part of a metal sleeve and SiC powder was filled up to a lower part of the powder to

S Ando; Y Mine; K Takashima; S Itoh; H Tonda

1999-01-01

108

Differences in estimates of size distribution of beryllium powder materials using phase contrast microscopy, scanning electron microscopy, and liquid suspension counter techniques  

Microsoft Academic Search

Accurate characterization of the physicochemical properties of aerosols generated for inhalation toxicology studies is essential for obtaining meaningful results. Great emphasis must also be placed on characterizing particle properties of materials as administered in inhalation studies. Thus, research is needed to identify a suite of techniques capable of characterizing the multiple particle properties (i.e., size, mass, surface area, number) of

Aleksandr B Stefaniak; Mark D Hoover; Robert M Dickerson; Gregory A Day; Patrick N Breysse; Ronald C Scripsick

2007-01-01

109

Thermal analysis of black powder  

Microsoft Academic Search

While there is abundant literature describing the factors affecting the performance and the mechanical sensitivity of black\\u000a powder, only a few papers are devoted to its thermal properties. Previous work indicated that no exothermic reactions were\\u000a observed below 300C in an inert gas environment. In the present work a variety of thermal techniques (DSC, TG, simultaneous\\u000a TG-DTA-FTIR-MS, ARC, HFC) has

R. Turcotte; R. C. Fouchard; A.-M. Turcotte; D. E. G. Jones

2003-01-01

110

Metallography of powder metallurgy materials  

SciTech Connect

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

Lawley, Alan; Murphy, Thomas F

2003-12-15

111

Consolidation by electrical resistance sintering of Ti powder  

Microsoft Academic Search

In this study, commercially pure Ti powder was consolidated by the electrical resistance sintering (ERS) technique. This consolidation\\u000a technique consists of the application of pressure (around 100MPa) to a powder mass at the same time that the powder is heated\\u000a by the passage of an electric current of high intensity (around 10kA), low voltage (around 5V) and a frequency of

J. M. MontesJ; J. A. Rodrguez; F. G. Cuevas; J. Cintas

2011-01-01

112

Measurement of agglomerate strength distributions in agglomerated powders  

NASA Astrophysics Data System (ADS)

A new technique for measuring the strength distributions of powder agglomerates involves the use of a calibrated ultrasonic sound field. Agglomerate strength distributions were measured for a variety of yttria and yttria-stabilized zirconia powders. Different preparation methods were used to obtain powders containing agglomerates with different characteristics. Special yttria powders containing agglomerates of 0.1 microns, spherical, monosize spheres were also prepared. BET surface area, tap density, pressed density, compaction curves, and mercury intrusion curves were also obtained. The powders were pressed and sintered, and the sintered density measured for each pellet. Smooth curves could be drawn when agglomerate strength was plotted against sintered density; the sintered density of the powders also could be ranked directly according to the strength of the agglomerates in each powder. Except for the model yttria powders containing monosize spherical particles, there was no correlation between sintered density and any other measured powder parameter. For this model powder, most of measured powder parameters correlated directly with sintered density, in almost textbook fashion. It was also possible, using these model powders, to isolate the effect of agglomerate strength on sintered density by holding all other powder characteristics constant.

Ciftcioglu, M.

1987-08-01

113

Reactive synthesis of titanium matrix composite powders  

Microsoft Academic Search

Mechanical activation of materials has emerged as a promising alternative to conventional thermally activated processes. The present work deals with the attrition of titanium powders to produce TiTiO2 composite powders by reactive milling (RM). The phase transformation\\/new phases formed during the course of milling have been characterized by sophisticated techniques such as X-ray diffraction (XRD), electron spectroscopy for chemical analysis

P. B Joshi; G. R Marathe; N. S. S Murti; V. K Kaushik; P Ramakrishnan

2002-01-01

114

Which Powder is It?  

NSDL National Science Digital Library

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

Sciencenter

2012-06-26

115

Air permeability of powder: a potential tool for Dry Powder Inhaler formulation development.  

PubMed

Dry Powder Inhalers have drawn great attention from pharmaceutical scientists in recent years in particular those consisting of low-dose micronized drug particles associated with larger carrier particles and called interactive mixtures. However, there is little understanding of the relation between bulk powder properties such as powder structure and its aerodynamic dispersion performance. The aim of this work was to develop a simple method to measure the air permeability of interactive mixtures used in Dry Powder Inhalers by using Blaine's apparatus--a compendial permeameter and to relate it to the aerodynamic behaviour. The study was done with fluticasone propionate and terbutaline sulphate as drug models that were blended with several lactoses having different particle size distribution thus containing different percentages of fine particle lactose. The quality of the blends was examined by analysing the drug content uniformity. Aerodynamic evaluation of fine particle fraction was obtained using a Twin Stage Impinger. A linear correlation between a bulk property--air permeability of packed powder bed--and the fine particle fraction of drug was observed for the tested drugs. The air permeability reflects the quantity of the free particle fraction in the interparticulate spaces of powder bed that leads to fine particle fraction during fluidization in air flow. A theoretical approach was developed in order to link the air permeability of powder bed and drag force acting on powders during aerosolization process. The permeability technique developed in this study provides a potential tool for screening Dry Powder Inhaler formulations at the development stage. PMID:20854906

Le, V N P; Robins, E; Flament, M P

2010-09-18

116

The powder dilemma  

SciTech Connect

This article examines the high Tc powder market. Two types of suppliers are distinguished: large materials suppliers and small start-up superconductor firms. The author analyzes the role each is playing in the present market and discusses future possibilities for both. The problem of a lack of standards for high Tc powder is addressed.

Carlson, L

1989-01-01

117

Compaction of Titanium Powders  

Microsoft Academic Search

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 mum, <75 mum, and < 45 mum; two

Stephen J. Gerdemann; Paul D. Jablonski

2011-01-01

118

Sinterability of titanium powder  

Microsoft Academic Search

The sintering process of compacts from dispersed titanium powders (as well as from metal powders with easily reducible oxides) is accomplished in two stages a nonsteady stage with a high densification rate and a steady stage, whose rate is determined by volume diffusion. The low values of energy of activation for densification in the first stage of sintering may

D. S. Arensburger

1970-01-01

119

Ceramic powder synthesis in supercritical fluids  

SciTech Connect

Gas-phase processing plays an important role in the commercial production of a number of ceramic powders. These include titanium dioxide, carbon black, zinc oxide, and silicon dioxide. The total annual output of these materials is on the order of 2 million tons. The physical processes involved in gas-phase synthesis are typical of those involved in solution -phase synthesis: chemical reaction kinetics, mass transfer, nucleation, coagulation, and condensation. This report focuses on the work done under a Laboratory-Directed Research and Development (LDRD) project that explored the use of various high pressure techniques for ceramic powder synthesis. Under this project, two approaches were taken. First, a continuous flow, high pressure water reactor was built and studied for powder synthesis. And second, a supercritical carbon dioxide static reactor, which was used in conjunction with surfactants, was built and used to generate oxide powders.

Adkins, C.L.J.; Russick, E.M.; Cesarano, J; Tadros, M.E.; Voigt, J.A.

1996-04-01

120

Strain-enhanced sintering of iron powders  

NASA Astrophysics Data System (ADS)

Sintering of ball-milled and un-milled Fe powders has been investigated using dilatometry, X-ray, density, and positron annihilation techniques. A considerable sintering enhancement is found in milled powders showing apparent activation energies that range between 0.44 and 0.80 eV/at. The positron annihilation results, combined with the evolution of the shrinkage rate with sintering temperature, indicate generation of lattice defects during the sintering process of milled and un-milled powders. The sintering enhancement is attributed to pipe diffusion along the core of moving dislocations in the presence of the vacancy excess produced by plastic deformation. Positron annihilation results do not reveal the presence of sintering-induced defects in un-milled powders sintered above 1200 K, the apparent activation energy being in good agreement with that for grain-boundary diffusion in ?-Fe.

Amador, D. R.; Monge, M. A.; Torralba, J. M.; Pareja, R.

2005-02-01

121

Mechanochemical Synthesis of Single Phase Nanocrystalline Forsterite Powder  

NASA Astrophysics Data System (ADS)

Pure nanocrystalline forsterite (Mg2SiO4) powder was successfully synthesized by mechanochemical route and subsequent annealing. The starting materials were talc (Mg3Si4 O10(OH)2) and magnesium carbonate (MgCO3) powders. To produce forsterite powder, first talc and magnesium carbonate powders were calcined at 1200C for 1 h and 700C for 2 h, respectively. After that the mixture of obtained powders was milled by a planetary ball mill, and then annealed at 1000C and 1200C for 1 h. Thermogravimetric (TG) analysis, X-ray diffraction (XRD), and scanning electron microscopy (SEM) techniques were utilized to characterize the initial and prepared powders. The results showed that a single phase nanocrystalline forsterite powder with a crystallite size of 49 nm was obtained after 40 h milling and subsequent annealing at 1000C for 1 h.

Tavangarian, F.; Emadi, R.

122

Transparent zinc sulfide processed from nanocrystalline powders  

NASA Astrophysics Data System (ADS)

Nanocerox produces oxide nanopowders via flame spray pyrolysis that have proven effective in the processing of a host of high quality optical ceramic materials. In order to produce LWIR windows to compete with ZnS, however, oxide materials are not suitable. Nanocerox has therefore developed aqueous synthesis techniques for the production of zinc sulfide nanopowders. The proprietary processing technique allows control of primary particle size, high purity, low levels of agglomeration, and cost effective synthesis. Crystallinity, particle size, and purity of the powders will be presented. Characterization of parts fabricated from these powders via sinter/HIP processing will also be discussed, including optical performance and microstructural characterization.

Gao, De; Stefanik, Todd S.

2013-06-01

123

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 ?m, <75 ?m, and < 45 ?m; two different sizes of a hydride-dehydride [HDH] <75 ?m and < 45 ?m; an atomized powder; a commercially pure [CP] Ti powder from International Titanium Powder [ITP]; and a Ti 6 4 alloy powder) were cold pressed in a single-acting die instrumented to collect stress and deformation data during compaction. From these data, the density of each compact was calculated and then plotted as a function of pressure. The results show that densification of all the powders, regardless of particle size, shape, or chemistry, can be modeled accurately as the sum of an initial density plus the sum of a rearrangement term and a work-hardening term. These last two terms are found to be a function of applied pressure and take the form of an exponential rise.

Stephen J. Gerdemann; Paul D. Jablonski

2010-11-01

124

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

125

Compaction of Titanium Powders  

NASA Astrophysics Data System (ADS)

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

Gerdemann, Stephen J.; Jablonski, Paul D.

2011-05-01

126

PREPARATION OF METAL POWDER COMPACTS PRIOR TO PRESSING  

DOEpatents

A method of fabricating uranium by a powder metallurgical technique is described. It consists in introducing powdered uranium hydride into a receptacle shaped to coincide with the coatour of the die cavity and heating the hydride so that it decomposes to uranium metal. The metal particles cohere in the shapw of the receptacle and thereafter the prefurmed metal powder is pressed and sintered to obtain a dense compact.

Mansfield, H.

1958-08-26

127

Structural characterization of rapidly solidified white cast iron powders  

Microsoft Academic Search

Three white cast iron alloy powders (2.4% C, 3.0% C, and 3.0% C + 1.5% Cr) manufactured by a rapid solidification processing technique were investigated. It was found that the microstructures of all three alloy powders were similar. The primary constituent of these powders was found to be retained austenite. Only small amounts of carbide and martensite were found in

Lawrence E. Eiselstein; Oscar A. Ruano; Oleg D. Sherby

1983-01-01

128

Determination of the Diffusion by the Technique of Change of Resistance in the System Copper-Nickel Pressed Powders (Vclidzhennya Vnurishn'oi Difuzii za Metodom Electrovidnosti v Sistemakh z Presovanikh Poroshkiv Mid'-Nikel).  

National Technical Information Service (NTIS)

Pure copper and nickel powders were pressed at pressures ranging up to 12000 atmospheres and annealed at temperatures up to high as 800C for different lengths of time. Electrical resistivity measurements were recorded under the different variables in the ...

S. D. Gertsriken A. A. Shatalov

1975-01-01

129

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

Microsoft Academic Search

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

C. Q. Ning; Y. Zhou

2002-01-01

130

Super Chi Flush Powder  

Center for Drug Evaluation (CDER)

Text Version... Chi Flush Powder Super Chi Flush fights the toughest clogs in the body slowly opening up the blockades which hindered the flow of Chi energy. ... More results from www.fda.gov/downloads/drugs/guidancecomplianceregulatoryinformation

131

Aluminum powder metallurgy processing.  

National Technical Information Service (NTIS)

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 a...

J. F. Flumerfelt

1999-01-01

132

Compaction of Titanium Powders  

Microsoft Academic Search

Accurate modeling of powder densification has been an area of active research for more than 60years. The earliest efforts\\u000a were focused on linearization of the data because computers were not readily available to assist with curve-fitting methods.\\u000a In this work, eight different titanium powders (three different sizes of sponge fines ?m, ?m, and ?m; two different sizes of a hydride-dehydride

Stephen J. Gerdemann; Paul D. Jablonski

2011-01-01

133

Shock-Wave Consolidation of Nanostructured Bismuth Telluride Powders  

NASA Astrophysics Data System (ADS)

Nanostructured thermoelectric powders can be produced using a variety of techniques. However, it is very challenging to build a bulk material from these nanopowders without losing the nanostructure. In the present work, nanostructured powders of the bismuth telluride alloy system are obtained in kilogram quantities via a gas atomization process. These powders are characterized using a variety of methods including scanning electron microscopy, transition electron microscopy, and x-ray diffraction analysis. Then the powders are consolidated into a dense bulk material using a shock-wave consolidation technique whereby a nanopowder-containing tube is surrounded by explosives and then detonated. The resulting shock wave causes rapid fusing of the powders without the melt and subsequent grain growth of other techniques. We describe the test setup and consolidation results.

Beck, Jan; Alvarado, Manuel; Nemir, David; Nowell, Mathew; Murr, Lawrence; Prasad, Narasimha

2012-06-01

134

Powders for metal injection molding  

Microsoft Academic Search

Metal injection molding (MIM) uses powders which differ considerably from the ceramics powders used for ceramic injection molding. Metal powders are hardly available in the sub-micron ranges that are almost standard in ceramics. The reason for this lies in the ductility and reactivity of the metals which make it difficult and very expensive to produce fine powders. In this paper

T. Hartwig; G. Veltl; F. Petzoldt; H. Kunze; R. Scholl; B. Kieback

1998-01-01

135

Magnetic properties of dynamically compacted glassy metal powder cores  

Microsoft Academic Search

Dynamic compaction of glassy metal powder generally results in denser noncrystalline components than any other consolidation techniques. For example, a density of more than 90 % of the powder material can be achieved by dynamic compaction whereas it is typically about 70-80% for a component obtained by low temperature (below material's crystallization temperature) mechanical pressing. Bulk amorphous materials other than

R. Hasegawa; C. F. Cline

2008-01-01

136

Synthesis of Fine Titanium Powders Via Solution Route  

Microsoft Academic Search

Titanium, because of its light weight, high specific strength, corrosion resistance and biocompatibility is a demanding material for aerospace, chemical processing industries and biomedical applications. Titanium powders produced from titanium sponge, hydride-dehydride processes and by a variety of centrifugal atomisation techniques from liquid metals are relatively coarse. If fine size titanium powders can be produced, then the grain size in

S. AMARCHAND; T. R. RAMAMOHAN; P. RAMAKRISHNAN

2001-01-01

137

APPLICATION OF ULTRASONIC VIBRATION TO THE COMPACTION OF METAL POWDERS  

Microsoft Academic Search

Although powder metallurgy has lent impetus to the fabrication of high-; performance materials for nuclear reactor components, problems are associated ; with the technique; and the feasibility of applying ultrasonics as a means of ; improving and simplifying powder metallurgy procedures was investigated. ; Consideration was given to the possible influence of ultrasonic vibratory motion ; on mold filling, compact

J. G. Thomas; J. B. Jones

1958-01-01

138

Quality control of press-powders for engineering ceramics  

Microsoft Academic Search

The present paper deals with a study of the methods and means of evaluation of the macrostructure of granules, compactibility of press-powders, porosity, and green strength of the compacted products. The techniques developed successfully went through laboratory and industrial testing. The properties of press-powders depend on the properties of individual granules, which are aggregates of dispersed particles with binders, lubricants,

A. A. Polyakov

1982-01-01

139

What is "powder free"? Characterisation of powder aerosol produced during simulated use of powdered and powder free latex gloves  

PubMed Central

OBJECTIVESTo characterise the distribution of particle size and mass of glove powder aerosol released from powdered and powder free non-sterile latex gloves under controlled conditions.?METHODSGravimetric sampling and aerodynamic particle size analysis were performed during simulated use of gloves on a prosthetic hand in a chamber designed to minimise background particle concentrations.?RESULTSAerosol was detectable for both powdered and powder free gloves under both aggressive and non-aggressive handling conditions. Most of the particles detected had aerodynamic diameter less than 10m.?CONCLUSIONPowder free gloves were not entirely free of powder aerosol. Particles from both powdered and powder free gloves are sufficiently fine to penetrate into the thoracic region of the respiratory tract.???Keywords: latex gloves; glove powder; aerosol

Phillips, M; Meagher, C; Johnson, D

2001-01-01

140

Powder metal matrix composites: selection and processing  

Microsoft Academic Search

There has been growing interest in the last decade in the development of metal matrix composites (MMCs) for the aerospace industry because of their attractive physical and mechanical properties and enhanced elevated temperature capabilities. However, some of the fabrication techniques (e.g. using powder metallurgy) for this new class of MMCs are hampered by (i) the poor distribution of the reinforcements,

M. J Tan; X Zhang

1998-01-01

141

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

142

Freeze Drying: Potential for Powdered Nanoparticulate Product  

Microsoft Academic Search

Nanoparticles were prepared by using an emulsion solvent evaporation method. Further, the drying of an anti-cancer drug of proprietary nature (nanosized) was carried out by a freeze-drying technique to get a free-flowing powder. A systematic approach was developed to study the freeze-drying technique for polymeric nanoparticles. Initially, the freeze-thawing experiments were carried out with varying concentrations of cryoprotectants to screen

V. V. Patil; P. P. Dandekar; V. B. Patravale; B. N. Thorat

2010-01-01

143

Dry powder coating of pharmaceuticals: A review.  

PubMed

Over the last half century, film coating technology has evolved significantly in terms of compositions and manufacturing processes, allowing for greater functionality, flexibility and efficiency. Driven by a combination of cost considerations and functionality, a range of dry powder coating technologies have been developed in both academic and industrial settings. These technologies can be generally classified into three major types based on the layer formation process: liquid assisted, thermal adhesion and electrostatic. In addition to specific manufacturing processes that must be implemented to achieve the desired product attributes, many of these techniques also require the use of novel excipients and specific formulations to provide acceptable manufacturability. This review summarizes the current dry powder coating technologies and highlights their industrial applicability with publicly disclosed case studies. Commentary on the future directions of dry powder coating is also provided. PMID:23428881

Sauer, Dorothea; Cerea, Matteo; Dinunzio, James; McGinity, James

2013-02-18

144

X-ray resonant powder diffraction  

NASA Astrophysics Data System (ADS)

X-ray resonant diffraction can be applied in structural chemistry studies on powder samples. It enables an important limitation of powder diffraction to be overcome. This limitation is related to the low ability of powder diffraction to differentiate elements with close atomic numbers when they occupy the same or close crystallographic sites (mixed occupancy case) and also to discriminate cations with different valence states in different sites. However the resonant effect usually has a second order influence on the measured intensity. As a consequence, the efficiency of this method directly implies the need for excellent quality data collection and has generally been better assessed on elements present in single phase powder samples. In recent years, instrumental developments have been made in synchrotron radiation facilities which allow easier use of resonant powder diffraction for site-specific contrast and valence i.e. oxidation state analyses. Moreover, resonant contrast diffraction tools also have been proposed for better visualization of the anomalous effect both in direct and reciprocal space by using differences between electron density maps or diffraction patterns. Finally the potentialities of this technique for de novo structure solution on macromolecular systems are mentioned.

Palancher, H.; Bos, S.; Brar, J. F.; Margiolaki, I.; Hodeau, J. L.

2012-06-01

145

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

146

FORGING BERYLLIUM POWDER  

Microsoft Academic Search

The developments and results obtained in press forging beryllium powder ; are described. The forging method consists of using pressures in the range of ; 20,000 to 100,000 psi, sintering times from l sec to l min, and two temperature ; ranges of l600 and 1900 deg F. The description of a nonberyllium (stainless ; steel) can fabricated for holding

Cieslicki

1962-01-01

147

Morphologies of electrochemically formed copper powder particles and their dependence on the quantity of evolved hydrogen  

Microsoft Academic Search

Copper powder particles formed by electrolysis under different quantities of evolved hydrogen were analyzed using the scanning electron microscopy (SEM) technique. It was found that the structure of the powder particles strongly depended on the quantity of evolved hydrogen that is, two types of powder particles were formed, depending on the quantity of evolved hydrogen. One type of particle

N. D. Nikoli?; Lj. J. Pavlovi?; M. G. Pavlovi?; K. I. Popov

2008-01-01

148

Magnetothermal characteristics of amorphous Fe-Si-B powder produced by spark erosion  

Microsoft Academic Search

It has been found that the amorphous powder of a transition metal - metalloid alloy can be prepared by the spark erosion technique. The powder consists of roughly spherical particles whose diameters are ranging from 0.5 ?m to 30?m. The preparation procedure of the powder is described and its magnetothermal characteristics and the crystallization behaviours are discussed.

T. Yamaguchi; K. Narita

1977-01-01

149

Dynamic Magnetic Consolidation (DMC) Process for Powder Consolidation of Advanced Materials  

Microsoft Academic Search

This paper describes a novel rapid consolidation technique called Dynamic Magnetic Compaction (DMC) for consolidating advanced material powders. DMC utilizes pressures generated from pulsed electromagnetic fields to form net shape parts. The consolidation occurs rapidly in less than a millisecond via pressure wave propagation through the powders. Powders of different materials such as intermetallics, refractory alloys, ceramics, nano materials and

B. Chelluri

1994-01-01

150

Ultrasonic Characterization of Iron Powder Metallurgy Compacts during and after Compaction  

Microsoft Academic Search

Ultrasonic measurements in powder metallurgy (PM) compacts at various stages of production are presented both as a practical means of improving PM production and as a method of providing a fuller understanding of PM materials. Ultrasonic monitoring during powder compaction, a novel process instrumentation technique to follow powder densification, is reviewed. Measurements taken during the compaction of simple PM disk

Andrew Lerossignol Dawson; Jean Franois Bussire

1998-01-01

151

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

152

Thin Steel Strip from Powder.  

National Technical Information Service (NTIS)

A process for rolling thin strip is described which overcomes the disadvantages normally associated with powder rolling. Strip samples were made from both iron and stainless steel powders and an experimental plant has been built for continuous strip produ...

I. Davies W. M. Gibbon A. G. Harris

1969-01-01

153

Microstructural development of rapid solidification in Al-Si powder  

SciTech Connect

The microstructure and the gradient of microstructure that forms in rapidly solidificated powder were investigated for different sized particles. High pressure gas atomization solidification process has been used to produce a series of Al-Si alloys powders between 0.2 {mu}m to 150 {mu}m diameter at the eutectic composition (12.6 wt pct Si). This processing technique provides powders of different sizes which solidify under different conditions (i.e. interface velocity and interface undercooling), and thus give different microstructures inside the powders. The large size powder shows dendritic and eutectic microstructures. As the powder size becomes smaller, the predominant morphology changes from eutectic to dendritic to cellular. Microstructures were quantitatively characterized by using optical microscope and SEM techniques. The variation in eutectic spacing within the powders were measured and compared with the theoretical model to obtain interface undercooling, and growth rate during the solidification of a given droplet. Also, nucleation temperature, which controls microstructures in rapidly solidified fine powders, was estimated. A microstructural map which correlates the microstructure with particle size and processing parameters is developed.

Jin, F.

1995-11-01

154

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

155

Zirconium boride and tantalum carbide coatings sprayed by electrothermal explosion of powders  

Microsoft Academic Search

Refractory zirconium diboride and tantalum monocarbide ceramic powders were sprayed using an electrothermal explosion caused\\u000a by a high-voltage electric breakdown and large-current discharge heating. This spray technique was improved using a purpose-designed\\u000a powder container, which made it possible to melt the powder completely and accelerate it to impinge on substrates. The electrical\\u000a energy applied to the powder was estimated to

H. Tamura; M. Konoue; A. B. Sawaoka

1997-01-01

156

Screening mail for powders using terahertz technology  

NASA Astrophysics Data System (ADS)

Following the 2001 Anthrax letter attacks in the USA, there has been a continuing interest in techniques that can detect or identify so-called 'white powder' concealed in envelopes. Electromagnetic waves (wavelengths 100-500 ?m) in the terahertz frequency range penetrate paper and have short enough wavelengths to provide good resolution images; some materials also have spectroscopic signatures in the terahertz region. We report on an experimental study into the use of terahertz imaging and spectroscopy for mail screening. Spectroscopic signatures of target powders were measured and, using a specially designed test rig, a number of imaging methods based on reflection, transmission and scattering were investigated. It was found that, contrary to some previous reports, bacterial spores do not appear to have any strong spectroscopic signatures which would enable them to be identified. Imaging techniques based on reflection imaging and scattering are ineffective in this application, due to the similarities in optical properties between powders of interest and paper. However, transmission imaging using time-of-flight of terahertz pulses was found to be a very simple and sensitive method of detecting small quantities (25 mg) of powder, even in quite thick envelopes. An initial feasibility study indicates that this method could be used as the basis of a practical mail screening system.

Kemp, Mike

2011-10-01

157

Powder compaction with ultrasonic assistance  

Microsoft Academic Search

The compaction behaviour of a ceramic powder can be improved by ultrasonic assistance, only when ultrasounds are used at pressures lower than a critical value,PC. This critical pressure is connected with the limit of mobility of the powder grains under ultrasonic vibrations. Its value depends on the characteristics of the powder, as well as those of the ultrasounds: frequency, amplitude,

E. Emeruwa; J. Jarrige; J. Mexmain; M. Billy; K. Bouzouita

1990-01-01

158

Powder characteristics and coating conditions of fresh and reused polyester resins for electrostatic powder coating: powder recycling and loss prevention  

Microsoft Academic Search

Powder characteristics and coating conditions are significant factors in electrostatic powder coating. In this work, powder characteristics of the reused polyester resin or recycled powder particles in terms of shape, size, particle size distribution, moisture content, density, flowability, fluidity and chargeability were compared with those of fresh resin or as-received powder to consider powder recycling. The coating conditions for a

A. W. Lothongkum; R. Nonthapone; K. Seangkiatiyuth; W. Tanthapanichkoon

2007-01-01

159

Processing Studies of Powder Metallurgically-Produced High Temperature Alloys. Annual Progress Report, July 1, 1979-June 30, 1980.  

National Technical Information Service (NTIS)

One attraction processing route is based on the production of very fine, fully alloyed powders. Rapid quenching of fine powders via ultrasonic gas atomization also makes possible the utilization of multiple strengthening techniques. The proposed work incl...

N. J. Grant

1986-01-01

160

Silicon nitride/silicon carbide composite powders  

DOEpatents

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

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

1996-06-11

161

Surface dose measurement using TLD powder extrapolation  

SciTech Connect

Surface/near-surface dose measurements in therapeutic x-ray beams are important in determining the dose to the dermal and epidermal skin layers during radiation treatment. Accurate determination of the surface dose is a difficult but important task for proper treatment of patients. A new method of measuring surface dose in phantom through extrapolation of readings from various thicknesses of thermoluminescent dosimeter (TLD) powder has been developed and investigated. A device was designed, built, and tested that provides TLD powder thickness variation to a minimum thickness of 0.125 mm. Variations of the technique have been evaluated to optimize precision with consideration of procedural ease. Results of this study indicate that dose measurements (relative to D{sub max}) in regions of steep dose gradient in the beam axis direction are possible with a precision (2 standard deviations [SDs]) as good as {+-} 1.2% using the technique. The dosimeter was developed and evaluated using variation to the experimental method. A clinically practical procedure was determined, resulting in measured surface dose of 20.4 {+-} 2% of the D{sub max} dose for a 10 x 10 cm{sup 2}, 80-cm source-to-surface distance (SSD), Theratron 780 Cobalt-60 ({sup 60}C) beam. Results obtained with TLD powder extrapolation compare favorably to other methods presented in the literature. The TLD powder extrapolation tool has been used clinically at the Northwestern Ontario Regional Cancer Centre (NWORCC) to measure surface dose effects under a number of conditions. Results from these measurements are reported. The method appears to be a simple and economical tool for surface dose measurement, particularly for facilities with TLD powder measurement capabilities.

Rapley, P. [Regional Cancer Care, Thunder Bay Regional Health Sciences Centre, Thunder Bay, Ontario (Canada)]. E-mail: rapleyp@tbh.net

2006-10-01

162

Powder injection molding 440C stainless steel  

Microsoft Academic Search

In this work, the processing steps for producing 440C stainless steel parts by means of powder injection molding technique\\u000a were investigated. The molded specimens were debinded by solvent debinding followed by thermal debinding methods and were\\u000a sintered under vacuum atmosphere. Effective densification took place in the temperature range 1,2301,240C in the sintering.\\u000a After heat treatment, specimens sintered at 1,240C for

Duxin Li; Haitao Hou; Lianghua Liang; Kun Lee

2010-01-01

163

Fabricating sports equipment components via powder metallurgy  

Microsoft Academic Search

Powder metallurgy (P\\/M) offers a viable, cost-effective approach to fabricating sports and leisure equipment components. Both\\u000a complex, monolithic parts and parts produced from materials of quite different densities can be manufactured by this technique.\\u000a In the latter category, lightweight titanium and heavyweight tungsten can be used in combination to optimally distribute mass,\\u000a such as in golf club heads. Examples of

V. S. Moxson

2001-01-01

164

Laser diffraction particle size analysis of powders  

SciTech Connect

A Malvern Instruments Particle Sizer 3600Ec was purchased and used to determine the particle volume distribution for six reference materials and three process samples. These results were acceptable with respect to the accuracy and precision of the instrument, as well as the accuracy of our analytical technique. The instrument is currently employed as the sole means of determining sub-sieve particle size distributions for powders submitted to this laboratory. 1 ref., 5 figs., 5 tabs.

Hilbert, R.H.; Volesky, A.F.

1987-10-01

165

High strain rate deformation microstructures of stainless steel 316L by cold spraying and explosive powder compaction  

Microsoft Academic Search

Cold spraying is a new coating technique in which dense, tightly bonded coatings form only due to the high kinetic energy\\u000a of impinging particles of the spray powder. These particles are still in the solid state during impact. Explosive powder compaction\\u000a is a technique where powder is consolidated by a shock wave. In the shock front the powder is deformed

C. Borchers; T. Schmidt; F. Grtner; H. Kreye

2008-01-01

166

Headspace analysis of smokeless powders: Development of mass calibration methods using microdrop printing for chromatographic and ion mobility spectrometric detection  

Microsoft Academic Search

Smokeless powder additives are usually detected by their extraction from post-blast residues or unburned powder particles followed by analysis using chromatographic techniques. This work presents the first comprehensive study of the detection of the volatile and semi-volatile additives of smokeless powders using solid phase microextraction (SPME) as a sampling and pre-concentration technique. Seventy smokeless powders were studied using laboratory based

Monica Joshi-Kumar

2010-01-01

167

Headspace Analysis of Smokeless Powders: Development of Mass Calibration Methods using Microdrop Printing for Chromatographic and Ion Mobility Spectrometric Detection  

Microsoft Academic Search

Smokeless powder additives are usually detected by their extraction from post-blast residues or unburned powder particles followed by analysis using chromatographic techniques. This work presents the first comprehensive study of the detection of the volatile and semi-volatile additives of smokeless powders using solid phase microextraction (SPME) as a sampling and pre-concentration technique. Seventy smokeless powders were studied using laboratory based

Monica Joshi-Kumar

2010-01-01

168

Pourability Enhancement of PETN Explosive Powders  

SciTech Connect

Manufacture of precision detonators requires the pelletizing of very fine, organic, crystalline explosive powders. Production of pellets in automatic machines within critical dimensional and weight tolerances requires that the powders pour uniformly into die cavities. The pellets must be able to be initiated with low energy and have a predictable energy output. Modifications to needle-like crystalline PETN explosive powders to make them pourable were introduced by the application of about 80 A thick polymeric coatings to the individual crystals, followed by a controlled agglomeration into a spherical prill. Microencapsulation techniques provided the key to achieving the result using less than 0.5 wt. % coating (an order of magnitude less coating than in usual PBX systems). These coatings did not appreciably alter the energy required to initiate and significantly increased the strength of the pellets. A key point demonstrated, which may be translated to other applications, was that powders that exhibit performance based on physical characteristics could have their handling and strength properties tailored with little change in their primary function.

Vannet, M.D.; Ball, G.L.

1987-01-01

169

The effect of heat treatment on explosively compacted (Y?Ba?K?Cu?O) superconductive powders  

Microsoft Academic Search

A ceramic powder mixture corresponding to the stoichiometric ratio of YBa1.95K0.05Cu3Oy superconducting ceramic with 10% w\\/w Ag was heat treated at 950C for 3 h in flowing oxygen. The resultant superconducting powder was consolidated in a silver tube by the explosive compaction technique (pre-heat treated ceramic). The same fabrication technique, i.e. explosive compaction, was employed to the initial stoichiometric powder

A. G. Mamalis; I. Kotsis; G. Pantazopoulos; M. Enisz; A. Szalay; D. E. Manolakos

1997-01-01

170

Wet powder spraying of a cermet anode for a planar solid oxide fuel cell system  

NASA Astrophysics Data System (ADS)

The techniques that could be used for the adhesion of the anode into the electrolyte includes slurry painting and wet powder spraying. Wet powder spraying involves spraying a powder-carrier-binder mixture onto a surface by means of an air-brush. This technique enables the production of solid oxide fuel cell electrode coatings with uniform, controlled thickness regardless of shape and positioning of the electrolyte.

Sammes, N. M.; Brown, M. S.; Ratnaraj, R.

1994-08-01

171

Broadband electromagnetic wave absorbers prepared by grading magnetic powder density  

NASA Astrophysics Data System (ADS)

Resin compacts including iron-based magnetic powders were prepared using a centrifugal molding technique. Energy dispersive x-ray analyses demonstrated the formation of a concentration gradient of the magnetic powder in the resin compacts. The resultant concentration-graded resin compacts exhibited better broadband electromagnetic wave absorption than the homogeneous resin compacts prepared as a reference. This absorption ability was further enhanced by attaching a urethane foam plate to the absorber surface.

Itoh, Masahiro; Terada, Masao; Shogano, Fumiyoshi; Machida, Ken-Ichi

2010-09-01

172

Surface oxide debonding in field assisted powder sintering  

Microsoft Academic Search

Field activated sintering techniques (FAST) have been applied to two high-temperature powder materials: tungsten and NiAl. High and atomic resolution electron microscopy (HREM\\/ARM) of tungsten powder sintered via FAST showed essentially clean boundaries. Analytical transmission electron microscopy (TEM) of FAST sintered NiAl also showed boundaries free of surface oxide layer(s). However, small alumina precipitates were found at and near prior

K. R Anderson; J. R Groza; M Fendorf; C. J Echer

1999-01-01

173

Synthesis, formation and characterization of zirconium titanate (ZT) powders  

Microsoft Academic Search

Zirconium titanate (ZrTiO4) powders have been prepared and characterised by differential thermal analysis (DTA), X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX) techniques. The effect of calcination temperature, dwell time and heating\\/cooling rates on phase formation, morphology and particle size distribution of the powders are examined. The calcination temperature and dwell time have been found to have

S. Ananta; R. Tipakontitikul; T. Tunkasiri

2003-01-01

174

Sol-spray preparation, particulate characteristics, and sintering of alumina powders  

SciTech Connect

Fine alumina powders of spherical morphology and narrow particle-size distribution have been synthesized by a technique that uses precipitation/peptization/spray drying of boehmite sol prepared from aluminum nitrate. The spray-dried powder was further washed with solvents of varying polarities, such as acetone, isopropanol, and tert-butanol. This post-spray-drying treatment changed the powder`s particle-size distribution, morphology, density, and compaction characteristics. Microstructure, dielectric properties, and effect of post-treatment on the boehmite-sol-derived alumina powders in reducing agglomeration are discussed.

Varma, H.K.; Mani, T.V.; Damodaran, A.D.; Warrier, K.G.K. [Regional Research Lab., Trivandrum (India); Balachandran, U. [Argonne National Lab., IL (United States)

1993-07-01

175

Plasmasynthesized nano-aluminum powders  

Microsoft Academic Search

The plasma electro-condensation\\u000a process was used to synthesize nano-sized aluminum powders. Adding different\\u000a chemicals modified the physical and chemical properties of these powders.\\u000a To characterize the nano-sized powders, X-ray diffraction, TEM, BET analyses,\\u000a and simultaneous TG\\/DSC analyses were performed. TG\\/DSC analyses revealed\\u000a a dramatic degradation of the aluminum oxide layer after storage of the aluminum\\u000a powder in air for a

Alla Pivkina; D. Ivanov; Yu. Frolov; Svetlana Mudretsova; Anna Nickolskaya; J. Schoonman

2006-01-01

176

FTIR process monitoring of metal powder temperature and size distribution  

Microsoft Academic Search

We have developed in-situ infrared sensors for on-line measurements of particle size distributions and temperatures during the manufacture of metal powders produced by the supersonic inert gas molten atomization technique. The sensors are based on novel applications of Fourier transform infrared spectroscopy and advanced numerical analysis techniques based on sound physical models. We have demonstrated the ability to measure the

Peter A. Rosenthal; Joseph E. Cosgrove; John R. Haigis; James R. Markham; Peter R. Solomon; Stuart Farquharson; Philip W. Morrison; Stephen D. Ridder; Francis S. Biancaniello

1995-01-01

177

Dry powder aerosol delivery systems: current and future research directions.  

PubMed

Development of dry powder aerosol delivery system involves powder production, formulation, dispersion, delivery, and deposition of the powder aerosol in the airways. Insufficiency of conventional powder production by crystallization and milling has led to development of alternative techniques. Over the last decade, performance of powder formulations has been improved significantly through the use of engineered drug particles and excipient systems which are (i) of low aerodynamic diameters (being porous or of low particle density), and/or (ii) less cohesive and adhesive (via corrugated surfaces, low bulk density, reduced surface energy and particle interaction, hydrophobic additives, and fine carrier particles). Early insights into particle forces and surface energy that help explain the improvement have been provided by analytical techniques such as the atomic force microscopy (AFM) and inverse gas chromatography (IGC). Relative humidity is critical to the performance of dry powder inhaler (DPI) products via capillary force and electrostatic interaction. Electrostatic charge of different particle size fractions of an aerosol can now be measured using a modified electrical low-pressure impactor (ELPI). Compared with powders, much less work has been done on the inhaler devices at the fundamental level. Most recently, computational fluid dynamics has been applied to understand how the inhaler design (such as mouthpiece, grid structure, air inlet) affects powder dispersion. The USP throat is known to under-represent the oropharyngeal deposition of DPI aerosols. Studies using magnetic resonance imaging (MRI) model casts have been undertaken to explain the inter- and intra- subject variation in oropharyngeal deposition. Most of the lung deposition studies performed on commercial products did not allow a thorough understanding of the determinants affecting in vivo lung deposition. A more systematic approach would be necessary to build a useful database on the dependence of lung deposition on the breathing parameters, inhaler design, and powder formulation properties. PMID:16551211

Chan, Hak-Kim

2006-01-01

178

Simulation and Interpretation of ESR Powder Spectra of Some Gd exp 3+ Doped Perovskites.  

National Technical Information Service (NTIS)

The electron spin resonance technique is used to determine local symmetries of perovskites in powder form. Neutron diffraction techniques are used to investigate the overall structure of these compounds. Some model compounds have been doped with the param...

H. J. A. Koopmans

1983-01-01

179

Nonlinear optical activity of anhydrous and hydrated sodium p-nitrophenolate  

Microsoft Academic Search

Differently hydrated sodium p-nitrophenolate (NPNa) crystals were obtained while growing them from different solvents such as methanol and water. Thermal analysis and powder X-ray diffraction studies were carried out on these crystals. Kurtz powder SHG technique was used for qualitative assessment of their nonlinear optical (NLO) activity. From the detailed single-crystal X-ray diffraction studies it is established that NPNa has

S. Brahadeeswaran; V Venkataramanan; H. L Bhat

1999-01-01

180

Powder diffraction with spin polarized neutrons  

NASA Astrophysics Data System (ADS)

The polarized neutron diffraction (PND) and spherical neutron polarimetry (SNP) techniques are very powerful tools and provide arguably the most sensitive methods for determining magnetization distributions at all the positions of the chemical. However, they can only apply to single crystals. Because of the difficulties encountered in growing sufficiently large samples of molecular magnets, and the inability to measure efficiently powder samples and more specifically nanoscale systems, the PND and SNP techniques are inadequate for a number of highly interesting subjects. We present a new technique taking advantage of the recent progress of the polarized 3He neutron spin filters that should overcome these limitations and which we propose to call the 'flipping difference method'. We describe the measurement strategy, the data analysis technique and preliminary analysis of the results of the first measurements.

Lelivre-Berna, E.; Wills, A. S.; Bourgeat-Lami, E.; Dee, A.; Hansen, T.; Henry, P. F.; Poole, A.; Thomas, M.; Tonon, X.; Torregrossa, J.; Andersen, K. H.; Bordenave, F.; Jullien, D.; Mouveau, P.; Gurard, B.; Manzin, G.

2010-05-01

181

Alcohol interaction with zirconia powders  

Microsoft Academic Search

The mechanism by which alcohol washing of ceramic powders produces soft agglomerates has been investigated by studying the interaction of ethanol with hydrous ZrO powders using Fourier transform infrared (FTIR) spectroscopy. Unambiguous evidence of ethoxide formation has been found, which apparently prevents bond formation between adjacent particles and thus the formation of hard agglomerates.

Mary Sue Kaliszewski; Arthur H. Heuer

1990-01-01

182

Powdered resin for condensate polishing  

Microsoft Academic Search

Powdered resin systems have a lot to offer in the deionization of low TDS waters, as can be seen in the wide use of this process for the treatment of condensate in the electric power industry. I believe that as new ion-exchange resins are developed, we will see the powdered ion-exchange resin process adopted in other industries. At this time,

Richard Hetherington

1997-01-01

183

Mound powder loader, Mod 1  

SciTech Connect

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

Gress, A.V. Jr.

1985-08-21

184

Powder Dyeing Method for Cosmetics.  

National Technical Information Service (NTIS)

A powder dyeing method for cosmetics is described that is characterized in that dyes or pigments are dispersed in water or alcohol, the solution or dispersion is mixed with porous adsorbant such as silicon dioxide or alumina powder and dried, and the drie...

S. Iwao

1974-01-01

185

Baking powder pica mimicking preeclampsia.  

PubMed

We report a case of baking powder pica during pregnancy that was associated with maternal hypertension, hypokalemia, and elevated liver function tests. After discontinuation of baking powder ingestion and correction of electrolyte abnormalities, the blood pressure and the liver function tests normalized. PMID:1442966

Barton, J R; Riely, C A; Sibai, B M

1992-07-01

186

Organic vs. traditional potato powder  

Microsoft Academic Search

In this work the profile of primary metabolites in potato (Solanum tuberosum L., cultivar Agria) grown under organic vs traditional farming system was studied, and the influence of heat processing (for producing potato powder) on nutritionally important compounds such as essential amino acids, proteins and carbohydrates was evaluated. The potato powder was obtained by means of a drum dryer using

Petronia Carillo; Domenico Cacace; Stefania De Pascale; Mariateresa Rapacciuolo; Amodio Fuggi

187

Research and development of metal powder for magnetic recording  

NASA Astrophysics Data System (ADS)

Since its first application within the compact cassette in 1978, magnetic recording media using metal powder have been improved at a rate of roughly 1 dB per year as a result of advances in such fields as tape materials, tape-making technologies, etc. Today, metal tapes have a widely expanded application area, including video and data-information applications. Dowa Mining Co., Ltd., began its research regarding magnetic powder for recording media in 1978. The Company successfully developed metal powder for 8 mm video tape. Since then, Dowa has endeavored to improve the magnetic properties and reduce the particle size of metal powder. It accomplishes these goals through the full use of the Company's unique Al doping method. Especially, during the past several years, significant improvements of the magnetic properties of metal powder have been achieved. These improvements have resulted from the introduction of new technologies, including Fe-Co alloying, sintering prevention, new reaction processes, and many other new techniques. Currently, Dowa Mining is supplying a new type of metal powder for the most technologically advanced high-density recording media. Dowa's new metal powder has an axis length of 0.1 ?m, Hc of 2400 Oe, and ?s of 155 emu/g.

Hisano, Seiichi; Saito, Kazuhisa

1998-12-01

188

3D CO2 laser synthesis from thermoreactive resin powder  

NASA Astrophysics Data System (ADS)

Short review of 3-D Laser Synthesis (3D LS) or Rapid Prototyping (RP) is given, including three mali directions such as stereolithography (STL), laminated object manufacturing (LOM) and selective laser sintering (SLS). Comparative advantages and disadvantages of every one of them are discussed. The new direction of 3-D LS is suggested, combining advantages of STL and SLS. This direction based on the creation of 3D models from the resin's powder. The physical processes of the new technique similar with STL- process. In spite of the phase state of the initial material (powder) the mechanism of solidification has many skills of STL with viscous digomer. There are many new possibilities in the process with powder polymerization. One can use not mechanical devices (which are very complex) for powder deposition but electrostatic and so on. Some physical phenomena of powder solidification under the CO2-laser action are studied, as speed of the process, which is much higher than under the conventional heating and so on. The experimental results of the process investigation are discussed. In particular the chemical analysis of the solidificated model is made which confirm that initial powder under laser treatment gave perfect resin. Main advantages of the new methods are the cheapness of the initial material and good mechanical quality of models, which expands the field of application of models made with described powder.

Veiko, Vadim P.; Yakovlev, A. G.

1998-12-01

189

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

Code of Federal Regulations, 2010 CFR

...2009-04-01 2009-04-01 false Buffered penicillin powder, penicillin powder with buffered aqueous diluent. 520...FORM NEW ANIMAL DRUGS § 520.1696a Buffered penicillin powder, penicillin powder with buffered...

2009-04-01

190

AVLIS modified direct denitration: UO{sub 3} powder evaluation  

SciTech Connect

The evaluation study demonstrated that AVLIS-enriched uranium converted to UO{sub 3} can be used to prepare UO{sub 3} pellets having densities in the range required for commercial power reactor fuel. Specifically, the program has demonstrated that MDD (Modified Direct Denitration)-derived UO{sub 2} powders can be reduced to sinterable UO{sub 2} powder using reduction techniques that allow control of the final powder characteristics; the resulting UO{sub 2} powders can be processed/sintered using standard powder preparation and pellet fabrication techniques to yield pellets with densities greater than 96% TD; pellet microstructures appear similar to those of power reactor fuel, and because of the high final pellet densities, it is expected that they would remain stable during in-reactor operation; the results of the present study confirm the results of a similar study carried out in 1982 (Davis and Griffin 1992). The laboratory processes were selected on the basis that they could be scaled up to standard commercial fuel processing. However, larger scale testing may be required to establish techniques compatible with commercial fuel fabrication techniques.

Slagle, O.D.; Davis, N.C.; Parchen, L.J.

1994-02-01

191

Effect of surface coating with magnesium stearate via mechanical dry powder coating approach on the aerosol performance of micronized drug powders from dry powder inhalers.  

PubMed

The objective of this study was to investigate the effect of particle surface coating with magnesium stearate on the aerosolization of dry powder inhaler formulations. Micronized salbutamol sulphate as a model drug was dry coated with magnesium stearate using a mechanofusion technique. The coating quality was characterized by X-ray photoelectron spectroscopy. Powder bulk and flow properties were assessed by bulk densities and shear cell measurements. The aerosol performance was studied by laser diffraction and supported by a twin-stage impinger. High degrees of coating coverage were achieved after mechanofusion, as measured by X-ray photoelectron spectroscopy. Concomitant significant increases occurred in powder bulk densities and in aerosol performance after coating. The apparent optimum performance corresponded with using 2% w/w magnesium stearate. In contrast, traditional blending resulted in no significant changes in either bulk or aerosolization behaviour compared to the untreated sample. It is believed that conventional low-shear blending provides insufficient energy levels to expose host micronized particle surfaces from agglomerates and to distribute guest coating material effectively for coating. A simple ultra-high-shear mechanical dry powder coating step was shown as highly effective in producing ultra-thin coatings on micronized powders and to substantially improve the powder aerosolization efficiency. PMID:23196863

Zhou, Qi Tony; Qu, Li; Gengenbach, Thomas; Larson, Ian; Stewart, Peter J; Morton, David A V

2012-11-30

192

Understanding the influence of powder flowability, fluidization and de-agglomeration characteristics on the aerosolization of pharmaceutical model powders.  

PubMed

The aim of this study was to investigate the influence of the intrinsic inter-particulate cohesion of model pharmaceutical powders on their aerosolization from a dry powder inhaler. Two cohesive poly-disperse lactose powders with median particle sizes of around 4 and 20 microm were examined. The results showed that after dry coating with magnesium stearate, their flowability, fluidization and de-agglomeration behaviours could be substantially improved, as indicated by powder rheometry, shear testing and laser diffraction aerosol testing. This was achieved by reducing their cohesiveness via surface modification. In contrast to some previous reports, this study demonstrated how powder aerosolization may be improved more significantly and consistently (for widely varying air flow rates) by substantially reducing their inter-particulate cohesive forces. This study contributes to the understanding of the relationship between intrinsic cohesive nature and bulk properties such as flowability, fluidization and de-agglomeration and its impact on their aerosolization, which is fundamental and critical in the optimal design of dry powder inhaler formulations. The intensive mechanical dry coating technique also demonstrated a promising potential to improve aerosolization efficiency of fine cohesive model powders. PMID:20433919

Zhou, Qi Tony; Armstrong, Brian; Larson, Ian; Stewart, Peter J; Morton, David A V

2010-04-28

193

Thermal analysis of pentaerythritol tetranitrate and development of a powder aging model  

SciTech Connect

We have applied a range of different physical and thermal analysis techniques to characterize the thermal evolution of the specific surface area of pentaerythritol tetranitrate (PETN) powders. Using atomic force microscopy we have determined that the mass transfer mechanism leading to powder coarsening is probably sublimation and redeposition of PETN. Using thermogravimetric analysis we have measured vapor pressures of PETN powders whose aging will be simulated in future work. For one specific powder we have constructed an empirical model of the coarsening that is fit to specific surface area measurements at 60 C to 70 C to provide predictive capability of that powder's aging. Modulated differential scanning calorimetry and mass spectroscopy measurements highlight some of the thermal behavior of the powders and suggest that homologue-based eutectics and impurities are localized in the powder particles.

Brown, Geoffrey W [Los Alamos National Laboratory; Sandstrom, Mary M [Los Alamos National Laboratory; Giambra, Anna M [Los Alamos National Laboratory; Archuleta, Jose G [Los Alamos National Laboratory; Monroe, Deirde C [Los Alamos National Laboratory

2009-01-01

194

30 CFR 56.6133 - Powder chests.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 2010-07-01 false Powder chests. 56.6133 Section 56...ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE SAFETY AND HEALTH...Explosives Storage § 56.6133 Powder chests. (a) Powder chests...

2010-07-01

195

30 CFR 56.6133 - Powder chests.  

Code of Federal Regulations, 2010 CFR

...2009-07-01 2009-07-01 false Powder chests. 56.6133 Section 56...ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE SAFETY AND HEALTH...Explosives Storage § 56.6133 Powder chests. (a) Powder chests...

2009-07-01

196

Properties of Prealloyed Steel Powder Metallurgy Products.  

National Technical Information Service (NTIS)

The applicability of conventional powder metallurgy fabrication procedures to prealloyed steel powders was investigated. Fifteen lots of steel powder, representing six different major alloy types (4130, 1040, 8620, 4650, 8650, and 9450), have been formed ...

K. R. Sump R. E. Westerman

1971-01-01

197

21 CFR 73.1646 - Bronze powder.  

Code of Federal Regulations, 2010 CFR

...color additive bronze powder is a very fine metallic powder prepared from alloys...virgin electrolytic copper and zinc with small...zinc, tin, and copper content shall be based...weight of the dried powder after being...

2010-04-01

198

21 CFR 73.2647 - Copper powder.  

Code of Federal Regulations, 2010 CFR

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

2010-04-01

199

21 CFR 73.2647 - Copper powder.  

Code of Federal Regulations, 2010 CFR

...2009-04-01 2009-04-01 false Copper powder. 73.2647 Section 73.2647...CERTIFICATION Cosmetics § 73.2647 Copper powder. (a) Identity and specifications. The color additive copper powder shall conform in identity...

2009-04-01

200

21 CFR 73.1646 - Bronze powder.  

Code of Federal Regulations, 2010 CFR

...color additive bronze powder is a very fine metallic powder prepared from alloys...virgin electrolytic copper and zinc with small...zinc, tin, and copper content shall be based...weight of the dried powder after being...

2009-04-01

201

Compaction of Amorphous Ferromagnetic Metal Powders.  

National Technical Information Service (NTIS)

The attractive magnetic properties of certain amorphous metal powders might be exploited in the electrical industry if the powders can be consolidated into relatively dense compacts. The production of integral bodies of an amorphous powder was attempted u...

R. D. Caligiuri

1982-01-01

202

21 CFR 73.1645 - Aluminum powder.  

Code of Federal Regulations, 2012 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

203

21 CFR 73.2645 - Aluminum powder.  

Code of Federal Regulations, 2012 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

204

21 CFR 73.2647 - Copper powder.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 2013-04-01 false Copper powder. 73.2647 Section 73...CERTIFICATION Cosmetics § 73.2647 Copper powder. (a) Identity and specifications. The color additive copper powder shall conform in identity...

2013-04-01

205

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

206

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

207

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

208

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

209

Shock compaction of molybdenum powder  

SciTech Connect

Shock recovery experiments carried out in the 9 to 12 GPa range on 1.4 distension Mo appear adequate to compact to full density (< 45 ..mu..m) powders. However, the stress levels 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 ..mu..m particles. The present model predicts that for powders 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 ..mu..m range.

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

1983-09-01

210

Microstructures of explosively consolidated rapidly solidified aluminium and Al-Li alloy powders  

Microsoft Academic Search

The microstructures and the characteristics of water-atomized, nitrogen gas-atomized Al powders and ultrasonic argon gas-atomized Al-Li alloy powder were investigated by means of metallography, SEM, Auger electron spectroscopy and X-ray diffraction techniques. Rapidly solidified powders were explosively consolidated into different sized cylinders under various explosive parameters. The explosively consolidated compacts have been tested and analysed for density microhardness, retention of

Jim-Yuan Zhang; Baoren Ai; Chunlan Liu; Ruizhen Zhu; Dengxia Zhang; Chenghui Ma

1992-01-01

211

Fabrication of ex situ processed MgB 2 wires using nano carbon doped powder  

Microsoft Academic Search

We fabricated ex situ MgB2 wires using C-doped MgB2 powder as a precursor in order to improve the core density of the wires and their C doping content. The C-doped powder was prepared with Mg, B, and nano carbon (NC) powders by the in situ technique and then MgB2?xCx (x=0, 0.01, and 0.03) wires were fabricated by the ex situ

C. M. Lee; J. H. Park; S. M. Hwang; J. H. Lim; J. Joo; W.-N. Kang; C.-J. Kim

2009-01-01

212

Fabrication of ex situ processed MgB2 wires using nano carbon doped powder  

Microsoft Academic Search

We fabricated ex situ MgB2 wires using C-doped MgB2 powder as a precursor in order to improve the core density of the wires and their C doping content. The C-doped powder was prepared with Mg, B, and nano carbon (NC) powders by the in situ technique and then MgB2-xCx (x = 0, 0.01, and 0.03) wires were fabricated by the

C. M. Lee; J. H. Park; S. M. Hwang; J. H. Lim; J. Joo; W.-N. Kang; C.-J. Kim

2009-01-01

213

Mechanical properties of rapidly solidified aluminium alloys extruded from amorphous or nanocrystalline powders  

Microsoft Academic Search

Amorphous powders of the Al-Ni-Mm system and nanocrystalline powders of the Al-Ni-Mm-Zr system (Mm ? misch metal) were produced by a high-pressure gas atomization technique. Following degassing, the powders were extruded with a reduction ratio of 10:1. Tensile tests were performed for as-extruded alloys. High values of tensile strength and elastic modulus were obtained in both alloy systems. The maximum

H. Nagahama; K. Ohtera; K. Higashi; A. Indue; T. Masumoto

1993-01-01

214

Thermal behavior of aluminum powder and potassium perchlorate mixtures by DTA and TG  

Microsoft Academic Search

In this work the thermal decomposition characteristics of micron sized aluminum powder+potassium perchlorate pyrotechnic systems were studied with thermal analytical techniques. The results show that the reactivity of aluminum powder in air increases as the particle size decreases. Pure aluminum with 5?m particle size has a fusion temperature about 647C, but this temperature for 18?m powder is 660C. Pure potassium

S. M. Pourmortazavi; M. Fathollahi; S. S. Hajimirsadeghi; S. G. Hosseini

2006-01-01

215

Crystallization of comminuted boron powders  

Microsoft Academic Search

An x-ray diffraction investigation has established that, irrespective of their degree of amorphization, comminuted boron powders crystallize after melting in the rhombohedral structure, i.e., revert to their original crystalline state.

K. P. Tsomaya; D. L. Gabuniya; . A. Knyshev; V. A. Kobyakov

1975-01-01

216

Analysis of the headspace composition of smokeless powders using GC-MS, GC-?ECD and ion mobility spectrometry.  

PubMed

Smokeless powder additives are usually detected from an extraction of post-blast residues or unburned powder particles followed by chromatographic analyses. This work presents the first comprehensive study of the detection of volatile and semi-volatile additives of smokeless powders using solid phase microextraction (SPME) as a sampling and pre-concentration technique. The goal of this study is to generate a list of compounds that can be used as target compounds for the vapor phase detection of smokeless powders. Sixty-five smokeless powders were studied using laboratory-based gas chromatography techniques and a field deployable ion mobility spectrometer (IMS). The detection of diphenylamine, ethyl and methyl centralite, 2,4-dinitrotoluene, diethyl and dibutyl phthalate by IMS is suggested as a method to indicate the presence of smokeless powders. A previously reported SPME-IMS analytical approach facilitates rapid sub-nanogram detection of the vapor phase components of smokeless powders. The analyte mass present in the vapor phase was sufficient for a SPME fiber to extract and concentrate most analytes at amounts above the detection limits of both the GC and the IMS methods. Analysis of 65 different smokeless powder samples revealed that diphenylamine was present in the headspace of 96% of the powders studied. Ethyl centralite was detected in 47% of the powders and 8% of the powders contained methyl centralite. Nitroglycerin was the dominant peak present in the headspace of the double-based powders. Another important headspace component, 2,4-dinitrotoluene, was detected in 44% of the powders comprising both double and single-based powders. Static headspace SPME of small amounts (?100 mg) of smokeless powder samples for ?5 min at room temperature resulted in the successful detection of the headspace components, demonstrating the applicability of the technique for field detection of smokeless powders using IMS as a detector. PMID:21109373

Joshi, Monica; Rigsby, Kia; Almirall, Jose R

2010-11-24

217

Preparation of zirconium boride powder  

Microsoft Academic Search

An intermediate reaction in the synthesis of ZrB powder by the reduction of ZrO with BC and carbon was confirmed through both thermodynamical calculation and experimental results. Because the intermediate product BO was volatile, excess boron should be added to compensate for the boron loss in order to prepare high-purity ZrB powder. The synthesis temperatures of the intermediate reaction and

Hong Zhao; Yu He; Zongzhe Jin

1995-01-01

218

Entrainment of lactose inhalation powders: a study using laser diffraction.  

PubMed

We have investigated the mechanism of entrainment of lactose inhalation blends released from a dry powder inhaler using a diffraction particle size analyser (Malvern Spraytec). Whether a powder blend entrains as a constant stream of powder (the "erosion" mechanism) or as a few coarse plugs (the "fracture" mechanism) was found by comparing transmission data with particle size information. This technique was then applied to a lactose grade with 0, 5 and 10wt% added fine particles. As the wt% fines increased, the entrainment mechanism was found to change from a mild fracture, consisting of multiple small plugs, to more severe fracture with fewer plugs. The most severe fracture mechanism consisted of either the powder reservoir emptying as a single plug, or of the reservoir emptying after a delay of the order of 0.1s due to the powder sticking to its surroundings. Further to this, three different inhalation grades were compared, and the severity of the fracture was found to be inversely proportional to the flowability of the powder (measured using an annular ring shear tester). By considering the volume of aerosolised fine particles in different blends it was determined that the greater the volume of fines added to a powder, the smaller the fraction of fines that were aerosolised. This was attributed to different behaviour when fines disperse from carrier particles compared with when they disperse from agglomerates of fines. In summary, this paper demonstrates how laser diffraction can provide a more detailed analysis of an inhalation powder than just its size distribution. PMID:20417708

Watling, C P; Elliott, J A; Cameron, R E

2010-04-24

219

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.

Katz, Joseph L. (Baltimore, MD); Hung, Cheng-Hung (Baltimore, MD)

1993-01-01

220

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

221

Investigation of the recyclability of powder coatings  

Microsoft Academic Search

100% recyclability is one of the major advantages of powder coating. However, it can never be achieved in reality. Coating powders, especially finer powders with particle size below 30?m, were found to have much worse flow performances after recycling from electrostatic spraying so as to decrease the recyclability. Therefore, this study was designed to investigate recycled coating powders to determine

Jing Fu; Matthew Krantz; Hui Zhang; Jesse Zhu; Harry Kuo; Yar Ming Wang; Karen Lis

2011-01-01

222

30 CFR 57.6901 - Black powder.  

Code of Federal Regulations, 2010 CFR

...6901 Black powder. (a) Black powder shall be used for...stone. (b) Containers of black powder shall be (1) Nonsparking...of this section. (c) Black powder shall be transferred...damaged explosives. (f) Holes shall not be reloaded for...

2009-07-01

223

30 CFR 56.6901 - Black powder.  

Code of Federal Regulations, 2010 CFR

...6901 Black powder. (a) Black powder shall be used for...stone. (b) Containers of black powder shall be (1) Nonsparking...of this section. (c) Black powder shall be transferred...damaged explosives. (f) Holes shall not be reloaded for...

2010-07-01

224

30 CFR 56.6901 - Black powder.  

Code of Federal Regulations, 2010 CFR

...6901 Black powder. (a) Black powder shall be used for...stone. (b) Containers of black powder shall be (1) Nonsparking...of this section. (c) Black powder shall be transferred...damaged explosives. (f) Holes shall not be reloaded for...

2009-07-01

225

30 CFR 57.6901 - Black powder.  

Code of Federal Regulations, 2010 CFR

...6901 Black powder. (a) Black powder shall be used for...stone. (b) Containers of black powder shall be (1) Nonsparking...of this section. (c) Black powder shall be transferred...damaged explosives. (f) Holes shall not be reloaded for...

2010-07-01

226

Reduction of sidewall inclination and blast lag of powder blasted channels  

Microsoft Academic Search

Powder blasting (abrasive jet machining) is a fast directional machining technique for brittle materials like silicon and glass. The cross-section of a powder blasted channel has a rounded V-shape. These inclined sidewalls are caused by the typical impact angle dependent removal rate for brittle materials. It has a negative influence on the channel depth and aspect ratio, and results in

Henk Wensink; Miko C. Elwenspoek

2002-01-01

227

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

228

Spray-dried ceramic powders: A quantitative correlation between slurry characteristics and shapes of the granules  

Microsoft Academic Search

The characteristics and consequently the properties of ceramic coatings performed using plasma spraying means depend not only on the operating conditions but also on the powder feedstock. Oxide powders are commonly prepared in one stage or in a combination of stages of fusing, crushing, agglomerating and sintering. The spray drying process (which corresponds to the agglomerating route) is a technique

G. Bertrand; P. Roy; C. Filiatre; C. Coddet

2005-01-01

229

Static pressure distribution in a powder-binder 2-phase medium  

Microsoft Academic Search

Because of its high potential for near-net shape manufacturing, metal powder injection molding (MIM) has attracted a growing attention recently. The MIM technique generally consists of the following four processes: metal powder-liquid binder mixing, injection of mixed medium into molds, debinding and sintering. Each MIM process has its peculiar problems to be overcome. This study is one of the approaches

H. Yoshida; S. Miyazawa

1995-01-01

230

A constitutive model and FE simulation for the sintering process of powder compacts  

Microsoft Academic Search

A model for describing the entire sintering process of powder compacts is presented based on the thermal elasto-viscoplastic theory. The predications of shrinkage and stress changes of WC-6%Co powder compacts during sintering process are simulated using the ABAQUS code. It was found that simulation results for displacements are a good fit of the experimental data. In situ measurement technique and

Michael Gasik; Baosheng Zhang

2000-01-01

231

Plasma-Chemical Synthesis of Nanosized Powders-Nitrides, Carbides, Oxides, Carbon Nanotubes and Fullerenes  

NASA Astrophysics Data System (ADS)

In this article the plasma-chemical synthesis of nanosized powders (nitrides, carbides, oxides, carbon nanotubes and fullerenes) is reviewed. Nanosized powders - nitrides, carbides, oxides, carbon nanotubes and fullerenes have been successfully produced using different techniques, technological apparatuses and conditions for their plasma-chemical synthesis.

Katerina, Zaharieva; Gheorghi, Vissokov; Janis, Grabis; Slavcho, Rakovsky

2012-11-01

232

Deposition of metal on powders by a spraying process employing electron-beam heating  

Microsoft Academic Search

Metal deposition on abrasive powders such as those of diamond or Borazon (cubic boron nitride) is widely used today as a method of improving the strength characteristics of these powders and ensuring that their particles are held securely in abrasive tools with organic, ceramic, and metallic binders. The operation is usually performed by the techniques of application of metals to

Yu. V. Naidich; G. A. Kolesnichenko; B. D. Kostyuk

1973-01-01

233

Thermal analysis of pentaerythritol tetranitrate and development of a powder aging model  

Microsoft Academic Search

We have applied a range of different physical and thermal analysis techniques to characterize the thermal evolution of the specific surface area of pentaerythritol tetranitrate (PETN) powders. Using atomic force microscopy we have determined that the mass transfer mechanism leading to powder coarsening is probably sublimation and redeposition of PETN. Using thermogravimetric analysis we have measured vapor pressures of PETN

Geoffrey W Brown; Mary M Sandstrom; Anna M Giambra; Jose G Archuleta; Deirde C Monroe

2009-01-01

234

Contact thermal conductivity of a powder bed in selective laser sintering  

Microsoft Academic Search

Estimation of the temperature field in the powder bed in selective laser sintering process is a key issue for understanding the sintering\\/binding mechanisms and for optimising the technique. Heat transfer may be strongly affected by formation and growth of necks between particles due to sintering when the contact conductivity becomes predominant in the powder bed effective thermal conductivity. The necks

A. V. Gusarov; T. Laoui; L. Froyen; V. I. Titov

2003-01-01

235

Factors Influencing the Properties of Rifampicin Liposome and Applications for Dry Powder Inhaler  

Microsoft Academic Search

RIF encapsulated liposome vesicles were prepared by chloroform film method followed by freeze drying technique to obtain a dry powder for aerosol delivery. The freeze drying conditions were designed according to the DSC results of the liposome suspension. Three sugars (mannitol, lactose and trehalose) were used as a cryoprotectant of liposome dry powder. NR 8383 cell line was used to

N. Changsan; T. Srichana

2007-01-01

236

Powder Metallurgy Processing of Dual Phase Al Rich Fe-Al Intermetallics.  

National Technical Information Service (NTIS)

A powder metallurgy technique was used to fabricate two different dual-phase Al-rich Fe-Al intermetallics, namely, FeAl2-Fe2Al5 and FeAl3-Fe2Al5. Powders were first produced by inert gas atomization, and then subsequently consolidated by hot pressing at 1...

Y. L. Jeng R. Hayes J. Wolfenstine E. J. Lavernia

1995-01-01

237

Microstructural evolution of mullite during the sintering of kaolin powder compacts  

Microsoft Academic Search

Kaolin particles are usually flaky in shape. In the present study, kaolin powder compacts were prepared by applying the die-pressing technique. The kaolin flakes tend to lie down on the plane which is perpendicular to the die-pressing direction. The powder compact thus shows anisotropic shrinkage after firing. A series of phase transformations take place as the kaolin is fired at

C. Y. Chen; G. S. Lan; W. H. Tuan

2000-01-01

238

Silicon Chemical Vapor Deposition (CVD) on microporous powders in a fluidized bed  

Microsoft Academic Search

The fluidized bed Chemical Vapor Deposition (CVD) process constitutes today one of the most efficient techniques to modify the surface properties of dense (nonporous) powders. The success encountered in this field is the reason why this process has been extended to the treatment of microporous powders, for which there are very important industrial interests. The article presents an experimental analysis

S Kouadri-Mostefa; P Serp; M Hmati; B Caussat

2001-01-01

239

Evaluation of Black Powder Produced by Indiana Army Ammunition Plant.  

National Technical Information Service (NTIS)

Closed-bomb techniques were used to determine quickness and burning-rate equations for two standard class-one black powders made by DuPont and GOEX; these results were compared to similar measurements on material produced by the Indiana Army Ammunition Pl...

R. A. Sasse H. E. Holmes W. P. Aungst J. O. Doali R. E. Bowman

1984-01-01

240

Synthesis of Nanostructured LaB6 Powders.  

National Technical Information Service (NTIS)

Nanocrystalline powders of LaB6 with an average crystallite size of 20 nm, as determined from x-ray diffraction analysis, have been obtained using a combustion synthesis technique that makes use of lanthanum nitrate, boron, and carbohydrazide as precursor...

O. A. Graeve

2007-01-01

241

Powder metallurgy of vanadium and its alloys (review)  

SciTech Connect

This article reviews the current powder metallurgy technology of vanadium and its alloys. Data are given on sintering, compacting, electrowinning and other current production techniques, as well as on the corrosion behavior and mechanical and physical properties of alloys produced by these different methods. The use of vanadium alloys as reactor and jet engine materials is also briefly discussed.

Radomysel'skii, I.D.; Solntsev, V.P.; Evtushenko, O.V.

1987-10-01

242

Shock consolidation of rapidly solidified type 304 stainless steel powders  

Microsoft Academic Search

Shock compaction of dissolved gas (DGA) and centrifugal atomized (CA) Type 304 SS powders have been assessed using explosive techniques. The goal of the study is to produce full dense crack free monoliths for structure\\/property correlations, retaining the unique microstructural features afforded by RSP. Peak shock pressures range from 5 to 30 GPa, and fully dense compacts have been produced

J. E. Flinn; G. E. Korth; R. A. Graham; R. C. Green; L. H. Schoenlein

2008-01-01

243

Dynamic consolidation of rapidly solidified titanium alloy powders by explosives  

Microsoft Academic Search

Consolidation of rapidly solidified titanium alloy powders employing explosively generated shock pressures was carried out successfully. The cylindrical explosive consolidation technique was utilized, and compacts with densities in the range 97 to 100% were produced. Better consolidation (with more interparticle melting regions and less cracking) was achieved by using a double tube design in which the outer tube (flyer tube)

H. L. Coker; M. A. Meyers; J. F. Wessels

1991-01-01

244

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

245

Synchrotron powder diffraction on Aztec blue pigments  

NASA Astrophysics Data System (ADS)

Some samples of raw blue pigments coming from an archaeological rescue mission in downtown Mexico City have been characterized using different techniques. The samples, some recovered as a part of a ritual offering, could be assigned to the late Aztec period (XVth century). The striking characteristic of these samples is that they seem to be raw pigments prior to any use in artworks, and it was possible to collect a few ?g of pigment after manual grain selection under a microscopy monitoring. All pigments are made of indigo, an organic colorant locally known as ail or xiuhquilitl. The colorant is always found in combination with an inorganic matrix, studied by powder diffraction. In one case the mineral base is palygorskite, a rare clay mineral featuring micro-channels in its structure, well known as the main ingredient of the Maya blue pigment. However, other samples present the minerals sepiolite (a clay mineral of the palygorskite family) and calcite. Another sample contains barite, a mineral never reported in prehispanic paints. We present the results of characterization using high resolution powder diffraction recorded at the European Synchrotron Radiation Facility (BM25A, SpLine beamline) complemented with other techniques. All of them gave consistent results on the composition. A chemical test on resistance to acids was done, showing a high resistance for the palygorskite and eventually sepiolite compounds, in good agreement with the excellent resistance of the Maya blue.

Snchez Del Ro, M.; Gutirrez-Len, A.; Castro, G. R.; Rubio-Zuazo, J.; Sols, C.; Snchez-Hernndez, R.; Robles-Camacho, J.; Rojas-Gaytn, J.

2008-01-01

246

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

SciTech Connect

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

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

2007-01-01

247

Developments in Die Pressing Strategies for Low-Cost Titanium Powders  

SciTech Connect

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

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

2009-05-01

248

Spectroscopic investigations of nanohydroxyapatite powders synthesized by conventional and ultrasonic coupled sol-gel routes.  

PubMed

In the present work, the synthesis and characterization of nano-HAP powders by a novel ultrasonic coupled sol-gel synthesis is reported. The obtained powders were sintered by conventional means at different temperatures. In addition to this, HAP powders prepared through the sol-gel method without the aid of the ultrasonic waves is also studied. The obtained nano-HAP powders were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and scanning electron microscopic (SEM) techniques. The results have proved that the nano-HAP powders synthesized by ultrasonic coupled sol-gel synthesis showed remarkable reduction in the particle size when compared with the conventional sol-gel method and hence these powders could be used as a coating material in biomedical applications. PMID:18356096

Gopi, D; Govindaraju, K M; Victor, Collins Arun Prakash; Kavitha, L; Rajendiran, N

2008-02-14

249

A fluidized bed process for electron sterilization of powders  

Microsoft Academic Search

A small capacity (100 g.s?1) pilot system is described for presentation of powders and fine aggregates at high velocity, to an electron beam. Electron beam dose rate is continuously monitored in real time, while the thickness of the fluidized bed used to pneumatically transport the product can be monitored and controlled using beta-gauge techniques. Using electron paramagnetic resonance (EPR) techniques,

Marc F. Desrosiers; Vitaly Yu. Nagy

1998-01-01

250

A fluidized bed process for electron sterilization of powders  

Microsoft Academic Search

A small capacity (100 g.s-1) pilot system is described for presentation of powders and fine aggregates at high velocity, to an electron beam. Electron beam dose rate is continuously monitored in real time, while the thickness of the fluidized bed used to pneumatically transport the product can be monitored and controlled using beta-gauge techniques. Using electron paramagnetic resonance (EPR) techniques,

Sam V. Nablo; James C. Wood; Marc F. Desrosiers; Vitaly Yu. Nagy

1998-01-01

251

Oxide-dispersion strengthening of porous powder metalurgy parts  

DOEpatents

Oxide dispersion strengthening of porous metal articles includes the incorporation of dispersoids of metallic oxides in elemental metal powder particles. Porous metal articles, such as filters, are fabricated using conventional techniques (extrusion, casting, isostatic pressing, etc.) of forming followed by sintering and heat treatments that induce recrystallization and grain growth within powder grains and across the sintered grain contact points. The result is so-called "oxide dispersion strengthening" which imparts, especially, large increases in creep (deformation under constant load) strength to the metal articles.

Judkins, Roddie R. (Knoxville, TN)

2002-01-01

252

Real-Time Ultrasonic Nondestructive Evaluation of Green State Ceramic Powders during Compaction  

Microsoft Academic Search

A real-time ultrasonic technique for the nondestructive evaluation of ceramic powders during compaction has been demonstrated. Initial results indicate that this technique can detect the presence of hard agglomerates in a spray-dried alumina powder. The proposed sensor could be employed by industry to spot flawed parts prior to removing them from the die, and to provide on-line criteria for control

Martin P. Jones; Gerald V. Blessing

1986-01-01

253

Electromagnetic and microwave absorption properties of Alnico powder composites  

NASA Astrophysics Data System (ADS)

A novel application of Alnico powder as a thinner microwave absorbing material was investigated. The flake-like Alnico fine powder was found to have excellent complex permeability ?=?-j? and permittivity ?=?-j? in the frequency range of 2 18 GHz. The powder was made from extremely brittle ribbons which were produced using a single roller melt spinning technique. The dependences of the absorption characteristics on the frequency, thickness, and both the dielectric permittivity and magnetic permeability were obtained based on a model in which an electromagnetic wave is incident normal to the surface of the absorbing material backed by a perfect conductor. The samples have the largest values of ? and ? at 2 GHz. A minimum reflection loss of -11.4 dB is obtained at 2 GHz for composite with volume fraction 60% of Alnico powder and absorber thickness of 1.8 mm. The results show that flake-like Alnico powder composites can be applied as thinner microwave absorbers in S-band (2 4 GHz).

Zhang, Baoshan; Lu, Gang; Feng, Yong; Xiong, Jie; Lu, Huaixian

2006-04-01

254

Metallography of powder metallurgy materials  

Microsoft Academic Search

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

Alan Lawley; Thomas F. Murphy

2003-01-01

255

Pinwheel patterns and powder diffraction  

Microsoft Academic Search

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

Michael Baake; D. Frettlh; Uwe Grimm

2007-01-01

256

Flow Properties of Powder III  

Microsoft Academic Search

When glass granules coated with various amounts of oleic acid are packed into the annular space between two rotating coaxial cylinders, they exhibit the so-called plug flow around the inner cylinder. Theoretically, we have established a method of measuring the internal friction coefficient and cohesive force of loosely packed powder by means of a rotating coaxial cylinder rheometer. The internal

Shin'ichi Taneya

1969-01-01

257

Powdered epoxy resin test methods  

Microsoft Academic Search

The author describes several test methods which may be used to evaluate powdered epoxy resins for their potential use as integral insulation on fractional horsepower motor iron. These are the edge coverage test method, the hot plate gel time test method, the glass pellet flow test method, and the steel panel impact test method. These test methods may be of

N. Hanssen

1991-01-01

258

Shock Compaction of Molybdenum Powder.  

National Technical Information Service (NTIS)

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 a...

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

1983-01-01

259

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...

260

Solar drying of custard powder  

Microsoft Academic Search

A large scale forced convection solar drying system has been designed and fabricated, comprising an array of forty solar collectors and three drying cabinets with a blower. Such a system yields 300 kg of dry product of custard powder in a normal sunshine day. It is shown that such a system is feasible and has an ability to save large

R. S. Pawar; M. G. Takwale; V. G. Bhide

1995-01-01

261

Powder metallurgy of titanium alloys  

Microsoft Academic Search

The powder metallurgy of titanium alloys is studied with attention given to blended elemental and prealloyed (PA) approaches. The PA method leads to mechanical behavior in all respects at least at ingot metallurgy levels. The use of the PA method in the aerospace industry is discussed. 230 refs.

F. H. Froes; D. Eylon

1990-01-01

262

Microstructure and properties of WC-10%Co-4% Cr Spray powders and coatings: Part 1. Powder characterization  

NASA Astrophysics Data System (ADS)

WC-10% Co-4% Cr1 represents an important composition for thermally sprayed hardmetal-like coatings that are applied when simultaneous wear and corrosion resistance is required. In this paper, four commercially available spray powders obtained by various production techniques (sintering and crushing, agglomeration and plasma densification) were thoroughly characterized using a broad variety of physical and chemical methods, including scanning electron microscopy (SEM), energy-dispersive x-ray (EDX), x-ray diffraction, adsorption, mercury intrusion, and helium pycnometry. Special emphasis is given to the interdependence of the chemical and phase compositions. The cooling rate applied during preparation of the spray powders seems to be responsible for the appearance of equilibrium or nonequilibrium phases, as was established from the investigation of the spray powders after heat treatment at 1000 C. The amount of Cr added to the composition, 4%, is higher than the solubility limit of chromium in the binder phase in the presence of WC; hence, a second carbide phase is formed. The carbon content determines which carbide phase is formed and how both cobalt and chromium are distributed between the hard and the binder phases. A substantial carbon deficiency leads to nearly complete bonding of both chromium and cobalt into carbide phases. As was shown by differential scanning calorimetry (DSC) experiments, such spray powders do not form a melt in the temperature range up to 1465 C, while powders containing clearly detectable amounts of metallic cobalt form a melt above 1210 C.

Berger, L.-M.; Ettmayer, P.; Vuoristo, P.; Mntyl, T.; Kunert, W.

2001-06-01

263

Powder Metallurgy Production of Structural Shapes.  

National Technical Information Service (NTIS)

The program involves an integrated and concurrent study of closely-related topics which represent major critical steps and/or problem areas in a wide variety of powder metallurgy processes. Areas of study include atomization, powder characteristics (and t...

A. Lawley H. L. Gaigher R. H. Haase R. W. Heckel M. J. Koczak

1971-01-01

264

Homogeneous Precipitation of Nickel Hydroxide Powders.  

National Technical Information Service (NTIS)

Precipitation and characterization of nickel hydroxide powders were investigated. A comprehensive precipitation model incorporating the metal ion hydrolysis, complexation and precipitation reactions was developed for the production of the powders with ure...

B. Mavis

2003-01-01

265

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

266

Characterization of Powder Coated Thermoplastic Composite.  

National Technical Information Service (NTIS)

Thermoplastic powder resin preforms are a relatively new form of composite preform material. Powder preforms offer improved handelability as well as the possibility to produce composites from resins that are difficult to prepreg. The purpose of this proje...

R. Cochran

1991-01-01

267

Powder Metallurgy Production of Structural Shapes.  

National Technical Information Service (NTIS)

This program has involved an integrated and concurrent study of closely-related topics representing major critical steps and/or problem areas in powder metallurgy processing. The areas of major concern have been: quench atomization; powder compaction; pow...

A. Lawley M. J. Koczak R. M. Koerner H. A. Kuhn H. C. Rogers

1973-01-01

268

Fe-nanoparticle coated anisotropic magnet powders for composite permanent magnets with enhanced properties  

NASA Astrophysics Data System (ADS)

Utilizing the chemical reduction of FeCl2 with NaBH4 in the presence of 2:17 Sm-Co powders, we synthesized composite Sm(Co0.699Fe0.213Cu0.064Zr0.024)7.4/nano-Fe anisotropic hard magnetic powders. The average particle size of the hard magnetic core powder was 21 ?m while the soft magnetic Fe nanoparticles deposited uniformly on the core powder had a particle size smaller than 100 nm. Different reaction protocols, such as immersion of the hard magnetic core powder in each reagent, the use of microemulsion (micelle) technique, or doubling the weight ratio of FeCl2 to core powder, led to different degrees of magnetic coupling of the hard and soft magnetic components of the composite powder. A reaction time of 180 s led to deposition of 3.5 wt % Fe nanoparticles and improved magnetic properties of the composite powder compared to the uncoated Sm(Co0.699Fe0.213Cu0.064Zr0.024)7.4 powder. The respective magnetic hysteresis parameters were 4?M18 kOe=11.3 kG, 4?Mr=11 kG, and iHc>20 kOe with a smooth demagnetization curve.

Marinescu, M.; Liu, J. F.; Bonder, M. J.; Hadjipanayis, G. C.

2008-04-01

269

Amorphous metal powder for coating substrates  

Microsoft Academic Search

The present invention is for a flat B containing amorphous powder based in Fe, Ni, Co or a combination thereof; a coating resulting from deposition of the powder; and a method for depositing the powder. The composition of the powder and the resulting coating consists essentially of the formulation: (Fe,Ni,Co) \\/sub bal\\/ Cr⁻(Mn,Mo,W)⁻ (B,Si,C)⁻(Al,Ti)⁻ where the subscripts are in atomic

J. Dickson; L. F. Nienart; D. W. Roth

1985-01-01

270

Regular Cu-based amorphous alloy powder  

Microsoft Academic Search

The plate-like powder of Cu60Zr30Ti10 amorphous alloy was prepared by ball milling. The amorphization and deformation mechanisms and thermodynamic properties were also investigated. The powders are milled into plate-like powders and their thicknesses decrease with increasing of milling time. After milling for 184h, the size of the powders decreases down to 250nm and an amorphous structure appears. The average deformation

An-hui Cai; Xiang Xiong; Yong Liu; Yong Zhou; Wei-ke An; Yun Luo

2010-01-01

271

METHOD FOR PRODUCTION OF SILVER POWDER  

Microsoft Academic Search

To diversify the range of products JSC Krastsvetmet developed a method for production of electro- lytic silver powders that are widely used in electronic industry for manufacturing contacts. The relevant specification (Silver Powder, TU43-1-702-87) (2) provides for production of two grades of silver powder, PSr1 and PSr2. The grade PSr1 powder shall contain particles with dimensions not larger than 56

E. Pavlov; V. Ilyashevich; S. Zhuravleva

2009-01-01

272

Review: aqueous tape casting of ceramic powders  

Microsoft Academic Search

Slurry formulations and processing parameters of the water-based tape casting of ceramic powders are reviewed. Additives include binders, like cellulose ethers, vinyl or acrylic-type polymers; plasticizers, like glycols; and dispersants, like ammonium salts of poly(acrylic acids). Mostly alumina powders have been employed. Hydrophobing of ceramic powders permits the aqueous processing even of water-reactive powders, like aluminium nitride. Non-toxicity and non-inflammability

D. Hotza; P. Greil

1995-01-01

273

Microstructural investigations of rapidly solidified Cu-Nb alloy powders produced by inert-gas atomization. Technical report  

SciTech Connect

This study presents a metallographic technique which enables the microstructural examination of the cross-sections of individual, fine-scale (10-75 um) powder particles. The technique was developed to permit characterization of the as-solidified features of Cu-based powders produced by high pressure inert gas atomization in order to relate the microstructures to processing history. In order to perform the necessary microscopy to elucidate the microstructural features, a metallographic technique was developed to permit characterization of the as-atomized microstructures within the individual powder particles. This technique involved classifying, mounting, and polishing through the diameters of individual powder particles and then using an attack etch to remove some of the copper matrix. This enabled characterization of the niobium-rich second phase. Secondary electron imaging on a scanning electron microscope provided the necessary resolution to characterize the second phase morphologies as a function powder-particle size, ultimately relating the microstructures to processing conditions.

Zeik, K.L.; Anderson, I.E.; Koss, D.A.; Howell, P.R.

1991-04-30

274

Process for manufacturing uranium dioxide powder  

Microsoft Academic Search

A process is described for manufacturing uranium dioxide powder which comprises forming fine uranium dioxide powder having a high sinterability and coarse uranium dioxide powder having a low sinterability continuously in one process by changing periodically the precipitation condition of the ammonium diuranate under the same condition of calcining and reducing of the ammonium diuranate. The thus obtained mixture of

Sh. I. Hasegawa; M. Sekine; E. Takano

1985-01-01

275

Reflection of Ultracold Neutrons from Powder Materials.  

National Technical Information Service (NTIS)

Diffusion of ultracold neutrons on powder copper, powder copper oxide and powder graphite has been observed and studied. It was the first experiment to show that it is possible on a level of approx. 10/sup -5/ to determine by measuring the reflection coef...

V. V. Golikov E. N. Kulagin Y. V. Nikitenko

1987-01-01

276

Sorption of nicotine to cellulose powders  

Microsoft Academic Search

The purpose of this study was to investigate the influence of the crystallinity, surface area, and pore volume of cellulose powders on the loading, release, and stability of nicotine. Four different types of cellulose powders with varying crystallinity index, surface area, and pore volume were produced and characterized. The powders were loaded with nicotine by rotary evaporation from an ethanol

Albert Mihranyan; Sven-Brje Andersson; Ragnar Ek

2004-01-01

277

Magnetic Orientation of BI-2212 Powder  

NASA Astrophysics Data System (ADS)

The Accelerator Lab at Texas A&M is developing a method of texturing Bi-2212 powder for an oriented powder multifilament round wire. Results of preliminary experiments relating to the orientation of Bi-2212 powders by magnetic fields are presented.

Damborsky, K.; McIntyre, P.; Pogue, N.

2010-04-01

278

Powder metallurgy repair of turbine components  

Microsoft Academic Search

An advanced powder metallurgy repair process called Liburdi Powder Metallurgy (LPM) has been developed for the repair, overlay or joining of nickel and cobalt-based high-temperature alloys. This process involves mechanical cleaning, followed by the application and consolidation of a filler metal powder, which has substantially the same composition as the base metal, and producer joints with mechanical properties similar to

K. A. Ellison; P. Lowden; J. Liburdi

1994-01-01

279

Physical Characteristics of Fire-Extinguishing Powders.  

National Technical Information Service (NTIS)

Powders are known to be highly efficient fire-extinguishing agents. There are powders available that, on both weight and volume bases, are more efficient than Halon 1301 as fire-extinguishing agents. A project was undertaken to examine several powders by ...

A. E. Finnerty L. J. VandeKieft A. Drysdale

1997-01-01

280

Spherical particles for automotive powder coatings  

Microsoft Academic Search

Clear powder coatings that consist of spherical particles with a narrow particle size distribution were produced via a suspension method that involves the agglomeration and unification of smaller particles. These powder coatings have the advantages of excellent powder flowability and high transfer efficiency. This behavior is attributable to the spherical particle shape and absence of finer particles. This production method

Haruhiko Satoh; Yutaka Harada; Shannon Libke

1997-01-01

281

21 CFR 73.1647 - Copper powder.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 2013-04-01 false Copper powder. 73.1647 Section 73.1647...FROM CERTIFICATION Drugs § 73.1647 Copper powder. (a) Identity. (1) The color additive copper powder is a very fine free-flowing...

2013-04-01

282

Implementation of the Powder Dispensing of Digitization  

Microsoft Academic Search

Dose uniformity is one of the important factors in evaluation of microfeeding of fine powders. This paper describes a method for metering and dispensing the fine metal powders. The principle of the powder dispensing of digitalization is distinct from ultrasonic microfeeding, and it not only achieved continuous feeding, but also guaranteed dose uniformity. To avoid the relative movement and with

Xin Geng; Li-ya Hou; Wei-yi Zhang

2010-01-01

283

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

284

Wetter for fine dry powder  

DOEpatents

A system for wetting fine dry powders such as bentonite clay with water or other liquids is described. The system includes a wetting tank for receiving water and a continuous flow of fine powder feed. The wetting tank has a generally square horizontal cross section with a bottom end closure in the shape of an inverted pyramid. Positioned centrally within the wetting tank is a flow control cylinder which is supported from the walls of the wetting tank by means of radially extending inclined baffles. A variable speed motor drives a first larger propeller positioned immediately below the flow control cylinder in a direction which forces liquid filling the tank to flow downward through the flow control cylinder and a second smaller propeller positioned below the larger propeller having a reverse pitch to oppose the flow of liquid being driven downward by the larger propeller.

Hall, James E. (131 Arkansas Ave., Oak Ridge, TN 37830); Williams, Everett H. (198 Hillside Road, Oak Ridge, TN 37830)

1977-01-01

285

Peritonitis from Starch Glove Powder  

PubMed Central

Contamination of surgical wounds by starch glove powders has produced peritoneal inflammation and adhesions in many patients. Some have required surgical operation because of possible infection, others because of obstruction of the intestine. Resolving granulomas and fibrosis have been observed as incidental asymptomatic lesions in some patients during reoperation for other conditions. Starch granules are probably capable of producing inflammation in any patient, and the degree is believed to be related to the amount of starch present. Care in removing glove powder from gloves before they are worn in an operation will diminish or eliminate the problem. Removal can be accomplished by rubbing the gloves with a moist sterile towel or laparotomy tape. ImagesFigure 1.Figure 2.

Dutra, Frank R.; Jensen, C. David

1972-01-01

286

Growth and characterization of nearly perfect lithium para nitrophenolate nonlinear optical single crystal  

NASA Astrophysics Data System (ADS)

There has been considerable interest in the synthesis of semi organic NLO materials recently with excellent second order optical nonlinearities. Perfect single crystals are essential for fair device performance. Single crystals of title compound were grown by slow evaporation method. The perfection of the grown crystal has been studied by the high resolution x-ray diffraction method. NMR spectral analysis has been studied. NLO properties and thermal properties were found by Kurtz powder Technique and TG/DTA analyses respectively.

Mahadevan, M.; Jagannathan, K.; Anandan, P.; Ramachandran, K.

2013-06-01

287

Pressure sintering of powder materials  

Microsoft Academic Search

Rheological models for pressure sintering of powder materials are described. The rheological models of deformable bodies and\\u000a the associated dynamic deformation theory for porous bodies based on the energy conservation law enable a quantitative description\\u000a of their densification under impulse and static hot pressing as well as hot forging using crank presses. The simulation of\\u000a compaction of porous metals shows

M. S. Kovalchenko

2011-01-01

288

Composition of reactive powder concretes  

Microsoft Academic Search

Development of an ultra-high strength ductile concrete designated RPC (Reactive Powder Concrete), was made possible by the application of a certain number of basic principles relating to the composition, mixing and post-set heat curing of the concrete.RPC 200, which can be used under job site conditions similar to those for conventional high performance concretes, can be used in the construction

Pierre Richard; Marcel Cheyrezy

1995-01-01

289

Shock compaction of molybdenum powder  

Microsoft Academic Search

Shock recovery experiments carried out in the 9 to 12 GPa range on 1.4 distension Mo appear adequate to compact to full density (< 45 ..mu..m) powders. However, the stress levels 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 ..mu..m particles. The

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

1983-01-01

290

Direct preparation of BaTiO 3 powders from titanium metal by anodic oxidation under hydrothermal conditions  

Microsoft Academic Search

Barium metatitanate, BaTiO3, is a representative ferroelectric and piezoelectric material. Its usefulness has attracted much attention in electronics and other branches of engineering as well as in ceramics. A variety of techniques have therefore been developed for preparing high-purity fine BaTiO3 powders. In the most conventional method, BaTiO3 powders have been prepared by solid-state reactions from powder precursors [1]. However,

Seung Eul Yoo; Masahiro Yoshimura; Shigeyuki S?miya

1989-01-01

291

Study on the Burning Characteristics of AP\\/Al\\/HTPB Composite Solid Propellant Containing Nano-Sized Ferric Oxide Powder  

Microsoft Academic Search

This study mainly explores the burning characteristics of AP\\/Al\\/HTPB composite solid propellant containing nano-sized ferric oxide (Fe2O3) powder. Firstly, the appropriate dispersed technique is applied to prepare the propellant samples containing the ferric oxide (micro-sized and\\/or nano-sized) powder and then the scanning electron microscope (SEM) is used to observe the dispersed effect of ferric oxide powder in the propellant samples.

Kai-Tai Lu; Tsung-Mao Yang; Jin-Shuh Li; Tsao-Fa Yeh

2012-01-01

292

Fractal and agglomeration behavior in Gd and Sm doped CeO 2 nano-crystalline powders  

Microsoft Academic Search

Nanocrystalline Gd, Sm doped ceria powders were synthesized by a combustion technique, using glycine as the fuel. These powders, after calcination at 600C, were characterized by powder X-ray diffraction and were found to be phase pure. The crystallite sizes, as calculated from X-ray line broadening were in the range of 1113nm, which were in close agreement with those obtained from

S. V. Chavan; P. U. Sastry; A. K. Tyagi

2008-01-01

293

Microwave absorption properties of SrFe 12O 19\\/ZnFe 2O 4 composite powders  

Microsoft Academic Search

The composite powders with different weight ratios of strontium hexaferrite to zinc ferrite were prepared using solgel technique. The crystal structure, morphology and microwave absorption properties of the composite powders were investigated with XRD, FESEM, TEM and vector network analyzer. The results show that the composite powders consist of SrFe12O19 and ZnFe2O4 phases and the individual particles are typically 100200nm

Na Chen; Guohong Mu; Xifeng Pan; Keke Gan; Mingyuan Gu

2007-01-01

294

The influence of HVAF powder feedstock characteristics on the sliding wear behaviour of WCNiCr coatings  

Microsoft Academic Search

In this paper, the HVAF technique was used to deposit coatings with mechanically milled nano and micron blended WCNiCr powders. The mechanically milled nano powder was produced using the high-energy ball milling process. Due to low particle heating and high particle velocity in the HVAF process, the fine and dense microstructure of the mechanically milled powder remains almost unchanged after

Shenglin Liu; Dongbai Sun; Zishuan Fan; Hong-ying Yu; Hui-min Meng

2008-01-01

295

Analysis of the headspace composition of smokeless powders using GCMS, GC-?ECD and ion mobility spectrometry  

Microsoft Academic Search

Smokeless powder additives are usually detected from an extraction of post-blast residues or unburned powder particles followed by chromatographic analyses. This work presents the first comprehensive study of the detection of volatile and semi-volatile additives of smokeless powders using solid phase microextraction (SPME) as a sampling and pre-concentration technique. The goal of this study is to generate a list of

Monica Joshi; Kia Rigsby; Jose R. Almirall

2011-01-01

296

Amorphous rare earth magnet powders  

SciTech Connect

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

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

1996-08-01

297

A powder particle size effect on ceramic powder based separator for lithium rechargeable battery  

Microsoft Academic Search

To improve the thermal stability of separators for lithium batteries, we have developed heat-resistant separator films based on ceramic powder. These ceramic powder based separators (CPS) consist of ceramic powder with binder resin. We used two different particle size powders of aluminum oxide (0.01 or 0.3?m). By mixing ceramic powder and resin at an appropriate content ratio, both types of

Daigo Takemura; Shigeru Aihara; Kouji Hamano; Makiko Kise; Takashi Nishimura; Hiroaki Urushibata; Hajimu Yoshiyasu

2005-01-01

298

Preliminary attempt at sintering an ultrafine alumina powder using microwaves. Master's thesis  

SciTech Connect

A commercially available microwave oven was used to sinter ultrafine alumina powders (0.02 - 0.05 micrometers particle size) with and without CaO sintering aid. The oven was modified by inserting a thermocouple probe through the bottom housing, and thoroughly insulating the interior with insulating material. The oven was placed in a glove box and filled with argon to prevent degradation of the thermocouple, and oxidation of the powdered graphite susceptor. Heating rates of 50-75 Deg C/sec with a maximum temperature of 1575 Deg C were obtained. Limited success in sintering of the the powder compacts was achieved in this preliminary effort. The microstructures of the sintered products were examined by scanning electron microscopy. It was concluded that further work is necessary to develop this technique into one which can be used for the routine sintering of fine powdered ceramic material. A review of the literature on microwave sintering of ceramic powders is also reported.

Alhambra, E.M.

1994-09-01

299

Titanium alloy powder preparation for selective laser sintering  

Microsoft Academic Search

Selective laser sintering (SLS) is a solid freeform fabrication process whereby a part is built layerwise by scanning a powder bed. The processability of metal powder varies depending on the state of the powder prior to SLS. A powder thermal pre-treatment was developed which involved degassing the powder at an elevated temperature in a vacuum. Without powder thermal pre-treatment, the

B. Engel; D. L. Bourell

2000-01-01

300

Development of Spray Dried Liposomal Dry Powder Inhaler of Dapsone  

Microsoft Academic Search

This investigation was undertaken to evaluate practical feasibility of site specific pulmonary delivery of liposomal encapsulated\\u000a Dapsone (DS) dry powder inhaler for prolonged drug retention in lungs as an effective alternative in prevention of Pneumocystis carinii pneumonia (PCP) associated with immunocompromised patients. DS encapsulated liposomes were prepared by thin film evaporation\\u000a technique and resultant liposomal dispersion was passed through high

Mahavir Chougule; Bijay Padhi; Ambikanandan Misra

2008-01-01

301

Production of fine powders by ultrasonic standing wave atomization  

Microsoft Academic Search

Ultrasonic standing-wave atomization using two sonotrodes (20 kHz), both oscillating against each other, allows the disintegration of extremely viscous fluids (synthetic resins, highly concentrated suspensions) or fluids with high surface tension (metal melts) into narrow-sized, extremely small droplets and therefrom the production of fine spherical powders. The fundamentals of this new technique as well as its application in viscous fluid

Klaus Bauckhage; O. Andersen; S. Hansmann; W. Reich; P. Schreckenberg

1996-01-01

302

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

SciTech Connect

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

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

2000-04-24

303

Dry powder segregation and flowability: Experimental and numerical studies  

NASA Astrophysics Data System (ADS)

Dry powder blending is a very important industrial and physical process used in the production of numerous pharmaceutical dosage forms such as tablets, capsules, and dry powder aerosols. Key aspects of this unit operation are process monitoring and control. Process control is particularly difficult due to the complexity of particle-particle interactions, which arise from the adhesion/cohesion characteristics of interfaces and morphological characteristics such as particle size, shape, and dispersity. The effects of such characteristics need to be understood in detail in order to correlate individual particle properties to bulk powder properties. The present dissertation numerically and experimentally quantifies the mixing process to rationalize particle-particle interactions. In particular, near infrared spectroscopy (NIRS) was used to non-invasively characterize in real-time the blending processes and thus investigate the dynamics of blending under different operating conditions. A novel image analysis technique was developed to quantify the scale of segregation from images obtained non-destructively via near infrared chemical imaging (NIR-CI). Although NIR-CI data acquisition times are too long for real-time data collection, NIR-CI has an advantage, in that it provides the spatial distribution of the drug. Therefore, NIRS and NIR-CI are complementary techniques for investigating the complex process of blending dry powders and assessing end-product quality. Additionally, the discrete element method was used to investigate the effect of powder cohesion on the packing fraction. Simulations indicated an exponential relationship between the random loose packing fraction and cohesive forces. Specifically, the packing fraction decreased asymptotically with increased ratio of cohesive force to particle weight. Thus, increasing this force ratio above a critical value has negligible impact on the packing fraction. Such result directly impacts the Hausner ratio flowability measurement, which is directly related to the packing fraction. Two commonly used tests were compared to assess their utility: the rotational split-cell shear cell test and the Hausner ratio. The Hausner ratio proved to be better suited for characterizing the flowability of unconsolidated powders than the splitring shear cell. Results demonstrate that the optimal flowability test depends on the powder properties and the environment under which flow will be induced.

Ely, David R.

304

Interparticle force based methodology for prediction of cohesive powder flow properties  

NASA Astrophysics Data System (ADS)

The transport and handling of powders are key areas in the process industry that have a direct impact on the efficiency and/or the quality of the finished product. A lack of fundamental understanding of powder flow properties as a function of operating variables such as relative humidity, and particle size, leading to problems such as arching, rat-holing and segregation, is one the main causes for unscheduled down times in plant operation and loss of billions of dollars in revenues. Most of the current design strategies and characterization techniques for industrial powders are based on a continuum approach similar to the field of soil mechanics. Due to an increase in complexity of the synthesis process and reduction in size of powders to the nanoscale, the surface properties and inter particle forces play a significant role in determining the flow characteristics. The use of ensemble techniques such as direct shear testing to characterize powders are no longer adequate due to lack of understanding of the changes in the property of powders as a function of the major operating variables such as relative humidity, temperature etc. New instrumentation or techniques need to be developed to reliably characterize powder flow behavior. Simultaneously, scalability of the current models to predict powder flow needs to be revisited. Specifically, this study focuses on the development of an inter particle force based model for predicting the unconfined yield strength of cohesive powders. To understand the role of interparticle forces in determining the strength of cohesive powders, the particle scale interactions were characterized using Atomic Force Microscopy (AFM), contact angle, surface tension, and coefficient of friction. The bulk scale properties such as unconfined yield strength, packing structure, and size of the shear zone were also investigated. It was determined that an interparticle force based model incorporating the effect of particle size and packing structure leads to a reasonable prediction of the bulk strength of cohesive powders. Additionally, the role of particle size distribution and liquid distribution in the powder was considered. The findings of this research should be helpful to the practitioners in providing reliable input for the design of cohesive powder flow and handling equipment.

Esayanur, Madhavan Sujatha Sarma

305

The effects of powder properties on in-flight particle velocity and deposition process during low pressure cold spray process  

Microsoft Academic Search

In cold spray process, impacting velocity and critical velocity of particles dominate the deposition process and coating properties for given materials. The impacting velocity and critical velocity of particles depend on the powder properties and cold spray conditions. In the present study, the in-flight particle velocity of copper powder in low pressure cold spraying was measured using an imaging technique.

Xian-Jin Ning; Jae-Hoon Jang; Hyung-Jun Kim

2007-01-01

306

Determination of the Adsorption Isotherm of Vapor-Phase Mercury Chloride on Powdered Activated Carbon Using Thermogravimetric Analysis  

Microsoft Academic Search

This study investigated the use of thermogravimetric analysis (TGA) to determine the adsorptive capacity and adsorption isotherm of vapor-phase mercury chloride on powdered activated carbon (PAC). The technique is commonly applied to remove mercury-containing air pollutants from gas streams emitted from municipal solid waste incinerators. An alternative form of powdered activated carbon derived from a pyrolyzed tire char was prepared

Hsun-Yu Lin; Chung-Shin Yuan; Wei-Ching Chen; Chung-Hsuang Hung

2006-01-01

307

Focused ion beam fabrication of field-ion microscope specimens from mechanically milled pearlitic steel powder.  

PubMed

Sharp needle-like specimens for atom-probe field-ion microscope (APFIM) analysis have been prepared successfully from mechanically milled pearlitic steel powders. Mechanically milled powders were packed in a stainless steel tube with carbonyl steel powders and then consolidated by sheath cold-rolling to obtain a bulk composite. A small square rod was cut out from the bulk and electropolished to a blunt needle. It was then fabricated to a nanometre-sized needle by a focused ion beam technique using an annular gallium ion beam. The tip radius of the specimen was <50 nm, which is suitable for use in APFIM. PMID:15582960

Ohsaki, Satoru; Hono, Kazuhiro; Hidaka, Hideyuki; Takaki, Setsuo

2004-01-01

308

Synthesis and properties of CaAlO-coated AlO microcomposite powders  

Microsoft Academic Search

Novel microcomposite powders, consisting of inert cores (α-AlO) surrounded by reactive cement-based coatings (CaAlO), were synthesized by a modified Pechini process. The evolution of the crystalline CaAlO phase during calcination was studied using multiple analytical techniques, including DRIFTS, ¹³C and ²⁷Al MAS FT-NMR, and XRD, for both pure CaAlO and CaAlO-coated AlO precursor powders. In both powders, decomposition proceeded via

Priyadarshi G. Desai; Zhengkui Xu; Jennifer A. Lewis

1995-01-01

309

Hafnia powders (HfO{sub 2}): Elaboration and characterization by transmission electron microscopy  

SciTech Connect

HfO{sub 2} is very similar to ZrO{sub 2}; the powder preparation routes developed for ZrO{sub 2} ceramics are equally applicable to HfO{sub 2} ceramics. Cubic HfO{sub 2} stabilized by yttrium oxide was prepared at low temperature (<1000{degrees}C) by oxalic precursors pyrolysis or via molten salts reaction. The powders obtained were characterized by X-ray diffraction, granular distribution, and transmission electron microscopy. TEM has been proved to be the best technique to characterize the powder size homogeneity, chemical composition, and crystallographic structure.

Lakhlifi, A.; Satre, P.; Roubin, M. [Universite de Toulon, La Garde (France)] [and others

1995-11-01

310

Powder metallurgical processing of magnetostrictive materials based on rare earth-iron intermetallic compounds  

SciTech Connect

Procedures are described for fabrication of high density rare earth-iron magnetostrictive compounds by powder metallurgical techniques. The fabrication involves a sequence of steps which includes preparing the pre-alloyed compounds, pulverizing them into a fine powder, compacting in suitable sizes and shapes, and sintering. Samples prepared by these procedures are carefully characterized by scanning electron microscopy, x-ray diffraction, dilatometry, and magnetic measurements. Process steps are found to exert important influences upon densities, microstructure and magnetic properties attained after densification. Investigations on a number of these process steps, including milling time and medium, sintering, and magnetic powder alignment are described.

Malekzadeh, M.

1978-01-01

311

Effect of precursor powder on the properties of silver-clad Bi-2223 superconducting wires and tapes  

SciTech Connect

Superconductor precursor powder was ground in a planetary mill using various combinations of grinding container, balls and carrier (dry and wet). Dry milling was found to be more effective than wet milling for reducing particle size irrespective of container and ball materials used. Serious Si contamination was observed in powders milled using agate grinding material. Some C from polypropylene container was found after milling, but no Zr from YSZ balls. Effect of powder particle size, initial packing density and various powder preparation techniques on the properties of Bi2223/Ag tapes was systematically investigated in terms of high-T{sub c} phase formation, microstructure and critical current density (J{sub c}).

Guo, Y.C.; Li, J.N.; Liu, H.K. [Univ. of Wollongong (Australia)] [and others

1997-06-01

312

Growth and characterization of NLO based L-arginine maleate dihydrate single crystal  

NASA Astrophysics Data System (ADS)

Single crystals of L-arginine maleate dihydrate (LAMD) were successfully grown from aqueous solution by solvent evaporation technique. As-grown crystals were analyzed by different instrumentation techniques such as X-ray powder diffraction (XRD), Fourier transform infrared (FTIR) spectra and UV-vis near infrared (NIR) transmittance spectra. Thermal behavior has been studied with TGA/DTA analyses. The optical second harmonic generation (SHG) conversion efficiency of LAMD was determined using Kurtz powder technique and found to be 1.5 times that of KDP.

Baraniraj, T.; Philominathan, P.

2010-01-01

313

Preparation of nickel-coated powders as precursors to reinforce MMCs  

Microsoft Academic Search

The preparation of nickel-coated ceramic particles as precursors for MMC fabrication was studied. Al2O3 and SiC powders of three different particle sizes were successfully coated with Ni using an electroless metal plating technique. Uniform and continuous nickel films were deposited on both, alumina and silicon carbide powders, with a final composition ranging from 1.6 to 1.9wt% phosphorus, 1821wt% of metallic

C. A. Leon; R. A. L. Drew

2000-01-01

314

Characterization and densification of lanthana-zirconia powders prepared by high temperature hydrolysis  

Microsoft Academic Search

Zirconia-lanthana powders containing 4.5, 7, 10, 15 and 20 mol % La2O3 were prepared by hydrolysis. The hydrolysis process was carried out in a laboratory stainless steel autoclave for their equivalent\\u000a hydroxides for 2 h at 200 C. The powders were investigated using X-ray diffraction, infrared spectrometry, and transmission\\u000a electron microscopy techniques. No other phases except the cubic phase zirconia

S. B. Hanna; N. M. Ghoneim

1986-01-01

315

Modified Pechini synthesis of La, Ce, and Pr orthophosphates and characterization of obtained powders  

Microsoft Academic Search

In this study, lanthanum, cerium, and praseodymium orthophosphates were synthesized by the modified Pechini method. The compounds\\u000a were analyzed using XRD, TG\\/DSC, FTIR methods, and the isothermal nitrogen adsorption technique. The results showed that mesoporous\\u000a and nanocrystalline powders can be synthesized by this method. Moreover, due to the limited formation of lanthanide polyphosphates\\u000a on the surface of the powders the

Aleksandra Matraszek; Ewa Radominska; Irena Szczygiel

2011-01-01

316

UO powder from uranyl-loaded cation exchange resin  

Microsoft Academic Search

UO powder has been produced from uranyl-loaded cation exchange resin with density, particle size distribution, and grain size suitable for powder metallurgy fabrication of reactor fuel tubes with Al-UO cores. Macroporous sulfonate resin in granular form is used in the process. Resin conversion techniques that were evaluated include batch, rotary, and fluidized bed calcination. 2 refs., 16 figs.

1985-01-01

317

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

Microsoft Academic Search

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,\\u000a molten droplets following impulse atomization. This produces a fine, homogeneous, dendritic microstructure within the alloy\\u000a granules. Following consolidation via hot pressing, the microstructure consists mostly of an Al matrix with fine CuAl2 particles and

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

2000-01-01

318

Gold powder: Its preparation & application as described in ancient Sanskrit texts  

Microsoft Academic Search

In this article the origin and development of the technology of gold powder in ancient India is described on the basis of\\u000a the literary evidence cited in various Sanskrit texts. The applications of gold powder as described in these texts are also\\u000a discussed.\\u000a \\u000a \\u000a Basically two techniques mechanical comminution and chemical methods were used in Indian antiquity for making

R. K. Dube

1991-01-01

319

Superhydrophobic or superhydrophilic surfaces regulated by micro-nano structured ZnO powders  

Microsoft Academic Search

The present study demonstrates a simple technique to decorate a surface for superhydrophobic or superhydrophilic properties by randomly coating an inorganic oxides powder. The superior properties are stable in air for more than half a year. The particulates of the powder are made from aligned single crystalline ZnO nanorods, which aggregate to microspheres with (0?0?0?1) ends pointed outside of the

Xingfu Zhou; Xuefeng Guo; Weiping Ding; Yi Chen

2008-01-01

320

Photoelectrochemical behaviour of a dye-grafted nanocrystalline SnO 2 powder  

Microsoft Academic Search

A perylene-based dye was synthesized and covalently bound to undoped SnO2 nanosized powder. Because of the grafted dye, film sintering is not a straightforward process. In a preliminary step, it is proposed to check the photoactivity of this new powdered material directly by means of the cavity microelectrode technique under green or blue laser illumination through an optical microscope. Taking

H. Cachet; V. Vivier; T. Toupance

2004-01-01

321

Purification of silicon powder by the formation of thin porous layer followed byphoto-thermal annealing  

PubMed Central

Porous silicon has been prepared using a vapor-etching based technique on a commercial silicon powder. Strong visible emission was observed in all samples. Obtained silicon powder with a thin porous layer at the surface was subjected to a photo-thermal annealing at different temperatures under oxygen atmosphere followed by a chemical treatment. Inductively coupled plasma atomic emission spectrometry results indicate that silicon purity is improved from 99.1% to 99.994% after annealing at 900C.

2012-01-01

322

Phase and morphology evolution of magnesium niobate powders synthesized by solid-state reaction  

Microsoft Academic Search

Magnesium niobate (MgNb2O6; MN) powders have been prepared and characterized by TG-DTA, XRD, SEM and EDX techniques. The effect of calcination temperature, dwell time and heating\\/cooling rates on phase formation, morphology and chemical composition of the powders are examined. The calcination temperature and dwell time have been found to have a pronounced effect on the phase formation of the calcined

S Ananta

2004-01-01

323

Synthesis, formation and characterization of Mg 4Nb 2O 9 powders  

Microsoft Academic Search

Magnesium niobate (Mg4Nb2O9) powders have been prepared and characterized by thermogravimetric and differential thermal analysis (TGDTA), X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX) techniques. The effect of calcination temperature, dwell time and heating\\/cooling rates on phase formation, morphology and chemical composition of the powders are examined. The calcination temperature and dwell time have been found to

S Ananta

2004-01-01

324

Materials control and d.c. electroluminescence in ZnS:Mn, Cu, Cl powder phosphors  

Microsoft Academic Search

The preparation and d.c. electroluminescent properties of two types of powder phosphor are described. The first type is prepared by a slurrying technique in which the activators are added to pre-fired ZnS powder (post activation), and the second type involves the addition of the activators during the precipitation of the ZnS (simultaneous activation). Both types may subsequently be copper coated

A Vecht; N J Werring; R Ellis; P J F Smith

1969-01-01

325

Sintering of bimodal Y 2o 3-stabilized zirconia powder mixtures with a nanocrystalline component  

Microsoft Academic Search

Y2O3 - stabilized zirconia powders with average particle size of 10 nm and 430 nm were used to prepare bimodal powder mixtures by ultrasonic, ball milling and chemical precipitation techniques. Compacts were sintered between 1000C to 1340C for 10 min, 1 and 5h. Germans packing model was used to describe the observed green and sintered density as well as to

M Moskovits; B. G Ravi; R Chaim

1999-01-01

326

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

PubMed

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

Ning, C Q; Zhou, Y

2002-07-01

327

Thixoforming of Stellite Powder Compacts  

NASA Astrophysics Data System (ADS)

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

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

2007-04-01

328

Thixoforming of Stellite Powder Compacts  

SciTech Connect

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

Hogg, S. C. [Institute of PolymerTechnology and Materials Engineering, Loughborough University, Loughborough, LE11 3TU (United Kingdom); Atkinson, H. V. [Department of Engineering, University of Leicester, University Rd., Leicester LE1 7RH (United Kingdom); Kapranos, P. [Department of Engineering Materials, University of Sheffield, Mappin Street, Sheffield S1 3JD (United Kingdom)

2007-04-07

329

Selective laser sintering of amorphous metal powder  

Microsoft Academic Search

For the first time, selective sintering of amorphous PtCuNiP powder with a pulsed Nd:YAG laser has been studied. Upon pulsed interaction, the grains melt only superficially to build necks between the grains. Depending on the laser parameters, the sintered material can be crystallized or retained amorphous. By contrast with crystalline powder, laser sintering of amorphous powder is achieved at substantially

P. Fischer; A. Blatter; V. Romano; H. P. Weber

2005-01-01

330

Process for the synthesis of iron powder  

DOEpatents

A process for preparing iron powder suitable for use in preparing the iron-potassium perchlorate heat-powder fuel mixture used in thermal batteries, comprises preparing a homogeneous, dense iron oxide hydroxide precipitate by homogeneous precipitation from an aqueous mixture of a ferric salt, formic or sulfuric acid, ammonium hydroxide and urea as precipitating agent; and then reducing the dense iron oxide hydroxide by treatment with hydrogen to prepare the iron powder.

Welbon, William W. (Belleair, FL)

1983-01-01

331

Magnetic properties of polymer bonded nanocrystalline powder  

Microsoft Academic Search

Purpose: The aim of this paper was to develop a dielectromagnetic based on nanocrystalline Fe73.5Cu1Nb3Si13.5B9 powder bonded with organo-silicon polymer and to investigate the powder particle size and content of polymer response of the magnetic properties. Design\\/methodology\\/approach: The dynamic magnetic properties at the frequency range from 50 Hz up to 100 kHz of nanocrystalline iron based powder cores were measured

P. Gramatyka; R. Nowosielski; P. Sakiewicz

332

Particle Structures of Encapsulated Milkfat Powders  

Microsoft Academic Search

Emulsions of milkfat (cream or anhydrous butteroil), carbohydrate (sucrose, modified starch or all-purpose flour), nonfat dry milk and mono- and di-glycerides as emulsifying agents were prepared and spray dried, yielding free-flowing powders containing 400, 500 or 600 g\\/kg milkfat. Structural features of the powders were evaluated by optical and scanning electron microscopy. Powder particles were generally spherical in shape, with

C. I. Onwulata; P. W. Smith; P. H. Cooke; V. H. Holsinger

1996-01-01

333

Process for the synthesis of iron powder  

DOEpatents

A process for preparing iron powder suitable for use in preparing the iron-potassium perchlorate heat-powder fuel mixture used in thermal batteries, comprises preparing a homogeneous, dense iron oxide hydroxide precipitate by homogeneous precipitation from an aqueous mixture of a ferric salt, formic or sulfuric acid, ammonium hydroxide and urea as precipitating agent; and then reducing the dense iron oxide hydroxide by treatment with hydrogen to prepare the iron powder. 2 figs.

Welbon, W.W.

1983-11-08

334

Process for the synthesis of iron powder  

DOEpatents

A process for preparing iron powder suitable for use in preparing the iron-potassium perchlorate heat-powder fuel mixture used in thermal batteries, comprises preparing a homogeneous, dense iron oxide hydroxide precipitate by homogeneous precipitation from an aqueous mixture of a ferric salt, formic or sulfuric acid, ammonium hydroxide and urea as precipitating agent; and then reducing the dense iron oxide hydroxide by treatment with hydrogen to prepare the iron powder.

Not Available

1982-03-06

335

Dilatometry of attrition milled nanocrystalline titanium powders  

Microsoft Academic Search

The sintering behavior of nanosized titanium powders was investigated by dilatometry. The nanosized Ti powders (40nm) were produced by the attrition milling of micron sized Ti powders (12?m) in Ar atmosphere. Sintering was carried out in Ar atmosphere in the temperature range of 4501250C for nanosized Ti and 6501250C for micron sized Ti by heating at 10C\\/min, up to the

Vikram V. Dabhade; B. B. Panigrahi; M. M. Godkhindi; T. R. Rama Mohan; P. Ramakrishnan

2006-01-01

336

Process for synthesizing compounds from elemental powders  

DOEpatents

A process for synthesizing intermetallic compounds from elemental powders. The elemental powders are initially combined in ratio a 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, B.H.; Wright, R.N.

1990-01-01

337

Process for synthesizing compounds from elemental powders  

DOEpatents

A process for synthesizing intermetallic compounds from elemental powders. The elemental powders are initially combined in ratio a 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, B.H.; Wright, R.N.

1990-12-31

338

Selective laser sintering of amorphous metal powder  

NASA Astrophysics Data System (ADS)

For the first time, selective sintering of amorphous PtCuNiP powder with a pulsed Nd:YAG laser has been studied. Upon pulsed interaction, the grains melt only superficially to build necks between the grains. Depending on the laser parameters, the sintered material can be crystallized or retained amorphous. By contrast with crystalline powder, laser sintering of amorphous powder is achieved at substantially lower pulse energies due to its low melting point. The obtained results are compared with previous results from selective laser sintering of titanium powder.

Fischer, P.; Blatter, A.; Romano, V.; Weber, H. P.

2005-02-01

339

Synthesis of neodymium-doped yttrium aluminum garnet (YAG) nanocrystalline powders leading to transparent ceramics  

Microsoft Academic Search

We report on the synthesis of Nd:YAG nanoparticles by the coprecipitation technique and the optimum conditions for the processing of transparent ceramics. The powders prepared by the coprecipitation technique display significantly less agglomeration of crystallites, indicating higher sinterability. The crystallite size dependence on the calcinations temperature suggests the optimum temperature of 1100C, at which phase purity of the YAG nanopowder

A. K. Pradhan; Kai Zhang; G. B Loutts

2004-01-01

340

Application of powder rheometer to determine powder flow properties and lubrication efficiency of pharmaceutical particulate systems  

Microsoft Academic Search

The objective of this study was to understand the behavior of particulate systems under different conditions of shear dynamics\\u000a before and after granulation and to investigate the efficiency of powder lubrication. Three drug powders, metronidazole, colloidal\\u000a bismuth citrate, and tetracycline hydrochloride, were chosen as model drugs representing noncohesive and cohesive powder systems.\\u000a Each powder was individually granulated with microcrystalline cellulose

Charu V. Navaneethan; Shahrzad Missaghi; Reza Fassihi

2005-01-01

341

Comparison of electrostatic fine powder coating and coarse powder coating by numerical simulations  

Microsoft Academic Search

Powder coating has several key advantages over liquid coating, and fine powder coating makes the surface finish quality comparable with liquid coating. This work reports on the numerical simulation of a fine powder-coating process in comparison with coarse powder coating, using a commercial computational fluid dynamic code, Fluent v6.1. The purpose of the study is to understand the gas and

U. Shah; C. Zhang; J. Zhu

2006-01-01

342

Preparation of ceramic powders based on titanium nitride on heating commercial titanium powder in air  

Microsoft Academic Search

Theoretical bases arepresented for preparing ceramic powders based on titanium and aluminum nitrides. The basic advantages\\u000a are formulated for self-propagating high-temperature synthesis of metal nitride powders in air compared with known preparation\\u000a methods. The main results are summarized and presented for preparing titanium nitride powder with combustion in air of cylindrical\\u000a and conical specimens of commercial titanium powder. The effect

Yu. I. Strokova; A. A. Gromov; V. I. Vereshchagin

2008-01-01

343

Radio frequency (rf) plasma spheroidized HA powders: powder characterization and spark plasma sintering behavior  

Microsoft Academic Search

The present study describes the synthesis of spheroidized hydroxyapatite (HA) powders using a radio frequency (rf) inductively coupled plasma (ICP) torch. The spheroidized powders were consolidated through a spark plasma sintering (SPS) system. The microstructure and crystallographic phases in the synthesized powders were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffractometry (XRD) and Raman spectrometry. Results

J. L. Xu; K. A. Khor; Y. W. Gu; R. Kumar; P. Cheang

2005-01-01

344

Properties of nickel base precipitation-hardening alloy powders and sintered parts from such powders  

Microsoft Academic Search

In Table 1 are listed the chemical compositions of the alloy powders investigated. The fine fraction (< 0.063 mm) content of the powders varied from 50 to 70 wt. %. The alloy KhN55VMTFKYu was chosen for determinations of the presence and character of solid solution strengthening phases. The powder of this alloy was pressed isostatically under a pressure of 150

I. A. Lavrent'ev; R. P. Shchegoleva

1974-01-01

345

Influences of different powders on the characteristics of particle charging and deposition in powder coating processes  

Microsoft Academic Search

This experimental study investigated the influences of two different powder systems (coarse and ultrafine) on particle charging and deposition characteristics during electrostatic powder coating processes. Results disclosed that, despite their differences in particle sizes, the two powders behave similarly in deposition process, commonly resulting in a cone-shaped deposited pattern in the inner portion of the substrate and an increase of

Xiangbo Meng; Hui Zhang

2009-01-01

346

Prospects of Nanodispersive Powder Applications in Surface Engineering Technologies  

NASA Astrophysics Data System (ADS)

General potentials of UDD (ultra dispersive diamond), NbC, WC, W, WC-Co, ZrO2, Al2O3, Si3N4, Co, nanosized powders in determining structure and properties of composite electrodes and coatings deposited by electrospark alloying (ESA) and thermoreactive electrospark surface strengthening (TRESS) techniques were considered. It was shown that an addition of refractory compound nanosized powder to the electrode material positively effects microstructure and tribological characteristic of ESA-coatings. Nanoparticles incorporated in the coating on grains boundaries serve as a lubricant for friction pairs. Wear resistant W-C-Co coatings with a friction coefficient below 0.15 were deposited by TRESS using nanopowders of Co and W. Nano- or microstructural coatings on the base of cemented carbides can be formed, depending on pulse discharge energy and frequency. Examples of beneficial industrial application of the coatings strengthened by nanosized particles were presented.

Levashov, E. A.; Kudryashov, A. E.; Vakaev, P. V.

347

Structural studies of magnesium nitride fluorides by powder neutron diffraction  

NASA Astrophysics Data System (ADS)

Samples of ternary nitride fluorides, Mg3NF3 and Mg2NF have been prepared by solid state reaction of Mg3N2 and MgF2 at 1323-1423 K and investigated by powder X-ray and powder neutron diffraction techniques. Mg3NF3 is cubic (space group: Pm3m) and has a structure related to rock-salt MgO, but with one cation site vacant. Mg2NF is tetragonal (space group: I41/amd) and has an anti-LiFeO2 related structure. Both compounds are essentially ionic and form structures in which nitride and fluoride anions are crystallographically ordered. The nitride fluorides show temperature independent paramagnetic behaviour between 5 and 300 K.

Brogan, Michael A.; Hughes, Robert W.; Smith, Ronald I.; Gregory, Duncan H.

2012-01-01

348

Transmission Electron Microscopy (TEM) investigations of ancient Egyptian cosmetic powders  

NASA Astrophysics Data System (ADS)

The processing technologies available during the time of ancient Egypt are of present concern to the field of Archaeology and Egyptology. Materials characterization is the best tool for establishing the processing history of archaeological objects. In this study, transmission electron microscopy (TEM) is used, in addition to other techniques, for phase identification and study of the microstructure and characteristic defect structures in ancient Egyptian cosmetic powders. These powders generally consist of a mix of Pb-containing mineral phases: galena (PbS), cerussite (PbCO3), and phosgenite (Pb2Cl2CO3), among others. Modern materials are fabricated according to recipes found in ancient texts to mimic the processing of ancient times and to compare with the archaeological specimens. In particular, a comparison between the dislocation structures of PbS crystals deformed in the laboratory and PbS from archaeological specimens from the collections of the Louvre Museum is presented .

Deeb, C.; Walter, P.; Castaing, J.; Penhoud, P.; Veyssire, P.

349

Density-permittivity relationships for powdered and granular materials  

SciTech Connect

Relationships between the permittivities of powdered or granular solid materials and their bulk densities (density of the air-particle mixture) are discussed. Linear relationships between functions of the permittivity and bulk density are identified that are useful in determining permittivity of solids from measurements of the permittivity of pulverized samples. The usefulness of several dielectric mixture equations for calculating solid material permittivity from measured permittivity of pulverized samples is also discussed. Results of testing linear extrapolation techniques and dielectric mixture equations on pulverized coal, limestone, plastics, and granular wheat and flour are presented. Recommendations are provided for reliable estimation of solid material permittivities or changes in permittivities of powdered and granular materials as a result of changes in their bulk densities.

Nelson, S.O. [USDA ARS, Athens, GA (United States). Russell Research Center

2005-10-01

350

Magnetic properties of mechanically alloyed Co-Ti powder  

NASA Astrophysics Data System (ADS)

An amorphous phase containing traces of non-transformed Co and Ti powders was obtained by mechanical alloying nominal compositions of Co67Ti33 and Co50Ti50 in a high-energy ball-mill. These alloys were prepared from elemental powders of Co and Ti. The heat treatment of Co67Ti33 at 573, 873 and 1173K crystallized nanoparticles of Co2Ti and Co3Ti compounds, while the same treatments conducted on Co50Ti50 resulted in the formation of Co2Ti and CoTi nanoparticles. The saturation magnetizations reached a maximum value in the amorphous state and they decreased when the temperatures of the heat treatment rose. Demagnetizing interparticle interaction effects were estimated through hysteresis loops and initial magnetization curves using the Fourier technique.

Martnez-Snchez, R.; Matutes-Aquino, J. A.; Ayala-Valenzuela, O.; De la Torre, S. D.

2002-07-01

351

The preparation and properties of glass powder reinforced epoxy resin  

Microsoft Academic Search

A sealing composites were prepared by mixing superfine glass powder and epoxy resin. The effect of active agent (stearate) on glass powder size and size distribution and the effect of surface treatment of the glass powder on the microstructure and the mechanical properties of glass powder\\/epoxy composites were investigated. Glass powder size was measured using a laser particle size analyzer.

Haifeng Wang; Wenjue Han; Haibing Tian; Yimin Wang

2005-01-01

352

Ignition of Titanium Powder Layers by Electrostatic Discharge  

Microsoft Academic Search

Titanium powder heating and ignition by an electrostatic discharge (ESD) or spark was investigated. The effect of powder layer thickness and morphology was determined. Ti powder was chosen for these experiments because it is commonly found in energetic formulations, used for materials preparation by self-propagating high-temperature synthesis, and is extensively used in powder metallurgy. Two Ti powders were used: spherical

Ervin Beloni; Edward L. Dreizin

2011-01-01

353

Light attrition of uranium dioxide powder  

Microsoft Academic Search

Sinterable uranium dioxide powders prepared through the ammonium diuranate route are prone to agglomeration causing difficulty in compaction and sintering. UO2 powder after light (short duration and low ball to charge ratio) attrition has been found to require lower compaction pressures and resulted in higher yields after sintering and finish grinding. Details of an in-house-built attritor are given. Experimental results

Palanki Balakrishna; B Narasimha Murty; D. V Ratnam; M Anuradha; C Ganguly

2003-01-01

354

Preparation of copper powder by glycerol process  

Microsoft Academic Search

A simple, least energy intensive, efficient, low temperature chemical process for the production of copper powder of narrow size distribution is described. It involves reduction of copper salts by glycerol under atmospheric conditions at a temperature below 240C. The powders produced by this process have been characterized by X-ray diffraction, chemical composition, BET surface area analysis and scanning electron microscopy.

Amit Sinha; B. P Sharma

2002-01-01

355

Creep densification of copper powder compact  

Microsoft Academic Search

Densification of metal powder under high temperature processing was investigated. Experimental data were obtained for copper powder under hot isostatic pressing, hot pressing and uniaxial creep compression. Theoretical calculations from the constitutive models by McMeeking and co-workers were compared with the experimental data. The agreements between experimental data and theoretical calculations are reasonably good when hydrostatic stress is dominant, but

M. C. Song; H. G. Kim; K. T. Kim

1996-01-01

356

Thermal plasma chemical synthesis of powders  

SciTech Connect

Thermal plasma processing has been increasingly used to synthesize submicron powders of high-purity ceramics and metals. The high temperatures generated with the plasma provide a vapor phase reaction zone for elements with high boiling points and refractory materials. An overview is presented on the general plasma technology used in synthesis and on the properties of plasma powders.

Vogt, G.J.; Newkirk, L.R.

1985-01-01

357

Slip casting and nitridation of silicon powder  

NASA Astrophysics Data System (ADS)

Powdered Silicon was slip-cast with a CaSO4 x 0.5H2O mold and nitrided in a N atm. containing 0 or 5 vol. % H at 1000 to 1420 deg. To remove the castings, the modeling faces were coated successively with an aq. salt soap and powdered cellulose containing Na alginate, and thus prevented the sticking problem.

Seiko, Y.

1985-03-01

358

Dynamic Powder Feeding System for Laser Cladding.  

National Technical Information Service (NTIS)

A powder feeding equipment has been designed for laser cladding. Tests have showed that the powder feeder is able to deliver a flow rate from 1.5 - 40 g/min, with a tolerance better than + or - 2% measured over a period of 30 seconds. This makes the feede...

T. A. Jensen

1990-01-01

359

Powder Lubricant Based on Molybdenum Disulfide.  

National Technical Information Service (NTIS)

This patent introduces a powder-like lubricant of molybdenum disulfide for machining of a cutting tool. To improve the cutting properties of the tool and increase its life, an addition of 15-25 percent sulfur to the powder lubricant is recommended.

S. V. Grekov

1969-01-01

360

PLANT TRIALS FOR POWDER PRIMING OF SMC  

Microsoft Academic Search

Based on the information generated at GM R&D Center, six SMC formulations were developed and produced by SMC suppliers and subsequently molded into automotive body panels for powder primer application readiness tests. The panels were evaluated in the lab for shrinkage, moisture absorption, adhesion to the conductive coating, and powder application. Based on the results, all six formulations were approved

Hamid G. Kia; Bhavesh Shah; Christina Hicks

361

Preparation of Silver Powder for Conductive Paste.  

National Technical Information Service (NTIS)

A novel technology for preparing silver flake powder has been studied. The solution containing KAg(CN)2 was reduced by suspension mixture of formaldehyde and benzaldehyde with surfactant TN, and luminous silver flake powder with an average particle size o...

L. Y. Chai H. Zhong H. Wu

1994-01-01

362

Sinterable Powders from Laser Driven Reactions.  

National Technical Information Service (NTIS)

Extremely fine, uniform ceramic powders have been synthesized from SiH4 NH3 and C2H4 gas phase reactants that are heated by absorbing optical energy emitted from a CO2 laser. Resulting Si, Si3N4 and SiC powders have been characteristics in terms of parame...

J. S. Haggerty

1982-01-01

363

Shock consolidation of powders: theory and experiment  

Microsoft Academic Search

A recently proposed model of shock consolidation of powders quantitatively predicts regimes of input energy and shock duration required to produce well-bonded compacts. A growing data base from shock experiments in which the shock wave and powder parameters of importance are controlled allows evaluation of the model. Rapidly solidified crystalline AISI 9310, and microcrystalline Markomet 3.11, as well as amorphous

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

1984-01-01

364

Caking phenomena in amorphous food powders  

Microsoft Academic Search

Caking of free-flowing powders during storage is a deleterious phenomenon that is ubiquitous in the feed, fertilizer and pharmaceutical industries, and of economical importance for low-moisture foods. Among other subjects related to caking of amorphous powders, the following aspects are reviewed in this article: (1) physical and morphological changes, and quantitative procedures to assess caking; (2) proposed mechanisms of caking

Jos M. Aguilera; Jos M. del Valle; Marcus Karel

1995-01-01

365

Electrical Resistivity of Metal Powder Aggregates  

Microsoft Academic Search

An equation for calculating the electrical resistivity of a compressed powder mass, consisting of oxide-coated metal particles, has been derived. In addition to the intrinsic interest of the problem, the proposed equation is useful for describing the very early stages of electrical sintering processes. The problem is approached in a new way, relating the actual powder system to an equivalent

J. M. Montes; F. G. Cuevas; J. Cintas

2007-01-01

366

Physical and dielectric properties of pharmaceutical powders  

Microsoft Academic Search

The limited availability of published physical and dielectric property data for pharmaceutical powders hinders the design of processing systems, particularly dryers. In this study, the physical properties (solubility and boiling point) and dielectric properties, in terms of temperature rise, dielectric constant, and dielectric loss factor, of selected pharmaceutical powders were measured. The pharmaceutical actives, paracetamol and aspirin, and selected common

C. M McLoughlin; W. A. M McMinn; T. R. A Magee

2003-01-01

367

Modeling nonelectrostatic and electrostatic powder coating  

Microsoft Academic Search

The effect of particle size, density, charge and air velocity on transfer efficiency, evenness and separation of mixtures during powder coating was investigated using modeling and experimentation. Electrostatic and nonelectrostatic coating was tested using 28, 234 and 342?m NaCl and 195?m starch powders. Transfer efficiency increased as particle size, density or charge increased or as air velocity decreased. Evenness increased

Shantanu Yousuf; Sheryl A. Barringer

2007-01-01

368

Poisoning with Veratrum-containing Sneezing Powders  

Microsoft Academic Search

1 Nine cases of accidental poisoning of children with sneezing powder are reported. Symptoms, besides sneezing, included gastrointestinal disturbances and syncope, whilst examination demonstrated bradycardia and hypotension.2 The powder, as supplied, carried no information on its constituents but Veratrum alkaloids were identified on analysis. The signs and symptoms observed were compatible with poisoning from these compounds.3 As a result of

P. Carlier; M.-L. Efthymiou; R. Garnier; J. Hoffelt; E. Fournier

1983-01-01

369

Chemistry and Technology of Metal Powders.  

National Technical Information Service (NTIS)

A new process for the preparation of finely divided metal powders has been used in preliminary studies on a number of metal powders. The metals that were examined were found to exhibit far superior reactivity to that described in the literature for these ...

R. D. Rieke

1977-01-01

370

Mating behaviors of Cydia pomonella (Lepidoptera: Tortricidae) as influenced by sex pheromone in electrostatic powder.  

PubMed

Entostat is an electrostatically charged wax powder that can adhere strongly to insect cuticle, making it an ideal carrier to deliver pheromone for pheromone-based confusion techniques. We investigated the attractiveness of Cydia pomonella (L.) (Lepidoptera: Tortricidae) males treated with pheromone-laden Entostat powder to naive conspecifics as well as mating behaviors of males after such treatment in a laboratory flight tunnel. Male moths exposed to Entostat containing 1% E,E-8,10-dodecadien-1-ol (codlemone) acquired and retained the largest amount of the powder and became more attractive as point sources to naive moths compared with those treated with powder containing 5 or 10% codlemone. All Entostat-exposed males remained as attractive as a 0.1-mg codlemone lure for up to 24 h in flight tunnel investigations. Male moth orientation to normally attractive sources of codlemone was completely disrupted directly after treatment with Entostat powder. Males' ability to orient to 0.1-mg lures recovered progressively over a 6-d postexposure interval; however, their responses never reached the levels observed with untreated control moths. Entostat-exposed moths retained detectable amounts of codlemone up to 4 d. Our laboratory flight tunnel results suggest that the mode of action of Entostat powder as an autodissemination control tactic may be due to creating both attractive false point sources after exposure to the powder as well as directly inhibiting contaminated males' capability to orient to pheromone. PMID:21309231

Huang, J; Stelinski, L L; Gut, L J

2010-12-01

371

Powder-lubricated piston ring development  

SciTech Connect

The overall objective of this program was to demonstrate the feasibility of a new particulate lubrication concept for reducing piston ring/cylinder liner wear in coal-water slurry-fueled diesels by replacing the present oil-lubricated system with powder lubrication that would utilize coal ash, either alone or in combination with another powder. The feasibility of this particular lubrication concept for reducing ring/liner wear was demonstrated in a series of experiments utilizing redesigned and properly selected components. Wear performance for suitable ring/liner materials lubricated with a powder that incorporates the abrasive ash particles was evaluated in terms of load capacity, friction, and rate of wear for the best combination of ring design, ring and liner materials, and powder constituents. In addition, the use of a powder-lubricated system in the upper portion of the cylinder isolated the particulates from the lower portions of the engine, thus further reducing engine wear. (VC)

Heshmat, H.

1991-06-01

372

Nanostructured GGG powders via gel combustion  

NASA Astrophysics Data System (ADS)

Polycrystalline nano-sized gadolinium gallium garnet (Gd3Ga5O12, GGG) powders were synthesized via a gel combustion method from a mixed solution of Ga(NO3)3, Gd(NO3)3 and citric acid. The evolution of phase composition and micro-structure of the powders were characterized by X-ray powder diffraction, thermogravimetry/differential thermal analysis and scanning electron microscopy. Well-crystallized, single phase GGG nano-sized powders could be obtained at the calcining temperature as low as 750 C for 2 h. No any intermediate phases formed during the calcining process. The resulting powders were well dispersed and had a relatively narrow size distribution with an average particle size of approximately 30 50 nm.

Li, Xianxue; Hu, Zhang-Gui; Li, Jiangtao

2007-03-01

373

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

374

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, L.G.

1979-08-29

375

Powder-lubricated piston ring development  

NASA Astrophysics Data System (ADS)

The overall objective of this program was to demonstrate the feasibility of a new particulate lubrication concept for reducing piston ring/cylinder liner wear in coal-water slurry-fueled diesels by replacing the present oil-lubricated system with powder lubrication that would utilize coal ash, either alone or in combination with another powder. The feasibility of this particular lubrication concept for reducing ring/liner wear was demonstrated in a series of experiments utilizing redesigned and properly selected components. Wear performance for suitable ring/liner materials lubricated with a powder that incorporates the abrasive ash particles was evaluated in terms of load capacity, friction, and rate of wear for the best combination of ring design, ring and liner materials, and powder constituents. In addition, the use of a powder-lubricated system in the upper portion of the cylinder isolated the particulates from the lower portions of the engine, thus further reducing engine wear.

Heshmat, H.

1991-06-01

376

Ultrasonic testing of reactive powder concrete.  

PubMed

Concrete is a critical material for the construction of infrastructure facilities throughout the world. Traditional concretes consist of cement paste and aggregates ranging in size from 6 to 25 mm that form a heterogeneous material with substantial compressive strength and a very low tensile strength. Steel reinforcement is used to provide tensile strength for reinforced concrete structures and as a composite the material is useful for structural applications. A new material known as reactive powder concrete (RPC) is becoming available. It differs significantly from traditional concrete; RPC has no large aggregates, and contains small steel fibers that provide additional strength and, in some cases, can replace traditional steel reinforcement. Due to its high density and lack of aggregates, ultrasonic inspections at frequencies 10 to 20 times that of traditional concrete inspections are possible. This paper reports on the initial findings of research conducted to determine the applicability of ultrasonic testing techniques for the condition assessment of RPC. Pulse velocities for shear and longitudinal waves and ultrasonic measurement of the modulus of elasticity for RPC are reported. Ultrasonic crack detection for RPC also is investigated. PMID:15055809

Washer, Glenn; Fuchs, Paul; Graybeal, Benjamin A; Hartmann, Joseph Lawrence

2004-02-01

377

Substantiating powder metal life methodologies for engines  

NASA Astrophysics Data System (ADS)

The application of powder metal (PM) superalloys in aircraft turbine engine rotating components is prompted by performance driven high strength and creep resistance requirements. Fine grain, precipitation strengthened nickel-base alloys such as IN100, Rene'95, and Rene'88DT meet these requirements up to operating temperatures in the 1200-1300F (649-704C) range. In addition to burst and deformation limits, design constraints include durability (fatigue) and damage tolerance (crack growth resistance) capability to insure reliability and safety. Fatigue life for these alloys can be influenced by inhomogeneities (inclusions) intrinsic to the microstructure as the result of processing, and by perturbations of the surface integrity during component manufacture and subsequent usage. Understanding of PM fatigue behavior and substantiation of life assessment methodology must appropriately recognize these potential influences. New testing, modeling, and analysis schemes are necessitated in engineering development programs addressing generation and validation of life prediction techniques for these materials. This paper outlines one approach to substantiating PM fatigue life prediction that attempts to recognize homogeneous fatigue initiation by incorporating probabilistic models and development testing methods that address material volume and component feature effects. Complications and limitations being addressed in ongoing work are discussed.

Domas, P. A.

1993-04-01

378

Spatially resolved spectral imaging of pharmaceutical powders  

NASA Astrophysics Data System (ADS)

Pharmaceutical initiatives use analytical tools to monitor powders flowing through granulating, blending, and tablet formation steps. Two critical parameters that drive the quality and efficiency of drugs are the concentration of actives in the tablet, and the dissolution properties of the tablet. In order to ensure that these are within the target design space, it is important that component concentrations, particle size distributions, and cluster size are monitored throughout the manufacturing process. Standard optical techniques detect scattered light from spots that encompass many components in the blend. Efforts to extract composition and blend uniformity based on chemometric analyses are complex and often intractable. A highly spatially resolved spectral imager could simplify the chemometrics if the effective spatial resolution can separate most particles from neighboring particles. The effective spatial resolution is a function of the incident spot size, multiple scattering events, and the collection optics. This paper assesses the degree of spectral mixing due to particle-particle scattering as a function of incident spot size. Our real-time optical design is enabled by a high spectral brightness supercontinuum source, a MEMs-based spectral scan mechanism, confocal spatial scanning optics, and high gain * bandwidth detection.

Carver, Gary E.; Rangwala, Sabbir

2008-08-01

379

Investigation of NIR hyperspectral imaging for discriminating melamine in milk powder  

NASA Astrophysics Data System (ADS)

Melamine (2,4,6-triamino-1,3,5-triazine) contamination of food has become an urgent and broadly recognized issue for which rapid and accurate identification methods are needed by the food industry. In this study, the feasibility and effectiveness of near-infrared (NIR) hyperspectral imaging was investigated for detecting melamine in milk powder. Hyperspectral NIR images (144 bands spanning from 990 to 1700 nm) were acquired for Petri dishes containing samples of milk powder mixed with melamine at various concentrations (0.02% to 1%). Spectral bands that showed the most significant differences between pure milk and pure melamine were selected, and two-band difference analysis was applied to the spectrum of each pixel in the sample images to identify melamine particles in milk powders. The resultant images effectively allowed visualization of melamine particle distributions in the samples. The study demonstrated that NIR hyperspectral imaging techniques can qualitatively and quantitatively identify melamine adulteration in milk powders.

Fu, Xiaping; Kim, Moon S.; Chao, Kuanglin; Qin, Jianwei; Lim, Jongguk; Lee, Hoyoung; Ying, Yibin

2013-05-01

380

21 CFR 866.1640 - Antimicrobial susceptibility test powder.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false Antimicrobial susceptibility test powder. ...Diagnostic Devices § 866.1640 Antimicrobial susceptibility test powder. (a) Identification. An antimicrobial susceptibility test powder...

2010-04-01

381

21 CFR 866.1640 - Antimicrobial susceptibility test powder.  

Code of Federal Regulations, 2010 CFR

...2009-04-01 2009-04-01 false Antimicrobial susceptibility test powder. ...Diagnostic Devices § 866.1640 Antimicrobial susceptibility test powder. (a) Identification. An antimicrobial susceptibility test powder...

2009-04-01

382

21 CFR 872.6660 - Porcelain powder for clinical use.  

Code of Federal Regulations, 2010 CFR

...2009-04-01 2009-04-01 false Porcelain powder for clinical use. 872.6660...Miscellaneous Devices § 872.6660 Porcelain powder for clinical use. (a) Identification. Porcelain powder for clinical use is...

2009-04-01

383

21 CFR 872.6660 - Porcelain powder for clinical use.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false Porcelain powder for clinical use. 872.6660...Miscellaneous Devices § 872.6660 Porcelain powder for clinical use. (a) Identification. Porcelain powder for clinical use is...

2010-04-01

384

Applicability of Washburn capillary rise for determining contact angles of powders/porous materials.  

PubMed

The Washburn capillary rise (WCR) technique has been widely utilized for determining contact angles of powders or porous materials; however, there are concerns regarding powder size and powder packing, especially for materials that exhibit large contact angle hysteresis. In this paper, some of these concerns were addressed. Due to the large water contact angle hysteresis on flat nylon 6/6 films, these films were ground into powders of different sizes and then used as model packing materials. The powders were packed in glass tubes to result in various packing structures that affected the penetration (i.e. advancing) rate of the test liquids. While all advancing contact angles obtained from WCR were found to be overestimated, more reasonable values were resulted when relatively large powders (e.g. 500-2000 ?m) were used to pack the tubes. With larger powders, the packing contained bigger voids and consequently lead to slower penetration rates of the liquids, hence a relatively smaller advancing contact angle. The smaller advancing contact angle obtained from the slower advancing rate was also observed by using the sessile drop method. To verify the applicability of using large powders (500-2000 ?m) for contact angle determination by using WCR, the advancing water contact angles of a bacterial cellulose/alginate composite sponge (BCA) with and without UV/ozone treatment were measured. The results showed that by using relatively large powders, WCR could be applied to obtain a reasonable advancing contact angle and assess the wettability change of complex porous materials. PMID:23484765

Kirdponpattara, Suchata; Phisalaphong, Muenduen; Newby, Bi-min Zhang

2013-01-29

385

Possibility of making polycrystalline diamond using high-temperature shock consolidation technique  

Microsoft Academic Search

High-temperature shock consolidation technique using converging underwater shock wave assembly is employed to compact diamond and its related material powders. Heating the powders gives the effects of softening and melting of powder surfaces, and the samples recovered at 1100 C shows high hardness which corresponds with the bulk materials to be consolidated. .

Kazuyuki Hokamoto; Masahiro Fujita; Sei-Ichiro Tanaka; Makoto Ayabe; Shigeru Itoh

2000-01-01

386

Possibility of making polycrystalline diamond using high-temperature shock consolidation technique  

NASA Astrophysics Data System (ADS)

High-temperature shock consolidation technique using converging underwater shock wave assembly is employed to compact diamond and its related material powders. Heating the powders gives the effects of softening and melting of powder surfaces, and the samples recovered at 1100 C shows high hardness which corresponds with the bulk materials to be consolidated. .

Hokamoto, Kazuyuki; Fujita, Masahiro; Tanaka, Sei-Ichiro; Ayabe, Makoto; Itoh, Shigeru

2000-04-01

387

High strain rate deformation microstructures of stainless steel 316L by cold spraying and explosive powder compaction  

NASA Astrophysics Data System (ADS)

Cold spraying is a new coating technique in which dense, tightly bonded coatings form only due to the high kinetic energy of impinging particles of the spray powder. These particles are still in the solid state during impact. Explosive powder compaction is a technique where powder is consolidated by a shock wave. In the shock front the powder is deformed under high strain rates, which under suitable conditions results in high-strength bonding of the particles. Thus, the microstructural features obtained by both techniques should be similar. This study correlates the microstructure of cold-sprayed 316L austenitic steel coatings in comparison to the microstructure of 316L samples obtained by explosive compaction. The results provide insight into the prevailing local deformation mechanisms, as well as into the physical background of observed phase transformations.

Borchers, C.; Schmidt, T.; Grtner, F.; Kreye, H.

2008-03-01

388

Aluminothermic powder boriding of steel  

NASA Astrophysics Data System (ADS)

Subject of thermodynamical analysis are the probable boron transport reactions, boron precipitation and boride forming in the reaction space with the use of aluminothermic boriding mixtures and activators such as NaF, NH 4F, Na 2O4BF 3 and (NH 4) 24BF 3. Aluminothermic boriding of carbon and alloyed steels have been carried out in a powder boriding mixture containing B 2O 320%, Al7%, Al 2O 372.5%, and (NH 4) 2O4BF 30.5% at a temperature of 1160 K and within a 6 h period. The thickness and the microhardness of the boride layers have been measured and a layer-by-layer chemical spectrum analysis has been made. The proposed structure of an aluminothermic mixture is determined to be suitable for boriding of low-carbon and low-alloyed steels. The boride layers obtained are distinguished for considerable thickness and high microhardness.

Uzunov, Nikolay; Ivanov, Radoslav

2004-03-01

389

Continuous production of titanium powder  

SciTech Connect

Although incremental improvements have been made to the Kroll process since its inception in 1948, the process in use today remains essentially the same batch process developed by Dr. Kroll and perfected by the U.S. Bureau of Mines. In this process, titanium tetrachloride (TiCl4) is reduced by magnesium to produce titanium metal. There are two major limitations to the Kroll process: (1) it is a batch process; and (2) the reduction of TiCl4 proceeds so rapidly that the sponge formed is an interlocking dendritic mass with inclusions of magnesium, magnesium salts and titanium subchloride that must undergo several purification steps before the metal is suitable for use. The Albany Research Center (ARC), formerly the U.S. Bureau of Mines, has investigated a new, continuous titanium metal production process in which a titanium powder is produced in a bath of molten salt. In this process, the rate of the reduction reaction was slowed and controlled by diluting the reactants with molten chloride salts. The diluted reactant streams were combined in a continuous stirred tank reactor, operated much like a crystallizer. New titanium metal forms on the already present small Ti particles. When the Ti particles become too large to remain suspended in solution, they fall to the bottom of the reactor and are removed. Initial experiments show promise but problems remain in obtaining the required purity and uniform particle size.

Gerdemann, Stephen J.; Oden, Laurence L.; White, Jack C.

1997-01-01

390

Dustiness of fine and nanoscale powders.  

PubMed

Dustiness may be defined as the propensity of a powder to form airborne dust by a prescribed mechanical stimulus; dustiness testing is typically intended to replicate mechanisms of dust generation encountered in workplaces. A novel dustiness testing device, developed for pharmaceutical application, was evaluated in the dustiness investigation of 27 fine and nanoscale powders. The device efficiently dispersed small (mg) quantities of a wide variety of fine and nanoscale powders, into a small sampling chamber. Measurements consisted of gravimetrically determined total and respirable dustiness. The following materials were studied: single and multiwalled carbon nanotubes, carbon nanofibers, and carbon blacks; fumed oxides of titanium, aluminum, silicon, and cerium; metallic nanoparticles (nickel, cobalt, manganese, and silver) silicon carbide, Arizona road dust; nanoclays; and lithium titanate. Both the total and respirable dustiness spanned two orders of magnitude (0.3-37.9% and 0.1-31.8% of the predispersed test powders, respectively). For many powders, a significant respirable dustiness was observed. For most powders studied, the respirable dustiness accounted for approximately one-third of the total dustiness. It is believed that this relationship holds for many fine and nanoscale test powders (i.e. those primarily selected for this study), but may not hold for coarse powders. Neither total nor respirable dustiness was found to be correlated with BET surface area, therefore dustiness is not determined by primary particle size. For a subset of test powders, aerodynamic particle size distributions by number were measured (with an electrical low-pressure impactor and an aerodynamic particle sizer). Particle size modes ranged from approximately 300 nm to several micrometers, but no modes below 100 nm, were observed. It is therefore unlikely that these materials would exhibit a substantial sub-100 nm particle contribution in a workplace. PMID:23065675

Evans, Douglas E; Turkevich, Leonid A; Roettgers, Cynthia T; Deye, Gregory J; Baron, Paul A

2012-10-12

391

Solidification characteristics of atomized white cast iron powders  

SciTech Connect

In recent years, interest in rapid solidification has been increasing and the subject has received extensive study. When compared with conventional solidification methods, rapid solidification technique produce microstructures with refined grain size, increased solubility of alloying element and impurities, and reduced levels of segregation. For many alloys, these effects lead to beneficial improvements in mechanical and other properties. White cast irons are commonly used engineering materials. However, cast iron components usually have a poor ductility and toughness under some severe conditions, for example, cyclical and impact loading. White cast irons are normally regarded as brittle materials. This lack of ductility is generally attributed to the presence of a large volume fraction of carbides which are distributed in a rather massive form within a ferrite matrix. Recent research shows that the large eutectic carbides in white cast iron can be refined through rapid solidification technology (RST). It is important to study the structural characterization of atomized powders since they have a direct effect on the properties of powder compacts. The present work is concerned with the morphology and microstructure of atomized low alloyed white cast iron powders.

Li Hong (Univ. of Strathclyde, Glasgow (United Kingdom) Univ. of Science and Technology Beijing (China)); Burdett, C.F. (Univ. of Strathclyde, Glasgow (United Kingdom)); Wang Youming (Univ. of Science and Technology Beijing (China))

1993-07-15

392

Influence of carrier on the performance of dry powder inhalers.  

PubMed

The aim of this work is to study carriers which can become alternatives to monohydrate lactose in dry powder inhalers and to consider particle parameters that influence adhesion between drug and carrier in dry powder inhalers. Different forms of mannitol, lactose and maltitol were mixed with either terbutaline sulphate or formoterol fumarate. The blends were submitted to different adhesion tests where drug detachment from the carrier was obtained either through mechanical vibration or by aspiration. Parameters like particle shape, roughness, amorphous content and cristalline form may affect interactions between drug and carrier. In our case, crystallized forms of the carrier offered lower adhesion but better release of the active ingredient than spray-dried forms. The crystallized mannitol produced maximal fine particle dose. The blends of the mannitols and the two active ingredients gave different results. The two techniques used to assess the adhesion of drugs to carrier particles provide complementary information about drug/carrier interactions and detachment. The mechanical sieving allows to assess blend stability and the air-jet sieving makes it possible to determine how easily the drug separates from carrier. For the drugs tested, the results of fine particle doses are in agreement with the Alpine air-jet sieve results. The tests used are helpful for the choice of a new carrier in the field of the development of new carriers for dry powder inhalers. PMID:17113733

Saint-Lorant, G; Leterme, P; Gayot, A; Flament, M P

2006-10-21

393

Synthesis of nanocrystalline tungsten carbide (WC) powder  

NASA Astrophysics Data System (ADS)

Nanocrystalline tungsten carbide (WC) has been obtained from bulk WO3 by in situ reduction and carbonization reactions at low temperature (~ 600 C) by taking Mg as reductant and acetone C3H6O as carbon source. It was aimed to elucidate carburization behavior of WO3 powder and to establish optimal conditions for the synthesis of nanocrystalline WC. The role of reaction time on the synthesis of WC has been investigated and discussed. The synthesized powders were characterized by X-ray powder diffraction, differential thermal analyzer (DTA), thermo gravimetric analysis (TGA).

Singla, Gourav; Singh, K.; Pandey, O. P.

2013-06-01

394

Electrical Resistivity of Metal Powder Aggregates  

NASA Astrophysics Data System (ADS)

An equation for calculating the electrical resistivity of a compressed powder mass, consisting of oxide-coated metal particles, has been derived. In addition to the intrinsic interest of the problem, the proposed equation is useful for describing the very early stages of electrical sintering processes. The problem is approached in a new way, relating the actual powder system to an equivalent system consisting of deforming spheres in a simple cubic packing, which is much easier to examine. The proposed equation was experimentally verified from measurements of the electrical resistivity for aluminum, bronze, iron, and nickel powders under pressure. The consistency between theoretical predictions and experimental results was reasonably good in all cases.

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

2007-12-01

395

Glass powder blended cement hydration modelling  

NASA Astrophysics Data System (ADS)

The use of waste materials in construction is among the most attractive options to consume these materials without affecting the environment. Glass is among these types of potential waste materials. In this research, waste glass in powder form, i.e. glass powder (GP) is examined for potential use in enhancing the characteristics of concrete on the basis that it is a pozzolanic material. The experimental and the theoretical components of the work are carried out primarily to prove that glass powder belongs to the "family" of the pozzolanic materials. The chemical and physical properties of the hydrated activated glass powder and the hydrated glass powder cement on the microstructure level have been studied experimentally and theoretically. The work presented in this thesis consists of two main phases. The first phase contains experimental investigations of the reaction of glass powder with calcium hydroxide (CH) and water. In addition, it includes experiments that are aimed at determining the consumption of water and CH with time. The reactivity, degree of hydration, and nature of the pore solution of the glass powder-blended cement pastes and the effect of adding different ratios of glass powder on cement hydration is also investigated. The experiments proved that glass powder has a pozzolanic effect on cement hydration; hence it enhances the chemical and physical properties of cement paste. Based on the experimental test results, it is recommended to use a glass powder-to-cement ratio (GP/C) of 10% as an optimum ratio to achieve the best hydration and best properties of the paste. Two different chemical formulas for the produced GP C-S-H gel due to the pure GP and GP-CH pozzolanic reaction hydration are proposed. For the pure GP hydration, the produced GP C-S-H gel has a calcium-to-silica ratio (C/S) of 0.164, water-to-silica ratio (H/S) of 1.3 and sodium/silica ratio (N/S) of 0.18. However, for the GP-CH hydration, the produced GP C-S-H gel has a C/S ratio of 1.17, H/S ratio of 2.5 and N/S ratio of 0.18. In the second phase of this research, theoretical models are built using a modified version of an existing cement hydration modelling code, "CEMHYD3D", to simulate the chemical reaction of the activated glass powder hydration and glass powder in cement. The modified model, which is referred to as the "MOD-model" is further used to predict the types, compositions and quantities of reaction products. Furthermore, the glass powder hydration data, which is obtained experimentally, is incorporated into the MOD-model to determine the effect of adding glass powder to the paste on the process of cement hydration and resulting paste properties. Comparisons between theoretical and experimental results are made to evaluate the developed models. The MOD-model predictions have been validated using the experimental results, and were further used to investigate various properties of the hydrated glass powder cement paste. These properties include, for example, CH content of the paste, porosity, hydration degree of the glass powder and conventional C-S-H and GP CS-H contents. The results show that the MOD-model is capable of accurately simulating the hydration process of glass powder-blended cement paste and can be used to predict various properties of the hydrating paste.

Saeed, Huda

396

Laminated composite of magnetic alloy powder and ceramic powder and process for making same  

DOEpatents

A laminated composite structure of alternating metal powder layers, and layers formed of an inorganic bonding media powder, and a method for manufacturing same are discosed. The method includes the steps of assembling in a cavity alternating layers of a metal powder and an inorganic bonding media of a ceramic, glass, and glass-ceramic. Heat, with or without pressure, is applied to the alternating layers until the particles of the metal powder are sintered together and bonded into the laminated composite structure by the layers of sintered inorganic bonding media to form a strong composite structure. The method finds particular application in the manufacture of high performance magnets wherein the metal powder is a magnetic alloy powder.

Moorhead, Arthur J. (Knoxville, TN); Kim, Hyoun-Ee (Seoul, KR)

1999-01-01

397

Improving aerosolization of drug powders by reducing powder intrinsic cohesion via a mechanical dry coating approach.  

PubMed

The aim of this study was to investigate the effect of coating on the aerosolization of three model micronized powders. Three model powder materials (salbutamol sulphate, salmeterol xinafoate, triamcinolone acetonide) were chosen not only for their different chemical properties but also for their different physical properties such as shape and size distribution. Each powder was coated with 5% (w/w) magnesium stearate using two different dry mechanofusion approaches. After mechanofusion, both poured and tapped densities for all three model drug powders significantly increased. There were significant improvements in aerosolization behavior from an inhaler device for all model powders after mechanofusion. Such improvements in aerosolization were attributed to the reduction in agglomerate strength caused by decreasing powder intrinsic cohesion via surface modification. The work also indicated that the effect of the coating was dependant on the initial particle properties. PMID:20435112

Zhou, Qi Tony; Qu, Li; Larson, Ian; Stewart, Peter J; Morton, David A V

2010-05-07

398

Laminated composite of magnetic alloy powder and ceramic powder and process for making same  

SciTech Connect

A laminated composite structure of alternating metal powder layers, and layers formed of an inorganic bonding media powder, and a method for manufacturing same are disclosed. The method includes the steps of assembling in a cavity alternating layers of a metal powder and an inorganic bonding media of a ceramic, glass, and glass-ceramic. Heat, with or without pressure, is applied to the alternating layers until the particles of the metal powder are sintered together and bonded into the laminated composite structure by the layers of sintered inorganic bonding media to form a strong composite structure. The method finds particular application in the manufacture of high performance magnets wherein the metal powder is a magnetic alloy powder. 9 figs.

Moorhead, A.J.; Kim, H.

1999-08-10

399

Shock consolidation of powders: theory and experiment  

SciTech Connect

A recently proposed model of shock consolidation of powders quantitatively predicts regimes of input energy and shock duration required to produce well-bonded compacts. A growing data base from shock experiments in which the shock wave and powder parameters of importance are controlled allows evaluation of the model. Rapidly solidified crystalline AISI 9310, and microcrystalline Markomet 3.11, as well as amorphous Markomet 1064 and crystalline Mo powders, have been consolidated by shocks up to 2 ..mu..s duration. The formation of amorphous layers on Marko 3.11 particle surfaces indicates that surface melting and rapid solidification occurred. Decreasing amounts of amorphous structure are retained in Marko 3.11 and 1064 powder compacts with increasing shock energies. Significant improvement in Mo particle bonding is achieved by reducing surface oxides prior to shock consolidation.

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

1984-01-01

400

High charge, low leakage tantalum powders  

SciTech Connect

Tantalum powders for electrolytic capacitors having improved electrical capacity and low direct current leakage characteristics are produced by the introduction of combinations of carbon, nitrogen and sulfur-containing materials.

Schiele, E. K.; Manley Jr., R. V.; Rerat, C. F.

1985-10-01

401

The technologies of titanium powder metallurgy  

Microsoft Academic Search

Titanium alloys exhibit attractive mechanical properties but they are expensive. This paper reviews the current status of\\u000a titanium powder metallurgy which offers near-net shape cost-effective approaches to the fabrication of components.

F. H. Froes; S. J. Mashl; J. C. Hebeisen; V. S. Moxson; V. A. Duz

2004-01-01

402

30 CFR 57.6901 - Black powder.  

Code of Federal Regulations, 2013 CFR

... SAFETY AND HEALTH STANDARDS-UNDERGROUND METAL AND NONMETAL MINES Explosives...General Requirements-Surface and Underground § 57.6901 Black powder...open flame; (ii) Within any building in which a fuel-fired or...

2013-07-01

403

A qualitative comparison of smokeless powder measurements.  

PubMed

In the spring of 2000, the National Institute of Standards and Technology and nineteen participants conducted a comparison of smokeless powder additive compositional measurements. The purpose of this exercise was to determine the state-of-the-practice for forensic smokeless powder determinations. For the comparison, two handgun reloading powder samples were mixed and were compositionally evaluated for homogeneity by NIST. Participant laboratories included military, academic, and state/local, federal, and international forensic agencies. We solicited qualitative data identifying nitroglycerin, diphenylamine, N-nitrosodiphenylamine, and ethyl centralite. In addition, some laboratories provided identification of additional ingredients, such as nitrocellulose, or reported other measurements, such as dimensional morphology. In this paper, laboratory identification of the smokeless powder additives and a summary of the measurement methods used for the evaluations are presented. All laboratories correctly identified NG and the major stabilizers. Some disparity between laboratories was noted for the identification of minor (<0.01% by weight) stabilizers and stabilizer decomposition products. PMID:12353587

MacCrehan, William A; Reardon, Michelle R

2002-09-01

404

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

405

The technologies of titanium powder metallurgy  

NASA Astrophysics Data System (ADS)

Titanium alloys exhibit attractive mechanical properties but they are expensive. This paper reviews the current status of titanium powder metallurgy which offers near-net shape cost-effective approaches to the fabrication of components.

Froes, F. H.; Mashl, S. J.; Hebeisen, J. C.; Moxson, V. S.; Duz, V. A.

2004-11-01

406

Characteristics and pozzolanic reactivity of glass powders  

Microsoft Academic Search

This paper deals with the morphology, fineness and pozzolanic activity of four glass powders: one (GP-fine) from the screening of crushed waste glasses, one (GP-dust) from a dust collector for the glass crushing process and two (GP-4000 and GP-6000) from further grinding of the powder from the dust collector in a ball mill. GP-fine and GP-dust consist mainly of large

Caijun Shi; Yanzhong Wu; Chris Riefler; Hugh Wang

2005-01-01

407

Fabrication of microstructures by powder blasting  

Microsoft Academic Search

This thesis deals with the use of powder blasting as a micromachining\\u000atechnique to create micro systems. Powder blasting is a technology in\\u000awhich small particles, accelerated by an air jet, are directed towards a\\u000abrittle target for mechanical material removal. It is especially useful for\\u000aglass machining due to the limitations of other glass micromachining\\u000atechniques.\\u000aParticle jets have

Hendrik Wensink

2002-01-01

408

Turbulent electrical transport in copper powders  

Microsoft Academic Search

Compressed copper powder has a very large electrical resistance (1 M?), due to the oxide layer on grains (100 ?m). We observe that its voltage-current U-I characteristics are nonlinear, and undergo an instability, from an insulating to a conductive state at relatively small applied voltages. Current through the powder is then noisy, and the noise has interesting self-similar properties, including

Eric Falcon; Bernard Castaing; Claude Laroche

2004-01-01

409

Oxidation behaviour of boron carbide powder  

Microsoft Academic Search

Isothermal oxidation behaviour of powdered boron carbide (B4C) with the fine (1.52?m), medium (22.5?m) and coarse (59.6?m) particle size has been studied in air ranging from 500 to 800C. The oxidation rate strongly depends on the particle size of boron carbide and temperature. The smaller particle size the higher oxidation rate of B4C powder due to its larger surface area.

Y. Q. Li; T. Qiu

2007-01-01

410

Relative flow rates of explosive powders  

SciTech Connect

A study was performed to determine the relative flow rates of various explosive powders and evaluate their adaptability for use in automated dispensing systems. Results showed that PBX 9407, LX-15, RX-26-BH, and HNAB are potential candidates for use in these systems. It was also shown that powders with graphite and stearate additives generated the least amount of static and were the easiest to handle.

Willson, V.P.

1988-05-31

411

Electrical Resistivity of Metal Powder Aggregates  

Microsoft Academic Search

An equation for calculating the electrical resistivity of a compressed powder mass, consisting of oxide-coated metal particles,\\u000a has been derived. In addition to the intrinsic interest of the problem, the proposed equation is useful for describing the\\u000a very early stages of electrical sintering processes. The problem is approached in a new way, relating the actual powder system\\u000a to an equivalent

J. M. Montes; F. G. Cuevas; J. Cintas

2007-01-01

412

Drying powders for crucibles of induction furnaces  

Microsoft Academic Search

UDC 666.762.2.047.75 Powders used for ramming the crucibles of induction furnaces in the melting of iron at automobile factories are prepared from quartzites from the Karaul mountains. The properties of the powders are: weight proportion of SiO 2 not less than 97.5%, A1203 not more than 1.3%, Fe203 not more than 0.6%, refractoriness not less than 1730~ and moisture content

I. P. Tsibin; M. Z. Shvartsman; G. V. Orlov; M. Z. Naginskii; E. M. Grishpun

1980-01-01

413

Moisture sorption of Thai red curry powder  

Microsoft Academic Search

Moisture sorption study was conducted on Thai red curry powder prepared by two different drying methods, viz. microwave and hot-air drying. Moisture sorption isotherms of the red curry powder at 30 ?C and water activity in the range of 0.113-0.970 were determined by a static gravimetric method. The isotherms exhibited Type III behaviour. The moisture sorption data were fitted to

Sudathip Inchuen; Woatthichai Narkrugsa; Pimpen Pornchaloempong

414

Electrical resistivity of a titanium powder mass  

Microsoft Academic Search

In this paper, the variation with the porosity of the electrical resistivity of a compressed powder mass of commercially pure\\u000a titanium has been studied. The study has been carried out via the direct measurement of the electrical resistance of a powder\\u000a column subjected to uniaxial compression. The obtained experimental data have been fit to a theoretical model, proposed by\\u000a the

J. M. Montes; F. G. Cuevas; J. Cintas

2011-01-01

415

Electrical conductivity of metal powders under pressure  

Microsoft Academic Search

A model for calculating the electrical conductivity of a compressed powder mass consisting of oxide-coated metal particles\\u000a has been derived. A theoretical tool previously developed by the authors, the so-called equivalent simple cubic system,\\u000a was used in the model deduction. This tool is based on relating the actual powder system to an equivalent one consisting of\\u000a deforming spheres packed in

J. M. Montes; F. G. Cuevas; J. Cintas; P. Urban

416

Research of minimum ignition energy for nano Titanium powder and nano Iron powder  

Microsoft Academic Search

Most manufacturing units that process nanoparticles face a threat from fires and explosions. This study examines Ti powders with diameters of 3?m, 8?m, 20?m, 45?m, 35nm, 75nm, and 100nm, and Fe powders with diameters of 150?m, 15nm, 35nm, and 65nm. The goal of our study was to measure the minimum ignition energy (MIE) for each of the above mentioned powders

Hong-Chun Wu; Ri-Cheng Chang; Hsiao-Chi Hsiao

2009-01-01

417

A novel standard sample powder preparation method for quantitative analysis of polymorphs.  

PubMed

The purpose of this study was to improve the sensitivity and accuracy of the quantitative analysis of polymorphic mixtures. Calibration curve reliability has been improved through the advancement of standard mixture preparation techniques whereby samples at scales of several grams are homogeneously and accurately prepared without decrease in crystallinity. Crystalline powders are first micronized to anisotropic, nearly equal-sized (<10 microm) particles of almost random orientation in an air jet mill. These powders are then mixed in a vibration mill that includes rubber balls as mixing media. Using this technique, alpha and gamma forms of indomethacin (IMC) were prepared in various proportions from 0.5% to 50% alpha content and subjected to X-ray powder diffraction analysis. The validation data showed that these precisely prepared standard mixtures resulted in superior analytical sensitivity and accuracy compared to those prepared by agate mortar. PMID:15793799

Okumura, Takehiro; Otsuka, Makoto

2005-05-01

418

Investigation of pressing and sintering processes of CP-Ti powder made by Armstrong Process  

SciTech Connect

This work used in-situ and ex-situ techniques to investigate the pressing and sintering processes of commercially pure (CP) Titanium (Ti) powder made by the Armstrong process. The objective is to simulate the actual manufacturing process of near net shape Ti components. Ti powders were uniaxially pre-pressed at designated pressures up to 100 ksi to form disk samples with different theoretical densities. Compression tests were performed in an SEM at different temperatures to obtain the mechanical properties and deformation behavior of these samples. Ex-situ technique was used to track the powder deformation process of disk samples from low pressure to high pressure. In-situ sintering was also performed in an SEM to record the morphology change of the porosities on the sample surface during the sintering process. The results will provide valuable information for optimizing the manufacturing process of high-density near net shape Ti components.

Chen, Wei [Michigan State University, East Lansing; Yamamoto, Yukinori [ORNL; Peter, William H [ORNL

2010-01-01

419

Fuel powder production from ductile uranium alloys.  

SciTech Connect

Metallic uranium alloys are candidate materials for use as the fuel phase in very-high-density LEU dispersion fuels. These ductile alloys cannot be converted to powder form by the processes routinely used for oxides or intermetallics. Three methods of powder production from uranium alloys have been investigated within the US-RERTR program. These processes are grinding, cryogenic milling, and hydride-dehydride. In addition, a gas atomization process was investigated using gold as a surrogate for uranium. Grinding was found to be inefficient and introduced impurities into the fuel. Cryogenic milling of machine chips in a steel vial was found to have similar shortcomings. The hydride-dehydride process has historically been used to produce very fine powder that may not be suitable for fuel fabrication. Uranium is made to form its hydride by heating in a hydrogen atmosphere. Subsequent heating under vacuum drives off hydrogen gas and returns the hydride to a metallic state. The volume change on hydride formation results in a fine powder upon dehydriding. The effects of alloying elements, partial hydriding, and subsequent milling treatments on particle size distribution are being explored. Inert gas atomization is used on an industrial scale to produce metal powder. Current designs are not suitable for use with uranium. A system was specifically designed for uranium atomization. A prototype was built and tested using gold as a surrogate for uranium. The system operates efficiently and can produce powder in a variety of size ranges by changing the atomization nozzle.

Clark, C. R.

1998-10-23

420

Electrical conductivity of metal powders under pressure  

NASA Astrophysics Data System (ADS)

A model for calculating the electrical conductivity of a compressed powder mass consisting of oxide-coated metal particles has been derived. A theoretical tool previously developed by the authors, the so-called `equivalent simple cubic system', was used in the model deduction. This tool is based on relating the actual powder system to an equivalent one consisting of deforming spheres packed in a simple cubic lattice, which is much easier to examine. The proposed model relates the effective electrical conductivity of the powder mass under compression to its level of porosity. Other physically measurable parameters in the model are the conductivities of the metal and oxide constituting the powder particles, their radii, the mean thickness of the oxide layer and the tap porosity of the powder. Two additional parameters controlling the effect of the descaling of the particle oxide layer were empirically introduced. The proposed model was experimentally verified by measurements of the electrical conductivity of aluminium, bronze, iron, nickel and titanium powders under pressure. The consistency between theoretical predictions and experimental results was reasonably good in all cases.

Montes, J. M.; Cuevas, F. G.; Cintas, J.; Urban, P.

2011-12-01

421

Characterizing titanium powder: morphology, flow and segregation  

NASA Astrophysics Data System (ADS)

Powder metallurgy manufacturing with titanium could achieve near-net shape for parts with high strength-to-weight ratio. However, pure titanium (Ti) powders have large aspect ratios that prevent smooth flow. Features of Ti powder were examined experimentally to understand its limited flowability. The surface morphology was measured using a SEM for both raw powder as well as those made ``uniform'' via milling. The poly-disperse mixture had particle sizes between 45--700 ?m, of which a significant concentration were <45?m, which results in a very steep and unsteady angle of repose when the powder was placed in a rotating tumbler. The flat surface and steady flow typical of macroscopic particles is not present, but instead has slumping motion as material piles up and collapses intermittently. Spectral analysis indicates that increasing Froude number causes the slumping behavior to move to higher frequencies, but spread over a larger range. Size segregation causes porous streaks to form at the periphery of the tumbler where the angular separation of the streaks decreases with increasing Froude number. The overall conclusion is that more narrow ranges of particle size are necessary to yield usable titanium in powder metallurgy manufacturing.

Pohlman, Nicholas A.; Roberts, John A.; Gonser, Matthew

2011-11-01

422

Powder diffraction studies using anomalous dispersion  

SciTech Connect

With the increasing availability and accessibility of high resolution powder diffractometers at many synchrotron radiation sources throughout the world, there is rapidly-growing interest in the exploitation of anomalous dispersion techniques for structural studies of polycrystalline materials. In conjunction with the Rietveld profile method for structure refinement, such studies are especially useful for the determination of the site distributions of two or more atoms which are near neighbors in the periodic table, or atoms which are distributed among partially occupied sites. Additionally, it is possible to (1) determine the mean-square displacements associated with different kinds of atoms distributed over a single set of sites, (2) distinguish between different oxidation states and coordination geometries of a particular atom in a compound and (3) to determine f' for a wide range of atomic species as a function of energy in the vicinity of an absorption edge. Experimental methods for making anomalous dispersion measurements are described in some detail, including data collection strategies, data analysis and correlation problems, possible systematic errors, and the accuracy of the results. Recent work in the field is reviewed, including cation site-distribution studies (e.g. doped high [Tc] superconductors, ternary alloys, FeCo[sub 2](PO[sub 4])[sub 3], FeNi[sub 2]BO[sub 5]), oxidation-state contrast (e.g. YBa[sub 2]Cu[sub 3]O[sub 6+x], Eu[sub 3]O[sub 4], GaCl[sub 2], Fe[sub 2]PO[sub 5]), and the effect of coordination geometry (e.g. Y[sub 3]Ga[sub 5]O[sub l2]).

Cox, D.E. (Brookhaven National Lab., Upton, NY (United States)); Wilkinson, A.P. (California Univ., Santa Barbara, CA (United States). Dept. of Materials)

1993-01-01

423

Growth and characterization of L-histidine cadmium chloride monohydrate a semiorganic nonlinear optical crystals  

NASA Astrophysics Data System (ADS)

L-histidine cadmium chloride monohydrate (LHCCM), a semiorganic nonlinear optical material was grown from aqueous solution by slow solvent evaporation method at room temperature. The LHCCM crystals were characterized by X-ray powder diffraction analysis. The presence of functional groups was identified through fourier transform infrared spectroscopy. Thermogravimetric and differential thermal analysis confirms that the crystal is stable up to 277 C. The dielectric constant was studied as a function of frequency for various temperatures. The mechanical properties of the grown crystals have been studied using Vickers microhardness tester. The second harmonic generation behavior of LHCCM crystal was tested by modified Kurtz-Perry powder technique.

Chandrasekaran, J.; Ilayabarathi, P.; Maadeswaran, P.; Mohamed Kutty, P.; Pari, S.

2012-04-01

424

Synthesis of ?- and ?-Rhombohedral Boron Powders via Gas Phase Thermal Dissociation of Boron Trichloride by Hydrogen  

NASA Astrophysics Data System (ADS)

The ?-rhombohedral and ?-rhombohedral crystal structures of pure elemental boron powders have been synthesized via gas phase thermal dissociation of BCl3 by H2 on a quartz substrate. The parameters affecting the crystal structures of the final products and the process efficiency, such as BCl3/H2 molar ratio (1/2 and 1/4) and reaction temperature (1173 K to 1373 K [900 C to 1100 C]), have been examined. The experimental apparatus of original design has enabled boron powders to be obtained at temperatures lower than those in the literature. The surface/powder separation problem encountered previously with different substrate materials has been avoided. Boron powders have been synthesized with a minimum purity of 99.99 pct after repeated HF leaching. The qualitative analysis of exhaust gases has been conducted using a Fourier transform infrared spectroscope (FTIR). The synthesized powders have been characterized using an X-ray powder diffractometer (XRD) and scanning electron microscope (SEM) techniques. The results of the reactions have been compared with equilibrium predictions performed using the FactSage 6.2 (Center for Research in Computational Thermochemistry, Montreal, Canada) thermochemical software.

A?ao?ullar?, Duygu; Balc?, zge; Duman, Ismail; veo?lu, M. Ltfi

2011-06-01

425

Laser-induced breakdown spectroscopy measurements of uranium and thorium powders and uranium ore  

NASA Astrophysics Data System (ADS)

Laser-induced breakdown spectroscopy (LIBS) was used to analyze depleted uranium and thorium oxide powders and uranium ore as a potential rapid in situ analysis technique in nuclear production facilities, environmental sampling, and in-field forensic applications. Material such as pressed pellets and metals, has been extensively studied using LIBS due to the high density of the material and more stable laser-induced plasma formation. Powders, on the other hand, are difficult to analyze using LIBS since ejection and removal of the powder occur in the laser interaction region. The capability of analyzing powders is important in allowing for rapid analysis of suspicious materials, environmental samples, or trace contamination on surfaces since it most closely represents field samples (soil, small particles, debris etc.). The rapid, in situ analysis of samples, including nuclear materials, also reduces costs in sample collection, transportation, sample preparation, and analysis time. Here we demonstrate the detection of actinides in oxide powders and within a uranium ore sample as both pressed pellets and powders on carbon adhesive discs for spectral comparison. The acquired LIBS spectra for both forms of the samples differ in overall intensity but yield a similar distribution of atomic emission spectral lines.

Judge, Elizabeth J.; Barefield, James E., II; Berg, John M.; Clegg, Samuel M.; Havrilla, George J.; Montoya, Velma M.; Le, Loan A.; Lopez, Leon N.

2013-05-01

426

The filling of powdered herbs into two-piece hard capsules using hydrogenated cotton seed oil as lubricant.  

PubMed

The aim of this work was to investigate the plug formation and filling properties of powdered herbal leaves using hydrogenated cotton seed oil as an alternative lubricant. In a first step, unlubricated and lubricated herbal powders were studied on a small scale using a plug simulator, and low-force compression physics and parameterization techniques were used to narrow down the range in which the optimum amount of lubricant required would be found. In a second step these results were complemented with investigations into the flow properties of the powders based on packing (tapping) experiments to establish the final optimum lubricant concentration. Finally, capsule filling of the optimum formulations was undertaken using an instrumented tamp filling machine. This work has shown that hydrogenated cotton seed oil can be used advantageously for the lubrication of herbal leaf powders. Stickiness as observed with magnesium stearate did not occur, and the optimum lubricant concentration was found to be less than that required for magnesium stearate. In this work, lubricant concentrations of 1% or less hydrogenated cotton seed oil were required to fill herbal powders into capsules on the instrumented tamp-filling machine. It was found that in principle all powders could be filled successfully, but that for some powders the use of higher compression settings was disadvantageous. Relationships between the particle size distributions of the powders, their flow and consolidation as well as their filling properties could be identified by multivariate statistical analysis. The work has demonstrated that a combination of the identification of plug formation and powder flow properties is helpful in establishing the optimum lubricant concentration required using a small quantity of powder and a powder plug simulator. On an automated tamp-filling machine, these optimum formulations produced satisfactory capsules in terms of coefficient of fill weight variability and capsule weight. PMID:22960627

Aling, Joanna; Podczeck, Fridrun

2012-08-31

427

Chemical vapor deposited diamond-on-diamond powder composites (LDRD final report)  

SciTech Connect

Densifying non-mined diamond powder precursors with diamond produced by chemical vapor infiltration (CVI) is an attractive approach for forming thick diamond deposits that avoids many potential manufacturability problems associated with predominantly chemical vapor deposition (CVD) processes. The authors developed techniques for forming diamond powder precursors and densified these precursors in a hot filament-assisted reactor and a microwave plasma-assisted reactor. Densification conditions were varied following a fractional factorial statistical design. A number of conclusions can be drawn as a result of this study. High density diamond powder green bodies that contain a mixture of particle sizes solidify more readily than more porous diamond powder green bodies with narrow distributions of particle sizes. No composite was completely densified although all of the deposits were densified to some degree. The hot filament-assisted reactor deposited more material below the exterior surface, in the interior of the powder deposits; in contrast, the microwave-assisted reactor tended to deposit a CVD diamond skin over the top of the powder precursors which inhibited vapor phase diamond growth in the interior of the powder deposits. There were subtle variations in diamond quality as a function of the CVI process parameters. Diamond and glassy carbon tended to form at the exterior surface of the composites directly exposed to either the hot filament or the microwave plasma. However, in the interior, e.g. the powder/substrate interface, diamond plus diamond-like-carbon formed. All of the diamond composites produced were grey and relatively opaque because they contained flawed diamond, diamond-like-carbon and glassy carbon. A large amount of flawed and non-diamond material could be removed by post-CVI oxygen heat treatments. Heat treatments in oxygen changed the color of the composites to white.

Panitz, J.K.; Hsu, W.L.; Tallant, D.R.; McMaster, M.; Fox, C.; Staley, D.

1995-12-01

428

Effect of powder loading on metal injection molding stainless steels  

Microsoft Academic Search

Powder loading is one of the most critical factors which has important influence on metal injection molding processes. Using the gas atomized spherical 17-4 PH stainless steel powder and the binder of 65% PW+30% EVA+5% SA, four kinds of feedstocks were prepared at the powder loading of 60, 64, 68 and 72%, respectively. The effects of the powder loading on

Yimin Li; Liujun Li; K. A. Khalil

2007-01-01

429

Sintering characteristics of highly active UO2 powder  

Microsoft Academic Search

A highly active UO powder of 5 to 15m²\\/g specific surface area can be obtained by a conversion process we have developed. This powder can be sintered to high density at a lower temperature than conventional powder; thus, the sintering temperature can be lowered in the manufacturing plant. In this study, sintering characteristics of the active powder, such as correlation

Wataru Saiki; Takeshi Onoue; Shinichi Hasegawa

1995-01-01

430

Calcining influence on the powder properties of hydroxyapatite  

Microsoft Academic Search

The effect of different calcination temperatures on the powder characteristics and the sintered density of synthetic hydroxyapatite (HA) powders, produced using two different processing routes, was examined. Powders were produced by either drying, milling and sieving an as-precipitated HA or by spray-drying a slurry of precipitated HA. Calcining the two powders at temperatures between 400 and 1000 C did not

N. Patel; I. R. Gibson; S. Ke; S. M. Best; W. Bonfield

2001-01-01

431

Determination of the adsorptive capacity and adsorption isotherm of vapor-phase mercury chloride on powdered activated carbon using thermogravimetric analysis  

Microsoft Academic Search

This study investigated the use of thermogravimetric analysis (TGA) to determine the adsorptive capacity and adsorption isotherm of vapor-phase mercury chloride on powdered activated carbon (PAC). The technique is commonly applied to remove mercury-containing air pollutants from gas streams emitted from municipal solid waste incinerators. An alternative form of powdered activated carbon derived from a pyrolyzed tire char was prepared

Hsun-Yu Lin; Chung-Shin Yuan; Wei-Ching Chen; Chung-Hsuang Hung

2006-01-01

432

Combining wire and coaxial powder feeding in laser direct metal deposition for rapid prototyping  

NASA Astrophysics Data System (ADS)

Powder and wire deposition have been used separately in many laser-cladding, rapid prototyping and other additive manufacturing applications. In this paper, a new approach is investigated by simultaneously feeding powder from a coaxial nozzle and wire from an off-axis nozzle into the deposition melt pool. Multilayer parts are built from 316L steel using a 1.5 kW diode laser and different configurations of the powder and wire nozzles are compared in terms of surface roughness, deposition rate, porosity and microstructure. The parts are analysed using scanning electron microscopy (SEM), X-ray diffraction (XRD) and optical microscopy techniques. Results show that deposition efficiency increased and surface roughness decreased with the combined process; some porosity was present in samples produced by this method, but it was 20 30% less than in samples produced by powder alone. Wire injection angles into the melt pool in both horizontal and vertical planes were found to be significant for attaining high deposition efficiency and good surface quality. Reasons for the final sample characteristics and differences between the combined process and the separate powder and wire feeding techniques are discussed.

Syed, Waheed Ul Haq; Pinkerton, Andrew J.; Li, Lin

2006-04-01

433

Determination of trace impurities in powdered molybdenum metal and molybdenum silicide by solid sampling GFAAS  

Microsoft Academic Search

A direct atomic absorption spectrometric method for the determination of the elements Cu, K, Mg, Mn, Na and Zn in high purity molybdenum metal and molybdenum silicide powders for microelectronic applications was developed. By using a cup and boat solid sampling technique, the sample preparation step and the contamination risk were considerably reduced, so that these elements could be determined

Bohumil Docekal; Viliam Krivan

1995-01-01

434

Britz-Heidbrink Inc. Mini-CRADA, Powder Coating of Animal Enclosures.  

National Technical Information Service (NTIS)

The goal of this CRADA was to combine the powder coating material and application techniques and laboratory testing capabilities of FM and T with the manufacturing, real-world testing, and practical knowledge available to BHI in a limited study to determi...

M. D. Smith

2000-01-01

435

Thermal and mechanical properties of copper powder filled poly (ethylene) composites  

Microsoft Academic Search

The thermal conductivity and mechanical properties such as tensile strength, elongation at break, modulus of elasticity, and toughness of composites formed by copper powder filler embedded in a high density poly(ethylene) matrix are investigated experimentally and the results compared with existing theories. Thermal conductivity measurements are performed up to a filler concentration of 10 vol.%. A modified hotwire technique is

I. H. Tavman

1997-01-01

436

Copper-tungsten composite powders by the hydrogen reduction of copper tungstate  

Microsoft Academic Search

The reduction of two different samples of copper tungstate at 500, 600 and 700 C has been studied using thermogravimetry, X-ray diffraction analysis and electron optical techniques. The morphologies of the resultant Cu-W powders have been related to the morphologies of the original tungstate samples and to the time and temperatures of reduction. The reduction mechanism of the tungstate has

A. K. Basu; F. R. Sale

1978-01-01

437

Development of a Tabletop Model for the Generation of Amorphous/Microcrystalline Metal Powders.  

National Technical Information Service (NTIS)

Electrohydrodynamics (EHD) was used as a basis for the generation and control of charged liquid droplets in order to produce micro-size powders and splat coatings. The EHD technique requires the use of intense electric fields to generate liquid droplets d...

B. E. Kalensher J. Perel J. F. Mahoney S. Taylor Z. Shanfield

1982-01-01

438

Structural changes induced by the mechanical alloying of crystalline metal powders  

Microsoft Academic Search

The authors report structural results of mechanical alloying binary mixtures of pure elemental powders as a function of milling time. X-ray line broadening techniques are used to follow the lattice destabilization caused by interdiffusion of elements, which is favoured by a negative heat of mixing. Experimental evidence is outlined on the formation of highly distorted solid solutions and intermetallic compounds,

S. Enzo; E. Bonetti; I. Soletta; G. Cocco

1991-01-01

439

Dynamic powder compaction of rapidly solidified Path A alloy with increased carbon and titanium content  

SciTech Connect

The objective of this study is to show the potential of the dynamic powder compaction technique to consolidate rapidly solidified Path A alloys and to develop microstructures with improved irradiation performance in the fusion environment. Samples of rapidly solidified and dynamically compacted Path A alloy with increased carbon and titanium content have been included in alloy development irradiation experiments.

Megusar, J.; Imeson, D.; Vander Sande, J.B.; Grant, N.J.

1982-01-01

440

TEM observations on the microstructure of an atomized high-purity aluminium powder  

Microsoft Academic Search

Rapid solidification techniques have emerged as useful means for producing metal alloys that exhibit improved properties compared with conventionally processed materials. The property improvements are usually attributed to such factors as improved homogeneity, refined microstructures and extended solubility, which originate from the initial structure of the powders. Of particular concern during fabrication is the ability to retain the rapid solidification

B. H. Rabin; R. N. Wright; J. E. Flinn; J. B. Adams

1989-01-01

441

Water Outgassing from PBX-9502 powder by isoconversional thermal analysis  

SciTech Connect

Temperature programmed desorption/decomposition (TPD) were performed on PBX-9502 after 3 hours of vacuum pump. TPD data were analyzed by the technique of isoconversional analysis to obtain outgassing kinetics and moisture content of PBX-9502 powder as well as to construct water outgassing models for PBX-9502 powder as a function of time and temperature. Following 3 hours of vacuum pump, dry storage of PBX-9502 at 300K, quickly gives rise to 180-330 ppm moisture in the first few years. Thereafter, the moisture outgassing continues at a much slower rate, totaling only to {approx} 210-380 ppm after 100 years of storage. In an effort to understand the nature of the moisture outgassing in PBX-9502, we have measured moisture content and outgassing kinetics in PBX-9502 by the experimental technique of TPD and the isoconversional thermal analysis. The results of these measurements were then used to construct moisture outgassing models for PBX-9502 in a dry environment (following 3 hours of vacuum pump).

Dinh, L N; Glascoe, E L; Small, W

2009-01-12

442

GRADIENT INDEX SPHERES BY THE SEQUENTIAL ACCRETION OF GLASS POWDERS  

SciTech Connect

The Department of Energy is seeking a method for fabricating mm-scale spheres having a refractive index that varies smoothly and continuously from the center to its surface [1]. The fabrication procedure must allow the creation of a range of index profiles. The spheres are to be optically transparent and have a refractive index differential greater than 0.2. The sphere materials can be either organic or inorganic and the fabrication technique must be capable of scaling to low cost production. Mo-Sci Corporation proposed to develop optical quality gradient refractive index (GRIN) glass spheres of millimeter scale (1 to 2 mm diameter) by the sequential accretion and consolidation of glass powders. Other techniques were also tested to make GRIN spheres as the powder-accretion method produced non-concentric layers and poor optical quality glass spheres. Potential ways to make the GRIN spheres were (1) by "coating" glass spheres (1 to 2 mm diameter) with molten glass in a two step process; and (2) by coating glass spheres with polymer layers.

MARIANO VELEZ

2008-06-15

443

Analysis of anisotropy produced by packed-rolling in rapidly-quenched Nd-Fe-B powder  

SciTech Connect

The authors have applied a multi-pass packed-rolling technique to the production of anisotropic Nd-Fe-B-Cu powders from rapidly quenched ribbons. Analysis of the packed-rolling process shows that densification proceeds from the surface of the packed powder-compact and crystallographic alignment proceeds more rapidly at the center. Rolling to a reduction in ribbon thickness of greater than 80% results in a uniform material with a high (BH)[sub max] of up to 38 MGOe. The present paper discusses the alignment mechanism, taking into consideration the internal stress distribution inside the powder compact under rolling pressure.

Sakamoto, H.; Mukai, T.

1993-01-01

444

Vacuum hot pressing of titanium-alloy powders  

Microsoft Academic Search

Full or nearly full dense products of wrought-metal properties have been obtained by vacuum hot pressing (VHP) of several prealloyed Ti--6Al--4V powders including hydride, hydride\\/dehydride, and rotating electrode process (REP) spherical powder. The properties of billets VHP from Ti--6Al--4V hydride powder and from hydride\\/dehydride powders have been shown to be equivalent. The REP spherical powder billets processed by VHP or

Malik

1975-01-01

445

Rheological and Thermal Debinding Behaviors in Titanium Powder Injection Molding  

Microsoft Academic Search

Powder injection molding (PIM) is suitable for the fabrication of complex shape titanium and its alloys and has a great potential\\u000a in many applications. This article deals with the injection molding of hydride-dehydride (HDH) titanium powder, spheroidized\\u000a HDH titanium powder, and gas-atomized (GA) titanium powder. Rheological and thermal debinding behaviors are compared between\\u000a feedstocks made from the three powders. Torque

Seong-Jin Park; Yunxin Wu; Donald F. Heaney; Xin Zou; Guosheng Gai; Randall M. German

2009-01-01

446

NiAl powder alloys: II. Compacting of NiAl powders produced by various methods  

NASA Astrophysics Data System (ADS)

The technological properties of granulated NiAl powders produced by gas spraying of melts and NiAl powders produced by calcium hydride reduction (CHR) of mixtures of nickel and aluminum oxides are compared. The possibilities of production of compact workpieces from these powders using hydrostatic pressing, hot pressing, hot isostatic pressing, and hot extrusion are estimated. To improve compressibility, preliminary milling and/or mechanical activation of the powders are proposed. The strength properties of NiAl rods with a diameter of 20 mm extruded from a temperature of 1100C and made from the granulated powders are slightly higher than those made from the CHR powders. At temperatures higher than 800C the properties becomes similar. Transition point t d.b from the ductile to brittle state of samples made from powders sprayed in nitrogen and argon is 100-150C higher than those made from the CHR powders. The difference in the mechanical properties is caused by the structural and chemical microheterogeneity of granules (microingots), which is inherited in the rods after hot deformation and annealing at 1200-1400C and is (0.67-0.88) T m NiAl ( T m is the melting point, K).

Skachkov, O. A.; Povarova, K. B.; Drozdov, A. A.; Morozov, A. E.

2012-05-01

447

Preparation of pure perovskite-type BaSnO 3 powders by the polymerized complex method at reduced temperature  

Microsoft Academic Search

Cubic perovskite-type pure barium stannate, BaSnO3, powders were prepared using the polymerized complex technique at the relatively low temperature of 600C. SnCl4xH2O was first dissolved in ethylene glycol (EG) and anhydrous citric acid (CA) was then added. After complete dissolution, BaCO3 powder was added and the mixture was stirred at 80C for several hours until the solution became transparent, demonstrating

Chandana Premakumara Udawatte; Masato Kakihana; Masahiro Yoshimura

1998-01-01

448

One-step synthesis of barium hexaferrite nano-powders via microwave-assisted solgel auto-combustion  

Microsoft Academic Search

Single phase barium hexaferrite nano-powders have been innovatively one-step synthesized via a microwave-assisted solgel auto-combustion in a specially designed quartz vessel using citric acid and ethylene diamine tetraacetic acid as composite chelating agents and freeze-drying technique to remove sols moisture. The auto-combustion product powder is characterized by fluffy particle aggregates with the crystallites ranging from 50 to 100nm in diameter

Liu Junliang; Zeng Yanwei; Guo Cuijing; Zhang Wei; Yang Xiaowei

2010-01-01

449

Dry polymer powder coating and comparison with conventional liquid-based coatings for Eudragit RS, ethylcellulose and shellac  

Microsoft Academic Search

Drug-layered pellets were coated with micronized polymer powders (Eudragit RS, ethylcellulose, and shellac) by a dry powder coating technique as an alternative to organic- and aqueous-based coatings (Eudragit RS 30D, Aquacoat ECD) were investigated. High plasticizer concentrations (40%) and a thermal after-treatment (curing) were necessary for the coalescence of the polymer particles and good film formation. Ethylcellulose required a higher

Nantharat Pearnchob; Roland Bodmeier

2003-01-01

450

Effect of Calcination Condition on Phase Formation of Zirconium Titanate Powders Synthesized by the Solid-State Reaction  

Microsoft Academic Search

Zirconium titanate (ZrTiO4; ZT) powders have been prepared by using a solid-state reaction combined with a vibro-milling technique. The effects of calcination temperature, dwell time and heating\\/cooling rates on phase formation and morphology of the powders were examined. The calcination temperature and dwell time have been found to show a pronounced effect on the phase formation of the calcined zirconium

Anurak Prasatkhetragarn; Rattikorn Yimnirun; Supon Ananta

2007-01-01

451

Die-target for dynamic powder consolidation  

DOEpatents

A die/target is disclosed for consolidation of a powder, especially an atomized rapidly solidified metal powder, to produce monoliths by the dynamic action of a shock wave, especially a shock wave produced by the detonation of an explosive charge. The die/target comprises a rectangular metal block having a square primary surface with four rectangular mold cavities formed therein to receive the powder. The cavities are located away from the geometrical center of the primary surface and are distributed around such center while also being located away from the geometrical diagonals of the primary surface to reduce the action of reflected waves so as to avoid tensile cracking of the monoliths. The primary surface is covered by a powder retention plate which is engaged by a flyer plate to transmit the shock wave to the primary surface and the powder. Spawl plates are adhesively mounted on other surfaces of the block to act as momentum traps so as to reduce reflected waves in the block.

Flinn, John E. (Idaho Falls, ID); Korth, Gary E. (Blackfoot, ID)

1986-01-01

452

Synthesis, characterization, and microstructural evolution of ultrafine oxide powders  

NASA Astrophysics Data System (ADS)

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

Baranwal, Rita

453

Infrared characterization of uranium oxide powders using a metal light pipe  

Microsoft Academic Search

A light-pipe technique has been used to measure infrared spectra of UO, UO, and UO in the range 2000 to 450 cm⁻¹. Comparison with transmission spectra found in the literature indicates that the technique is very suitable for characterization of actinide powders and will therefore be a useful tool for future work, especially with hazardous materials such as actinides. The

B. Cort; J. F. Andrew; G. J. Hansen

1987-01-01

454

Structural and material approaches to bone tissue engineering in powder-based three-dimensional printing  

Microsoft Academic Search

This article reviews the current state of knowledge concerning the use of powder-based three-dimensional printing (3DP) for the synthesis of bone tissue engineering scaffolds. 3DP is a solid free-form fabrication (SFF) technique building up complex open porous 3D structures layer by layer (a bottom-up approach). In contrast to traditional fabrication techniques generally subtracting material step by step (a top-down approach),

A. Butscher; M. Bohner; S. Hofmann; L. Gauckler; R. Mller

2011-01-01

455

Structure and ferromagnetic properties of Co-doped ZnO powders  

Microsoft Academic Search

Single-phase Zn1?xCoxO (x=0.02, 0.04) powders were synthesized by a simple co-precipitation technique. X-ray diffraction analysis reveals that the Co-doped ZnO crystallizes in a wurtzite structure. The lattice constants of Co-doped ZnO powders decrease slightly when Co is doped into ZnO. Optical absorption spectra show a decrease in the bandgap with increasing Co content and also give an evidence of the

Xingyan Xu; Chuanbao Cao

2009-01-01

456

High strength Co-Cr-Mo alloy by hot isostatic pressing of powder.  

PubMed

Currently available cobalt alloy prostheses for total hip applications are fabricated by investment casting techniques. Instances of stem fracture have been reported due to metal fatigue secondary to stem loosening or cement breakdown. A new process has been developed which includes the preparation of ultraclean powder and subsequent consolidation of the powder by hot isostatic pressing. The resultant solid material is characterized by 100 percent density and ultrafine grain size. Prostheses prepared by the new process have the same biocompatibility and corrsion resistance as the conventional cast alloy but higher strength and fatgue resistance. PMID:454784

Bardos, D I

1979-01-01

457

Commercial exploitation of nanophase powder formed with exploding wire technology. Final report  

SciTech Connect

In this report, the region of the energy density under the uniform heating conditions, of the lower pressures of the gas environment and of the smaller wire diameter have been studied. Here, the theoretical investigations of exploding wire and powder formation processes are presented, the results of experimental investigations are discussed. It is demonstrated that exploding wire technique is able to produce nanophase powders of aluminum and iron oxides with the mean surface size of 30 nm or less at commercial quantities per hour and the cost of no more than $1,000 per kilogram. Here too, decisions for theoretical and technical activity during future program are recommended.

NONE

1996-10-01

458

Method for alloying lithium with powdered aluminum  

SciTech Connect

A method is described for alloying lithium with a powdered aluminum composition, which comprises: mixing a powdered aluminum composition with lithium dispersed in an inert, non-water absorbent, liquid medium to obtain a substantially homogeneous admixture, said liquid medium comprising substantially mutually exclusive fractions of major and minor liquid constituents of differentiating boiling points, said major liquid constituent having a boiling point below the melting point of lithium, said minor liquid constituent having a boiling point above the melting point of lithium but below the melting point of the alloy being produced, and heating said admixture to melt said lithium and vaporize said liquid medium to thereby obtain a decovered powdered alloy comprising aluminum and lithium.

Brown, S.W.

1993-08-03

459

A hydroxycarbonate route to superconductor precursor powders  

NASA Astrophysics Data System (ADS)

A precipitation process is described for the preparation of powders that can be thermally decomposed to form high critical temperature superconductors such as YBa2Cu3O7. In the process, a cationic solution (a concentrated chloride or nitrate solution) is instantaneously mixed with an anionic solution (a mixture of tetramethylammonium hydroxide and carbonate) to produce a metal-hydroxycarbonate precipitate having the metal stoichiometry of the desired superconducting oxide. The calcining and sintering of the precipitates is critical in controlling the structural integrity and morphology of the superconducting ceramics made from the chem-prep powders, as well as controlling superconducting properties. Under appropriate conditions, high density (greater than 95 percent) materials that exhibit good superconducting characteristics can be prepared with the chem-prep powders.

Voigt, J. A.; Bunker, B. C.; Doughty, D. H.; Lamppa, D. L.; Kimball, K. M.

460

Reactive plasma atomization of aluminum nitride powder  

SciTech Connect

Experiments were performed to synthesize AlN powders by reacting Al with N using a conventional dc arc plasma as heat source. Feeding Al powder into Ar/N plasma open to atmosphere produced mainly Al oxide. Experiments using a chamber backfilled with nitrogen suppressed the Al oxide, but little AlN was formed. A furnace and crucible assembly was designed to feed molten Al directly into a DeLaval nozzle attached to the face of the dc arc plasma gun. Resulting submicron powders show a significant increase in AlN formation. This was dependent on chamber pressure, plasma velocity, and molten liquid feed rate. Experimental parameters, equipment design, effects of atomization/vaporization/condensation are discussed.

Prichard, P.; Besser, M.; Sordelet, D.; Anderson, I.

1997-02-01

461

Detonation Properties of Powdered Ammonium Nitrate  

NASA Astrophysics Data System (ADS)

It was studied the parameters of detonation of Ammonium Nitrate (powder) The detonation properties of industrial explosive Ammonite 6 which is mixture of TNT 20% and AN 80% and THT powdered were compared. By using the known formula for detonation characteristic of the mixture of different HE it was estimated that the upper limit of detonation of AN by itself must be not less than 5 km per sec. The large-scale experiments with plane charges of AN with the thickness of layer of AN 200mm were made. The measured detonation velocity appeared to be 5 km per sec.

Deribas, Andrei A.; Simonov, Valery A.

1999-06-01

462

Synthesis of ultrafine powders by microwave heating  

DOEpatents

A method of synthesizing ultrafine powders using microwaves is described. A water soluble material is dissolved in water and the resulting aqueous solution is exposed to microwaves until the water has been removed. The resulting material is an ultrafine powder. This method can be used to make Al.sub.2 O.sub.3, NiO+Al.sub.2 O.sub.3 and NiO as well as a number of other materials including GaBa.sub.2 Cu.sub.3 O.sub.x.

Meek, Thomas T. (Knoxville, TN); Sheinberg, Haskell (Los Alamos, NM); Blake, Rodger D. (Santa Fe, NM)

1988-01-01

463

Synthesis of ultrafine powders by microwave heating  

DOEpatents

A method of synthesizing ultrafine powders using microwaves is described. A water soluble material is dissolved in water and the resulting aqueous solution is exposed to microwaves until the water has dissolved. The resulting material is an ultrafine powder. This method can be used to make Al/sub 2/O/sub 3/, NiO /plus/ Al/sub 2/O/sub 3/ and NiO as well as a number of other materials including GaBa/sub 2/Cu/sub 3/O/sub x/. 1 tab.

Meek, T.T.; Sheinberg, H.; Blake, R.D.

1987-04-24

464

Dry powder mixes comprising phase change materials  

DOEpatents

A free flowing, conformable powder-like mix of silica particles and a phase change material (PCM) is provided. The silica particles have a critical size of about 0.005 to about 0.025 microns and the PCM must be added to the silica in an amount of 75% or less PCM per combined weight of silica and PCM. The powder-like mix can be used in tableware items, medical wraps, tree wraps, garments, quilts and blankets, and particularly in applications for heat protection for heat sensitive items, such as aircraft flight recorders, and for preventing brake fade in automobiles, buses, trucks and aircraft.

Salyer, Ival O. (Dayton, OH)

1994-01-01

465

Dry powder mixes comprising phase change materials  

DOEpatents

A free flowing, conformable powder-like mix of silica particles and a phase change material (PCM) is provided. The silica particles have a critical size of about 0.005 to about 0.025 microns and the PCM must be added to the silica in an amount of 75% or less PCM per combined weight of silica and PCM. The powder-like mix can be used in tableware items, medical wraps, tree wraps, garments, quilts and blankets, and particularly in applications for heat protection for heat sensitive items, such as aircraft flight recorders, and for preventing brake fade in automobiles, buses, trucks and aircraft.

Salyer, Ival O. (Dayton, OH)

1995-01-01

466

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

467

Fabrication of ex situ processed MgB2 wires using nano carbon doped powder  

NASA Astrophysics Data System (ADS)

We fabricated ex situ MgB2 wires using C-doped MgB2 powder as a precursor in order to improve the core density of the wires and their C doping content. The C-doped powder was prepared with Mg, B, and nano carbon (NC) powders by the in situ technique and then MgB2-xCx (x = 0, 0.01, and 0.03) wires were fabricated by the ex situ technique using the powder-in-tube method. The phase formation, lattice change, and microstructure were characterized and correlated with the Tc and Jc variations. We observed that the ex situ wire had a higher core density than the in situ wire, however its morphology consisted of agglomerated particles, indicating that sintering and grain growth did not occur completely, even though the sintering was conducted at high temperature (1000 C). As the C content increased, Tc decreased, while the decrease of Jc with increasing magnetic field became smaller. The Jc of MgB1.97C0.03 wire made by the ex situ technique was 3.34 kA/cm2 at 6.6 T and 5 K which is comparable to that of the in situ wire (4.81 kA/cm2 at 6.6 T and 5 K).

Lee, C. M.; Park, J. H.; Hwang, S. M.; Lim, J. H.; Joo, J.; Kang, W.-N.; Kim, C.-J.

2009-10-01

468

Hot Superplastic Powder Forging for Transparent nanocrystalline Ceramics  

SciTech Connect

The program explored a completely new, economical method of manufacturing nanocrystalline ceramics, Hot Superplastic Powder Forging (HSPF). The goal of the work was the development of nanocrystalline/low porosity optically transparent zirconia/alumina. The high optical transparency should result from lack of grain boundary scattering since grains will be smaller than one tenth the wavelength of light and from elimination of porosity. An important technological potential for this process is manufacturing of envelopes for high-pressure sodium vapor lamps. The technique for fabricating monolithic nanocrystalline material does not begin with powder whose particle diameter is <100 nm as is commonly done. Instead it begins with powder whose particle diameter is on the order of 10-100 microns but contains nanocrystalline crystallites <<100 nm. Spherical particles are quenched from a melt and heat treated to achieve the desired microstructure. Under a moderate pressure within a die or a mold at temperatures of 1100C to 1300C densification is by plastic flow of superplastic particles. A nanocrystalline microstructure results, though some features are greater than 100nm. It was found, for instance, that in the fully dense Al2O3-ZrO2 eutectic specimens that a bicontinuous microstructure exists containing <100 nm ZrO2 particles in a matrix of Al2O3 grains extending over 1-2 microns. Crystallization, growth, phase development and creep during hot pressing and forging were studied for several compositions and so provided some details on development of polycrystalline microstructure from heating quenched ceramics.

Cannon, W. Roger

2006-05-22

469

Soil Amendement by green supplement: dry cowdung powder  

NASA Astrophysics Data System (ADS)

Soil is a heavenly resource, a living, breathing and ever changing dynamic ecosystem. Retrogression and degradation of soil system is the result of continuous encroachment done by global anthropogenic activities. Mother earth's monition has increased the local concern to explore solution for the healthy sustainability of soil. At this hour of need it is crucial to regain the health of soil by utilizing eco-friendly solution and the promising one is Dry Cow Dung powder. Cow Dung is bio- organic, complex, polymorphic fecal matter of the bovine species, enriched with Humic acid' (HA), Fulvic Acid' etc. The HA in Cow Dung has been extracted using Neutralization Reaction and its presence is confirmed by comparing it with FTIR spectra of Std HA (IHSS). Property of metal ion adsorption of Standard and Extracted HA has been confirmed using Tracer Technique'. Cow Dung is renewable, easy and freely available with least contaminants as the process of Humification takes place during drying stage hence speciation of any type is not required due to its Biological matrix. Any pre or post conditioning of cow dung powder is not required reducing undesired chemical sink in milieu. It will surely contribute in closing the natural nutrient cycle and increase the fertility as well as carbon pool of soil due to abundance of useful microflora. If compared to present day usage of synthetic and semi- synthetic products, employing Dry Cow Dung powder as agrarian booster will be surely a Green solution! It's rightly said that "The nation which destroys its soil, destroys itself!", hence we need to pursue instant remedies to mitigate our self destruction because healthy soil is the only life line for Survival!

Barot, N. S.; Bagla, H.

2009-04-01

470

" Soil amendement by green supplement : Dry cowdung powder"  

NASA Astrophysics Data System (ADS)

Soil is a heavenly resource, a living, breathing and ever changing dynamic ecosystem. Retrogression and degradation of soil system is the result of continuous encroachment done by global anthropogenic activities. Mother earth's monition has increased the local concern to explore solution for the healthy sustainability of soil. At this hour of need it is crucial to regain the health of soil by utilizing eco-friendly solution and the promising one is Dry Cow Dung powder. Cow Dung is bio- organic, complex, polymorphic fecal matter of the bovine species, enriched with Humic acid' (HA), Fulvic Acid' etc. The HA in Cow Dung has been extracted using Neutralization Reaction and its presence is confirmed by comparing it with FTIR spectra of Std HA (IHSS). Property of metal ion adsorption of Standard and Extracted HA has been confirmed using Tracer Technique'. Cow Dung is renewable, easy and freely available with least contaminants as the process of Humification takes place during drying stage hence speciation of any type is not required due to its Biological matrix. Any pre or post conditioning of cow dung powder is not required reducing undesired chemical sink in milieu. It will surely contribute in closing the natural nutrient cycle and increase the fertility as well as carbon pool of soil due to abundance of useful microflora. If compared to present day usage of synthetic and semi- synthetic products, employing Dry Cow Dung powder as agrarian booster will be surely a Green solution! It's rightly said that "The nation which destroys its soil, destroys itself!", hence we need to pursue instant remedies to mitigate our self destruction because healthy soil is the only life line for Survival!

Barot, N.; Bagla, H.

2009-04-01

471

Characterization of Hafnia Powder Prepared from an Oxychloride Sol Gel  

SciTech Connect

Hafnium containing compounds are of great importance to the semiconductor industry as a replacement for Si(O,N) with a high- gate dielectric. Whilst Hf is already being incorporated into working devices1, much is still to be understood about it. Here we investigate the crystallisation processes and chemistry of bulk HfO2 powders which will aid in interpretation of reactions and crystallisation events occurring in thin films used as gate dielectrics. Amorphous HfO2 powder was prepared via a sol-gel route using hafnium oxychloride (HfOCl2 xH2O) as a precursor. The powders were subjected to various heat treatments and analysed using x-ray diffraction (XRD) and thermal analysis techniques. It was found that a large change in the crystallisation pathway occurred when the sample was heated in an inert environment compared with in air. Instead of the expected monoclinic phase (m-HfO2), tetragonal HfO2 (t-HfO2) also formed under these conditions and was observed up to temperatures of ~760 C. The t-HfO2 particles, which are less than 30nm in size, eventually transform into m-HfO2 on further heating. Possible mechanisms for the crystallisation of t-HfO2 are discussed. It is proposed that within this temperature range t-HfO2 is stabilised due to the presence of oxygen vacancies in the inert environment, forming by the reduction of HfIV to HfIII. As the crystal grows in size as the temperature increases there are too few oxygen vacancies left in the structure to continue stabilising the t-HfO2 phase and so transformation to m-HfO2 occurs.

McGilvery, Catriona M. [Imperial College, London; De Gendt, S [Imperial College, London; Payzant, E Andrew [ORNL; MacKenzie, M [Imperial College, London; Craven, A J [Imperial College, London; McComb, D W [Imperial College, London

2011-01-01

472

Radio frequency (rf) plasma spheroidized HA powders: powder characterization and spark plasma sintering behavior.  

PubMed

The present study describes the synthesis of spheroidized hydroxyapatite (HA) powders using a radio frequency (rf) inductively coupled plasma (ICP) torch. The spheroidized powders were consolidated through a spark plasma sintering (SPS) system. The microstructure and crystallographic phases in the synthesized powders were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffractometry (XRD) and Raman spectrometry. Results showed that the HA feedstock decomposed after rf plasma processing. Crystalline HA, alpha-tri-calcium phosphate (alpha-TCP), tetra-calcium phosphate (TTCP) and calcium oxide (CaO) were detected in the plasma-spheroidized powders. Raman spectra results indicated strong presence of amorphous calcium phosphate (ACP) in the spheroidized powders. The particle size distribution and specific surface area were influenced through the rf plasma working plate power levels. The sintering behavior of the rf plasma synthesized powders was analyzed through the SPS process and the results indicated that the spheroidized powders commence sintering at approximately 900 degrees C and through to 1150 degrees C. After sintering above 1100 degrees C for 3min, the relative densities of the SPS compacts reached 96% of the theoretical value. The SPS compacts were immersed in simulated body fluids (SBF) for different durations and the results confirmed their bioactivities. PMID:15585221

Xu, J L; Khor, K A; Gu, Y W; Kumar, R; Cheang, P

2005-05-01

473

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

474

Physico-chemistry and cytotoxicity of ceramics: part I: characterization of ceramic powders.  

PubMed

The morphology of Al2O3, ZrO2/Y2O3, AIN, B4C, BN, SiC, Si3N4, TiB2, TiC, TiN ceramic, graphite and diamond powders has been studied by scanning electron microscopy (SEM) and the specific area of each powder was determined with the BET method. X-ray diffraction (XRD) investigations have been carried out in order to evaluate the crystallinity and determine the constitutive phases. The chemical composition was assessed by classical chemical analyses and by X-ray microprobe; some powders were studied by the laser micro-Raman technique. Correlations have been established between all these results. PMID:15348756

Dion, I; Rouais, F; Baquey, C; Lahaye, M; Salmon, R; Trut, L; Cazorla, J P; Huong, P V; Monties, J R; Havlik, P

1997-05-01

475

Characterization of 17-4PH stainless steel powders produced by supersonic gas atomization  

NASA Astrophysics Data System (ADS)

17-4PH stainless steel powders were prepared using a supersonic nozzle in a close-coupled gas atomization system. The characteristics of powder particles were carried out by means of a laser particle size analyzer, scanning electron microscopy (SEM), and the X-ray diffraction (XRD) technique. The results show that the mass median particle diameter is about 19.15 ?m. Three main types of surface microstructures are observed in the powders: well-developed dendrite, cellular, and cellular dendrite structure. The XRD measurements show that, as the particle size decreases, the amount of fcc phase gradually decreases and that of bcc phase increases. The cooling rate is inversely related to the particle size, i.e., it decreases with an increase in particle size.

Zhao, Xin-Ming; Xu, Jun; Zhu, Xue-Xin; Zhang, Shao-Ming; Zhao, Wen-Dong; Yuan, Guo-Liang

2012-01-01

476

Surface composition of industrial spray-dried milk powders. 1. Development of surface composition during manufacture  

Microsoft Academic Search

Development of the surface composition of milk powders during manufacture was investigated in three industrial spray-dried milk powders (skim milk powder, whole milk powder and instant whole milk powder). Samples were obtained from commercial production plants and were collected at different manufacturing stages. As the powder properties of milk powder are defined in spray-drying and the subsequent manufacturing processes, the

Esther H.-J. Kim; Xiao Dong Chen; David Pearce

2009-01-01

477

Influence of storage humidity on the in vitro inhalation properties of salbutamol sulfate dry powder with surface covered lactose carrier.  

PubMed

The influence of storage humidity on the in vitro inhalation properties of salbutamol sulfate dry powder with surface covered lactose carrier was investigated. In the present study, drug/carrier powder mixtures were prepared consisting of micronized salbutamol sulfate and lactose carriers with different particle surface conditions prepared by surface covering. Lactose carrier surfaces were covered with vegetable magnesium stearate (Mg-St-V) by a high-speed elliptical-rotor-type powder mixer (Theta-Composer). These powder mixtures were aerosolized by a Jethaler), and the in vitro inhalation properties of salbutamol sulfate were evaluated by a twin impinger. Compared with the powder mixed with uncovered lactose carrier, the in vitro inhalation properties of the powder mixture prepared using the surface covered lactose carrier were little decreased with increased in relative humidity (RH), showing that the in vitro inhalation properties of salbutamol sulfate were improved at high RH. Using this surface covering technique would thus be valuable for storage humidity of dry powder inhalation (DPI) with lactose carrier particles. PMID:15056961

Iida, Kotaro; Hayakawa, Youhei; Okamoto, Hirokazu; Danjo, Kazumi; Luenberger, Hans

2004-04-01

478

Mechanism to Diminish the Supercooling of the Tin Freezing Point by using Graphite Powder  

NASA Astrophysics Data System (ADS)

The formation of crystallization centers from extremely pure molten tin is normally associated with deep supercooling. This deep supercooling is inconvenient for the operation of tin freezing-point cells, especially for sealed tin fixed-point cells without a holder to facilitate removal from the furnace. Researchers of the National Institute of Metrology (NIM) intended and succeeded in reducing this deep supercooling by adding fine and pure graphite powders to tin fixed-point cells without influencing the fixed-point temperature, but the mechanism is yet to be properly clarified. The principle of heterogeneous nucleation indicates that a decrease of the contact angle of the crystalline nucleus on the substrate surface results in a significant reduction of supercooling required for initiation of nucleation. The heterogeneous theory is utilized by the authors of this paper to give a reasonable description of the mechanism of supercooling reduction by addition of graphite powder. It is demonstrated that the freezing plateau can be realized by the natural cooling of the tin cell within the furnace without using the outside nucleation technique. The maximum temperature of the freezing curves of the tin cell with graphite powder agrees well with the reference tin cell without the graphite powder, and the cells with graphite powder show good consistency.

Zhang, Jin Tao; Wang, Y. N.

2008-06-01

479

Pulmonary delivery of dry powders to rats: tolerability limits of an intra-tracheal administration model.  

PubMed

The inhaled route is increasingly developed to deliver locally acting or systemic therapies, and rodent models are used to assess tolerance before clinical studies. Endotracheal intubation of rats with a probe which generates powder aerosols enables controlled administration of drug directly into the respiratory tract. However, preliminary observations of intratracheal powder administration procedures have raised concerns with regard to pulmonary safety. The aim of the present work was to evaluate the safety of intra-tracheal administration of dry powder in a rat model. Sixty animals were administered various volumes of air alone, lactose or magnesium stearate through a Microsprayer() (Pencentury, USA). The mass of powder actually delivered to each animal was calculated. Rats were sacrificed immediately after administration, and the lungs, trachea and larynx were removed and examined for gross pathology. The mass of powder delivered varied, the full dose being rarely delivered. About one third of the administration procedures resulted in respiratory failure, and macroscopic pulmonary lesions were observed in about 55% of animals. Lung damages were observed with air alone, lactose and magnesium stearate. In conclusion, artifacts observed with this technique may limit the relevance of the model. These observations are particularly important in the context of regulatory toxicity studies. PMID:22609125

Guillon, A; Montharu, J; Vecellio, L; Schubnel, V; Roseau, G; Guillemain, J; Diot, P; de Monte, M

2012-05-15

480

SANS study of microstructural inhomogeneities on Al nano-powder compacts  

NASA Astrophysics Data System (ADS)

The nano-crystalline materials have excellent mechanical and electrical properties compared to conventional materials. These advantages mainly come from their nano-sized grain structure. Usually the nano-crystalline materials are fabricated using nano powder. The optimum consolidation process is essential to obtain a fully densified structure. The quantitative characterization of remaining pores is important to study the consolidation process. SANS is the best technique to characterize the nano sized inhomogeneities in bulk samples. Al nano powder was synthesized by pulsed wire evaporation (PWE) method and the nano-powder compacts were fabricated by magnetic pulse compaction (MPC) method. The Aluminum oxide was observed by transmission electron microscopy (TEM) at the surface of Al nano powder. The small angle neutron scattering experiments were performed both at the instrument V4 in HMI and at the SANS facility in Korea Atomic Energy Research Institute (KAERI). The SANS data measured in KAERI were compared with the SANS data measured in HMI. The scattering intensity at high Q region increases with decreasing relative density, while the intensity at low Q region increases with increasing relative density in the Al nano powder compacts. The scattering intensity depends on the content of residual pores and Al oxide particles. The volume fraction of Al oxide particle increases with relative density due to the fragmentation of Al oxide layer. The extra scattering at low Q region results from the presence of Al oxide particles.

Han, Young Soo; Seong, Baek Seok; Lee, Chang Hee; Lee, Geun Hee; Rhee, Chang Kyu; Kim, Whung Whoe; Wiedenmann, A.

2004-07-01

481

Ferrous Powder Metal Preform Forging Methods.  

National Technical Information Service (NTIS)

The research is designed to examine the three ferrous powder metal preform forging methods currently under consideration by the U.S. Army. The examination will answer the following question: which method is best for a particular complexity of parts. One o...

M. A. Perlman

1975-01-01

482

Electrochemical properties of nanodiamond powder electrodes  

Microsoft Academic Search

Detonation-synthesized nanocrystalline diamond is a novel carbon material. Its increased electrical conductivity, due to the features of giant specific surface area and large numbers of surface defects as well as the cluster structure, makes it possible to be used as an electrode material. Nanodiamond powder electrodes were fabricated and the electrochemistry was investigated by cyclic voltammetry and AC impedance measurement.

J. B. Zang; Y. H. Wang; S. Z. Zhao; L. Y. Bian; J. Lu

2007-01-01

483

Strain analysis for extrusion of powder metals  

Microsoft Academic Search

A method is described for determining the strain distribution during axisymmetric extrusion of powder metals. Density variations\\u000a in these materials are included in the analysis. The method examines these changes together with the laminar flow pattern\\u000a to determine strain rates and, ultimately, strains.

D. G. Berghaus; R. J. Primas; H. B. Peacock

1988-01-01

484

Roll Forming Strip From Oxide Powders.  

National Technical Information Service (NTIS)

The roll forming of oxide powders was studied in an investigation to find the conditions and parameters required to make satisfactory ceramic strip. High-quality porous or dense alumina, zirconia, and porcelain shapes were made by sintering strip roll-for...

B. L. Forkner H. J. Kelly H. M. Harris

1970-01-01

485

Dispersant for aqueous slurry of coal powder  

SciTech Connect

A dispersant for forming an aqueous slurry of coal powder having a good flowability, which comprises as the active ingredient at least one member selected from sulfonation products of polycyclic aromatic compounds which may have a hydrocarbon group as a substituent, salts thereof and formaldehyde condensates thereof.

Moriyama, N.; Watanabe, S.; Yamamura, M.

1982-05-18

486

Sonochemical method for producing titanium metal powder  

Microsoft Academic Search

We demonstrate a sonochemical method for producing titanium metal powder. The method uses low intensity ultrasound in a hydrocarbon solvent at near-ambient temperatures to first create a colloidal suspension of liquid sodiumpotassium alloy in the solvent and then to reduce liquid titanium tetrachloride to titanium metal under cavitation conditions. XRD data collected for the reaction products after the solvent removal

Ion C. Halalay; Michael P. Balogh

2008-01-01

487

21 CFR 73.1646 - Bronze powder.  

Code of Federal Regulations, 2013 CFR

...tin. It contains small amounts of stearic or oleic acid as lubricants. (2) Color additive mixtures for drug use made with...minimum). Aluminum, zinc, tin, and copper content shall be based on the weight of the dried powder after being thoroughly...

2013-04-01

488

Transparent ferroelectric ceramic from chemically synthesized powders  

Microsoft Academic Search

Chemical synthesis by concomitant precipitation of metallic ions for obtaining a PLZT 10\\/65\\/35 composition starting from hydroxides and oxalates was made. Another task was the sintering of oxide powders obtained by thermal decomposition of synthesized precipitates using hot pressing method followed of heat treatment in oxygen stream.

Sorin Jinga; Cristian Onose

2000-01-01

489

LaRC powder prepreg system  

Microsoft Academic Search

Thermoplastic prepregs of LARC-TPI have been produced in a fluidized bed unit on spread continuous fiber tows. The powders are melted on the fibers by radiant heating to adhere the polymer to the fiber. This process produces tow prepreg uniformly without imposing severe stress on the fibers or requiring long high temperature residence times for the polymer. Unit design theory

R. M. Baucom; J. M. Marchello

1990-01-01

490

Microstructural analysis of RPC (Reactive Powder Concrete)  

Microsoft Academic Search

Reactive Powder Concretes (RPC) are characterized by high silica fume content and very low water to cement ratio. Granulometry and heat treatment were optimized to obtain excellent mechanical and durability properties. The study of several RPC compositions by Mercury Porosimetry, Thermogravimetric Analysis and X-ray diffraction made it possible to better understand their microstructural properties depending on their heat treatment. Influence

Marcel Cheyrezy; Vincent Maret; Laurent Frouin

1995-01-01

491

Frontal dynamics of powder snow avalanches  

NASA Astrophysics Data System (ADS)

We analyze frontal dynamics of dilute powder snow avalanches sustained by rapid blow-out behind the front. Such material injection arises as a weakly cohesive snow cover is fluidized by the very pore pressure gradient that the particle cloud induces within the snowpack. We model cloud fluid mechanics as a potential flow consisting of a traveling source of denser fluid thrust into a uniform airflow. Stability analysis of a mass balance involving snow cover and powder cloud yields relations among scouring depth, frontal height, speed, mixed-mean density, and impact pressure when the frontal region achieves a stable growth rate. We compare predictions with field measurements, show that powder clouds cannot reach steady frontal speed on a uniform snowpack with constant cloud width and derive a criterion for cloud ignition. Because static pressure is continuous across the mean air-cloud interface and deviatoric stresses are negligible, frontal acceleration is insensitive to local slope, but instead arises from a deficit of flow-induced suction in the wake. We calculate how far a powder cloud travels until its frontal mixed-mean density becomes stable, and show how topographic spread can hasten its collapse.

Carroll, C. S.; Louge, M. Y.; Turnbull, B.

2013-06-01

492

Moisture Uptake by Plutonium Oxide Powder.  

National Technical Information Service (NTIS)

In the scope of installation safety and criticality studies, an assessment was made of moisture uptake by plutonium oxide powder used for oxide fuels. The effects of exposure time, atmospheric relative humidity (9 to 98%), calcination temperature (400-1 1...

A. Benhamou J. P. Beraud

1980-01-01

493

21 CFR 169.179 - Vanilla powder.  

Code of Federal Regulations, 2010 CFR

...specified name of the food is Vanilla powder _-fold or _-fold vanilla powder, except that if sugar is the optional...However, if the strength of the article is less than 2-fold, the term _-fold is omitted from the...

2009-04-01

494

21 CFR 169.179 - Vanilla powder.  

Code of Federal Regulations, 2010 CFR

...specified name of the food is Vanilla powder _-fold or _-fold vanilla powder, except that if sugar is the optional...However, if the strength of the article is less than 2-fold, the term _-fold is omitted from the...

2010-04-01

495

A PLASTICITY MODEL FOR POWDER COMPACTION PROCESSES  

Microsoft Academic Search

An endochronic constitutive model for cold powder compaction processes is developed. Although the concept of yield surface has not been explicitly assumed in the endochronic theory, it is demonstrated that the cone-cap yield surface can be derived as a special case of the proposed endochronic model. The plastic flow rule and the dilatancy condition of the model are derived and

A. Bakhshiani; M. Mofid; A. R. Khoei

496

Reactive PZT precursor powder by coprecipitation  

Microsoft Academic Search

Lead, zirconium and titanium were coprecipitated from their aqueous salt solutions using oxalic acid. The precipitate on heating to 850 C gave phase pure PZT powder which showed good sinterability. The average grain size in the pellets sintered at 900 C for 6 h was about 1 ?m. Barium and strontium were found to coprecipitate with lead facilitating partial substitution.

K. Rama Mohana Rao; A. V. Prasada Rao; S. Komarneni

1996-01-01

497