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1

[Otologic diagnosis: powder technique].  

PubMed

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

Tolsdorff, P

2011-06-01

2

Second harmonic generation by micropowders: a revision of the Kurtz-Perry method and its practical application  

NASA Astrophysics Data System (ADS)

We theoretically study the second harmonic generation by powder crystal monolayers and by thick samples of crystalline powder with particle size in the range of microns. Contrary to usual treatments, the light scattering by the particles is explicitly introduced in the model. The cases of powder in air and in an index-matching liquid under the most common experimental geometries are considered. Special attention is paid to the possibility of determining the value of some nonlinear optical coefficients from the experiments. The limitations and shortcomings of the classical Kurtz and Perry method (Kurtz and Perry in J Appl Phys 39:3798, 1968) and the most common practical misuses of it are discussed. It is argued that many of the experimental works based on that method oversimplify the technique and contain important errors. In order to obtain reliable values of the nonlinear coefficients, an appropriate experimental configuration and analysis of the data are pointed out. The analysis is especially simple in the case of uniaxial phase-matchable materials for which simple analytical expressions are derived.

Aramburu, I.; Ortega, J.; Folcia, C. L.; Etxebarria, J.

2014-07-01

3

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

4

Gary M. Kurtz Assistant Commander for Corporate Operations  

E-print Network

for the Naval Air Systems Command (NAVAIR) in Patuxent River, Maryland. Mr. Kurtz is responsible for the full array of NAVAIR command business operations including command administration, total force management and has over 28 years of distinguished Federal service. Mr. Kurtz began his career with NAVAIR in 1984

5

Densification of powder metallurgy billets by a roll consolidation technique  

NASA Technical Reports Server (NTRS)

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

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

1973-01-01

6

Physical and chemical characterization techniques for metallic powders  

NASA Astrophysics Data System (ADS)

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.; Stutzman, P. E.; Ferraris, C. F.; Watson, S. S.; Peltz, M. A.; Garboczi, E. J.

2014-02-01

7

Application of physical and chemical characterization techniques to metallic powders  

NASA Astrophysics Data System (ADS)

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.; Watson, S. S.; Stutzman, P. E.; Ferraris, C. F.; Peltz, M. A.; Garboczi, E. J.

2014-02-01

8

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

9

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

Microsoft Academic Search

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

J. Suwanprateeb; R. Sanngam; T. Panyathanmaporn

2010-01-01

10

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

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

12

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 pyrite sulfur (Spy) and organic carbon (Corg) burial rates from recently improved Cenozoic stable isotope. However, we find that the major early Cenozoic peak in Corg burial coincides with a minimum in Spy burial

Zachos, James

13

Synthesis and characterization of zinc titanate nano-crystal powders by sol–gel technique  

Microsoft Academic Search

A sol–gel technique including the Pechini process has been employed for the preparation of nano-sized zinc titanate (ZnTiO3) powders. The yielding powders were heated at temperature from 500°C to 1000°C for various times. The ZnTiO3 phase was formed at the beginning of 500°C. The shape of crystalline will be changed from granular to fiber as the calcination temperature increasing from

Yee-Shin Chang; Yen-Hwei Chang; In-Gann Chen; Guo-Ju Chen; Yin-Lai Chai

2002-01-01

14

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

SciTech Connect

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

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

1999-07-21

15

Preparation of nanosized metal-oxide ultrafine powders by atomizing-combustion technique  

Microsoft Academic Search

The nano-sized metal-oxide ultrafine powders of the low-melting-point metals can be prepared rapidly using a new atomizing\\u000a - combustion technique by which the superheated metal melt was atomized with a ceramic atomizing-burner first through the\\u000a medium of high pressure oxygen, then the metal fog burned up in a combustion chamber. Based on the experiments, nano-sized\\u000a SnO2, In2O3 and Bi2O3 powders

Shizhu Chen; Zhimin Yin

1998-01-01

16

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

17

Microstructural response of rapidly solidified 304 stainless steel powder to three consolidation techniques  

SciTech Connect

Some of the characteristics of rapidly solidified metals, such as reduced chemical segregation and extremely fine grain size, can result in improved material properties and performance. However, these same characteristics present a challenge to the metallographer examining the microstructures of these materials, and frequently more than one technique is required to characterize the features present. This paper describes the vastly different microstructure produced in centrifugally atomized 304 stainless steel powder after consolidation by three different processes: hot isostatic pressing, extrusion, and explosive consolidation. Characterization of microstructural features depended upon a combination of optical, scanning electron, and transmission electron techniques.

Miley, D.V.; Flinn, J.E.; Fletcher, G.L.

1986-01-01

18

Preparation and in vitro characterization of piroxicam enteric coated pellets using powder layering technique.  

PubMed

The objective of this study was to develop piroxicam enteric coated pellets using nonpareil seeds by powder layering technique to minimize its gastrointestinal adverse effects. Inert seeds were prepared by incorporating sugar, Avicel PH 101 and lactose. The obtained cores were then treated by PVP 10 w/v % solution using centrifugal granulator (CF-granulator) and then coated with micronized piroxicam using HPMC solution (8 w/v %) as binder. The piroxicam pellets were finally coated with different polymers (Eudragit L30D-55, Eudragit L100, Eudragit NE30D, Acryleze, or mixture of Eudragits L30D-55 and NE30D) and plasticizers (triethyl citrate and polyethylene glycol 6000). Results showed that Eudragit L30D-55 with 3% weight gain accompanied with TEC produced suitable enteric coated pellets. PMID:19519183

Varshosaz, Jaleh; Tavakoli, Naser; Serri, Azadeh

2009-01-01

19

kurtz, a novel nonvisual arrestin, is an essential neural gene in Drosophila.  

PubMed Central

The kurtz gene encodes a novel nonvisual arrestin. krz is located at the most-distal end of the chromosome 3R, the third gene in from the telomere. krz is expressed throughout development. During early embryogenesis, krz is expressed ubiquitously and later is localized to the central nervous system, maxillary cirri, and antennal sensory organs. In late third instar larvae, krz message is detected in the fat bodies, the ventral portion of the thoracic-abdominal ganglia, the deuterocerebrum, the eye-antennal imaginal disc, and the wing imaginal disc. The krz(1) mutation contains a P-element insertion within the only intron of this gene and results in a severe reduction of function. Mutations in krz have a broad lethal phase extending from late embryogenesis to the third larval instar. The fat bodies of krz(1) larva precociously dissociate during the midthird instar. krz(1) is a type 1 melanotic tumor gene; the fat body is the primary site of melanotic tumor formation during the third instar. We have functionally rescued these phenotypes with both genomic and cDNA transgenes. Importantly, the expression of a full-length krz cDNA within the CNS rescues the krz(1) lethality. These experiments establish the krz nonvisual arrestin as an essential neural gene in Drosophila. PMID:10880488

Roman, G; He, J; Davis, R L

2000-01-01

20

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

21

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

NASA Technical Reports Server (NTRS)

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

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

1992-01-01

22

Development of a powder metallurgical technique for the mass production of carat gold wedding rings  

Microsoft Academic Search

The development is traced of a press and sinter, powder metallurgical process for the production of carat gold wedding rings.\\u000a The paper includes experimental data on powder production, powder pressing and sintering as well as details of the production\\u000a process now fully adopted for the mass production of rings. Properties of the new rings compare favourably with those produced\\u000a by

Peter M Raw

2000-01-01

23

Processing of a porous titanium alloy from elemental powders using a solid state isothermal foaming technique  

Microsoft Academic Search

The authors have conducted a preliminary investigation with regard to the potential to manufacture porous titanium alloys\\u000a for biomedical applications using toxic-free elemental powders, i.e., Ti, Nb, Ta, Zr, in combination with the pressurised\\u000a gas bubble entrapment method and in contrast to standard processing routes that generally utilise prealloyed powder containing\\u000a potentially toxic elements. Elemental powder compacts were either hot

Aris W. Nugroho; Garry Leadbeater; Ian J. Davies

2010-01-01

24

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

25

Investigation of a high pressure implosive technique for metal powder compaction  

E-print Network

ball bearing introduced into the test to study mode of fai. lure. Figure 22 shows the fracture patterns. Figure 23 shows an ampoule of non-metallic material de- posited in the powdered iron specimen. 28 5. 90 g~ 7. M AQQK8. 22* PFSCCVX8 32... ball bearing introduced into the test to study mode of fai. lure. Figure 22 shows the fracture patterns. Figure 23 shows an ampoule of non-metallic material de- posited in the powdered iron specimen. 28 5. 90 g~ 7. M AQQK8. 22* PFSCCVX8 32...

Garrett, Donald Richard

2012-06-07

26

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.; Günes, M.; Gümüs, S.; Kacar, E.; Gundogdu, O.; Zeren, M.; Demir, A.

2013-02-01

27

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

28

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

NASA Astrophysics Data System (ADS)

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

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

2012-01-01

29

Chemiluminescence measurements on irradiated garlic powder by the single photon counting technique  

NASA Astrophysics Data System (ADS)

The feasibility of identifying irradiated garlic powder measuring chemiluminescence by liquid scintillation spectrometry was studied. Samples packed in 100 ?m thick polyethylene bags were irradiated in a 60Co semi-industrial facility, with doses of 10 and 30 kGy. Control and irradiated samples were stored at 20 ± 4°C and 70 ± 10% RH in darkness for 2 years. Assays were performed to establish the best sample concentration and pH of the buffer solution in which garlic powder was to be suspended for its measurement. The water content of garlic samples was also analyzed throughout storage time, as it related to the stability of the species causing luminescence. Chemiluminescence values diminished in every sample over storage time following an exponential pattern. Irradiated samples showed values significantly higher than those of the control samples, according to the radiation dose, throughout the storage period. This does not necessarily imply that the identification of the irradiated samples would be certain, since values of control samples coming from different origins have been found to fluctuate within a rather wide range. Nonetheless, in principle, the method looks promising for the measurement of chemiluminescence in irradiated samples

Narvaiz, P.

1995-02-01

30

New technique for the direct analysis of food powders confined in a small hole using transversely excited atmospheric CO(2) laser-induced gas plasma.  

PubMed

Taking advantage of the differences between the interactions of transversely excited atmospheric (TEA) CO(2) lasers with metal and with organic powder, a new technique for the direct analysis of food powder samples has been developed. In this technique, the powder samples were placed into a small hole with a diameter of 2 mm and a depth of 3 mm and covered by a metal mesh. The TEA CO(2) laser (1500 mJ, 200 ns) was focused on the powder sample surfaces, passing through the metal mesh, at atmospheric pressure in nitrogen gas. It is hypothesized that the small hole functions to confine the powder particles and suppresses the blowing-off of sample, while the metal mesh works as the source of electrons to initiate the strong gas breakdown plasma. The confined powder particles are then ablated by laser irradiation and the ablated particles move into the strong gas breakdown plasma region to be atomized and excited; this method cannot be applied for the case of Nd:YAG lasers because in such case the metal mesh itself was ablated by the laser irradiation. A quantitative analysis of a milk powder sample containing different concentrations of Ca was successfully demonstrated, resulting in a good linear calibration curve with high precision. PMID:19094393

Khumaeni, Ali; Ramli, Muliadi; Deguchi, Yoji; Lee, Yong Inn; Idris, Nasrullah; Kurniawan, Koo Hendrik; Lie, Tjung Jie; Kagawa, Kiichiro

2008-12-01

31

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

32

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

NASA Technical Reports Server (NTRS)

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

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

1987-01-01

33

Observation of localized heating phenomena during microwave heating of mixed powders using in situ x-ray diffraction technique  

NASA Astrophysics Data System (ADS)

In materials processing research using microwave heating, there have been several observations of various phenomena occurring known as microwave effects. One significant example of such a phenomenon is increased reaction kinetics. It is believed that there is a possibility that this might be caused by localized heating, were some reactants would attain a higher than apparent temperature. To examine whether such thermal gradients are indeed possible, mixed powders of two microwave non-absorbers, alumina and magnesia, were mixed with graphite, a known absorber, and heated in a microwave furnace. During microwave irradiation, the local temperatures of the respective sample constituents were measured using an in situ x-ray diffraction technique. In the case of the alumina and graphite sample, a temperature difference of around 100 °C could be observed.

Sabelström, N.; Hayashi, M.; Watanabe, T.; Nagata, K.

2014-10-01

34

Microstructural response of rapidly solidified 304 stainless steel powder to three consolidation techniques  

Microsoft Academic Search

Some of the characteristics of rapidly solidified metals, such as reduced chemical segregation and extremely fine grain size, can result in improved material properties and performance. However, these same characteristics present a challenge to the metallographer examining the microstructures of these materials, and frequently more than one technique is required to characterize the features present. This paper describes the vastly

D. V. Miley; J. E. Flinn; G. L. Fletcher

1986-01-01

35

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

Microsoft Academic Search

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

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

2008-01-01

36

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

37

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

38

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

39

Micromechanical Properties, Phase Composition, and Microstructure of Ceramics Prepared from Composite Powder (SiC – C) – Si 3 N 4 Using Different Techniques for Introduction of Sintering Activators  

Microsoft Academic Search

Mixtures based on a nanocomposite powder (SiC – C) for hot pressure molding of ceramics are prepared. Micromechanical properties of the sintered ceramics are shown to depend on the technique by which the sintering activator is introduced to the mixture. Results of a study of the structure and phase composition of the sintered ceramics by transmission electron microscopy and x-ray

N. K. Davidchuk; N. F. Gadzyra; G. G. Gnesin

2003-01-01

40

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

41

Synthesis, growth and characterization of non linear optical Bisthiourea ammonium chloride single crystals by slow evaporation technique  

NASA Astrophysics Data System (ADS)

A new semi-organic nonlinear optical crystal of Bisthiourea Ammonium Chloride (BTAC) has been grown by slow evaporation technique. The crystal system and lattice parameters were determined from X-ray diffraction. Fourier Transform Infrared (FTIR) studies confirm the various functional groups present in the grown crystal. The transmittance and absorbance of electromagnetic radiation is studied through UV-Visible spectrum. The thermal behavior of the grown crystals has been investigated by TG/DTA analysis. The dielectric constant and dielectric loss has been studied as a function of frequency for various temperatures and the result were discussed in detail. The SEM analysis was also done and it revealed the surface morphology of BTAC crystal. The second harmonic generation has been confirmed by the Kurtz powder test and it is found to be 1.4 times more than that of KDP crystal.

Ilango, E.; Rajasekaran, R.; Shankar, K.; Krishnan, S.; Chithambaram, V.

2014-11-01

42

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

43

Synthesis, optical and thermal studies on novel semi organic nonlinear optical Urea Zinc Acetate crystals by solution growth technique for the applications of optoelectronic devices  

NASA Astrophysics Data System (ADS)

Urea Zinc Acetate (UZA), a novel semi organic nonlinear optical crystal having dimensions 30×28×10 mm3 has been synthesized using slow evaporation technique. The lattice parameters for the grown crystals were determined using single crystal XRD. The presence of functional groups for the grown crystals was confirmed using Fourier Transform Infrared (FT-IR) spectroscopy. The optical absorption studies show that the material has wide optical transparency in the entire visible region. The thermal stability of the crystal was determined from thermo gravimetric and differential thermal analysis curve. The second harmonic generation was confirmed by Kurtz powder method and it is found to be 3 times than that of KDP crystal.

Chithambaram, V.; Krishnan, S.

2014-02-01

44

Enhanced oral bioavailability of novel mucoadhesive pellets containing valsartan prepared by a dry powder-coating technique.  

PubMed

The aim of this study was to develop novel mucoadhesive pellets containing valsartan (VAL) with enhanced oral bioavailability. Two types of VAL loaded core pellets were prepared by an extrusion/spheronization method, and further dry-coated with a mixture of hydroxypropylmethylcellulose (HPMC) and carbomer (CB) at different ratios. The effects of the pellet core composition, HPMC:CB ratio and coating level on the drug release from the coated pellets were investigated. The physicochemical properties of the core and coated pellets were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FT-IR). In addition, the in vitro and in vivo mucoadhesion properties as well as the bioavailability of the coated pellets in rats were evaluated by using VAL suspension and core pellets as control preparations. The results of the release study demonstrated that the two types of core pellets, especially the pellets formulated with a solubilizer and a pH modulator gave considerably faster drug release than the VAL powder. However, the core and coated pellets exhibited similar release profiles indicating that the dry powder-coating did not retard the drug release. Strong molecular interactions were observed between the drug and the carriers in FT-IR analysis. The coated pellets displayed distinct mucoadhesive property in vitro and delayed gastrointestinal (GI) transit in vivo. Furthermore, the coated pellets exhibit significantly higher AUC(0-12h) and C(max), as compared to the core pellets and drug suspension. It was concluded that the mucoadhesive pellets could render poorly water soluble drugs like VAL with a rapid drug release, delayed GI transit and enhanced oral bioavailability. PMID:22688251

Cao, Qing-Ri; Liu, Yan; Xu, Wei-Juan; Lee, Beom-Jin; Yang, Mingshi; Cui, Jing-Hao

2012-09-15

45

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

46

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

47

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.

48

Resin Powder Slurry Process for Composite Fabrication  

NASA Technical Reports Server (NTRS)

Potentially useful process for fabrication of fiber-reinforced resinmatrix composites is powder slurry technique. Applicability of technique demonstrated using powdered resin made from thermoplastic polyimide LaRC/ TPI (thermoplastic polyimide). Use of process circumvents need for such high-cost organic solvents as N-methylpyrrolidinone and diglyme (diglycol methyl ether). Two basic slurries for LaRC/TPI powder investigated.

Mike, R. A.

1986-01-01

49

Shear consolidation of powders  

NASA Astrophysics Data System (ADS)

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

Hanna, James A.

50

Investigations of BaxSr1-xTiO3 ceramics and powders prepared by direct current arc discharge technique  

NASA Astrophysics Data System (ADS)

BaxSr1-xTiO3 ceramics with x ranging from 0 to 1 were prepared by direct current arc discharge technique and studied by means of x-ray diffraction (XRD) and Raman spectroscopy. The cubic-tetragonal ferroelectric phase transition in BaxSr1-xTiO3 ceramics was found to occur at x ? 0.75. XRD investigation of as-grown BaTiO3 ceramics revealed co-existence of tetragonal and hexagonal modifications with a small amount of impurity phase BaTi4O9. No evidences of hexagonal phase were observed in Raman spectra of as-grown BaTiO3 ceramics, while Raman peaks related to hexagonal phase were clearly observed in the spectrum of fine-grain powders prepared from the same ceramics. A core-shell model for BaTiO3 ceramics prepared by direct current arc discharge technique is proposed. Absence of the hexagonal phase in any BaxSr1-xTiO3 solid solution with x < 1 is discussed in the frame of specific atomic arrangement.

Li, Shuangbin; Yao, Ying; Yuzyuk, Yu. I.; Jia, Yongzhong; Wang, Xiaohan; Xie, Shaolei; Jing, Yan

2014-09-01

51

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�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�E, and G75.78+0.34�H 2 O. The density profiles

Testi, Leonardo

52

Laser powder deposition  

Microsoft Academic Search

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

Lino Costa; Rui Vilar

2009-01-01

53

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

54

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

E-print Network

with Disabilities Act of 1990 are the Vice President for Student Affairs and the Equal Opportunity Compliance technology centers. The TBR system enrolls more than 80 percent of all Tennessee students attending public, or disability. The University does not discriminate on these bases in recruitment and admission of students

Dasgupta, Dipankar

55

Polymer powder prepregging: Scoping study  

NASA Technical Reports Server (NTRS)

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

Throne, James L.

1988-01-01

56

CURRICULUM VITAE Andrew C. Kurtz  

E-print Network

's biogeochemical cycles: Modeling the carbon cycle on geologic timescales, relative importance of marine and terrestrial organic carbon burial, role of fire, coupling between biogeochemical cycles of carbon, sulfur Center 10/99-8/01 Research: Evolution of Earth's carbon, sulfur, and silica cycles Supervisors: Lee R

Hutyra, Lucy R.

57

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

PubMed

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

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

2011-07-01

58

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

59

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

60

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

61

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

62

SHOCK COMPRESSION PROCESSING OF POWDERS  

Microsoft Academic Search

Shock compression processing is emerging as a novel technique for fabrication of esoteric materials. Not only can metal and ceramic powders be dynamically consolidated, but both equilibrium and non-equilibrium structures can be synthesized under the high pressure regime during the passage of shock waves of sufficient magnitude and duration. The shock waves can be generated by impact from a plate

N. N. Thadhani

1988-01-01

63

Pharmaceutically Engineering Powders Using FHMG  

Microsoft Academic Search

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

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

2007-01-01

64

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

SciTech Connect

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

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

2011-03-15

65

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

66

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

67

Electrical Conductivity of Metal Powders under Shock Compression  

Microsoft Academic Search

The electrical conductivity of a series of metal powders under shock compression is measured by an electrocontact technique. Initially, the metal particles are covered by an oxide film, and the powder is non-conducting. Under shock compression, the powder acquires macroscopic conductivity. The electrical conductivity of the shock-compressed powder depends substantially on the metal, porosity, particle size, and shock-wave pressure. The

S. D. Gilev

2005-01-01

68

Comment on ‘Analyzing floodplain policies using an interdependent land use allocation model’ by Lewis D. Hopkins, E. D. Brill, Jr., Kenneth B. Kurtz, and Harry G. Wenzel, Jr  

Microsoft Academic Search

The paper by Hopkins et al. [1981] describes an interesting technique for the analysis of flood plain policies using a land use allocation model. One of the simplifying assumptions used in their dynamic programing formulation involves the use of the 100-year flood elevation to estimate the range of flood damages from all storms, including those which are less frequent than

I. C. Goulter; D. A. Kiely

1983-01-01

69

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

70

Validity of particle size analysis techniques for measurement of the attrition that occurs during vacuum agitated powder drying of needle-shaped particles.  

PubMed

Analysis of needle-shaped particles of cellobiose octaacetate (COA) obtained from vacuum agitated drying experiments was performed using three particle size analysis techniques: laser diffraction (LD), focused beam reflectance measurements (FBRM) and dynamic image analysis. Comparative measurements were also made for various size fractions of granular particles of microcrystalline cellulose. The study demonstrated that the light scattering particle size methods (LD and FBRM) can be used qualitatively to study the attrition that occurs during drying of needle-shaped particles, however, for full quantitative analysis, image analysis is required. The algorithm used in analysis of LD data assumes the scattering particles are spherical regardless of the actual shape of the particles under evaluation. FBRM measures a chord length distribution (CLD) rather than the particle size distribution (PSD), which in the case of needles is weighted towards the needle width rather than their length. Dynamic image analysis allowed evaluation of the particles based on attributes of the needles such as length (e.g. the maximum Feret diameter) or width (e.g. the minimum Feret diameter) and as such, was the most informative of the techniques for the analysis of attrition that occurred during drying. PMID:22068605

Hamilton, Peter; Littlejohn, David; Nordon, Alison; Sefcik, Jan; Slavin, Paul

2012-01-01

71

Which Powder is It?  

NSDL National Science Digital Library

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

Sciencenter

2014-08-27

72

Powder-Metallurgy Process And Product  

NASA Technical Reports Server (NTRS)

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

Paris, Henry G.

1988-01-01

73

Structural characterization of Bi2Te3 and Sb2Te3 as a function of temperature using neutron powder diffraction and extended X-ray absorption fine structure techniques  

NASA Astrophysics Data System (ADS)

The structure of Bi2Te3 (Seebeck coefficient Standard Reference Material (SRM™ 3451)) and the related phase Sb2Te3 have been characterized as a function of temperature using the neutron powder diffraction (NPD) and the extended X-ray absorption fine structure (EXAFS) techniques. The neutron structural studies were carried out from 20 K to 300 K for Bi2Te3 and from 10 K to 298 K for Sb2Te3. The EXAFS technique for studying the local structure of the two compounds was conducted from 19 K to 298 K. Bi2Te3 and Sb2Te3 are isostructural, with a space group of R 3 ¯m. The structure consists of repeated quintuple layers of atoms, Te2-M-Te1-M-Te2 (where M = Bi or Sb) stacking along the c-axis of the unit cell. EXAFS was used to examine the bond distances and static and thermal disorders for the first three shells of Bi2Te3 and Sb2Te3 as a function of temperature. The temperature dependencies of thermal disorders were analyzed using the Debye and Einstein models for lattice vibrations. The Debye and Einstein temperatures for the first two shells of Bi2Te3 are similar to those of Sb2Te3 within the uncertainty in the data. However, the Debye and Einstein temperatures for the third shell of Bi-Bi are significantly lower than those of the third shell of Sb-Sb. The Einstein temperature for the third shell is consistent with a soft phonon mode in both Bi2Te3 and Sb2Te3. The lower Einstein temperature of Bi-Bi relative to Sb-Sb is consistent with the lower value of thermal conductivity of Bi2Te3 relative to Sb2Te3.

Mansour, A. N.; Wong-Ng, W.; Huang, Q.; Tang, W.; Thompson, A.; Sharp, J.

2014-08-01

74

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

75

Mathematical modeling of powder paint particle trajectories in electrostatic painting  

Microsoft Academic Search

The trajectories of charged powder particles in an electrostatic powder coating system were modeled considering electrical and fluid forces. The mathematical model employed an iterative technique wherein the charge simulation method was used to compute the electric field strength and the method of characteristics was used to compute the charge density in the gun-to-target region. The fluid flow between the

F. Sharmene Ali; Terence E. Base; Ion I. Inculet

2000-01-01

76

Mathematical modelling of powder paint particle trajectories in electrostatic painting  

Microsoft Academic Search

The trajectories of charged powder particles in an electrostatic powder coating system were modelled considering electrical and fluid forces. The mathematical model employed an iterative technique wherein the charge simulation method was used to compute the electric field strength and the method of characteristics was used to compute the charge density in the gun-to-target region. The fluid flow between the

F. S. Ali; T. E. Base; I. I. Inculet

1994-01-01

77

Powder metal matrix composites: selection and processing  

Microsoft Academic Search

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

M. J Tan; X Zhang

1998-01-01

78

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

79

Iowa Powder Atomization Technologies  

SciTech Connect

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

None

2012-01-01

80

Macromolecular powder diffraction : structure solution via molecular.  

SciTech Connect

Macromolecular powder diffraction is a burgeoning technique for protein structure solution - ideally suited for cases where no suitable single crystals are available. Over the past seven years, pioneering work by Von Dreele et al. [1,2] and Margiolaki et al. [3,4] has demonstrated the viability of this approach for several protein structures. Among these initial powder studies, molecular replacement solutions of insulin and turkey lysozyme into alternate space groups were accomplished. Pressing the technique further, Margiolaki et al. [5] executed the first molecular replacement of an unknown protein structure: the SH3 domain of ponsin, using data from a multianalyzer diffractometer. To demonstrate that cross-species molecular replacement using image plate data is also possible, we present the solution of hen egg white lysozyme using the 60% identical human lysozyme (PDB code: 1LZ1) as the search model. Due to the high incidence of overlaps in powder patterns, especially in more complex structures, we have used extracted intensities from five data sets taken at different salt concentrations in a multi-pattern Pawley refinement. The use of image plates severely increases the overlap problem due to lower detector resolution, but radiation damage effects are minimized with shorter exposure times and the fact that the entire pattern is obtained in a single exposure. This image plate solution establishes the robustness of powder molecular replacement resulting from different data collection techniques.

Doebbler, J.; Von Dreele, R.; X-Ray Science Division

2009-01-01

81

Comparative study of pure and alkaline earth metallic doped cadmium mercury thiocyanate single crystals—Gel technique  

NASA Astrophysics Data System (ADS)

Growth aspects of Ba and Ca doped cadmium mercury thiocyanate (CMTC) single crystals from silica gel by the process of diffusion are discussed. The incorporation of dopants in the crystal has been confirmed by inductively coupled plasma (ICP) analysis. Single crystal X-ray diffraction studies reveal the structures of the doped crystals to be tetragonal implying that the incorporation of the dopants has not changed the structure of the parent crystal. The diffraction planes were identified and indexed by powder diffraction analysis. High-resolution X-ray diffraction analyses were carried out to investigate the crystalline perfection of the grown crystals. The grown crystals were characterized by Fourier transform infrared and transmission spectral analyses. Vickers microhardness studies on the grown crystals reveal that they belong to soft material category. Employing powder Kurtz method, their second harmonic generation efficiencies were measured in comparison with urea.

Kalainathan, S.; Kumari, P. Nisha Santha

2009-07-01

82

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

83

Dielectric Constant of Powders  

Microsoft Academic Search

MEASUREMENTS have been made at 9,200 Mc\\/s to determine the dependence of dielectric constant of powder samples' packing densities. The net polarization P produced in a substance in an electric field consists of the contributions of electronic, atomic and dipolar polarizations. It is related to the dielectric constant by Clausius-Masotti relation: where K = (? - l)\\/(? + 2), M

Prem Swarup; R. P. Arora

1964-01-01

84

Spiral Powder Overlays  

E-print Network

Whether you encounter electron powder diffraction patterns everyday, or run across them only rarely, interpreting them may require a bit of preparation. But it's easy to lose track of the numbers for your microscope's camera constant, not to mention the bewildering array of lattice parameters and symmetries that one may encounter in the microscope. In that context, we describe

P. Fraundorf; Shuhan Lin

85

Sintering of Tin Powder  

Microsoft Academic Search

MOST powdered metals will sinter together appreciably when heated to a temperature which, in the absence of extraneous factors, is about three-quarters of their absolute melting point; metals of low melting point tend to be exceptions, however, to this generalization in that they can be heated nearly to their melting point before sintering takes place. There is no evidence, in

R. F. Smart; E. C. Ellwood

1958-01-01

86

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

87

Experiments on compression moulding and pultrusion of thermoplastic powder impregnated towpregs  

Microsoft Academic Search

Powder impregnation techniques have been developed to increase design and manufacturing flexibility with thermoplastic composites. The effect of pressure, temperature, mould closing rate and time on the consolidation of poly(ether ketone ketone) (PEKK) powder impregnated glass fibre towpregs in compression moulding were studied. A design of experiments approach was used. Isothermal pultrusion experiments using nylon 11 and PEKK powder impregnated

Karthik Ramani; Harshad Borgaonkar; Chris Hoyle

1995-01-01

88

Method to blend separator powders  

DOEpatents

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

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

2007-12-04

89

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

90

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

91

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

92

Powdering or spraying.  

PubMed

Application--especially in combination with the new camera--is so easy and advantageous that it has advanced to become the standard procedure in our practice. Potential for improvement still exists in the stiffness of the cannula, in a release mechanism located separately from the cannula and in the impudent demand to completely do away with powder and spray. Despite announcements to the contrary by alternative systems, the fulfilment of this desire appears to be a long way off. PMID:19213361

Reiss, B

2009-01-01

93

Preparation of superconductor precursor powders  

DOEpatents

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

Bhattacharya, Raghunath (Littleton, CO)

1998-01-01

94

Shock compaction of molybdenum nitride powder  

NASA Astrophysics Data System (ADS)

Molybdenum nitride has a potential application in multi layer capacitors. Since this material is not readily available in bulk form, molybdenum nitride powder, consisting of a mixture of the nitrides Mo2N and MoN has been compacted to 12 mm circular, 1-2 mm thick discs utilizing shock-compression technique. Powders were packed to 55-67 percent of the crystal density and shock compacted using a plate impact shock recovery system at 1.35 to 1.81 km/s impact velocity. The recovered compacts were characterized by scanning electron microscope, x-ray diffraction and cyclic voltammetry to evaluate its electrochemical stability in sulphuric acid. This paper presents the optimization technique used for compaction and the characteristics of the recovered compacts.

Roberson, S.; Davis, R. F.; Joshi, V. S.; Fienello, D.

1998-07-01

95

Fabricating sports equipment components via powder metallurgy  

Microsoft Academic Search

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

V. S. Moxson

2001-01-01

96

Pourability Enhancement of PETN Explosive Powders  

SciTech Connect

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

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

1987-01-01

97

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

98

Absorptance of powder materials suitable for laser sintering  

Microsoft Academic Search

The normal spectral absorptance of a number of metal, ceramic and polymer powders susceptible to be utilised for selective laser sintering (SLS) technique was experimentally determined. The measurements were performed with two laser wavelengths of 1.06?m and 10.6?m obtained by using two lasers – Nd-YAG and CO2 respectively. The change in the powder absorptance with time during laser processing was

Nikolay K. Tolochko; Yurii V. Khlopkov; Sergei E. Mozzharov; Michail B. Ignatiev; Tahar Laoui; Victor I. Titov

2000-01-01

99

Ultrafast Powder Diffraction  

NASA Astrophysics Data System (ADS)

An overview is given of the use of powder synchrotron-X-ray and neutron diffraction to study very fast physical or chemical processes that require time resolution of 500 ms or less. The experimental requirements to obtain data of good quality are considered, including the incident flux, detector characteristics, and the different strategies possible for irreversible and reversible processes. The latter are accessible via a stroboscopic approach whereas the former require the maximum rates of data acquisition. Some recent studies are described, drawn from the areas of combustion synthesis, metallurgy and catalysis. The exploitation of the bunch structure of a synchrotron ring to obtain time resolution in the sub-ns range with the pump-probe stroboscopic approach is also illustrated.

Fitch, Andy; Curfs, Caroline

100

Powdered resin for condensate polishing  

Microsoft Academic Search

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

Richard Hetherington

1997-01-01

101

Baking powder pica mimicking preeclampsia.  

PubMed

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

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

1992-07-01

102

Powder diffraction with spin polarized neutrons  

NASA Astrophysics Data System (ADS)

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

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

2010-05-01

103

Structural materials by powder HIP for fusion reactors  

NASA Astrophysics Data System (ADS)

Tokamak blankets have complex shapes and geometries with double curvature and embedded cooling channels. Usual manufacturing techniques such as forging, bending and welding generate very complex fabrication routes. Hot Isostatic Pressing (HIP) is a versatile and flexible fabrication technique that has a broad range of commercial applications. Powder HIP appears to be one of the most suitable techniques for the manufacturing of such complex shape components as fusion reactor modules. During the HIP cycle, consolidation of the powder is made and porosity in the material disappears. This involves a variation of 30% in volume of the component. These deformations are not isotropic due to temperature gradients in the part and the stiffness of the canister. This paper discusses the following points: (i) Availability of manufacturing process by powder HIP of 316LN stainless steel (ITER modules) and F82H martensitic steel (ITER Test Module and DEMO blanket) with properties equivalent to the forged one.(ii) Availability of powerful modelling techniques to simulate the densification of powder during the HIP cycle, and to control the deformation of components during consolidation by improving the canister design.(iii) Material data base needed for simulation of the HIP process, and the optimisation of canister geometry.(iv) Irradiation behaviour on powder HIP materials from preliminary results.

Dellis, C.; Le Marois, G.; van Osch, E. V.

1998-10-01

104

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

105

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

PubMed

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

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

2013-03-01

106

21 CFR 73.2645 - Aluminum powder.  

Code of Federal Regulations, 2012 CFR

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

2012-04-01

107

21 CFR 73.1645 - Aluminum powder.  

Code of Federal Regulations, 2012 CFR

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

2012-04-01

108

30 CFR 56.6901 - Black powder.  

...Resources 1 2014-07-01 2014-07-01 false Black powder. 56.6901 Section 56.6901 Mineral... Explosives General Requirements § 56.6901 Black powder. (a) Black powder shall be used for blasting only when a...

2014-07-01

109

Synthesis of Cu-CNT nanocomposite powder by ball milling.  

PubMed

In this paper, to improve the poor wettability between the Carbon nanotubes (CNTs) and metal matrix, the mechanical alloying (MA) technique by the ball milling method was employed. Also, the CNTs were pre-coated to improve the agglomeration of the CNTs with copper powder. The main aim of this work is the fabrication of Cu-CNT nanocomposite powder using the MA by ball milling. The as-received dendritic copper powders change their shape sequentially to flaky, disk-typed particles and finally, to globular type particles. Also, the tendency of globular formation was prominent in the milled Cu-Cu coated MWNTs (multi-walled carbon nanotubes) powder and the grain size of the sintered Cu coated MWNTs specimen decreased more than that of the pure copper specimen. Finally, the homogeneous Cu-CNT nanocomposite intermetallic particles having fine grains was produced by the MA method of ball milling. PMID:19908795

Kim, B J; Oh, S Y; Yun, H S; Ki, J H; Kim, C J; Baik, S; Lim, B S

2009-12-01

110

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

111

Preparation of superconductor precursor powders  

DOEpatents

A process for the preparation of a precursor metallic powder composition for use in the subsequent formation of a superconductor. The process comprises the steps of providing an electrodeposition bath comprising an electrolyte medium and a cathode substrate electrode, and providing to the bath one or more soluble salts of one or more respective metals which are capable of exhibiting superconductor properties upon subsequent appropriate treatment. The bath is continually energized to cause the metallic and/or reduced particles formed at the electrode to drop as a powder from the electrode into the bath, and this powder, which is a precursor powder for superconductor production, is recovered from the bath for subsequent treatment. The process permits direct inclusion of all metals in the preparation of the precursor powder, and yields an amorphous product mixed on an atomic scale to thereby impart inherent high reactivity. Superconductors which can be formed from the precursor powder include pellet and powder-in-tube products. 7 figs.

Bhattacharya, R.

1998-08-04

112

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

113

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

114

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

115

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

116

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

117

Pharmaceutical Powder Diffraction: Structure Solution from PXRD  

E-print Network

Pharmaceutical Powder Diffraction: Structure Solution from PXRD How reliable are our structures? Pharmaceutical Powder Diffraction: Structure Solution from PXRD How reliable are our structures? Maryjane

118

Silica powders for powder evacuated thermal insulating panel and method  

Microsoft Academic Search

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\\/cm³ and an external surface area in the range of about 90 to 600 m²\\/g is described. The silica powders are prepared by reacting a tetraalkyl silicate

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

1996-01-01

119

Silica powders for powder evacuated thermal insulating panel and method  

Microsoft Academic Search

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

Michael T. Harris; Osman A. Basaran; Thomas G. Kollie; Fred J. Weaver

1996-01-01

120

Silica powders for powder evacuated thermal insulating panel and method  

Microsoft Academic Search

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

Michael T. Harris; Osman A. Basaran; Thomas G. Kollie; Fred J. Weaver

1995-01-01

121

Silica powders for powder evacuated thermal insulating panel and method  

Microsoft Academic Search

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

Michael T. Harris; Osman A. Basaran; Thomas G. Kollie; Fred J. Weaver

1994-01-01

122

Combustion synthesis and effect of LaMnO 3 and LaOCl powder mixture on HMX thermal decomposition  

Microsoft Academic Search

LaOCl powder mixture and perovskite-type LaMnO3 were prepared by stearic acid gel combustion method. The obtained powders were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) and X-ray photoelectron spectroscopy (XPS) techniques. LaOCl powder mixture was a mixture of LaOCl and significant amounts of amorphous materials. When heated at 973.15K, the mixture was found

Zhi-Xian Wei; Yan Wang; Xue-Jun Zhang; Chang-Wen Hu

2010-01-01

123

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

124

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

125

Ceramic powder for sintering materials  

NASA Technical Reports Server (NTRS)

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

Akiya, H.; Saito, A.

1984-01-01

126

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

127

Neutron detectors comprising boron powder  

DOEpatents

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

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

2013-05-21

128

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

129

Effect of hydrolysis conditions on morphology and crystallization of nanosized TiO 2 powder  

Microsoft Academic Search

Nanosized titania powders were prepared by controlling the hydrolysis of TiCl4 in aqueous solution. The powders were characterised by TEM, HREM, XRD, ED, and BET techniques. In the presence of a small amount sulphate ions, when TiCl4 solution hydrolysed at 70°C, the obtained powder was pure anatase and its primary particle size was 3.5 nm, which is finer than that

Qinghong Zhang; Lian Gao; Jingkun Guo

2000-01-01

130

Ceramic oxide powders and the formation thereof  

DOEpatents

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

Katz, J.L.; Chenghung Hung.

1993-12-07

131

Ceramic oxide powders and the formation thereof  

DOEpatents

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

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

1993-01-01

132

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

133

Computing and Fitting SSNMR powder patterns with the Arithmetic-Geometric Mean and Edge Detection1  

Microsoft Academic Search

This paper presents a very ecient technique for approximating the ideal SSNMR powder pattern using the arithmetic-geometric mean and demonstrates finding an initial fitting of the ideal powder pattern to an experimental spectrum via Marr-Hildreth edge detection. In particular, the edge detection approach is used to identify possible values for the principal values of the chemical shielding tensor. These possibilities

J. K. Denny; M. B. Daniel; F. A. Kovacs

134

Deformation processing of metal powders: Part I—Cold isostatic pressing  

Microsoft Academic Search

The coupled thermomechanical problem of Hot lsostatic Pressing (HIPing) of metal powders during Stage I of the densification process is analyzed using analytical as well as numerical techniques. Densification of the powder is assumed to occur due to plastic yielding and creep of the metal particles as well as due to boundary and surface diffusion. The constitutive models developed by

R. M. GOVINDARAJAN; N. ARAVAS

1994-01-01

135

Properties of chemical vapor infiltration diamond deposited in a diamond powder matrix  

Microsoft Academic Search

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 have developed two techniques: electrophoretic deposition and screen printing, to form nonmined diamond powder precursors on substrates. They then densify these precursors

J. K. G. Panitz; D. R. Tallant; C. R. Hills; D. J. Staley

1993-01-01

136

An In Vitro Method of Evaluating Tolnaftate Release from Topical Powder  

Microsoft Academic Search

A dissolution apparatus was constructed to evaluate tolnaftate release from topical powders. It consisted of a mesh unit to support the powder, a receptor phase, and a sink. This report describes three parameters that were used to evaluate this technique. First, three different areas of contact were examined using 52-, 41-, or 30-µm mesh supports. Second, the effect of the

Tacey X. Viegas; Arthur H. Kibbe; Ahmed H. Hikal; Robert W. Cleary; Alan B. Jones

1986-01-01

137

Dynamic consolidation of rapidly solidified titanium alloy powders by explosives  

Microsoft Academic Search

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

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

1991-01-01

138

Synchrotron Mossbauer Spectroscopy of powder samples  

SciTech Connect

Synchrotron Mossbauer Spectroscopy, SMS, is an emerging technique that allows fast and accurate determination of hyperfine field parameters similar to conventional Mossbauer spectroscopy with radioactive sources. This new technique, however, is qualitatively different from Mossbauer spectroscopy in terms of equipment, methodology, and analysis to warrant a new name. In this paper, the authors report on isomer shift and quadrupole splitting measurements of Mohr`s salt, Fe(NH{sub 4}){sub 2}(SO{sub 4}){sub 2}{center_dot}6H{sub 2}O for demonstration purposes. Theoretical calculations were performed and compared to experiments both in energy and time domain to demonstrate the influence of thickness distribution and preferential alignment of powder samples. Such measurements may prove to be useful when the data collection times are reduced to few seconds in the third generation, undulator based synchrotron radiation sources.

Alp, E.E.; Sturhahn, W.; Toellner, T.

1994-08-01

139

Improvement of insulin absorption from intratracheally administrated dry powder prepared by supercritical carbon dioxide process.  

PubMed

The purpose of this study was to improve insulin absorption from dry powder after administration in lung without an absorption enhancer. The dry powders, with mannitol as a carrier, were prepared with or without an absorption enhancer (citric acid) by supercritical carbon dioxide (SCF) and spray drying (SD) processes. Insulin powder was precipitated from dimethyl sulfoxide and aqueous solutions by dispersing the insulin solutions from parallel and V-type nozzles, respectively, into supercritical carbon dioxide, which is an antisolvent for insulin. In vitro aerosol performance was evaluated with a cascade impactor. Insulin powder containing citric acid prepared by the SCF method (MIC SCF) showed improved inhalation performance compared with insulin powder prepared by the SD process, although the particle size of the former powder was larger than that in powders prepared by SD. Insulin absorption was estimated from the change in plasma glucose level. The blood glucose level after administration of the insulin powder without citric acid prepared by the SCF process (MI SCF) decreased rapidly, and a significant difference was observed for areas under the curve of change in plasma glucose concentration versus time (AUCs) between MI SCF and the insulin powder without citric acid prepared by the SD process (MI SD). These results suggest that the SCF technique would be useful to prepare dry powders suitable for inhalation. PMID:14603493

Todo, Hiroaki; Iida, Kotaro; Okamoto, Hirokazu; Danjo, Kazumi

2003-12-01

140

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

141

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

142

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

143

Metallurgical examination of powder metallurgy uranium alloy welds  

SciTech Connect

Inertia welding provided a successful technique for joining full density, powder metallurgy uranium-6 wt pct niobium alloy. Initial joining attempts concentrated on the electron beam method, but this method failed to produce a sound weld. The electron beam welds and the inertia welds were evaluated by radiography and metallography. Electron beam welds were attempted on powder metallurgy plates which contained various levels of oxygen and nitrogen. All welds were porous. Sixteen inertia welds were made and all welds were radiographically sound. The tensile properties of the joints were found to be equivalent to the p/m base metal properties.

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

1986-06-01

144

Minerals Arranged by X-Ray Powder Diffraction  

NSDL National Science Digital Library

This directory provides a listing of minerals arranged by Powder X-ray Diffraction (XRD) data . XRD is one of the primary techniques used to examine the physico-chemical make-up of unknown solids, in which a powdered sample is illuminated with X rays of a fixed wavelength and the intensity of the reflected radiation is recorded using a goniometer. Minerals are arranged in increasing order of D1 spacing, with D2 and D3 spacings also provided. Each mineral name is a link to additional information on the mineral.

145

Characterisation of Aronia powders obtained by different drying processes.  

PubMed

Nowadays, food industry is facing challenges connected with the preservation of the highest possible quality of fruit products obtained after processing. Attention has been drawn to Aronia fruits due to numerous health promoting properties of their products. However, processing of Aronia, like other berries, leads to difficulties that stem from the preparation process, as well as changes in the composition of bioactive compounds. Consequently, in this study, Aronia commercial juice was subjected to different drying techniques: spray drying, freeze drying and vacuum drying with the temperature range of 40-80 °C. All powders obtained had a high content of total polyphenols. Powders gained by spray drying had the highest values which corresponded to a high content of total flavonoids, total monomeric anthocyanins, cyaniding-3-glucoside and total proanthocyanidins. Analysis of the results exhibited a correlation between selected bioactive compounds and their antioxidant capacity. In conclusion, drying techniques have an impact on selected quality parameters, and different drying techniques cause changes in the content of bioactives analysed. Spray drying can be recommended for preservation of bioactives in Aronia products. Powder quality depends mainly on the process applied and parameters chosen. Therefore, Aronia powders production should be adapted to the requirements and design of the final product. PMID:23871034

Horszwald, Anna; Julien, Heritier; Andlauer, Wilfried

2013-12-01

146

Triboelectric charging of polymer powders in fluidization and transport processes  

Microsoft Academic Search

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

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

1997-01-01

147

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

148

Intradermal needle-free powdered drug injection  

E-print Network

This thesis presents a new method for needle-free powdered drug injection. The design, construction, and testing of a bench-top helium-powered device capable of delivering powder to controllable depths within the dermis ...

Liu, John (John Hsiao-Yung)

2012-01-01

149

THE NITRATION OF POWDERED URANIUM BY NITROGEN  

Microsoft Academic Search

The nitration of powdered uranium by nitrogen was studied by- ; thermograviimetry- between 300 and 700 deg C. The results obtained show the ; complexity of a powdered soidgas reaction and chiefly the effect of granulometry. ; (trauth);

C. Moreau; J. Philippot

1961-01-01

150

LAND USE AND OWNERSHIP, POWDER RIVER BASIN  

E-print Network

Chapter PM LAND USE AND OWNERSHIP, POWDER RIVER BASIN By T.T. Taber and S.A. Kinney In U........................................PM-1 Map Information for the Powder River Basin Land Use and Land Cover map...........................................................PM-2 Map Information for the Powder River Basin Subsurface Ownership map

151

30 CFR 57.6901 - Black powder.  

...Resources 1 2014-07-01 2014-07-01 false Black powder. 57.6901 Section 57.6901 Mineral...Requirements-Surface and Underground § 57.6901 Black powder. (a) Black powder shall be used for blasting only when a...

2014-07-01

152

Effect of IN718 Recycled Powder Reuse on Properties of Parts Manufactured by Means of Selective Laser Melting  

NASA Astrophysics Data System (ADS)

Powder quality control is essential to obtain parts with suitable mechanical properties in Selective Laser Melting manufacturing technique. One of the most important advantages of suchtechnique is that it allows an efficient use of the material, due to the possibility to recycle and reuse un-melted powder. Nevertheless, powder material properties may change due to repeated recycling, affecting this way the mechanicalbehavior of parts. In this paper the effect of powder reuse on its quality and on the mechanical properties of the resulting melted parts is studied via self-developed recycling methodology. The material considered for investigation was IN718, a nickel superalloy widely used in industry. After recycling powder up to 14 times, no significant changes were observed in powder and test parts properties. The results obtained in this work will help to validate powder recycling methodology for its use in current industrial Selective Laser Melting manufacturing.

Ardila, L. C.; Garciandia, F.; González-Díaz, J. B.; Álvarez, P.; Echeverria, A.; Petite, M. M.; Deffley, R.; Ochoa, J.

153

Preparation and characterization of Y 3Al 5O 12:Ce and Y 2O 3:Eu phosphors powders by combustion process  

Microsoft Academic Search

A novel ceramic synthesis technique, combustion process was investigated for the production of phosphor powders. In this study, we have developed a new method to product phosphor powders, and applied this process into two materials fabrication. Y3Al5O12:Ce and Y2O3:Eu phosphor powders were successfully synthesized by combustion process. The process takes only 15min to obtain Y3Al5O12:Ce and Y2O3:Eu phosphor powders. The

Yen-Pei Fu; Shaw-Bing Wen; Chin-Shang Hsu

2008-01-01

154

[Impact of directly compressed auxiliary materials on powder property of fermented cordyceps powder].  

PubMed

To investigate such physical indexes as hygroscopicity, angle of repose, bulk density, fillibility of compression of mixed powder of directly compressed auxiliary materials and fermented cordyceps powder by using micromeritic study methods. The results showed that spray-dried lactose Flowlac100 and microcrystalline cellulose Avicel PH102 had better effect in liquidity and compressibility on fermented cordyceps powder than pregelatinized starch. The study on the impact of directly compressed auxiliary materials on the powder property of fermented cordyceps powder had guiding significant to the research of fermented cordyceps powder tablets, and could provide basis for the development of fermented cordyceps powder tablets. PMID:24754170

Chen, Li-Hua; Yue, Guo-Chao; Guan, Yong-Mei; Yang, Ming; Zhu, Wei-Feng

2014-01-01

155

Composition of reactive powder concretes  

Microsoft Academic Search

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

Pierre Richard; Marcel Cheyrezy

1995-01-01

156

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 ? cm2 at 800 °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 mW cm-2 at 800 °C.

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

2014-02-01

157

Metallic/cermet laminates from explosively consolidated powders  

SciTech Connect

The technique this study focuses on is the use of explosive consolidation to create distinct interfacial systems from metallic and metallic-cermet powder mixtures. One of the advantages of this technique is that undesired intermetallic formation between the constituents (which can happen with other techniques such as hot-pressing) is usually avoided due to the relatively low temperatures involved. In addition, interfacial strengths actually higher than the surrounding bulk material are achieved. Finally, since extremely high dislocation densities are created by the passage of the shock wave, the strength contribution from dislocation pile-ups is maximized.

Thomas, H.; Inal, O.T.

1999-05-21

158

Powder Coatings Technology Update. Final report  

SciTech Connect

The objective of this report is to provide an overview of the current status of powder-coating technology. Because powder coatings are applied as dry, finely divided particles, there are no volatile organic compounds (VOC's) released during application, and only minute quantities are released during the curing process. Therefore, the increased use of powder coatings, as an alternative to liquid solvent-based coatings, represents a significant reduction in emissions of VOC's. The report describes current powder-coating materials and equipment, end uses, and economic advantages of the use of powder coatings. Included in the report are discussions of the disadvantages and potential problems identified early in the powder-coating-development process. The report addresses the resolutions of many of these problems. The report is intended to be of use to State and local agencies in their evaluation of powder coatings as an alternative to coatings containing VOC's.

Hester, C.I.; Nicholson, R.L.; Cassidy, M.A.

1989-09-01

159

The enhancement of the properties of WC-Co HVOF coatings through the use of nanostructured and microstructured feedstock powders  

Microsoft Academic Search

Three coatings have been obtained using nanostructured, bimodal and conventional WC-Co cermet powders by means of High Velocity Oxygen-Fuel (HVOF) technique. Propylene has been used as fuel gas. All the powders have been sprayed under the same spraying parameters. These powders and the coatings obtained have been characterized using XRD and SEM.The friction wear resistance of the coatings has been

J. M. Guilemany; S. Dosta; J. R. Miguel

2006-01-01

160

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

SciTech Connect

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

Alhambra, E.M.

1994-09-01

161

Powder processing and abrasion resistance of in-situ iron matrix-TiC-reinforced composites  

SciTech Connect

Reactive powder processing techniques were used to produce TiC reinforced ferrous matrix composites. Mixture of elemental Fe, Cr, Ti and graphite powders were hot-pressed to full density. During heating a Self-propagating High-temperature Synthesis (SHS)-type reaction initiated at about 1150°C and transformed the Ti, Cr and graphite powders to TiC and (Fe,Cr)x,Cy in an steel (Fe-Cr-C) matrix. This reaction occurred only in those mixtures containing Ti powder (i.e., no such reaction was detected in mixtures of Fe, Cr and graphite powders). The resultant hot-pressed microstructures consisted of uniformly dispersed and large carbide particles in a steel matrix, and ideal microstructure for abrasion resistance. The abrasion resistance of the composites were evaluated by pin-abrasion testing and the results compared favorable to traditional wear resistant materials, such as cast iron.

Dogan, Omer N.; Alman, David E.; Hawk, Jeffrey A.

2000-10-01

162

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

163

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

164

Selective laser melting W–10 wt.% Cu composite powders  

Microsoft Academic Search

Tungsten–Copper (W–Cu) alloys are promising materials for electrical and thermal applications. However, its forming method\\u000a still remains limited in conventional powder metallurgy technique which is not suitable for manufacturing parts with intricate\\u000a shapes. In this work, selective laser melting technology was introduced for fabricating W–10 wt.% Cu alloys parts. The morphological\\u000a feature of a single molten track was analyzed. The results

Ruidi Li; Yusheng Shi; Jinhui Liu; Zhan Xie; Zhigang Wang

2010-01-01

165

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

SciTech Connect

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

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

2000-04-24

166

New technology for separating resin powder and fiberglass powder from fiberglass-resin powder of waste printed circuit boards.  

PubMed

New recycling technologies have been developed lately to enhance the value of the fiberglass powder-resin powder fraction (FRP) from waste printed circuit boards. The definite aim of the present paper is to present some novel methods that use the image forces for the separation of the resin powder and fiberglass powder generated from FRP during the corona electrostatic separating process. The particle shape charactization and particle trajectory simulation were performed on samples of mixed non-metallic particles. The simulation results pointed out that particles of resin powder and particles of fiberglass powder had different detach trajectories at the conditions of the same size and certain device parameters. An experiment carried out using a corona electrostatic separator validated the possibility of sorting these particles based on the differences in their shape characteristics. The differences in the physical properties of the different types of particles provided the technical basis for the development of electrostatic separation technologies for the recycling industry. PMID:24678800

Li, Jia; Gao, Bei; Xu, Zhenming

2014-05-01

167

Welding of a powder metallurgy uranium alloy  

SciTech Connect

The interest at the Oak Ridge Y-12 Plant in powder metallurgy (P/M) uranium parts is due to the potential cost savings in the fabrication of the material, to achieving a more homogeneous product, and to the reduction of uranium scrap. The joining of P/M uranium-6 wt-% niobium (U-6Nb) alloys by the electron beam (EB) welding process results in weld porosity. Varying the EB welding parameters did not eliminate the porosity. Reducing the oxygen and nitrogen content in this P/M uranium material did minimize the weld porosity, but this step made the techniques of producing the material more difficult. Therefore, joining wrought and P/M U-6Nb rods with the inertia welding technique is considered. Since no gases will be evolved with the solid-state welding process and the weld area will be compacted, porosity should not be a problem in the inertia welding of uranium alloys. The welds that are evaluated are wrought-to-wrought, wrought-to-P/M, and P/M-to-P/M U-6Nb samples.

Holbert, R.K.; Doughty, M.W.; Alexander-Morrison, G.M. (Fairchild Space Co., Germantown, MD (USA))

1989-05-01

168

Thixoforming of Stellite Powder Compacts  

NASA Astrophysics Data System (ADS)

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

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

2007-04-01

169

Characterization of tribocharging properties of powder paint  

Microsoft Academic Search

The charge-to-mass ratio (q\\/m) of individual particles plays a vital role in the powder coating process. Simultaneous measurements of particle size and electrostatic charge were performed on triboelectrically charged powder paint and other powders in the particle size range 1.0 to 65.0 ?m in diameter. An electrical single particle aerodynamic relaxation time (ESPART) analyzer was used to measure electrostatic charge

M. K. Mazumder; S. Banerjee; R. E. Ware; C. Mu; N. Kaya; C. C. Huang

1994-01-01

170

Characterization of tribocharging properties of powder paint  

Microsoft Academic Search

Simultaneous measurements of particle size and electrostatic charge was performed on charged powder paint and other powders in the particle size range from 1.0 to 65.0 ?m in diameter. An electrical single-particle aerodynamic relaxation time analyzer was used to measure electrostatic charge and aerodynamic size distributions on a single particle basis and in a noninvasive manner. The powders were triboelectrically

M. K. Mazumder; S. Banerjee; R. E. Ware; N. Kaya; C. C. Huang

1992-01-01

171

Selective laser sintering of amorphous metal powder  

Microsoft Academic Search

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

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

2005-01-01

172

Determination of copper in milk powder by electrothermal atomic absorption and atomic emission spectrometry  

Microsoft Academic Search

Summary Electrothermal atomic absorption spectrometry (ETA-AAS) and atomic emission spectrometry (ETA-AES) have been applied to the determination of copper in powdered milk. A homogeneous dispersion procedure for the preparation of the milk powder is described which was found to be simple, rapid and less susceptible to contamination than dry ashing or wet digestion methods. Both ETA-AAS and ETA-AES techniques were

Z. A. Khammas; J. Marshall; D. Littlejohn; J. M. Ottaway; S. C. Stephen

1985-01-01

173

Superconducting and microstructural properties of shock-compacted highT sub c oxide powders  

Microsoft Academic Search

Shock compacted specimens of YBa2Cu3O(7-delta) and HoBa2Cu3O(7-delta) high-T(sub c) oxide powder mixed with 30 percent (vol) Ag powder were prepared using the LLNL two-stage light-gas gun in the 30 to 200 kbar range. We report the experimental technique and results of an investigation of the microstructural and superconducting properties of these composite specimens. Measurements of magnetic susceptibility show that bulk

C. L. Seaman; E. A. Early; M. B. Maple; W. J. Nellis; J. B. Holt; M. Kamegai; G. S. Smith

1989-01-01

174

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

Microsoft Academic Search

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

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

1995-01-01

175

Preparation, characterization and photocatalytic properties of ZnTiO 3 powders  

Microsoft Academic Search

A novel photocatalyst ZnTiO3 powder was prepared by a modified alcoholysis method, using ethylene glycol as reagent\\/solvent and acetylacetone as stabilizer. A series of analytical techniques were used to characterize the crystallinity, composition, bandgap, morphology, specific surface area and grain size of ZnTiO3 powders. The relationship between the physicochemical property and the photocatalytic activity was deeply investigated, too. It is

Ji-Zhou Kong; Ai-Dong Li; Hai-Fa Zhai; Hui Li; Qing-Yu Yan; Jan Ma; Di Wu

2009-01-01

176

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

Microsoft Academic Search

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

R. K. Dube

1991-01-01

177

Thermoplastic dry polymer powder prepregging  

SciTech Connect

Thermoplastic resin systems have shown potential for reducing the manufacturing costs and improving the damage tolerance of composite structures. Current methods for thermoplastic resin impregnation of fiber bundles are limited by various difficulties and thus produce poor quality prepregs. The emerging technology of fiber is one of the most promising options, producing excellent matrix drape, and feasibility for a wide variety of matrix systems. An electrostatic dry polymer powder prepregging system was developed at the NSF Science and Technology Center at Virginia Tech, and has been used to produce high quality thermoplastic towpreg from a wide variety o polymer matrices. Additionally, a modification of the system allows for the production of towpreg from 15 gram polymer samples. This is ideal for the production of composites from resin systems under development, allowing early feedback concerning processing and composite mechanical performance.

Bucher, R.A.; Loos, A.C.; Meyer, G. [Virginia Polytechnic Institute and State Univ., Blacksburg, VA (United States)] [and others

1995-12-01

178

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

Microsoft Academic Search

Dry Powder Inhalers have drawn great attention from pharmaceutical scientists in recent years in particular those consisting of low-dose micronized drug particles associated with larger carrier particles and called interactive mixtures. However, there is little understanding of the relation between bulk powder properties such as powder structure and its aerodynamic dispersion performance. The aim of this work was to develop

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

2010-01-01

179

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

Microsoft Academic Search

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

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

2005-01-01

180

Non-invasive detection of powders concealed within diffusely scattering plastic containers  

Microsoft Academic Search

We demonstrate the potential of Spatially Offset Raman Spectroscopy (SORS) for the non-invasive detection of chemicals in powder form (e.g. illicit drugs or explosives) concealed within diffusely scattering containers. The performance of the technique is compared with that of conventional backscattering Raman spectroscopy. Enhanced sensitivity is achieved by the SORS technique's inherent ability to effectively suppress fluorescence and Raman contributions

C. Eliasson; N. A. Macleod; P. Matousek

2008-01-01

181

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.

182

A General Powder X-Ray Photography  

Microsoft Academic Search

AT the outset of calculation, no assumption whatever is made as to the symmetry and dimensions of the unit cell. The powder photograph is simply treated as that of a triclinic crystal without special relationship between its constants. The reflexion hkl in the powder photograph, then, may be expressed in terms of its reciprocal lattice1, thus: where theta is the

T. Ito

1949-01-01

183

April 11, 2013 Powder Consolidation under Pressure  

E-print Network

Science and Technology. 2011;25:483-499 4. Alderborn G, Nystrom C. Pharmaceutical Powder Compaction generally formed by compression, is the most common pharmaceutical solid dosage form because of its economic Technology. 1996 5. Antikainen O, Yliruusi J. Determining the compression behavior of pharmaceutical powders

Thomas, David D.

184

Reaction Kinetics of Powdered Uranium and Deuteroammonia  

Microsoft Academic Search

A rate law for the nitridation of pyrophoric uranium with deuteroammonia was established for the entire course of the reaction. The rate of reaction between powdered uranium and deuteroammonia was determined to be a linear function of the initial Brunauer, Emmett, and Teller (BET) surface area and the fraction of unreacted uranium. Sintering of powdered uranium to a stable surface

R. M. Alire; J. H. McCrary

1966-01-01

185

Dense silica coatings on ceramic powder particles  

SciTech Connect

Dense silica coatings on the surface of inorganic powders particles are prepared by the hydrolysis of tetraethoxysilane (TEOS) in alcoholic suspensions. In a first reaction step, the TEOS is pre-hydrolysed in acidic solution and afterwards, a suspension of powder particles in this reaction solution is treated with ammonia which results in a dense silica coating of typically 10 - 100 nm thickness. Different luminescent powders which are used in the manufacture of cathode-ray tubes or fluorescent lamps have been coated by this procedure. The silica coating forms a transparent layer and the suspension properties of the coated powders are determined by the silica layer. The silica coating also protects sulfidic luminescent powders from being attacked by oxidizing agents like dichromate ions which are used in the suspension formulations for TV tube fabrication.

Opitz, J.F.A.; Mayr, W. [Philips GmbH Forschungslaboratorien, Aachen (Germany)

1995-09-01

186

Discrete element modeling of powder consolidation and the formation of titanium-matrix composites from powder-fiber monotapes  

NASA Astrophysics Data System (ADS)

A three year research effort is completed with the development of the Discrete Element Consolidation Analyzer (DECA) for process modeling the formation of titanium composites from powder-fiber monotapes. The primary goal of the DECA process model is to provide a statistically realistic analysis of the various physical processes necessary to achieve higher quality composites from the powder-fiber technique. Over the course of this effort, research and code development was conducted in three distinct stages. The first stage focused on the simulation of initial geometry of the powder and fibers as well as the evolution of tape configuration during the pre-consolidation processing steps. The second stage developed the mechanics of the discrete element powder consolidation and the material characterization methods necessary to model the viscoplastic response of the powder to transient thermal and mechanical boundary conditions. The final stage incorporated the presence of fibers to evaluate the interaction mechanics and possible fibers damage resulting from discrete powder-fiber contacts. As a conclusion to the research, DECA model predictions of density versus time for various consolidation profiles are directly compared to actual consolidation test results and a DECA prescribed process profile is used to fabricate a 6sp{''} × 6sp{''} composite panel of Ti-6242/SCS-6. In completing this research, the discrete element modeling technique has proven to be a powerful tool for the analysis and simulation of metal powder consolidation as well as the consolidation of metal matrix composites. The DECA code orchestrates the use of particle kinetics, some simple aspects of gas dynamics, elasticity, plasticity, creep and various innovative material characterization methods to produce a seamless analysis for powder metallurgy processing of composites. Through the application of the DECA capability, many aspects of the processing stages have been elucidated for further investigation and possibly for optimization to in the end provide the underlying goal of increasing quality and reduce cost of producing composites from the powder-fiber monotape method. As a minimum, it was desired that the resulting code provide an accurate prediction of relative density as a function of applied pressure, temperature, and time. This goal was achieved. However, it was later realized that under specific conditions of pre-heat and unidirectional compaction, the rate change in relative density could be determined by the rate of applied load. With the appropriate control and load capacity, densification by plasticity and transient creep mechanisms can achieve complete void removal. Unfortunately, the real world doesn't work with 1sp{''} × 1sp{''} samples and the pressurization rates attained by most HIP units are several orders of magnitude below those specific conditions in which it is possible to essentially "hammer" the voids out of the composite. As a result, it was learned that under certain conditions Ti-6242/SCS-6 monotape (temperature between 1650sp°F and beta-transus with a loading rate greater than 10 kips/min.), it is possible to consolidate Ti-6242/SCS-6 monotape composite in a matter of minutes without damaging fibers. (Abstract shortened by UMI.)

Newell, Kenneth James

187

Nano-scale analysis of titanium dioxide fingerprint-development powders  

NASA Astrophysics Data System (ADS)

Titanium dioxide based powders are regularly used in the development of latent fingerprints on dark surfaces. For analysis of prints on adhesive tapes, the titanium dioxide is suspended in a surfactant and used in the form of a small particle reagent (SPR). Analysis of commercially available products shows varying levels of effectiveness of print development, with some powders adhering to the background as well as the print. Scanning electron microscopy (SEM) images of prints developed with different powders show a range of levels of aggregation of particles. Analytical transmission electron microscopy (TEM) of the fingerprint powder shows TiO2 particles with a surrounding coating, tens of nanometres thick, consisting of Al and Si rich material. X ray photoelectron spectroscopy (XPS) is used to determine the composition and chemical state of the surface of the powders; with a penetration depth of approximately 10nm, this technique demonstrates differing Ti: Al: Si ratios and oxidation states between the surfaces of different powders. Levels of titanium detected with this technique demonstrate variation in the integrity of the surface coating. The thickness, integrity and composition of the Al/Si-based coating is related to the level of aggregation of TiO2 particles and efficacy of print development.

Reynolds, A. J.; Jones, B. J.; Sears, V.; Bowman, V.

2008-08-01

188

Investigation of NIR hyperspectral imaging for discriminating melamine in milk powder  

NASA Astrophysics Data System (ADS)

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

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

2013-05-01

189

Instability of bacteriophages in spray-dried trehalose powders is caused by crystallization of the matrix.  

PubMed

Spray drying is a valuable technique in pharmaceutical dosage formulation, capable of producing amorphous, spherical powders, suitable for pulmonary deposition and further downstream processing. In this study, we show that spray drying bacteriophages together with trehalose results in an amorphous powder matrix with high glass transition temperature (between 116 and 118°C), typical for amorphous trehalose. These powders are stable at low temperatures (4°C) and relative humidity (0%). However, high humidity causes crystallization of the amorphous matrix, destroying the embedded phages. Furthermore, storage at higher temperature (25°C) causes thermal instability of the embedded phages. The results show that storage conditions are important parameters to take into account in phage therapy development. The resulting particles are hollow spheres, with suitable aerodynamic diameters for deposition into the deep lungs. This opens possibilities to use these phage-containing powder formulations to tackle pulmonary infectious diseases, especially caused by antibiotic resistant pathogens. PMID:24950368

Vandenheuvel, Dieter; Meeus, Joke; Lavigne, Rob; Van den Mooter, Guy

2014-09-10

190

Fabrication and Characterization of Cu2ZnSnS4 Powders by a Hydrothermal Method  

NASA Astrophysics Data System (ADS)

In this study, Cu2ZnSnS4 (CZTS) powders are successfully synthesized by a simple hydrothermal method, and the concentration of thiourea, reaction time, reaction temperature, and precursor concentration ratio (Zn/Sn) are all examined in order to obtain the optimal conditions for this process. In addition, the characteristics of the resulting powder are examined using the X-ray powder diffraction (XRD), scanning electron microscope (SEM), energy dispersive spectrometer (EDS), Raman, transmission electron microscope (TEM) and ultraviolet-visible (UV-vis) techniques. The results indicate that the concentration of sulfur ions is 6 times of that of the copper ions, and that the production process required a reaction time of 72 h and a reaction temperature of 180 °C, and the energy gap of the CZTS powder is approximately 1.45 eV.

Hsu, Kuo-Chin; Liao, Jiunn-Der; Chao, Li-Min; Fu, Yaw-Shyan

2013-06-01

191

Dynamic fragmentation of powders in spherical geometry  

NASA Astrophysics Data System (ADS)

Experimental evidence from a wide range of sources shows that the expanding cloud of explosively disseminated material comprises of "particles" or fragments which have different dimensions from those associated with the original material. Photographic evidence shows jets or fingers behind these expanding fragments. Powders and liquids have often been used to surround explosives to act as blast mitigants; this is the main driver for our research. Other examples of areas where these features are observed include fuel air explosives and enhanced blast explosives as well as quasi-static pressure mitigation systems. In this paper, we consider the processes occurring when an explosive interacts with a surrounding layer of powder in spherical geometry. Results from explosive experiments designed to investigate the effects of powder grain size and powder fill-to-burster charge mass ratio (/) are presented and compared with results from numerical modelling to explore what determines the primary fragment size distribution resulting from explosive dissemination of a layer of material and when this process begins. The evidence clearly shows that the process starts during the first wave transit period of the powder material and, despite the surrounding material initially being a loose powder, shows the characteristics of a brittle fracture mechanism. Later time video evidence shows the same number of jets or fingers as are identified by X-rays of the early, primary fragmentation process. The number of fragments is only a very weak function of the initial grain size of the powder.

Milne, A. M.; Floyd, E.; Longbottom, A. W.; Taylor, P.

2014-09-01

192

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 (0.3–37.9% and 0.1–31.8% of the predispersed test powders, respectively). For many powders, a significant respirable dustiness was observed. For most powders studied, the respirable dustiness accounted for approximately one-third of the total dustiness. It is believed that this relationship holds for many fine and nanoscale test powders (i.e. those primarily selected for this study), but may not hold for coarse powders. Neither total nor respirable dustiness was found to be correlated with BET surface area, therefore dustiness is not determined by primary particle size. For a subset of test powders, aerodynamic particle size distributions by number were measured (with an electrical low-pressure impactor and an aerodynamic particle sizer). Particle size modes ranged from approximately 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

193

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

194

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

195

Glass powder blended cement hydration modelling  

NASA Astrophysics Data System (ADS)

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

Saeed, Huda

196

Electrosintering of iron powder compacts  

NASA Astrophysics Data System (ADS)

The influence of a nominal external electric fieldE=3 to 10 kV/cm on the sintering of iron powder compacts for 30 minutes at 1140°C in a vacuum of ˜10-6 torr was investigated. It was found that the field reduced the porosity by as much as 29 to 73 pct compared to sintering without a field, the magnitude depending on the procedure employed to measure the density of the specimen. Optical microscopy revealed that the specimen electrosintered withE=10 kV/cm had a skin of ˜0.2 mm in thickness, where the porosity was significantly less than in the interior. This was also the depth of carburization that was obtained upon carburizing the electrosintered specimens. It is proposed that the decrease in porosity produced by the field results from a decrease in the chemical potential of vacancies at or just below the charged external surface. Vacancy flux equations employed to calculate the porosity as a function of distance below the external surface showed that the porosity becomes approximately zero at a distance ofx c=0.4 to 0.5 mm below the surface, which is in reasonable accord with the microscopy measurements. Similar values ofx c were obtained by assuming that the entire porosity decrease given by the density measurements occurred in a ring of thickness ofx c below the external surface. The difference in the density measured by two Archimedes-principle procedures and microscopy observations suggests that the cavities open to the external surface of the electrosintered specimens are smaller or narrower than those for specimens sintered without a field.

Fahmy, Yusef; Conrad, Hans

2001-03-01

197

Complex microwave conductivity of Na-DNA powders  

E-print Network

We report the complex microwave conductivity, $\\sigma=\\sigma_1-i\\sigma_2$, of Na-DNA powders, which was measured from 80 K to 300 K by using a microwave cavity perturbation technique. We found that the magnitude of $\\sigma_1$ near room temperature was much larger than the contribution of the surrounding water molecules, and that the decrease of $\\sigma_1$ with decreasing temperature was sufficiently stronger than that of the conduction of counterions. These results clearly suggest that the electrical conduction of Na-DNA is intrinsically semiconductive.

H. Kitano; K. Ota; A. Maeda

2006-08-01

198

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

199

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

200

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

201

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

202

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

203

Hot Isostatic Pressing of Ceramic Powder Compacts.  

National Technical Information Service (NTIS)

The effect of temperature, pressure and time on the rate of densification of submicron alumina powder during hot isostatic pressing has been determined using a dilatometer to continuously monitor volumetric changes. A Fortran computer program is used to m...

J. K. McCoy, R. R. Wills

1984-01-01

204

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

205

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

206

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

207

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

208

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

209

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

210

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

211

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

212

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

Moorhead, A.J.; Kim, H.

1999-08-10

213

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

214

Energy approach to considering multicomponent powder systems  

NASA Astrophysics Data System (ADS)

The problems of formation of the structure of a dispersed multicomponent powder mixture in mixing are considered from an energy standpoint. The homogeneous state of a powder mixture is shown to be energetically more favorable than the state of its separation, since it has a lower free energy margin and a higher configurational entropy. Depending on external conditions, a mixture of homogeneous regions with different component concentrations can have a more stable state.

Minaev, A. M.; Mordasov, D. M.; Tyalina, L. N.

2013-11-01

215

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

216

Advanced powder metallurgy aluminum alloys and composites  

NASA Technical Reports Server (NTRS)

The differences between powder and ingot metallurgy processing of aluminum alloys are outlined. The potential payoff in the use of advanced powder metallurgy (PM) aluminum alloys in future transport aircraft is indicated. The national program to bring this technology to commercial fruition and the NASA Langley Research Center role in this program are briefly outlined. Some initial results of research in 2000-series PM alloys and composites that highlight the property improvements possible are given.

Lisagor, W. B.; Stein, B. A.

1982-01-01

217

Moisture sorption of Thai red curry powder  

Microsoft Academic Search

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

Sudathip Inchuen; Woatthichai Narkrugsa; Pimpen Pornchaloempong

218

Fuel powder production from ductile uranium alloys.  

SciTech Connect

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

Clark, C. R.

1998-10-23

219

Ti Multicomponent Alloy Bulks by Powder Metallurgy  

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

220

The basics of powder lubrication in high-temperature powder-lubricated dampers  

SciTech Connect

The objective of this investigation is to develop a novel powder-lubricated rotor bearing system damper concept for use in high-temperature, high-speed rotating machinery such as advanced aircraft gas turbine engines. The approach discussed herein consists of replacing a conventional oil lubrication or frictional damper system with a powder lubrication system that uses the process particulates or externally fed powder lubricant. Unlike previous work in this field, this approach is based on the postulate of the quasi-hydrodynamic nature of powder lubrication. This postulate is deduced from past observation and present verification that there are a number of basic features of powder flow in narrow interfaces that have the characteristic behavior of fluid film lubrication. In addition to corroborating the basic mechanism of powder lubrication, the conceptual and experimental work performed in this program provides guidelines for selection of the proper geometries, materials, and powders suitable for this tribological process. The present investigation describes the fundamentals of quasi-hydrodynamic powder lubrication and defines the rationale underlying the design of the test facility. The performance and the results of the experimental program present conclusions reached regarding design requirements as well as the formulation of a proper model of quasi-hydrodynamic powder lubrication.

Heshmat, H.; Walton, J.F. (Mechanical Technology Inc., Latham, NY (United States))

1993-04-01

221

Optimizing Powder Distribution in Production of Surface Nano-Composite via Friction Stir Processing  

NASA Astrophysics Data System (ADS)

Notwithstanding the extensive interest in using friction stir processing (FSP) for producing metal matrix composite (MMC), more uniform powder distribution along the composite zone is still needed. In most studies, one groove is machined out of the specimen, filled with powder, and then processed by identical passes. In this investigation, an innovative technique was used that involved machining out of three gradient grooves with increasing depth from the advancing side to the retreating side instead of using a conventional sample with just a groove. Macro, optical, and scanning electron microscopy (SEM) images and microhardness test were used to evaluate the powder distribution. The images indicated that the most uniform distribution of SiC particles in the whole composite zone was related to a three-gradient grooves sample. Microohardness measurement of a three-gradient grooves sample, carried out along the cross section and perpendicular to the traverse direction of FSP, experiences less fluctuation in hardness compared with other techniques.

Heydarian, Arash; Dehghani, Kamran; Slamkish, Taymor

2014-06-01

222

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

NASA Astrophysics Data System (ADS)

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

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

2013-05-01

223

Lactose\\/?-Lactoglobulin Interaction During Storage of Model Whey Powders  

Microsoft Academic Search

The objective of this study was to evaluate the pres- ence or absence of interaction between lactose and ?- lactoglobulin during storage of model whey powders at different water activities (aw). Model whey powders were prepared by colyophilization of lactose with in- creasing quantities of ?-lactoglobulin. These colyophi- lized ?-lactoglobulin:lactose powders, assigned as BL powders, were stored from 0.11 to

M. E. C. Thomas; J. Scher; S. Desobry

2004-01-01

224

Dispersion of alkoxide-hydrolysed zirconia powders in aqueous suspensions  

Microsoft Academic Search

It is always desirable to control the agglomeration of ceramic powders in ceramic processing, as this strongly affects the sintering behaviour [1, 2] of the powders. A recent wet chemical process deserves attention because of the possibility of achieving ultrafine, high-purity monodispersed ceramic powders [3, 4] and the possibility of the powders obtained to yield ultrastructure [5]. During wet chemical

Kwang-Lung Lin; Huey-Chang Wang

1989-01-01

225

Tungsten Powder as an accelerator target & InBeam Testing  

E-print Network

: tungsten powder jet High speed image: tungsten powder flow in a pipe Dense-phase delivery Lean-phase lift - Reliability in harsh environment? - High static stress levels require much larger beam sigma than baseline) ­ Containment / erosion ­ Heat transfer and cooling of powder Unstable tungsten powder jet High speed image

McDonald, Kirk

226

Frontal Dynamics of Powder Snow Avalanches  

NASA Astrophysics Data System (ADS)

We model the dynamics of the head of dilute powder snow avalanches sustained by a massive frontal blow-out, arising as a weakly cohesive snow cover is fluidized by the very pore pressure gradients that the avalanche induces within the snow pack. Such material eruption just behind the front acts as a source of denser fluid thrust into a uniform ambient air flow at high Reynolds number. In such "eruption current", fluidization depth is inversely proportional to a bulk Richardson number representing avalanche height. By excluding situations in which the snow cover is not fluidized up to its free surface, we derive a criterion combining snow pack friction and density indicating which avalanches can produce a sustainable powder cloud. A mass balance involving snow cover and powder cloud sets avalanche height and mean density. By determining which solution of the mass balance is stable, we find that avalanches reach constant growth and acceleration rates for fixed slope and avalanche width. Under these conditions, we calculate the fraction of the fluidized cover that is actually scoured and blown-out into the cloud, and deduce from a momentum balance on the head that the avalanche accelerates at a rate only 14% of the gravitational component along the flow. We also calculate how far a powder cloud travels until its mean density becomes constant. Finally, we show that the dynamics of powder snow avalanches are crucially affected by the rate of change of their width, for example by reaching an apparent steady speed as their channel widens. If such widening is rapid, or if slope inclination vanishes, we calculate where and how powder clouds collapse. Predictions agree well with observations of powder snow avalanches carried out at the Vallee de la Sionne (Switzerland).

Louge, M. Y.; Carroll, C. S.; Turnbull, B.

2012-04-01

227

GRADIENT INDEX SPHERES BY THE SEQUENTIAL ACCRETION OF GLASS POWDERS  

SciTech Connect

The Department of Energy is seeking a method for fabricating mm-scale spheres having a refractive index that varies smoothly and continuously from the center to its surface [1]. The fabrication procedure must allow the creation of a range of index profiles. The spheres are to be optically transparent and have a refractive index differential greater than 0.2. The sphere materials can be either organic or inorganic and the fabrication technique must be capable of scaling to low cost production. Mo-Sci Corporation proposed to develop optical quality gradient refractive index (GRIN) glass spheres of millimeter scale (1 to 2 mm diameter) by the sequential accretion and consolidation of glass powders. Other techniques were also tested to make GRIN spheres as the powder-accretion method produced non-concentric layers and poor optical quality glass spheres. Potential ways to make the GRIN spheres were (1) by "coating" glass spheres (1 to 2 mm diameter) with molten glass in a two step process; and (2) by coating glass spheres with polymer layers.

MARIANO VELEZ

2008-06-15

228

Production and modification of hollow powders in plasma under controlled pressure  

NASA Astrophysics Data System (ADS)

Conducting plasma processes under high or low pressure is an efficient way to affect the heat, mass and momentum exchange in a two-phase flow and this technique is widely used in such well-developed technologies as low-pressure plasma spraying (LPPS) and high pressure plasma-chemical processes. In addition operating pressure is a key parameter in novel plasma process for modification of hollow powders properties. Plasma processing of porous ceramic powders is an effective method of producing hollow spheres (HOSP) with predefined properties. Regardless the method hollow powders were produced their geometric and structural properties can be adjusted by re-melting in plasma of certain pressure: low pressure processing will expand hollow spheres and high pressure - contract it. Regulating the outer diameter of hollow sphere allows adjusting its shell thickness, apparent density, gas pressure in the cavity etc. Preliminary experiments with zirconia hollow powders demonstrated good agreement with theoretical estimations of HOSP properties. The same technique can be used for adjusting properties of ceramic hollow powders produced by different methods, including cost effective fly-ash particles (cenospheres).

Gulyaev, Igor P.

2013-06-01

229

Fundamentals of Powder Compression. I. The Compactibility and Compressibility of Pharmaceutical Powders  

Microsoft Academic Search

In spite of the widespread use of tablets, the theoretical understanding of the tableting process has been limited. During the last decades considerable research has been done in the field of powder technology and compaction. A survey of the literature and compression equations reveals many studies on the characterization of powder properties, most of which relate to volume reduction under

Hans Leuenberger; Bhagwan Dass Rohera

1986-01-01

230

Particle size distribution by LASER diffraction spectrometry: application to cementitious powders  

E-print Network

components of the refractive index) of the solid phase which in cement is a multi-phase particle. The current. KEYWORDS: cement, gypsum, laser diffraction, particle size distribution #12;I. INTRODUCTION Portland cement routinely employed to characterize cement powders. A variety of techniques are available for this purpose

Bentz, Dale P.

231

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

Microsoft Academic Search

The goal of this CRADA was to combine the powder coating material and application techniques and laboratory testing capabilities of FM and T with the manufacturing, real-world testing, and practical knowledge available to BHI in a limited study to determine if coated stainless steel would provide the durability needed to justify additional work in this area. The coating materials chosen

2000-01-01

232

Parametric studies of the hot isostatic pressing of rapidly solidified 304 stainless steel powder  

Microsoft Academic Search

The increasing importance of powder materials fabrication by use of hot isostatic pressing (HIP) has led to recent emphasis on analytical techniques for describing and understanding the process. Understanding of particle consolidation during the HIP process has been attempted through the modeling of densification behavior by considering the deformation of a representative particle due to forces transmitted through the particle

W. Kim; J. E. Flinn; J. G. Byrne

1993-01-01

233

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

Microsoft Academic Search

The Large Hadron Collider to be built at CERN will require 1232 superconducting dipole magnets operating at 1.9 K. By virtue of their mechanical properties, weldability and improved austenite stability, nitrogen enriched austenitic stainless steels have been chosen as the material for several of the structural components of these magnets. Powder Metallurgy (PM) could represent an attractive production technique for

Stefano Sgobba; F Savary; J Liimatainen; M Kumpula

2000-01-01

234

Study of domain structure of magnetic powder particles by Mössbauer spectroscopy  

NASA Astrophysics Data System (ADS)

The determination technique of monodomain state of the magnetic powder particles using the Mössbauer spectroscopy is described. The method was verified on the particles of gadolinium iron garnet near the compensation temperature. It has also shown that using the Mössbauer spectroscopy we can evaluate the domain wall energy in ferrites possessing the compensation point.

Aliev, Sh. M.; Kamilov, I. K.; Guseynov, M. M.; Kallaev, S. M.; Aliev, M. Sh.; Mamedov, V. V.; Shakhshaev, Sh. O.

2010-02-01

235

Study of domain structure of magnetic powder particles by Mössbauer spectroscopy  

Microsoft Academic Search

The determination technique of monodomain state of the magnetic powder particles using the Mössbauer spectroscopy is described. The method was verified on the particles of gadolinium iron garnet near the compensation temperature. It has also shown that using the Mössbauer spectroscopy we can evaluate the domain wall energy in ferrites possessing the compensation point.

Sh. M. Aliev; I. K. Kamilov; M. M. Guseynov; S. M. Kallaev; M. Sh. Aliev; V. V. Mamedov; Sh. O. Shakhshaev

2010-01-01

236

Thermal desorption spectra of the PdHx system in a powder form  

Microsoft Academic Search

Thermal desorption spectroscopy (TDS) of hydrogen from metal hydrides is a technique where the rate of hydrogen desorption is measured as a function of temperature while the temperature is increased linearly with time. The authors present the TDS of a powdered PdHx (particle size approximately 2 mu m) for various initial concentrations and for various heating rates. The spectra develop

A. Stern; A. Resnik; D. Shaltiel

1984-01-01

237

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.

238

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

NASA Technical Reports Server (NTRS)

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

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

1971-01-01

239

Synthesis, formation and characterization of lead zinc niobate–lead zirconate titanate powders via a rapid vibro-milling method  

Microsoft Academic Search

In this study, an approach to synthesizing pyrochlore-free lead zinc niobate – lead zirconate titanate powders with a formula\\u000a xPb(Zn1\\/3Nb2\\/3)O3–(1???x)Pb(Zr1\\/2Ti1\\/2)O3 (when x?=?0.1–0.5) by a mixed oxide synthetic route via a rapid vibro-milling has been developed. The formation of perovskite phase\\u000a in calcined PZN-PZT powders has been investigated as a function of calcination temperature by TG-DTA and XRD techniques. Powder\\u000a morphology

A. Ngamjarurojana; O. Khamman; S. Ananta; R. Yimnirun

2008-01-01

240

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

241

Simulation of powder metal fabrication with high pressure gas atomization  

SciTech Connect

A computational/analytical technique has been developed which models the physics of high pressure gas atomization. The technique uses an uncoupled approach, such that the gas flowfield is initially calculated with a commercially-available Navier-Stokes code. The liquid metal droplet breakup, dynamics, and thermodynamics, are then calculated using the pre-computed flowfield by a separate computer program written by the authors. The atomization code models the primary breakup of the liquid metal stream, tracks the droplets resulting from primary breakup through the flowfield until they undergo secondary breakup, and then tracks the subdroplets until they breakup, solidify, or leave the flowfield region of interest. The statistical properties of the metal powder produced are then computed from the characteristics of these droplets. Comparisons between experimental measurements and computations indicate that the Navier-Stokes code is predicting the gas flowfield well, and that the atomization code is properly modeling the physics of the droplet dynamics and breakup.

Kuntz, D.W.; Payne, J.L.

1994-12-31

242

Dry polymer powder coating and comparison with conventional liquid-based coatings for Eudragit ® RS, ethylcellulose and shellac  

Microsoft Academic Search

Drug-layered pellets were coated with micronized polymer powders (Eudragit® RS, ethylcellulose, and shellac) by a dry powder coating technique as an alternative to organic- and aqueous-based coatings (Eudragit® RS 30D, Aquacoat® ECD) were investigated. High plasticizer concentrations (40%) and a thermal after-treatment (curing) were necessary for the coalescence of the polymer particles and good film formation. Ethylcellulose required a higher

Nantharat Pearnchob; Roland Bodmeier

2003-01-01

243

Fabrication and properties of rapidly solidified powder-based high-temperature application light-alloy composites  

Microsoft Academic Search

Particulate-reinforced composites based on Al-Fe-Ce and SiC were fabricated by conventional powder metallurgy techniques, namely powder mixing, cold compaction and hot extrusion. Static mechanical properties at ambient temperature and at elevated temperature after prolonged exposure to the test temperature were measured and related to process parameters and the volume fraction of the reinforcement. The addition of SiC particles in considerable

N. Raghunathan; H. B. Mcshane; C. Davies; T. Sheppard

1990-01-01

244

An investigation on the sintering behavior of 316L and 17-4PH stainless steel powders for graded composites  

Microsoft Academic Search

This paper presents the densification and microstructure of bilayer structures made from 316L and 17-4PH stainless steels powders during sintering. The requirements for such objects could be magnetic properties at one area of the part and non-magnetic properties at another area of the object. A pressureless solid state sintering method in conjunction with a powder layering technique was used. The

A. Simchi; A. Rota; P. Imgrund

2006-01-01

245

Reactive plasma atomization of aluminum nitride powder  

SciTech Connect

Experiments were performed to synthesize AlN powders by reacting Al with N using a conventional dc arc plasma as heat source. Feeding Al powder into Ar/N plasma open to atmosphere produced mainly Al oxide. Experiments using a chamber backfilled with nitrogen suppressed the Al oxide, but little AlN was formed. A furnace and crucible assembly was designed to feed molten Al directly into a DeLaval nozzle attached to the face of the dc arc plasma gun. Resulting submicron powders show a significant increase in AlN formation. This was dependent on chamber pressure, plasma velocity, and molten liquid feed rate. Experimental parameters, equipment design, effects of atomization/vaporization/condensation are discussed.

Prichard, P.; Besser, M.; Sordelet, D.; Anderson, I.

1997-02-01

246

Alternative carriers in dry powder inhaler formulations.  

PubMed

The aerosolization efficiency of a powder is highly dependent on carrier characteristics, such as particle size distribution, shape and surface properties. The main objective in the inhalation field is to achieve a high and reproducible pulmonary deposition. This can be provided by successful carrier selection and careful process optimization for carrier modification. Lactose is the most common and frequently used carrier in dry powder inhaler (DPI) formulations. But lactose shows some limitations in formulation with certain drugs and peptides that prohibit its usage as a carrier in DPI formulations. Here, we criticality review the most important alternative carriers to lactose with merits, demerits and applications in DPI formulations. PMID:24269834

Rahimpour, Yahya; Kouhsoltani, Maryam; Hamishehkar, Hamed

2014-05-01

247

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

248

Synthesis of ultrafine powders by microwave heating  

DOEpatents

A method of synthesizing ultrafine powders using microwaves is described. A water soluble material is dissolved in water and the resulting aqueous solution is exposed to microwaves until the water has been removed. The resulting material is an ultrafine powder. This method can be used to make Al.sub.2 O.sub.3, NiO+Al.sub.2 O.sub.3 and NiO as well as a number of other materials including GaBa.sub.2 Cu.sub.3 O.sub.x.

Meek, Thomas T. (Knoxville, TN); Sheinberg, Haskell (Los Alamos, NM); Blake, Rodger D. (Santa Fe, NM)

1988-01-01

249

Removing Undesired Fine Powder From Silicon Reactor  

NASA Technical Reports Server (NTRS)

Fluidized-bed reactor produces highly pure polycrystalline silicon particles with diameters approximately greater than 400 micrometers. Operates by pyrolysis of silane in reaction zone, which is bed of silicon seed particles fluidized by flow of silane and carrier gas. Above reaction zone, gas mixture flows rapidly enough to entrain silicon powders, but not larger seed and product particles. Entrained particles swept out of reactor. Applicable to other processes such as production of fine metal and ceramic powders where control of sizes of product needed.

Flagella, Robert N.

1992-01-01

250

Properties of chemical vapor infiltration diamond deposited in a diamond powder matrix  

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 have developed two techniques: electrophoretic deposition and screen printing, to form nonmined diamond powder precursors on substrates. They then densify these precursors in a hot filament assisted reactor. Analysis indicated that a hot filament assisted chemical vapor infiltration process forms intergranular diamond deposits with properties that are to some degree different from predominantly hot-filament-assisted CVD material.

Panitz, J.K.G.; Tallant, D.R.; Hills, C.R.; Staley, D.J.

1993-12-31

251

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

252

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

NASA Astrophysics Data System (ADS)

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

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

2012-10-01

253

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

254

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

255

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.; Möller, S.; Winkler, H.; Petry, R.; Meyer, H.-J.; Jüstela, T.

2014-05-01

256

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

257

Ripples in Tapped or Blown Powder  

Microsoft Academic Search

We observe ripples forming on the surface of a granular powder in a container submitted from below to a series of brief and distinct shocks. After a few taps, the pattern turns out to be stable against any further shock of the same amplitude. We find that the wavelength of the pattern is proportional to the amplitude of the shocks.

Jacques Duran; M. Curie

2000-01-01

258

Frontal dynamics of powder snow avalanches  

NASA Astrophysics Data System (ADS)

We analyze frontal dynamics of dilute powder snow avalanches sustained by rapid blow-out behind the front. Such material injection arises as a weakly cohesive snow cover is fluidized by the very pore pressure gradient that the particle cloud induces within the snowpack. We model cloud fluid mechanics as a potential flow consisting of a traveling source of denser fluid thrust into a uniform airflow. Stability analysis of a mass balance involving snow cover and powder cloud yields relations among scouring depth, frontal height, speed, mixed-mean density, and impact pressure when the frontal region achieves a stable growth rate. We compare predictions with field measurements, show that powder clouds cannot reach steady frontal speed on a uniform snowpack with constant cloud width and derive a criterion for cloud ignition. Because static pressure is continuous across the mean air-cloud interface and deviatoric stresses are negligible, frontal acceleration is insensitive to local slope, but instead arises from a deficit of flow-induced suction in the wake. We calculate how far a powder cloud travels until its frontal mixed-mean density becomes stable, and show how topographic spread can hasten its collapse.

Carroll, C. S.; Louge, M. Y.; Turnbull, B.

2013-06-01

259

USING POWDERED ACTIVATED CARBON: A CRITICAL REVIEW  

EPA Science Inventory

Because the performance of powdered activated carbon (PAC) for uses other than taste and odor control is poorly documented, the purpose of this article is to critically review uses that have been reported (i.e., pesticides and herbicides, synthetic organic chemicals, and trihalom...

260

High-Performance Polyimide Powder Coatings  

NASA Technical Reports Server (NTRS)

Researchers at NASA's Kennedy Space Center have developed advanced powder coatings for longer-lasting, improved corrosion control. The results of preliminary tests of the coatings and their resistance to salt spray corrosion are very encouraging, and commercial partners are sought for further development.

Leahy, Jonathan J.

2014-01-01

261

Magnetic properties of dispersed magnetite powders  

Microsoft Academic Search

Measurements have been made of coercive force, susceptibility, isothermal remanence, thermoremanence and thermal and alternating field demagnetization of annealed magnetite powders in nine size ranges from 1·5 ? to 120 ?. The samples were dispersed in plaster to occupy a few per cent by volume of the specimens and thus to simulate the magnetic properties of rocks. The results are

L. G. Parry

1965-01-01

262

Mixing of zeolite powders and molten salt  

Microsoft Academic Search

Transuranics and fission products in a molten salt can be incorporated into zeolite A by an ion exchange process and by a batch mixing or blending process. The zeolite is then mixed with glass and consolidated into a monolithic waste form for geologic disposal. Both processes require mixing of zeolite powders with molten salt at elevated temperatures (>700 K). Complete

C. Pereira; V. N. Zyryanov; M. A. Lewis; J. P. Ackerman

1996-01-01

263

Low density fragile states in cohesive powders  

NASA Astrophysics Data System (ADS)

We discuss the difference between cohesive and non-cohesive granular media in the context of dry quicksand, recently proposed as a new fragile state of sand. We demonstrate that weak low density configurations with properties like dry quicksand are readily formed in many common household powders. In contrast, such states cannot be formed in non-cohesive granular media such as ordinary sand.

Umbanhowar, Paul B.; Goldman, Daniel I.

2006-08-01

264

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

265

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...

266

Laboratory Powder Metallurgy Makes Tough Aluminum Sheet  

NASA Technical Reports Server (NTRS)

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

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

1993-01-01

267

Characterisation of high dose aerosols from dry powder inhalers.  

PubMed

Developments in high dose dry powder aerosol delivery will increasingly challenge the applicability of currently used aerosol characterisation techniques. With cascade impaction analysis bounce effects can negatively influence stage collection efficiency, especially with increasing impactor loads. In this study the suitability of the multi stage liquid impinger (MSLI) and the Next Generation Impactor (NGI) for the characterisation of dry powder aerosols containing up to 50mg of drug is evaluated. The occurrence of bounce effects is quantitatively assessed by comparison with data obtained from laser diffraction analysis. The liquid based impaction surfaces of the MSLI largely prevent bounce effects, but the low number of cut-off values associated with this impactor hinders accurate data interpretation. With the NGI, a standard high viscosity plate coating insufficiently reduces bounce effects, causing the fraction <1 ?m to be higher than what can maximally be expected based on the primary particle size distribution (PSD) obtained from RODOS dispersion. With this type of impactor, the use of solvent soaked filters as impaction surface is necessary to eliminate bounce effects. PMID:22939966

Grasmeijer, Floris; Hagedoorn, Paul; Frijlink, Henderik W; de Boer, Anne H

2012-11-01

268

Thermal analysis of the southern Powder River Basin, Wyoming  

SciTech Connect

Temperature and geologic data from over 3,000 oil and gas wells within a 180 km x 30 km area that transect across the southern Powder River Basin in Wyoming, U.S.A., were used to determine the present thermal regime of the basin. Three-dimensional temperature fields within the transect, based on corrected bottom-hole temperatures (BHTs) and other geologic information, were assessed using: (1) A laterally constant temperature gradient model in conjunction with an L{sub 1} norm inversion method, and (2) a laterally variable temperature gradient model in conjunction with a stochastic inversion technique. The mean geothermal gradient in the transect is 29 C/km, but important lateral variations in the geothermal gradient exist. The average heat flow for the southern Powder River Basin is 52 mW/m{sup 2} with systematic variations between 40 mW/m{sup 2} and 60 mW/m{sup 2} along the transect. Extremely high local heat flow (values up to 225 mW/m{sup 2}) in the vicinity of the Teapot Dome and the Salt Creek Anticline and low heat flow of 25 mW/m{sup 2} occurring locally near the northeast end of the transect are likely caused by groundwater movement.

McPherson, B.J.O.L.; Chapman, D.S. [Univ. of Utah, Salt Lake City, UT (United States). Dept. of Geology and Geophysics] [Univ. of Utah, Salt Lake City, UT (United States). Dept. of Geology and Geophysics

1996-11-01

269

In situ characterization of AIPO-14 using synchrotron powder diffraction.  

SciTech Connect

The separation of propane/propylene mixtures is an important yet difficult industrial process that can be accomplished by a pressure swing adsorption process using AlPO-14 as the adsorbent. Although the AlPO-14 structure has been studied with different techniques, the detailed structure under conditions of the adsorption process has not been clarified. We have used synchrotron x-ray powder diffraction and an in situ reactor system to obtain detailed structural information of AlPO-14 with the Rietvield method. Molecular modeling using the structural data allowed determination of the diffusion path of propylene in AlPO-14. The design of the in situ reactor system allows different chemicals to be loaded and the system to be heated and pressurized up to 90 psi with various gases or liquids. For this work, AlPO-14 powder was loaded into a 1 mm capillary tube and attached to the cell. Diffraction scans were collected during treatments in nitrogen, propane and propylene at various temperatures up to 300 C and various pressures up to 90 psig. A selected region of the x-ray diffraction patterns under different experimental conditions is shown in Fig.1. The diffraction patterns for AlPO-14 in nitrogen and propane are very similar, whereas the pattern in propylene changes considerably suggesting structure changes caused by adsorption of propylene into the pores.

Yang, N.; Greenlay, N.; Karapetrova, J.; Zschack, P.; Gatter, M.; Wilson, S.; Broach, R. W.; Experimental Facilities Division (APS); UOP

2006-01-01

270

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

271

Design of a fluid energy single vessel powder processor for pharmaceutical use.  

PubMed

This study introduces a motionless novel single vessel powder processor designed to carry out all of the unit operations in the preparation of powders for tableting. The processor used controllable fluid dynamics to provide the energy for each unit operation. The vessel design was evaluated using a computational fluid dynamics model which indicated the flow necessary for the intended processing operations to take place. The processor performance was evaluated experimentally for two unit processes: particle size reduction and dry powder mixing. The processor was found capable of reducing the size of lactose granules from a median particle diameter of 459 microm to a median particle diameter of 182 microm within 5 min under optimal process conditions. It was found that a formulation containing lactose granules (373 microm median particle diameter) and a model drug, sodium chloride (30 microm), could be mixed to an improved degree of homogeneity in comparison with equivalent powders blended using a conventional turbulent tumbling technique. It was concluded that a processor having controllable fluid dynamics offered the potential to perform multi-task processing of powders. PMID:10370220

Kay, G R; Staniforth, J N; Tobyn, M J; Horrill, M D; Newnes, L B; MacGregor, S A; Li, M; Atherton, G; Lamming, R C; Hajee, D W

1999-04-30

272

The effect of polymorphism on powder compaction and dissolution properties of chemically equivalent oxytetracycline hydrochloride powders.  

PubMed

In South Africa, oxytetracycline is identified as an essential drug; many generic products are on the market, and many more are being developed. In this study, six oxytetracycline hydrochloride powders were obtained randomly from manufacturers, and suppliers were compared. It was found that compliance to a pharmacopoeial monograph was insufficient to ensure the optimum dissolution performance of a simple tablet formulation. Comparative physicochemical raw material analysis showed no major differences with regard to differential scanning calorimetry (DSC), infrared (IR) spectroscopy, powder dissolution, and particle size. However, the samples could be divided into two distinct types with respect to X-ray powder diffraction (XRD) and thus polymorphism. The two polymorphic forms had different dissolution properties in water or 0.1 N hydrochloride acid. This difference became substantial when the dissolution from tablets was compared. The powders containing form A were less soluble than that containing form B. PMID:10518242

Liebenberg, W; de Villiers, M M; Wurster, D E; Swanepoel, E; Dekker, T G; Lötter, A P

1999-09-01

273

Synthesis of in-situ TiAl-based composites from elemental powders  

SciTech Connect

Alloys and composites based on the intermetallic compound TiAl are emerging as an important class of light-weight, high-temperature structural materials. Recently, it has been recognized that these alloys have applications in industries, such as the automotive industry, where cost is frequently a major concern in materials selection. However, for these alloys to be used in this type of application, new low cost methods for high volume component fabrication are required. One potential fabrication approach is reactive synthesis (also termed combustion synthesis). This technique involves initiating an self-propagating, high-temperature synthesis (SHS) reaction within an intimate mixture of elemental powders. This process has been used to fabricate intermetallics, ceramics and in-situ composites in the form of powders and dense monoliths. SHS reactions tend to initiate at low homologous temperatures of the forming compound (for aluminides near or at the melting point of Al, 660°C), and tend to go to completion in a short period of time (i.e., a few seconds). For some compounds, particularly aluminides, the reaction is ac companied by the formation of transient liquid phases. These factors can reduce the required processing parameters (time, temperature and pressure) needed to produce dense products by reactive synthesis techniques compared to conventional powder metallurgical approaches. This paper characterizes the reactions that occur and resultant microstructures of TiAl based composites fabricated from ternary mixtures of elemental Ti, Al and B or Si powders. Mixtures of the elemental powders were prepared corresponding to TiAl reinforced with 0, 10 25, 60 and 100 vol. pct. Ti5Si3 or TiB2. The powders were consolidated by reactive hot-pressing (at 1000°C and 20 MPa for 1 hr). It was found that the composites produced from Ti, Al and Si powders were dense, and the elemental powders transformed to the target phases of TiAl and Ti5Si3. Whereas, composites produced from the Ti, Al and B powders were porous and inhomogeneous, that is several aluminide (TiAl, Ti3Al and TiAl3) and boride phases (TiB2, AlB12, TiB) formed during hot-pressing. The different behavior observed by the two ternary systems can be attributed to both reaction sequence and phase diagram considerations. First, Differential Thermal Analysis (DTA) revealed that an endothermic reaction associated with the formation of Al-Si eutectic occurs prior to the initiation of an SHS reaction within the mixtures of Ti, Al and Si powders. No such pre-reaction melting occurred within the mixtures of Ti, Al, and B powders. Thus, the "extra" transient liquid phase that formed during the reaction between Ti, Al and Si systems enhances diffusion (hence homogenization) and densification within this system during reaction processing. Also, an examination of phase diagrams reveals that there exists no Al-Si compounds to compete with the formation of titanium-aluminide and titanium-silicides during reactions between Ti, Al and Si powders. However, there are several aluminum-boride phases that can compete with the formation of titanium-aluminide and titanium-boride during reactions between Ti, Al and B powders. The implications of this study is that TiAl-based composites can be designed for densification during reactive processing.

Alman, D.E.; Hawk, J.A.

1997-02-01

274

21 CFR 520.88d - Amoxicillin trihydrate soluble powder.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 false Amoxicillin trihydrate soluble powder. 520...ANIMAL DRUGS § 520.88d Amoxicillin trihydrate soluble powder. (a...Specifications. Each gram contains amoxicillin trihydrate equivalent to 115.4...

2010-04-01

275

Photocatalysis of phenol and salicyclic acid by nanostructured titania powders  

SciTech Connect

The photocatalytic destruction of phenol and salicylic acid was studied in aqueous suspensions of titania powders made in flame reactors. These powders were made in six hydrocarbon diffusion flames by hydrolysis and oxidation of TiCl{sub 4} that resulted in powders of high specific surface area and high anatase content. The photoactivity of the flame-made titania powders was compared with that of commercially available powders. Doping the titania with SiO{sub 2} was detrimental to the photoactivity of the powders in aerated solutions in contrast to non-aerated solutions. Titania powders in the range of 20-40 nm containing small amounts of rutile were more active than pure anatase powders. The phenol degradation reaction followed a first-order law while the Langmuir-Hinshelwood model was found to most accurately represent the photodegradation of salicylic acid.

Fotou, G.P.; Pratsinis, S.E. [Univ. of Cincinnati, OH (United States)

1995-12-31

276

Consolidation of aluminum 6061 powder by equal channel angular extrusion  

E-print Network

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

Pearson, John Montgomery

2012-06-07

277

Crystallization of Amorphous Components in Spray-Dried Powders  

Microsoft Academic Search

Spray-dried powders are typically produced as amorphous particles. Long storage of the particles tends to crystallize the powders, a reaction affected by moisture, time, and temperature. This work has examined partial crystallization from amorphous spray-dried powders by moisture sorption. Powders of citrus fiber with hibiscus extract, maltodextrin, coffee, tea, skim milk, and sucrose were produced with a laboratory-scale spray dryer.

D. Chiou; T. A. G. Langrish

2007-01-01

278

Powder segregation during the filling of a simple die  

E-print Network

POWDER SEGREGATION DURING THE FILLING OF A SIMPLE DIE A study of powder segregation during die filling with two component mixes of lead particles has shown that: I. Segregation occurs by fines filtering down through the moving powder mass. This effect... and density in the mixtures studied have little effect upon segrege. tion, 4. Increasing the rate of die filling decreases opportu- nity for segregation. 5. Increasing the height from which the powder falls into the die causes mixing and decreases...

Lawrence, Larry Raymond

2012-06-07

279

Measurement of strain heat in shock-loaded 304 stainless steel: implications to powder consolidation; oral presentation of full paper  

SciTech Connect

Over the past decades there have been numerous papers on the shock response of materials and more specifically towards metal powder compaction and consolidation. In general, the shock process for powdered materials has utilized the traditional pressure-volume shock relationships proportioned to the initial packing densities of the powders. However, this approach and its resulting data are in controversy due to the lack of knowledge of its associated particle strain and strain temperature uncertainties. This paper will describe the current understanding as well as the experimental technique used to obtain the shock response for distended materials. The above parameters are described within a pressure-strain-temperature interdependence. It was found that the experimentally measured strain heat was not only a function of initial packing density but also a function of powder size and distribution.

Staudhammer, Karl P.

2003-01-01

280

The thermal resistance of flat powder-filled evacuated panels  

SciTech Connect

The need to develop high thermal resistance insulations that do not use chlorofluorocarbons has resulted in renewed interest in evacuated powder-filled panel insulations. Evacuated panels containing small diameter milled perlite or silica particles have been studied using a linear heat flow measurement technique. Thermal resistivities (R-value for one-inch of thickness) as high as 19.3 ft/sup 2//center dot/h/center dot//degree/F/Btu-in. have been observed for silica panels. Thermal measurements completed for a commercially produced evacuated panel containing perlite have shown thermal resistivities from 9.0 to 18.1 ft/sup 2//center dot/h/center dot//degree/F/Btu-in. Thermal resistance measurements have been repeated to determine changes in thermal performance with time (aging). 8 refs., 7 figs., 3 tabs.

Graves, R.S.; Yarbrough, D.W.; McElroy, D.L.

1989-01-01

281

Powder metallurgy: Solid and liquid phase sintering of copper  

NASA Technical Reports Server (NTRS)

Basic powder metallurgy (P/M) principles and techniques are presented in this laboratory experiment. A copper based system is used since it is relatively easy to work with and is commercially important. In addition to standard solid state sintering, small quantities of low melting metals such as tin, zinc, lead, and aluminum can be added to demonstrate liquid phase sintering and alloy formation. The Taguchi Method of experimental design was used to study the effect of particle size, pressing force, sintering temperature, and sintering time. These parameters can be easily changed to incorporate liquid phase sintering effects and some guidelines for such substitutions are presented. The experiment is typically carried out over a period of three weeks.

Sheldon, Rex; Weiser, Martin W.

1993-01-01

282

Chemical Preparation of Carbonated Calcium Hydroxyapatite Powders at 37  

E-print Network

Chemical Preparation of Carbonated Calcium Hydroxyapatite Powders at 37 C in Urea-phase ceramic powder. Carbonated HA powders were formed from calcium nitrate tetrahydrate and di- ammonium properties. They were usually observed1 to be carbonate-substituted and calcium-de®cient. Synthetic body

Tas, A. Cuneyt

283

Fines Loadings in Milk Powder Plants with Washable Baghouses  

Microsoft Academic Search

Washable baghouses are increasingly used to filter the small size fractions of milk powder, known as fines, which become entrained with spray dryer outlet air streams in milk powder plants. Surprisingly, very little is known about the quantity of powder that becomes fines, an important parameter for both the control of agglomeration rates and washable bag-house design. A convenient method

J. R. Gabites; J. Abrahamson; J. A. Winchester

2007-01-01

284

Synthesis of titanium carbide nano-powders by thermal plasma  

Microsoft Academic Search

The paper presents a thermodynamic analysis for predicting the conditions for the plasma synthesis of TiC powders. The paper also investigates the effects of feeding rate and molar ratio. The experimental results show that TiC powders are synthesized by thermal plasma and the average size of the TiC powders is less than 100nm.

Lirong Tong; Ramana G. Reddy

2005-01-01

285

Comparison of Water Vapor Sorption by Milk Powder Components  

Microsoft Academic Search

Water vapor is absorbed by milk powder at sites dependent upon the relative pres- sure, P\\/Po, of the atmosphere to which the powder is exposed. Comparison of the water sorption isotherms for the protein, sugar, and mixed salts comparable with that found in milk powder indicated that at low P\\/Po water is bound primarily by the casein fraction in the

B. A. Anderson; M. J. Pallansch

1968-01-01

286

Barium strontium titanate powders prepared by spray pyrolysis  

Microsoft Academic Search

Ultasonic spray pyrolysis (SP) has been investigated for the production of the barium strontium titanate (BST) powders from the polymeric precursors. The processing parameters, such as flux of aerosol and temperature profile inside the furnace, were optimized to obtain single phase BST. The powders were characterized by the methods of X-ray diffraction analysis, SEM, EDS and TEM. The obtained powders

G. Brankovi?; Z. Brankovi?; M. S. Góes; C. O. Paiva-Santos; M. Cilense; J. A. Varela; E. Longo

2005-01-01

287

Hydrothermal synthesis of zinc oxide powders with controllable morphology  

Microsoft Academic Search

Crystalline zinc oxide powders with various morphologies have been prepared by hydrothermal treatment of zinc acetate in pure water, KOH or ammonia aqueous solution. It was found that the selected solvents play a different role in controlling the morphologies of the obtained powders. The variation of morphology of the obtained ZnO powder with solvents mainly depends on the different zinc

HaiYan Xu; Hao Wang; YongCai Zhang; WenLiang He; ManKang Zhu; Bo Wang; Hui Yan

2004-01-01

288

49 CFR 173.170 - Black powder for small arms.  

... 2 2014-10-01 2014-10-01 false Black powder for small arms. 173.170 Section 173...Materials Other Than Class 1 and Class 7 § 173.170 Black powder for small arms. Black powder for small arms that has been...

2014-10-01

289

IMPROVEMENT OF CONCRETE DURABILITY BY COMPLEX MINERAL SUPERFINE POWDER  

Microsoft Academic Search

The green concrete capable for sustainable development is characterized by application of industrial wastes to reduce consumption of natural resources and energy and pollution of the environment. KG powder is a complex mineral superfine powder made by grinding the mix of calcined coal gangue and slag in certain proportion. Through reaction with the concrete admixture, KG powder improved pozzolanic reaction,

Chen Han-bin; Chen Jian-xiong; Xiao Fei; Cui Hong-ta

290

Low temperature carburization of high surface area tungsten powders  

Microsoft Academic Search

Reductive decomposition of WO3 precursor powder gives high surface area ?-W at temperatures above 650 °C, ?-W at temperatures below 575 °C, and mixtures of ?-W and ?-W (in various ratios) at intermediate temperatures. The carburization behavior of these powders in flowing CO over the temperature range 350 °–700 °C is sensitive to the initial crystalline state of the powder.

L. Gao; B. H. Kear

1995-01-01

291

New Ferro Powder for Selective Laser Sintering of Dense Parts  

Microsoft Academic Search

The paper describes a new powder composition specially developed for selective laser sintering (SLS). The aim is to obtain a ferro powder that can be sintered without need for a (sacrificial) polymer binder and that results in quasi dense parts that do not need any post-processing like furnace sintering, infiltration or HIP. The powder is a mixture of different types

J. P. Kruth; L. Froyen; M. Rombouts; J. Van Vaerenbergh; P. Mercells

2003-01-01

292

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

NASA Technical Reports Server (NTRS)

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

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

2007-01-01

293

Powder formation of {gamma} uranium-molybdenum alloys via hydration-dehydration  

SciTech Connect

Gamma uranium-molybdenum alloys has been considered as fuel phase in plate type fuel elements for MTR reactors, mainly due to their acceptable performance under irradiation and metallurgical processing. To its use as a dispersion phase in aluminum matrix, a necessary step is the conversion of the as cast structure into powder, and one of the techniques considered at IPEN / CNEN - Brazil is HDH (hydration-dehydration). The alloys were produced by the induction melting technique, and samples were obtained from the alloys for the thermal treatments, under constant flow of hydrogen, for temperatures varying from 400 deg C to 600 deg C and times from 1 to 4 hours, followed by dehydration. A preliminary characterization of the powders was made and the curves of mass variation versus time were obtained and related to the powder characteristics. This paper describes the first results on the development of the technology to the powder formation of the (5 to 10) % weight molybdenum {gamma}-UMo alloys, and discusses some of its aspects, mainly those related to the {gamma} {yields} {alpha} equilibrium data. (author)

Vaz de Oliveira, Fabio Branco; Durazzo, Michelangelo; Fontenele Urano de Carvalho, Elita; Saliba-Silva, Adonis Marcelo [Instituto de Pesquisas Energeticas e Nucleares, Centro do Combustivel Nuclear, Avenida Professor Lineu Prestes 2242, Cidade Universitaria, 05508-900 Sao Paulo, Sao Paulo (Brazil); Gracher Riella, Humberto [Universidade Federal de Santa Catarina, Departamento de Engenharia Quimica, Campus Universitario 88040-900, Florianopolis, Santa Catarina (Brazil)

2008-07-15

294

Mixing of zeolite powders and molten salt  

SciTech Connect

Transuranics and fission products in a molten salt can be incorporated into zeolite A by an ion exchange process and by a batch mixing or blending process. The zeolite is then mixed with glass and consolidated into a monolithic waste form for geologic disposal. Both processes require mixing of zeolite powders with molten salt at elevated temperatures (>700 K). Complete occlusion of salt and a uniform distribution of chloride and fission products are desired for incorporation of the powders into the final waste form. The relative effectiveness of the blending process was studied over a series of temperature, time, and composition profiles. The major criteria for determining the effectiveness of the mixing operations were the level and uniformity of residual free salt in the mixtures. High operating temperatures (>775 K) improved salt occlusion. Reducing the chloride levels in the mixture to below 80% of the full salt capacity of the zeolite significantly reduced the free salt level in the final product.

Pereira, C.; Zyryanov, V.N.; Lewis, M.A.; Ackerman, J.P.

1996-05-01

295

Fabricating solid carbon porous electrodes from powders  

DOEpatents

Fabrication of conductive solid porous carbon electrodes for use in batteries, double layer capacitors, fuel cells, capacitive dionization, and waste treatment. Electrodes fabricated from low surface area (<50 m.sup.2 /gm) graphite and cokes exhibit excellent reversible lithium intercalation characteristics, making them ideal for use as anodes in high voltage lithium insertion (lithium-ion) batteries. Electrodes having a higher surface area, fabricated from powdered carbon blacks, such as carbon aerogel powder, carbon aerogel microspheres, activated carbons, etc. yield high conductivity carbon compositives with excellent double layer capacity, and can be used in double layer capacitors, or for capacitive deionization and/or waste treatment of liquid streams. By adding metallic catalysts to be high surface area carbons, fuel cell electrodes can be produced.

Kaschmitter, James L. (Pleasanton, CA); Tran, Tri D. (Livermore, CA); Feikert, John H. (Livermore, CA); Mayer, Steven T. (San Leandro, CA)

1997-01-01

296

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

297

Electrophoretic deposition of nanosized ceramic powders  

SciTech Connect

For nanosized powders the forming of compacts by electrophoretic deposition is an interesting method. In aqueous suspensions high deposition rates can be achieved at low electric fields. The problems with the gas bubble formation at the electrodes which are caused by the decomposition of water can be solved by depositing the compact on a microporous membrane in front of the electrode. Thus, with nanosized zirconia powders made by the flame hydrolysis (BET-surface area approx. 50 M{sup 2}/g) the deposition rate was measured as a function of deposition time and electrolyte concentration. Furthermore, the deposition rate depends on the effective electric field inside the suspension, which is much lower in zirconia suspensions than in comparable silica suspensions. In spite of this, deposition rates up to 0.5 g/min {center_dot} CM{sup 2} were achieved. The deposited compacts showed a small pore size distribution (max. 25 nm) and a relative green density of 40%.

Clasen, R.; Janes, S.; Oswald, C.; Ranker, D. [Institut fuer Neue Materialien gem GmbH, Saarbruechek (Germany)

1995-09-01

298

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

299

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

300

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

301

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

302

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

303

Fabricating solid carbon porous electrodes from powders  

DOEpatents

Fabrication is described for conductive solid porous carbon electrodes for use in batteries, double layer capacitors, fuel cells, capacitive deionization, and waste treatment. Electrodes fabricated from low surface area (<50 m{sup 2}/gm) graphite and cokes exhibit excellent reversible lithium intercalation characteristics, making them ideal for use as anodes in high voltage lithium insertion (lithium-ion) batteries. Electrodes having a higher surface area, fabricated from powdered carbon blacks, such as carbon aerogel powder, carbon aerogel microspheres, activated carbons, etc. yield high conductivity carbon composites with excellent double layer capacity, and can be used in double layer capacitors, or for capacitive deionization and/or waste treatment of liquid streams. By adding metallic catalysts to high surface area carbons, fuel cell electrodes can be produced. 1 fig.

Kaschmitter, J.L.; Tran, T.D.; Feikert, J.H.; Mayer, S.T.

1997-06-10

304

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

305

Shock compression response of magnetic nanocomposite powders  

Microsoft Academic Search

The shock compression response of magnetic Pr2Fe14B\\/?-Fe nanocomposite powders, pressed at different packing densities, was studied in the range of 11–23 GPa shock pressure, using a single-stage gas gun. Bulk compacts (97.5–99% dense) recovered in the form of 12 mm diameter by 4 mm thick disks, were analyzed to determine the structural changes occurring within the particles and at particle

Z. Q. Jin; K. H. Chen; J. Lia; H. Zeng; S.-F. Cheng; J. P. Liu; Z. L. Wang; N. N. Thadhani

2004-01-01

306

Tunable visible photoluminescence of powdered silica glass  

Microsoft Academic Search

Intense photoluminescence in the visible region was observed at room temperature in standard soda-lime-silica glass powder, mechanically milled in a high-energy attrition mill. The emission band maximum shows an interesting dependence on the exciting wavelength, suggesting the possibility to tune the PL emission. These findings indicate that the photoluminescence may be directly related to unsatisfied chemical bonds correlated with the

P. S. Pizani; M. R. Joya; F. M. Pontes; L. P. S. Santos; M GODINHOJR; E. R. Leite; E. Longo

2008-01-01

307

Porous materials from electrolytic chromium powder  

Microsoft Academic Search

Three fractions of electrolytic chromium powder, 0.2, 0.3, and 0.4 ram, were chosen for investigation. The designations of these fractions are highly arbitrary, because, for example, a thin lamellar particle up to 1 mm long can pass through a seive with 0.4-ram apertures. Metallographie examination (Fig. 1) and visual inspection revealed that, while the particles of the 0.2-ram fraction in

S. M. Solonin; V. B. Akimenko

1971-01-01

308

Properties of HIPed stainless steel powder  

Microsoft Academic Search

In the current design of ITER primary wall, 316LN stainless steel is the reference structural material. Austenitic stainless steel is used for water-cooling channels and structures. As material data on hot isostatic pressed (HIP) 316LN were not available in open literature and from powder producers, the main properties of unirradiated samples have been measured in CEA\\/CEREM. Fully dense material without

Ch. Dellis; G. Le Marois; J. M. Gentzbittel; G. Robert; F. Moret

1996-01-01

309

(Ln = Eu, Tb, and Dy) Powders  

NASA Astrophysics Data System (ADS)

BaWO4:Ln3+ powders were synthesized by a solid-state reaction method. The BaWO4:Ln3+ samples were characterized by x-ray powder diffraction (XRD) analysis, scanning electron microscopy (SEM), and luminescence spectroscopy. The XRD patterns reveal that the BaWO4:Ln3+ samples present pure tetragonal scheelite structure. The SEM observations demonstrate that the BaWO4:Ln3+ powders are irregular particles with size in the range of micrometers. The excitation spectra of the BaWO4:Ln3+ samples show the broad absorption band originating from charge transfer between oxygen ligands and the central tungstate ions inside WO{4/2-} groups in the metal tungstate. The emission spectra of the BaWO4:Ln3+ samples display the bands associated to the anion molecular complex (WO{4/2-}) and the f- f transitions of Ln3+. According to the emission spectra and the chromaticity coordinates (Commission internationale de l'éclairage, CIE), one can see that the BaWO4:Eu3+, BaWO4:Tb3+, and BaWO4:Dy3+ samples show emission in the red, green, and yellow region, respectively. The results show that the luminescence color can be altered by changing the Ln3+ doping in BaWO4 material.

Sun, Xiaoyu; Sun, Xiaodan; Li, Xingang; He, Jian; Wang, Binsheng

2014-09-01

310

Fabrication of Biochips with Micro Fluidic Channels by Micro End-milling and Powder Blasting  

PubMed Central

For microfabrications of biochips with micro fluidic channels, a large number of microfabrication techniques based on silicon or glass-based Micro-Electro-Mechanical System (MEMS) technologies were proposed in the last decade. In recent years, for low cost and mass production, polymer-based microfabrication techniques by microinjection molding and micro hot embossing have been proposed. These techniques, which require a proper photoresist, mask, UV light exposure, developing, and electroplating as a pre-process, are considered to have some problems. In this study, we propose a new microfabrication technology which consists of micro end-milling and powder blasting. This technique could be directly applied to fabricate the metal mold without any preprocesses. The metal mold with micro-channels is machined by micro end-milling, and then, burrs generated in the end-milling process are removed by powder blasting. From the experimental results, micro end-milling combined with powder blasting could be applied effectively for fabrication of the injection mold of biochips with micro fluidic channels.

Yun, Dae Jin; Seo, Tae Il; Park, Dong Sam

2008-01-01

311

The Manufacture of Spherical Titanium Alloy Powder in Plasma  

NASA Astrophysics Data System (ADS)

In this study, the preparation technology of spherical titanium alloy powder (tc4) was studied by using continuous induction plasma powder synthesis system. The flow-ability, particle size and impurity content of the powder before and after plasma treatment were measured and compared. The result showed that, by applying induction plasma preparation technology, the powder's flow-ability was improved by 20% while oxygen and carbon content were decreased significantly. The powder's sphericization rate and recovery rate were above 95% and 90% respectively with plasma spherical treatment.

Wei, Huang; Ziming, Chen; Yong, Liu; Fujun, Shang; Weiming, Huang

2014-08-01

312

Properties of Hot Pressed Titanium Alloy Powders for Cryogenic Applications.  

NASA Technical Reports Server (NTRS)

Evaluation of strength and toughness of hot-pressed titanium alloy powders at room and at cryogenic temperatures. The purpose was to determine how the mechanical properties of solid bodies formed from powder would compare with wrought specimens of the same size and with the same chemical analysis. It was found that of five titanium powder-making processes investigated, only the Rotating Electrode Process (REP) was capable of producing ELI-grade titanium alloy powder. Blocks hot-pressed from spherical REP powders had tensile properties equivalent to or better than those obtained from wrought bar.

Friedman, G. I.; Kazaroff, J. M.

1970-01-01

313

Counterflow diffusion flame synthesis of ceramic oxide powders  

DOEpatents

Ceramic oxide powders and methods for their preparation are revealed. Ceramic oxide powders are obtained using a flame process whereby one or more precursors of ceramic oxides are introduced into a counterflow diffusion flame burner wherein the precursors are converted into ceramic oxide powders. The nature of the ceramic oxide powder produced is determined by process conditions. The morphology, particle size, and crystalline form of the ceramic oxide powders may be varied by the temperature of the flame, the precursor concentration ratio, the gas stream and the gas velocity.

Katz, Joseph L. (Baltimore, MD); Miquel, Philippe F. (Towson, MD)

1997-01-01

314

77 FR 28252 - Oral Dosage Form New Animal Drugs; Change of Sponsor; Griseofulvin Powder; Levamisole...  

Federal Register 2010, 2011, 2012, 2013

...Change of Sponsor; Griseofulvin Powder; Levamisole Hydrochloride Powder; Oxytetracycline...ANADAs) for griseofulvin powder, levamisole hydrochloride soluble powder, and oxytetracycline...and ANADAs 200-313 and 200-386 for Levamisole Hydrochloride Soluble Pig Wormer...

2012-05-14

315

[Making tablets of powdered milk and the physical properties].  

PubMed

Compressed baby milk powder has proven to be very convenient for parents due to the ease with which it can be handled, and the fact that use of a measuring scoop is not necessary. The purpose of this study was to develop a compressed baby milk powder and analyze the resulting physical properties. The basic production process consisted of the following steps: 1) molding milk powder by low compression pressure, 2) humidification at 25°C·97%RH and 3) drying with use of a desiccant. No chemical additives were used for solidification; therefore the chemical composition of the compressed milk powder is identical to the base milk powder. The important properties of the compressed milk powder are both ready solubility and the strength of the solid. The compressed milk powder obtained at low pressure was too brittle for practical use, but the strength was increased by humidification followed by drying. During the humidification process, the powder particles located close to the surface of the compressed milk powder partially dissolve resulting in bridging structures between the particles, leading to an increase in strength. Both specific surface area and the volume ratio of the compressed milk powder decreased. Testing showed that caking between the particles occurred following humidification, and that the volume of caking affected the ease with which the compressed milk powder dissolves in water. PMID:21963978

Shibata, Mitsuho; Otsubo, Kazumitsu; Nakane, Shota; Niwa, Toshiyuki; Danjo, Kazumi

2011-01-01

316

The effects of polymer pigmentation on fingermark development techniques.  

PubMed

The effectiveness of latent fingerprint development techniques is heavily influenced by the physical and chemical properties of the deposition surface. The use of powder suspensions is increasing for development of prints on a range of surfaces. We demonstrate that carbon powder suspension development on polymers is detrimentally affected by the presence of common white pigment, titanium dioxide. Scanning electron microscopy demonstrates that patches of the compound are clearly associated with increased levels of powder adhesion. Substrates with nonlocalized titanium dioxide content also exhibit increased levels of carbon powder staining on a surface-wide basis. Secondary ion mass spectrometry and complementary techniques demonstrate the importance of levels of the pigment within the top 30 nm. The association is independent of fingermark deposition and may be related to surface energy variation. The detrimental effect of the pigment is not observed with small-particle reagent (MoS2 SPR) or cyanoacrylate (superglue) fuming techniques that exploit different development mechanisms. PMID:23822671

Bacon, Simon R; Ojeda, Jesus J; Downham, Rory; Sears, Vaughn G; Jones, Benjamin J

2013-11-01

317

Growth, spectral and thermal studies of an efficient NLO material: Diaquadicinnamatocadmium(II)  

NASA Astrophysics Data System (ADS)

A nonlinear metal-organic crystal, diaquadicinnamatocadmium(II) has been grown by controlled gel diffusion technique. Sodium metasilicate was used to prepare the gel. The chemical composition of the crystal has been determined by CHN analysis. Powder X-ray diffraction studies confirm the crystalline nature of the grown crystal. Functional groups present in the compound were identified by FT-IR spectral analysis. The thermal decomposition of the compound was studied using thermogravimetry (TG). The optical transparency range and the lower cut-off wavelength were identified from the UV-Visible-NIR spectrum. The NLO activity of the grown crystal was confirmed using Kurtz and Perry powder test.

Roy, Sunalya M.; Sudarsanakumar, M. R.; Dhanya, V. S.

2014-01-01

318

The thermal resistance of fine powders at atmospheric pressure and under vacuum  

SciTech Connect

Heat transport measurements are reported on candidate insulation systems with relatively high thermal resistances for use in appliances. The thermal resistances of small diameter silica powders at atmospheric pressure and under vacuum were measured from 295 to 340 K using unguarded radial heat flow techniques. The thermal resistances of rectangular panels containing perlite or silica powder at reduced pressure were determined using an unguarded linear heat flow technique. Values of 1.2m/sup 2//center dot/K/W for 0.0254 m (R-7 per inch) were obtained at atmospheric pressure for powders of pure, fumed, amorphous 0.01 ..mu..m dia silica particles compacted to about 10% of theoretical density. Values of 0.7 m/sup 2//center dot/K/W for 0.0254 m (R-4 per inch) were obtained at atmospheric pressure for powders of impure, amorphous (0.3 ..mu..m dia) silica particles. Under vacuum these particle systems yielded thermal resistances as high as 6 m/sup 2//center dot/K/W for 0.0254 m (R-34 per inch), and mixtures with the pure silica particles yielded over 9 m/sup 2//center dot/K/W for 0.0254 m (R- 50 per inch). Evacuated panels of pure silica particles yielded thermal resistance values over 3 m/sup 2//center dot/K/W for 0.0254 m (R-17 per inch) and decreased about 5% in resistance in 39 months. Evacuated panels of a perlite powder yielded similar values. 18 refs, 8 figs, 2 tabs.

McElroy, D.L.; Weaver, F.J.; Yarbrough, D.W.; Graves, R.S.

1987-01-01

319

Synthesis of tungsten carbide by dynamic shock compression of a tungsten–acetylene black powder mixture  

Microsoft Academic Search

In order to synthesize tungsten carbide as a high-temperature structural element by a shock wave technique, a tungsten–acetylene black powder mixture was shock-compressed. The retrieved sample was examined by X-ray diffraction analysis and optical\\/electron microscopy. A rodlike compact consisting of rounded particles, plates and dendritic particles of WC having a hexagonal structure was formed in the central region of the

Kenjiro Yamada

2000-01-01

320

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

321

Selection of ferrite powder for thermal coagulation therapy with alternating magnetic field  

Microsoft Academic Search

Selection of ferrite powder was carried out to realize a thermal coagulation technique in which tumors are locally heated by an application of alternating magnetic field from external coils. Magnesium ferrite (MgFe2O4) showed the largest increase in temperature (?T) under an alternating magnetic field in all the ferrites examined. For all the samples, ?T value under alternating magnetic field was

T. Maehara; K. Konishi; T. Kamimori; H. Aono; H. Hirazawa; T. Naohara; S. Nomura; H. Kikkawa; Y. Watanabe; K. Kawachi

2005-01-01

322

Acid\\/epoxy reaction catalyst screening for low temperature (120 °C) powder coatings  

Microsoft Academic Search

This paper describes efforts to identify and screen suitable acid\\/epoxy reaction catalysts for low temperature curing (?120°C) powder coatings including tertiary amines, ammonium compounds, and metal complexes. Thermal analysis techniques were developed to aid evaluation of catalyst efficacy and a statistical design of experiments was carried out to study several commercially available catalysts. In three different resin\\/crosslinker systems, the effect

Glen Merfeld; Chris Molaison; Rainer Koeniger; A. Ersin Acar; Steve Mordhorst; Joe Suriano; Pat Irwin; Ron Singh Warner; Ken Gray; Mark Smith; Kevin Kovaleski; Greg Garrett; Steve Finley; Debora Meredith; Mike Spicer; Tom Naguy

2005-01-01

323

High density net shape components by direct laser re-melting of single-phase powders  

Microsoft Academic Search

Direct Metal Laser Re-Melting is a variant of the Selective Laser Sintering process, a Rapid Prototyping (RP) technology. This tool-less manufacturing technology has the potential of producing complex, high quality components from single-phase metal powders in short time scales. This is made possible by the production of consecutive two-dimensional layers. Unfortunately, finished components manufactured by this technique have their integrity

R. H. Morgan; A. J. Papworth; C. Sutcliffe; P. Fox; W. O'neill

2002-01-01

324

Evaluation of Raney-nickel cathodes prepared with aluminum powder and titanium hydride powder  

SciTech Connect

Raney-nickel (Ni) cathodes were prepared on nickel wire from aluminum powder and titanium hydride powder by heat-treatment. The influence of the addition of titanium to the Raney-Ni electrode on the polarization characteristics of the hydrogen evolution reaction was studied in 1 M NaOH at 303 K. Although the coated layer was composed of nickel with a small amount of aluminum and titanium, the titanium was enriched the most. The relative surface area of the Raney-Ni cathodes was about 3500 independent of the presence of titanium, but titanium could decrease the hydrogen overpotential.

Tanaka, Shinichi [Tokyo Metropolitan Industrial Technology Research Inst. (Japan)] [Tokyo Metropolitan Industrial Technology Research Inst. (Japan); [Kyoto Univ. (Japan). Inst. of Advanced Energy; Hirose, Norimitsu; Tanaki, Toshiyuki [Tokyo Metropolitan Eastern District Small and Medium-Sized Business Promotion Center (Japan)] [Tokyo Metropolitan Eastern District Small and Medium-Sized Business Promotion Center (Japan)

1999-07-01

325

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

326

Consolidation of Bi-2223 superconducting powders by spark plasma sintering  

NASA Astrophysics Data System (ADS)

The spark plasma sintering (SPS) technique, by using a compacting pressure of 50 MPa, was used to consolidate pre-reacted powders of Bi1.65Pb0.35Sr2Ca2Cu3O10+? (Bi-2223). The influence of the consolidation temperature, TD, on the structural and electrical properties has been investigated and compared with those of a reference sample synthesized by the traditional solid-state reaction method and subjected to the same compacting pressure. From the X-ray diffraction patterns, performed in both powder and pellet samples, we have found that the dominant phase is the Bi-2223 in all samples but traces of the Bi2Sr2CaCu2O8+x (Bi-2212) were identified. Their relative density were ˜85 % of the theoretical density and the temperature dependence of the electrical resistivity, ?(T), indicated that increasing TD results in samples with low oxygen content because the SPS is performed in vacuum. Features of the ?(T) data, as the occurrence of normal-state semiconductor-like behavior of ?(T) and the double resistive superconducting transition, are consistent with samples comprised of grains with shell-core morphology in which the shell is oxygen deficient. The SPS samples also exhibited superconducting critical current density at 77 K, Jc(77K), between 2 and 10 A /cm2, values much smaller than ˜ 22 A/cm2 measured in the reference sample. Reoxygenation of the SPS samples, post-annealed in air at different temperatures and times, was found to improve their microstructural and transport properties. Besides the suppression of the Bragg peaks belonging to the Bi-2212 phase, the superconducting properties of the post-annealed samples and particularly Jc(77K) were comparable or better than those corresponding to the reference sample. Post-annealed samples at 750 °C for 5 min exhibited Jc(77K) ˜130 A /cm2 even when uniaxially pressed at only 50 MPa.

Govea-Alcaide, E.; Machado, I. F.; Bertolete-Carneiro, M.; Muné, P.; Jardim, R. F.

2012-12-01

327

Low-Cobalt Powder-Metallurgy Superalloy  

NASA Technical Reports Server (NTRS)

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

Harf, F. H.

1986-01-01

328

Ampicillin Trihydrate from Synchrotron Powder Diffraction Data  

SciTech Connect

The crystal structure of ampicillin trihydrate {l_brace}systematic name: 6-[D(-)-{alpha}-aminophenylacetamido]penicillanic acid trihydrate{r_brace}, C{sub 16}H{sub 19}N{sub 3}O{sub 4}S{center_dot}3H{sub 2}O, a broad-spectrum {beta}-lactam antibiotic of the aminopenicillin type, has been determined from synchrotron X-ray powder diffraction data. The three water molecules form an infinite hydrogen-bonded chain through the crystal structure, with hydrogen bonds to the NH{sub 3}{sup +}, COO{sup -}, C{double_bond}O and NH groups of the ampicillin molecules.

Burley,J.; van de Streek, J.; Stephens, P.

2006-01-01

329

Effective temperature of an aging powder.  

PubMed

The aging dynamics and the fluctuation-dissipation relation between the spontaneous diffusion induced by a random noise and the drift motion induced by a small stirring force are numerically investigated in a 3D schematic model of compacting powder: a gravity-driven lattice-gas with purely kinetic constraints. The compaction dynamics is characterized by a super-aging behavior and, in analogy with glasses, exhibits a purely dynamical time-scale-dependent effective temperature. A simple experiment to measure this quantity is suggested. PMID:11415060

Sellitto, M

2001-06-01

330

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

331

Application of focused ion beam to atom probe tomography specimen preparation from mechanically alloyed powders.  

PubMed

Focused ion-beam milling has been applied to prepare needle-shaped atom probe tomography specimens from mechanically alloyed powders without the use of embedding media. The lift-out technique known from transmission electron microscopy specimen preparation was modified to cut micron-sized square cross-sectional blanks out of single powder particles. A sequence of rectangular cuts and annular milling showed the highest efficiency for sharpening the blanks to tips. First atom probe results on a Fe95Cu5 powder mechanically alloyed in a high-energy planetary ball mill for 20 h have been obtained. Concentration profiles taken from this powder sample showed that the Cu distribution is inhomogeneous on a nanoscale and that the mechanical alloying process has not been completed yet. In addition, small clusters of oxygen, stemming from the ball milling process, have been detected. Annular milling with 30 keV Ga ions and beam currents >or=50 pA was found to cause the formation of an amorphous surface layer, whereas no structural changes could be observed for beam currents

Choi, Pyuck-Pa; Al-Kassab, Tala'at; Kwon, Young-Soon; Kim, Ji-Soon; Kirchheim, Reiner

2007-10-01

332

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

NASA Astrophysics Data System (ADS)

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 °C had a predominance of vernier orthorhombic Y6O5F8 phase, while samples heat treated at 800 °C crystallized in stoichiometric rhombohedral YOF phase. The samples were doped with luminescent europium trivalent ions (Eu3+) in different concentrations (1-15 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 Eu3+:Y6O5F8 samples presented higher LQE in spite of the larger local crystal field anisotropy found for Eu3+:YOF samples.

Rakov, Nikifor; Guimarães, R. B.; Lozano B., W.; Maciel, Glauco S.

2013-07-01

333

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

334

Powder synthesis, fabrication, and transport properties of long-length Ag clad Bi-2223 conductors  

SciTech Connect

Prereacted, polyphase powders of Pb-doped Bi-Sr-Ca-Cu-O (2223) were prepared by the solid-state reaction of appropriate amounts of Bi{sub 2}O{sub 3}, PbO, SrCO{sub 3}, CaCO{sub 3}, and CuO. The calcined powders were characterized by thermal analysis, x-ray diffraction and scanning electron microscopy. The powders were then used to fabricate long lengths of flexible Ag-clad 2223 superconductor tapes, via the powder-in-tube technique. Growth of the 2223 phase in the tapes at each heat-treatment step has been studied. At 4.2 and 27 K improved process conditions yielded transport critical current density (J{sub c}) values greater than 10{sup 5} A/cm{sup 2} at zero field; at 77 K, J{sub c} exceeded 4 {times} 10{sup 4} A/cm{sup 2}. Long tapes (up to 70 m in length) have been fabricated and cowound into superconducting pancake coils and their transport properties have been characterized at 4.2, 27, 64 and 77 K.

Iyer, A.N.; Balachandran, U. [Argonne National Lab., IL (United States); Haldar, P.; Hoehn, J.G. Jr. [Intermagnetics General Corp., Guilderland, NY (United States); Motowidlo, L.R. [IGC Advanced Superconductors, Inc., Waterbury, CT (United States)

1993-10-01

335

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 °C had a predominance of vernier orthorhombic Y{sub 6}O{sub 5}F{sub 8} phase, while samples heat treated at 800 °C crystallized in stoichiometric rhombohedral YOF phase. The samples were doped with luminescent europium trivalent ions (Eu{sup 3+}) in different concentrations (1–15 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-Ciência dos Materiais, Universidade Federal do Vale do São Francisco, 48902-300 Juazeiro, BA (Brazil)] [PG-Ciência dos Materiais, Universidade Federal do Vale do São Francisco, 48902-300 Juazeiro, BA (Brazil); Guimarães, R. B.; Maciel, Glauco S. [Instituto de Física, Universidade Federal Fluminense, 24210-346 Niterói, RJ (Brazil)] [Instituto de Física, Universidade Federal Fluminense, 24210-346 Niterói, RJ (Brazil); Lozano B, W. [Departamento de Física, Universidade Federal de Pernambuco, 50670-901 Recife, PE (Brazil)] [Departamento de Física, Universidade Federal de Pernambuco, 50670-901 Recife, PE (Brazil)

2013-07-28

336

Doped nanocrystalline ZnO powders for non-linear resistor applications by spray pyrolysis method.  

PubMed

Homogeneous and doped nanocrystalline ZnO powders (30-200 nm) were synthesized by spray pyrolysis technique. The spray pyrolysed powders were calcined in the temperature range of 500-750 degrees C. Formation of insulating pyrochlore phase started from 700 degrees C during the calcination itself. The calcined powders were compacted and sintered at different temperatures ranging from 900-1200 degrees C for 0.5-4 h. The densification behavior was found to be dependent on calcination temperature of the nanopowder. The resulting discs were found to have density (5.34-5.62 g/cc) in the range of 96-99% of theoretical density. The breakdown voltage value obtained for the nanopowder based non-linear resistor is 10.3 kV/cm with low leakage current density of 0.7 microA/cm2 and coefficient of nonlinearity as high as 193. The activation energy for grain growth of the doped ZnO nanopowder powders is 449.4 +/- 15 kJ/mol. PMID:19916460

Hembram, Kaliyan; Vijay, R; Rao, Y S; Rao, T N

2009-07-01

337

The preference of protein powders among adult male and females: A protein powder taste study  

Microsoft Academic Search

Protein is essential in one's diet because it is an important component in many organs and tissues throughout the body. Athletes ingest protein in order to stimulate protein synthesis and increase lean muscle mass. In order to assist with obtaining adequate amounts of protein, athletes and bodybuilders purchase supplemental protein in the form of protein powders. Protein metabolism and digestion

Joshua Manter

2010-01-01

338

Numerical investigation of coarse powder and air flow in an electrostatic powder coating process  

Microsoft Academic Search

The work presented here reports on the numerical simulation of an electrostatic powder coating process that uses a commercial computational fluid dynamic code, FLUENT v6.1. The purpose of this study was to understand the gas and particle flow fields inside a coating booth under given operating conditions and the effect of particle sizes on its trajectories and the final coating

U. Shah; J. Zhu; C. Zhang; J NOTHERSENIOR

2006-01-01

339

Method for preparing metal powder, device for preparing metal powder, method for processing spent nuclear fuel  

DOEpatents

A method for producing metal powder is provided the comprising supplying a molten bath containing a reducing agent, contacting a metal oxide with the molten bath for a time and at a temperature sufficient to reduce the metal in the metal oxide to elemental metal and produce free oxygen; and isolating the elemental metal from the molten bath.

Park, Jong-Hee (Clarendon Hills, IL)

2011-11-29

340

The characteristics of aluminium-doped zinc oxide films prepared by pulsed magnetron sputtering from powder targets  

Microsoft Academic Search

Mixed zinc oxide and alumina powder targets have been used to prepare transparent semi-conductive films on glass by pulsed magnetron sputtering. The structure, crystallinity, optical properties, electrical properties and adhesion of the films were investigated using a range of techniques, including SEM, XRD, spectrophotometry, four-point probe and scratch adhesion testing. Also, the properties of the coatings before and after annealing

Y. Zhou; P. J. Kelly; A. Postill; O. Abu-Zeid; A. A. Alnajjar

2004-01-01

341

Experimental Study of the Basic Process Mechanism for Direct Selective Laser Sintering of LowMelting Metallic Powder  

Microsoft Academic Search

Due to the still limited mechanical properties of the materials which can be processed using industrially available rapid prototyping techniques, work is currently being undertaken to develop methods of manufacturing metallic prototypes directly. This paper reports on the process development of Selective Laser Sintering (SLS) for direct sintering of bronze as a low-melting metallic powder on a laboratory test facility.

Yong-Ak Song; Wilfried Koenig

1997-01-01

342

Physical properties of yoghurt powder produced by spray drying.  

PubMed

The study is an extension of an optimization study, which was planned to determine the optimum spray drying conditions (the feed, outlet and inlet air temperatures) for producing yoghurt powder. The resulting yoghurt powder at each condition was subjected to the measurement of physical properties, moisture content, and reconstitution properties. All the reconstitution properties of yoghurt powders produced under 20 different spray drying conditions according to CCRD experimental design were affected by the drying outlet temperature only. Furthermore, the bulk (bulk and tapped densities, porosity, flowability, hygroscopicity and degree of caking) and particle properties (particle size distribution, particle density and morphology) of yoghurt powder obtained from optimum spray drying conditions were also determined. The bulk, tapped and particle densities of yoghurt powder were 538, 746 and 1177 kg/m(3), respectively. The mean diameter (D4.3) and the span value of yoghurt powder were 3.053 and 2.487 ?m, respectively. PMID:24966433

Koç, Banu; Sakin-Y?lmazer, Melike; Kaymak-Ertekin, Figen; Balk?r, P?nar

2014-07-01

343

Amorphous powders of Al-Hf prepared by mechanical alloying  

SciTech Connect

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

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

1988-01-01

344

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

345

Epoxy powder coatings containing polyaniline for enhanced corrosion protection  

Microsoft Academic Search

Incorporation of polyaniline (PANI) in epoxy type powder coating formulations has not been attempted earlier. Using specific grade of PANI with low doping, it can be incorporated in epoxy powder coating formulations by twin screw extrusion process. The powder formulations were deposited on steel substrates by electrostatic spray coating at ?60kV and baked at 140°C for 20min. These were extensively

S. Radhakrishnan; Narendra Sonawane; C. R. Siju

2009-01-01

346

The prediction of moisture sorption isotherms for dairy powders  

Microsoft Academic Search

Moisture sorption isotherms were measured for whey protein isolate, high micellar casein and a milk protein concentrate powder. No temperature dependence was observed over the temperature range of 4–37°C. At 50°C the powders absorbed less moisture than observed at the lower temperatures. These isotherms were used to predict the isotherms for freeze-dried amorphous lactose\\/casein\\/whey protein powders. An isotherm for micellar

Kylie D. Foster; John E. Bronlund

2005-01-01

347

Sonoelectrochemical synthesis of submicron metal powders  

E-print Network

Pulsed sonoelectrochemical synthesis is a widely used technique for producing nanoparticles. In this technique, alternating pulses of electric current and power ultrasound are applied to an electrochemical cell to create ...

Reneker, Joseph (Joseph William)

2012-01-01

348

Joining of parts via magnetic heating of metal aluminum powders  

DOEpatents

A method of joining at least two parts includes steps of dispersing a joining material comprising a multi-phase magnetic metal-aluminum powder at an interface between the at least two parts to be joined and applying an alternating magnetic field (AMF). The AMF has a magnetic field strength and frequency suitable for inducing magnetic hysteresis losses in the metal-aluminum powder and is applied for a period that raises temperature of the metal-aluminum powder to an exothermic transformation temperature. At the exothermic transformation temperature, the metal-aluminum powder melts and resolidifies as a metal aluminide solid having a non-magnetic configuration.

Baker, Ian

2013-05-21

349

Multiple-Quantum NMR Coherence Growth in Single-Crystal and Powdered Calcium Fluoride  

NASA Astrophysics Data System (ADS)

Powdered and oriented single-crystal calcium fluoride (CaF 2) samples were used to determine the orientational dependence of 19F multiple-quantum (MQ) NMR coherence development in the absence of variations in lattice spacing and molecular motion on the experimental time scale. The normalized n-quantum coherence intensities and resultant effective spin-cluster size [ N(?)] of the powdered sample were found to be reproducible and insensitive to the cycle time chosen for the underlying eight-pulse MQ excitation sequence. Oscillations in the time-dependent 0Q and 2Q coherence intensities are seen in the oriented single-crystal samples. However, these oscillations are absent in the powdered CaF 2 sample, indicating damping by its orientational-based dipolar-coupling distribution. However, monotonic growth of the effective number of correlated nuclei, N(?), is still observed. In addition, the applicability of an average product-operator model of coherence growth based on the dimensionality of spin distribution, and previously only applied to powders, is tested for oriented single-crystal CaF 2 samples. The powdered and (100)-oriented single crystal show good agreement with the model, while the growth from the (111) orientation is slightly faster than predicted. This difference most likely arises from the unusual dipole structure of the (111)-oriented crystal, where nearest-neighbor couplings become zero. In addition, the refocused MQ signal intensity ( fMQ) is adversely effected by increasing the number of pulses applied in a fixed MQ preparation time. An empirical prediction of fMQ for samples with a static dipolar field is developed and serves as a basis for predicting the effects of motion on this MQ refocusing fraction. This relationship may also provide some insight into the possibility of extending the MQ technique to study correlations over larger length scales as the relatively rapid decay of fMQ typical limits the present experiment to ˜ 10 Å length scales.

Lathrop, D. A.; Handy, E. S.; Gleason, K. K.

350

Hafnium- and titanium-coated tungsten powders for kinetic energy penetrators, Phase I, SBIR. Final report  

SciTech Connect

Depleted uranium (DU) is the state-of-the-art material for kinetic energy penetrators used to defeat steel and composite armors. DU alloys, however, are costly to fabricate, handle, and store because of their extremely complex metallurgy and the obvious health considerations associated with the use of uranium. Tungsten composite materials are also used in kinetic energy penetrators, offering easier and safer fabrication, handling, and storage but to date lacking the performance of DU. The mechanisms by which a penetrator defeats an armor are difficult to determine, either experimentally or from first principles. Recent experiments have identified the presence of an adiabatic shear mechanism that appears to be important in the penetration of rolled homogeneous armor (RHA) by DU penetrators. In this program, Ultramet proposed to apply hafnium and titanium coatings to tungsten powder (Wp) particles by chemical vapor deposition (CVD) using an established fluidized-bed powder coating technique. Both hafnium and titanium are known to exhibit the adiabatic shear phenomenon. High strain rate experiments (approx.10 to the 4th power/sec) were performed on Ti(6A1-4V) and hafnium materials in order to establish the presence or absence of this mode of deformation in small cylindrical specimens. In addition, specimens of 2 wt% CVD Hf/Wp and 2 wt% CVD Hf + 8 wt% powder-mixed Hf/Wp were tested at high strain rate conditions (approx. 10 to the 4th power/sec). Tungsten powders, Composites, Chemical Vapor Deposition(CVD), Microstructure, Hafnium, Titanium, Dynamic tests, Strain rate testing, Powder metallurgy.

Williams, B.E.; Stiglich, J.J.

1992-05-01

351

Diamagnetic properties of YBa 2Cu 3O 7-? presintered powders: Critical current densities and a.c. losses  

NASA Astrophysics Data System (ADS)

The intrinsic diamagnetic response of YBa 2Cu 3O 7-? presintered powders obtained by the citrate pyrolysis method has been studied. The techniques applied were: a.c. susceptibility at zero d.c. field, low field d.c. susceptibility, isothermal magnetization and a.c. susceptibility at varying bias fields up to 5 T. To investigate intragrain links, powders of known sizes were used directly, dispersed in oil and finally in the sintered form. Intragrain inductive critical currents and critical field values are derived. Finally, the experimental results are discussed within the framework of weak link models and flux pinning effects.

Rillo, C.; Lera, F.; Navarro, R.; Bartolomé, J.; Flokstra, J.; Blank, D. H. A.

352

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

353

Chem-Prep PZT 95/5 for Neutron Generator Applications: Powder Fractionation Study of Production-Scale Powders  

SciTech Connect

The Materials Chemistry Department 1846 has developed a lab-scale chem-prep process for the synthesis of PNZT 95/5, referred to as the ''SP'' process (Sandia Process). This process (TSP) has been successfully transferred to and scaled-up by Department 14192 (Ceramics and Glass Department), producing the larger quantities of PZT powder required to meet the future supply needs of Sandia for neutron generator production. The particle size distributions of TSP powders routinely have been found to contain a large particle size fraction that was absent in development (SP) powders. This SAND report documents experimental studies focused on characterizing these particles and assessing their potential impact on material performance. To characterize these larger particles, fractionation of several TSP powders was performed. The ''large particle size fractions'' obtained were characterized by particle size analysis, SEM, and ICP analysis and incorporated into compacts and sintered. Large particles were found to be very similar in structure and composition as the bulk of the powder. Studies showed that the large-size fractions of the powders behave similarly to the non-fractionated powder with respect to the types of microstructural features once sintered. Powders were also compared that were prepared using different post-synthesis processing (i.e. differences in precipitate drying). Results showed that these powders contained different amounts and sizes of porous inclusions when sintered. How this affects the functional performance of the PZT 95/5 material is the subject of future investigations.

MOORE, DIANA L.; VOIGT, JAMES A.; WATSON, CHAD S.; MCKENZIE, BONNIE B.; MOORE, ROGER H.; HUTCHINSON, MICHAEL A.; LOCKWOOD, STEVEN J.; RODMAN-GONZALES, EMILY D.

2003-06-01

354

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

355

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

356

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

357

Strengthening mechanisms of tungsten powder reinforced uranium  

SciTech Connect

Tungsten powder reinforced uranium exhibits a three-fold increase in yield strength due to precipitation hardening. The tungsten-rich interphase precipitates form at moving phase boundaries during slow cooling. Further increases in yield strength, attained with increasing tungsten content, are due to composite strengthening; this is verified by increasing elastic modulus with increasing tungsten content. Age hardening behavior is observed, with strengthening occurring at aging temperatures low in the alpha phase. Aging higher in alpha gives initial strengthening followed by rapid overaging. Beta phase aging results in a very soft structure with precipitates visible optically. Wrought material exhibits significant strain hardening as well as composite strengthening due to elongation of the tungsten particles. 7 refs., 15 figs., 4 tabs.

Lewis, M.A.K.; Hill, M.A.; Rollett, A.D.; Dunn, P.S.; Mortensen, A. (Los Alamos National Lab., NM (USA); Massachusetts Inst. of Tech., Cambridge, MA (USA))

1989-01-01

358

Powder and compaction characteristics of pregelatinized starches.  

PubMed

Pregelatinized starch is widely used as a pharmaceutical aid, especially as a filler-binder. It is known that the tableting performance of excipients could be affected by their source. The aim of this study was to evaluate the powder and tableting properties of pregelatinized starches obtained from yucca, corn and rice and compare those properties with those of Starch 1500. This material had the lowest particle size, and porosity and largest density and best flow. However, yucca starch and corn starch showed an irregular granule morphology, better compactibility and compressibility than Starch 1500. Their onset of plastic deformation and their strain rate sensitivity was comparable to that of Starch 1500. These two materials showed compact disintegration slower that Starch 1500. Conversely, rice starch showed a high elasticity, and friability, low compactibility, which are undesirable for direct compression. This study demonstrated the potential use of pregelatinized starches, especially those obtained from yucca and corn as direct compression filler-binders. PMID:22822539

Rojas, J; Uribe, Y; Zuluaga, A

2012-06-01

359

Process for preparing titanium nitride powder  

DOEpatents

A process for making titanium nitride powder by reaction of titanium phosphates with sodium cyanide. The process of this invention may comprise mixing one or more phosphates of Ti with a cyanide salt in the absence of oxygen and heating to a temperature sufficient to cause reaction to occur. In the preferred embodiment the ratio of cyanide salt to Ti should be at least 2 which results in the major Ti-containing product being TiN rather than sodium titanium phosphate byproducts. The process is an improvement over prior processes since the byproducts are water soluble salts of sodium which can easily be removed from the preferred TiN product by washing. 2 tabs.

Bamberger, C.E.

1988-06-17

360

Properties of HIPed stainless steel powder  

NASA Astrophysics Data System (ADS)

In the current design of ITER primary wall, 316LN stainless steel is the reference structural material. Austenitic stainless steel is used for water-cooling channels and structures. As material data on hot isostatic pressed (HIP) 316LN were not available in open literature and from powder producers, the main properties of unirradiated samples have been measured in CEA/CEREM. Fully dense material without any porosity is obtained when appropriate HIP parameters are applied. Microstructural examination and mechanical properties are confirmed that the HIPed 316LN material is equivalent to a very good fine-grain, isotropic and uniformly forged 316LN. Moreover, ultrasonic inspection showed that this fine and uniform microstructure produced a remarkably low noise, which allow the use of transverse waves at very high frequencies (4 MHz). Defects undetectable in forged material will be easily detected in HIPed material.

Dellis, Ch.; Le Marois, G.; Gentzbittel, J. M.; Robert, G.; Moret, F.

1996-10-01

361

Adsorption of arsenate on untreated dolomite powder.  

PubMed

Raw dolomite powder was evaluated for its efficiency in adsorbing As(V) from water. An experimental setup comprised of a fluidized dolomite powder bed was used to assess the impact of various test variables on the efficiency of removal of As(V). Test influents including distilled water (DW), synthetic groundwater (SGW) and filtered sewage effluent (FSE) were employed to assess the effect of influent parameters on the adsorption process and the quality of the effluent generated. Dolomite exhibited good As(V) removal levels for distilled water (>92%) and synthetic ground water (>84%) influents at all initial As(V) concentrations tested (0.055-0.600 ppm). Breakthrough of dolomite bed occurred after 45 bed volumes for DW and 20 bed volumes for SGW influents with complete breakthrough taking place at more than 300 bed volumes. As(V) removal from FSE influents was relatively unsuccessful as compared to the DW and SGW influents. Partial removal in the order of 32% from filtered sewage effluent at initial concentration of 0.6 mg/L started at 75 bed volumes and gradually stopped at 165 bed volumes. Varying degrees of As(V) adsorption capacities were observed by the different test influents employed, which indicate that the adsorption of As(V) is adversely affected by competing species, mainly sulfates and phosphates present in the influent. The adsorptive behavior of dolomite was described by fitting data generated from the study into the Langmuir and Freundlich isotherm models. Both models described well the adsorption of dolomite. The average isotherm adsorptive capacity was determined at 5.02 mug/g. Regeneration of the dolomite bed can be achieved with the use of caustic soda solution at a pH of 10.5. PMID:17399893

Ayoub, G M; Mehawej, M

2007-09-01

362

Erosion dynamics of powder snow avalanches - Observations  

NASA Astrophysics Data System (ADS)

Powder snow avalanches (PSA) entrain massive amounts of material from the underlying snow cover by erosion mechanisms that are not fully understood. Despite their inherent diversity, PSAs have recognizable flow features: they are fast, reaching velocity up to 80 m/s, they develop a tall, low density powder cloud and, at the same time, they can exert impact pressure with similar magnitudes of high density flow. In this talk, we report observations that underscore the interplay between entrainment and flow dynamics qualitatively shared by several PSAs at the Vallée de la Sionne test site in Switzerland. Measurements include time-histories of snow pack thickness with buried FMCW radar and time-histories of particle velocity using optical sensors, cloud density and cluster size using capacitance probes, and impact pressure measured at several elevations on a pylon. Measurements show that, at the avalanche front, a layer of light, cold and cohesionless snow is rapidly entrained, creating a turbulent and stratified head region with intermittent snow clusters. Fast and localized entrainment of deeper and warmer snow layers may also occur well behind the front, up to a distance of hundreds of meters, where pronounced stratification appears and snow clusters grow larger. In the avalanche head, impact pressure strongly fluctuates and is larger near the ground. Velocity profiles change throughout the avalanche head, with more abrupt changes localized where rapid entrainment occurs. A basal, continuous dense layer forms as deeper, warmer and denser snow cover is entrained and as suspended material starts to deposit. The thickness of the basal layer progressively increases toward the avalanche tail where, finally, deposition occurs en masse. Toward the avalanche tail, velocity profiles tend to become uniform, impact pressures are lower and nearly constant, while entrainment processes are negligible. These observations underscore the relevance of entrainment location and the nature of the erodible material on avalanche dynamics and contrast the sharply different behaviors observed at the head of PSAs and well behind it.

Sovilla, Betty; Louge, Michel

2013-04-01

363

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

364

Parametric studies of the hot isostatic pressing of rapidly solidified 304 stainless steel powder  

SciTech Connect

The increasing importance of powder materials fabrication by use of hot isostatic pressing (HIP) has led to recent emphasis on analytical techniques for describing and understanding the process. Understanding of particle consolidation during the HIP process has been attempted through the modeling of densification behavior by considering the deformation of a representative particle due to forces transmitted through the particle contacts. However, the properties of HIPed material have not been thoroughly investigated in terms of their deformation maps and HIP parameters. Mechanical properties of a compact can be quite different depending on the location of various deformation map boundaries. Diffusional creep is involved not only in densification but also in bonding at particle contacts. HIP pressure increases mechanical contact and enhances density but not particle bonding per se. Discrepancies between experimental and calculated data points for shorter HIP times may have been affected by oxide film layer on the original powder.

Kim, W.; Flinn, J.E.; Byrne, J.G. (Univ. of Utah, Salt Lake City, UT (United States). Dept. of Metallurgical Engineering)

1993-01-01

365

A double-helix neutron detector using micron-size 10B powder  

NASA Astrophysics Data System (ADS)

A double-helix electrode configuration is combined with a 10B powder coating technique to build large-area (9 in.×36 in., or about 23 cm by 91 cm) neutron detectors. The neutron detection efficiency for each of the four prototypes is comparable to 3.7×103 cm3 of 3He inside a cylindrical tube 91 cm long. One unit has been operational continuously for 18 months and the change of efficiency is less than 1%. An analytic model for pulse height spectra is described and the predicted mean film thicknesses agree with the experiment to within 30%. Further detector optimization is possible through film texture, powder size, moderator box and gas. The estimated production cost per unit is less than 3k US$ and the technology is thus suitable for deployment in large numbers.

Wang, Zhehui; Morris, C. L.; Bacon, J. D.; Brockwell, M. I.; Ramsey, J. C.

2014-11-01

366

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

367

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

368

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; Räty, Jarkko; Virtanen, Vesa

2010-11-01

369

Rayleigh-Taylor Instabilities in Thin Films of Tapped Powder  

Microsoft Academic Search

We observe powder ``droplets'' forming when tapping repeatedly a horizontal flat plate initially covered with a monolayer of fine powder particles. Starting from a simple model involving both the air flow through the porous cake and avalanche properties, we set up an analytical model which satisfactorily fits the experimental results. We observe a close analogy between the governing equations of

Jacques Duran; M. Curie

2001-01-01

370

Sinterable powders from laser driven reactions : final report  

E-print Network

Extremely fine, uniform ceramic powders have been synthesized from Sil4 NH3 and C2H4 gas phase reactants that are heated by absorbing optical energy emitted from a C02 laser. Resulting Si, Si3N4 and SiC powders have been ...

Haggerty, John Scarseth

1981-01-01

371

YBCO superconducting powder generation by an aerosol process  

SciTech Connect

Superconducting YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} (YBCO) powders were successfully generated by aerosol processes. Two effects of processing parameters on final superconducting-powder characteristics were investigated. The aerosol YBCO powders were characterized according to their oxygen stoichiometry, particle-size distribution, morphology, magnetization, transition temperature, and lattice-cell dimensions. These properties were examined using thermogravimetric analysis (TGA), X-ray diffraction, aerosol instruments, and a magnetometer. A series of aerosol YBCO powder-sintering experiments including oxygen loading and desorption were performed. Several quantitative relationships were determined from the results of X-ray diffraction, TGA, and magnetization measurements. Magnetization and Moessbauer spectrometry of the aerosol powders were conducted. Iron doping of aerosol YBCO powders led to a random replacement of Cu for Fe in the chain and planes of the host structure. A cascade impactor was used to classify the powders into different size regimes. Two length scales (penetration depth, and coherence length) characterizing superconductivity in aerosol YBCO powders were established for the first time from magnetization measurements.

Zhou Derong.

1991-01-01

372

Evaluation of reaction kinetics for gas-powder systems  

Microsoft Academic Search

Kinetic models for the reaction between a gas and powder are presented and discussed. Rates from the progressive conversion model are dependent on the amount of material present. This model is described by an equation that yields both the rate constant and the reaction order. The phase boundary model produces rates for topochemical reactions which are dependent on the powder

J. L. Stakebake; G. E. Bixby

1979-01-01

373

Recovery of Blood Group Antibodies from Erythrocyte Powder  

Microsoft Academic Search

IN A PREVIOUS PAPER,' experiments on the application of erythrocyte powder in serologic laboratories were described. It was shown that erythrocyte powder may be successfully used for (1) absorption of useless and disturbing antibodies from test sera, (2) complement fixation test with strong group antibodies, and (3) preparation of \\

FELIX MILGROM; CARLOS ORELLANA; MIGUEL LAYRISSE

1959-01-01

374

NOTES AND COMMENTS Revisiting powdered sugar for varroa control on  

E-print Network

.) Jennifer A Berry1 , Ohad Afik1,2 , Maxcy P Nolan IV1 and Keith S Delaplane1* 1 Department of Entomology) in Florida. These authors dusted the top bars of brood combs with powdered sugar every two weeks from April 3 days apart) or (b) treatment applied one day at an interval of every 2 weeks, and; 3. powdered

Delaplane, Keith S.

375

Investigation on pozzolanic effect of perlite powder in concrete  

Microsoft Academic Search

The pozzolanic effect of perlite powder (PP) added to concrete can be determined quantitatively with strength indices: specific strength ratio (R), index of specific strength (K), and contribution percentage of pozzolanic effect to strength (P). Besides compressive strength, these indices indicate that perlite powder has a high pozzolanic effect and is an active mineral admixture (MA) for concrete.

L.-H Yu; H Ou; L.-L Lee

2003-01-01

376

PHYSICS DEPARTMENT Heat Transport in Evacuated Perlite Powder  

E-print Network

PHYSICS DEPARTMENT Heat Transport in Evacuated Perlite Powder Insulations and Its TECHNISCHE UNIVERSITÃ?T MÃ?NCHEN #12;#12;Heat Transport in Evacuated Perlite Powder Insulations and Its) with expanded perlite has been used for cryogenic applications, especially the storage of liquid gases at temper

Gross, Rudolf

377

ELASTOMERIC COATING OF FILLER POWDERS BY SLURRY PRECIPITATION  

E-print Network

size distribution. Introduction Prior to the processing of energetic formulations, filler powders density and use of surfactants all affected the size distribution and the integrity of the molding powder with air pressure regulated at 60 psi. An on- line filter is provided to remove moisture and the oil

378

ORIGINAL PAPER Fast crystallization of lactose and milk powder  

E-print Network

of milk powder in a sorption box at different temperatures and water activities to assess and amorphous lactose in a sorption box (packed bed) ranged from several hours to a week (Jouppila et al. 1997ORIGINAL PAPER Fast crystallization of lactose and milk powder in fluidized bed dryer

Paris-Sud XI, Université de

379

Producing titanium powder by continuous vapor-phase reduction  

NASA Astrophysics Data System (ADS)

One of the goals of the U.S. Department of Energy’s Albany Research Center is to reduce the cost of titanium parts by developing a continuous titanium process. In this work, titanium powder was produced by feeding liquid TiCl4, with argon as a carrier gas, and magnesium wire into a shaft reactor at 1,000°C. The magnesium and TiCl4 vaporized and reacted to produce a mixture of titanium, MgCl2, and magnesium powder. Ti/Mg/MgCl2 powder was removed from the argon gas stream by an electrostatic precipitator, and the titanium powder was separated from the magnesium and MgCl2 by either vacuum distillation or leaching. Vacuum distillation produced sintered titanium powder with lower oxygen levels, but unacceptably high levels of magnesium and chlorine. Leached powder was spherical and free-flowing with low levels of magnesium and chlorine, but the oxygen content was no lower than 0.82%. The high oxygen content of the leached powder is caused by surface oxidation of the submicrometer titanium powder.

Hansen, Dennis A.; Gerdemann, Stephen J.

1998-11-01

380

Selective laser melting of iron-based powder  

Microsoft Academic Search

Selective laser melting (SLM) is driven by the need to process near full density objects with mechanical properties comparable to those of bulk materials. During the process the powder particles are completely molten by the laser beam. The resulting high density allows avoiding lengthy post-processing as required with selective laser sintering (SLS) of metal powders. Unlike SLS, SLM is more

J. P. Kruth; L. Froyen; J. Van Vaerenbergh; P. Mercelis; M. Rombouts; B. Lauwers

2004-01-01

381

Dispersing WC–Co powders in aqueous media with polyethylenimine  

Microsoft Academic Search

The use of aqueous WC–Co suspensions for powder metallurgical processing of hard metal powders is expected to have environmental as well as economic advantages over the currently used systems with organic solvents. Without a suitable dispersing agent, however, poor mixing and aggregation of the different particulate constituents will occur in water and requirements on homogeneity and colloidal stability of the

Eric Laarz; Lennart Bergström

2000-01-01

382

Application of superalloy powder metallurgy for aircraft engines  

NASA Technical Reports Server (NTRS)

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

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

1980-01-01

383

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

384

Temperature distribution in powder beds during 3D printing  

Microsoft Academic Search

Purpose – This purpose of this paper is to report about the temperature distribution in metal and ceramic powder beds during 3D printing. The differing powders are thoroughly characterized in terms of thermal conductivity, thermal diffusivity, emissivity spectra and density. Design\\/methodology\\/approach – The temperature distribution was measured in a 3D printing appliance (Prometal R1) with the help of thin thermocouples

M. Dressler; M. Röllig; M. Schmidt; A. Maturilli; J. Helbert

2010-01-01

385

Coefficient of external friction in the pressing of metal powders  

Microsoft Academic Search

Experimental data on the external friction in the pressing of copper and iron powders have been processed graphicoanalytically, using Deryagin's binomial law, and the mechanical and adhesional components of the coefficients of friction in the pressing of these powders have been determined. A rise in pressing pressure decreases the static coefficient of friction by reducing its adhesional component.

N. A. Chainikov

1979-01-01

386

Numerical simulation of cohesive powder behavior in a fluidized bed  

Microsoft Academic Search

A numerical simulation model was developed for wet powder fluidization in the scope of investigation on cohesive powder behavior. The model was developed based on the discrete element method (DEM) with the inter-particle cohesive interaction due to liquid bridging. To take into account the liquid bridge force between particles and between a particle and a wall, a regression expression for

Takafumi Mikami; Hidehiro Kamiya; Masayuki Horio

1998-01-01

387

FINITE ELEMENT ANALYSIS OF CAPPING MECHANISMS DURING PHARMACEUTICAL POWDER COMPACTION  

E-print Network

Institute for Pharmaceutical Materials Science, Department of Materials Science and Metallurgy, UniversityFINITE ELEMENT ANALYSIS OF CAPPING MECHANISMS DURING PHARMACEUTICAL POWDER COMPACTION Chuan-Yu. Wu1 In this paper, the compaction of lactose powder, a typical pharmaceutical excipient, is modelled using finite

de Gispert, Adrià

388

Numerical Simulation on Pharmaceutical Powder Compaction Lianghao Han1,a  

E-print Network

Numerical Simulation on Pharmaceutical Powder Compaction Lianghao Han1,a , James Elliott1,b Department of Materials Science and Metallurgy, University of Cambridge, CB2 3QZ,UK 2 Pfizer Global R elasticity law developed to describe the compaction behavior of pharmaceutical powders. The model

Elliott, James

389

Ribbonizing of electrostatic powder spray impregnated thermoplastic tows by pultrusion  

Microsoft Academic Search

Process models have been developed for thermoset pultrusion and thermoplastic pultrusion using melt impregnated prepregs. Thermoplastic towpregs are manufactured using new innovative methods such as those using dry powder impregnation. The morphology of dry powder impregnated ‘towpregs’ consists of a dry fibre bundle surrounded by a layer of polymer. In this study a two-dimensional finite element model using non-Newtonian fluid

Narasinha C. Parasnis; Karthik Ramani; Harshad M. Borgaonkar

1996-01-01

390

Barium strontium titanate powder obtained by polymeric precursor method  

SciTech Connect

Pure barium strontium titanate powder, with Ba/Sr ratio of 80/20 was prepared by the polymeric precursor method (also called Pechini process). The powder was obtained after a calcination at 800 deg. C for 8 h and characterized by XRD, IR, BET and SEM. The requirements to avoid barium carbonate as a secondary phase are presented and discussed in detail.

Ries, A.; Simoes, A.Z.; Cilense, M.; Zaghete, M.A.; Varela, J.A

2003-03-15

391

Synthesis and spectral characterizations of Fe3+ doped ?-BaB2O4 nano crystallite powder  

NASA Astrophysics Data System (ADS)

Fe3+ doped ?-BaB2O4 nano crystallite powder is synthesized and characterized by spectroscopic techniques. From the Powder X-ray diffraction data, Fe3+ doped ?-BBO material is observed to be monoclinic. Its average crystallite size is evaluated about 75 nm. The particle-like morphology has been observed from SEM images. The EPR spectrum shows two resonance signals at g = 4.23 and g = 2.07, respectively which are indicative of Fe3+ ions in tetragonally distorted octahedral site symmetry. Crystal field parameter (Dq) and Racah parameters (B and C) are evaluated. Fe3+ doped ?-BaB2O4 nano crystallite powder luminescence properties have been studied. The emission of ?-BaB2O4:Fe3+ sample is exhibited two main peaks at 419 and 443 nm. FT-IR spectrum shows the characteristic vibrations of host lattice.

Venkata Reddy, Ch.; Rama Krishna, Ch.; Raghavendra Rao, T.; Udayachandran Thampy, U. S.; Reddy, Y. P.; Rao, P. S.; Ravikumar, R. V. S. S. N.

2012-03-01

392

Production and properties of flat ceramic microfiltration membranes made of {alpha}-Al{sub 2}O{sub 3} powders  

SciTech Connect

Ceramic membranes are widely used to purify, separate, fractionate, and concentrate aggressive solutions and mixtures of components of different compositions and chemistry. Microfiltration membranes can be obtained by different methods in ceramics technology and powder metallurgy by varying the forming technique (pressing of powders, slip casting, etc.), the dispersity of the initial components, and production conditions. When relatively large flat ceramic microfiltration membranes are being made, it is difficult to attain a high porosity with a narrow pore-size distribution and achieve good permeability along with satisfactory mechanical properties. We have developed a technology for producing such membranes by using dispersed powders of aluminum oxide. Different forming methods are used in the process.

Bryk, M.T.; Volkova, A.P.; Klimenko, A.V. [Institute of Colloid and Water Chemistry, Kiev (Ukraine)]|[Institute of Problems of Materials Science, Kiev (Ukraine)] [and others

1995-03-01

393

An investigation of adhesive/adherend and fiber/matrix interactions. Part A: Surface characterization of titanium dioxide, titantium and titanium 6% Al to 4% V powders: Interaction with water, hydrogen chloride and polymers  

NASA Technical Reports Server (NTRS)

The titanium dioxide surface is discussed. Polymer adhesive are also discussed. Titanium powders are considered. Characterization techniques are also considered. Interactions with polymers, water vapor, and HCl are reported. Adsorbents are characterized.

Siriwardane, R. V.; Wightman, J. P.

1982-01-01

394

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

395

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

396

Growth and characterization of L-serine formate nonlinear optical single crystal  

NASA Astrophysics Data System (ADS)

A novel organic nonlinear optical single crystal L-Serine Formate (LSF) was successfully grown by solution growth using the slow evaporation technique. The structure of the grown crystal has been determined by single crystal X-ray diffraction analysis. The presence of functional groups in LSF crystal has been identified by FTIR spectrum. The crystal is transparent over entire visible region. The second harmonic generation efficiency of the grown LSF crystal has been obtained by the Kurtz-Perry powder technique. The laser induced surface damage threshold value 6.836 GW/cm2 indicates that this material can be used for high-power laser applications.

Krishnan, P.; Gayathri, K.; Anbalagan, G.

2013-02-01

397

30 CFR 75.1101-13 - Dry powder chemical systems; general.  

... 2014-07-01 false Dry powder chemical systems; general. 75.1101-13...Protection § 75.1101-13 Dry powder chemical systems; general. Self-contained dry powder chemical systems may be installed to protect...

2014-07-01

398

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

...2014-07-01 false Installation of dry powder chemical systems. 75.1101-14 Section 75...1101-14 Installation of dry powder chemical systems. (a) Self-contained dry powder chemical systems shall be installed to...

2014-07-01

399

30 CFR 75.1101-22 - Inspection of dry powder chemical systems.  

...2014-07-01 false Inspection of dry powder chemical systems. 75.1101-22 Section 75...75.1101-22 Inspection of dry powder chemical systems. (a) Each dry powder chemical system shall be examined weekly and a...

2014-07-01

400

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 Å-1powder diffraction. IPD covers d range 0.15

Kamiyama, T.

2008-03-01

401

Powder metallurgy process for manufacturing core projectile  

NASA Astrophysics Data System (ADS)

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

Akbar, Taufik; Setyowati, Vuri Ayu; Widyastuti

2013-09-01

402

Nondestructive Evaluation of Reactive Powder Concrete  

NASA Astrophysics Data System (ADS)

Reactive powder concrete (RPC) has been introduced as a structural material for civil engineering applications. The material consists of a finely graded combination of cement, sand, ground quartz and silica fume which combined with water form a cement paste. Small steel fibers measuring approximately 0.2 mm in diameter and 12 mm in length are distributed throughout the cement matrix and the combined material has very high compressive strength and toughness. The material is proposed for use in the primary load bearing members in bridges, and as such nondestructive evaluation technologies are needed to evaluate material quality and monitor in-service condition. This paper reports on research to determine the effectiveness of ultrasonic testing for determining the elastic properties of RPC. Comparison between static modulus of elasticity and ultrasonic modulus measurements is presented. A system for determining elastic moduli as a quality control tool is discussed. The effect of curing conditions on ultrasonic velocities and resulting calculated moduli values is presented and compared with traditional measurement methods.

Washer, Glenn; Fuchs, Paul; Graybeal, Benjamin; Rezaizadeh, Ali

2004-02-01

403

Tritium cleanup on hot uranium powder  

SciTech Connect

20 g of uranium powder was used in laboratory setup at temperatures between 500 and 900/sup 0/C to study the retention of 1% each of O/sub 2/, N/sub 2/, NH/sub 3/, CO/sub 2/, and CH/sub 4/ either as single impurities or three-component mixtures in H/sub 2/ . O/sub 2/, NH/sub 3/, and N/sub 2/ as single impurities can be retained down to residual concentrations of 1 to 20 ppm at 500/sup 0/C. This is also true of CO/sub 2/, but a large volume of CH/sub 4/ is produced in this case. CH/sub 4/ as a single impurity is not retained effectively below 900/sup 0/C. O/sub 2/ redecomposes the uranium nitrides and carbides already formed. The achievable degrees of conversion are between 10% and 100% for the reactions and increase as the temperature is raised.

Schira, P.; Hutter, E.

1988-09-01

404

Device for preparing combinatorial libraries in powder metallurgy.  

PubMed

This paper describes a powder-metering, -mixing, and -dispensing mechanism that can be used as a method for producing large numbers of samples for metallurgical evaluation or electrical or mechanical testing from multicomponent metal and cermet powder systems. It is designed to make use of the same commercial powders that are used in powder metallurgy and, therefore, to produce samples that are faithful to the microstructure of finished products. The particle assemblies produced by the device could be consolidated by die pressing, isostatic pressing, laser sintering, or direct melting. The powder metering valve provides both on/off and flow rate control of dry powders in open capillaries using acoustic vibration. The valve is simple and involves no relative movement, avoiding seizure with fine powders. An orchestra of such valves can be arranged on a building platform to prepare multicomponent combinatorial libraries. As with many combinatorial devices, identification and evaluation of sources of mixing error as a function of sample size is mandatory. Such an analysis is presented. PMID:15244416

Yang, Shoufeng; Evans, Julian R G

2004-01-01

405

Effects of humidity on the magnetic and woody characteristics of powder-type magnetic wood  

NASA Astrophysics Data System (ADS)

Among three types of proposed magnetic wood, powder-type magnetic wood can be made of recycled magnetic materials from IT devices, consumer electronics and waste wood. Because of its wood powder content, powder-type magnetic wood shows special characteristics different from those of typical magnetic materials. We focused on the relationship between humidity and magnetic characteristics of powder-type magnetic wood. The magnetic powder ratio, wood powder density and magnetic binder density were all examined as parameters for AC permeability.

Oka, H.; Tokuta, H.; Namizaki, Y.; Sekino, N.

2004-05-01

406

Pellet fabrication development using thermally denitrated UO sub 2 powder  

SciTech Connect

Pacific Northwest Laboratory (PNL) has evaluted, on a laboratory scale, the characteristics and pellet fabrication properties of UO{sub 3} powder prepared by the thermal denitration process. Excellent quality, 96% TD (percent of theoretical density) pellets were produced from development lots of this powder. Apparently, the key to making this highly sinterable powder from uranyl nitrate is the addition of ammonium nitrate (NH{sub 4}NO{sub 3}) to the feed solution prior to thermal denitration. Powder lots were processed with and without the NH{sub 4}NO{sub 3} addition in the feed solution. The lots included samples from the ORNL laboratory rotary kiln and from a larger scale rotary kiln at National Lead of Ohio (NLO). In the PNL evaluation, samples of UO{sub 3} were calculated and reduced to UO{sub 2}, followed by conventional process procedures to compare the sinterability of the powder lots. The high density pellets made from the powder lots, which included the NH{sub 4}NO{sub 3} addition, were reduced to Fast Breeder Reactor (FBR) density range of 88 to 92% TD by the use of poreformers. The NH{sub 4}NO{sub 3} addition also improved the sinterability properties of uranium oxide powders that contain thorium and cerium. Thorium and cerium were used as stand-in'' for plutonium used in urania-plutonia FBR fuel pellets. A very preliminary examination of a single lot of thermally denitrated uranium-plutonium oxide powder was made. This powder lot was made with the NH{sub 3}NO{sub 3} addition and produced pellets just above the FBR density range.

Davis, N.C.; Griffin, C.W.

1992-05-01

407

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

408

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

409

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

410

Application of powder X-ray diffraction in studying the compaction behavior of bulk pharmaceutical powders.  

PubMed

This study investigates the effects of crystal lattice deformation on the powder X-ray diffraction (PXRD) patterns of compressed polycrystalline specimen (compacts/tablets) made from molecular, crystalline powders. The displacement of molecules and the corresponding adjustment of interplanar distances (d-spacings) between diffracting planes of PNU-288034 and PNU-177553, which have crystal habits with a high aspect ratio favoring preferred orientation during tableting, are demonstrated by shifts in the diffracted peak positions. The direction of shift in diffracted peak positions suggests a reduction of interplanar d-spacing in the crystals of PNU-288034 and PNU-177553 following compaction. There is also a general reduction of peak intensities following compression at the different compressive loads. The lattice strain representing the reduction in d-spacing is proportional to the original d-spacing of the uncompressed sample suggesting that, as with systems that obey a simple Hooke's law relationship, the further apart the planes of atoms/molecules within the lattice are, the easier it is for them to approach each other under compressive stresses. For a third model compound comprising more equant-shaped crystals of PNU-141659, the shift in diffracted peak positions are consistent with an expansion of lattice spacing after compression. This apparent anomaly is supported by the PXRD studies of the bulk powder consisting of fractured crystals where also, the shift in peak position suggests expansion of the lattice planes. Thus the crystals of PNU-141659 may be fracturing under the compressive loads used to produce the compacts. Additional studies are underway to relate the PXRD observations with the bulk tableting properties of these model compounds. PMID:16200547

Bandyopadhyay, Rebanta; Selbo, Jon; Amidon, Gregory E; Hawley, Michael

2005-11-01

411

Implications of elastic wave velocities for Apollo 17 rock powders  

NASA Technical Reports Server (NTRS)

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

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

1974-01-01

412

The rheology and hydrodynamics of dry powder lubrication  

NASA Technical Reports Server (NTRS)

This paper conceptualizes a powder lubrication mechanisms which closely resembles that of a hydrodynamic fluid film. Based on the observations of past investigations and on the author's experiments, it is postulated that a layered shearing of the compacted powder generates velocity, density, and temperature profiles akin to fluid film bearings. Thus, a lubricant consisting of a fine powder unserted either deliberately or one generated by the water of the mating surfaces, constitutes a viable lubricant that generates the required flows and pressures to prevent contact between the surfaces.

Heshmat, Hooshang

1991-01-01

413

Acetone Powder From Dormant Seeds of Ricinus communis L  

NASA Astrophysics Data System (ADS)

The influence of several factors on the hydrolytic activity of lipase, present in the acetone powder from dormant castor seeds (Ricinus communis) was evaluated. The enzyme showed a marked specificity for short-chain substrates. The best reaction conditions were an acid medium, Triton X-100 as the emulsifying agent and a temperature of 30°C. The lipase activity of the acetone powder of different castor oil genotypes showed great variability and storage stability of up to 90%. The toxicology analysis of the acetone powder from genotype Nordestina BRS 149 showed a higher ricin (toxic component) content, a lower 2S albumin (allergenic compound) content, and similar allergenic potential compared with untreated seeds.

Cavalcanti, Elisa D. C.; Maciel, Fábio M.; Villeneuve, Pierre; Lago, Regina C. A.; Machado, Olga L. T.; Freire, Denise M. G.

414

Simulation Study for Complex Shaped Pressing of Ceramic Powder  

NASA Astrophysics Data System (ADS)

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

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

2010-07-01

415

Atomizing apparatus for making polymer and metal powders and whiskers  

DOEpatents

Method for making polymer particulates, such as spherical powder and whiskers, by melting a polymer material under conditions to avoid thermal degradation of the polymer material, atomizing the melt using gas jet means in a manner to form atomized droplets, and cooling the droplets to form polymer particulates, which are collected for further processing. Atomization parameters can be controlled to produce polymer particulates with controlled particle shape, particle size, and particle size distribution. For example, atomization parameters can be controlled to produce spherical polymer powders, polymer whiskers, and combinations of spherical powders and whiskers. Atomizing apparatus also is provided for atoomizing polymer and metallic materials.

Otaigbe, Joshua U. (Ames, IA); McAvoy, Jon M. (Moline, IL); Anderson, Iver E. (Ames, IA); Ting, Jason (Ames, IA); Mi, Jia (Pittsburgh, PA); Terpstra, Robert (Ames, IA)

2003-03-18

416

Sintering densification for powder mixtures of varying distribution widths  

SciTech Connect

A model for the sintering of bimodal powders is used to evaluate densification results for log-normal particle size distributions involving a constant median size on a weight basis. The model predicts a minimum in densification for distributions of intermediate width when the green density is held constant. This has been observed experimentally for sintered tungsten powders. As a consequence, wide particle size distributions are attractive for high packing and sintering densities, indicating possible new feedstock formulations for shaping technologies such as powder injection molding and slip casting. 10 refs.

German, R.M. (Pennsylvania State University, University Park (United States))

1992-09-01

417

Properties of powder-impregnated graphite/PEKK  

NASA Technical Reports Server (NTRS)

Poly Ether Ketone Ketone (PEKK) powders were prepregged on AS4 (12K), IM7 (12K), and G30-500 (12K) carbon fibers and consolidated into unidirectional laminates. The preferred formulation of PEKK for the dry powder process was identified. Mechanical test data on panels prepared via the powder process agreed well with flex, short beam shear, and double cantilever beam values obtained previously on melt-impregnated material. IM7/PEKK composites showed superior mechanical properties to AS4/PEKK and G30-500/PEKK composites. Transverse flexural strength and fiber/resin contact angle correlated well as measures of the fiber/matrix interfacial strength.

Bucher, R. A.; Hinkley, J. A.

1992-01-01

418

High T sub c superconductor coating on metal substrates by an electrophoretic technique  

Microsoft Academic Search

This paper reports high-{Tc} superconductor wire and sheet fabricated by electrophoretic deposition of superconductor powders on silver-metal substrates followed by an appropriate sintering schedule. The technique has some promise for technological applications.

H. S. Maiti; S. Datta; R. N. Basu

1989-01-01

419

Polyaniline films and powders: Effect of excess dopant acid on conductivity  

SciTech Connect

We have shown previously that excess dopant acid, d,l camphorsulfonic acid, (HCSA), when present in a solution of m-cresol containing polyaniline doped with HCSA, reduces the conductivity of films of the doped polyaniline cast from the solution. We here report that the opposite effect is observed with powders of the same doped polyaniline. Polyaniline doped with HCSA was precipitated by pouring a solution of the doped polyaniline into excess hexane; it was then washed with either methanol or methanol containing HCSA to remove the m-cresol. The quantity of HCSA in the resulting dried powders was determined using TGA techniques. It was found that excess HCSA in the doped polyaniline increased the conductivity of compressed pellets of the polymer. The conductivity was increased from {approximately}4 S/cm (no excess HCSA) to {approximately}40 S/cm in material containing twice the amount of HCSA necessary for doping. The conductivity of {approximately}40 S/cm is the highest yet reported for doped polyaniline powders. Reasons for this increase conductivity will be presented.

Feng, J.; MacDiarmid, A.G. [Univ. of Pennsylvania, Philadelphia, PA (United States)

1995-12-31

420

Evolution of the internal dynamics of two globular proteins from dry powder to solution.  

PubMed Central

Myoglobin and lysozyme picosecond internal dynamics in solution is compared to that in hydrated powders by quasielastic incoherent neutron scattering. This technique is sensitive to the motions of the nonexchangeable hydrogen atoms in a sample. Because these are homogeneously distributed throughout the protein structure, the average dynamics of the protein is described. We first propose an original data treatment to deal with the protein global motions in the case of solution samples. The validity of this treatment is checked by comparison with classical measurements of the diffusion constants. The evolution with the scattering vector of the width and relative contribution of the quasielastic component was then used to derive information on the amount of local diffusive motions and their characteristic average relaxation time. From dry powder to coverage by one water layer, the surface side chains progressively acquire the possibility to diffuse locally. On subsequent hydration, the main effect of water is to improve the rate of these diffusive motions. Motions with higher average amplitude occur in solution, about three times more than for a hydrated powder at complete coverage, with a shorter average relaxation time, approximately 4.5 ps compared to 9.4 ps for one water monolayer. PMID:10388771

Perez, J; Zanotti, J M; Durand, D

1999-01-01

421

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

422

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?µm. 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?°C. A slight increase in higher molecular weight aggregates was found in formulations containing the polymer dextran after 12 months of storage at 50?°C. Light obscuration measurements showed an increase in cumulative particle counts after cryo-milling that did not further increase during storage at 2-8?°C 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

423

Arbitrary Lagrangian Eulerian method in plasticity of pressure-sensitive material: application to powder forming processes  

NASA Astrophysics Data System (ADS)

In this paper, an application of Arbitrary Lagrangian Eulerian (ALE) method is presented in plasticity behavior of pressure-sensitive material, with special reference to large deformation analysis of powder compaction process. In ALE technique, the reference configuration is used for describing the motion, instead of material configuration in Lagrangian, and spatial configuration in Eulerian formulation. The convective term is used to reflect the relative motion between the mesh and the material. Each time-step is divided into the Lagrangian phase and Eulerian phase. The convection term is neglected in the material phase, which is identical to a time-step in a standard Lagrangian analysis. The stresses and plastic internal variables are converted to account the relative mesh-material motion in the convection phase. The ALE formulation is then performed within the framework of a three-invariant cap plasticity model in order to predict the non-uniform density distribution during the large deformation of powder die pressing. The plasticity model is based on a hardening rule with the isotropic and kinematic material functions. The constitutive elasto-plastic matrix and its components are derived by using the definition of yield surface, material functions and non-linear elastic behavior, as function of hardening parameters. Finally, the numerical examples are performed to illustrate the applicability of the computational algorithm in modeling of powder forming process and the results are compared with those obtained from Lagrangian simulation in order to demonstrate the accuracy of proposed model.

Khoei, A. R.; Anahid, M.; Shahim, K.; Dormohammadi, H.

2008-04-01

424

The effect of deposition parameters on the morphology of micron diamond powders synthesized by HFCVD method  

NASA Astrophysics Data System (ADS)

The micron well-faceted diamond powders have attracted an increasing attention in the polishing filed, owing to improve the surface finish of components using the powders. In the present work, the hot filament chemical vapor deposition (HFCVD) technique is employed for synthesizing such diamond powders. A great many of micron diamonds are grown simultaneously but independently onto a large-area substrate. First, a novel seeding method, spraying the diamond seeds suspension toward the substrate using a spin coater machine, is proposed, with which the seeds with a controlled density are distributed evenly onto the substrate. Also, the method is more suitable for the fabrication of the micron isolated diamonds, compared with other nucleation initiation methods, such as the scratching pre-treatment and electrical biasing on substrates. Afterwards, a systematic investigation is under taken into the effects of deposition parameters on the basic growth characteristics of CVD micron diamonds, and on the inhibition of films growth. Furthermore, the reactive pressure, substrate temperature, carbon concentration, and growth duration are determined to be 4500 Pa, 850 °C, 1.3-1.4%, 60-90 min, respectively. Eventually, under the preferred deposition conditions, approximately 15 million cube-octahedral crystals with the mean size of 2-3 ?m are deposited simultaneously on the 1000 mm2 substrate.

Zhang, Tao; Wang, Xinchang; Shen, Bin; Sun, Fanghong; Zhang, Zhiming

2013-06-01

425

Characterization of nanophase Al-oxide/Al powders by electron energy-loss spectroscopy.  

PubMed

Al nanoparticles were prepared by the inert gas condensation method. After passivation with oxygen and air exposure we obtained a powdered sample of an Al-oxide/Al nanocomposite material. In the present paper we describe the use of the electron energy-loss spectroscopy (EELS) technique in a transmission electron microscope to characterize such nanostructured powders compared with a microcrystalline commercial aluminium foil. Energy-filtered images showed the presence of an alumina overlayer of approximately 4 nm covering the aluminium nanoparticles (23 nm in diameter). EELS analysis enabled us to determine the total amount of Al2O3 and metallic Al and the structure of the alumina passivation overlayer in the sample. In particular, the extended energy-loss fine structure analysis of the data showed a major presence of Al tetrahedrally coordinated with oxygen in the alumina passivation layer of Al nanoparticles instead of the octahedral coordination found for a conventional Al foil. This surprising effect has been attributed to the nanoscopic character of the grains. The analysis of the electron-loss near-edge structure also determines the presence of a certain degree of aggregation in this kind of powdered sample as result of the coalescence of the nanocrystalline grains. The procedure presented here may have the potential to solve other problems during characterization of nanostructured materials. PMID:9767485

Fernández; Sánchez-López; Caballero; Martin; Vacher; Ponsonnet

1998-08-01

426

Dissolution properties of piroxicam powders and capsules as a function of particle size and the agglomeration of powders.  

PubMed

The poor dissolution characteristics of relatively insoluble drugs have long been a problem to the pharmaceutical industry. An example is piroxicam, a highly potent anti-inflammatory agent. In many countries, a large number of generic piroxicam products are available to the prescriber. The aim of this study was to investigate the cause of the dissolution problems experienced by manufacturers of generic piroxicam capsules. Two raw material batches and the dissolution properties of several piroxicam capsules were studied. Differential scanning calorimetry (DSC) and X-ray powder diffraction (XRPD) results showed that the two raw material samples were identical with respect to polymorphic modification. The particles of powder 1 were smaller than those of powder 2, but the dissolution of powder 1 was much slower than that of powder 2. The dissolution results for the capsules showed a marked difference among different brands, with capsule C not meeting the USP tolerance. Adding surfactant to the dissolution medium increased the dissolution of both powder 1 and capsule C. Failure of powder 1 or capsule C to meet USP dissolution criteria could result in differences in product efficacy, as well as in potential side effects. Such observations should be taken into account along with other relevant considerations when decisions regarding the generic substitution of oral piroxicam products are made. PMID:11028221

Swanepoel, E; Liebenberg, W; de Villiers, M M; Dekker, T G

2000-10-01

427

Structural study of Al-1. 4 at pct Fe powder produced by atomization  

SciTech Connect

The Al[sub 1-x]Fe[sub x] alloys with small Fe content which have been studied in the past decades were mainly obtained by rapid solidification. These techniques noticeably increase the solubility of iron solute in the f.c.c. aluminium matrix, thereby reducing the formation of intermetallic compounds: depending on the quenching rate, the iron atoms may associate into clusters. It follows that the solid solution structure may look different from an ideally disordered one. For low rates of solidification, intermetallic compounds are formed and they modify the workability and chemical properties of the material. The small angle X-ray scattering technique would appear to be the most suitable to study the Fe dispersion. However, it seems that the electronic density of the obtained species is very close to that of Al so that no recent developments over the last years have been performed on this subject by that technique. Moessbauer Spectroscopy has not been extensively used to specify the various expected entities. An analysis of the microstructure of atomized powder has been carried out by electronic microscopy for an Al-4 at Pct Fe composition with powder particle size in the range lower than 50 [mu]m. Even if the structures were carefully studied versus the particle diameter, no information was elicited about the Fe distribution in the Al matrix. In the present work, results are given from X-ray diffraction, X-ray photoelectron spectrometry and Moessbauer Spectroscopy about the various iron combinations found in an Al-1.4 at Pct Fe powder prepared by atomization in air from the liquid alloy.

Djega-Meriadassou, C.; Chekroud, S.; Cizeron, G. (Univ. Paris Sud, Orsay (France))

1993-08-15

428

Absolute quantum yield measurement of powder samples.  

PubMed

Measurement of fluorescence quantum yield has become an important tool in the search for new solutions in the development, evaluation, quality control and research of illumination, AV equipment, organic EL material, films, filters and fluorescent probes for bio-industry. Quantum yield is calculated as the ratio of the number of photons absorbed, to the number of photons emitted by a material. The higher the quantum yield, the better the efficiency of the fluorescent material. For the measurements featured in this video, we will use the Hitachi F-7000 fluorescence spectrophotometer equipped with the Quantum Yield measuring accessory and Report Generator program. All the information provided applies to this system. Measurement of quantum yield in powder samples is performed following these steps: 1. Generation of instrument correction factors for the excitation and emission monochromators. This is an important requirement for the correct measurement of quantum yield. It has been performed in advance for the full measurement range of the instrument and will not be shown in this video due to time limitations. 2. Measurement of integrating sphere correction factors. The purpose of this step is to take into consideration reflectivity characteristics of the integrating sphere used for the measurements. 3. Reference and Sample measurement using direct excitation and indirect excitation. 4. Quantum Yield calculation using Direct and Indirect excitation. Direct excitation is when the sample is facing directly the excitation beam, which would be the normal measurement setup. However, because we use an integrating sphere, a portion of the emitted photons resulting from the sample fluorescence are reflected by the integrating sphere and will re-excite the sample, so we need to take into consideration indirect excitation. This is accomplished by measuring the sample placed in the port facing the emission monochromator, calculating indirect quantum yield and correcting the direct quantum yield calculation. 5. Corrected quantum yield calculation. 6. Chromaticity coordinates calculation using Report Generator program. The Hitachi F-7000 Quantum Yield Measurement System offer advantages for this application, as follows: High sensitivity (S/N ratio 800 or better RMS). Signal is the Raman band of water measured under the following conditions: Ex wavelength 350 nm, band pass Ex and Em 5 nm, response 2 sec), noise is measured at the maximum of the Raman peak. High sensitivity allows measurement of samples even with low quantum yield. Using this system we have measured quantum yields as low as 0.1 for a sample of salicylic acid and as high as 0.8 for a sample of magnesium tungstate. Highly accurate measurement with a dynamic range of 6 orders of magnitude allows for measurements of both sharp scattering peaks with high intensity, as well as broad fluorescence peaks of low intensity under the same conditions. High measuring throughput and reduced light exposure to the sample, due to a high scanning speed of up to 60,000 nm/minute and automatic shutter function. Measurement of quantum yield over a wide wavelength range from 240 to 800 nm. Accurate quantum yield measurements are the result of collecting instrument spectral response and integrating sphere correction factors before measuring the sample. Large selection of calculated parameters provided by dedicated and easy to use software. During this video we will measure sodium salicylate in powder form which is known to have a quantum yield value of 0.4 to 0.5. PMID:22617474

Moreno, Luis A

2012-01-01

429

Synthesis and Characterization of Oxide Feedstock Powders for the Fuel Cycle R&D Program  

SciTech Connect

Nuclear fuel feedstock properties, such as physical, chemical, and isotopic characteristics, have a significant impact on the fuel fabrication process and, by extension, the in-reactor fuel performance. This has been demonstrated through studies with UO{sub 2} spanning greater than 50 years. The Fuel Cycle R&D Program with The Department of Energy Office of Nuclear Energy has initiated an effort to develop a better understanding of the relationships between oxide feedstock, fresh fuel properties, and in-reactor fuel performance for advanced mixed oxide compositions. Powder conditioning studies to enable the use of less than ideal powders for ceramic fuel pellet processing are ongoing at Los Alamos National Laboratory (LANL) and an understanding of methods to increase the green density and homogeneity of pressed pellets has been gained for certain powders. Furthermore, Oak Ridge National Laboratory (ORNL) is developing methods for the co-conversion of mixed oxides along with techniques to analyze the degree of mixing. Experience with the fabrication of fuel pellets using co-synthesized multi-constituent materials is limited. In instances where atomically mixed solid solutions of two or more species are needed, traditional ceramic processing methods have been employed. Solution-based processes may be considered viable synthesis options, including co-precipitation (AUPuC), direct precipitation, direct-conversion (Modified Direct Denitration or MDD) and internal/external gelation (sol-gel). Each of these techniques has various advantages and disadvantages. The Fiscal Year 2010 feedstock development work at ORNL focused on the synthesis and characterization of one batch of UO{sub x} and one batch of U{sub 80}Ce{sub 20}O{sub x}. Oxide material synthesized at ORNL is being shipped to LANL for fuel fabrication process development studies. The feedstock preparation was performed using the MDD process which utilizes a rotary kiln to continuously thermally denitrate double salts of ammonium and metals to produce free-flowing powders that have good ceramic properties for fuel fabrication. Feedstock powder properties of interest include: particle size and distribution, surface area, phase purity, morphology, tap and bulk density, and flow characteristics.

Voit, Stewart L [ORNL; Vedder, Raymond James [ORNL; Johnson, Jared A [ORNL

2010-09-01

430

Al-doped Ni-rich cathode powders prepared from the precursor powders with fine size and spherical shape  

Microsoft Academic Search

LiNi0.8Co0.15Al0.05O2 cathode powders with fine size and spherical shape were prepared by solid-state reaction method using the Ni–Co–Al–O precursor powders with fine size and spherical shape. The Ni–Co–Al–O precursor powders with fine size and filled inner structure were prepared by spray pyrolysis from the spray solution with drying control chemical additive (DCCA), citric acid and ethylene glycol. The one LiNi0.8Co0.15Al0.05O2

S. H. Ju; H. C. Jang; Y. C. Kang

2007-01-01

431

Environmentally stable reactive alloy powders and method of making same  

DOEpatents

Apparatus and method for making powder from a metallic melt by atomizing the melt to form droplets and reacting the droplets downstream of the atomizing location with a reactive gas. The droplets are reacted with the gas at a temperature where a solidified exterior surface is formed thereon and where a protective refractory barrier layer (reaction layer) is formed whose penetration into the droplets is limited by the presence of the solidified surface so as to avoid selective reduction of key reactive alloyants needed to achieve desired powder end use properties. The barrier layer protects the reactive powder particles from environmental constituents such as air and water in the liquid or vapor form during subsequent fabrication of the powder to end-use shapes and during use in the intended service environment.

Anderson, Iver E. (Ames, IA); Lograsso, Barbara K. (Ames, IA); Terpstra, Robert L. (Ames, IA)

1998-09-22

432

Apparatus for making environmentally stable reactive alloy powders  

DOEpatents

Apparatus and method for making powder from a metallic melt by atomizing the melt to form droplets and reacting the droplets downstream of the atomizing location with a reactive gas. The droplets are reacted with the gas at a temperature where a solidified exterior surface is formed thereon and where a protective refractory barrier layer (reaction layer) is formed whose penetration into the droplets is limited by the presence of the solidified surface so as to avoid selective reduction of key reactive alloyants needed to achieve desired powder end use properties. The barrier layer protects the reactive powder particles from environmental constituents such as air and water in the liquid or vapor form during subsequent fabrication of the powder to end-use shapes and during use in the intended service environment.

Anderson, Iver E. (Ames, IA); Lograsso, Barbara K. (Ames, IA); Terpstra, Robert L. (Ames, IA)

1996-12-31

433

High precision pulsed selective laser sintering of metallic powders  

NASA Astrophysics Data System (ADS)

The generative process of selective laser sintering of powders such as Titanium, Platinum alloys and steel can in comparison to cw radiation significantly be improved by using pulsed radiation. With an appropriate energy deposition in the metallic powder layer, the material properties of the selective laser sintered parts can locally be tailored to the requirements of the finished work piece. By adapting the laser parameters of a Q-switched Nd:YAG laser, notably pulse duration and local intensity, the degree of porosity, density and even the crystalline microstructure can be controlled. Pulsed interaction allows minimizing the average power needed for consolidation of the metallic powder, and leads to less residual thermal stresses. With laser post processing, the surface can achieve bulk-like density. Furthermore, we present the possibility of forming metallic glass components by sintering amorphous metallic powders.

Fischer, Pascal; Romano, Valerio; Blatter, Andreas; Weber, Heinz P.

2005-06-01

434

21 CFR 73.40 - Dehydrated beets (beet powder).  

Code of Federal Regulations, 2013 CFR

...Identity. (1) The color additive dehydrated beets is a dark red powder prepared by dehydrating sound, mature, good quality...additive shall conform to the following specifications: Volatile matter, not more than 4 percent. Acid insoluble ash, not...

2013-04-01

435

21 CFR 520.1628 - Oxfendazole powder and pellets.  

Code of Federal Regulations, 2010 CFR

...small strongyles. (3) Limitations —(i) Powder for suspension. For gravity administration via stomach tube or for positive administration via stomach tube and dose syringe. Discard unused portions of suspension after 24...

2010-04-01

436

21 CFR 520.1628 - Oxfendazole powder and pellets.  

Code of Federal Regulations, 2012 CFR

...small strongyles. (3) Limitations —(i) Powder for suspension. For gravity administration via stomach tube or for positive administration via stomach tube and dose syringe. Discard unused portions of suspension after 24...

2012-04-01

437

21 CFR 520.1628 - Oxfendazole powder and pellets.  

Code of Federal Regulations, 2011 CFR

...small strongyles. (3) Limitations —(i) Powder for suspension. For gravity administration via stomach tube or for positive administration via stomach tube and dose syringe. Discard unused portions of suspension after 24...

2011-04-01

438

21 CFR 520.1628 - Oxfendazole powder and pellets.  

...small strongyles. (3) Limitations —(i) Powder for suspension. For gravity administration via stomach tube or for positive administration via stomach tube and dose syringe. Discard unused portions of suspension after 24...

2014-04-01

439

21 CFR 520.1628 - Oxfendazole powder and pellets.  

Code of Federal Regulations, 2013 CFR

...small strongyles. (3) Limitations —(i) Powder for suspension. For gravity administration via stomach tube or for positive administration via stomach tube and dose syringe. Discard unused portions of suspension after 24...

2013-04-01

440

21 CFR 520.110 - Apramycin sulfate soluble powder.  

Code of Federal Regulations, 2013 CFR

...ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES...Specifications. A water soluble powder used...pounds of body weight. Water consumption should be monitored...adjusted according to water consumption which varies...

2013-04-01

441

21 CFR 520.110 - Apramycin sulfate soluble powder.  

Code of Federal Regulations, 2011 CFR

...ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES...Specifications. A water soluble powder used...pounds of body weight. Water consumption should be monitored...adjusted according to water consumption which varies...

2011-04-01

442

21 CFR 520.110 - Apramycin sulfate soluble powder.  

Code of Federal Regulations, 2010 CFR

...ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES...Specifications. A water soluble powder used...pounds of body weight. Water consumption should be monitored...adjusted according to water consumption which varies...

2010-04-01

443

Metastable nanosized aluminum powder as a reactant in energetic formulations  

SciTech Connect

Aluminum powder is an important ingredient in many propellant, explosives and pyrotechnic applications. The production of nanosized aluminum powder by the electroexplosion of metal wire has been practices in the former USSR since the mid 1970`s. Differential scanning calorimetry, differential thermal analysis and x-ray phase analysis was performed on aluminum powder both before and after air passivation, as well as aluminum that was protected under kerosene, pentane, toluene and hexane. Earlier Soviet reports of unexplained thermal releases and metastable behavior have been investigated. Anomalous behavior previously reported included phase transformations at temperatures far below melting with the release of heat and chemoluminescence and self sintering of particles with a heat release large enough to melt the powders.

Katz, J. [Los Alamos National Lab., NM (United States); Tepper, F. [Argonide Corp., Sanford, FL (United States); Ivanov, G.V. [Inst. of Petroleum Chemistry, Tomsk (Russian Federation); Lerner, M.I.; Davidovich, V. [Republic Engineering Center, Tomsk (Russian Federation)

1998-12-01

444

Process for synthesizing compounds from elemental powders and product  

DOEpatents

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

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

1993-12-14

445

RESEARCH ARTICLES Dry Powder Inhaler Device Influence on Carrier Particle  

E-print Network

RESEARCH ARTICLES Dry Powder Inhaler Device Influence on Carrier Particle Performance MARTIN J experience different aerodynamic and mechanical forces depending on the in- haler. However, the influence remains largely unexplored. Carrier particle trajectories through two commercial DPIs were modeled

Raman, Venkat

446

21 CFR 73.40 - Dehydrated beets (beet powder).  

Code of Federal Regulations, 2012 CFR

...Identity. (1) The color additive dehydrated beets is a dark red powder prepared by dehydrating sound, mature, good quality...additive shall conform to the following specifications: Volatile matter, not more than 4 percent. Acid insoluble ash, not...

2012-04-01

447

21 CFR 73.40 - Dehydrated beets (beet powder).  

Code of Federal Regulations, 2010 CFR

...Identity. (1) The color additive dehydrated beets is a dark red powder prepared by dehydrating sound, mature, good quality...additive shall conform to the following specifications: Volatile matter, not more than 4 percent. Acid insoluble ash, not...

2010-04-01

448

21 CFR 73.40 - Dehydrated beets (beet powder).  

Code of Federal Regulations, 2011 CFR

...Identity. (1) The color additive dehydrated beets is a dark red powder prepared by dehydrating sound, mature, good quality...additive shall conform to the following specifications: Volatile matter, not more than 4 percent. Acid insoluble ash, not...

2011-04-01

449

Occupational exposure to elemental constituents in fingerprint powders  

SciTech Connect

Fingerprint detection is an essential component of any crime detection agency. Little information is available regarding the elemental constituents of powders that are available currently. One recent case of lead poisoning coupled with many complaints from the Vancouver identification Squad members initiated a study regarding the elemental composition of, and the occupational exposure to, these powders. Multi-elemental analysis of the powders investigated showed that all contained varying amounts of aluminum, calcium, zinc, iron, magnesium, manganese, and nickel. One powder, however, contained 41% lead. The time spent at the scene of crime during a normal working shift averaged 95.5 min. Assessment of inhalation exposure during this period by personal air sampling pumps never exceeded the occupational exposure standards for these elements. Secondary exposure from dust-contaminated police vehicles and clothing can be an important contributor to overall exposure.

Van Netten, C.; Souter, F.; Teschke, K.E. (Univ. of British Columbia, Vancouver (Canada))

1990-03-01

450

Barium titanium glycolate: A new barium titanate powder precursor  

SciTech Connect

This paper describes the synthesis and structure of a barium titanium glycolate complex and the calcination into barium titanate preceramic powders that sinter into polycrystalline, tetragonal barium titanate having good dielectric properties.

Day, V.W.; Klemperer, W.G.; Payne, D.A. [Univ. of Nebraska, Lincoln, NE (United States)] [and others] [Univ. of Nebraska, Lincoln, NE (United States); and others

1996-02-01

451

57. POWDER MAGAZINE, DETAIL VIEW OF NORTHEAST FRONT ENTRANCE TO ...  

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

57. POWDER MAGAZINE, DETAIL VIEW OF NORTHEAST FRONT ENTRANCE TO ACESS PASSAGE TO MAGAZINES FROM INTERIOR OF MAGAZINE SHOWING VENTILATION WINDOWS (BARRED) FLANKING ENTRANCE DOOR (OPEN). NOTE ACCESS PASSAGE TO ADJOING MAGAZINE. - Fort Monroe, Fortress, Hampton, Hampton, VA

452

49. POWDER MAGAZINE, DETAIL OF ENTRANCE FROM ACCESS PASSAGE SHOWING ...  

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

49. POWDER MAGAZINE, DETAIL OF ENTRANCE FROM ACCESS PASSAGE SHOWING BARRED VENTILATION WINDOWS FLANKING DOORWAY, AND GRANITE STONE SURROUND FROM BOTH, LOOKING NORTHEAST TO SOUTHWEST TOWARDS REAR OF MAGAZINE - Fort Monroe, Fortress, Hampton, Hampton, VA

453

Analysis of powder compaction process through equal channel angular extrusion  

E-print Network

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

Kaushik, Anshul

2009-05-15

454

21 CFR 872.6660 - Porcelain powder for clinical use.  

Code of Federal Regulations, 2011 CFR

...veneers. The device is used in prosthetic dentistry by heating the powder mixture to a high temperature in an oven to produce a hard prosthesis with a glass-like finish. (b) Classification. Class...

2011-04-01

455

21 CFR 872.6660 - Porcelain powder for clinical use.  

Code of Federal Regulations, 2012 CFR

...veneers. The device is used in prosthetic dentistry by heating the powder mixture to a high temperature in an oven to produce a hard prosthesis with a glass-like finish. (b) Classification. Class...

2012-04-01

456

21 CFR 872.6660 - Porcelain powder for clinical use.  

Code of Federal Regulations, 2013 CFR

...veneers. The device is used in prosthetic dentistry by heating the powder mixture to a high temperature in an oven to produce a hard prosthesis with a glass-like finish. (b) Classification. Class...

2013-04-01

457

21 CFR 872.6660 - Porcelain powder for clinical use.  

Code of Federal Regulations, 2010 CFR

...veneers. The device is used in prosthetic dentistry by heating the powder mixture to a high temperature in an oven to produce a hard prosthesis with a glass-like finish. (b) Classification. Class...

2010-04-01

458

21 CFR 872.6660 - Porcelain powder for clinical use.  

...veneers. The device is used in prosthetic dentistry by heating the powder mixture to a high temperature in an oven to produce a hard prosthesis with a glass-like finish. (b) Classification. Class...

2014-04-01

459

The spectroscopic detection of drugs of abuse in fingerprints after development with powders and recovery with adhesive lifters  

NASA Astrophysics Data System (ADS)

The application of powders to fingerprints has long been established as an effective and reliable method for developing latent fingerprints. Fingerprints developed in situ at a crime scene routinely undergo lifting with specialist tapes and are then stored in evidence bags to allow secure transit and also to preserve the chain of evidence. In a previous study we have shown that exogenous material within a fingerprint can be detected using Raman spectroscopy following development with powders and lifting with adhesive tapes. Other reports have detailed the use of Raman spectroscopy to the detection of drugs of abuse in latent fingerprints including cyanoacrylate-fumed fingerprints. This study involves the application of Raman spectroscopy for the analysis of drugs of abuse in latent fingerprints for fingerprints that had been treated with powders and also subsequently lifted with adhesive tapes. Samples of seized ecstasy, cocaine, ketamine and amphetamine were supplied by East Sussex Police and by the TICTAC unit at St. Georges Hospital Tooting. Contaminated fingerprints were deposited on clean glass slides. The application of aluminium or iron based powders to contaminated fingerprints did not interfere with the Raman spectra obtained for the contaminants. Contaminated fingerprints developed with powders and then lifted with lifting tapes were also examined. The combination of these two techniques did not interfere with the successful analysis. The lifting process was repeated using hinge lifters. As the hinge lifters exhibited strong Raman bands the spectroscopic analysis was more complex and an increase in the number of exposures to the detector allowed for improved clarification. Spectral subtraction was performed to remove peaks due to the hinge lifters using OMNIC software. Raman spectra of developed and lifted fingerprints recorded through evidence bags were obtained and it was found that the detection process was not compromised. Although the application of powders did not interfere with the detection process the time taken to locate the contaminant was increased due to the physical presence of more material within the fingerprint.

West, Matthew J.; Went, Michael J.

2009-01-01

460

Spectroscopic characterization of Fe2+-doped II-VI ternary and quaternary mid-IR laser active powders  

NASA Astrophysics Data System (ADS)

We report on spectroscopic characterization of laser active powders based on iron doped II-VI ternary and quaternary semiconductors for mid-IR laser applications. Iron doped Cd1-x MnxTe, Cd1-x MnxS, Cd1-xMnxSe, Cd0.5Mn0.5S0.5Se0.5 , Cd1-xZnxTe compounds with x=0.5-0.25, were prepared by using thermo diffusion technique. The starting binary powders were mixed in the appropriate molar ratios, sealed in evacuated (10-3 Torr) quartz ampoules, and annealed at 800-1000oC for several days. Samples composition, integrity, and grain size were characterized by micro-Raman and Xray diffraction and revealed a variation of the crystal field parameters depending on powder composition. Fe2+ photoluminescence was characterized by spectral band position (normalized with respect to the detection platform spectral sensitivity) and lifetime at different temperatures, enabling calculation of the absorption and emission crosssections. Practical utility of the developed powders was demonstrated by a room temperature random lasing of iron doped Cd0.5Zn0.5Te powders over 5620-6020 nm spectral range pumped by a 2.94 ?m radiation of a Q-switched Er:YAG laser. In summary, the following has been accomplished: (1) It was demonstrated that laser active Fe2+ doped ternary and quaternary II-VI materials can be produced by simple annealing of the commercially available binary powders omitting expensive and complicated crystal growth processes; (2) It is possible to effectively shift PL of Fe2+ in II-VI host materials towards shorter or longer wavelength by varying composition, type and amount of the second cation in ternary II-VI materials; (3) Major spectroscopic characteristics of Fe2+ doped II-VI ternary and quaternary compounds were obtained and their practical utility for mid-IR lasing demonstrated.

Martinez, A.; Martyshkin, D. V.; Fedorov, V. V.; Mirov, S. B.

2014-02-01

461

Neutron detectors comprising ultra-thin layers of boron powder  

DOEpatents

High-efficiency neutron detector substrate assemblies comprising a first conductive substrate, wherein a first side of the substrate is in direct contact with a first layer of a powder material having a thickness of from about 50 nm to about 250 nm and 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, Zhehul; Morris, Christopher

2013-07-23

462

Cesium powder and pellets inner container decontamination method determination  

SciTech Connect

The cesium powder and pellets inner container is to be performance tested per the criteria specified in Section 4.0 of HNF-2399, ``Design, Fabrication, and Assembly Criteria for Cesium Powder and Pellet Inner Container.`` The test criteria specifies that the inner container be water tight during decontamination of the exterior surface. Three prototypes will be immersed into a pool of water to simulate a water decontamination process.

Ferrell, P.C.

1998-07-09

463

DETONATION PROPERTIES OF EXPLOSIVES CONTAINING NANOMETRIC ALUMINUM POWDER  

Microsoft Academic Search

Nanometric aluminum powder is known to react more rapidly than conventional, micron-size aluminum grades in propellant and explosive compositions. Defence Research and Development Canada - Valcartier (DRDC-V) and the Defence Science and Technology Organisation (DSTO) are collaborating to assess the potential of nanometric aluminum powders in explosive compositions. Various plastic-bonded explosives (PBXs) and TNT-based formulations have been developed to compare

Patrick Brousseau; Helen E. Dorsett; Matthew D. Cliff; C. John Anderson

464

Nanodispersed metal powders in high-energy condensed systems  

Microsoft Academic Search

The results of earlier published Russian and foreign works concerning the use of nanodispersed metal powders in high-energy\\u000a condensed systems (HECSs) are analyzed and generalized. Modern technological achievements allow one to produce powders of\\u000a aluminum, boron, and other metals, as well as their alloys and oxides, and make them commercially available. This has resulted\\u000a in a boom in studies on

S. G. Fedorov; Sh. L. Guseinov; P. A. Storozhenko

2010-01-01

465

Physicochemical Characterization of Whole Egg Powder Microencapsulated by Spray Drying  

Microsoft Academic Search

Physical characterization and oxidative stability of egg powder microencapsulated by spray drying were studied in this work. The wall material (gelatin, lactose, pullulan, and their mixtures) and liquid egg mixtures were prepared by homogenization at 22,000 rpm for 60 s. The spray drying was carried out at pilot-scale spray dryer (Niro Mobile Minor, Søborg, Denmark). The spray-dried egg powders were analyzed for

Mehmet Koç; Banu Koç; Melike Sakin Yilmazer; Figen Kaymak Ertekin; Gonca Susyal; Neriman Ba?datl?o?lu

2011-01-01

466

Caking of Water-Soluble Amorphous and Crystalline Food Powders  

Microsoft Academic Search

\\u000a Water-soluble chemicals, detergents, pharmaceuticals, and food powders often become sticky during handling at high temperature\\u000a or humidity. Increasing the storage time at elevated temperature and humidity frequently leads to a time consolidation (called\\u000a caking) of such powders. To clarify the mechanism of stickiness and caking, it is required that one understands the adhesion\\u000a forces between single particles. The adhesion forces

Stefan Palzer; Karl Sommer

467

Powder material parameters establishment through warm forming route  

Microsoft Academic Search

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

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

2011-01-01

468

Air-plasma spraying colloidal solutions of nanosized ceramic powders  

Microsoft Academic Search

Coatings prepared from nanosized powders were obtained by spraying ethanol-based colloidal solutions into a plasma plume. The powders investigated included 40 nm ?-Al2O3, 75 nm 8 wt% Y2O3-ZrO2, and 750 nm 25 wt% CeO2-ZrO2. Spray distances from approximately 50 to 63 mm were required to achieve significant coating deposition. As observed in the TEM, the typical lamella morphology of air

Zun Chen; Rodney W. Trice; M. Besser; Xiaoyun Yang; D. Sordelet

2004-01-01

469

Thermodynamics of toxic gas molecules on metal oxide nano powders  

Microsoft Academic Search

Studies on physical\\/chemical reactions of gas molecules on nano sized metal oxide powder surface is interesting because the results from the research can directly be applied to the investigation of the surface mediated catalytic reactions aimed at reducing atmospheric pollutants. Thermodynamic properties of nitrous oxides (NOx) on varies nano sized metal oxides such as MgO and ZnO powders were studied

Jae-Yong Kim; Chae-Ok Kim

2005-01-01

470

Powder-metallurgy superalloy strengthened by a secondary gamma phase.  

NASA Technical Reports Server (NTRS)

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

Kotval, P. S.

1971-01-01

471

Protective matching polymer powder coating of piezoelectric element  

NASA Astrophysics Data System (ADS)

Objects of research are coatings and technology of their applying to the piezoelectric elements for ultrasound. Acoustic impedance and thicknesses of matching layers for medical ultrasound transducers have been defined. In this paper performance characteristics