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1

Henry A. Kurtz http://www.chem.memphis.edu/kurtz/  

E-print Network

for Predicting NLO Properties" H.A. Kurtz and D.S. Dudis, in Reviews in Computational Chemistry, K.B. Lipkowitz-racially identifiable student body. CROMIUM (Computational Research on Materials Institute) Department of Chemistry The University of Memphis Memphis, TN 38152-6060 U of M Computational Chemistry at a Glance 路 There are currently

Dasgupta, Dipankar

2

Preparation techniques for ceramic waste form powder  

SciTech Connect

The electrometallurgical treatment of spent nuclear fuels result in a chloride waste salt requiring geologic disposal. Argonne National Laboratory (ANL) is developing ceramic waste forms which can incorporate this waste. Currently, zeolite- or sodalite-glass composites are produced by hot isostatic pressing (HIP) techniques. Powder preparations include dehydration of the raw zeolite powders, hot blending of these zeolite powders and secondary additives. Various approaches are being pursued to achieve adequate mixing, and the resulting powders have been HIPed and characterized for leach resistance, phase equilibria, and physical integrity.

Hash, M.C.; Pereira, C.; Lewis, M.A. [and others

1997-08-01

3

Laser cladding using the powder blowing technique  

Microsoft Academic Search

A series of laser-clad samples have been produced using a 5 kW CO2 laser and a powder blowing technique. With the correct conditions, a fused bead of alloy up to 5 mm wide and 1 mm thick can be formed on a surface. A wide variety of combinations of base plate and clad materials have been used, including base plates

J. M. Yellup

1995-01-01

4

Physical and chemical characterization techniques for metallic powders  

SciTech Connect

Systematic studies have been carried out on two different powder materials used for additive manufacturing: stainless steel and cobalt-chrome. An extensive array of characterization techniques were applied to these two powders. The physical techniques included laser-diffraction particle-size analysis, X-ray computed tomography for size and shape analysis, and optical and scanning electron microscopy. Techniques sensitive to chemistry included X-ray diffraction and energy-dispersive analytical X-ray analysis. The background of these techniques will be summarized and some typical findings comparing different samples of virgin additive manufacturing powders, taken from the same lot, will be given. The techniques were used to confirm that different samples of powder from the same lot were essentially identical, within the uncertainty of the measurements.

Slotwinski, J. A. [Intelligent Systems Division, Engineering Laboratory, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, MD 20899 (United States); Stutzman, P. E.; Ferraris, C. F.; Watson, S. S.; Peltz, M. A.; Garboczi, E. J. [Materials and Structural Systems Division, Engineering Laboratory, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, MD 20899 (United States)

2014-02-18

5

Application of physical and chemical characterization techniques to metallic powders  

SciTech Connect

Systematic studies have been carried out on two different powder materials used for additive manufacturing: stainless steel and cobalt-chrome. The characterization of these powders is important in NIST efforts to develop appropriate measurements and standards for additive materials and to document the property of powders used in a NIST-led additive manufacturing material round robin. An extensive array of characterization techniques was applied to these two powders, in both virgin and recycled states. The physical techniques included laser diffraction particle size analysis, X-ray computed tomography for size and shape analysis, and optical and scanning electron microscopy. Techniques sensitive to chemistry, including X-ray diffraction and energy dispersive analytical X-ray analysis using the X-rays generated during scanning electron microscopy, were also employed. Results of these analyses will be used to shed light on the question: how does virgin powder change after being exposed to and recycled from one or more additive manufacturing build cycles? In addition, these findings can give insight into the actual additive manufacturing process.

Slotwinski, J. A. [Intelligent Systems Division, Engineering Laboratory, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, MD 20899 (United States); Watson, S. S.; Stutzman, P. E.; Ferraris, C. F.; Peltz, M. A.; Garboczi, E. J. [Materials and Structural Systems Division, Engineering Laboratory, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, MD 20899 (United States)

2014-02-18

6

Nano powders, components and coatings by plasma technique  

DOEpatents

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 the ultra pure, ultra fine and nano product. With this technique, powders have been made 20 nanometers in size in a system capable of a bulk production rate of more than 10 lbs/hr. The process is particularly applicable to tungsten, molybdenum, rhenium, tungsten carbide, molybdenum carbide and other related materials.

McKechnie, Timothy N. (Brownsboro, AL); Antony, Leo V. M. (Huntsville, AL); O'Dell, Scott (Arab, AL); Power, Chris (Guntersville, AL); Tabor, Terry (Huntsville, AL)

2009-11-10

7

A Modeling-Based Technique for Nondestructive Evaluation of Metal Powders Undergoing Microwave Sintering  

E-print Network

A Modeling-Based Technique for Nondestructive Evaluation of Metal Powders Undergoing Microwave, microwave imaging, neural network applications, nondestructive testing. I. INTRODUCTION Microwave (MW the development of suitable means of nondestructive evaluation (NDE) of powder samples under microwave 978

Yakovlev, Vadim

8

Checklists for powder inhaler technique: a review and recommendations.  

PubMed

Turbuhaler and Diskus are commonly used powder inhaler devices for patients with respiratory disease. Their effectiveness is limited in part by a patient's ability to use them correctly. This has led to numerous studies being conducted over the last decade to assess the correct use of these devices by patients and health care professionals. These studies have generally used device-specific checklists to assess technique, this being the most feasible and accessible method for assessment. However, divergence between the checklists and scoring systems for the same device in different studies makes direct comparison of results difficult and at times inappropriate. Little evidence is available to assess the relative importance of different criteria; however, brief patient training based on specific inhaler technique checklists leads to significant improvement in asthma outcomes. This paper reviews common checklists and scoring systems used for Turbuhaler and Diskus, discusses the problem of heterogeneity between different checklists, and finally recommends suitable checklists and scoring systems for these devices based on the literature and previous findings. Only when similar checklists are used across different research studies will accurate comparisons and meta-analysis be possible. PMID:24129338

Basheti, Iman A; Bosnic-Anticevich, Sinthia Z; Armour, Carol L; Reddel, Helen K

2014-07-01

9

A Comparison of Cocrystal Structure Solutions from Powder and Single Crystal Techniques  

SciTech Connect

We demonstrate the effectiveness and accuracy of high resolution powder diffraction for determination of cocrystal structures through a double-blind study. Structures of 10 cocrystals of varying complexity were determined independently using single crystal and powder techniques. The two methodologies give identical molecular packing and hydrogen bond topology, and an rms difference in covalent bond lengths of 0.035 {angstrom}. Powder techniques are clearly sufficient to establish a complete characterization of cocrystal geometry.

S Lapidus; P Stephens; K Arora; T Shattock; M Zaworotko

2011-12-31

10

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

11

Synchrotron and laboratory studies utilizing a new powder diffraction technique  

SciTech Connect

We have developed a new type of powder diffractometer that is much more efficient than existing methods. The diffractometer has the potential of both high count rates and very high resolution when used at a synchrotron source. The laboratory based instrument has an order of magnitude improvement in count rate over existing methods. The method uses a focusing diffracted beam monochromator in combination with a multichannel detector. The incident x-rays fall on a flat plate or capillary sample and are intercepted by a bent focusing monochromator which has the focus of the bend at the sample surface. The powder diffraction lines emerging from the bent crystal monochromator are detected by a linear or 2-dimensional detector. This allows us to eliminate the background from fluorescence or other scattering and to take data over a range of 3[degrees] to 4[degrees] instead of one angle at a time thereby providing a large improvement over conventional diffractometers. Results are presented for fluorapatite Fe[sub 2]O[sub 3], and a high-TC superconductor.

Knapp, G.S.; Beno, M.A.; Jennings, G.; Engbretson, M.; Ramanathan, M.

1992-10-01

12

Synchrotron and laboratory studies utilizing a new powder diffraction technique  

SciTech Connect

We have developed a new type of powder diffractometer that is much more efficient than existing methods. The diffractometer has the potential of both high count rates and very high resolution when used at a synchrotron source. The laboratory based instrument has an order of magnitude improvement in count rate over existing methods. The method uses a focusing diffracted beam monochromator in combination with a multichannel detector. The incident x-rays fall on a flat plate or capillary sample and are intercepted by a bent focusing monochromator which has the focus of the bend at the sample surface. The powder diffraction lines emerging from the bent crystal monochromator are detected by a linear or 2-dimensional detector. This allows us to eliminate the background from fluorescence or other scattering and to take data over a range of 3{degrees} to 4{degrees} instead of one angle at a time thereby providing a large improvement over conventional diffractometers. Results are presented for fluorapatite Fe{sub 2}O{sub 3}, and a high-TC superconductor.

Knapp, G.S.; Beno, M.A.; Jennings, G.; Engbretson, M.; Ramanathan, M.

1992-10-01

13

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

14

Microstructural evolution and dielectric properties of 1D AlN powders synthesized by microwave technique  

NASA Astrophysics Data System (ADS)

Low temperature synthesis of Aluminum nitride (AlN) powders through NH4Cl assisted nitridation have been studied by microwave technique. The effect of processing time on the synthesis of AlN powders has been investigated. The optimum processing time was determined to be 120 min at 630 W, 200 癈. The powders were characterized by X-ray diffraction method (XRD), Scanning electron microscopy (SEM), Energy dispersive X-ray analyzer (EDS), Fourier transform infrared spectrometer (FTIR) and Impedance analyzer. XRD results revealed that the product has wurtzite phase of AlN. SEM micrographs show a 1D nanorod of AlN with a granular morphology. FTIR spectra exhibit A1 (TO) and E1 (LO) modes of wurtzite AlN. Dielectric properties of the powders were investigated by means of C-V and C-f and ?'-f characteristics. The reported results indicate a reasonable quality of the obtained AlN powders with high dielectric constant, suitable for application in the fabrication of specific electronic devices.

VasanthiPillay, V.; Vijayalakshmi, K.

2012-06-01

15

Return To: Gail Kurtz, Investments and Endowment Management Re: Endowment Title 54-department #: 54-  

E-print Network

Page 1 Return To: Gail Kurtz, Investments and Endowment Management From: Date: Re: Endowment Title 54-department #: 54- Endowment Contact/Administrator Form Please complete and return this form to identify those persons designated as the contact/administrator of your department's endowment(s

de Doncker, Elise

16

Early Cenozoic decoupling of the global carbon and sulfur cycles A. C. Kurtz,1  

E-print Network

Early Cenozoic decoupling of the global carbon and sulfur cycles A. C. Kurtz,1 L. R. Kump,2 M. A 2003; published 4 December 2003. [1] Changes in carbon and sulfur cycling over geologic time may have: Carbon cycling; 4842 Oceanography: Biological and Chemical: Modeling; 1040 Geochemistry: Isotopic

Zachos, James

17

Thomas G. Kurtz, Mathematics Philip O'Leary, Engineering Professional Development  

E-print Network

路 Thomas G. Kurtz, Mathematics 路 Philip O'Leary, Engineering Professional Development 路 Stephen M room at the airport in Madison, Wisconsin. T Other Areas of Application 路 Emergency planning 路 Operations research Center Director Vicki Bier has more than twenty years of experience in risk analysis

Sheridan, Jennifer

18

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

Microsoft Academic Search

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

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

2006-01-01

19

Optimization of headspace solid-phase microextraction technique for extraction of volatile smokeless powder compounds in forensic applications.  

PubMed

Smokeless powders are low explosives and are potentially found in cases involving firearms and improvised explosive devices. Apart from inorganic compound analysis, forensic determination of organic components of these materials appears as a promising alternative, especially the chromatographic techniques. This work describes the optimization of a solid-phase microextraction technique using an 85 ?m polyacrylate fiber followed by gas chromatography-flame ionization detection for smokeless powder. A multivariate experimental design was performed to optimize extraction-influencing parameters. A 2(4) factorial first-order design revealed that sample temperature and extraction time were the major influencing parameters. Doehlert matrix design has subsequently selected 66癈 and 21 min as the compromised conditions for the two predetermined parameters. This extraction technique has successfully detected the headspace compounds of smokeless powders from different ammunition types and allowed for their differentiation. The novel technique allows more rapid sample preparation for chromatographic detection of smokeless powders. PMID:24611488

Chang, Kah Haw; Yew, Chong Hooi; Abdullah, Ahmad Fahmi Lim

2014-07-01

20

Experimental Technique for Direct Observation of Onset of Reaction in Shocked Powder Mixtures  

NASA Astrophysics Data System (ADS)

A new experimental technique was developed to directly observe the onset of shock initiation in powder mixtures contained in recovery capsules over time scales ranging from hundreds of nanoseconds to at least hundreds of milliseconds. Simultaneously with a thermocouple embedded in the test mixture to monitor bulk temperature changes, a photomultiplier tube detected light emissions produced by the reacting sample. A particular window/optic fiber system was developed that remained intact and did not move during the experiment. A T-shaped polycarbonate window was placed into a steel recovery capsule, which was held solidly in place in a heavy steel anvil designed to protect the fiber optic and to prevent motion of the polycarbonate window. Samples of as-blended 5Ti+3Si powders and ball-milled mixtures 5Ti+3Si were tested in this setup. In all experiments, a weak light emission peak was observed upon shock passage followed by much more intense light emissions beginning a few milliseconds to a few hundreds of milliseconds later. The intense light emissions occurred at approximately the same time as a bulk temperature increase measured with the thermocouple. These results suggest that only a very small fraction of the sample was initiated by the shock. This setup shows promise for further studies of shock initiation in reactive powders.

Jett, Fran鏾is-Xavier; Goroshin, Sam; Higgins, Andrew; Frost, David; Lee, Julian

2011-06-01

21

Experimental technique for direct observation of onset of reaction in shocked powder mixtures  

NASA Astrophysics Data System (ADS)

A new experimental technique was developed to directly observe the onset of shock initiation in powder mixtures contained in recovery capsules over time scales ranging from hundreds of nanoseconds to at least hundreds of milliseconds. Simultaneously with a thermocouple embedded in the test mixture to monitor bulk temperature changes, a photomultiplier tube detected light emissions produced by the reacting sample. A window/optic fiber system was developed that remained intact and did not move during the experiment. A polycarbonate window was placed into a steel recovery capsule, which was held solidly in place in a steel anvil designed to protect the fiber optic and to prevent motion of the window. Samples of as-blended 5Ti+3Si powders and ball-milled mixtures 5Ti+3Si were tested in this setup. In all experiments, a weak light emission peak was observed upon shock passage followed by much more intense light beginning a few milliseconds to a few hundreds of milliseconds later. The intense light emissions occurred at approximately the same time as a bulk temperature increase measured with the thermocouple. These results suggest that only a very small fraction of the sample was initiated by the shock.

Jett, Francois-Xavier; Goroshin, Sam; Higgins, Andrew; Frost, David; Lee, Julian

2012-03-01

22

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

SciTech Connect

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

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

2012-11-15

23

[A quantitation method for andrographolide and dehydroandrographolide by X-ray powder diffraction Fourier fingerprint pattern technique].  

PubMed

The powder X-ray diffraction Fourier fingerprint pattern technique was used to develop a new quantitation method for the analysis of andrographolide and dehydroandrographolide. And the high performance liquid chromatography method was used to evaluate the quantity of andrographolide and dehydroandrographolide. The relationship of diffraction peak intensity and content of andrographolide and dehydroandrographolide was investigated. The powder X-ray diffraction Fourier fingerprint pattern analysis technique can be used to evaluate the quantity of andrographolide and dehydroandrographolide in the herb simultaneously. PMID:20931774

Gong, Ning-Bo; L, Li-Juan; Liu, Chao; Ma, Lin; Chen, Ruo-Yun; L, Yang

2010-05-01

24

A review of the hybrid techniques for the fabrication of hard magnetic microactuators based on bonded magnetic powders  

NASA Astrophysics Data System (ADS)

Polymer composites based on permanent magnetic bonded powders exhibit immense potential for applications in microactuators and sensors with magnetic performances comparable to their fully dense counterparts. While fabrication and integration of magnetic devices based on bonded magnetic powders is challenging via conventional deposition and electrochemical growth techniques, hybrid fabrication offers a promising alternative. This paper presents the evolution of permanent magnetic materials into bonded magnetic powders, the magnetic performance figures of merit of permanent magnetic materials significant for the design and manufacture of polymer based sensors and actuators. A review of the hybrid fabrication techniques such as replica molding, squeegee coating, spin casting etc are reported. Critical factors affecting the fabrication of polymer magnetic composites such as filler particle size and effect of magnetic field during fabrication are discussed. Prior art based on polymer magnetic composites for the fabrication of hard magnetic films and hard magnetic actuators are presented.

Pallapa, M.; Yeow, J. T. W.

2015-02-01

25

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

NASA Astrophysics Data System (ADS)

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

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

26

Investigation of photoconductivity in Pr-doped ZnS powder prepared by simple heat treatment technique  

NASA Astrophysics Data System (ADS)

In the present work, we have investigated photoconductivity properties in Pr-doped ZnS powders. ZnS: Pr powder has been prepared by simple heat treatment technique at temperature of 800 癈. I-V characteristics i.e. voltage dependence of photocurrent under UV illumination (?=365 nm) exhibits non-Ohmic (r < 1) behavior at low as well as high voltage regimes. The crystallite size of ZnS:Pr corresponding to main XRD peak is estimated as 37.25 ?m. The micro strain is calculated as 0.46.

Srivastava, Rajneesh K.; Srivastava, Smriti; Mishra, Sheo K.; Shukla, R. K.

2014-04-01

27

Growth and characterization of organometallic L-alanine cadmium chloride single crystal by slow evaporation technique  

NASA Astrophysics Data System (ADS)

Single crystals of L-alanine cadmium chloride (LACC), an organometallic nonlinear optical material, have been grown by the slow evaporation technique. The grown crystals were subjected to various characterization techniques, such as single crystal and powder XRD, FTIR, UV-vis and TGA-DTA. The mechanical properties of the crystals show that this material belongs to the category of hard materials. Second harmonic generation was confirmed by the Kurtz and Perry powder technique. Electrical parameters, such as dielectric constant, dielectric loss, ac and dc conductivity and their corresponding activation energies have been studied. The low dielectric constant and dielectric loss suggest that this material is a good candidate for micro-electronic applications.

Bright, K. C.; Freeda, T. H.

2010-09-01

28

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

Microsoft Academic Search

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

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

2002-01-01

29

Nanospray Drying as a Novel Technique for the Manufacturing of Inhalable NSAID Powders  

PubMed Central

The aim of this research was to evaluate the potential of the nanospray drier as a novel apparatus for the manufacturing of a dry powder for inhalation containing ketoprofen lysinate, a nonsteroidal anti-inflammatory drug able to control the inflammation in cystic fibrosis patients. We produced several ketoprofen lysinate and leucine powder batches by means of nanospray dryer, studying the influence of process parameters on yield, particle properties (size distribution and morphology), and, mainly, aerodynamic properties of powders. Micronized particles were prepared from different hydroalcoholic solutions (alcohol content from 0 to 30% v/v) using ketoprofen in its lysine salt form and leucine as dispersibility enhancer in different ratios (from 5 to 15% w/w) with a total solid concentration ranging from 1 to 7% w/v. Results indicated that the spray head equipped with a 7?祄 nozzle produced powders too big to be inhaled. The reduction of nozzle size from 7 to 4?祄 led to smaller particles suitable for inhalation but, at the same time, caused a dramatic increase in process time. The selection of process variables, together with the nozzle pretreatment with a surfactant solution, allowed us to obtain a free flowing powder with satisfying aerosol performance, confirming the usefulness of the nanospray drier in the production of powder for inhalation. PMID:25580462

Rita Patrizia, Aquino; Mariateresa, Stigliani; Pasquale, Del Gaudio; Teresa, Mencherini; Francesca, Sansone; Paola, Russo

2014-01-01

30

Nanospray Drying as a Novel Technique for the Manufacturing of Inhalable NSAID Powders.  

PubMed

The aim of this research was to evaluate the potential of the nanospray drier as a novel apparatus for the manufacturing of a dry powder for inhalation containing ketoprofen lysinate, a nonsteroidal anti-inflammatory drug able to control the inflammation in cystic fibrosis patients. We produced several ketoprofen lysinate and leucine powder batches by means of nanospray dryer, studying the influence of process parameters on yield, particle properties (size distribution and morphology), and, mainly, aerodynamic properties of powders. Micronized particles were prepared from different hydroalcoholic solutions (alcohol content from 0 to 30% v/v) using ketoprofen in its lysine salt form and leucine as dispersibility enhancer in different ratios (from 5 to 15% w/w) with a total solid concentration ranging from 1 to 7% w/v. Results indicated that the spray head equipped with a 7?祄 nozzle produced powders too big to be inhaled. The reduction of nozzle size from 7 to 4?祄 led to smaller particles suitable for inhalation but, at the same time, caused a dramatic increase in process time. The selection of process variables, together with the nozzle pretreatment with a surfactant solution, allowed us to obtain a free flowing powder with satisfying aerosol performance, confirming the usefulness of the nanospray drier in the production of powder for inhalation. PMID:25580462

Rita Patrizia, Aquino; Mariateresa, Stigliani; Pasquale, Del Gaudio; Teresa, Mencherini; Francesca, Sansone; Paola, Russo

2014-01-01

31

Printability of calcium phosphate: calcium sulfate powders for the application of tissue engineered bone scaffolds using the 3D printing technique.  

PubMed

In this study, calcium phosphate (CaP) powders were blended with a three-dimensional printing (3DP) calcium sulfate (CaSO4)-based powder and the resulting composite powders were printed with a water-based binder using the 3DP technology. Application of a water-based binder ensured the manufacture of CaP:CaSO4 constructs on a reliable and repeatable basis, without long term damage of the printhead. Printability of CaP:CaSO4 powders was quantitatively assessed by investigating the key 3DP process parameters, i.e. in-process powder bed packing, drop penetration behavior and the quality of printed solid constructs. Effects of particle size, CaP:CaSO4 ratio and CaP powder type on the 3DP process were considered. The drop penetration technique was used to reliably identify powder formulations that could be potentially used for the application of tissue engineered bone scaffolds using the 3DP technique. Significant improvements (p<0.05) in the 3DP process parameters were found for CaP (30-110 ?m):CaSO4 powders compared to CaP (<20 ?m):CaSO4 powders. Higher compressive strength was obtained for the powders with the higher CaP:CaSO4 ratio. Hydroxyapatite (HA):CaSO4 powders showed better results than beta-tricalcium phosphate (?-TCP):CaSO4 powders. Solid and porous constructs were manufactured using the 3DP technique from the optimized CaP:CaSO4 powder formulations. High-quality printed constructs were manufactured, which exhibited appropriate green compressive strength and a high level of printing accuracy. PMID:24656346

Zhou, Zuoxin; Buchanan, Fraser; Mitchell, Christina; Dunne, Nicholas

2014-05-01

32

Capreomycin inhalable powders prepared with an innovative spray-drying technique.  

PubMed

The aim of the work was to produce inhalable capreomycin powders using a novel spray-drying technology. A 2(3) factorial design was used to individuate the best working conditions. The maximum desirability was identified at the smallest mean volume diameter (dv) and span, and the highest yield. Powders were characterized for size, morphology, flowability and aerodynamic properties. Mathematical models showed a good predictivity with biases lower than 20%. The maximum conformity with desirability criteria was obtained spraying a 10mg/mL bacitracin solution at 111 癈 with the 4 ?m pore size membrane. By processing capreomycin sulfate with the parameters optimized for bacitracin, an inhalable powder was obtained (i.e., yield of 82%, dv of 3.83 ?m, and span of 1.04). By further optimization, capreomycin sulfate powder characteristics were improved (i.e., yield, ?71%; dv, 3.25 ?m; span, 0.95). After formulation with lactose, emitted dose and respirable fraction of 87% and ?27% were obtained, respectively. Two capreomycin sulfate powders with suitable properties for inhalation were produced using the nano spray-dryer B-90. PMID:24747443

Schoubben, Aur閘ie; Giovagnoli, Stefano; Tiralti, Maria Cristina; Blasi, Paolo; Ricci, Maurizio

2014-07-20

33

Electrical CT image reconstruction technique for powder flow in petroleum refinery process  

NASA Astrophysics Data System (ADS)

A new reconstruction method called sampled pattern matching (SPM) was applied to the image reconstruction of an electrical capacitance computed tomography in powder flow in a vertical pipe for petroleum refinery process. This new method is able to achieve stable convergence without the use of an empirical value. Experiments were carried out using fluid catalytic cracking (FCC) catalysts as powder with two air volume flow rates and four powder volume flow rates to measure the capacitance of a pipe cross section. The SPM method is compared with conventional methods in terms of volume fraction, residual capacitance, and correlation capacitance. Overall, the SPM method proved superior to conventional methods without any empirical value because SPM achieves accurate reconstruction by using an objective function that is calculated as the inner product calculation between the experimental capacitance and the reconstructed image capacitance.

Takei, Masahiro; Doh, Deog-Hee; Ochi, Mitsuaki

2008-03-01

34

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

SciTech Connect

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

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

1996-12-31

35

Laser welding of copper with stellite 6 powder and investigation using LIBS technique  

NASA Astrophysics Data System (ADS)

This paper reports a process by which two copper plates are welded together by using a millisecond pulse Nd:YAG laser with the addition of stellite 6 powder which increases the absorption of laser energy. It also reports an interesting application of Laser Induced Breakdown Spectroscopy (LIBS) in order to determine the elemental composition and diffusion of stellite 6 powder into the copper plates. The effects of laser peak power and pulse duration are examined to optimize the welding. The amount of stellite 6 powder is also optimized for a high quality welding. The tensile strength and hardness values are measured for different laser parameters. The EDX and SEM results show that the stellite 6 powder particles penetrate into the copper plates and increase the hardness. The elements in laser weld joints of copper plates were analyzed with LIBS, utilizing a high resolution multi-channel CCD spectrometer and a nanosecond pulse Nd:YAG laser, providing a depth profile of elemental composition of the penetrated region.

Genc Oztoprak, B.; Akman, E.; Hanon, M. M.; G黱es, M.; G黰黶, S.; Kacar, E.; Gundogdu, O.; Zeren, M.; Demir, A.

2013-02-01

36

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

Microsoft Academic Search

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

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

1994-01-01

37

Unraveling the nature of electric field- and stress- induced structural transformations in soft PZT by a new powder poling technique.  

PubMed

A 'powder-poling' technique was developed to study electric field induced structural transformations in ferroelectrics exhibiting a morphotropic phase boundary (MPB). The technique was employed on soft PZT exhibiting a large longitudinal piezoelectric response (d33?650爌C燦(-1)). It was found that electric poling brings about a considerable degree of irreversible tetragonal to monoclinic transformation. The same transformation was achieved after subjecting the specimen to mechanical stress, which suggests an equivalence of stress and electric field with regard to the structural mechanism in MPB compositions. The electric field induced structural transformation was also found to be accompanied by a decrease in the spatial coherence of polarization. PMID:25629264

Kalyani, Ajay Kumar; V, Lalitha K; James, Ajit R; Fitch, Andy; Ranjan, Rajeev

2015-02-25

38

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

39

Preparation of Cu and Fly Ash Composite by Powder Metallurgy Technique  

SciTech Connect

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

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

2011-03-30

40

Preparation of Cu and Fly Ash Composite by Powder Metallurgy Technique  

NASA Astrophysics Data System (ADS)

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

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

2011-03-01

41

Preparation of redispersible liposomal dry powder using an ultrasonic spray freeze-drying technique for transdermal delivery of human epithelial growth factor  

PubMed Central

In this work, an ultrasonic spray freeze-drying (USFD) technique was used to prepare a stable liposomal dry powder for transdermal delivery of recombinant human epithelial growth factor (rhEGF). Morphology, particle size, entrapment efficiency, in vitro release, and skin permeability were systematically compared between rhEGF liposomal dry powder prepared using USFD and that prepared using a conventional lyophilization process. Porous and spherical particles with high specific area were produced under USFD conditions. USFD effectively avoided formation of ice crystals, disruption of the bilayer structure, and drug leakage during the liposome drying process, and maintained the stability of the rhEGF liposomal formulation during storage. The reconstituted rhEGF liposomes prepared from USFD powder did not show significant changes in morphology, particle size, entrapment efficiency, or in vitro release characteristics compared with those of rhEGF liposomes before drying. Moreover, the rhEGF liposomal powder prepared with USFD exhibited excellent enhanced penetration in ex vivo mouse skin compared with that for powder prepared via conventional lyophilization. The results suggest that ultrasonic USFD is a promising technique for the production of stable protein-loaded liposomal dry powder for application to the skin. PMID:24729702

Yin, Fei; Guo, Shiyan; Gan, Yong; Zhang, Xinxin

2014-01-01

42

Comparison of powder produced by evaporative precipitation into aqueous solution (EPAS) and spray freezing into liquid (SFL) technologies using novel Z-contrast STEM and complimentary techniques.  

PubMed

The objective of this study was to compare the properties of particles formed by nucleation and polymer stabilization (e.g. evaporative precipitation into aqueous solution (EPAS)) versus rapid freezing (e.g. spray freezing into liquid (SFL)). Powders formed by EPAS and SFL, composed of danazol and PVP K-15 in a 1:1 ratio, were characterized using X-ray powder diffraction, modulated differential scanning calorimetry (MDSC), contact angle determination, dissolution, scanning electron microscopy (SEM), environmental scanning electron microscopy (ESEM), BET specific surface area, and Z-contrast scanning transmission electron microscopy (STEM). Large differences in particle morphologies and properties were observed and explained in terms of the particle formation mechanisms. Both techniques produced amorphous powders with high T(g) and low contact angle values. However, STEM analysis showed highly porous bicontinuous nanostructured 30nm particles connected by narrow bridges for SFL versus aggregated 500 nm primary particles for EPAS. The combination of STEM and other characterization techniques indicates solid solutions were formed for the SFL powders consistent with rapid freezing. In contrast, the EPAS particle cores are enriched in hydrophobic API and the outer surface is enriched in the hydrophilic polymer, with less miscibility than in the SFL powders. Consequently, dissolution rates are faster for the SFL particles, although both techniques enhanced dissolution rates of the API. PMID:15848060

Vaughn, Jason M; Gao, Xiaoxia; Yacaman, Miguel-Jose; Johnston, Keith P; Williams, Robert O

2005-05-01

43

Application of ultrasound irradiation on sol-gel technique for corrosion protection of Al65Cu20Fe15 alloy powder  

NASA Astrophysics Data System (ADS)

Al65Cu20Fe15 alloy powder was firstly encapsulated by the conventional sol-gel technique utilizing tetraethoxysilane (TEOS) as the precursor in order to improve its corrosion resistance. The optimization was based on nine well-planned orthogonal experiments (L9 (34)). Four main factors in the encapsulation process (i.e. reaction temperature, ethylenediamine concentration, TEOS concentration and feeding method) were investigated. According to the visual analyses of the result, the optimum condition was obtained. Based on the optimal condition in the conventional sol-gel technique, the encapsulation process was then conducted under ultrasonic irradiation. The effects of ultrasound amplitude and irradiation time on the encapsulation process were also studied. FTIR, XRD, SEM, DLS and EDS were also used to characterize the resulting sample. Finally, the corrosion inhibition efficiency of encapsulated powder attained 99.3% in the acidic condition of pH 1, and the average grain size (d50) of the encapsulated powder was just 4.8% larger than that of the raw powder, implying that there was a thin silica film on the surface of powder.

Liang, Bo; Zhang, Baoyan; Wang, Guodong; Li, Di; Zhang, Xiaoming

2013-11-01

44

High temperature 3-D thermoluminescence spectra of Eu 3+ activated YVO 4 YPO 4 powder systems reacted by hydrolyzed colloid reaction (HCR) technique  

Microsoft Academic Search

Three-dimensional (3-D) thermoluminescence (TL) spectra of Eu3+:YVO4, Eu3+:YV0.4P0.6O4andEu3+:Ce:YPO4 powders irradiated by X-rays were studied in the temperature range 30350 癈. The powders were reacted by a special hydrolyzed colloid reaction (HCR) technique at ~ 80 癈 and were subsequently fired at 800 癈. The glow curves possess two major peaks indicating different defect structures. The first TL peak was observed

S. Erdei; L. Kov醕s; M. Martini; F. Meinardi; F. W. Ainger; W. B. White

1996-01-01

45

Enhancement of aged and denatured fingerprints using the cyanoacrylate fuming technique following dusting with amino acid-containing powders.  

PubMed

We have carried out experiments to investigate the aging of latent fingerprints deposited on black PVC over a period of 4-15 weeks. A thumbprint was used in each case and before deposition of the print the donor rubbed their thumb around their nose to add sebaceous deposits. We have studied the effect of heat, light, and moisture and we find that moisture is the most significant factor in the degradation of the latent print. We have attempted to enhance these latent prints by dusting with valine powder or powders composed of valine mixed with gold or red fluorescent commercial fingerprint powders. To make a direct comparison between "treated" and "untreated" prints, the prints were cut in half with one-half being "treated" and one-half not. Our studies show the best results being obtained when powders of valine and red fluorescent powders are applied prior to cyanoacrylate fuming. PMID:23316682

Nixon, Carly; Almond, Matthew J; Baum, John V; Bond, John W

2013-03-01

46

Improved L-C resonant decay technique for Q measurement of quasilinear power inductors: New results for MPP and ferrite powdered cores  

NASA Technical Reports Server (NTRS)

The L-C resonant decay technique for measuring circuit Q or losses is improved by eliminating the switch from the inductor-capacitor loop. A MOSFET switch is used instead to momentarily connect the resonant circuit to an existing voltage source, which itself is gated off during the decay transient. Very reproducible, low duty cycle data could be taken this way over a dynamic voltage range of at least 10:1. Circuit Q is computed from a polynomial fit to the sequence of the decaying voltage maxima. This method was applied to measure the losses at 60 kHz in inductors having loose powder cores of moly permalloy and an Mn-Zn power ferrite. After the copper and capacitor losses are separated out, the resulting specific core loss is shown to be roughly as expected for the MPP powder, but anomalously high for the ferrite powder. Possible causes are mentioned.

Niedra, Janis M.; Gerber, Scott S.

1995-01-01

47

Investigation of the Surface Stress in SiC and Diamond Nanocrystals by In-situ High Pressure Powder Diffraction Technique  

NASA Technical Reports Server (NTRS)

The real atomic structure of nanocrystals determines key properties of the materials. For such materials the serious experimental problem lies in obtaining sufficiently accurate measurements of the structural parameters of the crystals, since very small crystals constitute rather a two-phase than a uniform crystallographic phase system. As a result, elastic properties of nanograins may be expected to reflect a dual nature of their structure, with a corresponding set of different elastic property parameters. We studied those properties by in-situ high-pressure powder diffraction technique. For nanocrystalline, even one-phase materials such measurements are particularly difficult to make since determination of the lattice parameters of very small crystals presents a challenge due to inherent limitations of standard elaboration of powder diffractograms. In this investigation we used our methodology of the structural analysis, the 'apparent lattice parameter' (alp) concept. The methodology allowed us to avoid the traps (if applied to nanocrystals) of standard powder diffraction evaluation techniques. The experiments were performed for nanocrystalline Sic and GaN powders using synchrotron sources. We applied both hydrostatic and isostatic pressures in the range of up to 40 GPa. Elastic properties of the samples were examined based on the measurements of a change of the lattice parameters with pressure. The results show a dual nature of the mechanical properties (compressibilities) of the materials, indicating a complex, core-shell structure of the grains.

Palosz, B.; Stelmakh, S.; Grzanka, E.; Gierlotka, S.; Zhao, Y.; Palosz, W.

2003-01-01

48

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

Microsoft Academic Search

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

S Gorsse; J. P Chaminade; Y Le Petitcorps

1998-01-01

49

Synthesis and characterization of LiMn 2O 4 powders by the combustion-assisted sol杇el technique  

Microsoft Academic Search

LiMn2O4 powders were prepared by heating the ignited LiMn2O4 precursor gel using lithium acetate, manganese acetate, citric acid and glycol as starting materials. The influence of synthesis conditions on the structural and electrochemical properties of LiMn2O4 was investigated by X-ray diffraction, scanning electron microscopy and charge杁ischarge experiments. The powders prepared under different conditions are of good crystallinity. The particle size,

Xian Ming Wu; Xin Hai Li; Zhuo Bing Xiao; Jianben Liu; Wen Bin Yan; Ming You Ma

2004-01-01

50

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

Microsoft Academic Search

In the present study, an extended release pellet dosage form of ketoprofen was prepared using powder layering technique. A\\u000a combination of ethyl cellulose (45 cps) and shellac polymers was used as a binder (12% w\\/w polymer) during drug layering and\\u000a an extended release coating (1:3 ratio at 2%, 4% and 7% w\\/w polymer) within the same apparatus. The coated pellets

Raveendra Pai; Kanchan Kohli; Gaurav Jain; Birendra Srivastava

2011-01-01

51

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

52

Surface Corrosion of Ti16Si4B Powder Alloy Implanted With Nitrogen by Plasma-Based Technique  

Microsoft Academic Search

Titanium materials with a new ternary phase, Ti6Si2B, can be manufactured by high-energy ball milling and further sintering of titanium, silicon, and boron powders. In this paper, hot pressing was chosen to compact the granules and then prevent high porosity and grain coarsening during sintering. Sub- sequently, the surface of the Ti-16Si-4B (at.%) alloy was modified by nitrogen ion implantation

Bruno Bacci Fernandes; Mario Ueda; Graziela da Silva Savonov; Carlos de Moura Neto; Alfeu Saraiva Ramos

2011-01-01

53

The development and evaluation of an alternative powder prepregging technique for use with LaRC-TPI/graphite composites  

NASA Technical Reports Server (NTRS)

An alternative powder prepregging method for use with LaRC-TPI (a thermoplastic polyimide)/graphite composites is investigated. The alternative method incorporates the idea of moistening the fiber prior to powder coating. Details of the processing parameters are given and discussed. The material was subsequently laminated into small coupons which were evaluated for processing defects using electron microscopy. After the initial evaluation of the material, no major processing defects were encountered but there appeared to be an interfacial adhesion problem. As a result, prepregging efforts were extended to include an additional fiber system, XAS, and a semicrystalline form of the matrix. The semicrystalline form of the matrix was the result of a complex heat treating cycle. Using scanning electron microscopy (SEM), the fiber/matrix adhesion was evaluated in these systems relative to the amorphous/XAS coupons. Based on these results, amorphous and semicrystalline/AS-4 and XAS materials were prepregged and laminated for transverse tensile testing. The results of these tests are presented, and in an effort to obtain more information on the effect of the matrix, remaining semicrystalline transverse tensile coupons were transformed back to the amorphous state and tested. The mechanical properties of the transformed coupons returned to the values observed for the original amorphous coupons, and the interfacial adhesion, as observed by SEM, was better than in any previous sample.

Ogden, Andrea L.; Hyer, Michael W.; Wilkes, Garth L.; Loos, Alfred C.; St.clair, Terry L.

1991-01-01

54

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

PubMed

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

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

2003-01-01

55

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

56

Mystery Powders  

NSDL National Science Digital Library

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

American Chemical Society

2000-01-01

57

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.

58

Differential Proteins of Panax Notoginseng Powder Inducement Identified and Analyzed with Proteomic Techniques in Neural Connective of Aplysia  

Microsoft Academic Search

Extract of Panax notoginseng (PNE) was separated and its saponins component containing Rb1, Rg1, Re, R1 was further identified by RP-HPLC approach synchronously. Using an analytical model of aplysia (Notarchus leachii cirrosus Stimpson, NLCS) and a revulsant of Panax notoginseng, differential proteins of neural connective between control aplysia and experimental ones were revealed by proteomic techniques in NLCS. Whole proteins

Li-Jian FENG; Lin HUANG; Hui-Qin ZHUO; He-Qing HUANG

2008-01-01

59

Shear consolidation of powders  

NASA Astrophysics Data System (ADS)

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

Hanna, James A.

60

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 (Pm3痭) is well described by dynamical disorder among the cation sites and also between opposite framework "partial collapse" angles.

Campbell, Branton J.

61

Investigation on the growth and characterization of nonlinear optical single crystal 4,4'-dimethoxybenzoin by vertical Bridgman technique  

NASA Astrophysics Data System (ADS)

An organic nonlinear optical (NLO) material 4,4'-dimethoxybenzoin single crystal has been grown by vertical Bridgman technique using single wall ampoule. The grown crystal was confirmed by single crystal and powder X-ray diffraction (XRD) analyses. The functional groups of the grown crystal were identified by Fourier transform infra red analysis. The thermal behavior of the grown crystal were studied by thermo gravimetric (TG) and differential scanning calorimetric (DSC) analysis. The UV-vis-NIR spectrum has been recorded in the range 190-1100 nm and it shows that the cutoff wavelength of grown crystal is around 343 nm. The yellow emission of the grown crystal was identified by photoluminescence (PL) spectral measurements. The NLO property of the grown crystal was confirmed by Kurtz and Perry powder technique and the SHG efficiency of the grown crystal was found to be 2 times greater than KDP. The dielectric measurements were carried out and the results indicate that an increase in dielectric parameters with increase of temperature at all frequencies.

Arivazhagan, T.; Rajesh, Narayana Perumal

2014-12-01

62

Rapid analysis of adulterations in Chinese lotus root powder (LRP) by near-infrared (NIR) spectroscopy coupled with chemometric class modeling techniques.  

PubMed

This paper develops a rapid analysis method for adulteration identification of a popular traditional Chinese food, lotus root powder (LRP), by near-infrared spectroscopy and chemometrics. 85 pure LRP samples were collected from 7 main lotus producing areas of China to include most if not all of the significant variations likely to be encountered in unknown authentic materials. To evaluate the model specificity, 80 adulterated LRP samples prepared by blending pure LRP with different levels of four cheaper and commonly used starches were measured and predicted. For multivariate quality models, two class modeling methods, the traditional soft independent modeling of class analogy (SIMCA) and a recently proposed partial least squares class model (PLSCM) were used. Different data preprocessing techniques, including smoothing, taking derivative and standard normal variate (SNV) transformation were used to improve the classification performance. The results indicate that smoothing, taking second-order derivatives and SNV can improve the class models by enhancing signal-to-noise ratio, reducing baseline and background shifts. The most accurate and stable models were obtained with SNV spectra for both SIMCA (sensitivity 0.909 and specificity 0.938) and PLSCM (sensitivity 0.909 and specificity 0.925). Moreover, both SIMCA and PLSCM could detect LRP samples mixed with 5% (w/w) or more other cheaper starches, including cassava, sweet potato, potato and maize starches. Although it is difficult to perform an exhaustive collection of all pure LRP samples and possible adulterations, NIR spectrometry combined with class modeling techniques provides a reliable and effective method to detect most of the current LRP adulterations in Chinese market. PMID:23870978

Xu, Lu; Shi, Peng-Tao; Ye, Zi-Hong; Yan, Si-Min; Yu, Xiao-Ping

2013-12-01

63

Energetic powder  

DOEpatents

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

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

2003-12-23

64

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

65

The Density Structure of Highly Compact H ii Regions Jos'e Franco 1 , Stan Kurtz 1 , Peter Hofner 2 , Leonardo Testi 3 , Guillermo Garc'iaSegura 1 and  

E-print Network

The Density Structure of Highly Compact H ii Regions Jos'e Franco 1 , Stan Kurtz 1 , Peter Hofner 2 5, I颅50125 Firenze, Italy #12; -- 2 -- ABSTRACT We report the density structure of the ultracompact H ii (UC Hii) regions G35.20\\Gamma1.74, G9.62+0.19颅E, and G75.78+0.34颅H 2 O. The density profiles

Testi, Leonardo

66

Exploring Baking Powder  

NSDL National Science Digital Library

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

Kessler, James H.; Galvan, Patricia M.

2007-01-01

67

Powder treatment process  

DOEpatents

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

Weyand, John D. (Greensburg, PA)

1988-01-01

68

Powder treatment process  

DOEpatents

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

Weyand, J.D.

1988-02-09

69

Powder handling for automated fuel processing  

SciTech Connect

Installation of the Secure Automated Fabrication (SAF) line has been completed. It is located in the Fuel Cycle Plant (FCP) at the Department of Energy's (DOE) Hanford site near Richland, Washington. The SAF line was designed to fabricate advanced reactor fuel pellets and assemble fuel pins by automated, remote operation. This paper describes powder handling equipment and techniques utilized for automated powder processing and powder conditioning systems in this line. 9 figs.

Frederickson, J.R.; Eschenbaum, R.C.; Goldmann, L.H.

1989-04-09

70

Assessment of diversity among populations of Rauvolfia serpentina Benth. Ex. Kurtz. from Southern Western Ghats of India, based on chemical profiling, horticultural traits and RAPD analysis.  

PubMed

Genetic, morphological and chemical variations of ten natural populations of Rauvolfia serpentina Benth. Ex. Kurtz. from Southern Western Ghats of India were assessed using RAPD markers reserpine content and morphological traits. An estimate of genetic diversity and differentiation between genotypes of breeding germplasm is of key importance for its improvement. Populations were collected from different geographical regions. Data obtained through three different methods were compared and the correlation among them was estimated. Statistical analysis showed significant differences for all horticultural characteristics among the accessions suggesting that selection for relevant characteristics could be possible. Variation in the content of Reserpine ranges from 0.192 g/100 g (population from Tusharagiri) to 1.312 g/100 g (population from Aryankavu). A high diversity within population and high genetic differentiation among them based on RAPDs were revealed caused both by habitat fragmentation of the low size of most populations and the low level of gene flow among them. The UPGMA dendrogram and PCA analysis based on reserpine content yielded higher separation among populations indicated specific adaptation of populations into clusters each of them including populations closed to their geographical origin. Genetic, chemical and morphological data were correlated based on Mantel test. Given the high differentiation among populations conservation strategies should take into account genetic diversity and chemical variation levels in relation to bioclimatic and geographic location of populations. Our results also indicate that RAPD approach along with horticultural analysis seemed to be best suited for assessing with high accuracy the genetic relationships among distinct R. serpentina accessions. PMID:24096162

Nair, Vadakkemuriyil Divya; Raj, Rajan Pillai Dinesh; Panneerselvam, Rajaram; Gopi, Ragupathi

2014-01-01

71

Resin-Powder Dispenser  

NASA Technical Reports Server (NTRS)

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

Standfield, Clarence E.

1994-01-01

72

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

73

Parametric Powder Diffraction  

NASA Astrophysics Data System (ADS)

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

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

74

Composite powder particles  

NASA Technical Reports Server (NTRS)

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

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

2009-01-01

75

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

76

Gelcasting superalloy powders  

Microsoft Academic Search

Gelcasting is a process for forming inorganic powders into complex shapes. It was originally developed for ceramic powders. A slurry of powder and a monomer solution is poured in to mold and polymerized in-situ to form gelled parts. Typically, only 2-4 wt % Polymer is used. The process has both aqueous and nonaqueous versions. Gelcasting is a generic process and

Janney

1995-01-01

77

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

78

Multiple feed powder splitter  

DOEpatents

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

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

2001-01-01

79

Multiple feed powder splitter  

DOEpatents

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

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

2002-01-01

80

PRESSURELESS SINTERED BERYLLIUM POWDER  

Microsoft Academic Search

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

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

1959-01-01

81

Sintering titanium powders  

SciTech Connect

Recently, there has been renewed interest in low-cost titanium. Near-net-shape powder metallurgy offers the potential of manufacturing titanium articles without costly and difficult forming and machining operations; hence, processing methods such as conventional press-and-sinter, powder forging and powder injection molding are of interest. The sintering behavior of a variety of commercial and experimental titanium powders was studied. Commercial powders were acquired that were produced different routes: (i) sponge fines from the primary titanium processing; (ii) via the hydride-dehydride process; and (iii) gas atomization. The influence of vacuum sintering time (0.5 to 32 hrs) and temperature (1200, 1275 or 1350癈) 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

82

Compaction of Titanium Powders  

SciTech Connect

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

Gerdemann, Stephen,J; Jablonski, Paul, J

2011-05-01

83

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

84

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

85

POWDER COAT APPLICATIONS  

EPA Science Inventory

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

86

Mystery Powder Investigation  

NSDL National Science Digital Library

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

Rachel HallettNjuguna

2012-07-27

87

Gelcasting superalloy powders  

SciTech Connect

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

Janney, M.A.

1995-12-31

88

Hafnium powder production processes  

NASA Astrophysics Data System (ADS)

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

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

2010-09-01

89

Method for classifying ceramic powder  

NASA Technical Reports Server (NTRS)

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

Takabe, K.

1983-01-01

90

Strength enhancement process for prealloyed powder superalloys  

NASA Technical Reports Server (NTRS)

A technique involving superplastic processing and high pressure autoclaving was applied to a nickel base prealloyed powder alloy. Tensile strengths as high as 2865 MN/sq m at 480 C were obtained with as-superplastically deformed material. Appropriate treatments yielding materials with high temperature tensile and stress rupture strengths were also devised.

Waters, W. J.; Freche, J. C.

1977-01-01

91

Ceramic powder synthesis by spray pyrolysis  

Microsoft Academic Search

A variety of spray pyrolysis (SP) techniques have been developed to directly produce ceramic powders from solutions. This paper reviews the current status of these processes in terms of the process parameters that enable the formation of particles with controlled morphology and composition. A model incorporating solute diffusion in the droplet and solvent evaporation from the droplet surface is presented

Gary L. Messing; Shi-Chang Zhang; Gopal V. Jayanthi

1993-01-01

92

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

93

Determination of porosity variations in powder beds.  

PubMed

A gamma-ray attenuation technique for detecting local porosity variations in packings of pharmaceutical powders has been developed and assessed. It proved necessary to employ an empirical expression describing the attenuation coefficient of the model material, lactose, as a function of porosity. The precision of measurement of local porosity can be pre-selected due to the statistical basis of the method, and local porosity measurements with 95% confidence intervals of +/- 0.005 can readily be carried out. A method of producing grey-scale images of porosity distributions has been employed to enable the degree of inhomogeneity of a powder bed to be seen. PMID:6124616

Woodhead, P J; Hardy, J G; Newton, J M

1982-06-01

94

Whole powder pattern modelling.  

PubMed

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

Scardi, P; Leoni, M

2002-03-01

95

Iowa Powder Atomization Technologies  

SciTech Connect

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

None

2012-01-01

96

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

2013-12-01

97

Dynamic compaction of tungsten carbide powder.  

SciTech Connect

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

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

2005-04-01

98

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

99

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

Microsoft Academic Search

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

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

1970-01-01

100

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

Microsoft Academic Search

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

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

2006-01-01

101

Sintering of Ultrafine Metal Powders. I. Coalescence Growth Stage of Au and Ag  

Microsoft Academic Search

Sintering of ultrafine powders of Au and Ag, produced by a gas evaporation technique, has been studied by the electron microscopy and X-ray diffraction methods. The critical temperature, above which the particle size increases, is found to be room temperature for Au powders and 60癈 for Ag powders with a particle size of about 200 . Retardation of sintering is

Saburo Iwama; Toshio Sahashi

1980-01-01

102

Spheroidization of glass powders for glass ionomer cements.  

PubMed

Commercial angular glass powders were spheroidized using both the flame spraying and inductively coupled radio frequency plasma spraying techniques. Spherical powders with different particle size distributions were obtained after spheroidization. The effects of spherical glass powders on the mechanical properties of glass ionomer cements (GICs) were investigated. Results showed that the particle size distribution of the glass powders had a significant influence on the mechanical properties of GICs. Powders with a bimodal particle size distribution ensured a high packing density of glass ionomer cements, giving relatively high mechanical properties of GICs. GICs prepared by flame-spheroidized powders showed low strength values due to the loss of fine particles during flame spraying, leading to a low packing density and few metal ions reacting with polyacrylic acid to form cross-linking. GICs prepared by the nano-sized powders showed low strength because of the low bulk density of the nano-sized powders and hence low powder/liquid ratio of GICs. PMID:15046893

Gu, Y W; Yap, A U J; Cheang, P; Kumar, R

2004-08-01

103

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

104

Method for synthesizing powder materials  

DOEpatents

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

Buss, R.J.; Ho, P.

1988-01-21

105

Study of Velocity and Materials on Tribocharging of Polymer Powders for Powder Coating Applications  

NASA Technical Reports Server (NTRS)

Electrostatic powder deposition is widely used in a plethora of industrial-applications ranging from the pharmaceutical and food.industries, to farm equipment and automotive applications. The disadvantages of this technique are possible back corona (pin-like formations) onset and the Faraday penetration limitation (when the powder does not penetrate in some recessed areas). A possible solution to overcome these problems is to use tribochargers to electrostatically charge the powder. Tribocharging, or contact charging while two materials are in contact, is related to the work function difference between the contacting materials and generates bipolarly charged particles. The generation of an ion-free powder cloud by tribocharging with high bipolar charge and an overall charge density of almost zero, provides a better coverage of the recessed areas. In this study, acrylic and epoxy powders were fluidized and charged by passing through stainless steel, copper, aluminum, and polycarbonate static mixers, respectively. The particle velocity was varied to determine its effect on the net charge-to-mass ratio (QIM) acquired by the powders. In general, the Q/M increases rapidly when the velocity was increased from 1.5 to 2.5 m/s, remaining almost constant for higher velocities. Charge separation experiments showed bipolar charging for all chargers.

Biris, Alex S.; Trigwell, Steve; Sims, Robert A.; Mazumder, Malay K.

2005-01-01

106

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

2011-11-01

107

Reducing metal alloy powder costs for use in powder bed fusion additive manufacturing: Improving the economics for production  

NASA Astrophysics Data System (ADS)

Titanium and its associated alloys have been used in industry for over 50 years and have become more popular in the recent decades. Titanium has been most successful in areas where the high strength to weight ratio provides an advantage over aluminum and steels. Other advantages of titanium include biocompatibility and corrosion resistance. Electron Beam Melting (EBM) is an additive manufacturing (AM) technology that has been successfully applied in the manufacturing of titanium components for the aerospace and medical industry with equivalent or better mechanical properties as parts fabricated via more traditional casting and machining methods. As the demand for titanium powder continues to increase, the price also increases. Titanium spheroidized powder from different vendors has a price range from 260/kg-450/kg, other spheroidized alloys such as Niobium can cost as high as $1,200/kg. Alternative titanium powders produced from methods such as the Titanium Hydride-Dehydride (HDH) process and the Armstrong Commercially Pure Titanium (CPTi) process can be fabricated at a fraction of the cost of powders fabricated via gas atomization. The alternative powders can be spheroidized and blended. Current sectors in additive manufacturing such as the medical industry are concerned that there will not be enough spherical powder for production and are seeking other powder options. It is believed the EBM technology can use a blend of spherical and angular powder to build fully dense parts with equal mechanical properties to those produced using traditional powders. Some of the challenges with angular and irregular powders are overcoming the poor flow characteristics and the attainment of the same or better packing densities as spherical powders. The goal of this research is to demonstrate the feasibility of utilizing alternative and lower cost powders in the EBM process. As a result, reducing the cost of the raw material to reduce the overall cost of the product produced with AM. Alternative powders can be made by blending or re-spheroidizing HDH and CPTi powders. Machine modifications were performed to allow the testing and manufacturing with these low cost alternative powders. A comparison was made between alternative powders and gas atomized powders. Powders were compared in terms of morphology and at the microstructural level. Flowability of different powder blends was also measured. Finally, a comparison of parts fabricated from the multiple powder blends and gas atomized powder was made. It has been demonstrated that powder blending can produce fully dense parts in the Arcam system by utilizing the double melt technique or HIPing the built pars. The double melt technique increased the density of the sample part and modified the microstructure into finer martensitic grains. The HIP process can make a part fully dense regardless of what percentage of HDH powder blending is used. The HIP process yielded the same microstructure, regardless of the grain structure it started with. This research allows for the reduction of costs using titanium powders in the EBM system, but can also be implemented with more costly elements and alloys using other metal AM technologies. This includes niobium, tantalum, and nickel-based superalloys for use in various industries.

Medina, Fransisco

108

Accuracy in Powder Diffraction IV  

E-print Network

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

Magee, Joseph W.

109

Nanocrystalline ceria powders through citrate-nitrate combustion.  

PubMed

Nanocrystalline ceria powders have been synthesized by combustion technique using citric acid as a fuel and nitrate as an oxidizer. The auto-ignition of the gels containing cerium nitrate and citric acid resulted in ceria powders. A theory based on adiabatic flame temperature for different citric acid-to-cerium nitrate molar ratios has been proposed to explain the nature of combustion reaction and its correlation with the powder characteristics. Specific surface area and primary particle size of the ceria powder obtained through fuel-deficient precursor was found to be approximately = 127 m2/g and 2.5-10 nm, respectively. The combustion synthesized ceria powder when cold pressed and sintered in air at 1250 degrees C for 1 hour resulted in approximately = 96% of its theoretical density with sub-micron grains. PMID:16573097

Purohit, R D; Saha, S; Tyagi, A K

2006-01-01

110

Molten salt synthesis of YAlO3 powders  

NASA Astrophysics Data System (ADS)

In this work, the molten salt synthesis technique was applied to the synthesis of YAlO3 powder using LiCl, NaCl or KCl salt as the flux. YAlO3 powder was synthesized by reacting equimolar amounts of Y2O3 and Al2O3 powders in LiCl salt. The synthesis temperature for YAlO3 using LiCl salt was 1300 癈 which is by about 500 癈 lower than that in the conventional mixed-oxide method. The synthesized powders have been characterized using powder X-ray diffraction (XRD) analysis and field emission scanning electron microscopy (FE-SEM). The effect of the salt type on the formation of YAlO3 has also been investigated.

Lee, Joo-Sin

2013-04-01

111

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

112

An insight into powder entrainment and drug delivery mechanisms from a modified Rotahaler().  

PubMed

This study aims to improve understanding of the powder fluidisation and aerosolisation processes unique to a split capsule dry powder inhaler. It uses a combination of dynamic real-time methods and a suite of powder material physicochemical characterisation methods. The study focused on examining the effect of different characteristics of lactose carrier employed, and considered specifically the powder fluidisation, entrainment and de-agglomeration mechanisms. A GSK Rotahaler() was selected as the inhaler device. Powder fluidisation and entrainment were investigated using the ensemble technique of laser diffraction and high-speed imaging. This ensemble technique afforded both the powder entrainment profile and simultaneous visual confirmation of the capsule movement and powder fluidisation within the Rotahaler. The results showed that powder fluidisation from a dynamic split capsule was substantially different to that from a static powder bed. Furthermore, the presence of the split capsule dominated powder emission mechanisms from the Rotahaler, regulated by its impaction on the grid/Rotahaler wall and the rotational movement in the entrained air. Of all the material characterisation metrics, the most significant linear correlation was revealed between powder permeability and the aerosolisation efficiency as measured by fine particle fraction (R(2)=0.98). This indicates that drug delivery from the Rotahaler was mainly governed by the influence of the cohesive fine particle size component. Powder permeability as a practical test may afford an effective and practical predictive link between the raw excipients and drug delivery performance from the capsule device. PMID:25196720

Sim, Sally; Margo, Kenneth; Parks, Jonathan; Howell, Ruth; Hebbink, Gerald A; Orlando, Laurence; Larson, Ian; Leslie, Philip; Ho, Louise; Morton, David A V

2014-12-30

113

Aluminum-lithium powder metallurgy alloys with improved toughness  

NASA Astrophysics Data System (ADS)

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

Webster, D.

1988-03-01

114

Investigation of Soap Powders  

E-print Network

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

Bragg, G.A.

1913-01-01

115

Sintering of powder mixtures and the growth of ferrous powder metallurgy  

Microsoft Academic Search

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

K. S Narasimhan

2001-01-01

116

Prospects of Nanodispersive Powder Applications in Surface Engineering Technologies  

Microsoft Academic Search

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

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

117

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

118

Carboxymethylation of Tamarind kernel powder  

Microsoft Academic Search

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

Puja Goyal; Vineet Kumar; Pradeep Sharma

2007-01-01

119

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

Code of Federal Regulations, 2011 CFR

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

2011-04-01

120

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

Code of Federal Regulations, 2010 CFR

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

2010-04-01

121

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

Code of Federal Regulations, 2012 CFR

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

2012-04-01

122

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

123

High Resolution Powder Diffraction and Structure Determination  

SciTech Connect

It is clear that high-resolution synchrotrons X-ray powder diffraction is a very powerful and convenient tool for material characterization and structure determination. Most investigations to date have been carried out under ambient conditions and have focused on structure solution and refinement. The application of high-resolution techniques to increasingly complex structures will certainly represent an important part of future studies, and it has been seen how ab initio solution of structures with perhaps 100 atoms in the asymmetric unit is within the realms of possibility. However, the ease with which temperature-dependence measurements can be made combined with improvements in the technology of position-sensitive detectors will undoubtedly stimulate precise in situ structural studies of phase transitions and related phenomena. One challenge in this area will be to develop high-resolution techniques for ultra-high pressure investigations in diamond anvil cells. This will require highly focused beams and very precise collimation in front of the cell down to dimensions of 50 {micro}m or less. Anomalous scattering offers many interesting possibilities as well. As a means of enhancing scattering contrast it has applications not only to the determination of cation distribution in mixed systems such as the superconducting oxides discussed in Section 9.5.3, but also to the location of specific cations in partially occupied sites, such as the extra-framework positions in zeolites, for example. Another possible application is to provide phasing information for ab initio structure solution. Finally, the precise determination of f as a function of energy through an absorption edge can provide useful information about cation oxidation states, particularly in conjunction with XANES data. In contrast to many experiments at a synchrotron facility, powder diffraction is a relatively simple and user-friendly technique, and most of the procedures and software for data analysis are familiar to laboratory diffractionists. This is reflected in the fact that there are already dedicated instruments for powder diffraction at a number of synchrotrons sources, including the NSLS, the Synchrotrons Radiation Source, Daresbury, the Photon Factory, Tsukuba and HASYLAB. In addition, most general purpose beamlines can be adapted for powder diffraction experiments fairly easily. Dedicated beamlines are also planned or under consideration at the next generation of synchrotrons sources, the European Synchrotron Radiation Facility, Grenoble, the Advanced Photon Source, Argonne, and the SPring-8 machine at Harima. These will be high brilliance sources with a much harder radiation spectrum that will offer many new possibilities for powder diffraction experiments, especially at energies above 10 keV.

Cox, D. E.

1999-04-23

124

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

125

Measurements of Powder-Polymer Mixture Properties and Their Use in Powder Injection Molding Simulations for Aluminum Nitride  

NASA Astrophysics Data System (ADS)

Aluminum nitride has been favored for applications in manufacturing substrates for heat sinks due to its elevated temperature operability, high thermal conductivity, and low thermal expansion coefficient. Powder injection molding is a high-volume manufacturing technique that can translate these useful material properties into complex shapes. In order to design and fabricate components from aluminum nitride, it is important to know the injection-molding behavior at different powder-binder compositions. However, the lack of a materials database for design and simulation at different powder-polymer compositions is a significant barrier. In this paper, a database of rheological and thermal properties for aluminum nitride-polymer mixtures at various volume fractions of powder was compiled from experimental measurements. This database was used to carry out mold-filling simulations to understand the effects of powder content on the process parameters and defect evolution during the injection-molding process. The experimental techniques and simulation tools can be used to design new materials, select component geometry attributes, and optimize process parameters while eliminating expensive and time-consuming trial-and-error practices prevalent in the area of powder injection molding.

Kate, Kunal H.; Onbattuvelli, Valmikanathan P.; Enneti, Ravi K.; Lee, Shi W.; Park, Seong-Jin; Atre, Sundar V.

2012-09-01

126

Preparation of superconductor precursor powders  

DOEpatents

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

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

1995-01-01

127

powder in water  

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

128

Powder processing of hybrid titanium neural electrodes  

NASA Astrophysics Data System (ADS)

A preliminary investigation into the powder production of a novel hybrid titanium neural electrode for EEG is presented. The rheological behavior of titanium powder suspensions using sodium alginate as a dispersant are examined for optimal slip casting conditions. Electrodes were slip cast and sintered at 950癈 for 1 hr, 1000癈 for 1, 3, and 6 hrs, and 1050癈 for 1 hr. Residual porosities from sintering are characterized using Archimedes' technique and image analysis. The pore network is gel impregnated by submerging the electrodes in electrically conductive gel and placing them in a chamber under vacuum. Gel evaporation of the impregnated electrodes is examined. Electrodes are characterized in the dry and gelled states using impedance spectrometry and compared to a standard silver- silver chloride electrode. Power spectral densities for the sensors in the dry and gelled state are also compared. Residual porosities for the sintered specimens were between 50.59% and 44.81%. Gel evaporation tests show most of the impregnated gel evaporating within 20 min of exposure to atmospheric conditions with prolonged evaporation times for electrodes with higher impregnated gel mass. Impedance measurements of the produced electrodes indicate the low impedance of the hybrid electrodes are due to the increased contact area of the porous electrode. Power spectral densities of the titanium electrode behave similar to a standard silver-silver chloride electrode. Tests suggest the powder processed hybrid titanium electrode's performance is better than current dry contact electrodes and comparable to standard gelled silver-silver chloride electrodes.

Lopez, Jose Luis, Jr.

129

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

130

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

131

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

132

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

133

Shock compaction of molybdenum powder  

NASA Technical Reports Server (NTRS)

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

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

1983-01-01

134

Method for molding ceramic powders  

DOEpatents

A method for molding ceramic powders comprises forming a slurry mixture including ceramic powder, a dispersant for the metal-containing powder, and a monomer solution. The monomer solution includes at least one multifunctional monomer, a free-radical initiator, and an organic solvent. The slurry mixture is transferred to a mold, and the mold containing the slurry mixture is heated to polymerize and crosslink the monomer and form a firm polymer-solvent gel matrix. The solid product may be removed from the mold and heated to first remove the solvent and subsequently remove the polymer, where after the product may be sintered.

Janney, M.A.

1990-01-16

135

Method for molding ceramic powders  

DOEpatents

A method for molding ceramic powders comprises forming a slurry mixture including ceramic powder, a dispersant for the metal-containing powder, and a monomer solution. The monomer solution includes at least one multifunctional monomer, a free-radical initiator, and an organic solvent. The slurry mixture is transferred to a mold, and the mold containing the slurry mixture is heated to polymerize and crosslink the monomer and form a firm polymer-solvent gel matrix. The solid product may be removed from the mold and heated to first remove the solvent and subsequently remove the polymer, whereafter the product may be sintered.

Janney, Mark A. (Knoxville, TN)

1990-01-01

136

Laser production of articles from powders  

DOEpatents

Method and apparatus for forming articles from materials in particulate form in which the materials are melted by a laser beam and deposited at points along a tool path to form an article of the desired shape and dimensions. Preferably the tool path and other parameters of the deposition process are established using computer-aided design and manufacturing techniques. A controller comprised of a digital computer directs movement of a deposition zone along the tool path and provides control signals to adjust apparatus functions, such as the speed at which a deposition head which delivers the laser beam and powder to the deposition zone moves along the tool path.

Lewis, Gary K. (Los Alamos, NM); Milewski, John O. (Santa Fe, NM); Cremers, David A. (Los Alamos, NM); Nemec, Ronald B. (White Rock, NM); Barbe, Michael R. (White Rock, NM)

1998-01-01

137

Laser production of articles from powders  

DOEpatents

Method and apparatus for forming articles from materials in particulate form in which the materials are melted by a laser beam and deposited at points along a tool path to form an article of the desired shape and dimensions. Preferably the tool path and other parameters of the deposition process are established using computer-aided design and manufacturing techniques. A controller comprised of a digital computer directs movement of a deposition zone along the tool path and provides control signals to adjust apparatus functions, such as the speed at which a deposition head which delivers the laser beam and powder to the deposition zone moves along the tool path. 20 figs.

Lewis, G.K.; Milewski, J.O.; Cremers, D.A.; Nemec, R.B.; Barbe, M.R.

1998-11-17

138

Rotary powder feed through apparatus  

DOEpatents

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

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

2001-01-01

139

Neutron detectors comprising boron powder  

SciTech Connect

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

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

2013-05-21

140

Luminescence of powdered uranium glasses  

NASA Technical Reports Server (NTRS)

Measurement of cathodoluminescence and photoluminescence efficiencies in powdered borosilicate glasses having different particle size and different uranium content. Excitation with 100 to 350 keV electrons and with 253.7 nm light was found to produce identical absolute radiant exitance spectra in powdered samples. The most efficient glass was one containing 29.4 wt% B2O3, 58.8 wt% SiO2, 9.8 wt% Na2O and 2.0 wt% UO2.

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

1974-01-01

141

Powder collection apparatus/method  

DOEpatents

Device for separating and collecting ultrafine atomized powder from the gas stream of a gas atomizing apparatus comprises a housing having an interior wall oriented at an angle relative to horizontal so as to form a downwardly converging, conical expansion chamber, an inlet conduit communicated to the expansion chamber proximate an upper region thereof for receiving the gas stream, and an outlet proximate a lower region of the expansion chamber. The inlet conduit is oriented at a compound inclined angle (with respect to horizontal) selected to promote separation and collection of powder from the gas stream in the expansion chamber. The compound angle comprises a first entrance angle that is greater than the angle of repose of the powder on the housing interior wall such that any powder accumulation in the inlet conduit tends to flow down the wall toward the outlet. The second angle is selected generally equal to the angle of the housing interior wall measured from the same horizontal plane so as to direct the gas stream into the expansion chamber generally tangent to the housing interior wall to establish a downward swirling gas stream flow in the expansion chamber. A powder collection container is communicated to the outlet of the expansion chamber to collect the powder for further processing. 4 figures.

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

1994-01-11

142

Powder collection apparatus/method  

DOEpatents

Device for separating and collecting ultrafine atomized powder from the gas stream of a gas atomizing apparatus comprises a housing having an interior wall oriented at an angle relative to horizontal so as to form a downwardly converging, conical expansion chamber, an inlet conduit communicated to the expansion chamber proximate an upper region thereof for receiving the gas stream, and an outlet proximate a lower region of the expansion chamber. The inlet conduit is oriented at a compound inclined angle (with respect to horizontal) selected to promote separation and collection of powder from the gas stream in the expansion chamber. The compound angle comprises a first entrance angle that is greater than the angle of repose of the powder on the housing interior wall such that any powder accumulation in the inlet conduit tends to flow down the wall toward the outlet. The second angle is selected generally equal to the angle of the housing interior wall measured from the same horizontal plane so as to direct the gas stream into the expansion chamber generally tangent to the housing interior wall to establish a downward swirling gas stream flow in the expansion chamber. A powder collection container is communicated to the outlet of the expansion chamber to collect the powder for further processing.

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

1994-01-11

143

Powder diffraction from a continuous microjet of submicrometer protein crystals.  

PubMed

Atomic-resolution structures from small proteins have recently been determined from high-quality powder diffraction patterns using a combination of stereochemical restraints and Rietveld refinement [Von Dreele (2007), J. Appl. Cryst. 40, 133-143; Margiolaki et al. (2007), J. Am. Chem. Soc. 129, 11865-11871]. While powder diffraction data have been obtained from batch samples of small crystal-suspensions, which are exposed to X-rays for long periods of time and undergo significant radiation damage, the proof-of-concept that protein powder diffraction data from nanocrystals of a membrane protein can be obtained using a continuous microjet is shown. This flow-focusing aerojet has been developed to deliver a solution of hydrated protein nanocrystals to an X-ray beam for diffraction analysis. This method requires neither the crushing of larger polycrystalline samples nor any techniques to avoid radiation damage such as cryocooling. Apparatus to record protein powder diffraction in this manner has been commissioned, and in this paper the first powder diffraction patterns from a membrane protein, photosystem I, with crystallite sizes of less than 500 nm are presented. These preliminary patterns show the lowest-order reflections, which agree quantitatively with theoretical calculations of the powder profile. The results also serve to test our aerojet injector system, with future application to femtosecond diffraction in free-electron X-ray laser schemes, and for serial crystallography using a single-file beam of aligned hydrated molecules. PMID:18955765

Shapiro, D A; Chapman, H N; Deponte, D; Doak, R B; Fromme, P; Hembree, G; Hunter, M; Marchesini, S; Schmidt, K; Spence, J; Starodub, D; Weierstall, U

2008-11-01

144

Production of Dry Powder Clots Using Piezoelectric Drop Generator  

SciTech Connect

We have demonstrated that piezoelectrically driven, squeeze mode, tubular reservoir liquid drop generation, originally developed as a ''drop-on-demand'' method for ejection of microdrops of pure liquid or liquid suspensions of powdered bulk materials, can successfully operate with dry powder. Spherical silver powder with maximum particle diameter of 20 {micro}m (-635 mesh) was loaded into and ejected from a 100 {micro}m orifice glass dropper with flat piezoelectric disk driver. Time of flight experiments were performed to optimize the dropper operation parameters and to determine the size and velocity of the ejected particles. It was found that at certain values of the amplitude, duration, and repetition rate of the voltage pulses applied to the dropper piezoelectric disk, one can produce ejection of powder clots of a stable size, comparable with the dropper orifice diameter. In contrast to the dropper operation with a liquid, in the case of silver powder, a clot is not ejected at each high voltage pulse, but quasi-periodically with an interval corresponding to thousands of pulses. The application of the dry powder clot generation technique for injection of atoms into helium buffer gas at cryogenic temperatures is discussed.

Lee, Eric R

2002-09-05

145

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

SciTech Connect

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

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

1989-01-01

146

30 CFR 57.6901 - Black powder.  

Code of Federal Regulations, 2011 CFR

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

2011-07-01

147

30 CFR 56.6901 - Black powder.  

Code of Federal Regulations, 2012 CFR

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

2012-07-01

148

30 CFR 57.6901 - Black powder.  

Code of Federal Regulations, 2012 CFR

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

2012-07-01

149

30 CFR 57.6901 - Black powder.  

Code of Federal Regulations, 2013 CFR

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

2013-07-01

150

30 CFR 56.6901 - Black powder.  

Code of Federal Regulations, 2011 CFR

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

2011-07-01

151

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

152

30 CFR 56.6901 - Black powder.  

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

2014-07-01

153

30 CFR 57.6901 - Black powder.  

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

2014-07-01

154

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

155

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

156

Powder lubrication of faults by powder rolls in gouge zones  

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

157

Experimental methods for measuring the optimum amount of dispersant for seven Sumitomo alumina powders  

Microsoft Academic Search

Seven Sumitomo alumina powders of different surface areas and particle size distributions were studied with a view to determining the optimum amount of dispersant (Darvan 821A) required to stabilise aqueous suspensions prepared from the powders. Three different techniques were used; sedimentation, particle sizing and acoustophoresis. Acoustophoresis proved to be the most accurate and quickest way of establishing the optimum amount.

M. Burke; R. Greenwood; K. Kendall

1998-01-01

158

Adsorption of basic dyes from aqueous solution onto pumice powder  

Microsoft Academic Search

The adsorption of methylene blue and crystal violet on pumice powder samples of varying compositions was investigated using a batch adsorption technique. The effects of various experimental parameters, such as adsorbent dosage, initial dye concentration, and contact time, were also investigated. The extent of dye removal increased with decreased initial concentration of the dye and also increased with increased contact

Feryal Akbal

2005-01-01

159

Quality and authenticity of commercial aloe vera gel powders  

Microsoft Academic Search

This study provides a survey of commercial aloe vera gel powders. Nine products, obtained from leading international suppliers, were examined and compared with fresh aloe vera gel. A multi-technique approach was chosen to assess their quality and authenticity. Authenticity was evaluated by nuclear magnetic resonance spectrometry (1H NMR). The absence of adulterants, impurities, and preservatives was also investigated by this

A. Bozzi; C. Perrin; S. Austin; F. Arce Vera

2007-01-01

160

Chemical Preparation of Carbonated Calcium Hydroxyapatite Powders at 37  

E-print Network

NCONH2), at 37 C and pH of 7.4, by using a novel chemical precipitation technique. These powders were nearly equal to those of the inorganic constituents of human blood plasma, were 庐rst used by Kokubo et al and the most stable compound of calcium phosphate phases in aqueous solutions at pH values higher than 4

Tas, A. Cuneyt

161

Temperature analysis of the powder streams in coaxial laser cladding  

Microsoft Academic Search

The powder stream temperature of a newly developed coaxial laser cladding technique have been calculated and measured in this study. A simplified one-dimensional model of the particle heating problem under laser irradiation was solved with various conditions of laser intensity, particle size and flow velocity. The experimental results have been successfully detected by a pin-hole infrared sensor with the temperature

Jehnming Lin

1999-01-01

162

A simple model of powder catchment in coaxial laser cladding  

Microsoft Academic Search

High efficiency of the powder deposition in coaxial laser cladding is a key subject for this new technique adopted to the industry. A catchment model was proposed in this study to characterise the particle bonding under laser heating in the cladding process. The phenomena of the particle rebound and adhesion on substrate were discussed and the catchment efficiency was mathematically

Jehnming Lin

1999-01-01

163

1. Diffraction and the X-Ray Powder Diffractometer  

E-print Network

1. Diffraction and the X-Ray Powder Diffractometer 1.1 Diffraction 1.1.1 Introduction to Diffraction Materials are made of atoms. Knowledge of how atoms are arranged into crystal structures experimental techniques, but most of them involve diffraction. To date, most of our knowledge about the spatial

164

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

165

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

166

Studies of microstructural imperfections of powdered Zirconium-based alloys  

SciTech Connect

Different model based approaches of X-ray diffraction line profile analysis have been applied on the heavily deformed zirconium-based alloys in the powdered form to characterize the microstructural parameters like domain size, microstrain and dislocation density. In characterizing the microstructure of the material, these methods are complimentary to each other. Though the parameters obtained by different techniques are differently defined and thus not necessarily comparable, the values of domain size and microstrain obtained from the different techniques show similar trends.

Chowdhury, P.S. [Variable Energy Cyclotron Centre, 1/AF Bidhannagar, Kolkata-700 064 (India); Sarkar, A. [Mechanical Metallurgy Section, Bhabha Atomic Research Centre, Mumbai-400085 (India); Mukherjee, P., E-mail: paramita@vecc.gov.in [Variable Energy Cyclotron Centre, 1/AF Bidhannagar, Kolkata-700 064 (India); Gayathri, N.; Bhattacharya, M.; Barat, P. [Variable Energy Cyclotron Centre, 1/AF Bidhannagar, Kolkata-700 064 (India)

2010-11-15

167

Microwave-Induced Combustion Synthesis of Hexagonal Barium Ferrite Powders  

Microsoft Academic Search

A novel ceramic synthesis technique, microwave-assisted process was investigated for the production of Barium Hexagonal ferrite (BaFe^Oip) powders with improved physical properties. Compared to conventional synthetic route, the new method significantly shortened synthetic steps and reaction time. This technique involves the reaction of stoichiometric amount of metal nitrates and appropriate dosage of citric acid at microwave oven and the whole

Dong Limin; Han Zhidong; Wu Ze; Zhang Xianyou

2007-01-01

168

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

169

Ceramics in gas turbine: Powder and process characterization  

NASA Technical Reports Server (NTRS)

Some of the intrinsic properties of various forms of Si3N4 and SiC are listed and limitations of such materials' availability are pointed out. The essential features/parameters to characterize a batch of powder are discussed including the standard techniques for such characterization. In process characterization, parameters in sintering, reaction sintering, and hot pressing processes are discussed including the factors responsible for strength limitations in ceramic bodies. Significant improvements in material properties can be achieved by reducing or eliminating the strength limiting factors with consistent powder and process characterization along with process control.

Dutta, S.

1977-01-01

170

Compact, Non-Pneumatic Rock-Powder Samplers  

NASA Technical Reports Server (NTRS)

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

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

2008-01-01

171

Automated dry powder dispenser for explosive components  

SciTech Connect

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

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

1992-09-01

172

Automated dry powder dispenser for explosive components  

SciTech Connect

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

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

1992-01-01

173

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. Frettl鰄; Uwe Grimm

2007-01-01

174

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

175

DC Plasma Technology Applied to Powder Metallurgy: an Overview  

NASA Astrophysics Data System (ADS)

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

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

2013-01-01

176

Advanced composites take a powder  

SciTech Connect

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

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

1993-06-01

177

Polymer quenched prealloyed metal powder  

DOEpatents

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

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

2001-01-01

178

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

179

Processing and characterization of carob powder  

Microsoft Academic Search

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

Ali K. Yousif; H. M. Alghzawi

2000-01-01

180

Structural Color Painting by Rubbing Particle Powder  

PubMed Central

Structural colors originate from purely physical structures. Scientists have been inspired to mimic the structures found in nature, the realization of these structures still presents a great challenge. We have recently introduced unidirectional rubbing of a dry particle powder on a rubbery surface as a quick, highly reproducible means to fabricate a single crystal monolayer assembly of particles over an unlimited area. This study extends the particle-rubbing process to a novel fine-art painting, structural color painting (SCP). SCP is based on structural coloring with varying iridescence according to the crystal orientation, as controlled by the rubbing direction. This painting technique can be applied on curved surfaces, which enriches the objects to be painted and helps the painter mimic the structures found in nature. It also allows for quick fabrication of complicated particle-assembly patterns, which enables replication of paintings. PMID:25661669

Park, ChooJin; Koh, Kunsuk; Jeong, Unyong

2015-01-01

181

April 11, 2013 Powder Consolidation under Pressure  

E-print Network

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

Thomas, David D.

182

Advances in x-ray powder pattern data collection and its impact on unit cell indexing  

NASA Astrophysics Data System (ADS)

: Advances in x-ray powder pattern data collection and its impact on unit cell indexing. Simon Bates:: Bede Scientific Inc. Indexing of powder patterns is one of the major bottle necks for achievement of full structural solutions from powder data. The largest experimental uncertainty that limits the effectiveness of powder pattern indexing is a precise determination of the measured peak positions. Parallel beam x-ray diffraction optics allows the measurement of peak positions without the influence of any defocusing. When combined with a transmission geometry or +/- reflection geometry, the parallel beam optics allow the measurement of a powder sample using Bonds technique for absolute lattice parameter determination. In Bonds technique adapted from single crystal measurements, the powder pattern is collected from 0 to positive max_2Theta and then from 0 to negative max_2Theta. The folding of the two patterns removes any remaining peak positional errors. For the application of Bonds technique to be most effective, a goniometer with absolute linear positional encoding is required. Data will be presented on a wide range of powder samples covering metals and alloys, minerals and organic materials. It will be shown using Bond's method that for all material types the absolute peak positions can be determined over the complete measurement range with a positional uncertainty of the order of 0.005 degrees 2Theta. With measured peak positions of this positional accuracy, in most cases no special effort is required to index the full pattern.

Bates, Simon

2003-03-01

183

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

184

Powder Diffraction in Zeolite Science  

NASA Astrophysics Data System (ADS)

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

Burton, Allen W.

185

Pinwheel patterns and powder diffraction  

E-print Network

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

Michael Baake; Dirk Frettl鰄; Uwe Grimm

2006-10-06

186

Structure and magnetism of heat-treated nanocrystalline Cu80Co20 powders prepared via chemical means  

Microsoft Academic Search

Nanocrystalline Cu80Co20 powders were fabricated using a chemical precipitation technique. As-prepared powders consist of metal-oxides having an average particle size of 100 A?. When appropriately heat treated, these powders reduce to form a CuCo face-centered cubic alloy; heat treatments at higher temperatures (?400 癈) facilitate the phase separation of the alloy to its elemental components. Concurrent with an increase in

V. G. Harris; F. H. Kaatz; V. Browning; D. J. Gillespie; R. K. Everett; A. M. Ervin; W. T. Elam; A. S. Edelstein

1994-01-01

187

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

188

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

189

Anti-Corrosive Powder Particles  

NASA Technical Reports Server (NTRS)

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

Parker, Donald; MacDowell, Louis, III

2005-01-01

190

Compositionally continuously graded cathode layers of (Ba0.5Sr0.5)(Fe0.91Al0.09)O3-?-Gd0.1Ce0.9O2 by wet powder spraying technique for solid oxide fuel cells  

NASA Astrophysics Data System (ADS)

Compositionally continuously graded cathode layers (CGCLs) of (Ba0.5Sr0.5)(Fe0.91Al0.09)O3-?-Gd0.1Ce0.9O2 (BSFA-GDC) have been constructed by a handy and effective technique called wet powder spraying (WPS). CGCLs exhibit similar thermal expansion coefficient (TEC) value between adjacent thin layers. The continuously graded structure and the well-distributed components of BSFA-GDC cathode are confirmed by morphological characterization with scanning electron microscopy (SEM), and by compositional analysis with energy dispersion X-ray spectrometer (EDS), respectively. The polarization resistance (Rp) of CGCLs with three different thicknesses is investigated by electrochemical impedance spectra (EIS). The EIS results show that CGCLs with a moderate thickness of 20?m achieve the lowest Rp of 0.301?燾m2 at 800牥C. In addition, anode-supported single cells with the configuration of NiO-YSZ/YSZ/GDC/BSFA-GDC have been fabricated and tested. The cell with the CGCLs thickness of 20?m reaches the highest output power density of 848爉W燾m-2 at 800牥C.

Jiang, Taizhi; Wang, Zhenhua; Ren, Baiyu; Qiao, Jinshuo; Sun, Wang; Sun, Kening

2014-02-01

191

Treatment of refractory powders by a novel, high enthalpy dc plasma  

NASA Astrophysics Data System (ADS)

Thermophysical properties of CO2-CH4 mixtures at high temperatures are very attractive for materials processing. In comparison with argon, at the same temperature, such a mixture possesses much higher enthalpy and higher thermal conductivity. At high temperatures, CO2-CH4 mixture has a complex composition with strong presence of CO which, in the case of powder treatment, could reduce oxidation. In this work, a dc plasma torch with graphite cathode was used to study the effect of plasma gas composition on spheroidization of tungsten carbide and alumina powders. Two different gas compositions were used to generate the plasma while the torch current was kept at 300 A. Various techniques were employed to assess the average concentration of carbides and oxides and the final shape of the treated powders. Process parameters such as input power and plasma gas composition allow controlling the degree of powder oxidation and spheroidization of high melting point ceramic powders.

Pershin, L.; Mitrasinovic, A.; Mostaghimi, J.

2013-06-01

192

Preparation of ceramic grade UO 2 powder by atomization from uranyl nitrate solutions  

NASA Astrophysics Data System (ADS)

The thermal denitration of a nitrate solution by direct conversion to a ceramic grade uranium dioxide powder, in a furnace that combines atomization nozzle and gas stirred bed, is an attractive method because no liquid waste products are formed and it has relative simplicity. The UO 2 powder characteristics, such as size, shape, specific surface area and sinterability as a function of procedural variables were determined. This technique has been developed in the pelleting pilot plant of the IPEN/CNEN-SP and it appears to be practical and economically feasible for wet recovery of rejected UO 2 powders and pellets from production process, with the recovered powder being directly mixed to the powder from the AUC reduction process.

Lainetti, P.; Riella, H. Gracher

1991-02-01

193

Powder Diffraction from a Continuous Micro-Jet of sub-micron Protein Crystals  

E-print Network

Powder diffraction rings have been obtained from sub-micron protein crystallites in a water jet, and the data analysed. Previous powder diffraction has used a suspension of small crystallites, and long exposures, causing significant X-ray damage. We show here that protein powder data from nano-crystals can be obtained using a continuous micro-jet. This allows more efficient use of crystal growth solutions containing nanocrystals and the much shorter exposures needed for next-generation synchrotrons. This method requires neither the crushing of larger polycrystalline samples nor any techniques to avoid radiation damage such as cryo-cooling. We have commissioned an apparatus to record protein powder diffraction in this manner and in this paper present the first such patterns from photosystem I protein crystals with sizes less than 500 nm. These preliminary patterns show the lowest order reflections, which agree quantitatively with theoretical calculations of the powder profile. The results serve also to test ou...

Shapiro, D A; Doak, R B; Fromme, P; Hembree, G; Hunter, M; Marchesini, S; Schmidt, K; Starodub, D; Weierstall, U; Chapman, H; Spence, J

2008-01-01

194

The thermal spray processing of HA powders and coatings  

NASA Astrophysics Data System (ADS)

In recent years, coated implants have been actively researched and put to use in many biomedical engineering applications. The coating used on the implants is hydroxyapatite (HA), a calcium-phosphate compound with attractive bioactive and biocompatible properties that can enhance the fixation process of biomedical implants. Thermal spraying provides a potent means for depositing the HA coatings on implants. Among the populat thermal-spray techniques are combustion-flame spray, plasma spray, and high-velocity oxy-fuel spray. This article investigates the versatility of thermal-spray techniques to perform spheroidization of HA powders, the preparation of HA-based biocomposite powders and coatings, and the deposition of HA coatings.

Khor, K. A.; Cheang, P.; Wang, Y.

1997-02-01

195

Micro powder metallurgy for the replicative production of metallic microstructures  

Microsoft Academic Search

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

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

2002-01-01

196

Characterization of polymer materials and powders for selective laser melting  

NASA Astrophysics Data System (ADS)

Concerning individualization, the requirements to products have increased. The trend towards individualized serial products faces manufacturing techniques with demands of increasing flexibility. Additive manufacturing techniques generate components directly out of a CAD data set while requiring no specific tool or form. Due to this additive manufacturing processes comply, in opposite to conventional techniques, with these increased demands on processing technology. With a variety of available additive manufacturing techniques, some of them have a high potential to generate series products with reproducible properties. Selective laser melting (SLM) of powder materials shows the highest potential for this application. If components made by SLM are desired to be applied in technical series products, their achievable properties play a major part. These properties are mainly determined by the processed materials. The range of present commercially available materials for SLM of polymer powders is limited. This paper shows interrelations of various material properties to create a basic understanding of sintering processes and additional qualifying new materials. Main properties of polymer materials, with regard to their consolidation are viscosity and surface energy. On the one hand the difference of the surface energy between powder and melt influences, the wetting behavior, and thus the penetration depth. On the other hand, a high surface tension is fundamental for good coalescence of bordering particles. To fulfill these requirements limits of the surface tension will be determined on the basis of a reference material. For these reason methods for determining surface tension of solids, powders and melts are analyzed, to carry out a possible process-related material characterization. Not only an insight into observed SLM phenomena is provided but also hints concerning suitable material selection.

Wudy, K.; Drummer, D.; Drexler, M.

2014-05-01

197

Evaluation of Factors Affecting Powdered Drug Reconstitution in Microgravity  

NASA Technical Reports Server (NTRS)

Owing to the high cost of transporting mass into space, and the small volume available for equipment in the Space Shuttle Orbiter and the International Space Station, refrigeration space is extremely limited. For this reason, there exists strong motivation for transporting certain drugs in powdered form so that they do not require refrigeration. When needed, the powdered drug will be mixed with saline to obtain a liquid form that may be injected intravenously. While this is a relatively simple task in a 1-G environment, there are some difficulties that may be encountered in 0-G. In non-accelerated spaceflight, gravitational and inertial forces are eliminated allowing other smaller forces, such as capillary forces and surface tension, to dominate the behavior of fluids. For instance, water slowly ejected from a straw will tend to form a sphere, while fluid in a container will tend to wet the inside surface forming a highly rounded meniscus. Initial attempts at mixing powdered drugs with saline in microgravity have shown a tendency toward forming foamy emulsions instead of the desired homogeneous solution. The predominance of adhesive forces between the drug particles and the interface tensions at the gas/liquid and solid/liquid interfaces drastically reduce the rate of deaggregation of the drug powder and also reduce the rate of absorption of saline by the powder mass. In addition, the capillary forces cause the saline to wet the inside of the container, thus trapping air bubbles within the liquid. The rate of dissolution of a powder drug is directly proportional to the amount of surface area of the solid that is exposed to liquid solvent. The surface area of drug that is in contact with the liquid is greatly reduced in microgravity and, as a result, the dissolution rate is reduced as well. The KC-135 research described here was aimed at evaluating the extent to which it is possible to perform drug reconstitution in the weightlessness of parabolic flight using standard pharmacological supplies. The experiment included a parametric assessment of possible factors affecting the reconstitution process. The specific questions that we wished to answer were: (1) Is it possible to reconstitute powdered drugs in weightlessness using standard pharmacological equipment? (2) What are the differences between drug reconstitution in a 1-G and a 0-G environment? (3) What techniques of mixing the drug powder and diluent are more successful? (4) What physical and chemical factors play a role in determining the success of mixing and dissolution? (5) Is it necessary to employ crewmember and equipment restraints during the reconstitution process?

Schaffner, Grant; Johnston, Smith; Marshburn, Tom

1999-01-01

198

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.

199

An Investigation Into Mechanochemical Synthesis of Nanocrystalline Hexaferrite Powder  

NASA Astrophysics Data System (ADS)

Nanocrystalline strontium hexaferrite powder has been prepared by a new mechanochemical method in which the single phase hexaferrite was obtained via a sol-gel autocombustion process followed by an intermediate high energy milling step and subsequent annealing. The effects of the intermediate milling on the phase evolution, crystallite size and annealing behavior of the final products were investigated using the X-ray diffraction (XRD) technique. The single phase strontium hexaferrite was obtained at an annealing temperature of 800癈, while this temperature was 1,000癈 for the powder synthesized without milling. It could be seen that an intermediate milling accelerates the formation of strontium hexaferrite during the calcination process. The results showed that in the milled powder, the average crystallite size of the ferrite was about 40 nm and much smaller than that of the nonmilled powder. Magnetic properties were also measured by a vibrating sample magnetometer (VSM). The particle morphology was then studied by scanning and transmission electron microscopes (SEM and TEM).

Sadeghi-Niaraki, S.; Seyyed Ebrahimi, S. A.; Raygan, Sh.

200

New processing technique for DEB powder for thermal batteries  

Microsoft Academic Search

The purpose of this paper is to explore how material processing influences thermal battery performance, and how battery performance can be improved by changes in processing. This discussion is confined to the class of thermal batteries designed by Sandia Laboratories and built under the supervision of General Electric in St. Petersburg, Florida. The electrochemical system employed is: Ca\\/LiCl-KCl-CaCrO鈂\/Fe. These batteries

R. Szwarc; R. D. Walton

1980-01-01

201

Design and development of powder processed Fe朠 based alloys  

Microsoft Academic Search

The present investigation deals with designing Fe, Fe朠 binary and Fe朠朣i ternary alloys produced by an in-house developed powder metallurgical technique based on 慔ot Powder Preform Forging. Proper soaking of preforms at high temperature (1050癈) eliminates iron-phosphide eutectic and brings entire phosphorus into solution in iron. Attempting hot forging thereafter completely eliminates hot as well as cold shortness and thereby

Deepika Sharma; Kamlesh Chandra; Prabhu Shanker Misra

2011-01-01

202

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

NASA Astrophysics Data System (ADS)

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 900癈.

Khalifa, Marouan; Hajji, Messaoud; Ezzaouia, Hatem

2012-08-01

203

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

PubMed

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 900癈. PMID:22873706

Khalifa, Marouan; Hajji, Messaoud; Ezzaouia, Hatem

2012-01-01

204

Fabrication of transparent lead lanthanum zirconate titanate ceramics from fine powders by two-stage sintering  

Microsoft Academic Search

This paper reports that transparent lead lanthanum zirconate titanate (PLZT) ceramics were fabricated from fine powders using an inexpensive two-stage sintering technique. The powders were prepared by hydrolysis from low-cost inorganic precursors. In the two-stage sintering method, uniaxially pressed green pelets were densified to nearly theoretical values in an oxygen gas atmosphere during the first-stage sintering, at 1000[degrees]C for 1

Yoshio Yoshikawa; Kaoru Tsuzuki

1992-01-01

205

Grinding Si3N4 Powder In Si3N4 Equipment  

NASA Technical Reports Server (NTRS)

Three methods of grinding compared. Report based on study of grinding silicon nitride powder in preparation for sintering into solid ceramic material. Attrition, vibratory, and ball mills lined with reaction-bonded silicon nitride tested. Rates of reduction of particle sizes and changes in chemical compositions of powders measured so grinding efficiences and increases in impurity contents from wear of mills and media evaluated for each technique.

Herbell, Thomas P.; Freedman, Marc R.; Kiser, James D.

1989-01-01

206

Thixoforming of Stellite Powder Compacts  

NASA Astrophysics Data System (ADS)

Thixoforming involves processing metallic alloys in the semi-solid state. The process requires the microstructure to be spheroidal when part-solid and part-liquid i.e. to consist of solid spheroids surrounded by liquid. The aim of this work was to investigate whether powder compacts can be used as feedstock for thixoforming and whether the consolidating pressure in the thixoformer can be used to remove porosity from the compact. The powder compacts were made from stellite 6 and stellite 21 alloys, cobalt-based alloys widely used for e.g. manufacturing prostheses. Isothermal heat treatments of small samples in the consolidated state showed the optimum thixoforming temperature to be in the range 1340癈-1350癈 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

207

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

208

Modeling of laser cladding with powder injection  

Microsoft Academic Search

Laser cladding is one of the material additive manufacturing processes used to produce a metallurgically bonded deposition\\u000a layer. To obtain a high-quality resulting part, a deep understanding of the underlying mechanisms is required. In this article,\\u000a a mathematical model is developed to simulate the coaxial laser-cladding process with powder injection, which includes laser-\\u000a substrate, laser-powder, and powder-substrate interactions. The model

L. Han; K. M. Phatak; F. W. Liou

2004-01-01

209

Synthesis of mullite powders by acrylamide polymerization.  

SciTech Connect

Mullite (3Al{sub 2}O{sub 3} {center_dot} 2SiO{sub 2}) ceramics and composites are widely used. Synthesis of mullite powders, especially those that can be readily sintered, remains a focus of much current research. In support of recent efforts to fabricate mullite fibrous monoliths and to use superplastic flow to join ceramics, we have looked to synthesize reactive mullite powders. Recent advances in application of acrylamide polymers to ceramic synthesis offer promise of obtaining large quantities of high-quality powder at relatively low cost. We report here on synthesis from acrylamide monomers of mullite powders of two interesting particle sizes.

Sin, A.; Picciolo, J. J.; Lee, R. H.; Gutierrez-Mora, F.; Goretta, K. C.; Energy Technology; INPG-CNRS

2001-09-01

210

Dendritic microstructure in argon atomized superalloy powders  

NASA Technical Reports Server (NTRS)

The dendritic microstructure of atomized nickel base superalloy powders (Ni-20 pct Cr, NIMONIC-80A, ASTROALOY, and ZHS6-K) was studied. Prealloyed vacuum induction melted ingots were argon-atomized, the powders were cooled to room temperature, and various powder-size fractions were examined by optical metallography. Linear correlations were obtained for the powder size dependence of the secondary dendrite arm spacing, following the expected d-alpha (R) to the m power dependence on the particle size for all four superalloy compositions. However, the Ni-20 pct Cr alloy, which had much coarser arm spacing as compared to the other three alloys, had a much larger value of m.

Tewari, S. N.; Kumar, Mahundra

1986-01-01

211

Laser densification of alumina powder beds generated using aerosol assisted spray deposition  

Microsoft Academic Search

Layered manufacturing involves a range of techniques in which objects can be constructed in a laminated form. Therefore, the deposition technique is a critical part of direct-layered fabrication technologies. In this paper, aerosol assisted spray deposition has been applied to generate spraying of a suspension to prepare powder beds for subsequent selective laser sintering. First, an investigation on preparation of

Yiquan Wu; Jing Du; Kwang-Leong Choy; Larry L. Hench

2007-01-01

212

Effects of the impact angle variations on the erosion rate of glass in powder blasting process  

Microsoft Academic Search

Sandblasting, a conventional technique which is used for paint or scale removing, deburring, and glass decorating, has recently been developed into a powder blasting technique for brittle materials capable of producing micro-structures larger than 100牭m. This article describes an investigation of the effects of the impact angle of particles, the scanning times, and the standoff distance on the surface roughness,

Myeong-Woo Cho; Honghee Lee

2004-01-01

213

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

E-print Network

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

Colton, Jonathan S.

214

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.

215

Integration algorithms of elastoplasticity for ceramic powder compaction  

E-print Network

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

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

2014-04-24

216

Automated thermal conductivity probe, and applications to powders  

SciTech Connect

A thermal conductivity probe has been developed for measurements of powders and porous media from ambient temperature to 1300 K in vacuum or an inert gas atmosphere. Automated data acquisition and graphical analysis programs have been developed in FORTRAN for use with a laboratory mini-computer. Nonlinear data analysis techniques are available which can account for the thermal probe response due to contact resistance and probe thermal mass effects. Programs have also been developed with thermal BASIC for use with a small, portable desktop computer system. Examples of the use of the probe and data acquisition and analysis system are shown for measurement of the effective thermal conductivity of ceramic and metal powders.

Drotning, W D

1983-01-01

217

Sintering study of nanocrystalline tungsten carbide powders  

Microsoft Academic Search

WC powder with an average grain size of 6 nm was obtained after high energy ball milling under protective gas atmosphere. The kinetics of densification was studied during sintering the powder in a dilatometer up to 1450 癈. The microstructure was investigated by TEM and high resolution SEM after various stages of sintering. The green density of the specimens was

G. R. Goren-Muginstein; S. Berger; A. Rosen

1998-01-01

218

Optical properties of cathodochromic powder screens  

NASA Astrophysics Data System (ADS)

Melamed's diffuse reflectance for powdered materials is discussed in conjunction with its application for cathodochromic powder screens. Adaptation of the model was introduced through the modification of geometrical factor xu which is now to be empirically established for given screen. Experimental evidence obtained for cathodochromic bromosodalite well supports proposed modification.

Maszara, W. P.; Todd, L. T., Jr.

1985-07-01

219

Insolubility of milk powder products A minireview  

E-print Network

Review Insolubility of milk powder products 颅 A minireview Alan J. BALDWIN* Fonterra Research Abstract 颅 In this paper, the formation of insolubility in milk powder is described, and the factors diff茅rences d'ordres de grandeur des taux d'humidit茅. L'effet des r茅actifs chimiques sur l'茅tendue de la

Boyer, Edmond

220

Applied fractal geometry and powder technology  

Microsoft Academic Search

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

B. H. Kaye

1995-01-01

221

Slip casting and nitridation of silicon powder  

NASA Technical Reports Server (NTRS)

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.

1985-01-01

222

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

223

Wet powder seal for gas containment  

SciTech Connect

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

Stang, L.G.

1982-01-19

224

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

225

Flow of Damp Powder in a Rotating Impervious Cone Flow of Damp Powder in a Rotating Impervious Cone  

E-print Network

the interfacial friction law for the flow of a damp powder past an impervious wall. 2 Introduction 2.1 The conicalFlow of Damp Powder in a Rotating Impervious Cone Flow of Damp Powder in a Rotating Impervious Cone, axisymmetric flow of damp powder within a rotating impervious cone. The powder spins with the cone

Fleck, Norman A.

226

Combustion synthesis process for the rapid preparation of high-purity SrO powders  

NASA Astrophysics Data System (ADS)

A rapid, safe and simple technique for the production of high purity strontium oxide powders via a chemical combustion process is reported. The combustion reactions were performed to optimize the fuel to oxidizer ratios in the reaction mixtures required to obtain pure SrO powders by varying the molar ratio of chemical precursors and the temperature. The synthesized powders were characterized by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectrometry, infrared spectroscopy, differential scanning calorimetry, thermogravimetric analysis, and N2-physisorption measurements. The results indicate that crystalline SrO was obtained using a 1:1 strontium nitrate: urea molar ratio at 1000 癈 after 5 minutes. In addition, high-purity, homogeneous and crystalline SrO powders were easily produced in a short time via a chemical combustion process.

Granados-Correa, Francisco; Bonifacio-Mart韓ez, Juan

2014-12-01

227

21 CFR 520.1696b - Penicillin G powder.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 2013-04-01 false Penicillin G powder. 520.1696b Section...NEW ANIMAL DRUGS 520.1696b Penicillin G powder. (a) Specifications. Each gram of powder contains penicillin G potassium equivalent to...

2013-04-01

228

21 CFR 520.1696b - Penicillin G powder.  

...2014-04-01 2014-04-01 false Penicillin G powder. 520.1696b Section...NEW ANIMAL DRUGS 520.1696b Penicillin G powder. (a) Specifications. Each gram of powder contains penicillin G potassium equivalent to...

2014-04-01

229

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

2013-05-01

230

Preparation and characterization of uranyl oxalate powders  

NASA Astrophysics Data System (ADS)

Uranyl oxalate powders are prepared by adding 0.5 M oxalic acid solution to the uranyl nitrate (UNH) solutions purified with TBP extraction from dissolution of the Canada originated U 3O 8 commercial concentrate. Uranyl oxalate powders are identified by chemical analysis, TGA/DTG analysis, IR analysis and by single-crystal X-ray diffraction. The effects of the precipitation conditions on the powder properties are determined. A broad particle size distribution is obtained for all precipitation variants. These powders including very fine particles are difficult to filter and are not free flowing. The reactor and mixing type have a considerable effect on the powder properties of the uranyl oxalate powders. It was possible to ameliorate the filtration and the flowability to a certain degree using a conical air agitated reactor. The flowability of these powders is 0.4 g/s with a specific surface area 6.64 m 2/g and an average particle size of 11 ?m.

Tel, H.; B黮b黮, M.; Eral, M.; Alta?, Y.

1999-10-01

231

Dry powder formulation of simvastatin.  

PubMed

Objectives: This study focuses on the development of a dry powder inhaler (DPI) formulation of simvastatin (SV), and the effects of SV on the respiratory epithelium. Methods: Micronised SV samples were prepared by dry jet-milling. The long-term chemical stability and physicochemical properties of the formulations were characterised in terms of particles size, morphology, thermal and moisture responses. Furthermore, in vitro aerosol depositions were performed. The formulation was evaluated for cell viability and its effect on cilia beat activity, using ciliated nasal epithelial cells in vitro. The formulation transport across an established air interface Calu-3 bronchial epithelial cells and its ability to reduce mucus secretion was also investigated. Results: The particle size of the SV formulation and its aerosol performance were appropriate for inhalation therapy. Moreover, the formulation was found to be non-toxic to pulmonary epithelia cells and cilia beat activity up to a concentration of 10(-6) M. Transport studies revealed that SV has the ability to penetrate into airway epithelial cells and is converted into its active SV hydroxy acid metabolite. Single dose of SV DPI also decreased mucus production after 4 days of dosing. Conclusion: This therapy could potentially be used for the local treatment of diseases like chronic obstructive pulmonary disease, cystic fibrosis, and bronchiectasis given its anti-inflammatory effects and ability to reduce mucus production. PMID:25244365

Tulbah, Alaa S; Ong, Hui Xin; Morgan, Lucy; Colombo, Paolo; Young, Paul M; Traini, Daniela

2014-09-22

232

Dustiness of Fine and Nanoscale Powders  

PubMed Central

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 (0.337.9% and 0.131.8% 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 300nm to several micrometers, but no modes below 100nm, were observed. It is therefore unlikely that these materials would exhibit a substantial sub-100nm particle contribution in a workplace. PMID:23065675

Evans, Douglas E.; Baron, Paul A.

2013-01-01

233

Processing of laser formed SiC powder  

NASA Technical Reports Server (NTRS)

Processing research was undertaken to demonstrate that superior SiC characteristics could be achieved through the use of ideal constituent powders and careful post-synthesis processing steps. Initial research developed the means to produce approximately 1000 A uniform diameter, nonagglomerated, spherical, high purity SiC powders. Accomplishing this goal required major revision of the particle formation and growth model from one based on classical nucleation and growth to one based on collision and coalescence of Si particles followed by their carburization. Dispersions based on pure organic solvents as well as steric stabilization were investigated. Test parts were made by the colloidal pressing technique; both liquid filtration and consolidation (rearrangement) stages were modeled. Green densities corresponding to a random close packed structure were achieved. After drying, parts were densified at temperatures ranging from 1800 to 2100 C. This research program accomplished all of its major objectives. Superior microstructures and properties were attained by using powders having ideal characteristics and special post-synthesis processing procedures.

Haggerty, J. S.; Bowen, H. K.

1987-01-01

234

Pulsed high energy synthesis of fine metal powders  

NASA Technical Reports Server (NTRS)

Repetitively pulsed plasma jets generated by a capillary arc discharge at high stagnation pressure (>15,000 psi) and high temperature (>10,000 K) are utilized to produce 0.1-10 .mu.m sized metal powders and decrease cost of production. The plasma jets impact and atomize melt materials to form the fine powders. The melt can originate from a conventional melt stream or from a pulsed arc between two electrodes. Gas streams used in conventional gas atomization are replaced with much higher momentum flux plasma jets. Delivering strong incident shocks aids in primary disintegration of the molten material. A series of short duration, high pressure plasma pulses fragment the molten material. The pulses introduce sharp velocity gradients in the molten material which disintegrates into fine particles. The plasma pulses have peak pressures of approximately one kilobar. The high pressures improve the efficiency of disintegration. High gas flow velocities and pressures are achieved without reduction in gas density. Repetitively pulsed plasma jets will produce powders with lower mean size and narrower size distribution than conventional atomization techniques.

Witherspoon, F. Douglas (Inventor); Massey, Dennis W. (Inventor)

1999-01-01

235

Double-walled carbon nanotubes in composite powders.  

PubMed

Double-walled carbon nanotubes (DWNTs) may be interesting in many applications since the outer wall would provide an interface with the rest of the system, without modifying the inner wall. CNT-Fe/Fe3C-Al2O3 composite powders containing carbon nanotubes (CNTs) (65% of which are DWNTs) are prepared by reduction of an oxide solid solution in a H2-CH4 gas mixture. The powders and CNTs are studied by both local and macroscopical techniques. The influence of the reducing atmosphere composition and of the dwell time at 1050 degrees C is studied. There is a 6-fold increase in CNT content upon the increase in the CH4 content from 3 to 30 mol.%, but the formation of undesirable carbon nanofibers can also be promoted. A CH4 content of 12-18 mol.% is adapted for the particular iron content in these powders. Increasing the dwell time at 1050 degrees C results in the formation of CNTs with more walls. PMID:12908244

Flahaut, E; Peigney, A; Laurent, Ch

2003-01-01

236

Pulmonary drug delivery by powder aerosols.  

PubMed

The efficacy of pharmaceutical aerosols relates to its deposition in the clinically relevant regions of the lungs, which can be assessed by in vivo lung deposition studies. Dry powder formulations are popular as devices are portable and aerosolisation does not require a propellant. Over the years, key advancements in dry powder formulation, device design and our understanding on the mechanics of inhaled pharmaceutical aerosol have opened up new opportunities in treatment of diseases through pulmonary drug delivery. This review covers these advancements and future directions for inhaled dry powder aerosols. PMID:24818765

Yang, Michael Yifei; Chan, John Gar Yan; Chan, Hak-Kim

2014-11-10

237

Formulation considerations for dry powder inhalers.  

PubMed

The market for inhalable dry powder medication has consistently grown over past years. Targeting the lungs has been recognized to offer several advantages compared with oral application of drugs. The successive development of inhalation products has led to advances in local treatment of different respiratory diseases, but has also demonstrated the possibility to utilize the lungs for systemic drug delivery. Since a dry powder inhalation product is always a combination of drug formulation and inhalation device, the requirements for the development of such a system may be particularly complex. Therefore, this review aims to give an overview of the necessary considerations for a successful dry powder inhaler development. PMID:25090281

Cordts, Eike; Steckel, Hartwig

2014-06-01

238

Synthesis, Growth, Spectral and Optical Properties of Glycinyl Urea Single Crystal  

SciTech Connect

Single crystals of Glycinyl Urea were grown from aqueous solution by slow evaporation technique at room temperature. The cell parameters of the grown crystals were estimated by Single X-ray diffraction studies. The functional groups present in the grown crystals were ascertained using FTIR spectrum analysis. UV-visible transmittance spectrum was recorded to study the optical transparency of the grown crystal. The non-linear optical property has been tested by Kurtz powder technique.

Shanthi, N. Theresita [Department of Physics, V. V. College of engineering, Thisaiyanvilai-627 657, Tamilnadu (India); Selvarajan, P. [Department of Physics, Aditanar College of Arts and Science, Tiruchendur-628 216, Tamilnadu (India); Rose, A. S. J. Lucia [Department of Physics, St. Mary's College, Thoothukudi-628 001, Tamilnadu (India)

2011-10-20

239

Nano spray-dried pyrazinamide-l-leucine dry powders, physical properties and feasibility used as dry powder aerosols.  

PubMed

Abstract Objective: The aim of this study was to investigate the effect of adding l-leucine and using an ethanolic solvent on the physicochemical properties and aerodynamic behavior of nano spray-dried pyrazinamide (PZA)-l-leucine powders. Materials and methods: A nano spray dryer was employed to prepare PZA-l-leucine powders. The physicochemical properties were evaluated using a scanning electron microscope (SEM), differential scanning calorimetry and X-ray diffraction. The Andersen cascade impactor was used to evaluate the in vitro aerosolization performance of the sprayed powders. Results and discussion: The incorporation of l-leucine at 10% improved the percentage fine particle fraction (%FPF) in all ethanolic solvent formulations by up to nearly twofold (20.0-23.4%) compared to the normal spray-dried PZA of (8.8-13.0%). Changes in the particle density and morphology were also observed. The dense solid particles of PZA were completely converted to bulk hollow particles with a thin shell by increasing the l-leucine content up to 50%. Higher ethanol concentration resulted in larger dimensions of the hollow particle but did not directly affect the aerosolization performance. The co-spray dried PZA with 20% l-leucine in a 10% ethanol feed solvent gave the best aerosolization performance (FPF?=?33.0%). Conclusions: The co-spray dried PZA with a suitable l-leucine content using a nano spray drying technique could be applied to formulate the PZA DPI. PMID:25331092

Kaewjan, Kanogwan; Srichana, Teerapol

2014-10-21

240

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

241

21 CFR 73.2646 - Bronze powder.  

Code of Federal Regulations, 2011 CFR

...GENERAL LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION...specifications. The color additive bronze powder shall conform...amounts consistent with good manufacturing practice. (c) Labeling. The color additive and any mixture...

2011-04-01

242

21 CFR 73.2647 - Copper powder.  

Code of Federal Regulations, 2010 CFR

...GENERAL LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION...specifications. The color additive copper powder shall conform...amounts consistent with good manufacturing practice. (c) Labeling. The color additive and any mixture...

2010-04-01

243

21 CFR 73.2646 - Bronze powder.  

Code of Federal Regulations, 2010 CFR

...GENERAL LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION...specifications. The color additive bronze powder shall conform...amounts consistent with good manufacturing practice. (c) Labeling. The color additive and any mixture...

2010-04-01

244

21 CFR 73.2645 - Aluminum powder.  

Code of Federal Regulations, 2011 CFR

...GENERAL LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION...specifications. The color additive aluminum powder shall...amounts consistent with good manufacturing practice. (c) Labeling. The color additive and any mixture...

2011-04-01

245

21 CFR 73.2645 - Aluminum powder.  

Code of Federal Regulations, 2010 CFR

...GENERAL LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION...specifications. The color additive aluminum powder shall...amounts consistent with good manufacturing practice. (c) Labeling. The color additive and any mixture...

2010-04-01

246

21 CFR 73.2647 - Copper powder.  

Code of Federal Regulations, 2011 CFR

...GENERAL LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION...specifications. The color additive copper powder shall conform...amounts consistent with good manufacturing practice. (c) Labeling. The color additive and any mixture...

2011-04-01

247

Screening and classification of ceramic powders  

NASA Technical Reports Server (NTRS)

A summary is given of the classification technology of ceramic powders. Advantages and disadvantages of the wet and dry screening and classification methods are discussed. Improvements of wind force screening devices are described.

Miwa, S.

1983-01-01

248

Metal powder production by gas atomization  

NASA Technical Reports Server (NTRS)

The confined liquid, gas-atomization process was investigated. Results from a two-dimensional water model showed the importance of atomization pressure, as well as delivery tube and atomizer design. The atomization process at the tip of the delivery tube was photographed. Results from the atomization of a modified 7075 aluminum alloy yielded up to 60 wt pct. powders that were finer than 45 microns in diameter. Two different atomizer designs were evaluated. The amount of fine powders produced was correlated to a calculated gas-power term. An optimal gas-power value existed for maximized fine powder production. Atomization at gas-power greater than or less than this optimal value produced coarser powders.

Ting, E. Y.; Grant, N. J.

1986-01-01

249

21 CFR 169.179 - Vanilla powder.  

Code of Federal Regulations, 2011 CFR

...starch (including food starch-modified as prescribed in 172.892 of this chapter). (5) Dried corn sirup. (6) Gum acacia. Vanilla powder may contain one or any mixture of two or more of the anticaking ingredients specified in...

2011-04-01

250

21 CFR 169.179 - Vanilla powder.  

Code of Federal Regulations, 2013 CFR

...starch (including food starch-modified as prescribed in 172.892 of this chapter). (5) Dried corn sirup. (6) Gum acacia. Vanilla powder may contain one or any mixture of two or more of the anticaking ingredients specified in...

2013-04-01

251

21 CFR 169.179 - Vanilla powder.  

Code of Federal Regulations, 2010 CFR

...starch (including food starch-modified as prescribed in 172.892 of this chapter). (5) Dried corn sirup. (6) Gum acacia. Vanilla powder may contain one or any mixture of two or more of the anticaking ingredients specified in...

2010-04-01

252

21 CFR 169.179 - Vanilla powder.  

Code of Federal Regulations, 2012 CFR

...starch (including food starch-modified as prescribed in 172.892 of this chapter). (5) Dried corn sirup. (6) Gum acacia. Vanilla powder may contain one or any mixture of two or more of the anticaking ingredients specified in...

2012-04-01

253

21 CFR 169.179 - Vanilla powder.  

...starch (including food starch-modified as prescribed in 172.892 of this chapter). (5) Dried corn sirup. (6) Gum acacia. Vanilla powder may contain one or any mixture of two or more of the anticaking ingredients specified in...

2014-04-01

254

Magnesium Powder Metallurgy: Process and Materials Opportunities  

NASA Astrophysics Data System (ADS)

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

Bettles, Colleen J.

2008-06-01

255

Advances in beryllium powder consolidation simulation  

SciTech Connect

A fuzzy logic based multiobjective genetic algorithm (GA) is introduced and the algorithm is used to optimize micromechanical densification modeling parameters for warm isopressed beryllium powder, HIPed copper powder and CIPed/sintered and HIPed tantalum powder. In addition to optimizing the main model parameters using the experimental data points as objective functions, the GA provides a quantitative measure of the sensitivity of the model to each parameter, estimates the mean particle size of the powder, and determines the smoothing factors for the transition between stage 1 and stage 2 densification. While the GA does not provide a sensitivity analysis in the strictest sense, and is highly stochastic in nature, this method is reliable and reproducible in optimizing parameters given any size data set and determining the impact on the model of slight variations in each parameter.

Reardon, B.J.

1998-12-01

256

Continuous blending of dry pharmaceutical powders  

E-print Network

Conventional batch blending of pharmaceutical powders coupled with long quality analysis times increases the production cycle time leading to strained cash flows. Also, scale-up issues faced in process development causes ...

Pernenkil, Lakshman

2008-01-01

257

21 CFR 73.2646 - Bronze powder.  

Code of Federal Regulations, 2013 CFR

...GENERAL LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION...specifications. The color additive bronze powder shall conform...amounts consistent with good manufacturing practice. (c) Labeling. The color additive and any mixture...

2013-04-01

258

21 CFR 73.2645 - Aluminum powder.  

Code of Federal Regulations, 2012 CFR

...GENERAL LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION...specifications. The color additive aluminum powder shall...amounts consistent with good manufacturing practice. (c) Labeling. The color additive and any mixture...

2012-04-01

259

21 CFR 73.2646 - Bronze powder.  

Code of Federal Regulations, 2012 CFR

...GENERAL LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION...specifications. The color additive bronze powder shall conform...amounts consistent with good manufacturing practice. (c) Labeling. The color additive and any mixture...

2012-04-01

260

21 CFR 73.2646 - Bronze powder.  

...GENERAL LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION...specifications. The color additive bronze powder shall conform...amounts consistent with good manufacturing practice. (c) Labeling. The color additive and any mixture...

2014-04-01

261

21 CFR 73.2645 - Aluminum powder.  

Code of Federal Regulations, 2013 CFR

...GENERAL LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION...specifications. The color additive aluminum powder shall...amounts consistent with good manufacturing practice. (c) Labeling. The color additive and any mixture...

2013-04-01

262

21 CFR 73.2645 - Aluminum powder.  

...GENERAL LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION...specifications. The color additive aluminum powder shall...amounts consistent with good manufacturing practice. (c) Labeling. The color additive and any mixture...

2014-04-01

263

Biaxially textured articles formed by powder metallurgy  

DOEpatents

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

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

2001-01-01

264

Synthesis and processing of monosized oxide powders  

DOEpatents

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

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

1985-09-24

265

Adjustable Powder Injector For Vacuum Plasma Sprayer  

NASA Technical Reports Server (NTRS)

Attachment for plasma spray gun provides four degrees of freedom for adjustment of position and orientation at which powder injected externally into plasma flame. Manipulator provides for adjustment of pitch angle of injection tube: set to inject powder at any angle ranging from perpendicular to parallel to cylindrical axis. Scribed lines on extension bar and manipulator indicate pitch angle of extension tube. Collar changed to adapt injector to different gun.

Burns, D. H.; Woodford, W. H.; Mckechnie, T. N.; Mcferrin, D. C.; Davis, W. M.; Beason, G. P., Jr.

1993-01-01

266

Synthesis and processing of monosized oxide powders  

DOEpatents

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

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

1985-01-01

267

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

268

Characterization of poly(aminosiloxane) degradation at the alumina powder interface  

SciTech Connect

The interaction of N-2-aminoethyl-3-aminopropyltrimethoxysilane (AAPS) with alumina powder has been characterized by multiple techniques including thermal gravimetric analysis with mass spectrometry (TGA-MS), diffuse reflectance infrared spectroscopy (DRIFT), and ESCA. The TGA-MS and DRIFT techniques verify the existance of amine bicarbonates in neat AAPS polymer films, and on the alumina surface after treatment with AAPS as its natural pH. Upon heating, CO{sub 2} is evolved followed by the loss of an allyl amine fragment in the first stage of degradation, with the subsequent formation of an imine residue on the powder surface. TGA-MS shows that the weight fraction and rate of CO{sub 2} evolution at 90{degrees}C are higher in surface treated powders than in bulk films of poly(AAPS), whereas the rate of imine formation during AAPS decomposition is hindered on the alumina surface. Several mechanisms are hypothesized which are consistent with these trends.

Parker, A.A.; Kolek, P.L.; Ahern, A.M.; Balaba, W.; Armstrong, G.H. [Aluminum Co. of America, PA (United States)

1993-12-31

269

Ti Multicomponent Alloy Bulks by Powder Metallurgy  

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

270

Multiphase electrodispersion precipitation of zirconia powders  

SciTech Connect

The multiphase electrodispersion precipitation of zirconia powders has been done The multiphase in the electric dispersion reactor (EDR). This paper presents the first results obtained where the bench-scale EDR unit was operated in the continuous mode to synthesize 130 {+-} 2 g of ZrO{sub 2} powder in approximately 12 h. An aqueous solution of zirconyl nitrate was dispersed and precipitated in a 2-ethyl-l-hexanol continuous phase containing 0.012 {und M} to 0.12 {und M} ammonia. A gravity settler was used to remove soft agglomerates of the ZrO{sub 2} particles from the organic solvent. Electric bed filtration was employed to remove the fines from the solvent, which was then recycled. The particle-size distribution was varied by changing the electric field strength. At high field strengths (approximately 20 kV/cm), the particle sizes ranged from approximately 0.1 to 5 {mu}m. The dried powder had a consistency of talcum powder. Microwave and conventional heating experiments showed that the powders were sinterable. The BET surface area of the powders ranged from approximately 20 to 90 m{sup 2}/g.

Harris, M.T.; Sisson, W.G.; Scott, T.C.; Basaran, O.A.; Byers, C.H. [Oak Ridge National Lab., TN (United States). Chemical Technology Division; Ren, W.; Meek, T.T. [Univ. of Tennessee, Knoxville, TN (United States). Materials Science and Engineering Dept.

1994-12-31

271

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 癈 to 1100 癈]), 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?, 謟ge; Duman, Ismail; 講e鏾?lu, M. L黷fi

2011-06-01

272

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

2012-11-20

273

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

274

ACCURACY IN POWDER DIFFRACTION IV Critical parameters for  

E-print Network

ACCURACY IN POWDER DIFFRACTION IV Critical parameters for instrument alignment and performance validation of XRD instrumentation Gaithersburg, MD, USA April 22-25, 2013 1Accuracy in Powder Diffraction IV 路 Accuracy in Powder Diffraction starts with accurate powder diffraction data 颅 Also from laboratory

Magee, Joseph W.

275

Concentration mode of the powder stream in coaxial laser cladding  

Microsoft Academic Search

The blown powder laser cladding process has recently been greatly enhanced by the development of a coaxial powder feed system. It provides a new route to generate the metal parts directly from CAD drawings. The performance of the coaxial powder feeder depends on various gas flow streams which significantly affect the distribution mode of the powder stream and the deposition

Jehnming Lin

1999-01-01

276

Determination of flow properties of pharmaceutical powders by near infrared spectroscopy.  

PubMed

The physical properties of pharmaceutical powders are of upmost importance in the pharmaceutical industry. The knowledge of their flow properties is of critical significance in operations such as blending, tablet compression, capsule filling, transportation, and in scale-up operations. Powders flow properties are measured using a number of parameters such as, angle of repose, compressibility index (Carr's index) and Hausner ratio. To estimate these properties, specific and expensive equipment with time-consuming analysis is required. Near infrared spectroscopy is a fast and low-cost analytical technique thoroughly used in the pharmaceutical industry in the quantification and qualification of products. To establish the potential of this technique to determine the parameters associated with the flow properties of pharmaceutical powders, blended powders based on paracetamol as the active pharmaceutical ingredient were constructed in pilot scale. Spectra were recorded on a Fourier-transform near infrared spectrometer in reflectance mode. The parameters studied were the angle of repose, aerated and tapped bulk density. The correlation between the reference method values and the near infrared spectrum was performed by partial least squares and optimized in terms of latent variables using cross-validation. The near infrared based properties predictions were compared with the reference methods results. Prediction errors, which varied between 2.35% for the angle of repose, 2.51% for the tapped density and 3.18% for the aerated density, show the potential of NIR spectroscopy in the determination of physical properties affecting the flowability of pharmaceutical powders. PMID:20167448

Sarragu鏰, Mafalda C; Cruz, Ana V; Soares, Sandra O; Amaral, Helena R; Costa, Paulo C; Lopes, Jo鉶 A

2010-08-01

277

Synthesis and characterization of nano crystalline BaFe{sub 12}O{sub 19} powders by low temperature combustion  

SciTech Connect

Nano crystalline BaFe{sub 12}O{sub 19} powders have been prepared at a relatively low calcination temperature by a gel combustion technique using citric acid as a fuel/reductant and nitrates as oxidants. The effects of processing parameters, such as Ba/Fe ratio, citric acid/nitrates ratio, reaction temperature on the powder characteristics and magnetic properties of the resultant barium ferrites were investigated. By controlling the molar ratio of citric acid to metal nitrates, nano crystalline BaFe{sub 12}O{sub 19} powders with different particle sizes have been obtained. Phase attributes, microstructures and magnetic properties of the powders were characterized using X-ray diffraction analysis, X-ray line-broadening technique, Fourier transform infrared spectroscopy measurements, transmission electron microscopy and vibrating sample magnetometer. The maximum saturation magnetization value and intrinsic coercivity value for the obtained barium hexaferrites are 59.36 emu/g and 5540 Oe.

Huang Jianguo; Zhuang Hanrui; Li Wenlan

2003-01-01

278

Consolidation phenomena in laser and powder-bed based layered manufacturing  

Microsoft Academic Search

Layered manufacturing (LM) is gaining ground for manufacturing prototypes (RP), tools (RT) and functional end products (RM). Laser and powder bed based manufacturing (i.e. selective laser sintering\\/melting or its variants) holds a special place within the variety of LM processes: no other LM techniques allow processing polymers, metals, ceramics as well as many types of composites. To do so, however,

J.-P. Kruth; G. Levy; F. Klocke; T. H. C. Childs

2007-01-01

279

Magnetic properties and loss separation in iron powder soft magnetic composite materials  

Microsoft Academic Search

New developments in powder metallurgical composites make soft magnetic composite (SMC) material interesting for application in electrical machines, when combined with new machine design rules and new production techniques. In order to establish these design rules, one must pay attention to electromagnetic loss characteristics of SMC material. In this work, five different series of iron based SMCs are produced and

Marc de Wulf; Ljubomir Anestiev; Luc Dupr; Ludo Froyen; Jan Melkebeek

2002-01-01

280

Adsorptive Removal of Congo Red Dye Using Ultrasonically Pretreated Strychnos potatorum Seed Powder  

Microsoft Academic Search

This study highlights the removal of Congo red from its aqueous solution using Strychnos potatorum seed powder (SPSP), an Indian seed, used from ancient times for the treatment of turbid water. Surface activation of the adsorbent was carried out using ultra sonication techniques. Comparative studies on the uptake of the dye by both unsonicated and sonicated adsorbents were carried out.

Athinthra Krishnaswamy Sethurajan; Ashwin Ravichandran; Saravana Rajakumar Thangamani; Karuppan Muthukumar

2011-01-01

281

The contribution of frictional contacts to the shear strength of coarse glass bead powders and slurries  

Microsoft Academic Search

This paper investigates the use of the shear vane technique as a means of determining frictional and cohesive interparticle force contributions to the shear strength of coarse glass bead powders and slurries. To this end, the shear strength of 203-?m glass beads in air and slurried in water and kaolinite suspensions was determined as a function of vane immersion depth,

Adam P. Poloski; Paul R. Bredt; Richard C. Daniel; Avelino Eduardo Saez

2006-01-01

282

Development of a pungency measuring system for red-pepper powder  

Technology Transfer Automated Retrieval System (TEKTRAN)

Capsaicinoids are the main components that determine the spiciness level of red-pepper powders. Current pungency measurement is mostly dependent on HPLC measurement technique, which is a sample-destructive, labor-intensive, time-consuming, and expensive method. In this research, a nondestructive on-...

283

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

E-print Network

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

dos Santos, C.A.

284

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

285

Performance of TOF powder diffractometers on reactor sources  

NASA Astrophysics Data System (ADS)

In 1998, a prototype of a time-of-flight (TOF) powder diffractometer was built at KFKI in Budapest in collaboration with the Hahn-Meitner-Institut (HMI) in Berlin. At a reactor source the neutron pulses are produced by a chopper system, which allows for shorter pulses than those obtained at pulsed spallation sources in the wavelength range most relevant for diffraction work, i.e. ??0.7 . Furthermore, the chopper system provides an ideal symmetric line shape. First results proved the high potential of the approach, namely an excellent resolution of 1-510 -3 for ? d/d was achieved. The prototype is presently rebuilt as a user instrument at the Budapest Neutron Centre. At HMI Berlin a new much more complex TOF powder diffractometer (EXED=extreme environment diffractometer) with higher resolution is under construction. It will benefit from variable resolution to achieve either ultrahigh resolution or very high intensities at conventional resolutions. EXED is devoted to studies under extreme sample conditions, for instance the TOF technique permits the access of a broad range of Q-values or d-spacing domains under scattering angle access strongly restricted by the use of highest field magnets. The whole instrument was simulated by Monte Carlo (MC) technique, and the simulations yield promising results.

Peters, Judith; Bleif, Hans-J黵gen; Kali, Gy鰎gy; Rosta, Laszlo; Mezei, Ferenc

2006-11-01

286

Synthesis and properties of Sr2CeO4 blue emission powder phosphor for field emission displays  

NASA Astrophysics Data System (ADS)

A blue emission powder phosphor Sr2CeO4 for field emission displays was prepared using a chemical coprecipitation technique, which is most suitable for large-scale production. The powders were fired at different temperatures to optimize the properties. Firing the powder at 1200 癈 for 2 h gave the highest luminescence efficiency of 5.4 lm/W at 4 kV and 29.0 lm/W at 10 kV. The emission peak of this phosphor is at 470 nm and Commission International de l'Eclairage coordinates are x=0.19, y=0.26.

Jiang, Yong Dong; Zhang, Fuli; Summers, Christopher J.; Wang, Zhong Lin

1999-03-01

287

50 Omega characteristic impedance low-pass metal powder filters  

Microsoft Academic Search

We have fabricated several 50 Omega characteristic impedance low-pass metal powder filters. The filters are made with bronze or copper metal powder with varying amounts of metal powder in a metal powder\\/epoxy mixture. Our goal is to make a filter with a characteristic impedance Z=50 Omega at frequencies up to 10 GHz. Using a 78% bronze powder\\/epoxy mixture in a

F. P. Milliken; J. R. Rozen; G. A. Keefe; R. H. Koch

2007-01-01

288

50 ? characteristic impedance low-pass metal powder filters  

Microsoft Academic Search

We have fabricated several 50 ? characteristic impedance low-pass metal powder filters. The filters are made with bronze or copper metal powder with varying amounts of metal powder in a metal powder\\/epoxy mixture. Our goal is to make a filter with a characteristic impedance Z=50 ? at frequencies up to 10 GHz. Using a 78% bronze powder\\/epoxy mixture in a

F. P. Milliken; J. R Rozen; G. A. Keefe; R. H. Koch

2007-01-01

289

Slip casting nano-particle powders for making transparent ceramics  

DOEpatents

A method of making a transparent ceramic including the steps of providing nano-ceramic powders in a processed or unprocessed form, mixing the powders with de-ionized water, the step of mixing the powders with de-ionized water producing a slurry, sonifing the slurry to completely wet the powder and suspend the powder in the de-ionized water, separating very fine particles from the slurry, molding the slurry, and curing the slurry to produce the transparent ceramic.

Kuntz, Joshua D. (Livermore, CA); Soules, Thomas F. (Livermore, CA); Landingham, Richard Lee (Livermore, CA); Hollingsworth, Joel P. (Oakland, CA)

2011-04-12

290

Interaction between laser beam and powder stream in the process of laser cladding with powder feeding  

Microsoft Academic Search

Based on Lambert-Beer theorem and Mie's theory, the attenuation of laser power by a powder stream was calculated and the laser intensity distribution at the laser spot on the surface of a workpiece was obtained. Simultaneously, the temperature distribution of the powder particles arriving at different sites on the surface of the workpiece was computed following the heat equilibrium principle.

Yan-Lu Huang; Gong-Ying Liang; Jun-Yi Su; Jian-Guo Li

2005-01-01

291

Synthesis and characterizations of ball-milled nanocrystalline WC and nanocomposite WC朇o powders and subsequent consolidations  

Microsoft Academic Search

The room-temperature ball-milling technique has been successfully employed for fabrication of nanocrystalline powders of equiatomic WC by high-energy ball milling of elemental W and C powders. The progress of the solid state reaction has been monitored by means of X-ray diffraction, scanning electron microscopy and transmission electron microscopy (TEM). A complete single phase of hcp-WC was obtained after 295 ks

M. Sherif El-Eskandarany; Amir A Mahday; H. A Ahmed; A. H Amer

2000-01-01

292

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. 4 figs.

Flinn, J.E.; Korth, G.E.

1985-06-27

293

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

294

Inhaled Dry Powder Formulations for Treating Tuberculosis.  

PubMed

Tuberculosis is the second leading cause of death from infectious diseases. Although anti-tubercular drugs have been traditionally administered orally, there is a growing interest in delivering drugs via the pulmonary route using nebulisers or dry powder inhalers. Drugs in dry powder inhalers (DPI) are stable and DPI are user-friendly compared to nebulisation which is time consuming, inconvenient and inefficient and requires special equipment. For tuberculosis treatment, drugs should target alveolar macrophages that harbour microorganisms and/or maintain high drug concentration at the infection site in the lung. Drug particles include micro-particles or nanoparticles. Powders can be engineered by micronisation, crystallisation, spray drying, freeze drying and particle coating approaches. The formulation may contain single or combination drugs. This paper will provide an update on current status of TB, its pathogenesis, current treatment strategies, shortcomings of current oral or parenteral delivery strategies, pulmonary delivery devices, advantages of pulmonary delivery of powder formulations, formulation approaches and pharmacokinetic studies of pulmonary delivery of powders for inhalation. PMID:25030114

Das, Shyamal; Tucker, Ian; Stewart, Peter

2014-07-16

295

Identification and characterisation of thaumasite by XRPD techniques  

Microsoft Academic Search

X-ray powder diffraction (XRPD) data analysis techniques (full pattern fitting and Rietveld refinement) have been evaluated as a means of characterisation of thaumasite. For the first time, these XRPD methods, which employ the whole of the powder pattern rather than just a few reflections, have been used to study systems containing thaumasite. Structure refinement by Rietveld methods, using synchrotron data,

S. J. Barnett; C. D. Adam; A. R. W. Jackson; P. D. Hywel-Evans

1999-01-01

296

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

PubMed

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

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

2011-01-01

297

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

PubMed

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

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

2011-01-01

298

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

299

MnO spin-wave dispersion curves from neutron powder diffraction  

SciTech Connect

We describe a model-independent approach for the extraction of spin-wave dispersion curves from powder neutron total scattering data. Our approach is based on a statistical analysis of real-space spin configurations to calculate spin-dynamical quantities. The RMCPROFILE implementation of the reverse Monte Carlo refinement process is used to generate a large ensemble of supercell spin configurations from MnO powder diffraction data collected at 100 K. Our analysis of these configurations gives spin-wave dispersion curves for MnO that agree well with those determined independently using neutron triple-axis spectroscopic techniques.

Goodwin, Andrew L.; Dove, Martin T. [Department of Earth Sciences, Cambridge University, Downing Street, Cambridge CB2 3EQ (United Kingdom); Tucker, Matthew G. [ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire OX11 0QX (United Kingdom); Keen, David A. [ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire OX11 0QX (United Kingdom); Department of Physics, Oxford University, Clarendon Laboratory, Parks Road, Oxford OX1 3PU (United Kingdom)

2007-02-15

300

Physical properties of thorium oxalate powders and their influence on the thermal decomposition  

NASA Astrophysics Data System (ADS)

Thorium oxalate dihydrate powders were obtained by precipitation from thorium nitrate solution using oxalic acid in the presence of ultrasound and mechanical agitation. Properties measured included particle morphology, particle size and particle size distribution, and specific surface area. The thermal decompositions of the powders were investigated by using thermogravimetry and differential thermal analysis techniques. The result showed that the thermal decomposition stages of the thorium oxalate dihydrate obtained by mechanical and ultrasonic agitation are same. The decomposition reactions of the oxalates precipitated in the presence of ultrasound proceed in a narrower temperature interval, within a shorter period of time. The kinetic parameters for each stage were calculated.

Oktay, Enver; Yayli, Ahmet

2001-01-01

301

Preparation of nickel powders in nonaqueous media.  

NASA Astrophysics Data System (ADS)

Precipitation of nickel powder is usually carried out in aqueous media. Nonaqueous solvents such as ethanolamines offer several advantages. The effective temperature range extends to the higher temperatures needed for the reduction of nickel at atmospheric pressure, a reaction that is also facilitated by the basicity of the medium. Tests were carried out for the preparation of submicrometre nickel powders by the reduction of metal salts using various ethanolamines (monoethanolamine - MEA, diethanolamine - DEA, and triethanolamine - TEA) as solvents. Hydrazine (N2H4) was used as the reducing agent. The basicity, polarity, viscosity and boiling point of the reaction medium all affect the reactions. By changing the reaction conditions and the anionic component of the precursor salt, it was possible to alter the purity and morphology of the nickel powders obtained and the average particle size, except in the case of MEA where no reduction occured. The products were subsequently characterised by chemical analysis and by scanning electron microscopy.

Macek, Jadran; Degen, Andrej

302

Atomization methods for forming magnet powders  

DOEpatents

The invention encompasses methods of utilizing atomization, methods for forming magnet powders, methods for forming magnets, and methods for forming bonded magnets. The invention further encompasses methods for simulating atomization conditions. In one aspect, the invention includes an atomization method for forming a magnet powder comprising: a) forming a melt comprising R.sub.2.1 Q.sub.13.9 B.sub.1, Z and X, wherein R is a rare earth element; X is an element selected from the group consisting of carbon, nitrogen, oxygen and mixtures thereof; Q is an element selected from the group consisting of Fe, Co and mixtures thereof; and Z is an element selected from the group consisting of Ti, Zr, Hf and mixtures thereof; b) atomizing the melt to form generally spherical alloy powder granules having an internal structure comprising at least one of a substantially amorphous phase or a substantially nanocrystalline phase; and c) heat treating the alloy powder to increase an energy product of the alloy powder; after the heat treatment, the alloy powder comprising an energy product of at least 10 MGOe. In another aspect, the invention includes a magnet comprising R, Q, B, Z and X, wherein R is a rare earth element; X is an element selected from the group consisting of carbon, nitrogen, oxygen and mixtures thereof; Q is an element selected from the group consisting of Fe, Co and mixtures thereof; and Z is an element selected from the group consisting of Ti, Zr, Hf and mixtures thereof; the magnet comprising an internal structure comprising R.sub.2.1 Q.sub.13.9 B.sub.1.

Sellers, Charles H. (Idaho Falls, ID); Branagan, Daniel J. (Idaho Falls, ID); Hyde, Timothy A. (Idaho Falls, ID)

2000-01-01

303

Thermal, mechanical, electrical, linear and nonlinear optical properties of L-arginine dihydrofluoride single crystal  

NASA Astrophysics Data System (ADS)

L-arginine dihydrofluoride of dimensions upto 15109 mm 3 was successfully grown by slow evaporation technique from aqueous solution. The crystal was characterized by X-ray diffractometry, Elemental analysis, FT-IR, UV-Vis-NIR spectroscopy, thermal and microhardness studies. The dielectric constant and dielectric loss of the crystal were studied as function of frequency. Photoconductivity studies were also carried out on the sample. Kurtz powder SHG measurement confirms the NLO property of the grown crystals.

Sankar, D.; Menon, Vinay Raj; Sagayaraj, P.; Madhavan, J.

2010-01-01

304

Growth and characterization of L-Alanine-doped Zinc Thiourea Chloride single crystal (ZTC)  

Microsoft Academic Search

Single crystal of L-Alanine-doped Zinc Thiourea Chloride (ZTC) was grown by slow evaporation technique. L-Alanine was added in saturated ZTC solution by molar percent. The second-harmonic generation efficiency was studied by Kurtz and Perry powder SHG test for 1, 2, and 3 mole% L-Alanine-doped ZTC and compared with pure ZTC. We observed enhancement in the SHG efficiency of L-Alanine-doped ZTC.

N. R. Dhumane; S. S. Hussaini; V. G. Dongre; P. Ghugare; M. D. Shirsat

2009-01-01

305

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

306

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

307

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

308

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. 3 figs.

Salyer, I.O.

1995-12-26

309

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. 3 figures.

Salyer, I.O.

1994-12-06

310

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

311

" 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 慔umic acid' (HA), 慒ulvic 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 慣racer 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

312

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 慔umic acid' (HA), 慒ulvic 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 慣racer 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

313

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

314

Structural studies of magnesium nitride fluorides by powder neutron diffraction  

SciTech Connect

Samples of ternary nitride fluorides, Mg{sub 3}NF{sub 3} and Mg{sub 2}NF have been prepared by solid state reaction of Mg{sub 3}N{sub 2} and MgF{sub 2} at 1323-1423 K and investigated by powder X-ray and powder neutron diffraction techniques. Mg{sub 3}NF{sub 3} is cubic (space group: Pm3m) and has a structure related to rock-salt MgO, but with one cation site vacant. Mg{sub 2}NF is tetragonal (space group: I4{sub 1}/amd) and has an anti-LiFeO{sub 2} 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. - Graphical abstract: Definitive structures of the ternary magnesium nitride fluorides Mg{sub 3}NF{sub 3} and the lower temperature polymorph of Mg{sub 2}NF have been determined from powder neutron diffraction data. The nitride halides are essentially ionic and exhibit weak temperature independent paramagnetic behaviour. Highlights: Black-Right-Pointing-Pointer Definitive structures of Mg{sub 3}NF{sub 3} and Mg{sub 2}NF were determined by neutron diffraction. Black-Right-Pointing-Pointer Nitride and fluoride anions are crystallographically ordered in both structures. Black-Right-Pointing-Pointer Both compounds exhibit weak, temperature independent paramagnetic behaviour. Black-Right-Pointing-Pointer The compounds are essentially ionic with ionicity increasing with F{sup -} content.

Brogan, Michael A. [School of Chemistry, University of Nottingham, Nottingham NG7 2RD (United Kingdom); Hughes, Robert W. [WestCHEM, School of Chemistry, University of Glasgow, Glasgow G12 8QQ (United Kingdom); Smith, Ronald I. [ISIS Pulsed Neutron and Muon Source, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Oxford, Didcot OX11 0QX (United Kingdom); Gregory, Duncan H., E-mail: Duncan.Gregory@glasgow.ac.uk [WestCHEM, School of Chemistry, University of Glasgow, Glasgow G12 8QQ (United Kingdom)

2012-01-15

315

[Identification of pearl powder using microscopic infrared reflectance spectroscopy].  

PubMed

Pearl is a precious ornament and traditional Chinese medicine, which application history in China is more than 2000 years. It is well known that the chemical ingredients of shell and pearl are very similar, which all of them including calcium carbonate and various amino acids. Generally, shell powders also can be used as medicine; however, its medicinal value is much lower than that of pearl powders. Due to the feature similarity between pearl powders and shell powders, the distinguishment of them by detecting chemical composition and morphology is very difficult. It should be noted that shell powders have been often posing as pearl powders in markets, which seriously infringes the interests of consumers. Identification of pearl powder was investigated by microscopic infrared reflectance spectroscopy, and pearl powder as well as shell powder was calcined at different temperatures for different time before infrared reflectance spectroscopy analysis. The experimental results indicated that when calcined at 400 癈 for 30 minutes under atmospheric pressure, aragonite in pearl powder partly transformed into calcite, while aragonite in shell powder completely transformed into calcite. At the same time, the difference in phase transition between the pearl powders 'and shell powders can be easily detected by using the microscopic infrared reflectance spectroscopy. Therefore, based on the difference in their phase transition process, infrared reflectance spectroscopy can be used to identify phase transformation differences between pearl powder and shell powder. It's more meaningfully that the proposed infrared reflectance spec- troscopy method was also investigated for the applicability to other common counterfeits, such as oyster shell powders and abalone shell powders, and the results show that the method can be a simple, efficiently and accurately method for identification of pearl powder. PMID:25532338

Zhang, Xuan; Hu, Chao; Yan, Yan; Yang, Hai-Feng; Li, Jun-Fang; Bai, Hua; Xi, Guang-Cheng; Liao, Jie

2014-09-01

316

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

317

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

318

Thermal Conductivity of Powder Aggregates and Porous Compacts  

NASA Astrophysics Data System (ADS)

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

Montes, J. M.; Cuevas, F. G.; Cintas, J.; Mu駉z, S.

2012-12-01

319

Powder Reflection Spectroscopy in the Vacuum uv range  

NASA Astrophysics Data System (ADS)

The measurement of diffuse refl ectance spectra below 230 nm for ceramic luminescent materials is usually not performed although it is of tremendous interest, e.g., to determine their quantum effi ciency upon VUV excitation. In contrast, the recording of VUV excitation spectra is well established, e.g., to evaluate VUV phosphors. The lack of access to diffuse powder refl ection spectra in this range is caused by the absorption edge (optical band gap) of the most common refl ectance standards; for instance, BaSO4 or CaCO3-VUV photons with energies higher than the absorption edge are not refl ected but absorbed and thus not amenable to detection in a synchronous scan. The measurement technique presented in this paper allows monitoring refl ection properties of powder samples in the range from 120 to 300 nm (10.3 to 4.1 eV). To this end, all VUV photons refl ected by the sample are converted into visible photons, which are collected in an Ulbricht sphere and fi nally counted by a photomultiplier tube (PMT). This requires a custom-built integrating sphere, viz. one that is coated with a (V)UV to Vis converter, e.g., a phosphor such as BaMgAl10O17:Eu2+ (BAM:Eu) showing a spectrally independent and high light output in the respective wavelength range. This paper sketches the technique and procedure for recording VUV refl ection spectra and shows the results for several standard phosphors. It also reveals the limits of this new technique.

Enseling, D.; Herden, B.; Katelnikovas, A.; M鰈ler, S.; Winkler, H.; Petry, R.; Meyer, H.-J.; J黶tela, T.

2014-05-01

320

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

321

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

2012-09-15

322

Method for Pressing Powdered Explosives in Target Assemblies for Gas Gun-Driven Initiation Experiments  

NASA Astrophysics Data System (ADS)

In order to obtain an equation of state (EOS) and initiation information for a powdered explosive at the lower density ranges, it is necessary to press the material into the gas gun target assembly. Pressed pellets can be built into targets at the higher densities where they have physical integrity, but are difficult or impossible to handle at low densities. We have a need to employ the multiple magnetic gauge technique to measure the EOS and initiation data on low density, powdered explosives such as ammonium nitrate (AN). A "half cell" target assembly has been designed and built that has a magnetic gauge membrane glued to a triangular shaped cavity which can be loaded from the cell side. A pressing system has been built that uses a load cell to monitor the force exerted on a pressing stemple that fits into the triangular cavity. A force vs. density curve can be obtained for the particular powder and stemple/cell combination. Using this, the powdered explosive can be loaded to the desired density by pressing in increments to a given force. After the cell is loaded, a triangular plug is glued into the side to confine the sample. This paper describes the method of loading the cells with examples of pressing AN, and other powders into the target assemblies at different densities.

Stahl, David B.; Sheffield, Stephen A.; Dattelbaum, Dana M.

2009-12-01

323

Proton glass freezing in hydrated lysozyme powders  

Microsoft Academic Search

At room temperature, the dielectric relaxation of hydrated powder of the protein lysozyme is known to be due to protons migrating between ionized side chains. A recent study of this relaxation at lower temperatures suggested a behavior typical of proton glasses. An analysis of the complex dielectric susceptibility by a temperature-frequency plot presented here has revealed that ergodicity is broken

Adrijan Levstik; Cene Filipic; Zdravko Kutnjak; Giorgio Careri; Giuseppe Consolini; Fabio Bruni

1999-01-01

324

Balanced mechanical resonator for powder handling device  

NASA Technical Reports Server (NTRS)

A system incorporating a balanced mechanical resonator and a method for vibration of a sample composed of granular material to generate motion of a powder sample inside the sample holder for obtaining improved analysis statistics, without imparting vibration to the sample holder support.

Sarrazin, Philippe C. (Inventor); Brunner, Will M. (Inventor)

2012-01-01

325

Characterization of nal powders for rocket propulsion  

NASA Astrophysics Data System (ADS)

Nanosized metal powders are known to significantly improve both solid and hybrid rocket performance, but have some drawbacks in terms of cost, safety, and possible influence on propellant mechanical properties. Performance enhancement through nanosized metal or metal hydride addition to solid fuels is currently under investigation also for hybrid propulsion. Therefore, a preburning characterization of the powders used in solid propellant or fuel manufacturing is useful to assess their effects on the ballistic properties and engine performance. An investigation concerning the comparative characterization of several aluminum powders having different particle size, age, and coating is presented. Surface area, morphology, chemical species concentration and characteristics, surface passivation layers, surface and subsurface chemical composition, ignition temperature and ignition delay are investigated. The aim of this characterization is to experimentally assess the effect of the nAl powder properties on ballistic characteristics of solid fuels and solidrocket composite-propellant performance, showing an increase in terms of Is caused by the decrease of two-phase losses in solid and a possible significant rf increase in hybrid rockets.

Merotto, L.; Galfetti, L.; Colombo, G.; DeLuca, L. T.

2011-10-01

326

Low density fragile states in cohesive powders  

E-print Network

We discuss the difference between cohesive and non-cohesive granular media in the context of a recent report of "dry quicksand." Weak low density states with properties like dry quicksand are readily formed in common household powders. In contrast, such states cannot be formed in cohesionless granular media such as ordinary sand.

Paul B. Umbanhowar; Daniel I. Goldman

2005-12-24

327

Pressing behavior of atomized iron powders  

Microsoft Academic Search

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

A. F. Zhornyak; V. E. Oliker

1981-01-01

328

Sol-Gel Synthesis Of Aluminoborosilicate Powders  

NASA Technical Reports Server (NTRS)

Application of sol-gel process to synthesis of aluminoborosilicate powders shows potential for control of microstructures of materials. Development of materials having enhanced processing characteristics prove advantageous in extending high-temperature endurance of fibrous refractory composite insulation made from ceramic fibers.

Bull, Jeffrey; Leiser, Daniel; Selvaduray, Guna

1992-01-01

329

MODELING MERCURY CONTROL WITH POWDERED ACTIVATED CARBON  

EPA Science Inventory

The paper presents a mathematical model of total mercury removed from the flue gas at coal-fired plants equipped with powdered activated carbon (PAC) injection for Mercury control. The developed algorithms account for mercury removal by both existing equipment and an added PAC in...

330

Powder diffraction from solids in the terapascal regime  

SciTech Connect

A method of obtaining powder diffraction data on dynamically compressed solids has been implemented at the Jupiter and OMEGA laser facilities. Thin powdered samples are sandwiched between diamond plates and ramp compressed in the solid phase using a gradual increase in the drive-laser intensity. The pressure history in the sample is determined by back-propagation of the measured diamond free-surface velocity. A pulse of x rays is produced at the time of peak pressure by laser illumination of a thin Cu or Fe foil and collimated at the sample plane by a pinhole cut in a Ta substrate. The diffracted signal is recorded on x-ray sensitive material, with a typical d-spacing uncertainty of {approx}0.01 A. This diagnostic has been used up to 0.9 TPa (9 Mbar) to verify the solidity, measure the density, constrain the crystal structure, and evaluate the strain-induced texturing of a variety of compressed samples spanning atomic numbers from 6 (carbon) to 82 (lead). Further refinement of the technique will soon enable diffraction measurements in solid samples at pressures exceeding 1 TPa.

Rygg, J. R.; Eggert, J. H.; Lazicki, A. E.; Coppari, F.; Hawreliak, J. A.; Hicks, D. G.; Smith, R. F.; Uphaus, T. M.; Collins, G. W. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States); Sorce, C. M.; Yaakobi, B. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623 (United States)

2012-11-15

331

Improved Small-Particle Powders for Plasma Spraying  

NASA Technical Reports Server (NTRS)

Improved small-particle powders and powder-processing conditions have been developed for use in plasma spray deposition of thermal-barrier and environmental barrier coatings. Heretofore, plasma-sprayed coatings have typically ranged in thickness from 125 to 1,800 micrometers. As explained below, the improved powders make it possible to ensure complete coverage of substrates at unprecedently small thicknesses of the order of 25 micrometers. Plasma spraying involves feeding a powder into a hot, high-velocity plasma jet. The individual powder particles melt in the plasma jet as they are propelled towards a substrate, upon which they splat to build up a coating. In some cases, multiple coating layers are required. The size range of the powder particles necessarily dictates the minimum thickness of a coating layer needed to obtain uniform or complete coverage. Heretofore, powder particle sizes have typically ranged from 40 to 70 micrometers; as a result, the minimum thickness of a coating layer for complete coverage has been about 75 micrometers. In some applications, thinner coatings or thinner coating layers are desirable. In principle, one can reduce the minimum complete-coverage thickness of a layer by using smaller powder particles. However, until now, when powder particle sizes have been reduced, the powders have exhibited a tendency to cake, clogging powder feeder mechanisms and feed lines. Hence, the main problem is one of synthesizing smaller-particle powders having desirable flow properties. The problem is solved by use of a process that begins with a spray-drying subprocess to produce spherical powder particles having diameters of less than 30 micrometers. (Spherical-particle powders have the best flow properties.) The powder is then passed several times through a commercial sifter with a mesh to separate particles having diameters less than 15 micrometers. The resulting fine, flowable powder is passed through a commercial fluidized bed powder feeder into a plasma spray jet.

Nguyen, QuynhGiao, N.; Miller, Robert A.; Leissler, George W.

2005-01-01

332

Theory, manufacturing technology, and properties of powders and fibers  

Microsoft Academic Search

The properties of ferromagnetic powders after reduction annealing are examined. It is shown that magnetite and a destructured\\u000a composite organic coating ensure the resistance of such powders to external effects.

V. V. Nepomnyashchii; T. V. Mosina; A. K. Radchenko; G. Ya. Kalutskii

2007-01-01

333

Rheological and Thermal Debinding Behaviors in Titanium Powder Injection Molding  

NASA Astrophysics Data System (ADS)

Powder injection molding (PIM) is suitable for the fabrication of complex shape titanium and its alloys and has a great potential in many applications. This article deals with the injection molding of hydride-dehydride (HDH) titanium powder, spheroidized HDH titanium powder, and gas-atomized (GA) titanium powder. Rheological and thermal debinding behaviors are compared between feedstocks made from the three powders. Torque and capillary rheometers are used to investigate rheological behavior as it relates to the power-law model of viscosity and moldability index. Thermogravimetric analysis (TGA) was employed to analyze debinding behavior given a master decomposition curve consisting of two sigmoids. Spheroidized HDH Ti powder behaves in a manner similar to GA Ti powder. The analysis of the results in this study indicates the possibility of using a combination of HDH and GA titanium powders for PIM.

Park, Seong-Jin; Wu, Yunxin; Heaney, Donald F.; Zou, Xin; Gai, Guosheng; German, Randall M.

2009-01-01

334

Radio-absorbing properties of nickel-containing schungite powder  

NASA Astrophysics Data System (ADS)

A nickel-containing shungite powder has been synthesized by means of chemical reduction from aqueous solutions. The chemical composition and radio-absorbing properties of this powder have been studied.

Lyn'kov, L. M.; Borbot'ko, T. V.; Krishtopova, E. A.

2009-05-01

335

Charging Characteristics of Some Powders Used in Electrostatic Coating  

Microsoft Academic Search

Preliminary studies have been carried out on charging characteristics of two epoxy powders and a polytetrafluoroethylene (PTFE) by measuring charge-to-mass ratios (Q\\/m). The epoxy powders were charged by corona current and the PTFE by triboelectric. The results indicate that for the PTFE powder, the mean Q\\/m is inversely proportional to the particle radius, whereas for epoxy powders the pigmentation and

Sampuran Singh

1981-01-01

336

Influence of surface modification on wettability and surface energy characteristics of pharmaceutical excipient powders.  

PubMed

Influence of surface modification on wettability and surface energy characteristics of three micron size pharmaceutical excipient powders was studied using hydrophilic and hydrophobic grades of nano-silica. The wetting behavior assessed from contact angle measurements using sessile drop and liquid penetration (Washburn) methods revealed that both techniques showed similar wettability characteristics for all powders depending on the hydrophilic or hydrophobic nature of nano-coating achieved. The polar (?s(p)) and dispersive (?s(d)) components of surface energies determined using extended Fowke's equation with contact angle data from sessile drop method and inverse gas chromatography (IGC) at infinite dilution suggested a general trend of decrease in ?s(d) for all the surface modified powders due to passivation of most active sites on the surface. However, depending on the nature of the functional groups present in nano-silica, ?s(p) was found to be either higher or lower for hydrophilic or hydrophobic coating respectively. Results show that wettability increases with increasing ?s(p). Both the techniques of surface energy determination provided comparable and similar trends in ?s(p) and ?s(d) components of surface energies for all excipients. The study also successfully demonstrated that surface wettability and energetics of powders can be modified by varying the level of surface coating. PMID:25195729

Karde, Vikram; Ghoroi, Chinmay

2014-11-20

337

THERMAL CONDUCTIVITY OF POWDER INSULATIONS FOR CRYOGENIC STORAGE  

E-print Network

THERMAL CONDUCTIVITY OF POWDER INSULATIONS FOR CRYOGENIC STORAGE VESSELS Y. S. Choi1 '3 , M. N is measured in steady state, from which the thermal conductivity of powder insulation is calculated and compared with published results. KEYWORDS: Thermal conductivity, Powder insulations, Cryostats PACS:44

Chang, Ho-Myung

338

Oxidation of ultrafine (Si) SiC powders  

Microsoft Academic Search

The increasing usage of ultrafine ceramic powders in the fabrication of highly reliable ceramics results in a growing interest in appropriate processing conditions for these powders. During processing the extremely high surface areas might lead to significant absorbtion of oxygen even at low temperatures. But especially in this temperature regime, oxidation data of powders are rarely available; as far as

R. Vaben; D. St鰒er

1994-01-01

339

Critical thicknesses of electrostatic powder coatings from inside  

Microsoft Academic Search

A simple electrostatic model is applied to the charge powder coating of a grounded conductor eventually covered by insulating layers. The electric field inside the powder coating and its evolution during the process are established with also the corresponding evolution in the dielectric layer and some practical consequences are also discussed. The thickness of the charged powder layer is limited

Jacques Cazaux

2007-01-01

340

Cold forging of sintered iron-powder preforms  

Microsoft Academic Search

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

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

1995-01-01

341

Improved retort for cleaning metal powders with hydrogen  

NASA Technical Reports Server (NTRS)

Improved cleaning retort produces uniform temperature distribution in the heated zone and minimizes hydrogen channeling through the powder bed. Retort can be used for nonmetallic powders, sintering in a reducing atmosphere, and for cleaning powders in reduction atmospheres other than hydrogen.

Arias, A.

1969-01-01

342

Charge decay enhancement in polymer powders using plasma treatment  

Microsoft Academic Search

Slow charge decay characteristics of polymer powders results in occurrence of back corona which adversely affects the integrity of the powder film. The surface property that primarily governs the charge decay characteristics and back corona is the surface resistivity of the powder layer. Since the charge decay through these highly resistive polymers is primarily a surface phenomenon, surface modification was

R. Sharma; R. A. Sims; M. K. Mazumder

2002-01-01

343

Ignition of aluminum powders by electro-static discharge  

Microsoft Academic Search

Metal powder heating and ignition by an electro-static discharge, ESD (or spark) was investigated. For different spark voltages, ESD discharge energies transferred to the powder samples and respective spark radii are evaluated experimentally. Al powder was chosen as a popular metal fuel additive for many energetic formulations, and as a metal, for which spark initiation typically results in ignition of

Ervin Beloni; Edward L. Dreizin

2010-01-01

344

EPR Investigation of Irradiated Curry Powder  

SciTech Connect

Gamma-ray irradiated curry powder, a well priced oriental spice was investigated in order to establish the ability of EPR to detect the presence and time stability of free irradiation free-radicals. Accordingly, curry powder aliquots were irradiated with gradually increasing absorbed doses up to 11.3 kGy. The EPR spectra of all irradiated samples show the presence of al last two different species of free radicals, whose concentration increased monotonously with the absorbed doses. A 100 deg. C isothermal annealing of irradiated samples has shown a differential reduction of amplitude of various components of the initial spectra, but even after 3.6 h of thermal treatment, the remaining amplitude represents no less then 30% of the initial ones. The same peculiarities have been noticed after more than one year storage at room temperature, all of them being very useful in establishing the existence of any previous irradiation treatment.

Duliu, O. G.; Ali, S. I. [University of Bucharest, Department of Atomic and Nuclear Physics, P.O. Box MG-11, 077125 Bucharest (Romania); Georgescu, R. [National Institute for Physics and Nuclear Engineering-Horia Hulubei, P.O. Box MG-6, 077125 Bucharest (Romania)

2007-04-23

345

Dry powder mixes comprising phase change materials  

DOEpatents

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 in cementitious compositions of the type in which it is beneficial to use a PCM material. The silica-PCM mix can also be admixed with soil to provide a soil warming effect and placed about a tree, flower, or shrub. 2 figures.

Salyer, I.O.

1994-02-01

346

Dry powder mixes comprising phase change materials  

DOEpatents

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 in cementitious compositions of the type in which it is beneficial to use a PCM material. The silica-PCM mix can also be admixed with soil to provide a soil warming effect and placed about a tree, flower, or shrub.

Salyer, Ival O. (Dayton, OH)

1994-01-01

347

Dry powder mixes comprising phase change materials  

DOEpatents

Free flowing, conformable powder-like mix of silica particles and a phase change material (p.c.m.) is disclosed. The silica particles have a critical size of about 7.times.10.sup.-3 to about 7.times.10.sup.-2 microns and the pcm must be added to the silica in an amount of 80 wt. % 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 in cementitious compositions of the type in which it is beneficial to use a pcm material. The silica-pcm mix can also be admixed with soil to provide a soil warming effect and placed about a tree, flower, or shrub.

Salyer, Ival O. (Dayton, OH)

1993-01-01

348

Dry powder mixes comprising phase change materials  

DOEpatents

Free flowing, conformable powder-like mix of silica particles and a phase change material (p.c.m.) is disclosed. The silica particles have a critical size of about 7.times.10.sup.-3 to about 7.times.10.sup.-2 microns and the pcm must be added to the silica in an amount of 80 wt. % 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 in cementitious compositions of the type in which it is beneficial to use a pcm material. The silica-pcm mix can also be admixed with soil to provide a soil warming effect and placed about a tree, flower, or shrub.

Salyer, Ival O. (Dayton, OH)

1992-01-01

349

Dry powder mixes comprising phase change materials  

DOEpatents

Free flowing, conformable powder-like mix of silica particles and a phase change material (pcm) is disclosed. The silica particles have a critical size of about 7[times]10[sup [minus]3] to about 7[times]10[sup [minus]2] microns and the pcm must be added to the silica in an amount of 80 wt. % 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 in cementitious compositions of the type in which it is beneficial to use a pcm material. The silica-pcm mix can also be admixed with soil to provide a soil warming effect and placed about a tree, flower, or shrub. 10 figures.

Salyer, I.O.

1993-10-19

350

Dry powder mixes comprising phase change materials  

DOEpatents

Free flowing, conformable powder-like mix of silica particles and a phase change material (p.c.m.) is disclosed. The silica particles have a critical size of about 7.times.10.sup.-3 to about 7.times.10.sup.-2 microns and the pcm must be added to the silica in an amount of 80 wt. % or less pcm per combined weight of silica and pcm. The powder-like mix can be used in tableware items, medical wraps, tree wraps, garmets, quilts and blankets, and in cementitious compositions of the type in which it is beneficial to use a pcm material. The silica-pcm mix can also be admixed with soil to provide a soil warming effect and placed about a tree, flower, or shrub.

Salyer, Ival O. (Dayton, OH)

1993-01-01

351

Dry powder mixes comprising phase change materials  

DOEpatents

Free flowing, conformable powder-like mix of silica particles and a phase change material (p.c.m.) is disclosed. The silica particles have a critical size of about 7[times]10[sup [minus]3] to about 7[times]10[sup [minus]2] microns and the p.c.m. must be added to the silica in an amount of 80 wt. % or less p.c.m. per combined weight of silica and p.c.m. The powder-like mix can be used in tableware items, medical wraps, tree wraps, garments, quilts and blankets, and in cementitious compositions of the type in which it is beneficial to use a p.c.m. material. The silica-p.c.m. mix can also be admixed with soil to provide a soil warming effect and placed about a tree, flower, or shrub.

Salyer, I.O.

1993-05-18

352

Powder agglomeration in a microgravity environment  

NASA Technical Reports Server (NTRS)

This is the final report for NASA Grant NAG3-755 entitled 'Powder Agglomeration in a Microgravity Environment.' The research program included both two types of numerical models and two types of experiments. The numerical modeling included the use of Monte Carlo type simulations of agglomerate growth including hydrodynamic screening and molecular dynamics type simulations of the rearrangement of particles within an agglomerate under a gravitational field. Experiments included direct observation of the agglomeration of submicron alumina and indirect observation, using small angle light scattering, of the agglomeration of colloidal silica and aluminum monohydroxide. In the former class of experiments, the powders were constrained to move on a two-dimensional surface oriented to minimize the effect of gravity. In the latter, some experiments involved mixture of suspensions containing particles of opposite charge which resulted in agglomeration on a very short time scale relative to settling under gravity.

Cawley, James D.

1994-01-01

353

Powder Handling Device for Analytical Instruments  

NASA Technical Reports Server (NTRS)

Method and system for causing a powder sample in a sample holder to undergo at least one of three motions (vibration, rotation and translation) at a selected motion frequency in order to present several views of an individual grain of the sample. One or more measurements of diffraction, fluorescence, spectroscopic interaction, transmission, absorption and/or reflection can be made on the sample, using light in a selected wavelength region.

Sarrazin, Philippe C. (Inventor); Blake, David F. (Inventor)

2006-01-01

354

77 FR 20987 - Oral Dosage Form New Animal Drugs; Change of Sponsor; Lincomycin Hydrochloride Soluble Powder...  

Federal Register 2010, 2011, 2012, 2013

...Powder; Penicillin G Potassium in Drinking Water; Tetracycline Powder AGENCY...soluble powders administered in drinking water from Teva Animal Health, Inc...soluble powders administered in drinking water to Quo Vademus, LLC, 277...

2012-04-09

355

Full body powder antichip. Final report  

SciTech Connect

Chipping is the major paint defect listed for automobile customer dissatisfaction. The improved chip resistance and smoother paint surfaces produced by full body powder antichip will result in greater customer satisfaction and greater demand for US-produced automobiles. Powder antichip contains virtually no solvent, thereby reducing the potential VOC emissions from Newark Assembly by more than 90 tons per year as compared to the solvent-borne material presently applied in most full body applications. Since Newark Assembly Plant is in a severe non-attainment air quality area, which must demonstrate a 15% reduction in emissions by 1996, projects such as this are crucial to the longevity of industry in this region. The liquid paint spray systems include incineration of the oven volatile organic compounds (VOC`s) at 1,500 F. Since there are minimal VOC`s in powder coatings and the only possible releases occur only during polymerization, incineration is not required. The associated annual savings resulting from the elimination of the incinerator utilized on the liquid spray system is 1.44 {times} 10{sup 10} BTU`s per unit installed. The annual cost savings is approximately $388 thousand, far below the original estimates.

NONE

1996-04-17

356

Low-Flow-Rate Dry-Powder Feeder  

NASA Technical Reports Server (NTRS)

Apparatus feeds small, precise flow of dry powder through laser beam of optical analyzer measuring patterns of light created by forward scattering (Fraunhofer diffraction) of laser beam from powder particles. From this optical measurement, statistical distribution of sizes of powder particles computed. Rates of flow optimized for measurement of particle-size distributions. Developed for analyzing particle-size distributions of solid-propellant powders. Also adapted to pharmaceutical industry, in manufacture of metal powder, and in other applications where particle-size distributions of materials used to control rates of chemical reactions and/or physical characteristics of processes.

Ramsey, Keith E.

1994-01-01

357

Low-Flow-Rate Dry-Powder Feeder  

NASA Technical Reports Server (NTRS)

Apparatus feeds small, precise flow of dry powder through laser beam of optical analyzer, measuring patterns of light created by forward scattering (Fraunhofer diffraction) of laser beam from powder particles. From measurement, statistical distribution of sizes of powder particles computed. Developed for analyzing particle-size distributions of solid-propellant powders. Also adapted to use in pharmaceutical industry, in manufacture of metal powder, and in other applications in which particle-size distributions of materials used to control rates of chemical reactions and/or physical characteristics of processes.

Ramsey, Keith E.

1994-01-01

358

To evaluate the effect of various magnesium stearate polymorphs using powder rheology and thermal analysis.  

PubMed

The effects of magnesium stearate (MgSt) polymorphs-anhydrate (MgSt-A), monohydrate (MgSt-M), and dihydrate (MgSt-D)-on rheological properties of powders were evaluated using techniques such as atomic analysis and powder rheometry. Additional evaluation was conducted using thermal analysis, micromeritics, and tableting forces. In this study, binary ratios of neat MgSt polymorphs were employed as lubricants in powder blends containing acetaminophen (APAP), microcrystalline cellulose (MCC), and lactose monohydrate (LAC-M). Powder rheometry was studied using permeability, basic flow energy (BFE), density, and porosity analysis. Thermal conductivity and differential scanning calorimetric analysis of MgSt polymorphs were employed to elucidate MgSt effect on powder blends. The impact of MgSt polymorphs on compaction characteristics were analyzed via tablet compression forces. Finally, the distribution of atomized magnesium (Mg) ions as a function of intensity was evaluated using laser-induced breakdown spectroscopy (LIBS) on tablets. The results from LIBS analysis indicated the dependency of the MgSt polymorphic forms on the atomized Mg ion intensity, with higher Mg ion intensity suggesting higher lubricity index (i.e. greater propensity to over-lubricate). The results from lubricity index suggested the tendency of blends to over-lubricate based on the MgSt polymorphic forms. Finally, tableting forces suggested that MgSt-D and MgSt-A offered processing benefits such as lower ejection and compression forces, and that MgSt-M showed the most stable compression force in single or combined polymorphic ratios. These results suggested that the initial moisture content, crystal arrangement, intra- and inter-molecular packing of the polymorphs defined their effects on the rheology of lubricated powders. PMID:22304483

Okoye, Patrick; Wu, Stephen H; Dave, Rutesh H

2012-12-01

359

Incipient flow properties of two-component fine powder mixtures: Changing the flowability of smaller particles  

NASA Astrophysics Data System (ADS)

Understanding the flow properties of two-component fine powder systems with micrometre-sized constituents is important for the quality control of electrophotographic printing applications such as photocopiers. In previous work, we studied the incipient flow properties of model powder mixtures of large (d50 70 ?m) and small (d50 6-8 ?m) particles under a consolidation stress of 2 kPa, and reported that they were strongly related to the properties of the small particles where the volume ratio of small powder (xs) exceeds 0.1 [1]. In this follow-up study, we examine the effect of changing the flowability of the smaller components on the structure and flow properties of the binary mixtures. For the smaller particles, we used poly(styrene-co-divinylbenzene) (PS-DVB) microspheres (d50 = 7.84 ?m). The particle surfaces were modified by adding silica nanoparticles in order to prepare PS-DVB powders with a range of flowabilities. These were then mixed with glass ballotini (d50 = 71.9 ?m), and the flow properties of these mixtures were evaluated using the shear testing technique. The cohesion of the mixtures showed essentially the same trend as reported in [1] in terms of their dependence on xs and was related to the number of contacts between the PS-DVB particles. Also, it was strongly dependent on the cohesion of the PS-DVB powders despite a very small xs (xs < 0.01). As for the internal angle of friction, although its value for each PS-DVB powder was similar, it also showed a correlation with the number of contacts between PS-DVB particles.

Kojima, Takehiro; Elliott, James A.

2013-06-01

360

Experimental observations of dry powder inhaler dose fluidisation.  

PubMed

Dry powder inhalers (DPIs) are widely used to deliver respiratory medication as a fine powder. This study investigates the physical mechanism of DPI operation, assessing the effects of geometry, inhalation and powder type on dose fluidisation. Patient inhalation through an idealised DPI was simulated as a linearly increasing pressure drop across three powder dose reservoir geometries permitting an analysis of shear and normal forces on dose evacuation. Pressure drop gradients of 3.3, 10 and 30 kPa s(-1)were applied to four powder types (glass, aluminium, and lactose 6 and 16% fines) and high speed video of each powder dose fluidisation was recorded and quantitatively analysed. Two distinct mechanisms are identified, labelled 'fracture' and 'erosion'. 'Fracture' mode occurs when the initial evacuation occurs in several large agglomerates whilst 'erosion' mode occurs gradually, with successive layers being evacuated by the high speed gas flow at the bed/gas interface. The mechanism depends on the powder type, and is independent of the reservoir geometries or pressure drop gradients tested. Both lactose powders exhibit fracture characteristics, while aluminium and glass powders fluidise as an erosion. Further analysis of the four powder types by an annular shear cell showed that the fluidisation mechanism cannot be predicted using bulk powder properties. PMID:18457930

Tuley, Rob; Shrimpton, John; Jones, Matthew D; Price, Rob; Palmer, Mark; Prime, Dave

2008-06-24

361

Fabrication of Ag-Sheathed Bi2223 tapes using powders produced by aerosol spray pyrolysis  

Microsoft Academic Search

Bi-2223 tapes were manufactured from a fine 搕wo-powder product produced by using an aerosol spray pyrolysis technique. Critical\\u000a current density of 22000 A\\/ cm2 at 77K and 0 T was achieved. Nondestructive transmission x-ray diffraction study indicated\\u000a good alignment of the superconducting grains. The texturing process of the superconducting phase was found to be nearly complete\\u000a after the first 24

Yuan-Liang Wang; W. Bian; Y. Zhu; Y. Fukumoto; H. J. Wiesmann; M. Suenaga; T. R. Thurston; K. Merken; S. Hong

1995-01-01

362

Implementation and use of Robust Refinement in Powder Diffraction in the Presence of Impurities  

SciTech Connect

A modification to the usual least-squares analysis is implemented for the robust refinement of structural parameters from powder diffraction data in the presence of unmodeled impurities. This is accomplished in the program TOPAS-Academic by an iterative reweighting of the data as the model is refined. The method is tested and characterized using mixtures of known materials, acetaminophen and ibuprofen. The technique is also used to refine two previously unknown structures.

Stone, K.; Lapidus, S; Stephens, P

2009-01-01

363

Synthesis and magnetic properties of conventional and microwave calcined barium hexaferrite powder  

Microsoft Academic Search

Single phase nanoparticles of barium hexaferrite (BaFe12O19朆aF) were synthesized by sol杇el method using metal nitrates as source and d-Fructose as a fuel. The prepared precursors were calcined by two different calcination techniques, using conventional furnace\\u000a and microwave furnace. The samples are characterized using powder X-ray diffraction, theromogravimetric analysis and vibration\\u000a sample magnetometer. Thermal analysis studies showed exothermic and endothermic reaction

S. Kanagesan; S. Jesurani; R. Velmurugan; M. Sivakumar; C. Thirupathi; T. Kalaivani

364

Abrasive wear behaviour of hard powders filled glass fabric杄poxy hybrid composites  

Microsoft Academic Search

The effect of incorporation of tungsten carbide (WC) and tantalum niobium carbide (Ta\\/NbC) powders on three-body abrasive wear behaviour in glass fabric杄poxy (G朎) composites was investigated and findings are analysed. A vacuum assisted resin transfer moulding (VARTM) technique was employed to obtain a series of G朎 composites containing different fillers (WC and WC+Ta\\/NbC). Dry sand rubber wheel abrasion test was

N. Mohan; S. Natarajan; S. P. KumareshBabu

2011-01-01

365

Method for forming pyrrone molding powders and products of said method  

NASA Technical Reports Server (NTRS)

The formation of pyrrone resins of the ladder or semiladder structure is described. The technique involves initial formation of fully cyclized prepolymers having an average degree of polymerization of about 1.5, one with acidic terminal groups, another with amine terminal groups. Thereafter the prepolymers are intimately admixed on a 1:1 stoichiometric basis. The resulting powder mixture is molded at elevated pressures and temperatures to form a fully cyclized resin.

Hughes, C. T.; Mchenry, R. J. (inventors)

1972-01-01

366

Effects of sintered powder structural thickness on thin-film evaporation heat transfer at low superheat levels  

NASA Astrophysics Data System (ADS)

To investigate the correlation between thin-film evaporation heat transfer and structural thickness, this study develops a novel facility and method. The experiment reveals the effects of structural thickness at low superheat levels. The experimental results are integrated into figures for the thickness design of sintered powder structures in two-phase heat transfer devices. The facility includes features such as data acquisition at a high sampling rate, heat loss control, directly sintered specimens, stable environment pressure loops, and visualization techniques. Six types of powder were sintered, including powders 45 ?m, 75 ?m, and 150 ?m in diameter and spheral or dendritic powder shapes. The experimental results show that heat flux increases with increased superheat at low superheat levels with temperature differences lower than 6 癈. At the same superheat levels, heat flux decreases proportionally to the thicker thickness of the sintered powder structure in all six types of powder. Therefore, thicker structures increase thermal resistance, requiring a higher temperature difference to transfer the same amount of heat. Furthermore, thin-film evaporation occurs at a low level of superheat, which can dissipate heat at high heat density or during low levels of superheat.

Han Lee, Cho; Yang Tsai, Yao

2013-04-01

367

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

NASA Astrophysics Data System (ADS)

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. The effects of particle size and particle morphology on in-flight particle velocity and deposition efficiency were investigated. The critical velocity of copper powder was estimated by combining the in-flight particle velocity and deposition efficiency. The effect of annealing of feedstock powder on deposition and critical velocity was also investigated. The results showed that the irregular shape particle presents higher in-flight velocity than the spherical shape particle under the same condition. For irregular shape particles, the in-flight velocity decreased from 390 to 282 m/s as the particle size increases from 20 to 60 ?m. Critical velocities of about 425 m/s and more than 550 m/s were estimated for the feedstock copper powder with spherical and irregular shape morphology, respectively. For the irregular shape particles, the critical velocity decreased from more than 550 to 460 m/s after preheating at 390 癈 for 1 h. It was also found that the larger size powder presents a lower critical velocity in this study.

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

2007-07-01

368

Optimised process and formulation conditions for extended release dry polymer powder-coated pellets.  

PubMed

The objective of this study was to improve the film formation and permeability characteristics of extended release ethylcellulose coatings prepared by dry polymer powder coating for the release of drugs of varying solubility. Ethylcellulose (7 and 10 cp viscosity grades) and Eudragit(R) RS were used for dry powder coating of pellets in a fluidised bed ball coater. Pre-plasticised ethylcellulose powder was prepared by spray-drying aqueous ethylcellulose dispersions (Surelease(R) and Aquacoat(R)) or by hot melt extrusion/cryogenic grinding of plasticised ethylcellulose. Chlorpheniramine maleate and theophylline were used as model drugs of different solubilities. The film formation process, polymeric films and coated pellets were characterised by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), scanning electron microscopy (SEM) and dissolution testing. Film formation and extended drug release was achieved with ethylcellulose, a polymer with a high glass transition temperature (T(g)) without the use of water, which is usually required in dry powder coating. DMA-measurements revealed that plasticised ethylcellulose had a modulus of elasticity (E') similar to the low T(g) Eudragit(R) RS. With increasing plasticiser concentration, the T(g) of ethylcellulose was reduced and the mechanical properties improved, thus facilitating coalescence of the polymer particles. SEM-pictures revealed the formation of a dense, homogeneous film. The lower viscosity grade ethylcellulose (7 cp) resulted in better film formation than the higher viscosity grade (10 cp) and required less stringent curing conditions. Successful extended release ethylcellulose coatings were also obtained by coating with pre-plasticised spray-dried ethylcellulose powders as an alternative to the separate application of pure ethylcellulose powder and plasticiser. The permeability of the extended release coating could be controlled by using powder blends of ethylcellulose with the hydrophilic polymer HPMC. In conclusion, dry polymer powder coating is an interesting technique to achieve extended release of drugs with varying solubility as an alternative to classical coatings obtained from organic polymer solution or aqueous polymer dispersions. PMID:20079833

Terebesi, Ildik; Bodmeier, Roland

2010-05-01

369

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

NASA Astrophysics Data System (ADS)

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

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

2000-05-01

370

A Dry Powder Process for Preparing Uni-Tape Prepreg from Polymer Powder Coated Filamentary Towpregs  

NASA Technical Reports Server (NTRS)

A process for preparing uni-tape prepreg from polymer powder coated filamentary towpregs is provided. A plurality of polymer powder coated filamentary towpregs are provided. The towpregs are collimated so that each towpreg is parallel. The sandwich is heated to a temperature wherein the polymer flows and intimately contacts the filaments and pressure is repeatedly applied perpendicularly to the sandwich with a longitudinal oscillating action wherein the filaments move apart and the polymer wets the filaments forming a uni-tape prepreg. The uni-tape prepreg is subsequently cooled.

Wilkinson, Steven P. (inventor); Johnston, Norman J. (inventor); Marchello, Joseph M. (inventor)

1995-01-01

371

Dry powder process for preparing uni-tape prepreg from polymer powder coated filamentary towpregs  

NASA Technical Reports Server (NTRS)

A process for preparing uni-tape prepreg from polymer powder coated filamentary towpregs is provided. A plurality of polymer powder coated filamentary towpregs are provided. The towpregs are collimated so that each towpreg is parallel. A material is applied to each side of the towpreg to form a sandwich. The sandwich is heated to a temperature wherein the polymer flows and intimately contacts the filaments and pressure is repeatedly applied perpendicularly to the sandwich with a longitudinal oscillating action wherein the filaments move apart and the polymer wets the filaments forming a uni-tape prepreg. The uni-tape prepreg is subsequently cooled.

Wilkinson, Steven P. (Inventor); Johnston, Norman J. (Inventor); Marchello, Joseph M. (Inventor)

1997-01-01

372

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

SciTech Connect

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

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

2012-01-01

373

Agglomerate behaviour of fluticasone propionate within dry powder inhaler formulations.  

PubMed

Due to their small size, the respirable drug particles tend to form agglomerates which prevent flowing and aerosolisation. A carrier is used to be mixed with drug in one hand to facilitate the powder flow during manufacturing, in other hand to help the fluidisation upon patient inhalation. Depending on drug concentration, drug agglomerates can be formed in the mixture. The aim of this work was to study the agglomeration behaviour of fluticasone propionate (FP) within interactive mixtures for inhalation. The agglomerate phenomenon of fluticasone propionate after mixing with different fractions of lactose without fine particles of lactose (smaller than 32 ?m) was demonstrated by the optical microscopy observation. A technique measuring the FP size in the mixture was developed, based on laser diffraction method. The FP agglomerate sizes were found to be in a linear correlation with the pore size of the carrier powder bed (R(2)=0.9382). The latter depends on the particle size distribution of carrier. This founding can explain the role of carrier size in de-agglomeration of drug particles in the mixture. Furthermore, it gives more structural information of interactive mixture for inhalation that can be used in the investigation of aerosolisation mechanism of powder. According to the manufacturing history, different batches of FP show different agglomeration intensities which can be detected by Spraytec, a new laser diffraction method for measuring aerodynamic size. After mixing with a carrier, Lactohale LH200, the most cohesive batch of FP, generates a lower fine particle fraction. It can be explained by the fact that agglomerates of fluticasone propionate with very large size was detected in the mixtures. By using silica-gel beads as ball-milling agent during the mixing process, the FP agglomerate size decreases accordingly to the quantity of mixing aid. The homogeneity and the aerodynamic performance of the mixtures are improved. The mixing aid based on ball-milling effect could be used to ameliorate the quality of inhalation mixture of cohesive drug, such as fluticasone propionate. However, there is a threshold where an optimal amount of mixing aids should be used. Not only the drug des-aggregation reaches its peak but the increase in drug-carrier adhesion due to high energy input should balance the de-agglomeration capacity of mixing process. This approach provides a potential alternative in DPI formulation processing. PMID:22198291

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

2012-04-01

374

The effect of chromating on borohydride reduced iron powders  

NASA Astrophysics Data System (ADS)

Iron powders with Hc between 350 Oe and 1000 Oe were prepared by borohydride reduction of ferrous sulfate. The powders were stabilized by a chromating procedure. This paper discusses the effect of the chromating as observed by: TEM, changes in surface area, O2 content, ESCA/Auger and adsorption. Chromating coats the surface of the particles with a layer of FeCr2O4. Oxygen content in chromated powders is generally 8% while in the unchromated powders, it varies between 11 and ?16%. This increase in O2 can be correlated with a decrease in ?s. Sheet-like impurities are observed in unchromated powders which have been identified as FeOOH. Chromating results in a reduction in surface area of the particles as measured by N2 adsorption. The stability of the powders is greatly improved with chromating. Powders subjected to 80% R.H. for 112 days showed that the unchromated powder lost 25% of its original magnetization, while the chromated powder lost only 3%. Simultaneously, a band of FeO and Fe2O3 formed around the particles. Adsorption studies of reference polymers have shown that chromating reduces the acidic surface sites of the powders.

Baltz, A.; Freitag, W. O.; Greifer, A. P.; Suchodolski, V.

1981-03-01

375

Processing of laser formed SiC powder  

NASA Technical Reports Server (NTRS)

Superior SiC characteristics can be achieved through the use of ideal constituent powders and careful post-synthesis processing steps. High purity SiC powders of approx. 1000 A uniform diameter, nonagglomerated and spherical were produced. This required major revision of the particle formation and growth model from one based on classical nucleation and growth to one based on collision and coalescence of Si particles followed by their carburization. Dispersions based on pure organic solvents as well as steric stabilization were investigated. Although stable dispersions were formed by both, subsequent part fabrication emphasized the pure solvents since fewer problems with drying and residuals of the high purity particles were anticipated. Test parts were made by the colloidal pressing technique; both liquid filtration and consolidation (rearrangement) stages were modeled. Green densities corresponding to a random close packed structure (approx. 63%) were achieved; this highly perfect structure has a high, uniform coordination number (greater than 11) approaching the quality of an ordered structure without introducing domain boundary effects. After drying, parts were densified at temperatures ranging from 1800 to 2100 C. Optimum densification temperatures will probably be in the 1900 to 2000 C range based on these preliminary results which showed that 2050 C samples had experienced substantial grain growth. Although overfired, the 2050 C samples exhibited excellent mechanical properties. Biaxial tensile strengths up to 714 MPa and Vickers hardness values of 2430 kg/sq mm 2 were both more typical of hot pressed than sintered SiC. Both result from the absence of large defects and the confinement of residual porosity (less than 2.5%) to small diameter, uniformly distributed pores.

Haggerty, J. S.; Bowen, H. K.

1985-01-01

376

Solid-state {sup 29}Si NMR analysis of amorphous silicon nitride powder  

SciTech Connect

Solid-state {sup 29}Si NMR techniques were used to characterize laser-synthesized silicon nitride powder prepared from the reaction of silane with ammonia. When the powder is exposed to water vapor, a hydrated layer rapidly forms at the surface. A comparison of {sup 29}Si cross polarization (CP) and Bloch decay (BD)-MAS-NMR spectra revealed differences between surface and bulk compositions. CP-NMR identified Si-NH{sub x} (x = 1, 2) species with a chemical shift of {minus}45 ppm in the as-synthesized (unexposed) powder. In BD-NMR spectra, the nitride resonance is observed at {minus}48 ppm. For the hydrated powder, CP-NMR identified additional {triple_bond}Si-OH (Q{sup 3}), {double_bond}Si-(OH){sub 2} (Q{sup 2}), and SiO{sub 2} (Q{sup 4}) species present at the surface. The CP-NMR spectra were corrected for T{sub 1pH} relaxation effects and deconvoluted into individual components in order to extract quantitative measurements of the various species present.

Leone, E.A.; Curran, S.; Kotun, M.E. [AlliedSignal Inc., Morristown, NJ (United States); Carrasquillo, G.; Weeren, R. van; Danforth, S.C. [Rutgers-the State Univ., Piscataway, NJ (United States). Center for Ceramic Research

1996-02-01

377

Structural and spectroscopic analyses of europium doped yttrium oxyfluoride powders prepared by combustion synthesis  

SciTech Connect

A facile widely spread technique employed to produce low-cost high-yield oxide powders, combustion synthesis, was used to prepare yttrium oxyfluoride crystalline ceramic powders. The structure of the powders was analyzed by X-ray powder diffraction and Rietveld refinement. Samples heat treated at 700 癈 had a predominance of vernier orthorhombic Y{sub 6}O{sub 5}F{sub 8} phase, while samples heat treated at 800 癈 crystallized in stoichiometric rhombohedral YOF phase. The samples were doped with luminescent europium trivalent ions (Eu{sup 3+}) in different concentrations (115 wt.%) and Judd-Ofelt theory was used to probe the distortion from the inversion symmetry of the local crystal field and the degree of covalency between the rare-earth ion and the surrounding ligands. The luminescence lifetime was measured and the luminescence quantum efficiency (LQE) was estimated. We observed that Eu{sup 3+}:Y{sub 6}O{sub 5}F{sub 8} samples presented higher LQE in spite of the larger local crystal field anisotropy found for Eu{sup 3+}:YOF samples.

Rakov, Nikifor [PG-Ci阯cia dos Materiais, Universidade Federal do Vale do S鉶 Francisco, 48902-300 Juazeiro, BA (Brazil)] [PG-Ci阯cia dos Materiais, Universidade Federal do Vale do S鉶 Francisco, 48902-300 Juazeiro, BA (Brazil); Guimar鉫s, R. B.; Maciel, Glauco S. [Instituto de F韘ica, Universidade Federal Fluminense, 24210-346 Niter骾, RJ (Brazil)] [Instituto de F韘ica, Universidade Federal Fluminense, 24210-346 Niter骾, RJ (Brazil); Lozano B, W. [Departamento de F韘ica, Universidade Federal de Pernambuco, 50670-901 Recife, PE (Brazil)] [Departamento de F韘ica, Universidade Federal de Pernambuco, 50670-901 Recife, PE (Brazil)

2013-07-28

378

Adhesion forces in interactive mixtures for dry powder inhalers--evaluation of a new measuring method.  

PubMed

Dry powder inhalers mostly contain carrier based formulations where micronized drug particles are adhered to coarse carrier particles. The performance of the dry powder inhaler depends on the inhaler device, the inhalation manoeuvre and the formulation. The most important factor influencing the behaviour of the formulation is the adhesion force acting between the active ingredient and the carrier particles, which can be measured using different methods, for example the centrifuge technique or atomic force microscopy. In this study the tensile strength method, usually applied to determine cohesion forces between powder particles of one material, is optimized for adhesion force measurements between powder particles of unlike materials. Adhesion force measurements between the carrier materials lactose or mannitol and the drug substance salbutamol sulphate using the tensile strength method and the atomic force microscopy show higher values with increasing relative humidity. Consequently, the fine particle fraction determined using the Next Generation Impactor decreases with increasing relative humidity as a result of the enhanced interparticle interactions. PMID:17418548

Lohrmann, Maike; Kappl, Michael; Butt, Hans-Juergen; Urbanetz, Nora Anne; Lippold, Bernhard Christian

2007-09-01

379

Persistent inguinal seroma managed with sprinkling of talcum powder: a case report  

PubMed Central

Introduction We present a new method to treat recurrent seromas, which is based on our experience with a patient who had recurrent groin seroma and was treated successfully with a sprinkling of talcum powder in the seroma cavity. Case presentation A 67-year-old Caucasian man with a suprapubic recurrent right groin hernia underwent inguinal hernioplasty with a polypropylene plug. Three days later the patient presented with a right groin fluctuating mass beneath the surgical wound with no signs of infection, and was discharged after seroma aspiration. After 23 days of increasing drainage, the seroma cavity was thoroughly dried with clean gauze swabs, and four g of sterilized dry talcum powder was sprinkled into the seroma cavity with a five-cc syringe. A compressive dressing was placed, and the patient was discharged. One week after the sprinkling of talcum powder, the surgical wound was almost closed with only minimal oozing from the drainage incision. The patient did not report any adverse effects. Two weeks later, the wound was fully healed. Conclusion Talcum powder sprinkling could be an effective, quick, and safe method for the treatment of inguinal seromas after inguinal hernioplasty when conservative management has failed. Nevertheless, larger series are needed before assessing this technique as the treatment of choice. PMID:23171541

2012-01-01

380

Method for pressing powdered explosives in target assemblies for gas gun-driven initiation experiments  

NASA Astrophysics Data System (ADS)

In order to obtain an equation of state (EOS) and initiation information for a powdered explosive at the lower density ranges, it is necessary to press the material into the gas gun target assembly. Pressed pellets can be built into targets at the higher densities where they have integrity or can be machined but are difficult or impossible to use at low densities. We have a need to employ multiple magnetic gauges to measure the EOS and initiation data on low density, powdered explosives such as ammonium nitrate (AN). We have designed a ``half cell'' target assembly that has a magnetic gauge membrane glued to a triangular shaped cavity which can be loaded from the cell side. The technique uses a miniature load cell to monitor the force on a pressing stemple that fits into the triangular cavity. A force vs. density curve can be obtained for the particular powder and stemple/cell combination. Using this, the powdered explosive can be loaded to the desired density by pressing in increments to a given force. After the cell is loaded, a cover is glued on to confine the sample. Examples of pressing AN into the target assemblies at different densities and the data obtained from the gas gun driven experiments will be shown.

Stahl, David B.; Sheffield, Stephen A.; Dattelbaum, Dana M.

2009-06-01

381

Explosively generated shock wave processing of metal powders by instrumented detonics  

NASA Astrophysics Data System (ADS)

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

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

2013-06-01

382

An Experimental Study on the Fabrication of Glass-based Acceleration Sensor Body Using Micro Powder Blasting Method  

Microsoft Academic Search

This study investigated the feasibility of the micr o powder blasting technique for the micro fabrication of sensor structures using th e Pyrex glass to replace the existing silicon-based acceleration sensor fabrication proce sses. As the preliminary experiments, the effects of the blasting pressure, the mass flow rat e of abrasive and the number of nozzle scanning times on erosion

Dong-Sam Park; Dae-Jin Yun; Myeong-Woo Cho; Bong-Cheol Shin

2007-01-01

383

LaRC powder prepreg system  

SciTech Connect

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 and operating correlations have been developed to provide the basis for scale up to commercial operation. Special features of the operation are the pneumatic tow spreader, fluidized bed and resin feed systems.

Baucom, R.M.; Marchello, J.M. (NASA Langley Research Center, Hampton, VA (USA))

1990-07-01

384

Powder and particulate production of metallic alloys  

NASA Technical Reports Server (NTRS)

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

Grant, N. J.

1982-01-01

385

Microwave characterisation of carbon nanotube powders  

PubMed Central

We have used a 3-GHz microwave host cavity to study the remarkable electronic properties of metallic, single-walled carbon nanotubes. Powder samples are placed in its magnetic field antinode, which induces microwave currents without the need for electrical contacts. Samples are shown to screen effectively the microwave magnetic field, implying an extremely low value of sheet resistance (< 10 ??) within the graphene sheets making up the curved nanotube walls. Associated microwave losses are large due to the large surface area, and also point to a similar, very small value of sheet resistance due to the inherent ballistic electron transport. PMID:22849959

2012-01-01

386

Scalable synthesis of nanoporous palladium powders.  

SciTech Connect

Nanoporous palladium powders are synthesized on milligram to gram scales by chemical reduction of tetrachloro complexes by ascorbate in a concentrated aqueous surfactant at temperatures between -20 and 30 C. Particle diameters are approximately 50 nm, and each particle is perforated by 3 nm pores, as determined by electron tomography. These materials are of potential value for storage of hydrogen isotopes and electrical charge; producing them at large scales in a safe and efficient manner will help realize this. A slightly modified procedure also results in nanoporous platinum.

Robinson, David B.; Tran, Kim L.; Clift, W. Miles; Arslan Ilke; Langham, Mary Elizabeth; Ong, Markus D.; Fares, Stephen James

2009-03-01

387

A protocol for the classification of powder compression characteristics.  

PubMed

In this paper, a structured protocol for powder compression analysis as a test to assess the mechanical properties of particles in a formulation development programme is presented. First, the sequence of classification steps of the protocol is described, and secondly, the protocol is illustrated using compression data of six powders of two model substances, sodium chloride and mannitol. From powder compression data, a set of compression variables are derived, and by using critical values of these variables, the stages expressed during the compression of the powders are identified and the powders are classified into groups with respect to the expression of particle rearrangement, particle fragmentation and particle plastic deformation during compression. It is concluded that the proposed protocol could, in a satisfactorily way, describe and distinguish between the powders regarding their compression behaviour. Hence, the protocol could be a valuable tool for the formulation scientist to comprehensively assess important functionality-related characteristics of drugs and excipients. PMID:21946474

Nordstr鰉, Josefina; Klevan, Ingvild; Alderborn, G鰎an

2012-01-01

388

Printed circuit board metal powder filters for low electron temperatures  

NASA Astrophysics Data System (ADS)

We report the characterisation of printed circuit boards (PCB) metal powder filters and their influence on the effective electron temperature which is as low as 22 mK for a quantum dot in a silicon MOSFET structure in a dilution refrigerator. We investigate the attenuation behaviour (10 MHz-20 GHz) of filter made of four metal powders with a grain size below 50 ?m. The room-temperature attenuation of a stainless steel powder filter is more than 80 dB at frequencies above 1.5 GHz. In all metal powder filters, the attenuation increases with temperature. Compared to classical powder filters, the design presented here is much less laborious to fabricate and specifically the copper powder PCB-filters deliver an equal or even better performance than their classical counterparts.

Mueller, Filipp; Schouten, Raymond N.; Brauns, Matthias; Gang, Tian; Lim, Wee Han; Lai, Nai Shyan; Dzurak, Andrew S.; van der Wiel, Wilfred G.; Zwanenburg, Floris A.

2013-04-01

389

HVOF Combustion spraying of inconel powder  

NASA Astrophysics Data System (ADS)

A major trend in the thermal spray industry has been to increase the gas jet velocity to obtain better coating attributes. One emerging technology now used in industry is the high-velocity oxygen fuel process (HVOF). High-velocity spray guns combine oxygen and a fuel gas to generate heat and extremely high particle velocities. In this study, Inconel 718 powder was deposited on steel substrates. The primary coating function was electrical resistivity for a heater application. Experiments were conducted using a Taguchi L8 statistical fractional/factorial design parametric study. The Taguchi experiment evaluated the effect of six HVOF processing variables on the measured responses. The parameters were oxygen flow, fuel flow, air envelope gas flow, powder feed rate, spray distance, and nozzle configuration. The coatings were characterized by hardness tests, surface profilometry, optical metallography, and image analysis. This article investigates coating hardness, porosity, surface roughness, deposition efficiency, and microstructure with respect to the influence of the processing parameters. Analytical studies were conducted to investigate gas, particle, and coating dynamics for two of the HVOF thermal spray experiments.

Varacalle, D. J.; Ortiz, M. G.; Miller, C. S.; Steeper, T. J.; Rotolico, A. J.; Nerz, J.; Rlggs, W. L.

1993-06-01

390

Detonation synthesis of nanosized titanium dioxide powders  

NASA Astrophysics Data System (ADS)

Utilizing titanyl sulfate as a TiO2 source, via a novel synthesis method梩he detonation method梟anosized TiO2(n-TiO2) powders were prepared. The results showed that the as-prepared n-TiO2 powders did not have enough time to grow into large and fine crystallites, and that the characteristics of high temperature, high pressure and high cooling were helpful in the synthesis of nanosized materials. The anatase phase appeared to be the stable form of nanocrystalline TiO2 at small crystallite sizes to some extent and part of the rutile phase could transform to the anatase phase when the detonation products were oxidized to eliminate the impurities via the combined action of chromic anhydride (CrO3) and concentrated nitric acid. The main reason resulting in the reversal of stability of anatase and rutile could be the differences in the surface energy of anatase and rutile at small crystallite sizes.

Qu, Yandong; Li, Xiaojie; Wang, Xiaohong; Liu, Dahui

2007-05-01

391

Oxidation and dissolution of tungsten carbide powder in water  

Microsoft Academic Search

The oxidation and dissolution of tungsten carbide powder dispersed in water was investigated using X-ray photoelectron spectroscopy (XPS) and leaching studies. We found that the WO3 surface layer on the oxidised tungsten carbide powder dissolves readily at pH>3 with the tungsten concentration increasing linearly with time. Adding cobalt powder to the tungsten carbide suspension resulted in a significant reduction of

Karin M. Andersson; Lennart Bergstr鰉

2000-01-01

392

Mach stem characterization in Mbar designs using RSR powder  

SciTech Connect

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

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

1985-01-01

393

The biaxial loading response of powder aluminum at elevated temperature  

Microsoft Academic Search

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

T. O. Woods; D. G. Berghaus

1994-01-01

394

Preparation and surface properties of encapsulated powder pharmaceuticals  

Microsoft Academic Search

During the blending of two powders in a mixer, the preferential adhesion and sticking of fine powders onto other large powder\\u000a surfaces were usually observed. These frictional charging and physical adhesiveness properties can be used to modify and encapsulate\\u000a the surfaces of solids. In the present study, a centrifugal rotating-type mixer was used to study the possible wax encapsulation\\u000a process

Masumi Koishi; Takafumi Ishizaka; Takehisa Nakajima

1984-01-01

395

In situ characterization of small-particle plasma sprayed powders  

Microsoft Academic Search

The effect of various small-particle plasma spray powder injection parameters on the in situ particle position, velocity,\\u000a and temperature is measured for yttria-stabilized zirconia and yttrium-aluminum-garnet powder. Using full-factorial experiments\\u000a and multiple regression analysis, carrier gas flow, injector angle, and powder feeder disc speed were found to significantly\\u000a affect the particle properties. Temperature and velocity were inversely related; on average,

Y. J. Su; K. T. Faber; T. F. Bernecki

2002-01-01

396

Microstructure of composite material with powders of barium ferrite  

Microsoft Academic Search

Purpose: The aim of the present work is the microstructure characterization of commercial powder BaFe12O19 (as-prepared) and composite material with BaFe12O19 powders and polymer matrix, using XRD (X-Ray Diffraction) and SEM (Scanning Electron Microscopy) methods. Design\\/methodology\\/approach: The morphology of barium ferrite powders and a fracture surface of the examined composite material was realized by using the scanning electron microscope. The

R. Nowosielski; R. Babilas; G. Dercz; L. Paj?k b

397

Nanograin formation in milled MoO3 powders  

NASA Astrophysics Data System (ADS)

Powder of Molybdenum trioxide was milled for different times in horizontal ball mills. Such powder was characterized by TEM and XRD. Powder was rapidly de-agglomerated and fragmented up to attain nanoplates of two types, amorphous and crystalline. Finally, cold-welding of nanoplates occurred permitting some relaxation process to obtain a more stable energized structure consisting of equiaxial crystalline nanograins after 16 hours of milling.

Guerrero-Paz, J.; Dorantes-Rosales, H.; Aguilar-Mart韓ez, J. A.; Garibay-Febles, V.

2013-06-01

398

Superior tribological properties of powder materials with solid lubricant nanoparticles  

Microsoft Academic Search

Friction and wear of powder materials impregnated with commercially available layered (platelets) WS2 (2H) and inorganic fullerene-like WS2 nanoparticles (IF) were studied. Bronze杇raphite, iron杇raphite and iron杗ickel杇raphite samples were used in this experiment. The linear wear of powder materials (in situ) was measured. It was shown that the IF nanoparticles impregnated into the pores improve the tribological properties of powder materials

L Rapoport; V Leshchinsky; M Lvovsky; I Lapsker; Yu Volovik; Y Feldman; R Popovitz-Biro; R Tenne

2003-01-01

399

Structural changes during milling of aluminum oxide powders  

NASA Technical Reports Server (NTRS)

The mechanical activation of four fused corundum powders and a calcined Al2O3 powder was studied. The milled powders were characterized by their structural properties, crystallite size, and lattice distortions. Structural changes during milling, detected by X-ray line broadening analysis, gave information about the enhanced activity of the powders caused by the lattice distortions and by the decreasing crystallite size during milling. The structural changes during milling, under the same milling conditions, can be quite different for the same ceramic material, but with different characteristics in the as received state.

Ziepler, G.

1984-01-01

400

Forming gas treatment of lithium ion battery anode graphite powders  

DOEpatents

The invention provides a method of making a battery anode in which a quantity of graphite powder is provided. The temperature of the graphite powder is raised from a starting temperature to a first temperature between 1000 and 2000.degree. C. during a first heating period. The graphite powder is then cooled to a final temperature during a cool down period. The graphite powder is contacted with a forming gas during at least one of the first heating period and the cool down period. The forming gas includes H.sub.2 and an inert gas.

Contescu, Cristian Ion; Gallego, Nidia C; Howe, Jane Y; Meyer, III, Harry M; Payzant, Edward Andrew; Wood, III, David L; Yoon, Sang Young

2014-09-16

401

Process for synthesizing compounds from elemental powders and product  

DOEpatents

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

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

1993-01-01

402

Biodegradation of thermoplastic starch/eggshell powder composites.  

PubMed

Thermoplastic starch (TPS) was prepared using compression molding and chicken eggshell was used as a filler. The effect of the eggshell powder (EP) on the properties of TPS was compared with the effect of commercial calcium carbonate (CC). The organic compound on the surface of the eggshell powder acted as a coupling agent that resulted in a strong adhesion between the eggshell powder and the TPS matrix, as confirmed by SEM micrographs. The biodegradation was determined by the soil burial test. The TPS/EP composites were more rapidly degraded than the TPS/CC composites. In addition, the eggshell powder improved the water resistance and thermal stability of the TPS. PMID:23911451

Bootklad, Munlika; Kaewtatip, Kaewta

2013-09-12

403

Powder processing of nickel and other aluminides by hot consolidation  

NASA Technical Reports Server (NTRS)

Alloys based on FeAl, NiAl, and Ni3Al have been processed by extrusion of powders over a range of compositions, powder characteristics, and extrusion parameters. It is found that extrusion leads to dynamic recrystallization and that the grain size of the extrusions depends on the powder size, extrusion temperature, and extrusion ratio. Prior particle boundary oxides play an important role in controlling the grain size and uniformity by acting as obstacles to grain growth. Hot isostatic pressing and vacuum hot pressing can be used for powder densification, but prior particle oxides are not effectively broken up due to insufficient shearing deformation.

Vedula, K.; Stephens, J. R.

1987-01-01

404

Study of de-watering from the gelatinous precipitate formed during co-precipitation of Nd-YAG powder  

SciTech Connect

Neodymium doped Yttrium Aluminium Garnet (Nd:YAG) ceramics have been synthesised using coprecipitation technique and high temperature vacuum sintering. Gelatinous like precipitates were obtained when precursors of Nd, Al and Yb-nitrate solutions are co-precipitated using ammonia co-precipitant. De-watering from the gelatinous like precipitates is a big challenge and it possesses difficulty in filtration. Evaporation of water by heating resulted in strong agglomerated powder. Different agents were used to ease the filtration process, which is correlated with the phase in the calcined powder.

Karmakar, Sanjib; Sharma, Rachna; Pathak, S. K.; Gupta, S. M.; Gupta, P. K. [Laser Materials Development and Devices Division Raja Ramanna Centre for Advanced Technology, Indore-452013 (India)

2013-02-05

405

Particle-size reduction of Si3N4 powder with Si3N4 milling hardware  

NASA Technical Reports Server (NTRS)

The grinding of Si3N4 powder using reaction bonded Si3N4 attrition, vibratory, and ball mills with Si3N4 media was examined. The rate of particle size reduction and the change in the chemical composition of the powder were determined in order to compare the grinding efficiency and the increase in impurity content resulting from mill and media wear for each technique. Attrition and vibratory milling exhibited rates of specific surface area increase that were approximately eight times that observed in ball milling. Vibratory milling introduced the greatest impurity pickup.

Herbell, T. P.; Freedman, M. R.; Kiser, J. D.

1986-01-01

406

A sample-saving method for heat capacity measurements on powders using relaxation calorimetry  

PubMed Central

An experimental method is described for determining the low-temperature heat capacity (Cp) of mg-sized powder samples using the Quantum Design 揚hysical Properties Measurement System (PPMS). The powder is contained in an Al pan as an ?1爉m thick compressed layer. The sample is not mixed with Apiezon N grease, as compared to other methods. Thus, it is not contaminated and can be used for further study. This is necessary for samples that are only available in tiny amounts. To demonstrate the method various samples, all insulating in nature, were studied including benzoic acid, sapphire and different silicate minerals. The measurements show that the method has an accuracy in Cp to better than 1% at T above 3050燢 and 񶟓% up to 10% below. The experimental procedure is based on three independent PPMS and three independent differential scanning calorimetry (DSC) measurements. The DSC Cp data are used to slightly adjust the PPMS Cp data by a factor CpDSC/CpPPMSat298K. This is done because heat capacities measured with a DSC device are more accurate around ambient T (?0.6%) than PPMS values and is possible because the deviation of PPMS heat capacities from reference values is nearly constant between about 50燢 and 300燢. The resulting standard entropies agree with published reference values within 0.21% for the silicates, by 0.34% for corundum, and by 0.9% for powdered benzoic acid. The method thus allows entropy determinations on powders with an accuracy of better than 1%. The advantage of our method compared to other experimental techniques is that the sample powder is not contaminated with grease and that heat capacity values show less scatter at high temperatures. PMID:21886915

Dachs, Edgar; Benisek, Artur

2011-01-01

407

Injectable Calcium Phosphate Cement: Effects of Powder-to-Liquid Ratio and Needle Size  

PubMed Central

Calcium phosphate cement (CPC) sets in situ and forms apatite with excellent osteoconductivity and bone-replacement capability. The objectives of this study were to formulate an injectable tetracalcium phosphate-dicalcium phosphate cement (CPCD), and investigate the powder/liquid ratio and needle-size effects. The injection force (mean SD; n = 4) to extrude the paste increased from (8 2) N using a 10-gauge needle to (144 17) N using a 21-gauge needle (p < 0.05). With the 10-gauge needle, the mass percentage of extruded paste was (95 4)% at a powder/liquid ratio of 3; it decreased to (70 12)% at powder/liquid = 3.5 (p < 0.05). A relationship was established between injection force, F, and needle lumen cross-sectional area, A: F = 5.0 + 38.7/A0.8. Flexural strength, S, (mean SD; n = 5) increased from (5.3 0.8) MPa at powder/liquid = 2 to (11.0 0.8) MPa at powder/liquid = 3.5 (p < 0.05). Pore volume fraction, P, ranged from 62.4% to 47.9%. A relationship was established: S = 47.7 (1 - P)2.3. The strength of the injectable CPCD matched/exceeded the reported strengths of sintered porous hydroxyapatite implants that required machining. The novel injectable CPCD with a relatively high strength may be useful in filling defects with limited accessibility such as periodontal repair and tooth root-canal fillings, and in minimally-invasive techniques such as percutaneous vertebroplasty to fill the lesions and to strengthen the osteoporotic bone. PMID:17635038

Burguera, Elena F.; Sun, Limin

2009-01-01

408

Characterization of uniaxial compaction in spray dried ceramic powders  

NASA Astrophysics Data System (ADS)

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

Carneim, Robert David

409

Direct analysis of herbal powders by pipette-tip electrospray ionization mass spectrometry.  

PubMed

Conventional electrospray ionization mass spectrometry (ESI-MS) is widely used for analysis of solution samples. The development of solid-substrate ESI-MS allows direct ionization analysis of bulky solid samples. In this study, we developed pipette-tip ESI-MS, a technique that combines pipette tips with syringe and syringe pump, for direct analysis of herbal powders, another common form of samples. We demonstrated that various herbal powder samples, including herbal medicines and food samples, could be readily online extracted and analyzed using this technique. Various powder samples, such as Rhizoma coptidis, lotus plumule, great burdock achene, black pepper, Panax ginseng, roasted coffee beans, Fructus Schisandrae Chinensis and Fructus Schisandrae Sphenantherae, were analyzed using pipette-tip ESI-MS and quality mass spectra with stable and durable signals could be obtained. Both positive and negative ion modes were attempted and various compounds including amino acids, oligosaccharides, glycosides, alkaloids, organic acids, ginosensides, flavonoids and lignans could be detected. Principal component analysis (PCA) based on the acquired mass spectra allowed rapid differentiation of closely related herbal species. PMID:24418140

Wang, Haixing; So, Pui-Kin; Yao, Zhong-Ping

2014-01-27

410

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

NASA Astrophysics Data System (ADS)

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

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

411

Minimum ignition energy of nano and micro Ti powder in the presence of inert nano TiO? powder.  

PubMed

The inerting effect of nano-sized TiO2 powder on ignition sensitivity of nano and micro Ti powders was investigated with a Mike 3 apparatus. "A little is not good enough" is also suitable for micro Ti powders mixed with nano-sized solid inertants. MIE of the mixtures did not significantly increase until the TiO2 percentage exceeded 50%. Nano-sized TiO2 powders were ineffective as an inertant when mixed with nano Ti powders, especially at higher dust loadings. Even with 90% nano TiO2 powder, mixtures still showed high ignition sensitivity because the statistic energy was as low as 2.1 mJ. Layer fires induced by ignited but unburned metal particles may occur for micro Ti powders mixed with nano TiO2 powders following a low level dust explosion. Such layer fires could lead to a violent dust explosion after a second dispersion. Thus, additional attention is needed to prevent metallic layer fires even where electric spark potential is low. In the case of nano Ti powder, no layer fires were observed because of less flammable material involved in the mixtures investigated, and faster flame propagation in nanoparticle clouds. PMID:24797905

Chunmiao, Yuan; Amyotte, Paul R; Hossain, Md Nur; Li, Chang

2014-06-15

412

Nutritional composition of ginger powder prepared using various drying methods.  

PubMed

A study was undertaken to prepare ginger powder using various drying methods and their nutritional evaluation was carried out. Ginger (Zingiber officinale) was dried using shade, solar, oven and microwave drying methods. All the samples were ground in grinder to make fine powder. Sensory analysis indicated that acceptability of all types of ginger powders were in the range of 'liked very much' to 'liked moderately' by the panelists. The mean score obtained for colour was higher in shade dried ginger powder i.e., 8.20 as compared to oven dried (7.60), solar dried (7.70) and microwave dried ginger powder (7.80). Moisture content ranged from 3.55% in solar dried ginger powder to 3.78% in shade dried ginger powder. Slightly higher moisture content was found in shade dried ginger powder. Protein, crude fiber, fat and ash contents ranged from 5.02 to 5.82, 4.97 to 5.61, 0.76 to 0.90 and 3.38 to 3.66%, respectively. ?-carotene and ascorbic acid content was found maximum in shade dried ginger powder i.e., 0.81爉g/100爂 and 3.83爉g/100爂, respectively. Polyphenol content was almost similar in all the samples whereas calcium was slightly higher in the shade dried ginger powder i.e., 69.21爉g/100爂. Results have shown that ginger powder prepared from various drying methods had good sensory and nutritional profile. PMID:25190894

Sangwan, A; Kawatra, A; Sehgal, S

2014-09-01

413

Identification of low amount of irradiated spices (red pepper, garlic, ginger powder) with luminescence analysis  

NASA Astrophysics Data System (ADS)

For the identification of irradiated food, current analysis methods have limitations regarding presence and stability of radiation-induced markers. In this study, different spice blends with small quantity of different irradiated (0, 1 and 10 kGy) spice powders, such as red pepper, garlic or ginger, were investigated using PSL and TL techniques. In PSL-based screening analysis, the spice blends containing 10% of irradiated materials (1 or 10 kGy) were determined as intermediate or positive. In TL results, the blends containing 1% of 1 or 10 kGy-irradiated spices showed the typical TL glow curves that could be interpreted as positive. The blends with irradiated garlic powder provided more good results where identification was possible at 0.5% mixing of irradiated sample. However, the TL ratios of all spice blends were <0.1 and only TL glow curve shape and intensity may be used to discriminate the samples having irradiated component.

Kim, Byeong-Keun; Akram, Kashif; Kim, Cheong-Tae; Kang, Na-Roo; Lee, Jin-Won; Ryang, Jun-Hwan; Kwon, Joong-Ho

2012-08-01

414

Microstructures and properties of nanocomposites obtained through SPTS consolidation of powders  

SciTech Connect

The microstructures and properties of copper- and aluminum-based nanocomposites processed through severe plastic torsional straining (SPTS) consolidation of metallic micrometer powders and ceramic nanopowders were investigated by transmission electron microscopy (TEM), X-ray diffraction (XRD), microhardness and electrical resistivity measurements, and mechanical tests. It was shown that the SPTS consolidation of powders is an effective technique for fabricating metal-ceramic nanocomposites with a high density, ultrafine grain size, and high strength. Copper samples processed under a high pressure of 6 GPa exhibited high failure strength and strain as well as unusual strain hardening. Superplastic-like behavior was found in Al-Al{sub 2}O{sub 3} nanocomposite samples.

Alexandrov, I.V.; Islamgaliev, R.K.; Valiev, R.Z. [Ufa State Aviation Technical Univ. (Russian Federation). Inst. of Physics of Advanced Materials; Zhu, Y.T.; Lowe, T.C. [Los Alamos National Lab., NM (United States). Materials Science and Technology Div.

1998-09-01

415

Hydration mechanisms of ternary Portland cements containing limestone powder and fly ash  

SciTech Connect

The effect of minor additions of limestone powder on the properties of fly ash blended cements was investigated in this study using isothermal calorimetry, thermogravimetry (TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM) techniques, and pore solution analysis. The presence of limestone powder led to the formation of hemi- and monocarbonate and to a stabilisation of ettringite compared to the limestone-free cements, where a part of the ettringite converted to monosulphate. Thus, the presence of 5% of limestone led to an increase of the volume of the hydrates, as visible in the increase in chemical shrinkage, and an increase in compressive strength. This effect was amplified for the fly ash/limestone blended cements due to the additional alumina provided by the fly ash reaction.

De Weerdt, K., E-mail: klaartje.de.weerdt@sintef.n [SINTEF Building and Infrastructure, 7465 Trondheim (Norway); Haha, M. Ben; Le Saout, G. [EMPA, Swiss Federal Laboratories for Material Science and Technology, Laboratory for Concrete and Construction chemistry, 8600 Duebendorf (Switzerland); Kjellsen, K.O. [NTNU, Department of Structural Engineering, 7491 Trondheim (Norway); Norcem AS HeidelbergCement, Setreveien 2, 3991 Brevik (Norway); Justnes, H. [SINTEF Building and Infrastructure, 7465 Trondheim (Norway); Lothenbach, B. [EMPA, Swiss Federal Laboratories for Material Science and Technology, Laboratory for Concrete and Construction chemistry, 8600 Duebendorf (Switzerland)

2011-03-15

416

Full sintering of powdered-metal bodies in a microwave field  

NASA Astrophysics Data System (ADS)

The use of microwaves to process absorbing materials was studied intensively in the 1970s and 1980s, and has now been applied to a wide variety of materials. Initially, success in microwave heating and sintering was confined mainly to oxide and some non-oxide ceramics; but recently the technique has been extended to carbide semimetals used in cutting tools. Here we describe the microwave sintering of powdered metals to full density. We are able to sinter a wide range of standard powdered metals from commercial sources using a 2.45-GHz microwave field, yielding dense products with better mechanical properties than those obtained by conventional heating. These findings are surprising in view of the reflectivity of bulk metals at microwave frequencies. The ability to sinter metals with microwaves should assist in the preparation of high-performance metal parts needed in many industries, for example, in the automotive industry.

Roy, Rustum; Agrawal, Dinesh; Cheng, Jiping; Gedevanishvili, Shalva

1999-06-01

417

Innovative Powder Processing of Oxide Dispersion Strengthened ODS Ferritic Stainless Steels  

SciTech Connect

An innovative gas atomization reaction synthesis technique was employed as a viable method to dramatically lower the processing cost for precursor oxide dispersion forming ferritic stainless steel powders (i.e., Fe-Cr-(Hf,Ti)-Y). During this rapid solidification process the atomized powders were enveloped by a nano-metric Cr-enriched metastable oxide film. Elevated temperature heat treatment was used to dissociate this metastable oxide phase through oxygen exchange reactions with Y-(Hf,Ti) enriched intermetallic compound precipitates. These solid state reactions resulted in the formation of highly stable nano-metric mixed oxide dispersoids (i.e., Y-Ti-O or Y-Hf-O) throughout the alloy microstructure. Subsequent high temperature (1200 C) heat treatments were used to elucidate the thermal stability of each nano-metric oxide dispersoid phase. Transmission electron microscopy coupled with X-ray diffraction was used to evaluate phase evolution within the alloy microstructure.

Rieken, Joel; Anderson, Iver; Kramer, Matthew

2011-04-01

418

A study of shock-induced reactivity in a porous pyrotechnic powder mixture  

NASA Astrophysics Data System (ADS)

Shock and reactive properties of a pressed pyrotechnic powder mixture were examined using gun-launched planar impact techniques. The pyrotechnic powder consisted of a mixture of potassium perchlorate, magnesium-aluminum alloy, and inert binder pressed to approximately 84% theoretical maximum density (TMD). Polyvinylidene fluoride (PVDF) piezoelectric polymer film shock-pressure gages were used to track the progress of the shock wave through the mixture and establish the shock Hugoniot and pressure-time trends. A comparison of experimental pressure-time trends with those obtained using a one-dimensional hydrocode shows good agreement for input pressures below 2 GPa, but increasing differences for pressures above 2.6 GPa. These differences, in the form of rising pressure levels in the region immediately behind the shock front for the experimental data, are tentatively attributed to shock-induced chemical reaction.

Lindfors, A. J.; Finnegan, S. A.; Boteler, J. M.

1996-05-01

419

Genuair() in chronic obstructive pulmonary disease: a novel, user-friendly, multidose, dry-powder inhaler.  

PubMed

Inhaled corticosteroids and bronchodilators, which are pivotal to the management of respiratory diseases, are delivered by numerous devices, including pressurized metered-dose inhalers and dry-powder inhalers. However, patient adherence to these medications is suboptimal and incorrect inhaler technique is endemic, meaning that insufficient drug quantities are frequently delivered to the lungs. Genuair() (Almirall SA, Spain) is a novel, breath-actuated, multidose dry-powder inhaler designed to achieve reliable and effective delivery of inhaled medicines - including aclidinium bromide - to patients with chronic obstructive pulmonary disease. In addition to describing Genuair's design, which incorporates multiple feedback mechanisms in order to confirm effective medication uptake, this article discusses the performance characteristics of the inhaler, its efficiency in terms of drug deposition and the results of recent patient preference and satisfaction studies. PMID:25287386

der Palen, Job van

2014-07-01

420

Spacing-dependent dipolar interactions in dendronized magnetic iron oxide nanoparticle 2D arrays and powders.  

PubMed

Self-assembly of nanoparticles (NPs) into tailored structures is a promising strategy for the production and design of materials with new functions. In this work, 2D arrays of iron oxide NPs with interparticle distances tuned by grafting fatty acids and dendritic molecules at the NPs surface have been obtained over large areas with high density using the Langmuir-Blodgett technique. The anchoring agent of molecules and the Janus structure of NPs are shown to be key parameters driving the deposition. Finally the influence of interparticle distance on the collective magnetic properties in powders and in monolayers is clearly demonstrated by DC and AC SQUID measurements. The blocking temperature T(B) increases as the interparticle distance decreases, which is consistent with the fact that dipolar interactions are responsible for this increase. Dipolar interactions are found to be stronger for particles assembled in thin films compared to powdered samples and may be described by using the Vogel Fulcher model. PMID:23306456

Fleutot, Solenne; Nealon, Gareth L; Pauly, Matthias; Pichon, Benoit P; Leuvrey, C閐ric; Drillon, Marc; Gallani, Jean-Louis; Guillon, Daniel; Donnio, Bertrand; Begin-Colin, Sylvie

2013-02-21

421

Powder characteristics and microstructure of uranium dioxide and uranium dioxide-gadolinium oxide fuel  

NASA Astrophysics Data System (ADS)

Three different fuels UO 2-only, UO 2-Gd 2O 3(5%), and UO 2-Gd 2O 3(10%) were produced by sol-gel technique. Their powder characteristics such as flowability, BET surface area, average pore diameter, and cumulative pore volume were determined. The pore size distributions of powders, green pellets, and sintered fuels were determined by using a mercury porosimeter. The theoretical densities of sintered fuels were found to be 98.01, 95.3, and 95.9%, respectively. Their ruggedness fractal dimensions were 1.111, 1.044, and 1.042, while the fractal dimensions associated with the size distribution of grains were 1.44, 1.58, and 1.60, respectively.

G黱d鼁, G黱g鰎; Uslu, ?brahim

1996-07-01

422

Rapid detection of whey in milk powder samples by spectrophotometric and multivariate calibration.  

PubMed

A rapid method for the detection and quantification of the adulteration of milk powder by the addition of whey was assessed by measuring glycomacropeptide protein using mid-infrared spectroscopy (MIR). Fluid milk samples were dried and then spiked with different concentrations of GMP and whey. Calibration models were developed using multivariate techniques, from spectral data. For the principal component analysis and discriminant analysis, excellent percentages of correct classification were achieved in accordance with the increase in the proportion of whey samples. For partial least squares regression analysis, the correlation coefficient (r) and root mean square error of prediction (RMSEP) in the best model were 0.9885 and 1.17, respectively. The rapid analysis, low cost monitoring and high throughput number of samples tested per unit time indicate that MIR spectroscopy may hold potential as a rapid and reliable method for detecting milk powder frauds using cheese whey. PMID:25529644

de Carvalho, Bruna Mara Aparecida; de Carvalho, Lorendane Millena; Dos Reis Coimbra, Jane S閘ia; Minim, Luis Ant鬾io; de Souza Barcellos, Edilton; da Silva J鷑ior, Willer Ferreira; Detmann, Edenio; de Carvalho, Gleidson Giordano Pinto

2015-05-01

423

Proton glass freezing in hydrated lysozyme powders.  

PubMed

At room temperature, the dielectric relaxation of hydrated powder of the protein lysozyme is known to be due to protons migrating between ionized side chains. A recent study of this relaxation at lower temperatures suggested a behavior typical of proton glasses. An analysis of the complex dielectric susceptibility by a temperature-frequency plot presented here has revealed that ergodicity is broken due to the divergence of the longest relaxation time at 266 K, indicating specifically that this hydrated protein is a proton glass. A change in the temperature behavior of the static dielectric constant and the average relaxation frequency at 273 K indicates a further transition occurring at this temperature, whose nature remains to be investigated. PMID:11970721

Levstik, A; Filipic, C; Kutnjak, Z; Careri, G; Consolini, G; Bruni, F

1999-12-01

424

Neutron powder diffraction study of perdeuterodimethyl sulfone.  

PubMed

The crystal structure of perdeuterodimethyl sulfone, (CD(3))(2)SO(2) or C(2)D(6)O(2)S, has been refined at 4.5 K against high-resolution neutron powder diffraction data. The structure determined previously by Sands [Z. Kristallogr. (1963), 119, 245-251] at ambient temperature is shown to remain down to liquid helium temperature, and at 4.5 K the S-C and S-O bond distances are 1.441 (2) and 1.760 (2) A, respectively. The molecules are distorted tetrahedra with C(2v) point symmetry (crystallographic symmetry m2m for S and m for C, O and one D atom) and are linked through a network of weak hydrogen bonds in the C-centred orthorhombic structure. PMID:17478915

Ibberson, R M

2007-05-01

425

Small-angle X-ray scattering study of the structure of powder fullerene C60 and fullerene soot  

NASA Astrophysics Data System (ADS)

Powder samples of fullerene C60 and fullerene soot have been studied by the small-angle X-ray scattering method. The radii of gyration of scattering elements have been determined by constructing small-angle diffraction patterns in Guinier coordinates. The data obtained agree well with the results of wide-angle X-ray scattering study, the available data on the structure of the powder fullerene C60 prepared by the Huffman-Kr鋞schmer technique, and the structure of the C60 molecules. Conglomerates of two C60 molecules, along with crystallites 20 nm in size that are distributed in an amorphous matrix, are present in fullerene powders. Fullerene soot contains C60 crystallites 20-25 nm in size and graphite crystallites 2-3 nm in size that are distributed in an amorphous matrix.

Ginzburg, B. M.; Tu?chiev, Sh.; Tabarov, S. Kh.; Shepelevski?, A. A.

2007-03-01

426

Rapid flow cytometry analysis of antimicrobial properties of nettle powder and cranberry powder  

NASA Astrophysics Data System (ADS)

Both nettle (Urtica dioica) and cranberry (Vaccinium oxycoccus) are widely known to have good influence on health. The aim of this study was to investigate antimicrobial properties of nettle powder and cranberry powder against Escherichia coli (E. coli) and monitor the growth of the bacteria by a rapid flow cytometry (FCM) method. For FCM measurements samples were stained with fluorescent dyes. The inhibitory effects of plant material on growth of E. coli were estimated by comparing the results of control sample (E. coli) to E. coli samples with plant material. FCM offers both a brilliant tool to investigate the kinetics of the growth of bacterium, since subsamples can be taken from the same liquid medium during the growing period and with fluorescent dyes a rapid method to investigate viability of the bacterium.

Hattuniemi, Maarit; Korhonen, Johanna; Jaakkola, Mari; R鋞y, Jarkko; Virtanen, Vesa

2010-11-01

427

Interior view of main corridor, with door to powder room ...  

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

Interior view of main corridor, with door to powder room (labeled "Magazine") in foreground, plotting room with barred windows and double doors in middle, and second powder room door in background - U.S. Naval Base, Pearl Harbor, Battery Adair, Princeton Place, Pearl City, Honolulu County, HI

428

Immunodetection of added glycomacropeptide in milk formulas and milk powders.  

PubMed

The present study aimed the detection of fraudulent manipulation of milk powder with a low cost component--whey powder, by applying the immunochromatographic assay to identify glycomacropeptide. Five commercial milk powder samples of various brands from the national market were analyzed: lactose enriched milk powder type 26, two whole milk powders, vitamin enriched milk powder and full cream milk powder. Our results showed additional whey (1-2%) in 60% of the selected samples after casein removal by precipitation with 20% trichloracetic acid. Another investigated sample--the enriched UHT milk for children aged 4-12 years--proved addition of whey. Other two commercial toddler formula milk powder samples of different brands were used for comparison for the presence of glycomacropeptide. The first sample which was regularly labeled as containing whey protein concentrate was found positive for glycomacropeptide in accordance with the label information, while the second one not containing whey proteins as specified by the product label, was found negative for glycomacropeptide, these two samples being in accordance with the actual legislation. PMID:21717808

Oancea, Simona; Stoia, Mihaela

2011-01-01

429

81. BUILDING NO. 561, CANNON POWDER BLENDER, LOOKING NORTHWEST, BUILDING ...  

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

81. BUILDING NO. 561, CANNON POWDER BLENDER, LOOKING NORTHWEST, BUILDING NO. 561-A, PROPELLANT PLANT (FIREPROOF SHELTER), IN FOREGROUND, BUILDING NO. 561-D IN EXTREME FOREGROUND. - Picatinny Arsenal, 500 Area, Powder Factory & Power House, State Route 15 near I-80, Dover, Morris County, NJ

430

Properties of soluble protein powders from Alaska pollock (Theragra chalcogramma)  

Technology Transfer Automated Retrieval System (TEKTRAN)

Soluble protein powders were produced from pollock by-products and evaluated for their functional, nutritional and rheological properties. Soluble protein powders were made from pollock viscera (PVSP), viscer without liver (PVWLSP), heads (PHSP), frames (PFSP), trimmings (PTSP), and liver (PLSP) and...

431

21 CFR 520.905d - Fenbendazole powder.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false Fenbendazole powder. 520.905d Section 520...FORM NEW ANIMAL DRUGS 520.905d Fenbendazole powder. (a) Specifications...contains 2.27 grams (4 percent) of fenbendazole plus other inert ingredients....

2010-04-01

432

21 CFR 520.1696c - Penicillin V powder.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 2013-04-01 false Penicillin V powder. 520.1696c Section 520...FORM NEW ANIMAL DRUGS 520.1696c Penicillin V powder. (a) Specifications...contains 25 milligrams (40,000 units) of penicillin V. (b) Sponsor. See No....

2013-04-01

433

21 CFR 520.1696c - Penicillin V powder.  

...2014-04-01 2014-04-01 false Penicillin V powder. 520.1696c Section 520...FORM NEW ANIMAL DRUGS 520.1696c Penicillin V powder. (a) Specifications...contains 25 milligrams (40,000 units) of penicillin V. (b) Sponsor. See No....

2014-04-01

434

Measles vaccination of macaques by dry powder inhalation  

Microsoft Academic Search

Measles vaccination via the aerosol route has proven effective under field conditions, using vaccine reconstituted prior to nebulization. Inhalation of a dry powder aerosol vaccine would have additional benefits, including easier logistics of administration, reduced cold chain dependence and the potential of single dose administration. We have evaluated two candidate dry powder measles vaccine formulations in macaques. Specific immune responses

Rik L. de Swart; Cynthia LiCalsi; Alan V. Quirk; Geert van Amerongen; Vladislav Nodelman; Robert Alcock; Selma Y黭sel; Gary H. Ward; John G. Hardy; Helma Vos; Clyde L. Witham; Christopher I. Grainger; Thijs Kuiken; Bernard J. Greenspan; Trevor G. Gard; Albert D. M. E. Osterhaus

2007-01-01

435

21 CFR 520.154c - Bacitracin zinc soluble powder.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 2013-04-01 false Bacitracin zinc soluble powder. 520.154c Section...ANIMAL DRUGS 520.154c Bacitracin zinc soluble powder. (a) Specifications...perfringens susceptible to bacitracin zinc. (B) Limitations . Prepare a...

2013-04-01

436

21 CFR 520.154c - Bacitracin zinc soluble powder.  

...2014-04-01 2014-04-01 false Bacitracin zinc soluble powder. 520.154c Section...ANIMAL DRUGS 520.154c Bacitracin zinc soluble powder. (a) Specifications...perfringens susceptible to bacitracin zinc. (B) Limitations. Prepare a...

2014-04-01

437

21 CFR 520.154c - Bacitracin zinc soluble powder.  

Code of Federal Regulations, 2012 CFR

...2012-04-01 2012-04-01 false Bacitracin zinc soluble powder. 520.154c Section...ANIMAL DRUGS 520.154c Bacitracin zinc soluble powder. (a) Specifications...perfringens susceptible to bacitracin zinc. (B) Limitations . Prepare a...

2012-04-01

438

Novel dry powder inhalation system based on dispersion of lyophilisates  

Microsoft Academic Search

Dry powder inhalers and dry powder formulations experience a growing interest and are the subject of continuous further development. In this study the objective was to evaluate the possible aerosolization of lyophilisates by an air impact and to prove this new concept of creating individual inhalable particles from a coherent bulk at the time of inhalation. Therefore an output test

Sarah Claus; Tilo Schoenbrodt; Claudius Weiler; Wolfgang Friess

2011-01-01

439

Powdered hide model for vegetable tanning II. hydrolyzable tannin  

Technology Transfer Automated Retrieval System (TEKTRAN)

Vegetable tannages employ both condensed and hydrolyzable tannins. As part of our exploration of tanning mechanisms, we reported last year on interactions of the condensed tannin, quebracho, with powdered hide. In this study, the interactions of chestnut extract, a hydrolyzable tannin, with powdere...

440

84. BUILDING NO. 561, LOOKING SOUTHEAST AT CANNON POWDER BLENDER ...  

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

84. BUILDING NO. 561, LOOKING SOUTHEAST AT CANNON POWDER BLENDER FROM ACROSS PICATINNY LAKE. LOUVERED WALL FACING LAKE WAS DESIGNED TO RELIEVE BLASTS AND DIRECT THEM TOWARD LAKE IF THEY OCCURRED. - Picatinny Arsenal, 500 Area, Powder Factory & Power House, State Route 15 near I-80, Dover, Morris County, NJ

441

Mathematical modeling of powder-snow avalanche flows  

E-print Network

Mathematical modeling of powder-snow avalanche flows Denys Dutykh a, aLAMA, UMR 5127 CNRS麓e de Savoie, 73376 Le Bourget-du-Lac Cedex, France Abstract Powder-snow avalanches are violent natural. In this study we present a novel model for the simulation of avalanches in the aerosol regime. The second scope

442

Synthesis and chemical reactivity of polyol prepared monodisperse nickel powders  

Microsoft Academic Search

Monodisperse 1350 Ni powders are prepared according to the polyol process using polyvinylpyrrolidone (PVP) as a protective agent. Smaller size monodisperse Ni powders (300 ) have presently been made from Ni(OH)2 in ethylene glycol (EG) and PVP using Pd or Pt as nucleating agents. Thermogravimetric Analysis (TGA) and Temperature Programmed Desorption (TPD) measurements in air showed that ethylene glycol

M. S. Hegde; D. Larcher; L. Dupont; B. Beaudoin; K. Tekaia-Elhsissen; J.-M. Tarascon

1996-01-01

443

Thermal processes of a powder particle in coaxial laser cladding  

Microsoft Academic Search

This paper presents a numerical analysis of the heating, melting and evaporation processes of a single spherical powder particle when irradiated by a CO2 laser beam in coaxial laser cladding. The power particle has a size ranging from 20 to 200?m and the intensity of the laser has been varied from 500 to 3000W. The laser energy, initial powder velocity

Chang-Yi Liu; Jehnming Lin

2003-01-01

444

Powdered versus granular carbon for oil refinery wastewater treatment  

Microsoft Academic Search

Pilot studies were conducted on two activated carbon-based systems for meeting the effluent quality requirements of an oil refinery. Upgrading of activated sludge by addition of powdered activated carbon directly into aeration tank mixed liquor and tertiary treatment of activated sludge effluent by granular carbon adsorption were studied. Powdered carbon enhancement was found to be more cost-effective than granular carbon

C. G. Grieves; L. W. Crame; D. G. Venardos; W. Ying

1980-01-01

445

Plastic deformation and yield criterion for compressible sintered powder materials  

Microsoft Academic Search

This paper analyses the basic aspects of plastic deformation behaviours of compressible sintered powder materials, such as plastic volume change, mass constancy, small Poisson's ratio and the effect of hydrostatic pressure on yield. Based on the uniaxial compression tests using sintered powder copper as a model material, the true stress杝train equation, a generalized yield criterion and some plastic constitutive equations

Lin Hua; Xunpeng Qin; Huajie Mao; Yumin Zhao

2006-01-01

446

Powder diffraction from a combinatorial and analytic viewpoint A. Iosevich  

E-print Network

Powder diffraction from a combinatorial and analytic viewpoint A. Iosevich and M. Rudnev September 14, 2005 Abstract The mathematical theory of the powder diffraction intensity function is presented method of processing the diffraction data, this paper stresses the importance of the moments

Rudnev, Misha

447

COAL QUALITY AND GEOCHEMISTRY, POWDER RIVER BASIN, WYOMING AND MONTANA  

E-print Network

distribution in the Wyodak- Anderson coal zone in the Powder River Basin. PQ-3. Ash yield in the WyodakChapter PQ COAL QUALITY AND GEOCHEMISTRY, POWDER RIVER BASIN, WYOMING AND MONTANA By G.D. Stricker Tertiary coal beds and zones in the Northern RockyMountains and Great Plains region, U.S. Geological Survey

448

Dissolution and reconstitution of casein micelle containing dairy powders by high shear using ultrasonic and physical methods.  

PubMed

The effect of shear on the solubilization of a range of dairy powders was investigated. The rate of solubilization of low solubility milk protein concentrate and micellar casein powders was examined during ultrasonication, high pressure homogenization and high-shear rotor-stator mixing and compared to low-shear overhead stirring. The high shear techniques were able to greatly accelerate the solubilization of these powders by physically breaking apart the powder agglomerates and accelerating the release of individual casein micelles into solution. This was achieved without affecting the structure of the solubilized proteins. The effect of high shear on the re-establishment of the mineral balance between the casein micelles and the serum was examined by monitoring the pH of the reconstituted skim milk powder after prior exposure to ultrasonication. Only minor differences in the re-equilibration of the pH were observed after sonication for up to 3 min, suggesting that the localized high shear forces exerted by sonication did not significantly affect the mass transfer of minerals from within the casein micelles. PMID:24798226

Chandrapala, Jayani; Martin, Gregory J O; Kentish, Sandra E; Ashokkumar, Muthupandian

2014-09-01

449

Effect of dispersant on preparation of barium-strontium titanate powders through oxalate co-precipitation method  

SciTech Connect

The quantitative precipitation of barium-strontium titanyl oxalate: (Ba{sub 0.6}Sr{sub 0.4}TiO(C{sub 2}O{sub 4}){sub 2}.4H{sub 2}O, BSTO) precursor powders were successfully prepared through oxalate co-precipitation method. The pyrolysis of BSTO at 800 deg. C/4 h produced the barium-strontium titanate (Ba{sub 0.6}Sr{sub 0.4}TiO{sub 3}, BST) powders. Two kinds of dispersants namely ammonium salt of poly mathacrylic acid (PMAA-NH{sub 4}) and polyethylene glycol (PEG) were added respectively during the co-precipitation procedure. The powders were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), etc. Experimental results show that the addition of the dispersants reduced the productive rate of BST powders. The BSTO and BST powders obtained by aforementioned technique without dispersants were homogeneous with quasi-orbicular morphology. The particles grew into spindle shape with the effect of PEG. The morphology homogeneity was broke with small grains as well as large agglomerated particles concurrent when PMAA-NH{sub 4} was added. The mechanism of the effect of the two dispersants was investigated in detail.

Li Mingli [School of Materials Science and Engineering, Key Laboratory for Advanced Ceramics and Machining Technology of Ministry of Education, Tianjin University, Weijin Road 92, Tianjin 300072 (China)], E-mail: lml@tju.edu.cn; Xu Mingxia [School of Materials Science and Engineering, Key Laboratory for Advanced Ceramics and Machining Technology of Ministry of Education, Tianjin University, Weijin Road 92, Tianjin 300072 (China)

2009-04-02

450

Preparation of ultrafine boride powders by metallothermic reduction method  

NASA Astrophysics Data System (ADS)

Ultrafine TiB2, ZrB2, and ReB2 powders were prepared by the metallothermic reduction method using Mg. Obtained TiB2, ZrB2, and ReB2 powders were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, dynamic light scattering, and scratch test. The morphology of the powders was a laminar hexagonal single crystal. The mean particle sizes of TiB2 and ZrB2 increased with increasing reaction temperature, and that of ReB2 was 0.11 ?m at 1093 K. The obtained ReB2 powder can scratch the surface of polycrystalline synthetic diamonds (HK = 7000 kg/mm2). The obtained powders will be useful for developing of new superhard alloys and pigments.

Nishiyama, Katsuhiro; Nakamur, Takanobu; Utsumi, Shigenori; Sakai, Hideki; Abe, Masahiko

2009-06-01

451

Production of ceramic powders from laser-driven reactions  

NASA Astrophysics Data System (ADS)

Laser photo induced reactions from gaseous precursors have been applied to the synthesis of nanosized silicon carbonitrides and (gamma) -alumina based powders. Silicon carbonitrides with different structures and chemical compositions have been produced by changing the reactant gases or their relative concentrations. The structural and chemical evolution have been studied by thermal treatments in Ar and N2 atmosphere. The results confirm the applicability of this powder for industrial applications. Concerning the (gamma) -alumina powder, changes in the reactants concentration ratio have shown to influence both the process yield and the composition of the outcoming powders. Nitrogen or carbon rich (gamma) - alumina powders (Al3O3N, Al2OC) have been synthesized. Some recent and encouraging results on the thermal properties of laser produced silicon carbide are also presented.

Borsella, E.; Botti, S.; Cesile, M. C.; Martelli, Stefano; Nesterenko, A.; Giorgi, Rossella; Turtu, S.; Alexandrescu, Rodica; Morjan, Ion G.

1995-03-01

452

A simple solution-polymerization route for oxide powder synthesis  

SciTech Connect

A simple solution polymerization route based on polyvinyl alcohol (PVA) as the organic carrier for the cations is used to process pure, mixed oxide powders. Simultaneous DTA/TGA analyses revealed that the organics are burnt out below 600{degrees}C. The new system produces X-ray amorphous, fine, white powders at temperatures as low as 650{degrees}C. The powders thus prepared have a 12 m{sup 2}/g as-calcined specific surface area. The successful use of a non-chelating polymer for the solution polymerization method indicated that cation chelation is not the only route for creating stable ceramic precursors. The process has a net yield of 1.8 for the weight ratio of the mixed oxide powder to the organics. The organic carrier has a significant influence on the morphology of the final ceramic powder.

Guelguen, M.A.; Kriven, W.M. [Univ. of Illinois, Urbana, IL (United States)

1996-06-01

453

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

Microsoft Academic Search

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

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

1999-01-01

454

Effect of powdered activated carbon on the biodegradation of benzene  

SciTech Connect

The objectives were to determine the effect of powdered activated carbon (PAC) on the biodegradation of benzene and to evaluate the sorptive characteristics of biomass for benzene. Measurements of oxygen uptake by microorganisms utilizing benzene as a sole source of carbon were made. Various concentrations of PAC were used and each test was conducted using a selected food to microorganism ratio (F/M), based on the theoretical oxygen demand (TOD) of the benzene substrate, the mixed liquor volatile suspended solids (MLVSS) concentration, and a detention time of one day. Completely mixed cultures of aerobic/facultative organisms, acclimated in a bench-scale unit, were injected into Warburg reaction flasks, containing the benzene substrate and PAC. Purge and trap analytical techniques were used to evaluate sorption of benzene onto the biomass. Inactivated microorganisms mixed with various concentrations of benzene provided the basis for the sorption evaluations. PAC provided an optimum benzene concentration for microbial oxidation to proceed, although the overall effect was small. The oxidation of benzene by acclimated organisms was upwards of 90 percent of the theoretical oxygen demand and sorption of benzene onto biomass appeared to follow Langmuir's model. 11 tables, 22 figures.

Allen, D.A.; Gloyna, E.F.

1980-12-01

455

Removal of surfactants by powdered activated carbon and microfiltration.  

PubMed

Direct and indirect releases of large quantities of surfactants to the environment may result in serious health and environmental problems. Therefore, surfactants should be removed from water before release to the environment or delivery for public use. Using powdered activated carbon (PAC) as adsorbent and separating particles with a membrane may be an effective technique to remove surfactants. In this study, the removal of surfactants by microfiltration and PAC was investigated and the influences of the operating parameters on the effectiveness on microfiltration were determined. An anionic (LABS) and a cationic surfactant (CTAB) were selected for the experiments. A series of batch experiments were performed to determine the sorption isotherms of surfactants to PAC. Then microfiltration experiments were carried out. The results showed that formation of secondary membrane on the surface and, within the pores of the membrane, increased the retention of surfactants significantly. Increase in transmembrane pressure and pore size of the membrane decreased the rejection rates, but increase in cross-flow velocity increased the rejection rate. Temperature had no apparent affect on the efficiency of surfactant removal. Presence of electrolyte had different effects on CTAB and LABS. The rejection rates of CTAB significantly increased when the concentration of NaCl increased; however, a slight decrease was observed in the rejection rate of LABS at the same conditions. PMID:15087193

Basar, Canan Akbil; Karagunduz, Ahmet; Cakici, Avni; Keskinler, Bulent

2004-04-01

456

Modulation techniques  

NASA Technical Reports Server (NTRS)

Bandwidth efficient digital modulation techniques, proposed for use on and/or applied to satellite channels, are reviewed. In a survey of recent works on digital modulation techniques, the performance of several schemes operating in various environments are compared. Topics covered include: (1) quadrature phase shift keying; (2) offset - QPSK and MSK; (3) combined modulation and coding; and (4) spectrally efficient modulation techniques.

Schilling, D. L.

1982-01-01

457

Comparison of adsorption performances of powdered activated sludge and powdered activated carbon for removal of turquoise blue dyestuff  

Microsoft Academic Search

Effective treatment of dyestuff containing wastewaters require advanced treatment technologies such as adsorption for the removal of dyestuffs. Powdered activated carbon (PAC) has been the most widely used adsorbent for the removal of dyestuffs from wastewaters. As an alternative to PAC, powdered activated sludge (PAS) was used as adsorbent for dyestuff removal from synthetic wastewater in this study. The colour

Fikret Kargi; Serpil Ozm?hc?

2005-01-01

458

A portable powder-liquid high corrosion-resistant reaction cell for in situ X-ray diffraction and absorption studies of heterogeneous powder-liquid reactions and phase transformations  

NASA Astrophysics Data System (ADS)

A portable powder-liquid high corrosion-resistant reaction cell has been designed to follow in situ reactions by X-ray powder diffraction and X-ray absorption spectroscopy techniques in transmission mode. The cell has been conceived to be mounted on the experimental stations for diffraction and absorption of the Spanish CRG SpLine-BM25 beamline at the ESRF. In the case of the diffraction technique, data can be collected with either a point detector or a two-dimensional CCD detector. Using the 2D-CCD camera, the cell can be used for time-resolved in situ studies of phase transitions and reactions. Powder reactants and/or products are kept at a fixed position in a vertical geometry in the X-ray pathway, which is minimized in order to reduce the X-ray absorption by the reaction bath. Sample is fixed by a porous membrane under forced liquid reflux circulation, assuring total powder-liquid contact, with an accurate temperature control in the range from 20 to 220癈.

Ferrer, P.; da Silva, I.; Heyman, C.; Rubio-Zuazo, J.; Castro, G. R.

2013-03-01

459

Investigation of Space Charge Trap Levels in Al2O3 Nano-Powder Doped Polyethylene by Photo-Stimulated Discharge Method  

NASA Astrophysics Data System (ADS)

The trap levels of Al2O3 nano-powder doped LDPE with different Al2O3 contents are investigated by PSD technique. The variation of trap depth in the doped LDPE can be qualitatively estimated by PSD spectra in continuous scanning method, and the distribution of trap levels in the samples can be quantitatively described in step scanning method. It is indicated that the trap levels of LDPE can be evidently deepened by Al2O3 nano-powder doping with the content more than 0.1 wt%. According to the relative reports on the effect of nano-powder doping to space charge injection, it is considered that the suppression of space charge is probably correlated to the deeper trap levels in Al2O3 nano-powder doped LDPE.

Zhu, Zhien; Zhang, Yewen; An, Zhenlian; Zheng, Feihu

2012-10-01

460

The use of gamma irradiation in preparation of polybutadiene rubber nanopowder; Its effect on particle size, morphology and crosslink structure of the powder  

NASA Astrophysics Data System (ADS)

The aim of this work was the preparation and characterization of polybutadiene rubber (BR) powder by irradiating of rubber lattices using 60Co radiation and spray-drying of them at the appropriate condition. The influences of absorbed dose on the volume swelling ratio, molecular weight between crosslinks, gel fraction, and glass transition temperature of obtained powder were studied. Morphology, size and size distribution of rubber particles were examined by using scanning electron microscopy (SEM) and laser particle size analyzer (LPSA) technique, respectively. Results obtained by LPSA revealed that radiation has no effect on particle size of rubber latex but after drying, adherence properties of rubber particle causes increase in particle size of rubber powder, as shown in SEM photograph. Fourier transform infrared spectroscopy of rubber powders confirmed that with increasing the irradiation dose, characteristic peak corresponds to the >CC< double bands decreased. Also Charlesby-Pinner equation was used to evaluate radiation yield.

Rezaei Abadchi, Majid; Jalali-Arani, Azam

2014-02-01

461

30 CFR 75.1101-14 - Installation of dry powder chemical systems.  

Code of Federal Regulations, 2010 CFR

...Self-contained dry powder chemical systems shall be...components of each dry powder chemical system shall be a type...or Factory Mutual Engineering Corp. (c) The components of each dry powder chemical system shall be...

2010-07-01

462

PLUTONIUM-HYDROGEN REACTION PRODUCT, METHOD OF PREPARING SAME AND PLUTONIUM POWDER THEREFROM  

Microsoft Academic Search

A process is described for forming plutonlum hydride powder by reacting ; hydrogen with massive plutonium metal at room temperature and the product ; obtained. The plutonium hydride powder can be converted to plutonium powder by ; heating to above 200 deg C.

S. Fried; H. L. Baumbach

1959-01-01

463

40 CFR 471.100 - Applicability; description of the powder metals subcategory.  

Code of Federal Regulations, 2010 CFR

... false Applicability; description of the powder metals subcategory. 471.100 Section 471.100 Protection... EFFLUENT GUIDELINES AND STANDARDS NONFERROUS METALS FORMING AND METAL POWDERS POINT SOURCE CATEGORY Metals Powders...

2010-07-01

464

Homogeneous Precipitation of Nickel Hydroxide Powders  

SciTech Connect

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 urea precipitation method. Model predictions on Ni{sup 2+} precipitation rate were confirmed with precipitation experiments carried out at 90 C. Experimental data and model predictions were in remarkable agreement. Uncertainty in the solubility product data of nickel hydroxides was found to be the large contributor to the error. There were demonstrable compositional variations across the particle cross-sections and the growth mechanism was determined to be the aggregation of primary crystallites. This implied that there is a change in the intercalate chemistry of the primary crystallites with digestion time. Predicted changes in the concentrations of simple and complex ions in the solution support the proposed mechanism. The comprehensive set of hydrolysis reactions used in the model described above allows the investigation of other systems provided that accurate reaction constants are available. the fact that transition metal ions like Ni{sup 2+} form strong complexes with ammonia presents a challenge in the full recovery of the Ni{sup 2+}. On the other hand, presence of Al{sup 3+} facilitates the complete precipitation of Ni{sup 2+} in about 3 hours of digestion. A challenge in their predictive modeling studies had been the fact that simultaneous incorporation of more than one metal ion necessitates a different approach than just using the equilibrium constants of hydrolysis, complexation and precipitation reactions. Another limitation of using equilibrium constants is that the nucleation stage of digestion, which is controlled mainly by kinetics, is not fully justified. A new program released by IBM Almaden Research Center (Chemical Kinetics Simulator{trademark}, Version 1.01) lets the user change the order of kinetic components of a reaction which was set to stoichiometric constant with which the species appear in the reaction in KINSIM by default. For instance, in the case of LDH precipitation, the new program allows to change the order of species in the reactions associated with Al{sup 3+} and let the Ni{sup 2+} reactions take over. This could be carried on iteratively until a good fit between the experimental data and the predictions were observed. However for such studies availability of accurate equilibrium constants (especially for the solubility products for the solid phase) is a prerequisite.

Bora Mavis

2003-12-12

465

A comparison of the sintering of various titanium powders  

SciTech Connect

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

Gerdemann, Stephen J.; Alman, David E.

2005-02-01

466

[Effect of Xiaoer Fuxie Waifu powder on gastrointestinal dynamics].  

PubMed

To explore the effect of Xiaoer Fuxie Waifu powder on gastrointestinal dynamics. In the study, the charcoal powder propelling test was used to observe the effect Xiaoer Fuxie Waifu powder on the intestinal motility of normal mice and deficient diarrheal mice. The results showed that Xiaoer Fuxie Waifu powder had no obvious inhibitory effect on the powder propelling in normal mice, but a remarkable inhibitory effect on deficient diarrheal mice. Afterwards, diarrhea index was used to observe the effect on deficient diarrheal mice. The results showed a good anti-diarrhea effect in deficient diarrheal mice induced by folium sennae. According to the subsequent isolated intestines smooth muscle test, Xiaoer Fuxie Waifu powder showed a competitive antagonism on muscular tension caused by acetyl choline and barium chloride, as well as a certain synergistic action with atropine. Finally, the method of radio-immunity was used to determine the contents of SP and VIP in small intestine of mice, showing that SP and VIP in small intestine of mice were decreased and the motility of intestine was inhibited. In conclusion, both in vitro and in vivo experiments indicate that Xiaoer Fuxie Waifu powder is a good traditional Chinese gastrointestinal dynamic medicine for external application, with an anti-diarrhea effect on diarrhea mice induced by spleen deficiency and diarrhea. PMID:24199580

Liu, Hui-Min; Liu, Li; Liu, Qiang

2013-07-01

467

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

SciTech Connect

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

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

2012-03-31

468

The structure-property relationships of powder processed Fe-Al-Si alloys  

SciTech Connect

Iron-aluminum alloys have been extensively evaluated as semi-continuous product such as sheet and bar, but have not been evaluated by net shape P/M processing techniques such as metal injection molding. The alloy compositions of iron-aluminum alloys have been optimized for room temperature ductility, but have limited high temperature strength. Hot extruded powder alloys in the Fe-Al-Si system have developed impressive mechanical properties, but the effects of sintering on mechanical properties have not been explored. This investigation evaluated three powder processed Fe-Al-Si alloys: Fe-15Al, Fe-15Al-2.8Si, Fe-15Al-5Si (atomic %). The powder alloys were produced with a high pressure gas atomization (HPGA) process to obtain a high fraction of metal injection molding (MIM) quality powder (D{sub 84} < 32 {micro}m). The powders were consolidated either by P/M hot extrusion or by vacuum sintering. The extruded materials were near full density with grain sizes ranging from 30 to 50 {micro}m. The vacuum sintering conditions produced samples with density ranging from 87% to 99% of theoretical density, with an average grain size ranging from 26 {micro}m to 104 {micro}m. Mechanical property testing was conducted on both extruded and sintered material using a small punch test. Tensile tests were conducted on extruded bar for comparison with the punch test data. Punch tests were conducted from 25 to 550 C to determine the yield strength, and fracture energy for each alloy as a function of processing condition. The ductile to brittle transition temperature (DBTT) was observed to increase with an increasing silicon content. The Fe-15Al-2.8Si alloy was selected for more extensive testing due to the combination of high temperature strength and low temperature toughness due to the two phase {alpha} + DO{sub 3} structure. This investigation provided a framework for understanding the effects of silicon in powder processing and mechanical property behavior of Fe-Al-Si alloys.

Prichard, P.D.

1998-02-23

469

Coal-powder characterization and thermal analysis  

SciTech Connect

The laser, which produces extremely fast heating rates, initiates primary pyrolysis reactions that are effectively quenched after a pulse, thus minimizing secondary reactions. A continuous (cw) CO/sub 2/ laser has been used to pyrolyze crushed coal samples in a helium atmosphere. The unsieved coal used in the experiments is characterized to define an average particle diameter and the distribution of diameters. This statistical information is used in several finite element numerical models to predict the temperatures and heating rates that occur in the sample and in individual particles during an experiment. The calculation of the peak temperature reached on the sample surface correlates well with experimental measurements. The numerical model predicts the correct shape of the temperature fields but does not account for differences observed in the amount of coal undergoing pyrolysis as a function of average particle diameter. Scanning electron microscopic (SEM) examination of coal samples after laser pyrolysis indicates that the powder cannot be accurately modeled as a single-phase continuum, but must be considered on a smaller, or particle level scale. Trends predicted in the idealized coal particle models are confirmed with the SEM observation.

Bennett, G.; Luther, M.

1982-01-01

470

Micro-mechanical modelling of powder compaction  

NASA Astrophysics Data System (ADS)

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

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

2001-04-01

471

Powder metallurgy process for manufacturing core projectile  

NASA Astrophysics Data System (ADS)

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

Akbar, Taufik; Setyowati, Vuri Ayu; Widyastuti

2013-09-01

472

Pulsed Neutron Powder Diffraction for Materials Science  

NASA Astrophysics Data System (ADS)

The accelerator-based neutron diffraction began in the end of 60's at Tohoku University which was succeeded by the four spallation neutron facilities with proton accelerators at the High Energy Accelerator Research Organization (Japan), Argonne National Laboratory and Los Alamos Laboratory (USA), and Rutherford Appleton Laboratory (UK). Since then, the next generation source has been pursued for 20 years, and 1MW-class spallation neutron sources will be appeared in about three years at the three parts of the world: Japan, UK and USA. The joint proton accelerator project (J-PARC), a collaborative project between KEK and JAEA, is one of them. The aim of the talk is to describe about J-PARC and the neutron diffractometers being installed at the materials and life science facility of J-PARC. The materials and life science facility of J-PARC has 23 neutron beam ports and will start delivering the first neutron beam of 25 Hz from 2008 May. Until now, more than 20 proposals have been reviewed by the review committee, and accepted proposal groups have started to get fund. Those proposals include five polycrystalline diffractometers: a super high resolution powder diffractometer (SHRPD), a 0.2%-resolution powder diffractometer of Ibaraki prefecture (IPD), an engineering diffractometers (Takumi), a high intensity S(Q) diffractometer (VSD), and a high-pressure dedicated diffractometer. SHRPD, Takumi and IPD are being designed and constructed by the joint team of KEK, JAEA and Ibaraki University, whose member are originally from the KEK powder group. These three instruments are expected to start in 2008. VSD is a super high intensity diffractometer with the highest resolution of ?d/d = 0.3%. VSD can measure rapid time-dependent phenomena of crystalline materials as well as glass, liquid and amorphous materials. The pair distribution function will be routinely obtained by the Fourier transiformation of S(Q) data. Q range of VSD will be as wide as 0.01 -1powder diffraction. IPD covers d range 0.15

Kamiyama, T.

2008-03-01

473

Morphology and composition of Ni-Co electrodeposited powders  

SciTech Connect

The morphology, phase and chemical composition of Ni-Co alloy powders electrodeposited from an ammonium sulfate-boric acid containing electrolyte with different ratio of Ni/Co ions were investigated. The ratios of Ni/Co ions were 1/1, 1/2 and 1/3. The morphology, chemical composition and phase composition of the electrodeposited alloy powders were investigated using AES, SEM, EDS and XRD analysis. Composition of the electrolyte, i.e. the ratio of Ni/Co concentrations was found to influence both, the alloy phase composition and the morphology of Ni-Co alloy powders. At the highest ratio of Ni/Co = 1/1 concentrations typical 2D fern-like dendritic particles were obtained. With a decrease of Ni/Co ions ratio among 2D fern-like dendrites, 3D dendrites and different agglomerates were obtained. X-ray diffraction studies showed that the alloy powders mainly consisted of the face-centered cubic {alpha}-nickel phase and hexagonal close-packed {epsilon}-cobalt phase and minor proportions of face-centered cubic {alpha}-cobalt phase. The occurrence of the latter phase was observed only in the alloy powder with the higher cobalt concentration in electrolyte. The electrodeposition of Ni-Co powders occurred in an anomalous manner. - Highlights: Black-Right-Pointing-Pointer Ni-Co alloys powders were successfully electrodeposited. Black-Right-Pointing-Pointer Composition of the electrolyte (Ni/Co ions ratio) was found to influence on morphology of powders. Black-Right-Pointing-Pointer The electrodeposition of Ni-Co powders occurred in an anomalous manner.

Maksimovic, V.M., E-mail: vesnam@vinca.rs [Institute of Nuclear Sciences, 'Vinca', University of Belgrade, 11001 Belgrade, P. O. Box 522 (Serbia); Lacnjevac, U.C. [Institute for Multidisciplinary research, University of Belgrade, P.O. Box 33, 11030 Belgrade (Serbia); Stoiljkovic, M.M. [Institute of Nuclear Sciences, 'Vinca', University of Belgrade, 11001 Belgrade, P. O. Box 522 (Serbia); Pavlovic, M.G. [Institute of Electrochemistry, ICTM, University of Belgrade, 11000 Belgrade, Njegoseva 12 (Serbia); Jovic, V.D. [Institute for Multidisciplinary research, University of Belgrade, P.O. Box 33, 11030 Belgrade (Serbia)

2011-12-15

474

Equilibrium binding studies of mono, di and triisocyanide ligands on Au powder surfaces  

SciTech Connect

The author`s group has previously shown that isocyanides are readily adsorbed from solutions to Au powder and bind to the Au surface in an end-on fashion through the terminal carbon. Later work demonstrated that the equilibrium constants for the reversible adsorption of electronically inequivalent isocyanides could be obtained using the Langmuir isotherm technique. This dissertation describes two projects completed which complement the initial findings of this group. Initially, several alkylisocyanides were synthesized to examine the effect of tail length on Au powder adsorption. It was observed that the length of the alkyl chain affected not only the Au surface binding affinity, but also the rate of surface saturation and saturation coverage values. Direct competition studies were also studied using a {sup 13}C-labeled isocyanide. These studies demonstrated the stabilization afforded by substrate-substrate packing forces in SAM`s formed by the longer chain isocyanides. In a second study, di and triisocyanides were synthesized to determine the effect that the length of the connecting link and the number of isocyanide groups (as points of attachment) have on Au adsorption stability. The work in this area describes the binding modes, relative binding affinities and surface coverage values for a series of flexible alkyl and xylyldiisocyanides on Au powder surfaces. This report contains only the introductory material, and general summary. Two chapters have been processed separately. 56 refs.

Ontko, A.

1997-10-08

475

Toward intradermal vaccination: preparation of powder formulations by collapse freeze-drying.  

PubMed

Intradermal powder immunization is an emerging technique in vaccine delivery. The purpose of this study was to generate powder particles for intradermal injection by freeze-drying and subsequent cryo-milling. Two different freeze-drying protocols were compared, a moderate freeze-drying cycle and an aggressive freeze-drying cycle, which induced a controlled collapse of the sugar matrix. Ovalbumin served as model antigen. The influence of collapse drying and cryo-milling on particle morphology and protein stability was investigated. Cryo-milling generated irregularly shaped particles of size 20-70?祄. The recovery of soluble monomer of ovalbumin was not changed during freeze-drying and after cryo-milling, or after 12 months of storage at 2-8?癈. A slight increase in higher molecular weight aggregates was found in formulations containing the polymer dextran after 12 months of storage at 50?癈. Light obscuration measurements showed an increase in cumulative particle counts after cryo-milling that did not further increase during storage at 2-8?癈 for 12 months. The applicability of the cryo-milling process to other therapeutic proteins was shown using recombinant human granulocyte-colony stimulating factor. Collapse freeze-drying and subsequent cryo-milling allows the generation of particles suitable for intradermal powder injection. PMID:23432539

Etzl, Elsa E; Winter, Gerhard; Engert, Julia

2014-03-01

476

Fabrication and Properties of Thermal Sprayed AlSi-Based Coatings from Nanocomposite Powders  

NASA Astrophysics Data System (ADS)

AlSi-based nanocomposite powders (where nanoparticles were TiO2, ZrO2, and Al2O3 and the amount of reinforcement was 2.5, 5, and 10 wt.%) were made by ball milling and then thermal sprayed using low velocity oxy-fuel technique. The AlSi-based nanocomposite powders had nanosized ceramic reinforcement adhered to the surface of the powders after ball milling. The AlSi-based coatings had the typical thermal spray microstructure where lamellae, oxide layers, unmelted particles, and pores could be seen. Submicron second phase in the form of agglomerates, molten splats, or unmelted particles between AlSi lamellae could be observed as well. Hardness and porosity of the coatings increased when more ceramic second phase particles (harder than AlSi) were added. Sliding wear tests were carried out in pin-on-disk geometry. The wear tracks of AlSi and AlSi-based coatings show plastic deformation as the main material removal mechanism during the sliding wear test. The sliding wear rate of the coatings decreased as more second phase ceramic particles were added. It was due to an increase in the hardness and a decrease in the friction coefficient of the coatings.

Limpichaipanit, A.; Banjongprasert, C.;