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1

Second harmonic generation of ? 5-monocyclopentadienyl ruthenium p-benzonitrile derivatives by Kurtz powder technique. Crystal and molecular structure determinations of [Ru(? 5-C 5H 5)((+)DIOP)( p-NCC 6H 4NO 2)][X], X=PF 6 ?, CF 3SO 3 ? and [Ru(? 5-C 5H 5)((+)DIOP)(NCCH 3)][PF 6  

Microsoft Academic Search

A new series of salts [RuCp(PP)(p-N?C(CH?CH)nC6H4R)][X] (PP=((+)-DIOP, DPPE; n=0, 1; R=CH3, Br, OCH3, NH2, N(CH3)2, C6H5 and NO2; X=PF6?, CF3SO3?) were synthesised and the second harmonic generation (SHG) efficiencies were measured by Kurtz powder technique in order to better understand the relationship between structural features and solid state packing with SHG properties. A structural study of [RuCp((+)-DIOP)(p-N?CC6H4NO2)][X], X=PF6?, CF3SO3? by

M. Helena Garcia; João C. Rodrigues; A. Romão Dias; M. Fátima M. Piedade; M. Teresa Duarte; M. Paula Robalo; Nelson Lopes

2001-01-01

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

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.

2013-12-01

4

Role of the Drosophila Non-Visual ss-Arrestin Kurtz in Hedgehog Signalling  

PubMed Central

The non-visual ß-arrestins are cytosolic proteins highly conserved across species that participate in a variety of signalling events, including plasma membrane receptor degradation, recycling, and signalling, and that can also act as scaffolding for kinases such as MAPK and Akt/PI3K. In Drosophila melanogaster, there is only a single non-visual ß-arrestin, encoded by kurtz, whose function is essential for neuronal activity. We have addressed the participation of Kurtz in signalling during the development of the imaginal discs, epithelial tissues requiring the activity of the Hedgehog, Wingless, EGFR, Notch, Insulin, and TGF? pathways. Surprisingly, we found that the complete elimination of kurtz by genetic techniques has no major consequences in imaginal cells. In contrast, the over-expression of Kurtz in the wing disc causes a phenotype identical to the loss of Hedgehog signalling and prevents the expression of Hedgehog targets in the corresponding wing discs. The mechanism by which Kurtz antagonises Hedgehog signalling is to promote Smoothened internalization and degradation in a clathrin- and proteosomal-dependent manner. Intriguingly, the effects of Kurtz on Smoothened are independent of Gprk2 activity and of the activation state of the receptor. Our results suggest fundamental differences in the molecular mechanisms regulating receptor turnover and signalling in vertebrates and invertebrates, and they could provide important insights into divergent evolution of Hedgehog signalling in these organisms.

Molnar, Cristina; Ruiz-Gomez, Ana; Martin, Mercedes; Rojo-Berciano, Susana; Mayor, Federico; de Celis, Jose F.

2011-01-01

5

The development of an alternative thermoplastic powder prepregging technique  

NASA Technical Reports Server (NTRS)

Discussed is a novel powder prepregging technique that is based on the deposition of the powder onto fibers that have been moistened using an ultrasonic humidifier. The moisture acts as an initial binding agent for the powder until the powder can be melted onto the fiber in a subsequent heating step. LaRC-TPI powder, produced by Mitsui Toastsu, and Hercules AS-4 fiber served as the process development material system. The influence of powder particle size on this process, and the quality of the resulting composite are discussed.

Ogden, A. L.; Hyer, M. W.; Muellerleile, J. T.; Wilkes, G. L.; Loos, A. C.

1990-01-01

6

Optimal design of powder compaction processes via genetic algorithm technique  

Microsoft Academic Search

In this paper, an optimal design is performed for powder die-pressing process based on the genetic algorithm approach. It includes the shape optimization of powder component, the optimal design of punch movements, and the friction optimization of powder–tool interface. The genetic algorithm is employed to perform an optimal design based on a fixed-length vector of design variables. The technique is

A. R. Khoei; Sh. Keshavarz; S. O. R. Biabanaki

2010-01-01

7

Spectrochemical analysis of boron carbide by powder techniques. Final report  

Microsoft Academic Search

A method for the determination of impurities in boron carbide was developed using powder techniques. The elements aluminum, calcium, iron, magnesium, manganese, nickel, silicon, titanium, and vanadium were determined over concentration ranges between 10 and 24,000 parts per million. The boron carbide powder was mixed with buffers including an internal standard. These sample mixtures were excited in a direct current

B. H. Strauss; F. G. Howell

1977-01-01

8

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

9

Pyrolytic preparations of ceramic powders by a spray calcination technique  

Microsoft Academic Search

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

D. Vollath

1990-01-01

10

?-arrestin Kurtz inhibits MAPK and Toll signalling in Drosophila development  

PubMed Central

?-Arrestins have been implicated in the regulation of multiple signalling pathways. However, their role in organism development is not well understood. In this study, we report a new in vivo function of the Drosophila ?-arrestin Kurtz (Krz) in the regulation of two distinct developmental signalling modules: MAPK ERK and NF-?B, which transmit signals from the activated receptor tyrosine kinases (RTKs) and the Toll receptor, respectively. Analysis of the expression of effectors and target genes of Toll and the RTK Torso in krz maternal mutants reveals that Krz limits the activity of both pathways in the early embryo. Protein interaction studies suggest a previously uncharacterized mechanism for ERK inhibition: Krz can directly bind and sequester an inactive form of ERK, thus preventing its activation by the upstream kinase, MEK. A simultaneous dysregulation of different signalling systems in krz mutants results in an abnormal patterning of the embryo and severe developmental defects. Our findings uncover a new in vivo function of ?-arrestins and present a new mechanism of ERK inhibition by the Drosophila ?-arrestin Krz.

Tipping, Marla; Kim, Yoosik; Kyriakakis, Phillip; Tong, Mei; Shvartsman, Stanislav Y; Veraksa, Alexey

2010-01-01

11

Nano powders, components and coatings by plasma technique  

NASA Technical Reports Server (NTRS)

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. (Inventor); Antony, Leo V. M. (Inventor); O'Dell, Scott (Inventor); Power, Chris (Inventor); Tabor, Terry (Inventor)

2009-01-01

12

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

13

The development of an alternative thermoplastic powder prepregging technique  

NASA Technical Reports Server (NTRS)

An alternative powder prepregging technique is discussed that is based on the deposition of powder onto carbon fibers that have been moistened using an ultrasonic humidifier. The dry fiber tow is initially spread to allow a greater amount of the fiber surface to be exposed to the powder, thus ensuring a significant amount of intimate contact between the fiber and the matrix. Moisture in the form of ultrafine water droplets is then deposited onto the spread fiber tow. The moisture promotes adhesion to the fiber until the powder can be tacked to the fibers by melting. Powdered resin is then sieved onto the fibers and then tacked onto the fibers by quick heating in a convective oven. This study focuses on the production of prepregs and laminates made with LaRC-TPI (thermoplastic polyimide) using this process. Although the process appears to be successful, early evaluation was hampered by poor interfacial adhesion. The adhesion problem, however, seems to be the result of a material system incompatibility, rather than being influenced by the process.

Ogden, A. L.; Hyer, M. W.; Wilkes, G. L.; Loos, A. C.

1992-01-01

14

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

Microsoft Academic Search

The objectives of this work were (i) to validate electrical zone sensing and laser diffraction for the analysis of primary particle size in the case of inhalation dry powders and (ii) to study the influence of the aggregation state of the powder on the sizing techniques. Free-flowing dry powders were prepared by spray-drying with a combination of albumin, lactose, and

Cynthia Bosquillon; Catherine Lombry; Veronique Preat; Rita Vanbever

2001-01-01

15

Nanostructured hydroxyapatite powders produced by a flame-based technique  

Microsoft Academic Search

In this work we reported the production of hydroxyapatite (HA) powder, one of the most studied calcium phosphates in the bioceramics field, using a cost-effective apparatus, composed by three major components: the atomization device, the pilot and main flames and finally the powder collector system. Calcium acetate and ammonium phosphate, diluted in ethanol and water, were used as salts in

R. M. Trommer; L. A. Santos; C. P. Bergmann

2009-01-01

16

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

SciTech Connect

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

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

2011-12-31

17

NIRS and MIRS technique for the determination of protein and fat content in milk powder  

NASA Astrophysics Data System (ADS)

It is very important to detect the protein and fat content in milk powder fast and non-destructively. Near-infrared (NIR) and mid-infrared(MIR) spectroscopy techniques have been compared and evaluated for the determination of the protein and fat content in milk powder with the use of Least-squares support vector machines (LS-SVM). LS-SVM models have been developed by using both NIR and MIR spectra. Both methods have shown good correlations between infrared transmission values and two nutrition contents. MIRS provided better prediction performance over NIRS. It is concluded that infrared spectroscopy technique can quantify of the protein and fat content in milk powder fast and nondestructively. The process is simple and easy to operate than chemistry methods. The results can be beneficial for designing a simple and non-destructive instrument with MIRS or NIRS spectral sensor for the determination of the protein fat content in milk powder.

Wu, Di; Feng, Shuijuan; He, Chao; He, Yong

2008-03-01

18

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

19

Influence of formulation and process parameters on pellet production by powder layering technique.  

PubMed

The goal of the present study was to evaluate the influence of the formulation and operating conditions on pellet preparation by pan technique. To this end, a new pelletization process, typified by the application of powdered drug on sugar-based cores using the GS coating system was studied. Inert cores were intermittently treated with micronized drug powder and adhesive solution. This treatment led to the formation of multiple layers of drug particles around an inert core resulting in the production of pellets that can further be coated by different polymers to obtain modified release formulations. Different procedures have been used to evaluate a series of important parameters such as initial core weight; speed of powder application; speed, type, and position of the atomizers; atomization degree; temperature; and air cap. Good yield of drug layering was obtained by adjusting the quantity of both the drug powder to apply and the binder solution. Pellets obtained following the optimal operating conditions (defined in a pre-formulation study) were film coated with the acrylic polymer Eudragit L30D in order to produce a model formulation consisting of enteric polymer-coated pellets containing ibuprofen. During its preparation, the formulation showed no degradation of the drug; moreover, a low percentage of residual humidity was obtained, indicating that this system is very efficient for the production of highly stable formulations. This study showed the good performance of the GS automated pan-coating system in obtaining enteric coated pellets prepared by powder layering technique using aqueous solutions. PMID:14727842

Nastruzzi, C; Cortesi, R; Esposito, E; Genovesi, A; Spadoni, A; Vecchio, C; Menegatti, E

2000-01-01

20

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

Microsoft Academic Search

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

L. Ma. Flores-Vélez; J. Chávez; L. Hernández; O. Domínguez

2001-01-01

21

Diagnostic techniques of talc powder in flour based on the THz spectroscopy  

NASA Astrophysics Data System (ADS)

The terahertz time-domain spectroscopy technique is used to test flour/talc powder mixture samples. It is found that the two samples have obvious absorption peaks and different refractive index. The results provided in this paper will help us to study the THz application to the field of food safety.

Xiao-li, Zhao; Jiu-sheng, Li

2011-02-01

22

An improved technique for accurate heat capacity measurements on powdered samples using a commercial relaxation calorimeter  

Microsoft Academic Search

We have modified our earlier technique for accurate PPMS heat capacity measurements on powdered samples by means of applying Wakefield grease or small copper strips in the sample preparation instead of using Apiezon N high-vacuum grease. For the Wakefield grease measurements, we put a small amount of Wakefield thermal compound in a copper cup instead of potting with Apiezon N,

Quan Shi; Juliana Boerio-Goates; Brian F. Woodfield

2011-01-01

23

Evaluation of cryogenic impact grinding technique for powdering whole fish for metal determinations.  

PubMed

A cryogenic grinding technique, which involves brittle fracture of samples by impact pressure, was evaluated for the final reduction of whole-fish samples for subsequent metal determinations. The technique incorporated a number of desirable features: protection of heat-labile components; incorporation of lyophilization to facilitate handling and storage; requirement of few procedural steps; short grinding time per sample; and easy, rapid cleanup of equipment. Particle size in the ground powder was less than 100 microns. Problems associated with the technique were contamination of fish samples with Cr, Fe, Mo, and Ni; limited size of the grinding container; and powder clumping caused by the presence of lipids. Approaches to alleviate these problems are discussed. PMID:6746482

May, T W; Kaiser, M L

1984-01-01

24

The mechanical properties of Fe-Co heterogeneous alloys fabricated by powder metallurgy techniques  

Microsoft Academic Search

Fe-Co heterogeneous alloys fabricated by powder metallurgy techniques were hot rolled, cold rolled and then heat treated. These processes produced a type of fibre-reinforced composite which consisted of fibrous Fe and Fe-Co phases. The tensile strength of the alloys depended on the composition and degree of order of the Fe-Co phase. The rule of mixtures was applicable, provided that the

Morihiko Nakamura; Kazuo Tsuya

1977-01-01

25

Comparative study of natural and man-made polymers using whole powder pattern fitting technique  

Microsoft Academic Search

Natural polymers like chitosan, hemp and man-made polymers like poly(ethylene oxide)(PEO) and hydroxypropyl methylcellulose\\u000a (HPMC) were investigated using wide angle X-ray scattering (WAXS) method. The merits and demerits of natural and man-made\\u000a polymers were quantified in terms of microcrystalline parameters, determined by whole powder pattern fitting technique, which\\u000a is an extension of single order method developed by us.

S. Divakara; G. N. Siddaraju; R. Somashekar

2010-01-01

26

Strength and electrical conductivity of deformation-processed Cu15 Vol Pct Fe alloys produced by powder metallurgy techniques  

Microsoft Academic Search

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

G. A. Jerman; I. E. Anderson; J. D. Verhoeven

1993-01-01

27

Investigation of the structure of ettringite by time-of-flight neutron powder diffraction techniques  

SciTech Connect

The crystalline structure of ettringite, Ca{sub 6}[Al(OH){sub 6}]{sub 2}(SO{sub 4}){sub 3}.{approx}26H{sub 2}O, was investigated using high-resolution time-of-flight neutron powder diffraction techniques. The powder diffraction data were subjected to Rietveld crystal structure refinement. The resultant ettringite crystal structure confirmed the positions of Ca, Al, and S atoms while permitting a more precise determination of the locations of O and H atomic positions than in previous X-ray and neutron diffraction studies. A discussion of the ettringite hydrogen bonding network is presented, illustrating the role of hydrogen bonding in the stabilization of the ettringite structure.

Hartman, M.R. [University of Michigan, Ann Arbor, MI 48109 (United States)]. E-mail: michael.hartman@nist.gov; Berliner, R. [University of Michigan, Ann Arbor, MI 48109 (United States)

2006-02-15

28

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

PubMed

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

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

2014-07-01

29

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

NASA Astrophysics Data System (ADS)

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

Jetté, François-Xavier; Goroshin, Sam; Higgins, Andrew; Frost, David; Lee, Julian

2011-06-01

30

Phase quantification of mullite-zirconia and zircon commercial powders using PAC and XRD techniques  

NASA Astrophysics Data System (ADS)

The short range technique of the Perturbed Angular Correlation (PAC) and x-ray diffraction (Rietveld) methods have been employed to determine the phase content in commercial mullite-zirconia and zircon raw materials that are ordinarily used to produce ceramic materials. The PAC technique, which probes zirconium-containing compounds at nanoscopic level, showed that zircon contains crystalline ZrSiO4 and an important amount of a structurally distorted zircon, which is also observed accompanying monoclinic zirconia in mullite-zirconia. This particular zircon phase was not detected by the long range x-ray diffraction-Rietveld technique. After an annealing treatment, important changes in crystalline contents of the powders allow confirming, by the x-ray diffraction-Rietveld method, the preexistence of this particular zircon phase. This fact must be taken into account when preparing multicomposites based on the present raw materials.

Rendtorff, Nicolás M.; Conconi, Maria S.; Aglietti, Esteban F.; Chain, Cecilia Y.; Pasquevich, Alberto F.; Rivas, Patricia C.; Martínez, Jorge A.; Caracoche, María C.

2010-06-01

31

Preparation of various calcium-phosphate powders by ultrasonic spray freeze-drying technique  

Microsoft Academic Search

Various calcium–phosphate powders with Ca\\/P ratios ranging from 1.00 to 1.67 were prepared by an ultrasonic spray freeze-drying (USFD) technique: (i) 100 cm3 of aqueous solution containing 0.500 mol·dm?3 of calcium acetate (Ca(CH3COO)2), 0.300–0.500 mol·dm?3 of trimethyl phosphate (PO(OCH3)3) and 1.77 mol·dm?3 of acetic acid (CH3COOH) were refluxed at 80°C for 100 h; (ii) the droplets with diameters as small

Kiyoshi Itatani; Kengo Iwafune; F. Scott Howell; Mamoru Aizawa

2000-01-01

32

Strength and electrical conductivity of deformation-processed Cu15 Vol Pct Fe alloys produced by powder metallurgy techniques  

Microsoft Academic Search

Powder metallurgical techniques have been employed to prepare the precursor billets in the preparation of Cu-15 vol pct Fe\\u000a alloys by deformation processing. It has been demonstrated that by (1) using high-purity gas-atomized Cu powders blended with\\u000a commercial high-purity Fe powders and (2) controlling the time\\/temperature processing conditions within specific limits, it\\u000a is possible to produce Cu-Fe deformation-processed alloys with

G. A. Jerman; I. E. Anderson; J. D. Verhoeven

1993-01-01

33

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

NASA Astrophysics Data System (ADS)

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

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

2012-03-01

34

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

35

Concurrent use of metered dose inhalers without spacer and dry powder inhalers by asthmatic children adversely affect proper inhalation technique  

PubMed Central

Asthma is a common chronic disease of children. A good control of symptoms will improve quality of patient life. Inhalation technique is an important aspect in the management of asthma. The better the inhalation technique the better the lung deposition of asthma therapy especially inhaled corticosteroids. This will lead to better control of symptoms and improve adherence to treatment. In the following study the inhalation technique of asthma devices were compared using inhalation technique score system. The asthma devices studied were metered dose inhalers (pressurized MDI) without spacers and dry powder inhalers (DPI). The hypothesis studied was that the inhalation technique score of dry powder inhalers will be adversely affected with concurrent use of metered dose inhalers without spacers.

Alotaibi, Saad; Hassan, Walid M; Alhashimi, Hashim

2011-01-01

36

Recovery of SiC powder from sintered DPF using hydrothermal treatment combined with ball-milling technique  

NASA Astrophysics Data System (ADS)

In the present work, hydrothermal treatment combined with ball-milling technique (HTBT) was attempted to recover SiC powder from bulk sintered DPF. Various parameters including the material and size of the milling-ball, the type of the solvent medium, the rotation speed, the ratio of solvent/DPF, the treatment temperature and time were optimized. The pulverization rate, impurity content and the particle size of the recovered SiC powder were investigated to assess the effect of HTBT. Dilute HF solution was selected as the main solvent and SiC milling-ball was the most suitable for pulverization of the sintered DPF. The rotation speed played a significant role for the pulverization rate and more than 90% of bulk sintered DPF was recovered as SiC powder using SiC balls (5 mm in diameter) in the mixed aqueous solutions of HF (0.05 mol/dm3) and H2O2 (0.25 mol/dm3) with rotation speed >= 275 rpm and solvent/DPF = 1.5 at 200°C after 20 h HTBT . Generally the average grain size of the recovered SiC powder was less than 1.5 ?m and decreased with the extended treatment time and the increased rotation speed. The result of purity analysis showed that the recovered SiC powder totally met the demand of the raw SiC powder for DPF production under the optimized conditions.

Liu, Zhengang; Sasai, Ryo; Itoh, Hideaki

2011-04-01

37

Predicting caking behaviors in powdered foods using a low-field nuclear magnetic resonance (NMR) technique  

Microsoft Academic Search

This study is concerned with caking of powder mixes. Our previous study tied the caking process to the nuclear magnetic resonance (NMR) spin–spin (T2) relaxation characteristics exhibited by powder ingredients subjected to temperature scan from –20°C to 110°C (Journal of Food Science 65 (1) (2000) 134). Four temperature–T2 curve patterns were identified, each of which represents a group of powder

Myong-Soo Chung; Roger Ruan; Paul Chen; Jin-Ho Kim; Tae-Hoi Ahn; Chang-Kyu Baik

2003-01-01

38

Development of powder metallurgy technique for synthesis of U 3Si 2 dispersoid  

NASA Astrophysics Data System (ADS)

The Indian research reactor APSARA, which uses HEU based UAl 3 fuel dispersed in aluminium matrix, is to undergo core conversion to LEU based U 3Si 2 dispersoid in aluminium matrix fuel. Work has been initiated at BARC, to prepare uranium silicide (U 3Si 2) compound using powder processing route in place of vacuum induction melting or arc melting route. This paper describes the preparation flow-sheet of the U 3Si 2 dispersoid by an innovative powder processing route with uranium metal powder and silicon powder as starting materials.

Sinha, V. P.; Mishra, G. P.; Pal, S.; Khan, K. B.; Hegde, P. V.; Prasad, G. J.

2008-12-01

39

Determination of the wettability of powders by the Washburn capillary rise method with bed preparation by a centrifugal packing technique.  

PubMed

The Washburn capillary rise method is a standard technique for determining the wettability of powders expressed as a contact angle. The method requires the preparation of two identical beds of powder. One of these beds is used to follow the capillary rise with a perfectly wetting liquid (contact angle = 0) giving access to a bed structure parameter. The other bed is used with the liquid of interest (contact angle not = 0) and the capillary rise data is analysed using the previously determined structure parameter to obtain the contact angle. In the experiments reported here we have used a centrifugal packing technique to prepare beds of powder. This gives reproducible packings and also allows a certain degree of control of the bed porosity. In addition the air permeability of the beds is also determined prior to the capillary rise experiments. The results show that the value of the contact angle of a powder determined by the Washburn method depends on the porosity of the powder bed, and that the structure parameter can be determined from the air permeability using the Kozeny-Carman expression. PMID:20362998

Galet, Laurence; Patry, Severine; Dodds, John

2010-06-15

40

Preparation of magnesium silicon nitride powder by the carbothermal reduction technique  

Microsoft Academic Search

Magnesium silicon nitride (MgSiN2) powder was prepared by carbothermally reducing a magnesium metasilicate whose chemical composition corresponded to MgO SiO2 or MgSiO3. About 0.2 g of the powder mixture of magnesium metasilicate and carbon (C) with the molar ratio of C to MgO SiO2 equal to 6.0 was heated at 1250°C for 7 h in nitrogen atmosphere. The crystalline phase

Hiroshi Uchida; Kiyoshi Itatani; Mamoru Aizawa; F. S. Howell; Akira Kishioka

1999-01-01

41

Surface tension studies of additives in acrylic resin-based powder coatings using the Wilhelmy balance technique  

Microsoft Academic Search

A modified Wilhelmy balance technique using thin fibers as solid probes has been applied to study the effect of silicone additives in acrylic resin-based powder coatings on the surface tension of non-reactive binder systems. By measuring the temperature dependence of the surface tension in the temperature range between 140 and 180°C, it could be shown that the silicone additives investigated

Karina Grundke; Stefan Michel; Michael Osterhold

2000-01-01

42

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

PubMed

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

Schoubben, Aurélie; Giovagnoli, Stefano; Tiralti, Maria Cristina; Blasi, Paolo; Ricci, Maurizio

2014-07-20

43

Coating of pellets with micronized ethylcellulose particles by a dry powder coating technique.  

PubMed

Pellets were coated with ethylcellulose powder to achieve extended release. The film forming ability of ethylcellulose powder and the effect of formulation factors (plasticizer type and concentration) and curing conditions (curing temperature and time) were investigated. The coating formulation was divided into two components consisting of a powder mixture (polymer plus talc) and a mixture of liquid materials (plasticizer plus binder solution), which were sprayed separately into the coating chamber of a fluidized bed coater (Glatt GPCG-1, Wurster insert). The coated pellets were oven-cured under different conditions (60-80 degrees C, 2-24 h) without and with humidity (100% relative humidity). Propranolol hydrochloride was used as a model drug, and drug release was studied in 0.1 N HCl at 37 degrees C (USP XXV paddle method). Despite the high glass transition temperature of ethylcellulose (133.4 degrees C), micronized ethylcellulose powder can be used for dry powder coating by adjusting the coating temperature, amount and type of plasticizer applied, and curing conditions. 40% plasticizer and a curing step (80 degrees C, 24 h) were required to achieve complete coalescence of the polymer particles and extended drug release of coated pellets. Although ethylcellulose-coated pellets had an uneven surface, extended drug release could be obtained with coating level of 15%. Because of its high glass transition temperature, ethylcellulose-coated pellets showed unchanged drug release profiles upon storage at room temperature for 3 years. PMID:14643971

Pearnchob, Nantharat; Bodmeier, Roland

2003-12-11

44

Precise measurement of the lattice spacing of LaB6 standard powder by the x-ray extended range technique using synchrotron radiation  

Microsoft Academic Search

We used the basis of the x-ray extended range technique to measure the lattice spacing of LaB6 standard powder samples relative to silicon 640b standard powder samples with an accuracy of 5× 10-5 Å . Measurements were not constrained to one energy but were carried out over a 5 keV 20 keV energy range. These measurements used powder diffraction to

C. T. Chantler; C. Q. Tran; D. J. Cookson

2004-01-01

45

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

NASA Astrophysics Data System (ADS)

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

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

2008-03-01

46

In-situ fabrication of nanostructured cobalt oxide powders by spray pyrolysis technique.  

PubMed

Nano-crystalline Co3O4 and CoO powders have been prepared by a spray pyrolysis approach. The effects of the reaction temperature and initial salts on the crystallinity and phase composition have been studied. Based on the TEM and XRD results, the crystal sizes were in the range of 1-10 nm. SEM and TEM observations also reveal that the nano-powders easily create micron-scale spherical agglomerates. The Co3O4 powders obtained by spraying nitrate solution at 500 degrees C show high specific surface area, which according to the BET method is 82.37 m2/g. The time/temperature phase diagram of cobalt oxides developed from XRD and DTA/TGA analyses shows the existence of a CoO phase at low and high temperature ranges when some specific preparation conditions are applied. PMID:15570973

Zhao, Z W; Konstantinov, K; Yuan, L; Liu, H K; Dou, S X

2004-09-01

47

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

SciTech Connect

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

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

2005-05-01

48

Characterization of Fine Powders  

NASA Astrophysics Data System (ADS)

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

Krantz, Matthew; Zhang, Hui; Zhu, Jesse

49

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

Microsoft Academic Search

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

Laura Esposito; Andreana Piancastelli

2009-01-01

50

COMPARISON OF NASAL INSULIN POWDERS PREPARED BY SUPERCRITICAL FLUID AND FREEZE-DRYING TECHNIQUES  

Microsoft Academic Search

In this study, the effect of drug loading on the nasal absorption of insulin was determined. Human insulin was loaded into different drug carriers by two methods: supercritical fluid processing and freeze-drying. The powder formulations were characterized and then evaluated after nasal administration to alloxan induced diabetic rabbits at a dose of 5U\\/kg and 7.5U\\/kg. The blood glucose levels and

HOSSEIN ZIA; POLIREDDY DONDETI; THOMAS E. NEEDHAM

1997-01-01

51

A powder technique for measuring the noncritical phase-matching frequency  

NASA Astrophysics Data System (ADS)

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

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

1990-11-01

52

Development of powder metallurgy technique for synthesis of U 3Si 2 dispersoid  

Microsoft Academic Search

The Indian research reactor APSARA, which uses HEU based UAl3 fuel dispersed in aluminium matrix, is to undergo core conversion to LEU based U3Si2 dispersoid in aluminium matrix fuel. Work has been initiated at BARC, to prepare uranium silicide (U3Si2) compound using powder processing route in place of vacuum induction melting or arc melting route. This paper describes the preparation

V. P. Sinha; G. P. Mishra; S. Pal; K. B. Khan; P. V. Hegde; G. J. Prasad

2008-01-01

53

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

PubMed

The authors have conducted a preliminary investigation with regard to the potential to manufacture porous titanium alloys for biomedical applications using toxic-free elemental powders, i.e., Ti, Nb, Ta, Zr, in combination with the pressurised gas bubble entrapment method and in contrast to standard processing routes that generally utilise prealloyed powder containing potentially toxic elements. Elemental powder compacts were either hot isostatic pressed (HIP-ed) at 1000°C and then foamed at 1150°C or else HIP-ed at 1100°C and foamed at 1350°C. Porous ? + ? alloys containing up to 45 vol% of porosity in the size range 20-200 ?m were successfully produced, thus highlighting the potential of this manufacturing route. It was expected that further optimisation of the processing route would allow full development of the preferred ?-Ti phase (from the point of view of elastic modulus compatibility between implant and bone) with this being the subject of future work by the authors. PMID:20960037

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

2010-12-01

54

Determining the Point of Zero Zeta Potential in Solid Samples: In a new technique, the sample does not have to be in powder form.  

National Technical Information Service (NTIS)

This citation summarizes a one-page announcement of technology available for utilization. Although current techniques for measuring the point of zero zeta potential (pzzp) in semiconductors require that the sample be in powder form, that is not always the...

1984-01-01

55

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

56

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

57

Preparation of Cu and Fly Ash Composite by Powder Metallurgy Technique  

NASA Astrophysics Data System (ADS)

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

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

2011-03-01

58

Characterization of Porosity Distributions of Slurry-Coated and Dry-Powder Plaques Using Conductive Image Technique.  

National Technical Information Service (NTIS)

The porosity distributions of sinter plaques manufactured by dry powder and wet slurry processes were measured using an improved conductive imaging microprobe. This study has indicated that the pore size distributions of dry-powder plaques are more unifor...

A. H. Phan, A. H. Zimmerman, M. V. Quinzio

1995-01-01

59

Gene silencing in a mouse lung metastasis model by an inhalable dry small interfering RNA powder prepared using the supercritical carbon dioxide technique.  

PubMed

In this study, a novel dry small interfering RNA (siRNA) powder for inhalation, containing chitosan and mannitol, was prepared using the supercritical carbon dioxide (CO2) technique. Although the siRNA/chitosan powder was difficult to disperse because of a long needle-like structure, it could be reduced to fragments of 10-20?µm by manual grinding, which allowed for administration into mice. Electrophoresis revealed that the supercritical CO2 technique and manual grinding didn't greatly affect the integrity of the siRNA. Furthermore, the siRNA was more stable in the lungs than in blood, suggesting the utility of pulmonary delivery. Biodistribution experiments using Cy5.5-labeled siRNA demonstrated that pulmonary administration of the powder achieved a prolonged exposure of the siRNA/chitosan complex on the lung epithelial surface at a higher concentration. For the evaluation of the in-vivo gene silencing effect of the siRNA/chitosan powder, mice bearing colon26/Luc cells were used. The powder significantly inhibited the increase in luminescence intensity in the lungs, but the siRNA/chitosan solution and a non-specific dry siRNA/chitosan powder didn't, indicating the effective and specific gene silencing against the tumor cells metastasized in the lungs of mice by the siRNA/chitosan powder. These results strongly indicate that inhalable dry siRNA powders have the possibility of effective pulmonary gene silencing and that the supercritical CO2 technique can be applied to the production. PMID:23811567

Okuda, Tomoyuki; Kito, Daisuke; Oiwa, Ai; Fukushima, Michiko; Hira, Daiki; Okamoto, Hirokazu

2013-01-01

60

Powder diffraction  

Microsoft Academic Search

The powder diffraction method, by using conventional X-ray sources, was devised independently in 1916 by Debye and Scherrer in Germany and in 1917 by Hull in the United States. The technique developed steadily and, half a century later, the `traditional' applications, such as phase identification, the determination of accurate unit-cell dimensions and the analysis of structural imperfections, were well established.

J. Ian Langford; Daniel Louër

1996-01-01

61

Comparison of elderly people's technique in using two dry powder inhalers to deliver zanamivir: randomised controlled  

Microsoft Academic Search

Objective To determine whether elderly people can learn to use the inhaler used to deliver zanamivir (Relenza Diskhaler) as effectively as the Turbohaler and to identify which aspects of inhaler technique are most problematic. Design Randomised, controlled, intervention study. Setting Wards for acute elderly care in a large district general hospital. Participants 73 patients who were unfamiliar with the use

Paul Diggory; Christophe Fernandez; Amanda Humphrey; Valerie Jones; Maeve Murphy

2001-01-01

62

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

PubMed

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

63

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

64

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

NASA Technical Reports Server (NTRS)

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

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

2003-01-01

65

Preparation for intermetallic powders of Cu-Sn and Cu-Ni-Sn systems via solid-liquid reaction milling technique  

Microsoft Academic Search

The Cu-Sn binary intermetallic powders were obtained via a patented reaction ball milling technique. The Sn melt reacted with the solid-state Cu during the milling process at different temperatures for different intervals. Two kinds of binary intermetallics were obtained. For 12 h, Cu6Sn5 was prepared by milling Sn melt at 573 K while Cu3Sn by milling Sn melt at 773

CHEN Ding; WU Wei; CHEN Zhen-hua; FU Ding-fa

2007-01-01

66

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

67

The efficiency of universal techniques of atomic emission spectrography and spark source mass spectrography for the analysis of non-conducting powders  

NASA Astrophysics Data System (ADS)

Two semi-quantitative universal techniques for the analysis of very different non-conducting powdered materials were compared with regard to matrix influences on the reliability of the analytical results. One of these techniques is based on atomic emission spectrography (AES) and was proposed by K ROONEN and V ADER[4] several years ago. The other one is based on spark sources mass spectrograpny (SSMS) and has been developed in our laboratory more recently. To evaluate matrix effects objectively, a "total factor of variation". Vtot, was calculated as the antilogarithm of the standard deviation of the logarithms of analytical results over all matrices. The factor was compared by statistical analysis of variance to an analogous factor vrep, estimated in each case from a set of replicate determinations in one matrix and thus representing the precision of the technique. The results show that in the case of the SSMS technique vtot varies from 1.6 to 1.9 and only sometimes exceeds vrep slightly (probability P = 0.95). On the other hand for the AES procedure, vtot varies from 1.4 to 2.3 and always exceeds vrep, with a high significance ( P > 0.99). However, precision is higher in AES. From the results, the conclusion is drawn that SSMS is more suitable for elaboration of universal techniques, in the case of non-conducting powders just as in the case of compact metals.

Ehrlich, G.; Stahlberg, U.; Scholze, H.

68

Evaluation of a dry ball-milling technique as a method for mixing boron carbide and carbon nanotube powders  

Microsoft Academic Search

To evaluate the mixing effectiveness of dry ball-milling, multi-walled carbon nanotubes were ball-milled with boron carbide powder, and the resulting mixtures were hot pressed to consolidated tiles. Density, hardness, Young's modulus, and fracture strength of the tiles were measured; all decreased with increasing nanotube content. Microscopic examination revealed that the nanotubes were present in the tiles as micron-sized-and-larger agglomerates. It

R. H. Woodman; B. R. Klotz; R. J. Dowding

2005-01-01

69

Surface Corrosion of Ti–16Si–4B Powder Alloy Implanted With Nitrogen by Plasma-Based Technique  

Microsoft Academic Search

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

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

2011-01-01

70

Metal Powders (Metall Pulver).  

National Technical Information Service (NTIS)

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

1986-01-01

71

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

72

Development of Dry Powder Inhalers  

Microsoft Academic Search

Development of dry powder inhalers involves powder recrystallization, formulation, dispersion, delivery, and deposition of the therapeutic agent in different regions of the airways in prophylaxis\\/ treatment\\/ diagnosis of pulmonary and systemic disorders. Conventional powder production by crystallization and milling has many limitations resulting into development of alternative techniques to overcome the problems. In the last decade many patents have been

Mahavir B. Chougule; Bijay K. Padhi; Kaustubh A. Jinturkar; Ambikanandan Misra

2007-01-01

73

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

NASA Technical Reports Server (NTRS)

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

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

1991-01-01

74

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

NASA Astrophysics Data System (ADS)

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

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

2002-03-01

75

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

76

Determination of protein in milk powder using 2-sulfophenylazo-rhodanine as a probe by the enhanced resonance Rayleigh light-scattering technique.  

PubMed

In this paper, the interaction between 2-sulfophenylazo-rhodanine and protein was investigated by Rayleigh light-scattering technique. Based on this, a novel method for the determination of protein was developed. The effects of different conditions, such as acidity and media, were investigated thoroughly, and the optimum conditions were confirmed. Bis(2-ethylhexyl)sulfosuccinate (AOT) microemulsion, which is introduced into the protein determination, markedly increased the sensitivity of the system by changing the microenvironment. In pH 2.80 Britton-Robinson buffer solution in the presence of AOT microemulsion, the detection limits of bovine serum albumin, human serum albumin, ovalbumin, and gamma-globulin are 5.4, 4.5, 9.8, and 10.1 ng/mL, respectively. The method developed in this paper has been applied to the determination of protein in milk powder with satisfactory results. PMID:17042187

Wei, Qin; Li, Yan; Dong, Wenying; Du, Bin

2006-01-01

77

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

78

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

PubMed Central

Accurate characterization of the physicochemical properties of aerosols generated for inhalation toxicology studies is essential for obtaining meaningful results. Great emphasis must also be placed on characterizing particle properties of materials as administered in inhalation studies. Thus, research is needed to identify a suite of techniques capable of characterizing the multiple particle properties (i.e., size, mass, surface area, number) of a material that may influence toxicity. The purpose of this study was to characterize the morphology and investigate the size distribution of a model toxicant, beryllium. Beryllium metal, oxides, and alloy particles were aerodynamically size-separated using an aerosol cyclone, imaged dry using scanning electron microscopy (SEM), then characterized using phase contrast microscopy (PCM), a liquid suspension particle counter (LPC), and computer-controlled SEM (CCSEM). Beryllium metal powder was compact with smaller sub-micrometer size particles attached to the surface of larger particles, whereas the beryllium oxides and alloy particles were clusters of primary particles. As expected, the geometric mean (GM) diameter of metal powder determined using PCM decreased with aerodynamic size, but when suspended in liquid for LPC or CCSEM analysis, the GM diameter decreased by a factor of two (p < 0.001). This observation suggested that the smaller submicrometer size particles attached to the surface of larger particles and/or particle agglomerates detach in liquid, thereby shifting the particle size distribution downward. The GM diameters of the oxide materials were similar regardless of sizing technique, but observed differences were generally significant (p < 0.001). For oxides, aerodynamic cluster size will dictate deposition in the lung, but primary particle size may influence biological activity. The GM diameter of alloy particles determined using PCM became smaller with decreasing aerodynamic size fraction; however, when suspended in liquid for CCSEM and LPC analyses, GM particle size decreased by a factor of two (p < 0.001) suggesting that alloy particles detach in liquid. Detachment of particles in liquid could have significance for the expected versus actual size (and number) distribution of aerosol delivered to an exposure subject. Thus, a suite of complimentary analytical techniques may be necessary for estimating size distribution. Consideration should be given to thoroughly understanding the influence of any liquid vehicle which may alter the expected aerosol size distribution.

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

2007-01-01

79

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

PubMed

Accurate characterization of the physicochemical properties of aerosols generated for inhalation toxicology studies is essential for obtaining meaningful results. Great emphasis must also be placed on characterizing particle properties of materials as administered in inhalation studies. Thus, research is needed to identify a suite of techniques capable of characterizing the multiple particle properties (i.e., size, mass, surface area, number) of a material that may influence toxicity. The purpose of this study was to characterize the morphology and investigate the size distribution of a model toxicant, beryllium. Beryllium metal, oxides, and alloy particles were aerodynamically size-separated using an aerosol cyclone, imaged dry using scanning electron microscopy (SEM), then characterized using phase contrast microscopy (PCM), a liquid suspension particle counter (LPC), and computer-controlled SEM (CCSEM). Beryllium metal powder was compact with smaller sub-micrometer size particles attached to the surface of larger particles, whereas the beryllium oxides and alloy particles were clusters of primary particles. As expected, the geometric mean (GM) diameter of metal powder determined using PCM decreased with aerodynamic size, but when suspended in liquid for LPC or CCSEM analysis, the GM diameter decreased by a factor of two (p < 0.001). This observation suggested that the smaller submicrometer size particles attached to the surface of larger particles and/or particle agglomerates detach in liquid, thereby shifting the particle size distribution downward. The GM diameters of the oxide materials were similar regardless of sizing technique, but observed differences were generally significant (p < 0.001). For oxides, aerodynamic cluster size will dictate deposition in the lung, but primary particle size may influence biological activity. The GM diameter of alloy particles determined using PCM became smaller with decreasing aerodynamic size fraction; however, when suspended in liquid for CCSEM and LPC analyses, GM particle size decreased by a factor of two (p < 0.001) suggesting that alloy particles detach in liquid. Detachment of particles in liquid could have significance for the expected versus actual size (and number) distribution of aerosol delivered to an exposure subject. Thus, a suite of complimentary analytical techniques may be necessary for estimating size distribution. Consideration should be given to thoroughly understanding the influence of any liquid vehicle which may alter the expected aerosol size distribution. PMID:17328812

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

2007-01-01

80

Effects of dispersion technique and component ratio on densification and microstructure of multi-component Cu-based metal powder in direct laser sintering  

Microsoft Academic Search

A multi-component Cu-based metal powder, which consisted of a mixture of Cu, CuSn, and CuP, was developed for direct metal laser sintering (DMLS). The effects of powder characteristics such as particle shape, particle size and its distribution, and dispersion uniformity on the sintering behavior were studied. It is found that using a homogeneous powder mixture produced by ball mixing coarse

Dongdong Gu; Yifu Shen

2007-01-01

81

High Performance Powder Metallurgy Aluminum Alloys: An Overview.  

National Technical Information Service (NTIS)

The historic development of aluminum powder metallurgy dates back to the early 1900s with initial flake powder production and has matured to the present day production of viable aerospace alloys. Primary powder production and processing techniques, such a...

M. J. Koczak M. K. Premkumar

1989-01-01

82

High Performance Powder Metallurgy Aluminum Alloys - an Overview.  

National Technical Information Service (NTIS)

The historic development of aluminum powder metallurgy dates back to the early 1900's with initial flake powder production and has matured to the present day production of viable aerospace alloys. Primary powder production and processing techniques, such ...

M. J. Koczak M. K. Premkumar

1989-01-01

83

Magnetic and dielectric interactions in nano zinc ferrite powder: Prepared by self-sustainable propellant chemistry technique  

NASA Astrophysics Data System (ADS)

The structural, magnetic and dielectric properties of nano zinc ferrite prepared by the propellant chemistry technique are studied. The PXRD measurement at room temperature reveal that the compound is in cubic spinel phase, belong to the space group Fd-3m. The unit cell parameters have been estimated from Rietveld refinement. The calculated force constants from FTIR spectrum corresponding to octahedral and tetrahedral sites at 375 and 542 cm-1 are 6.61×102 and 3.77×102 N m-1 respectively; these values are slightly higher compared to the other ferrite systems. Magnetic hysteresis and EPR spectra show superparamagnetic property nearly to room temperature due to comparison values between magnetic anisotropy energy and the thermal energy. The calculated values of saturation magnetization, remenant magnetization, coercive field and magnetic moment supports for the existence of multi domain particles in the sample. The temperature dependent magnetic field shows the spin freezing state at 30 K and the blocking temperature at above room temperature. The frequency dependent dielectric interactions show the variation of dielectric constant, dielectric loss and impedance as similar to other ferrite systems. The AC conductivity in the prepared sample is due to the presence of electrons, holes and polarons. The synthesized material is suitable for nano-electronics and biomedical applications.

Daruka Prasad, B.; Nagabhushana, H.; Thyagarajan, K.; Nagabhushana, B. M.; Jnaneshwara, D. M.; Sharma, S. C.; Shivakumara, C.; Gopal, N. O.; Ke, Shyue-Chu; Chakradhar, R. P. S.

2014-05-01

84

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

85

Powder diffraction.  

National Technical Information Service (NTIS)

the importance of x-ray powder diffraction as an analytical tool for phase identification of materials was first pointed out by Debye and Scherrer in Germany and, quite independently, by Hull in the US. Three distinct periods of evolution lead to ubiquito...

M. Hart

1995-01-01

86

Powder diffraction  

SciTech Connect

the importance of x-ray powder diffraction as an analytical tool for phase identification of materials was first pointed out by Debye and Scherrer in Germany and, quite independently, by Hull in the US. Three distinct periods of evolution lead to ubiquitous application in many fields of science and technology. In the first period, until the mid-1940`s, applications were and developed covering broad categories of materials including inorganic materials, minerals, ceramics, metals, alloys, organic materials and polymers. During this formative period, the concept of quantitative phase analysis was demonstrated. In the second period there followed the blossoming of technology and commercial instruments became widely used. The history is well summarized by Parrish and by Langford and Loueer. By 1980 there were probably 10,000 powder diffractometers in routine use, making it the most widely used of all x-ray crystallographic instruments. In the third, present, period data bases became firmly established and sophisticated pattern fitting and recognition software made many aspects of powder diffraction analysis routine. High resolution, tunable powder diffractometers were developed at sources of synchrotron radiation. The tunability of the spectrum made it possible to exploit all the subtleties of x-ray spectroscopy in diffraction experiments.

Hart, M.

1995-12-31

87

A novel approach to synthesis of nanosize MgAl 2O 4 spinel powder through sol–gel citrate technique and subsequent heat treatment  

Microsoft Academic Search

This paper summarizes a study on the influence of heat-treatment atmosphere in synthesis of nanosize MgAl2O4 spinel powder employing sol–gel citrate route. Based on measurement of BET specific surface area, crystallite size, simultaneous thermal analysis, and microscopic observation, it was clarified that the argon atmosphere used for heat treatment of precursor reduced the particle size of synthesized ceramic powder significantly.

Ali Saberi; Farhad Golestani-Fard; Monika Willert-Porada; Zahra Negahdari; Christian Liebscher; Benjamin Gossler

2009-01-01

88

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

89

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

90

Preparation and characterization of Co 2+-doped Y 3Al 5O 12 nano-crystal powders by sol-gel technique  

NASA Astrophysics Data System (ADS)

Co 2+-doped Y 3Al 5O 12 (Co 2+:YAG) nanocrystalline powder sample was obtained by sol-gel method. The gel with the composition of CoO-Y 2O 3-Al 2O 3 was prepared from nitrates of yttrium, aluminum, cobalt and citric acid, and was heat-treated at temperatures ranging from 400 to 1000°C. The heated powder samples at different temperatures were characterized by X-ray diffraction analysis (XRD), transmission electron microscope (TEM), infrared spectra (IR) and emission spectra. Results showed that when the gel was heat-treated at 800°C, YAG nanocrystals with sizes 30-70 nm were formed. The emission spectrum of the heat-treated powders is identical to that of tetrahedral Co 2+ ions, which shows that Co 2+ ions are embedded in the lattice sites of YAG nanocrystals and are coordinated with four oxygens.

Sun, Zhihong; Yuan, Duorong; Duan, Xiulan; Wei, Xuecheng; Sun, Haiqing; Luan, Caina; Wang, Zengmei; Shi, Xuzhong; Xu, Dong; Lv, Mengkai

2004-01-01

91

Preparation and characterization of Co 2+-doped LiAl 5O 8 nano-crystal powders by sol–gel technique  

Microsoft Academic Search

Co2+-doped LiAl5O8 (Co2+:LAO) nanocrystalline powder sample was obtained by sol–gel method. The gel with the composition of CoO–Li2O–Al2O3 was prepared from lithium acetate, nitrates of aluminum and cobalt, citric acid, and was heat-treated at temperatures from 500 to 1000°C. The heated powder samples at different temperatures were characterized by differential thermal and thermogravimetric analysis (DTA\\/TG), X-ray diffraction analysis (XRD), transmission

Dongying Pan; Duorong Yuan; Haiqing Sun; Xiulan Duan; Caina Luan; Shiyi Guo; Zhanfa Li; Lihua Wang

2006-01-01

92

Preparation and characterization of Co 2+-doped Y 3Al 5O 12 nano-crystal powders by sol–gel technique  

Microsoft Academic Search

Co2+-doped Y3Al5O12 (Co2+:YAG) nanocrystalline powder sample was obtained by sol–gel method. The gel with the composition of CoO–Y2O3–Al2O3 was prepared from nitrates of yttrium, aluminum, cobalt and citric acid, and was heat-treated at temperatures ranging from 400 to 1000°C. The heated powder samples at different temperatures were characterized by X-ray diffraction analysis (XRD), transmission electron microscope (TEM), infrared spectra (IR)

Zhihong Sun; Duorong Yuan; Xiulan Duan; Xuecheng Wei; Haiqing Sun; Caina Luan; Zengmei Wang; Xuzhong Shi; Dong Xu; Mengkai Lv

2004-01-01

93

Ceramic Powders  

NASA Technical Reports Server (NTRS)

In developing its product line of specialty ceramic powders and related products for government and industrial customers, including companies in the oil, automotive, electronics and nuclear industries, Advanced Refractory Technologies sought technical assistance from NERAC, Inc. in specific areas of ceramic materials and silicon technology, and for assistance in identifying possible applications of these materials in government programs and in the automotive and electronics industry. NERAC conducted a computerized search of several data bases and provided extensive information in the subject areas requested. NERAC's assistance resulted in transfer of technologies that helped ART staff develop a unique method for manufacture of ceramic materials to precise customer specifications.

1984-01-01

94

PowderSolve – a complete package for crystal structure solution from powder diffraction patterns  

Microsoft Academic Search

Powder diffraction techniques are becoming increasingly popular as tools for the determination of crystal structures. The authors of this paper have developed a software package, named PowderSolve, to solve crystal structures from experi- mental powder diffraction patterns and have applied this package to solve the crystal structures of organic compounds with up to 18 variable degrees of freedom (defined in

G. E. Engel; S. Wilke; O. König; K. D. M. Harris; F. J. J. Leusen

1999-01-01

95

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

96

Steam distillation-solvent extraction, a selective sample enrichment technique for the gas chromatographic-electron-capture detection of organochlorine compounds in milk powder and other milk products  

Microsoft Academic Search

The application of a simultaneous water steam distillation-organic solvent extraction (SDE) method for the GC-electron-capture detection of hexachlorobenzene, ?-hexachlorocyclohexane (?-HCH), ?-HCH, cis-heptachlorepoxide, 2,4?-DDE, 4,4?-DDE, dieldrin, 2,4?-DDT and 4,4?DDT in milk powder and other milk products is described. The SDE apparatus was a newly designed modification of the apparatus of Likens and Nickerson and Godefroot and co-workers and light petroleum was

Gerda Filek; Marcello Bergamini; Wolfgang Lindner

1995-01-01

97

Taguchi analysis of surface modification technique using W-Cu powder metallurgy sintered tools in EDM and characterization of the deposited layer  

Microsoft Academic Search

The present study describes an experimental research on surface modification during electrical discharge machining (EDM) by\\u000a depositing a hard layer over the work surface of C-40 grade plain carbon steel using specially prepared powder metallurgy\\u000a compact tools. The investigated process parameters were composition, compaction pressure, sintering temperature, pulse on-time,\\u000a peak–current setting, and duty factor. Measurements of deposited layer thickness, mass

Promod K. Patowari; Partha Saha; Prasanta K. Mishra

2011-01-01

98

Synthesis of boron nitride powders  

NASA Astrophysics Data System (ADS)

In the materials science community there is much interest in the development of new, efficient approaches for preparing ceramic powders having properties or performance characteristics not found with powders produced by traditional metallurgical synthesis methods. In this regard, aerosol-based syntheses are finding general acceptance for the preparation of non-metal and metal oxide powders. In contrast, much less effort has been given to aerosol-type syntheses for non-oxide powders despite potentially useful benefits. This dissertation describes the application of two chemical systems in aerosol assisted vapor phase synthesis (AAVS) for the preparation of spherical morphology boron oxynitride, BNxOy, powders that are subsequently converted to spherical morphology boron nitride in a second nitridation step. Chapter 1 describes the AAVS synthesis of BNxOy powders using a reaction of an aqueous boric acid containing aerosol with ammonia at 1000°C. The effect of reactor tube material, total gas flow rate, ammonia concentration, boric acid concentration, and urea addition to the boric acid aerosol on the percent oxygen composition is described. The resulting BNxOy powders contain significant amounts of oxygen that require replacement in a second stage nitridation reaction at elevated temperature under ammonia. The influences of the reaction temperature profile, crucible geometry and transformation additive on final oxygen composition and powder crystallinity are described. Chapter 2 outlines the formation of BNxOy powders from an AAVS reaction between the boron precursor (MeO)3B and ammonia. The formation of the powders is studied as a function of total gas flow rate and ammonia concentration. In all cases the resulting powders contain lower levels of oxygen compared to powders produced from aqueous boric acid aerosols. The conversion of the BNxOy powders in the second stage nitridation reaction with ammonia is examined as a function of crucible geometry, temperature profile and ammonia flow rate. In support of this process, the molecular reaction between (MeO)3B and NH3 was reexamined. The adduct, (MeO)3B·NH3, was isolated and its molecular structure determined by single crystal X-ray diffraction techniques. The results of these studies provide guidance for more detailed studies that should result in industrial scale synthesis of spherical morphology BN which currently is not formed by standard metallurgical syntheses. This new material has potential applications in several areas including the formation of BN loaded organic polymer composites.

Dreissig, Dirk Horst

2002-09-01

99

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) [Greensburg, PA

1988-01-01

100

Powder treatment process  

DOEpatents

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

Weyand, J.D.

1988-02-09

101

Mechanics of Powder Plastic Powder Compacts.  

National Technical Information Service (NTIS)

Colloidal Isopressing is a new method for the shaping of ceramic components from powder suspensions in a rapid and effective manner. Colloidal Isopressing starts with a slurry containing a relatively low volume fraction of powder, where the particles weak...

F. F. Lange

2001-01-01

102

POWDERS FOR EXTINGUISHING FIRES  

Microsoft Academic Search

The development of a powder suitable for extinguishing fires of burning ; U, Pu, or Th is described. The powder consists of a mixture of powdered ; inorganic chlorides and\\/or fluorides inert towards the bunning metal. The ; mixture has a melting point below the melting point of the burning metal such ; that fusion of the powder takes place

Cope

1963-01-01

103

Resin-Powder Dispenser  

NASA Technical Reports Server (NTRS)

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

Standfield, Clarence E.

1994-01-01

104

Preparation of titanium diboride powder  

SciTech Connect

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, J.; Bamberger, C.E.

1985-03-05

105

Preparing Copper Powder from Cemented Copper.  

National Technical Information Service (NTIS)

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

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

1971-01-01

106

Dispersion Hardened Titanium Alloys by Powder Metallurgy.  

National Technical Information Service (NTIS)

The characteristics and applications of titanium alloys for structural purposes are discussed. A method of producing dispersion hardened titanium alloys through powder metallurgical techniques is described. An electron beam splatting furnace designed for ...

S. Pattanaik K. G. Gopinathan V. S. Arunachalam

1974-01-01

107

Surface Modification of EDMed Surface with Powder Mixed Fluid  

Microsoft Academic Search

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

Y. Uno; A. Okada; S. Cetin

108

Plasma spheroidization of nickel powders in a plasma reactor  

Microsoft Academic Search

Thermal spray coatings of surfaces with metal, alloy and ceramic materials for protection against corrosion, erosion and wear is an intense field of research. The technique involves injection of the powder into a plasma flame, melting, acceleration of the powder particles, imp act and bonding with the substrate. Feed- stock powders of metals, alloys and ceramics for thermal spray applications

G SHANMUGAVELAYUTHAM; V SELVARAJAN

2004-01-01

109

Rapidly solidified prealloyed powders by laser spin atomization  

Microsoft Academic Search

A new technique, termed laser spin atomization, for the production of rapidly solidified prealloyed powders is described. The results of experiments involving the production of powders of two alloys, one based on Ni, the other on Ti, are presented. The powders have been characterized using light optical metallography, scanning electron microscopy, energy dispersive X-ray spectroscopy, and Auger elec-tron spectroscopy, and

D. G. Konitzer; K. W. Walters; E. L. Heiser; H. L. Fraser

1984-01-01

110

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

111

Ceramic powder compaction.  

National Technical Information Service (NTIS)

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 experime...

S. J. Glass K. G. Ewsuk F. M. Mahoney

1995-01-01

112

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

Microsoft Academic Search

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

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

2007-01-01

113

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

114

Thoria powder process development (LWBR Development Program)  

SciTech Connect

The development program to identify the critical parameters for the process of converting thorium nitrate solution into thoria powder is described. Thorium oxalate hexahydrate is precipitated from the reaction of thorium nitrate solution with oxalic acid. The resulting thorium oxalate hexahydrate slurry is filter pressed into a cake which is air calcined to form thoria powder. Changes in the critical processing parameters such as free nitric acid content of the thorium nitrate solution, precipitation temperature, and calcining temperature altered the thoria powder characteristics, and thus its capability for being fabricated into fuel pellets. The objective of the powder preparation effort was to obtain thoria powders which could be formed by conventional ceramic fabrication techniques into thoria and thoria-urania pellets of high density and high integrity having a nearly uniform large grain structure.

Hutchison, C.R.; Lloyd, R.

1979-10-01

115

Microemulsion Synthesis of Nanoparticle PZT Powder  

Microsoft Academic Search

Nanocrystalline lead zirconate titanate (PZT) powders have been synthesized using microemulsion processing route. Microemulsion is one of the major processing techniques to synthesize a nanosize, homogenous, and almost agglomerate free ceramic powders. The ternary microemulsion system is consisted of cyclohexane as the oil phase, Triton X100 as the nonionic surfactant phase, and an aqueous phase containing 0.619 M Pb2+, 0.325

M. Amiriyan; Z. A. Nemati; M. S. Rahmanifar; S. Ramesh; S. Meenaloshini; R. Tolouei

2011-01-01

116

Stainless steel coatings sputter-deposited on tungsten carbide powder particles  

Microsoft Academic Search

The aim of this work was to study the feasibility of a sputtering technique to coat WC powder particles, regarding it as an alternative to the conventional mixture of powders. For such purpose, a stainless steel 304 (AISI) coating was sputter deposited on WC powder particles using a magnetron sputtering equipment specially developed to coat powder particles. The morphology of

C. M. Fernandes; V. M. Ferreira; A. M. R. Senos; M. T. Vieira

2003-01-01

117

Powders for magnetoabrasive machining  

Microsoft Academic Search

Conclusions On the basis of literature data an analysis is made of the abrasive power and magnetic properties of powders of various magnetoabrasive materials and of the degree of interaction between their magnetic and abrasive constituents. It is concluded that the greatest potentiality for MAP is shown by materials containing a refractory compound powder as their abrasive component and an

G. D. Nalivka; A. N. Stepanchuk; L. N. Tul'chinskii

1976-01-01

118

Aluminum powder applications  

Microsoft Academic Search

Aluminum powders have physical and metallurgical characteristics related to their method of manufacture that make them extremely important in a variety of applications. They can propel rockets, improve personal hygiene, increase computer reliability, refine exotic alloys, and reduce weight in the family sedan or the newest Air Force fighter. Powders formed into parts for structural and non-structural applications hold the

Gurganus

1995-01-01

119

Vacuum Powder Injector  

NASA Technical Reports Server (NTRS)

Method developed to provide uniform impregnation of bundles of carbon-fiber tow with low-solubility, high-melt-flow polymer powder materials to produce composite prepregs. Vacuum powder injector expands bundle of fiber tow, applies polymer to it, then compresses bundle to hold powder. System provides for control of amount of polymer on bundle. Crystallinity of polymer maintained by controlled melt on takeup system. All powder entrapped, and most collected for reuse. Process provides inexpensive and efficient method for making composite materials. Allows for coating of any bundle of fine fibers with powders. Shows high potential for making prepregs of improved materials and for preparation of high-temperature, high-modulus, reinforced thermoplastics.

Working, Dennis C.

1991-01-01

120

Ceramic powder synthesis in supercritical fluids  

SciTech Connect

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

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

1996-04-01

121

Transparent zinc sulfide processed from nanocrystalline powders  

NASA Astrophysics Data System (ADS)

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

Gao, De; Stefanik, Todd S.

2013-06-01

122

Compaction of Titanium Powders  

NASA Astrophysics Data System (ADS)

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

Gerdemann, Stephen J.; Jablonski, Paul D.

2011-05-01

123

Compaction of Titanium Powders  

SciTech Connect

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

Gerdemann, Stephen,J; Jablonski, Paul, J

2011-05-01

124

Sintering titanium powders  

SciTech Connect

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

Gerdemann, Stephen J.; Alman, David E.

2005-09-01

125

Superfast densification of nanocrystalline oxide powders by spark plasma sintering  

Microsoft Academic Search

Spark plasma sintering (SPS) is a newly discovered old technique which recently has been used for superfast densification\\u000a of ceramic powders. Simultaneous application of pulsed high dc current densities and load is the necessary condition for rapid\\u000a and full densification of ceramic powders by SPS. Commercial nanocrystalline magnesium oxide (nc-MgO) and yttrium aluminum\\u000a garnet (nc-YAG) powders were densified to optical

R. Chaim

2006-01-01

126

Plasma spheroidization of nickel powders in a plasma reactor  

Microsoft Academic Search

Thermal spray coatings of surfaces with metal, alloy and ceramic materials for protection against corrosion, erosion and wear\\u000a is an intense field of research. The technique involves injection of the powder into a plasma flame, melting, acceleration\\u000a of the powder particles, impact and bonding with the substrate. Feedstock powders of metals, alloys and ceramics for thermal\\u000a spray applications have to

G. Shanmugavelayutham; V. Selvarajan

2004-01-01

127

Rapidly solidified prealloyed powders by laser spin atomization  

Microsoft Academic Search

A new technique, termed laser spin atomization, for the production of rapidly solidified prealloyed powders is described.\\u000a The results of experiments involving the production of powders of two alloys, one based on Ni, the other on Ti, are presented.\\u000a The powders have been characterized using light optical metallography, scanning electron microscopy, energy dispersive X-ray\\u000a spectroscopy, and Auger elec-tron spectroscopy, and

D. G. Konitzer; K. W. Walters; E. L. Heiser; H. L. Fraser

1984-01-01

128

Mystery Powder Investigation  

NSDL National Science Digital Library

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

Hallettnjuguna, Rachel

2012-07-27

129

Combustibility of titanium powders  

NASA Technical Reports Server (NTRS)

The combustion of compact samples was studied; the mechanism of autoignition is defined. Several studies are made of the combustibility of titanium using 50 samples. The data provide a clear idea of the combustibility of titanium powders.

Popov, Ye. I.; Poyarkov, V. G.; Finayev, Yu. A.

1989-01-01

130

Some Candidate Louse Powders.  

National Technical Information Service (NTIS)

During the past several years, several new candidate louse powders have been developed through a cooperative program between the U. S. Department of Agriculture and the Department of Defense. These compounds include Abate, Cidial, Mobam, Carbaryl and GS-1...

M. M. Cole P. H. Clark R. H. Grothaus

1973-01-01

131

Gelcasting superalloy powders  

SciTech Connect

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

Janney, M.A.

1995-12-31

132

Hepagene (PowderJect).  

PubMed

Celltech Group (formerly Medeva) developed Hepagene, a recombinant polyvalent vaccine with potential activity against hepatitis B virus infections [353474]. In September 2000, PowderJect acquired the product as part of its acquisition of Celltech's vaccine manufacturing business [381557]. In July 2001, PowderJect reported that evaluation was nearing completion. At this time, the company expected to launch the vaccine in the coming months [443490]. Hepagene is a polyvalent vaccine with S, pre-S1 and pre-S2 hepatitis B epitopes forming the basis of its antigenicity. Additionally, these surface markers have been glycosylated in order to resemble the live virus more closely [254780]. By June 2000, Celltech and PowderJect were evaluating Hepagene, utilizing PowderJect's needle-less injection technology [379536]. In December 1999, Lehman Brothers predicted that the product had a 50% chance of reaching the treatment (rather than prevention) market, with potential peak sales of US $600 million [352078]. PMID:12186276

Jones, Taff

2002-07-01

133

Textured powder wires  

US Patent & Trademark Office Database

A method for fabricating a wire from textured powder includes compressing a powder comprising a plurality of particles into a ribbon. The method further includes encasing the ribbon between two foil sheets to create a sheet of encased ribbon. The method additionally includes rolling the encased ribbon into a substantially cylindrical undrawn wire. The method further includes drawing the undrawn wire to create a substantially cylindrical wire having a diameter less than a diameter of the substantially cylindrical undrawn wire.

2013-11-26

134

Powder Core Dielectric Waveguides  

Microsoft Academic Search

A powder-filled surface of a led groove in the teflon substrate has been demonstrated as a dielectric waveguide at 94 GHz. Guide wavelengths measured for combinations of guide dimensions and powders agree within 10% of values predicted by Marcatili 's approximate theory. Attenuation constants of 0.2 to 0.3 dB\\/cm were measured for barium tetra-titanate.

W. M. Bruno; W. B. Bridges

1984-01-01

135

Consolidation of nanostructured metal powders by rapid forging: Processing, modeling, and subsequent mechanical behavior  

Microsoft Academic Search

Fe-10Cu powders containing 20-nm grains were produced by attritor milling of elemental powders in argon. A rapid powder forging\\u000a technique was developed to consolidate the powders into fully dense compacts while maintaining nanoscale grain sizes. Grain\\u000a growth during the consolidation was controlled by reducing the time of exposure at elevated temperature to a few minutes or\\u000a less, a technique which

G. R. Shaik; W. W. Milligan

1997-01-01

136

Consolidation of nanostructured metal powders by rapid forging: Processing, modeling, and subsequent mechanical behavior  

Microsoft Academic Search

Fe?10Cu powders containing 20-nm grains were produced by attritor milling of elemental powders in argon. A rapid powder forging\\u000a technique was developed to consolidate the powders into fully dense compacts while maintaining nanoscale grain sizes. Grain\\u000a growth during the consolidation was controlled by reducing the time of exposure at elevated temperature to a few minutes or\\u000a less, a technique which

G. R. Shaik; W. W. Milligan

1997-01-01

137

Microstructural evaluation of as-solidified and heat treated. gamma. -TiAl based powders  

Microsoft Academic Search

Powders with nominal compositions (in atomic %) Ti-48Al and Ti-48Al-2Nb-2Cr were prepared by the plasma rotating electrode process (PREP) and gas atomization (GA) techniques. As-solidified and heat treated (1000° C\\/3 hr) powder samples were examined by metallography, SEM, X-ray diffraction, and TEM. The microstructures of the powders were characterized as a function of atomization technique, alloy content, powder particle size

G. E. Fuchs; S. Z. Hayden

1991-01-01

138

Shock-Wave Consolidation of Nanostructured Bismuth Telluride Powders  

NASA Astrophysics Data System (ADS)

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

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

2012-06-01

139

Coal Powder Beneficiation by Dry Hgms Process--American Coal  

Microsoft Academic Search

A method for the beneficiation of American coal powder without using a liquid dispersion medium was investigated. In this method the coal powder is fluidized in a high gradient magnetic field region. Processing American coal by this technique resulted in a performance level yield of 80 percent and ash reduction rate of 30 percent, which were rather good results. Also,

T. Oda; T. Takahashi; T. Uebayashi; S. Masuda

1987-01-01

140

Dispersion of carbon nanotubes (CNTs) in aluminum powder  

Microsoft Academic Search

In the present work, we use mechanical alloying (MA) for the first time to generate a homogenous distribution of 2wt% CNT within Al powders. The effect of milling time (up to 48h) on the morphological development of the powders and dispersion of CNTs was investigated. The results show that the technique is effective in dispersing the nanotubes within the soft

A. Esawi; K. Morsi

2007-01-01

141

Production of Fine Metallic Powders by Hybrid Atomization Process  

Microsoft Academic Search

Hybrid Atomization is a recently developed powder-making process that combines effectively free-fall gas atomization and centrifugal atomization. This technique can produce very fine spherical powders with mean diameters of around 10 micrometers, and in high yields. The present report discusses the concept and basic principles of hybrid atomization. Process experiments were carried out and the optimal processing conditions were obtained.

Kazumi Minagawa; Yunzhong Liu; Hideki Kakisawa; Kohmei Halada

2003-01-01

142

The introduction of powder blasting for sensor and microsystem applications  

Microsoft Academic Search

We introduce powder blasting using a pressurised nozzle and a metallic mask as a new promising technology for microsystem fabrication. We study basic parameters of this powder blasting erosion process as well as mask-geometry effects on the erosion rate. We demonstrate the application potential of this technique in three important fields of microsystems research: (i) the realisation of microfluidic chips

E. Belloy; S. Thurre; E. Walckiers; A. Sayah; M. A. M Gijs

2000-01-01

143

Microwave absorption properties of composite powders with low density  

Microsoft Academic Search

The composites of barium ferrite coated on hollow ceramic microspheres were prepared using sol–gel technique. The crystal structure, morphology and microwave absorption properties of composite powders with different weight ratio of microspheres were studied with XRD, EDS, FESEM and vector network analyzer. The results show that the microwave absorption properties of composite powders are greatly improved. The maximum microwave loss

Guohong Mu; Haigen Shen; Jianxun Qiu; Mingyuan Gu

2006-01-01

144

A review on the continuous blending of powders  

Microsoft Academic Search

This review traces the underlying theory and practice of continuous powder blending to provide a foundation for its development. Apart from reviewing the experimental studies reported in literature, some of the monitoring techniques used in blending research with applications in continuous blending also are considered. This review attempts to identify the synergy that can be realized by studying powder behavior

Lakshman Pernenkil; Charles L. Cooney

2006-01-01

145

Applications of Thermal Mechanical Compression Tests in Food Powder Analysis  

Microsoft Academic Search

A new Thermal Mechanical Compression Test (TMCT) was applied for glass-rubber transition and melting analyses of food powders and crystals. The TMCT technique measures the phase change of a material based on mechanical changes during the transition. Whey, honey, and apple juice powders were analyzed for their glass-rubber transition temperatures. Sucrose and glucose monohydrate crystals were analyzed for their melting

P. Boonyai; B. Bhandari; T. Howes

2006-01-01

146

TiNi synthesis from elemental powder components  

Microsoft Academic Search

Commercially, the shape memory alloy TiNi is produced by either vacuum induction melting or by vacuum arc remelting of the pure metal ingots. Powder metallurgy techniques provide an alternative fabrication route but problems arise achieving chemical homogeneity. In this study TiNi compacts were cold pressed from the blended elemental powders and sintered in vacuum for varying times at temperatures from

Janet C. Hey; A. Peter Jardine

1994-01-01

147

Screening mail for powders using terahertz technology  

Microsoft Academic Search

Following the 2001 Anthrax letter attacks in the USA, there has been a continuing interest in techniques that can detect or identify so-called 'white powder' concealed in envelopes. Electromagnetic waves (wavelengths 100-500 mum) in the terahertz frequency range penetrate paper and have short enough wavelengths to provide good resolution images; some materials also have spectroscopic signatures in the terahertz region.

Mike Kemp

2011-01-01

148

Characterization of Powder Flowability for Die Filling  

Microsoft Academic Search

Inter-tablet variations in composition and weight depend on the flowability of pharmaceutical formulations. In this study, the concept of critical filling speed, which was proposed to characterize the flowability with special application to die filling, is evaluated and compared with other powder flow characterization techniques. It has been found that the critical filling speed provides a consistent gauge of the

Chuan-Yu Wu; Brian Armstrong; Nikolaus Vlachos

2012-01-01

149

Ceramic powder synthesis by spray pyrolysis  

Microsoft Academic Search

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

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

1993-01-01

150

Strength enhancement process for prealloyed powder superalloys  

NASA Technical Reports Server (NTRS)

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

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

1977-01-01

151

Intergrain interactions in nanocomposite Fe-Pt powders  

SciTech Connect

The structure and magnetic properties of nanocomposite Fe{sub 100-x}Pt{sub x} (x=40, 50, and 60) powders prepared by mechanical alloying followed by annealing are investigated. Various combinations of phases, away from thermodynamic equilibrium, were obtained using this technique. Remanence curves and magnetic force microscopy data were used to provide insight into the nature of intergrain interactions in such powders. The analysis points to strong intergrain coupling in the Fe{sub 100-x}Pt{sub x} powders. An additional small magnetostatic contribution can be observed for the Pt-rich powders.

Lyubina, Julia; Khlopkov, Kirill; Gutfleisch, Oliver; Mueller, Karl-Hartmut; Schultz, Ludwig [IFW Dresden, Institute for Metallic Materials, P.O. Box 270016, D-01171 Dresden (Germany)

2006-04-15

152

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

153

Freeze Drying: Potential for Powdered Nanoparticulate Product  

Microsoft Academic Search

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

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

2010-01-01

154

Iowa Powder Atomization Technologies  

ScienceCinema

The same atomization effect seen in a fuel injector is being applied to titanium metal resulting in fine titanium powders that are less than half the width of a human hair. Titanium melts above 3,000°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

2013-03-01

155

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

156

Powder towpreg process development  

NASA Technical Reports Server (NTRS)

The process for dry powder impregnation of carbon fiber tows being developed at LaRC overcomes many of the difficulties associated with melt, solution, and slurry prepregging. In the process, fluidized powder is deposited on spread tow bundles and fused to the fibers by radiant heating. Impregnated tows have been produced for preform, weaving, and composite materials applications. Design and operating data correlations were developed for scale up of the process to commercial operation. Bench scale single tow experiments at tow speeds up to 50 cm/sec have demonstrated that the process can be controlled to produce weavable towpreg. Samples were woven and molded into preform material of good quality.

Baucom, Robert M.; Marchello, Joseph M.

1991-01-01

157

Powder magnetoresistance (invited)  

NASA Astrophysics Data System (ADS)

Magnetoresistance observed in pressed powder compacts of half-metallic ferromagnetic oxides is reviewed. The main, isotropic negative magnetoresistance, which exceeds 50% in CrO2 at low temperature, is due to alignment of the the ferromagnetic moments of contiguous ferromagnetic grains. The effect is related to interparticle tunelling and shows hysteresis similar to that of the bulk magnetization. Spin-dependent Coulomb blocade observed in the smallest particles. There is also, an anisotropic magnetoresistance of up to 1% and a high-field increase in conductivity of order 1%/T in the powder compacts.

Coey, J. M. D.

1999-04-01

158

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

159

Magnetic powder filled polymers  

Microsoft Academic Search

The composite magnetic materials with commercial polymer matrix along with different magnetic fillers have been studied, with the aim of tailoring their properties. The measured magnetic parameters of the prepared samples have been compared by those calculated using a model in which the magnetic powder particles are surrounded by the thin layer of matrix material

Jozef Slama; Anna Gruskova; Ludovit Keszegh; Mojmir Kollar

1994-01-01

160

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

161

Sintering behaviour of piezoceramic powders prepared by conventional, ceramic and mechanical activation process  

Microsoft Academic Search

Conventional and mechanical activation techniques were used to prepare a soft PZT type piezoceramic material. The resulting powders exhibit micro and nanostructures, respectively as indicated by X-ray and electron microscopy. Average crystallite sizes of 1 ?m and 50 nm respectively were estimated for the powders. The sintered behavior of pressed samples from the two types of powders was investigated within

C. Miclea; C. Tanasoiu; A. Gheorghiu; C. F. Midea; V. Tanasoiu

2001-01-01

162

Powder compaction, sintering, and rolling of ultra high molecular weight polyethylene and its composites  

Microsoft Academic Search

The applicability of powder compaction and sintering techniques to the processing of ultra high molecular weight polyethylene (UHMWPE) powder is demonstrated. With proper processing procedure and type of UHMWPE powder, the mechanical properties obtained are nearly equivalent to those obtained by conventional melt processes. The properties were optimized by selection of a sintering temperature just above the melting point and

K. S. Han; J. F. Wallace; R. W. Truss; P. H. Geil

1981-01-01

163

Ultrasonic Characterization of Iron Powder Metallurgy Compacts during and after Compaction  

Microsoft Academic Search

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

Andrew Lerossignol Dawson; Jean François Bussière

1998-01-01

164

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

165

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

166

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

167

Optimized pulmonary gene transfection in mice by spray–freeze dried powder inhalation  

Microsoft Academic Search

Spray–freeze drying (SFD) is an attractive technique to prepare highly porous dry powders for inhalation. However, there have been few reports of its application to dry powder inhalers (DPIs). Therefore, in this study, we prepared dry plasmid DNA (pDNA) powders with different molecular ratios of chitosan to pDNA (N\\/P ratios) by SFD. All the pDNA powders were spherical and highly

Kohta Mohri; Tomoyuki Okuda; Asami Mori; Kazumi Danjo; Hirokazu Okamoto

2010-01-01

168

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

Microsoft Academic Search

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

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

1997-01-01

169

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

170

Synthesis of boron nitride powders  

Microsoft Academic Search

In the materials science community there is much interest in the development of new, efficient approaches for preparing ceramic powders having properties or performance characteristics not found with powders produced by traditional metallurgical synthesis methods. In this regard, aerosol-based syntheses are finding general acceptance for the preparation of non-metal and metal oxide powders. In contrast, much less effort has been

Dirk Horst Dreissig

2002-01-01

171

Ignition characteristics of plutonium powder  

Microsoft Academic Search

Two fires occurred recently in a vacuum cleaner used to pick up plutonium powder during brushing of plutonium. The plutonium powder was collected by a conventional canister vacuum cleaner passing directly into the clean bag which was changed daily and sent to Building 771 for recovery. Finely divided metal powder is known to be a potential fire and explosion hazard.

Musgrave

1971-01-01

172

Vacuum powder injector and method of impregnating fiber with powder  

NASA Technical Reports Server (NTRS)

A method and apparatus uniformly impregnate stranded material with dry powder such as low solubility, high melt flow polymer powder to produce, for example, composite prepregs. The stranded material is expanded in an impregnation chamber by an influx of air so that the powder, which may enter through the same inlet as the air, penetrates to the center of the stranded material. The stranded material then is contracted for holding the powder therein. The stranded material and powder may be pulled through the impregnation chamber in the same direction by vacuum. Larger particles of powder which do not fully penetrate the stranded material may be combed into the stranded material and powder which does not impregnate the stranded material may be collected and reused.

Working, Dennis C. (inventor)

1993-01-01

173

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

National Technical Information Service (NTIS)

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

N. J. Grant

1986-01-01

174

Advanced powder metallurgy aluminum alloys via rapid solidification technology  

NASA Technical Reports Server (NTRS)

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

Ray, R.

1984-01-01

175

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

176

Surface dose measurement using TLD powder extrapolation  

SciTech Connect

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

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

2006-10-01

177

Laser diffraction particle size analysis of powders  

SciTech Connect

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

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

1987-10-01

178

Bulk manufacture of YBCO powders by coprecipitation  

Microsoft Academic Search

This work presents an assessment of the coprecipitation technique for the reliable production of high-temperature superconducting (HTS) copper-oxide powders in quantities scaled up to 1 kg. This process affords precise control of cation stoichiometry (< 4% relative), occurs rapidly (almost instantaneously) and can be suitably developed for large-scale (e.g. tonne) manufacture of HTS materials. The process is based upon a

Atit Bhargava; Ian D. R. Mackinnon; Toru Yamashita; David Page

1995-01-01

179

Strength enhancement process for prealloyed powder superalloys  

NASA Technical Reports Server (NTRS)

A technique involving superplastic processing and high-pressure autoclaving was applied to a nickel-base prealloyed powder alloy. Tensile strengths as high as 2865 MN/sq m (415 ksi) at 480 C (900 F) were obtained with as-superplastically deformed material. Appropriate treatments yielding materials with high-temperature tensile and stress-rupture strengths (980 C (1800 F)) were also devised.

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

1977-01-01

180

Crack prevention in shock compaction of powders  

SciTech Connect

The occurrence of macro-cracks in compacts fabricated by shock compaction of powders is a severe problem preventing this consolidation technique from commercial applications. In this paper the sources of important failure types that typically occur in the cylindrical configuration i.e. radial, transverse, and spiral cracks and the Mach stem are described. Subsequently, solutions for their prevention are given supported by experimental results and/or computer simulations. Some conflicting requirements for obtaining bonded crack-free compacts are discussed.

Carton, E. P. [TNO Prins Maurits Laboratory, P.O. Box 45, 2280 AA, Rijswijk (Netherlands); Delft University of Technology, Laboratory for Applied Inorganic Chemistry, P.O. Box 5045, 2600 Georgia, Delft (Netherlands); Stuivinga, M.; Verbeek, H. J. [TNO Prins Maurits Laboratory, P.O. Box 45, 2280 AA, Rijswijk (Netherlands)

1998-07-10

181

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

Microsoft Academic Search

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

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

2008-01-01

182

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

183

Evaluation of powder metallurgy superalloy disk materials  

NASA Technical Reports Server (NTRS)

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

Evans, D. J.

1975-01-01

184

Microwave absorption properties of composite powders with low density  

NASA Astrophysics Data System (ADS)

The composites of barium ferrite coated on hollow ceramic microspheres were prepared using sol-gel technique. The crystal structure, morphology and microwave absorption properties of composite powders with different weight ratio of microspheres were studied with XRD, EDS, FESEM and vector network analyzer. The results show that the microwave absorption properties of composite powders are greatly improved. The maximum microwave loss of composite powders reaches 31 dB with an amount of 50 wt.% microspheres, and its density is only about 1.80 g/cm 3. The effect of hollow ceramic microspheres on the microwave absorption property is also discussed.

Mu, Guohong; Shen, Haigen; Qiu, Jianxun; Gu, Mingyuan

2006-12-01

185

Heats of immersion of titania powders in primer solutions  

NASA Technical Reports Server (NTRS)

The oxide layer present on titanium alloys can play an important role in determining the strength and durability of adhesive bonds. Here, three titania powders in different crystalline phases, rutile-R1, anatase-A1, and anatase-A2, are characterized by several techniques. These include microelectrophoresis, X-ray diffractometry, surface area pore volume analysis, X-ray photoelectron spectroscopy, and measurements of the heats of immersion. Of the three powders, R1 has the highest heat of immersion in water, while the interaction between water and A1 powder is low. Experimental data also suggest a specific preferential interaction of polyphenylquinoxaline with anatase.

Siriwardane, R.; Wightman, J. P.

1983-01-01

186

Spark-plasma-sintering (SPS) of nanostructured titanium carbonitride powders  

Microsoft Academic Search

Spark-plasma-sintering (SPS) compaction experiments of nanostructured titanium carbonitride powders have been performed at 1600°C and 1800°C (sintering time = 1min). The as-received nanostructured powders have been synthesized through rapid condensation from the gas-phase (high frequency plasma). The sintering results were compared with data obtained by various conventional sintering techniques such as pressureless sintering, gas pressure sintering, and hot pressing. The

P. Angerer; L. G. Yu; K. A. Khor; G. Korb; I. Zalite

2005-01-01

187

Infrared thermography of burn front propagation in heat powders  

SciTech Connect

Heat powders are consolidated into dense composites to form concentrated chemical heat sources. During the reaction, a high temperature burn front propagates through the composites. The burn front is preceded by a lower temperature thermal front which generates thermal gradients. Thermography was used to determine thermal gradients preceding the burn front, during the reaction of the consolidated heat powder. The techniques involved along with the resulting thermography will be discussed.

Kelly, M.D.; Abney, L.D.

1984-01-01

188

Mechanical milling of magnesium powder  

Microsoft Academic Search

The evolution of microstructure during mechanical milling of magnesium powder has been studied. Commercially pure (99.6%, ?325 mesh) magnesium powder was mechanically milled in a modified SPEX 8000 shaker mill in an inert atmosphere. The optical microscopy of the powder in the early stage of milling showed deformation by twinning and re-twinning within the grains developing sub-grain boundaries, which eventually

S Hwang; C Nishimura; P. G McCormick

2001-01-01

189

Microstructural evaluation of as-solidified and heat treated. gamma. -TiAl based powders  

SciTech Connect

Powders with nominal compositions (in atomic %) Ti-48Al and Ti-48Al-2Nb-2Cr were prepared by the plasma rotating electrode process (PREP) and gas atomization (GA) techniques. As-solidified and heat treated (1000{degrees} C/3 hr) powder samples were examined by metallography, SEM, X-ray diffraction, and TEM. The microstructures of the powders were characterized as a function of atomization technique, alloy content, powder particle size (solidification rate), and thermal history. All of the as-solidified powders were comprised of disordered {alpha}, and ordered {alpha}{sub 2}-Ti{sub 3}Al and {gamma}-TiAl. For both alloys, a larger volume fraction of {alpha} and {alpha}{sub 2} was observed in the PREP powders relative to GA powders of comparable size. Additionally, for both alloys and both atomization techniques, the volume fraction of {alpha}{sub 2} was observed to increase with decreasing powder particle size. In general, the PREP powders appeared to solidify more rapidly than the GA powders. Possible reasons for the differences in microstructures and solidification rates observed for the two atomization techniques will be discussed. Upon heat treatment, the microstructure of the powders was similar. The heat treated powders were comprised predominently of equiaxed {gamma} grains with limited amounts of lamellar {alpha}{sub 2}/{gamma} grains also present. The GA powders did exhibit a slightly higher volume fraction of {alpha}{sub 2} than the PREP powders, possibly due to slight differences in the Al content of the alloys or the higher oxygen content of the GA alloys.

Fuchs, G.E.; Hayden, S.Z.

1991-10-01

190

Plasmasynthesized nano-aluminum powders  

Microsoft Academic Search

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

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

2006-01-01

191

Thermally induced phase transformation of pearl powder.  

PubMed

The polymorphic phase transformation of thermally treated pearl powder was investigated by X-ray diffraction and thermoanalytical techniques. The phase transformation was based on quantification of the calcite content at various temperatures using Rietveld refinement analysis. The results show that the phase transformation of pearl aragonite occurred within a temperature range of 360-410 °C, which is 50-100 °C lower than the range for non-biomineralized aragonite. These thermoanalytical results suggest that the phase transformation of pearl aragonite may occur immediately after the thermal decomposition of the organic matrix in the pearl powder. An important finding is that decomposition of the organic matrix may greatly facilitate such transformation by releasing additional space for an easier structural reconstruction during the phase transformation process. PMID:23498231

Zhang, Guoqing; Guo, Yili; Ao, Ju; Yang, Jing; Lv, Guanglie; Shih, Kaimin

2013-05-01

192

Investigations of Light Transfer in Powder Bed  

Microsoft Academic Search

At selective laser sintering \\/ melting of powder bodies by laser irradiation it is very important to determine the actual energy deposited in a layer of powder and its distribution over the thickness of the powder bed. By varying the thickness of the powder bed the distribution of absorbed energy over the thickness of the powder bed has been determined.

Chivel Yuri

2011-01-01

193

Powder Dyeing Method for Cosmetics.  

National Technical Information Service (NTIS)

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

S. Iwao

1974-01-01

194

Ignition characteristics of plutonium powder.  

National Technical Information Service (NTIS)

Two fires occurred recently in a vacuum cleaner used to pick up plutonium powder during brushing of plutonium. The plutonium powder was collected by a conventional canister vacuum cleaner passing directly into the clean bag which was changed daily and sen...

L. E. Musgrave

1971-01-01

195

Electrical conductivity of carbonaceous powders  

Microsoft Academic Search

The present paper deals with the electrical conductivity of a number of carbonaceous powders undergoing a low compaction. It is shown that the contributions to the conductivity of such samples are too numerous and too complex to be solved exactly. Hence, several criteria are proposed in order to quantify the behaviour of moderately compressed powders, and thus derive several useful

A. Celzard; J. F. Marêché; F. Payot; G. Furdin

2002-01-01

196

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

197

Mound powder loader, Mod 1  

SciTech Connect

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

Gress, A.V. Jr.

1985-08-21

198

An investigation on the capability of equal channel angular pressing for consolidation of aluminum and aluminum composite powder  

Microsoft Academic Search

In this study equal channel angular pressing (ECAP) was used as a technique for consolidation of attritioned aluminum powder (45?m) with varying concentration of nano alumina powders (35nm) in tube at 200°C. The effect of ECAP on consolidation behavior of composite powder and mechanical properties of subsequent compacts are presented. It is found that ECAP has the capability of consolidating

R. Derakhshandeh. H; A. Jenabali Jahromi

2011-01-01

199

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

SciTech Connect

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

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

1994-02-01

200

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

201

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

202

Water adsorption kinetics and contact angles of pharmaceutical powders.  

PubMed

Water sorption kinetics and water contact angles have been characterized for a range of pharmaceutical powders: ambroxol hydrochloride, griseofulvin, N,n-octyl-D-gluconamide, paracetamol, sulfathiazole, and theophylline. The uptake of water by powder samples at saturated vapor pressure was modeled using a pseudo first-order kinetic relationship. Parameters from this model have been correlated with the concentration and reactivity of the active surface sites of the pharmaceutical powders and their contact angles. The study has shown that analysis of water adsorption kinetics can be a powerful technique for characterizing the surface chemistry and wettability of pharmaceutical powders, and is particularly sensitive to their surface modification through excipient adsorption: ethyl(hydroxyethyl)cellulose treatment of griseofulvin and butyryl chloride treatment of sulfathiazole are reported as case studies. PMID:15736196

Muster, Tim H; Prestidge, Clive A

2005-04-01

203

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

204

21 CFR 520.441 - Chlortetracycline powder.  

Code of Federal Regulations, 2013 CFR

... false Chlortetracycline powder. 520.441 Section 520...441 Chlortetracycline powder. (a) Specifications. Chlortetracycline powder contains not less than...administer this product with milk or milk replacers;...

2013-04-01

205

21 CFR 73.1646 - Bronze powder.  

Code of Federal Regulations, 2010 CFR

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

2009-04-01

206

21 CFR 73.1646 - Bronze powder.  

Code of Federal Regulations, 2010 CFR

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

2010-04-01

207

21 CFR 73.2647 - Copper powder.  

Code of Federal Regulations, 2010 CFR

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

2010-04-01

208

21 CFR 73.2647 - Copper powder.  

Code of Federal Regulations, 2010 CFR

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

2009-04-01

209

21 CFR 73.2645 - Aluminum powder.  

Code of Federal Regulations, 2013 CFR

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

2013-04-01

210

21 CFR 73.2646 - Bronze powder.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 2013-04-01 false Bronze powder. 73.2646 Section 73.2646 ...CERTIFICATION Cosmetics § 73.2646 Bronze powder. (a) Identity and specifications. The color additive bronze powder shall conform in identity and...

2013-04-01

211

21 CFR 73.2647 - Copper powder.  

Code of Federal Regulations, 2013 CFR

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

2013-04-01

212

Microfiltration membranes prepared from acryl amide grafted poly(vinylidene fluoride) powder and their pH sensitive behaviour  

Microsoft Academic Search

Acryl amide (AAm) was grafted onto poly(vinylidene fluoride) (PVDF) powder by a pre-irradiation induced graft polymerization technique. The chemical structure of AAm grafted PVDF powder (denoted as PVDF-g-PAM powder) was characterized by FT-IR spectroscopy and X-ray photoelectron spectroscopy (XPS) analysis. Then, the microfiltration (MF) membranes were cast from PVDF-g-PAM powder with different degrees of grafting (DG) using a phase inversion

Xuanxuan Yang; Bo Deng; Zhongying Liu; Liuqing Shi; Xiaokai Bian; Ming Yu; Linfan Li; Jingye Li; Xiaofeng Lu

2010-01-01

213

Production of reactive single- and multi-component ceramic oxide powders and fabrication of high-strength ceramics  

Microsoft Academic Search

Yttria-partially stabilized zirconia (Y-PSZ), alumina, mullite, Y-PSZ-Al2O3, alumina-zirconia and mullite-zirconia precursor powders were prepared by the hydroxide precipitation technique. The experimental conditions during precipitation were manipulated to produce homogeneous and reactive powders and examples of such variations are discussed. The formation of chemically bonded hard agglomerates was suppressed by dispersing the powders in isopropanol. The powders could be sintered to

S. Rajendran

1992-01-01

214

Properties of an atomized iron powder  

Microsoft Academic Search

ction Association by atomization of molten EP-612 steel with water under a pressure of 40 atm gauge [2] and two reduced iron powders - Brovary Powder Metallurgy Factory PZh4M2 powder and Hoeganaes NC 100.24 powder, in addition, a similar study was made of specially prepared atomized powders having particle-size distributions corresponding to those of PZh4M2 and NC 100.24 powders. By

A. E. Kushchevskii; A. T. Pekarik; O. S. Nichiporenko; A. B. Medvedovskii

1978-01-01

215

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

216

Preparation of superconductor precursor powders  

DOEpatents

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

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

1995-01-01

217

Silica powders for powder evacuated thermal insulating panel and method  

DOEpatents

A powder evacuated thermal insulating panel using generally spherical and porous silica particles of a median size less than about 100 nanometers in diameter, a pour packing density of about 0.4 to 0.6 g/cm{sup 3} and an external surface area in the range of about 90 to 600 m{sup 2}/g is described. The silica powders are prepared by reacting a tetraalkyl silicate with ammonia and water in an alcohol solvent, distilling the solution after the reaction to remove the ammonia and recover the alcohol. The resulting aqueous slurry was dried, ball-milled, and dried again to provide the silica particles with defined internal and external porosity. The nanometer size and the large external surface area of the silica particles along with the internal and external porosity of the silica particles provide powder evacuated thermal insulating panels with significantly higher R-values than obtainable using previously known silica powders. 2 figs.

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

1996-01-02

218

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

219

Method for molding ceramic powders  

DOEpatents

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

Janney, Mark A. (Knoxville, TN)

1990-01-01

220

Method for molding ceramic powders  

DOEpatents

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

Janney, M.A.

1990-01-16

221

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

222

An improved detector for powder diffractometers  

NASA Astrophysics Data System (ADS)

We present a new pixel design for powder diffractometers located at pulsed neutron sources. Small crystals of lithium gadolinium borate scintillator are enclosed in a tubular housing, with a single co-axial wave-length-shifting fiber used to collect and transmit the scintillator light to a pair of photomultiplier tubes. In the best case, 44 photoelectrons are detected from a neutron capture in 6Li event, when the light from both ends of the fiber is summed. Two techniques for discriminating against gamma background are described and quantified.

Czirr, J. Bart; McKnight, Thomas K.

2004-08-01

223

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

224

Effect of SiO 2 Powder on Mirror Polishing of InP Wafers  

Microsoft Academic Search

This paper describes a mechanical-chemical polishing technique of InP wafers using NaOCl, citric acid, and SiO2 powder solutions. The polishing rate rapidly increases by adding SiO2 powder to NaOCl and citric acid solutions. We study the dependence of the polishing rate on SiO2 powder and discuss the mechanicalchemical effect of the mirror polishing of InP wafers with NaOCl, citric acid,

Yuji Morisawa; Isao Kikuma; Naoki Takayama; Manabu Takeuchi

1997-01-01

225

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

Microsoft Academic Search

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

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

1992-01-01

226

High-temperature metallographic investigation of the sintering of reduced copper powders  

Microsoft Academic Search

1.Using the technique of high-temperature metallography, a study was made of the sintering behavior of reduced copper powders. It was established that the temperature range corresponding to the formation and growth of metallic contacts between powder particles depends on the reduction temperature of the powder.2.On the basis of experimental data on contact growth, a quantitative evaluation is made of the

G. I. Aksenov; A. N. Logvinov; I. A. Drozdov

1970-01-01

227

Determination of the temperature of a conducting powder in the detonation deposition of coatings  

Microsoft Academic Search

1.Methods have been developed for measuring the mean particle temperature and the heat content of unit mass of powder in detonation deposition.2.A technique is described for determining the proportion of powder particles undergoing partial melting as a result of contact with detonation products.3.A quantitative assessment is made of the effect of explosive mixture composition and nickel powder charging depth on

V. S. Klimenko; V. G. Skadin; S. Yu. Sharivker; E. A. Astakhov; A. I. Zverev

1978-01-01

228

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

229

Characterization of nanometer tungsten powders  

Microsoft Academic Search

Three types of tungsten powders were prepared by hydrogen reduction of three precursor powders at low temperature, which were used as samples, and were then characterized by Brunauer-Emmer-Teller (BET) method, scanning electron microscopy (SEM), transmission electronic microscopy (TEM), small angle X-ray scattering (SAXS), and field-emission scanning electron microscopy (FESEM) respectively. The results showed that although BET and SEM could not

Huiqian LI; Tao LIN; Huiping SHAO; Chengyi WU; Zhimeng GUO; Ji LUO

2008-01-01

230

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

231

Preparation of zirconium boride powder  

Microsoft Academic Search

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

Hong Zhao; Yu He; Zongzhe Jin

1995-01-01

232

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

233

Method for Production of Powders  

NASA Technical Reports Server (NTRS)

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

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

1997-01-01

234

Powder metal technologies and applications  

Microsoft Academic Search

This volume is: (1) a completely updated and expanded edition in all areas of powder production, sampling, characterization, shaping, consolidation, sintering, quality control, machining, heat treating, and P\\/M applications; (2) single source for practical engineering information on sintering practices, tool design, P\\/M metallography, dimensional control, part design, powders, binders, lubricants, and the processing, properties, and performance of P\\/M materials in

W. B. Eisen; B. L. Ferguson; R. M. German; R. Iacocca; P. W. Lee; D. Madan; K. Moyer; H. Sanderow; Y. Trudel

1998-01-01

235

Powder collection apparatus/method  

DOEpatents

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

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

1994-01-11

236

Permanent magnet microstructures using dry-pressed magnetic powders  

NASA Astrophysics Data System (ADS)

This paper presents microfabrication methods and performance analysis of bonded powder permanent magnets targeting dimensions ranging from 10 µm to greater than 1 mm. For the structural definition and pattern transfer, a doctor blade technique is used to dry press magnetic powders into pre-etched cavities in a silicon substrate. The powders are secured in the cavities by one of the three methods: capping with a polyimide layer, thermal reflow of intermixed wax-binder particles, or conformal coating with a vapor-deposited parylene-C film. A systematic study of micromagnets fabricated using these methods is conducted using three different types of magnetic powders: 50 µm Nd-Fe-B, 5 µm Nd-Fe-B and 1 µm barium ferrite powder. The isotropic magnets are shown to exhibit intrinsic coercivities (Hci) as high as 720 kA m-1, remanences (Br) up to 0.5 T and maximum energy products (BHmax) up to 30 kJ m-3, depending on the magnetic powder used. Process compatibility experiments demonstrate the potential for the magnets to withstand typical microfabrication chemical exposure and thermal cycles, thereby facilitating their integration into more complex process flows. The remanences are also characterized at elevated temperatures to determine thermal sensitivities and maximum operating temperature ranges.

Oniku, Ololade D.; Bowers, Benjamin J.; Shetye, Sheetal B.; Wang, Naigang; Arnold, David P.

2013-07-01

237

Production of Dry Powder Clots Using Piezoelectric Drop Generator  

SciTech Connect

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

Lee, Eric R

2002-09-05

238

Structural evolution in mechanically alloyed Al-Fe powders  

SciTech Connect

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

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

1995-08-01

239

Composite copper\\/stainless steel coated powders  

Microsoft Academic Search

The present research work concerns the development of new composites based on austenitic stainless steel (SS) or copper (Cu) microsized powders coated with thin nanostructured layers of copper or stainless steels, respectively. A home-manufactured magnetron sputtering system equipped with a powder vibration device was used to coat the powders. A detailed analysis of the coated copper or stainless steel powders

Mariana Matos; José M. Castanho; Maria T. Vieira

2009-01-01

240

21 CFR 73.1646 - Bronze powder.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 2013-04-01 false Bronze powder. 73.1646 Section 73.1646 Food...CERTIFICATION Drugs § 73.1646 Bronze powder. (a) Identity. (1) The color additive bronze powder is a very fine metallic powder...

2013-04-01

241

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

Microsoft Academic Search

Densifying nonmined diamond powder precursors with diamond produced by chemical vapor infiltration is an attractive approach for forming thick diamond deposits that avoids many potential manufacturability problems associated with predominantly chemical vapor deposition (CVD) processes. We have developed two techniques: electrophoretic deposition and screen printing, to form diamond powder precursors on substrates. We then densify these precursors in a hot

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

1994-01-01

242

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

243

The high-resolution powder diffractometer at the high flux isotope reactor  

Microsoft Academic Search

Neutron powder diffraction is increasingly recognized as one of the most powerful techniques for studying the structural and magnetic properties of advanced materials. Despite the growing demand to study an ever-increasing array of interesting materials, there is only a handful of neutron diffractometers available to serve the US neutron scattering community. This article describes the new high-resolution powder diffractometer that

V. O. Garlea; B. C. Chakoumakos; S. A. Moore; G. B. Taylor; T. Chae; R. G. Maples; R. A. Riedel; G. W. Lynn; D. L. Selby

2010-01-01

244

Direct determination of 25 elements in dry powdered plant materials by X-ray fluorescence spectrometry  

Microsoft Academic Search

An X-ray fluorescence spectrometric (XRF) method has been developed for the direct determination of Na, Mg, Al, Si, P, S, K, Cl, Ca, Ti, Mn, Fe, Cu, Ni, Zn, Pb, Rb, Sr, Mo, Ba, Br, V, Cr, Co and As in plant samples using the pressed powder pellet technique, which uses 1 g of the dry powdered material. Correction for

Guohui Li; Shouzhong Fan

1995-01-01

245

Effect of infrared heating on quality and microbial decontamination in paprika powder  

Microsoft Academic Search

Infrared radiation (IR) was explored as a technique for decontaminating paprika powder. The effect of water activity (aw) and IR heat flux on paprika temperature and water loss were measured during near- or medium-IR heating. Paprika was evaluated in terms of colour, aw, natural flora, and inoculated Bacillus cereus spores. Surface temperatures were considerably higher than temperatures inside the powder,

N. Staack; L. Ahrnea; E. Borch; D. Knorr

2008-01-01

246

Numerical simulation of metallic powder flow in a coaxial nozzle for the laser aided deposition process  

Microsoft Academic Search

Laser aided deposition process offers the ability to make a metal component directly from CAD drawings. Analysis of metallic powder flow in the feeding system is of particular significance to researchers in order to optimize this technique. Powder flow simulation holds a critical role in understanding flow phenomenon so as to ensure proper design and sound functionality of the coaxial

Heng Pan; Frank Liou

2005-01-01

247

Optimization of milling time before and after recalcination on HTR processed strontium hexaferrite powder  

Microsoft Academic Search

HTR (Hydrogen Treatment and Recalculation) process is a novel technique for heat treatment of conventional strontium hexaferrite powder in static hydrogen and then its recalcination in air. This process has a marked effect on the microstructure and on the magnetic properties of the material. In this work, this HTR-processed powder has been milled before and after recalcination, and the effect

S. A. Seyyed Ebrahimi

2006-01-01

248

Contact thermal conductivity of a powder bed in selective laser sintering  

Microsoft Academic Search

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

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

2003-01-01

249

Dry particle coating for improving the flowability of cohesive powders  

Microsoft Academic Search

Several dry processing techniques are used to coat cohesive cornstarch powder with different size silica particles. For nanosized silica guest particles, FESEM images show that both the magnetic assisted impaction coater (MAIC) and the hybridizer (HB) produce particles that are significantly more uniformly coated than using either a V-shape blender or simple hand mixing. Image analysis confirms that MAIC and

Jun Yang; Ales Sliva; Amit Banerjee; Rajesh N. Dave; Robert Pfeffer

2005-01-01

250

Shock consolidation of rapidly solidified type 304 stainless steel powders  

Microsoft Academic Search

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

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

2008-01-01

251

Optimisation of powders for pulmonary delivery using supercritical fluid technology  

Microsoft Academic Search

Supercritical fluid technology exploited in this work afforded single-step production of respirable particles of terbutaline sulphate (TBS). Different crystal forms of TBS were produced consistently, including two polymorphs, a stoichiometric monohydrate and amorphous material as well as particles with different degrees of crystallinity, size, and morphology. Different solid-state and surface characterisation techniques were applied in conjunction with measurements of powder

Mahboob Rehman; Boris Y Shekunov; Peter York; David Lechuga-Ballesteros; Danforth P Miller; Trixie Tan; Paul Colthorpe

2004-01-01

252

Adsorption of basic dyes from aqueous solution onto pumice powder  

Microsoft Academic Search

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

Feryal Akbal

2005-01-01

253

FTIR study of ultradispersed diamond powder synthesized by explosive detonation  

Microsoft Academic Search

Ultradispersed diamond (UDD) powders synthesized by explosive detonation were studied by FTIR to explore their surface functional groups. Deconvolution and second derivative spectra and curve fitting techniques were used to ascertain the frequencies of functional groups. Samples after oxidation by two kinds of mixed acid and after reduction in hydrogen were investigated. Experimental results indicated that several types of carbonyl

T. Jiang; K. Xu

1995-01-01

254

Metallography of Fe\\/KC10â powders  

Microsoft Academic Search

Fe and KC10â powders are blended together and pressed to form heat pellets. Pellet uniformity is required to ensure consistent and continuous reaction and is necessary to conduct physical measurements such as thermal conductivity and thermal diffusivity. Uniformity of density and composition was determined by metallographic and image analysis. The techniques of sample preparation and sectioning the parts while retaining

M. D. Kelly; C. S. Gustin; K. Varga

1984-01-01

255

SIEVE CASCADOGRAPHY FOR CHARACTERIZING PARTICLE SHAPE MIXES OF POWDERS  

Microsoft Academic Search

Particle shape has a profound influence on the behavior of the particles present in powders, controlling the manner in which they react, segregate, flow, and agglomerate. The currently available technique of Fourier transformation to characterize particle shape is cumbersome and can be used only by a skilled operator. Recently developed, the Sieve Cascadograph is able to characterize the shape of

THOMAS P. MELOY; NIGEL CLARK; T. E. DURNEY; B. PITCHUMANI

1984-01-01

256

Quality and authenticity of commercial aloe vera gel powders  

Microsoft Academic Search

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

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

2007-01-01

257

Synchrotron powder diffraction on Aztec blue pigments  

NASA Astrophysics Data System (ADS)

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

Sánchez Del Río, M.; Gutiérrez-León, A.; Castro, G. R.; Rubio-Zuazo, J.; Solís, C.; Sánchez-Hernández, R.; Robles-Camacho, J.; Rojas-Gaytán, J.

2008-01-01

258

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

259

Production and consumption of aluminum powders (review)  

Microsoft Academic Search

UDC 621.762 The prod, ration of powder products of aluminum and its alloys (medium and very fine powders, pastes, granules) is one of the fastest growing areas of international aluminum metallurgy. In terms of volume of production, the output of aluminum powders and pastes is second after iron powders. World pro~iuction of powder aluminum products annually during the period 1993-1996

O. S. Nichiporenko

1997-01-01

260

Assessing flowability of small quantities of cohesive powder using distinct element modelling  

NASA Astrophysics Data System (ADS)

The characterisation of cohesive powder flowability is often required for reliable design and consistent operation of powder processes. This is commonly achieved by mechanical testing techniques on bulk powder, such as shear test, but these techniques require a relatively large amount of powder and are carried out at large pre-consolidation loads. Many industrial cases require small amounts of powders to be handled and processed, such as filling and dosing of capsules. In other cases, the availability of testing powders could be a limiting issue. It has been shown that under certain circumstances, indentation on a cohesive powder bed by a blunt indenter can give a measure of the resistance to powder flow (Hassanpour and Ghadiri 2007). In the present work, the ball indentation process is analysed by numerical simulations using DEM in order to investigate the operation window of the process in terms of indenter size and penetration depth. The flow resistance of the assembly, commonly termed hardness, is evaluated for a range of sample quantities and operation variables. A sensitivity analysis of bed height reveals that a minimum bed height of 20 particle diameters is required in order to achieve reliable measurements of hardness. It is also found that indenter sizes with diameters smaller than 16 particle diameters exhibit fluctuations in powder flow stress measurements. As the indenter size decreases, it moves closer to the size of bed particles. Therefore, rearrangements at the single particle level influence the force on the indenter, resulting in fluctuations, and possible compaction.

Pasha, Massih; Hare, Colin; Hassanpour, Ali; Ghadiri, Mojtaba

2013-06-01

261

Powder metal technologies and applications  

SciTech Connect

This volume is: (1) a completely updated and expanded edition in all areas of powder production, sampling, characterization, shaping, consolidation, sintering, quality control, machining, heat treating, and P/M applications; (2) single source for practical engineering information on sintering practices, tool design, P/M metallography, dimensional control, part design, powders, binders, lubricants, and the processing, properties, and performance of P/M materials in different production technologies and applications; (3) comprehensive coverage of P/M technologies and applications including warm compaction, injection molding, rapid prototyping, thermal spray forming, reactive sintering, and P/M gears, bearings, high-performance parts, composites, machine parts, electric contacts, magnetic materials, metallic foams, hardfacing powders, automotive parts, and more.

Eisen, W.B.; Ferguson, B.L.; German, R.M.; Iacocca, R.; Lee, P.W.; Madan, D.; Moyer, K.; Sanderow, H.; Trudel, Y. [eds.

1998-12-31

262

Production of Fine Metallic Powders by Hybrid Atomization Process  

NASA Astrophysics Data System (ADS)

Hybrid Atomization is a recently developed powder-making process that combines effectively free-fall gas atomization and centrifugal atomization. This technique can produce very fine spherical powders with mean diameters of around 10 micrometers, and in high yields. The present report discusses the concept and basic principles of hybrid atomization. Process experiments were carried out and the optimal processing conditions were obtained. The results show that the influences of processing parameters and optimum conditions differ greatly between the proposed and the conventional atomization processes. A new correlation of atomization equation applicable to hybrid atomization is proposed and discussed.

Minagawa, Kazumi; Liu, Yunzhong; Kakisawa, Hideki; Halada, Kohmei

263

Oxide-dispersion strengthening of porous powder metalurgy parts  

DOEpatents

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

Judkins, Roddie R. (Knoxville, TN)

2002-01-01

264

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

265

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

266

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

267

Method for Manufacturing Aluminum Oxynitride (A1ON) Powder and Other Nitrogen-Containing Powders.  

National Technical Information Service (NTIS)

A method of preparing substantially homogeneous aluminum oxynitride powder and other nitrogen-containing powders is provided. Particularly with respect to the AlON powder, the method comprises the steps of milling a mixture of aluminum and aluminum oxide ...

W. Miao

2002-01-01

268

Effects of red pepper powder on microbial communities and metabolites during kimchi fermentation.  

PubMed

To investigate the effects of red pepper powder on kimchi fermentation, Baechu (Chinese cabbage) and Mu (radish) kimchi, with and without red pepper powder, were prepared and their characteristics, including pH, colony-forming units (CFU), microbial communities, and metabolites, were periodically monitored for 40days. Measurements of pH and CFU showed that the lag phases of kimchi fermentation were clearly extended by the addition of red pepper powder. Microbial community analysis using a barcoded pyrosequencing analysis showed that the bacterial diversities in kimchi with red pepper powder decreased more slowly than kimchi without red pepper powder as kimchi fermentation progressed. The kimchi microbial communities were represented mainly by the genera Leuconostoc and Lactobacillus in all kimchi, and the abundance of Weissella was negligible in kimchi without red pepper powder. However, interestingly, kimchi with red pepper powder contained much higher proportions of Weissella than kimchi without red pepper powder, while the proportions of Leuconostoc and Lactobacillus were evidently lower in kimchi with red pepper powder compared to kimchi without red pepper powder. Metabolite analysis using a (1)H NMR technique also showed that the fermentation of kimchi with red pepper powder progressed a little more slowly than that of kimchi without red pepper powder. Principle component analysis using microbial communities and metabolites supported the finding that the addition of red pepper powder into kimchi resulted in the slowing of the kimchi fermentation process, especially during the early fermentation period and influenced the microbial succession and metabolite production during the kimchi fermentation processes. PMID:23290232

Jeong, Sang Hyeon; Lee, Hyo Jung; Jung, Ji Young; Lee, Se Hee; Seo, Hye-Young; Park, Wan-Soo; Jeon, Che Ok

2013-01-01

269

The use of elemental powder mixes in laser-based additive manufacturing  

NASA Astrophysics Data System (ADS)

This study examines the use and functionality of laser depositing alloys from mixes of elemental metallic powders. Through the use of laser-based additive manufacturing (LAM), near net-shaped 3-Dimensional metallic parts can be produced in a layer-by-layer fashion. It is customary for pre-alloyed powders to be used in this process. However, mixes of elemental powders can be used to produce alloys that are formed during the deposition process. This alternative technique requires that the elemental powders adequately mix during deposition for a homogeneous deposit to be produced. Cost savings and versatility are among several of the advantages to using elemental powder mixes in LAM. Representative alloys of 316 and 430 Stainless Steel (SS) and Ti-6Al-4V were produced with elemental powder mixes during this research. These deposits were then compared to deposits of the same material manufactured with pre-alloyed powder. Comparison between the two types of samples included; EDS analysis to examine chemical homogeneity, metallography techniques to compare microstructures, and finally hardness testing to observe mechanical properties. The enthalpy of mixing is also discussed as this can impact the resulting homogeneity of deposits produced with mixes of elemental powders. Some differences were observed between the two types of deposits for 430 SS and Ti-6Al-4V. Results indicate that deposits fabricated with mixes of elemental powders can be produced to an equivalent quality of pre-alloyed powder deposits for 316 SS. This research also proposes potential alloys that could be considered for use in an elemental powder mixing technique.

Clayton, Rodney Michael

270

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

271

Zero Discharge Organic Coatings, Powder Paint - UV Curable Paint - E-Coat. Appendixes. Volume 2.  

National Technical Information Service (NTIS)

ZDOC project funded under the Advanced Research Projects Agency (ARPA) includes an effort to evaluate and develop infrared curing techniques for powder coatings. IR curing is attractive because of increased throughput as compared to conventional thermal m...

1995-01-01

272

Waterproof Anti-Explosive Powders for Coal Mines  

NASA Astrophysics Data System (ADS)

Limestone powder characterized by hydrophobic properties is used as an anti-explosive agent in coal mining industry. Unfortunately, the standard method of producing such powder by milling limestone with stearic acid is practically unprofitable in many modernized quarries and plants, and sometimes literally impossible due to the introduction of technological changes and implementation of modern mills. Then new methods of hydrophobization of limestone surfaces ought be searched. In the work two methods hydrophobization: from the stearic acid vapour phase and from silicone solutions are proposed. Lime dust from the Czatkowice Quarry of Lime was used as a raw material during investigations. It is a good agent for research because it is possible to compare the properties of samples modified in this work to the properties of anti-explosive lime powder (Polish Standard, 1994) used in mining industry in Poland. The first technique of limestone powder hydrophobization was carried out in an apparatus of own design (Vogt, 2008, 2011), and it consisted in free sedimentation of the powder layer dispersed by stearic acid vapour in powder counter current flow. The second way of modification consisted in mixing in the evaporating dish substrates: limestone powder and dope - silicone solution - Sarsil® H-15 (Vogt & Opali?ski, 2009; Vogt & Ho?ownia, 2010). Evaluation of properties so-obtained waterproof powders was carried out according to the Polish Standard, as well as using original powder determination ways, with the Powder Characteristic Tester (Index tables, Tablets & Capsules, 2005). Moreover water vapour adsorption isotherms were obtained and the thermal decomposition of powder was made. All modified samples acquired the hydrophobic character. Therefore we can state that the both proposed methods of hydrophobization of the limestone powder are useful. The parameters obtained with the use of Powder Characteristics Tester enable us to make a characterization of limestone properties not only as a water resistant material but also from the cohesion point of view. On the base of TG, DTG or DTA and EGA curves for all investigated materials was stated that the character of the thermal decomposition of modified samples is the same as this one for raw powder, what is profitable for application of hydrophobized powders as an anti-explosive agent. W górnictwie w?gla kamiennego u?ywany jest hydrofobowy py? wapienny jako substancja stosowana w systemie zabezpiecze? przeciwwybuchowych (Cybulski, 2004). Niestety, dotychczasowy sposób wy- twarzania takiego produktu polegaj?cy na wspó?mieleniu kamienia wapiennego z kwasem stearynowym staje si? praktycznie niemo?liwy do stosowania w nowoczesnych zak?adach np. kamienio?omy. Sytuacja taka jest wynikiem wprowadzania zmian technologicznych, g?ównie zwi?zanych z wymian? starych konstrukcji m?ynów na nowe urz?dzenia. Tym samym istnieje potrzeba poszukiwania nowych metod hydrofobizacji powierzchni py?ów wapiennych. W pracy omówiono dwie nowe metody hydrofobizacji py?u wapiennego: za pomoc? par kwasu stearynowego oraz roztworu silikonowego - Sarsil® H-15. Podczas bada? u?ywano surowego py?u wapiennego pochodz?cego z Kopalni Kamienia Wapiennego w Czatkowicach. Materia? ten jest dobrym materia?em do bada? gdy? istnieje mo?liwo?? porównywania w?a?ciwo?ci materia?ów hydrofobowych otrzymanych w pracy z w?a?ciwo?ciami handlowego py?u przeciwwybuchowego (Polska Norma, 1994), u?ywanego w polskich kopalniach. Pierwszy sposób hydrofobizacji py?u wapiennego, polegaj?cy na swobodnym opadaniu py?u wapiennego w oparach kwasu stearynowego przep?ywaj?cych w przeciwpr?dzie, przeprowadzono w aparacie w?asnej konstrukcji (Vogt, 2008, 2011). Aparat gwarantuje dobry kontakt modyfikatora z ziarnami py?u. Py? opadaj?c, nie napotyka ?adnych przeszkód ulega? rozproszeniu, a wprowadzony w stanie parowym kwas stearynowy mo?e swobodnie osiada? na jego powierzchni zewn?trznej oraz penetrowa? w g??b porów, blokuj?c je dla wilgoci. Drugi sposób hydrofo

Buczek, Bronis?aw; Vogt, El?bieta

2014-03-01

273

Direct laser powder deposition - 'State of the Art'  

SciTech Connect

Recent developments on Laser Cladding and Rapid Prototyping have led to Solid Freeform Fabrication (SFF) technologies that produce net shape metal components by laser fusion of metal powder alloys. These processes are known by various names such as Directed Light Fabrication (DLF{trademark}), Laser Engineered Net Shaping (LENS{trademark}), and Direct Metal Deposition (DMD{trademark}) to name a few. These types of processes can be referred to as direct laser powder deposition (DLPD). DLPD involves fusing metal alloy powders in the focal point of a laser (or lasers) that is (are) being controlled by Computer Aided Design-Computer Aided Manufacturing (CAD-CAM) technology. DLPD technology has the capability to produce fully dense components with little need for subsequent processing. Research and development of DLPD is being conducted throughout the world. The list of facilities conducting work in this area continues to grow (over 25 identified in North America alone). Selective Laser Sintering (SLS{trademark}) is another type of SFF technology based on laser fusion of powder. The SLS technology was developed as a rapid prototyping technique, whereas DLPD is an extension of the laser cladding technology. Most of the effort in SLS has been directed towards plastics and ceramics. In SLS, the powder is pre-placed by rolling out a layer for each laser pass. The computer control selects where in the layer the powder will be sintered by the laser. Sequential layers are sintered similarly forming a shape. In DLPD, powder is fed directly into a molten metal pool formed at the focal point of the laser where it is melted. As the laser moves on the material it rapidly resolidifies to form a shape. This talk elaborates on the state of these developments.

Sears, J.W.

1999-11-01

274

Industrial aspects of synchrotron X-ray powder diffraction  

NASA Astrophysics Data System (ADS)

This paper describes some of the applications of powder diffraction using synchrotron radiation with possible applications to industry. The advantages of differing synchrotron diffraction geometries, Debye-Scherrer, Analyser crystal, Hart Parrish, and Energy Dispersive, are discussed. The paper is not a comprehensive review but nevertheless considers the wider role of these powder diffraction geometries in elucidating crystal structures, highlighted examples being taken from polymers, catalyst and new drug materials, in addition to specific studies on polymer electrolyte complexes, textured materials (e.g. asbestos), pyrochlores, zeolites and cements. In the latter two cases rapid time-resolved powder diffraction is seen to be emerging as an important development in synchrotron-based techniques.

Cernik, R. J.; Barnes, P.

1995-03-01

275

A simple procedure to prepare spherical {alpha}-alumina powders  

SciTech Connect

Spherical {alpha}-alumina powders were prepared by the controlled hydrolysis of aluminum isopropoxide in a hydrolysis system consisting of octanol and acetonitrile. Diverse solvents to dissolve reactant formed diverse hydrolysis systems and affected particle shape of {alpha}-alumina powders. The precursors crystallized to {gamma}-alumina at 1000 deg. C and converted to {alpha}-alumina at 1150 deg. C without intermediate phases. The particle morphology of precursor was retained after it crystallized to {alpha}-alumina. The heating rate influenced the particle shape and the state of agglomeration during calcination process. The thermal properties of the precursors were characterized by thermal gravimetric and differential thermal analysis. X-ray diffraction technique was used to confirm the conversion of crystalline phase of alumina powders from amorphous to {alpha}-phase. Transmission electron microscopy was used to investigate the morphologies and size of the precursors and products.

Liu Hongyu [State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116012 (China); Ning Guiling [State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116012 (China)], E-mail: ninggl@dlut.edu.cn; Gan Zhihong; Lin Yuan [State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116012 (China)

2009-04-02

276

Accurate determination of X-ray energies using powder diffraction  

NASA Astrophysics Data System (ADS)

We report synchrotron energy determinations using the powder diffraction patterns of Si (640b) and LaB6 (660) standard reference powders at a number of energies between 5 and 20 keV. The fitted peak positions of all peaks recorded on image plates were used in each energy determination. Several sources of systematic error were investigated and their connection led to physically reasonable and consistent fitting parameters. The energies were determined to better than 0.025% at all energies. Our procedure shows that the use of the accurately known lattice parameters of standard materials makes it possible to determine X-ray energies without involving the full panoply of the Rietveld technique (which involves the crystal structure, crystal perfection, particle size, preferred orientation and other parameters affecting the full powder diffraction pattern).

Rae, N. A.; Chantler, C. T.; Tran, C. Q.; Barnea, Z.

2006-11-01

277

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

278

Comparison of synthesis methods, crystal structure and characterization of strontium cobaltite powders  

Microsoft Academic Search

Hexagonal perovskite-type strontium, SrCoOx, powders were synthesized via two different solution methods: polymerized complex (PC) method based on citrate process and chemical co-precipitation (CCP) method, respectively. The single-phase, microcrystalline homogeneous SrCoOx powders were synthesized successfully using the polymerized complex technique at a lower temperature (800°C) for 10h in static air, compared with chemical co-precipitation technique. The formation process, the structure

Zhang Gaoke; Liu Ying; Yang Xia; Wei Yanping; Ouyang Shixi; Liu Hangxing

2006-01-01

279

Shape memory alloys for MEMS components made by powder metallurgy processes  

Microsoft Academic Search

The paper presents some research results in the field of NiTi shape memory alloys made through powder metallurgy techniques. These techniques allow the obtaining of materials with savings of energy and time due to use of NiTi heat formation for the material synthesis. Ni-Ti, Ni-Ti-Fe and Ni-Ti-Cu alloys were performed by self propagation high temperature synthesis, starting from elemental powders.

M. Lucaci; R. L. Orban; V. Tsakiris; D. Cirstea

2008-01-01

280

Pore formation in atomized powders  

Microsoft Academic Search

Experiments have demonstrated that contamination of an alloy with argon in the manufacture of an atomized powder takes place during two stages of the production process: during contact between argon and the melt in the furnace and during atomization. Contamination during the first stage is characteristic of centrifugal atomization, and during both stages, of gas atomization. The porosity of particles

Yu. F. Ternovoi; A. G. Tsipunov; S. B. Kuratchenko; O. M. Kuimova; K. V. Kondakova

1985-01-01

281

PRODUCTION OF LITHIUM HYDRIDE POWDER  

Microsoft Academic Search

A method for the production of lithium hydride powder is described. ; Lithium carbonate was converted into the chloride. From a saturated solution of ; the chloride lithium amalgam was produced by electrolysis. The lithium amalgam ; was then converted into the hydride by heating the amalgam in a hydrogen ; atmosphere. The apparatus used for the reaction of the

J. Novotny; M. Novotna

1959-01-01

282

Shocks in porous powder media  

NASA Astrophysics Data System (ADS)

Consideration is given to a motion model for a porous powder medium, developed previously to describe the process of combustion-to-detonation transition. The model is applicable up to pressures of 1 kbar. The case of one-dimensional motion is examined, and an effective axial intergranular pressure is introduced whose dependence on porosity during compression is obtained from experimental data.

Vainshtein, P. B.

1988-12-01

283

Metallography of powder metallurgy materials  

Microsoft Academic Search

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

Alan Lawley; Thomas F. Murphy

2003-01-01

284

Experimental Equipment for Powder Processing.  

National Technical Information Service (NTIS)

To increasing the safety factor of the space vehicles, Perspirable Skin, a new designed Thermal Protection System (TPS) was proposed by bio-mimicking the process of human sweating. Powder Metallurgy (P/M) was considered to be the best candidate method to ...

P. Kwon

2009-01-01

285

Forging of Powder Metallurgy Gears.  

National Technical Information Service (NTIS)

The objective of this program was to produce a very near-net shape spur gear by isothermal forging of a powder metallurgy 4600 grade preform. Die fill and densification on test coupons were complete at a forging temperature of 1650F (900C), pressure of 10...

B. L. Ferguson D. T. Ostberg

1980-01-01

286

POWDER COATINGS: A TECHNOLOGY REVIEW  

EPA Science Inventory

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

287

Detection and characterization of smokeless powders with ion mobility spectrometry  

NASA Astrophysics Data System (ADS)

Smokeless Powders are a class of propellants that were developed in the late 19th century to replace black powder; it has been used as an explosive in shotguns, rifles, firearms and many other larger caliber weapons. These propellants can be placed into one of three different classes according to the chemical composition of their primary energetic ingredients. Advance equipment have been designed and used for the detection of explosives devices and compounds potentially energetic. In this research we are developing an analytical methodology to detect different formulation of smokeless powders: Alliant-American Select, Alliant-Bullseye, and Alliant-Red Dot using the ion mobility spectrometry (IMS) technique. We used different surfaces like computer diskettes, CD"s, book covers and plastics to study their adsorption/desorption process. Using micropipettes, we delivered solutions with different amounts of Smokeless Powders from a 1000 ppm solution and deposit it on various types of filters to make a calibration curve. Several amounts of Smokeless Powder were deposited to the different surfaces and collected with filter paper. The samples were desorbed directly from the filter to the instrument inlet port. Subsequently, the percentage of explosive recovered was calculated.

Hernandez, Neiza M.; Rosario, Santa V.; Hernandez, Samuel P.; Mina, Nairmen

2005-05-01

288

DC Plasma Technology Applied to Powder Metallurgy: an Overview  

NASA Astrophysics Data System (ADS)

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

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

2013-01-01

289

Surface free energy characterization of powders  

NASA Astrophysics Data System (ADS)

Microcalorimetric measurements and contact angle measurements were conducted to study the surface chemistry of powdered minerals. The contact angle measurements were conducted on both flat and powdered talc samples, and the results were used to determine the surface free energy components using Van Oss-Chaudhury-Good (OCG) equation. It was found that the surface hydrophobicity of talc increases with decreasing particle size. At the same time, both the Lifshitz-van der Waals (gammasLW) and the Lewis acid-base (gammas AB) components (and, hence, the total surface free energy (gammas)) decrease with decreasing particle size. Heats of immersion measurements were conducted using a flow microcalorimeter on a number of powdered talc samples. The results were then used to calculate the contact angles using a rigorous thermodynamic relation. The measured heat of immersion values in water and calculated contact angles showed that the surface hydrophobicity of talc samples increase with decreasing particle size, which agrees with the direct contact angle measurements. The microcalorimetric and direct contact angle measurements showed that acid-base interactions play a crucial role in the interaction between talc and liquid. Using the Van Oss-Chaudhury-Good's surface free energy components model, various talc powders were characterized in terms of their acidic and basic properties. It was found that the magnitude of the Lewis electron donor, gamma s-, and the Lewis electron acceptor, gamma s+, components of surface free energy is directly related to the particle size. The heats of adsorption of butanol on various talc samples from n-heptane solution were also determined using a flow microcalorimeter. It was found that the total surface free energy (gammas) at the basal plane surface of talc is much lower than the total surface free energy at the edge surface. Furthermore, the effects of the surface free energies of solids during separation from each other by flotation and selective flocculation were studied. First, the crude kaolin was subjected to flotation and selective flocculation experiments to remove discoloring impurities (i.e., anatase (TiO2) and iron oxides) and produce high-brightness clay with GE brightness higher than 90%. The results showed that a clay product with +90% brightness could be obtained with recoveries (or yields) higher than 80% using selective flocculation technique. (Abstract shortened by UMI.)

Yildirim, Ismail

2001-12-01

290

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

291

21 CFR 520.445 - Chlortetracycline and sulfamethazine powder.  

Code of Federal Regulations, 2013 CFR

...false Chlortetracycline and sulfamethazine powder. 520.445 Section 520.445 Food...445 Chlortetracycline and sulfamethazine powder. (a) Specifications. Each pound of soluble powder contains chlortetracycline...

2013-04-01

292

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

NASA Astrophysics Data System (ADS)

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

Shanthi, N. Theresita; Selvarajan, P.; Rose, A. S. J. Lucia

2011-10-01

293

Application of Powder Technology to Military Hardware.  

National Technical Information Service (NTIS)

A short description of powder metallurgy and its possible application to the manufacture of military hardware is discussed. The first part deals with the experimental aspects of producing compacts from powders. The basic processes of material preparation ...

J. P. Drolet

1972-01-01

294

Titanium Sheet Production from Commercial Powder.  

National Technical Information Service (NTIS)

Powder metallurgy titanium sheet was produced from hydride dehydride (HDH) powder using a diverse industrial supply chain. Three different processing routes were developed and production protocols were established in each route to provide options for manu...

D. Harper T. R. Muth W. Chen W. H. Peter Y. Yamamoto

2013-01-01

295

Process for the Synthesis of Iron Powder.  

National Technical Information Service (NTIS)

A process for preparing iron powder suitable for use in preparing the iron-potassium perchlorate heat-powder fuel mixture used in thermal batteries, comprises preparing a homogeneous, dense iron oxide hydroxide precipitate by homogeneous precipitation fro...

1982-01-01

296

Chemical and Physical Properties of Tantalum Powder  

NASA Astrophysics Data System (ADS)

The present work is intended to produce capacitor grade Tantalum powder by sodium reduction of potassium tantalum fluoride prepared from an indigenous ore source. The powder has been characterized for its chemical and physical properties, and compared with the commercially available powders. It is found that indigenous powder has higher impurity levels which could, however, be reduced to acceptance limits. The average particle size is within the prescribed limits.

Purushotham, Y.; Balaji, T.; Kumar, Arbind; Govindaiah, R.; Sharma, M. K.; Sethi, V. C.; Prakash, T. L.

297

Review: aqueous tape casting of ceramic powders  

Microsoft Academic Search

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

D. Hotza; P. Greil

1995-01-01

298

METHOD FOR PRODUCTION OF SILVER POWDER  

Microsoft Academic Search

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

E. Pavlov; V. Ilyashevich; S. Zhuravleva

2009-01-01

299

Temperature evolution during compaction of pharmaceutical powders.  

PubMed

A numerical approach to the prediction of temperature evolution in tablet compaction is presented here. It is based on a coupled thermomechanical finite element analysis and a calibrated Drucker-Prager Cap model. This approach is capable of predicting transient temperatures during compaction, which cannot be assessed by experimental techniques due to inherent test limitations. Model predictions are validated with infrared (IR) temperature measurements of the top tablet surface after ejection and match well with experiments. The dependence of temperature fields on speed and degree of compaction are naturally captured. The estimated transient temperatures are maximum at the end of compaction at the center of the tablet and close to the die wall next to the powder/die interface. PMID:17969108

Zavaliangos, Antonios; Galen, Steve; Cunningham, John; Winstead, Denita

2008-08-01

300

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

SciTech Connect

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

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

1991-04-30

301

Effect of Powder Polydispersity on Aerosol Generation  

Microsoft Academic Search

Purpose. We investigated the effect of primary powder polydispersity on the generation of pharmaceutical powder aerosols, using mannitol and bovine serum albu- min (BSA) as the model compounds. Methods. Primary powders with different polydispersity but comparable physical and mass median aerodynamic diameter (MMAD) were obtained from spray drying. The polydispersity, i.e. the width of the particle size distribution, of the

Nora Y. K. Chew; Hak-Kim Chan

302

Reflection of Ultracold Neutrons from Powder Materials.  

National Technical Information Service (NTIS)

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

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

1987-01-01

303

Pourability enhancement of petn explosive powders  

Microsoft Academic Search

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

Marcia Dee Vannet; George L. Ball

1987-01-01

304

21 CFR 169.179 - Vanilla powder.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 2013-04-01 false Vanilla powder. 169.179 Section 169.179 Food and Drugs...Dressings and Flavorings § 169.179 Vanilla powder. (a) Vanilla powder is a mixture of ground vanilla beans or...

2013-04-01

305

21 CFR 169.179 - Vanilla powder.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false Vanilla powder. 169.179 Section 169.179 Food and Drugs...Dressings and Flavorings § 169.179 Vanilla powder. (a) Vanilla powder is a mixture of ground vanilla beans or...

2010-04-01

306

21 CFR 169.179 - Vanilla powder.  

Code of Federal Regulations, 2010 CFR

...2009-04-01 2009-04-01 false Vanilla powder. 169.179 Section 169.179 Food and Drugs...Dressings and Flavorings § 169.179 Vanilla powder. (a) Vanilla powder is a mixture of ground vanilla beans or...

2009-04-01

307

21 CFR 73.1645 - Aluminum powder.  

Code of Federal Regulations, 2013 CFR

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

2013-04-01

308

21 CFR 73.1647 - Copper powder.  

Code of Federal Regulations, 2013 CFR

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

2013-04-01

309

PARTICLE SIZE ANALYSIS OF TUNGSTEN METAL POWDER  

Microsoft Academic Search

A method of particle size analysis for sub-sieve, tungsten metal powder ; has been developed using the Andreasen pipette. Use of 1\\/4 per cent by volume ; of tungsten powder in demineralized water gives minimum agglomeration. The ; method is useful for comparing the distribution of different batches of tungsten ; powder. No correlation between results from this method and

H. J. de Bruin; R. C. Cairns

1957-01-01

310

Physical Characteristics of Fire-Extinguishing Powders.  

National Technical Information Service (NTIS)

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

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

1997-01-01

311

Effective thermal conductivity of copper powders  

Microsoft Academic Search

Effective thermal conductivity of copper powders of different particle size has been measured experimentally at room temperature and normal pressure using the transient hot strip method. A variation in the values of the effective thermal conductivity of these powders with their porosities is observed. To explain this variation a model for a two-phase system (powders) is developed. Theoretical calculations of

K. Bala; P. R. Pradhan; N. S. Saxena; M. P. Saksena

1989-01-01

312

Prefused Mold Powder and Its Manufacturing Technology,  

National Technical Information Service (NTIS)

The recent need for the continuous casting of steel at higher speed without subsequent surface conditioning urged the development of a new type of mold powder that can replace the conventional blended powders. The prefused powder developed to meet the nee...

T. Kishi T. Nakano T. Maruyamano H. Taniguchi M. Fuji

1987-01-01

313

Theory and Practice of Rolling Metal Powders  

Microsoft Academic Search

The theoretical and technological fundamentals are considered for rolling metal powders. The equipment and production schemes for rolling powders is described as well as unit for feeding powder between rolls for the case of manufacturing two-layer strips. The main technological schemes for production copper rollings are presented.

Gleb A. Vinogradov

2002-01-01

314

High-speed rolling of metal powders  

Microsoft Academic Search

1.A study was made of the rolling of metal powders at velocities of up to 3.2 m\\/sec with forced powder feed into the deformation zone.2.Empirical relationships were obtained enabling the mill output rate and strip thickness and density to be evaluated in terms of roll gap, rolling velocity, and powder head.

A. M. Musikhin; G. A. Vinogradov

1970-01-01

315

A comparison between superfine magnesium hydroxide powders and commercial dry powders on fire suppression effectiveness  

Microsoft Academic Search

The effectiveness of superfine magnesium hydroxide powders and commercial dry powder in fire suppression were compared in a laboratory-scale, immovable fire suppression apparatus. The investigation focused on their suppression effectiveness under various pressures. It likewise studied the relationship between the powders’ surface structures and their effectiveness on fire suppression. The microcosmic structure of the powders was observed by scanning electron

Kaiqian Kuang; Xin Huang; Guangxuan Liao

2008-01-01

316

Thermal Plasma Modification of Titanium Carbide Powder Numerical Analysis of Powder Behavior in Plasmas  

Microsoft Academic Search

Modeling of behavior of TiC powders in an Ar-H2 RF plasma has been performed with the numerical analysis of the plasma fields of velocity, temperature and concentration. The transferred energy to the powders decreases with an increase in the powder feed rate, and with a decrease in the pressure. These parameters have important effects on the powder modification.

T. Watanabe; A. Kanzawa; T. Ishigakiand; Y. Moriyoshi

1995-01-01

317

Influences of powder specifications and powder delivery on laser and powder particle interaction during the LRF process  

NASA Astrophysics Data System (ADS)

With deep studying on the process of laser rapid forming (LRF) the researchers gradually meet the knowledge that it is very important to understand the mechanism of interaction between the laser and the powder particles since it is the key point to realize the effective control of the LRF process. The high-speed photography has been employed to realize in situ observation on the delivery process of powdered materials for the first time. A group of parameters -- delivery parameters of powder is put forward to characterize the delivery process in quantitative by dealing with the digital images obtained. On the basis of quantitative description of the powder delivery, an analytical model is presented to study the attenuation of the laser power caused by the cloud of the power particles. Another analytical model is also presented to study the temperature rise of the particle irradiated by the laser. It can be found that the attenuation ratio is determined together by the powder specifications, the powder feeding parameters and the powder delivery parameters. With the off axial powder nozzle being employed in the paper, the diameter of the powder steam was always bigger than the diameter of laser spot, thus the laser processing parameters have no effect on the laser attenuation. The temperature rise of the particle is determined by the powder specifications and the powder delivery parameters too. Meanwhile the laser processing parameters also affects the temperature rise of the particle. With the decreasing of the particle radius, the irradiation heating effect increases remarkably.

Chen, Jing; Yang, Haiou; Lin, Xin; Huang, Weidong

2005-01-01

318

Mesoscale Simulations of Powder Compaction  

NASA Astrophysics Data System (ADS)

Mesoscale 3D simulations of shock compaction of metal and ceramic powders have been performed with an Eulerian hydrocode GEODYN. The approach was validated by simulating a well-characterized shock compaction experiment of a porous ductile metal. Simulation results using the Steinberg material model and handbook values for solid 2024 aluminum showed good agreement with experimental compaction curves and wave profiles. Brittle ceramic materials are not as well studied as metals, so a simple material model for solid ceramic (tungsten carbide) has been calibrated to match experimental compaction curves. Direct simulations of gas gun experiments with ceramic powders have been performed and showed good agreement with experimental data. The numerical shock wave profile has same character and thickness as that measured experimentally using VISAR. The numerical results show reshock states above the single-shock Hugoniot line as observed in experiments. We found that for good quantitative agreement with experiments 3D simulations are essential.

Lomov, Ilya.; Fujino, Don; Antoun, Tarabay; Liu, Benjamin

2009-12-01

319

MESOSCALE SIMULATIONS OF POWDER COMPACTION  

SciTech Connect

Mesoscale 3D simulations of shock compaction of metal and ceramic powders have been performed with an Eulerian hydrocode GEODYN. The approach was validated by simulating a well-characterized shock compaction experiment of a porous ductile metal. Simulation results using the Steinberg material model and handbook values for solid 2024 aluminum showed good agreement with experimental compaction curves and wave profiles. Brittle ceramic materials are not as well studied as metals, so a simple material model for solid ceramic (tungsten carbide) has been calibrated to match experimental compaction curves. Direct simulations of gas gun experiments with ceramic powders have been performed and showed good agreement with experimental data. The numerical shock wave profile has same character and thickness as that measured experimentally using VISAR. The numerical results show reshock states above the single-shock Hugoniot line as observed in experiments. We found that for good quantitative agreement with experiments 3D simulations are essential.

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

2009-12-28

320

Pixe analysis of powdered milk  

Microsoft Academic Search

An accelerator-based elemental study, using proton-induced x-ray emission (PIXE), was performed on four full-cream and four\\u000a half-cream brands of powdered milk commonly consumed in Jordan. The elements detected in the samples are S, Cl, K, Ca, Fe,\\u000a Cu, Zn, Br, and Rb. The significance of some of these elements is discussed from the viewpoint of nutrition and also their\\u000a effect

A. B. Hallak

1983-01-01

321

Dry PMR-15 Resin Powders  

NASA Technical Reports Server (NTRS)

Shelf lives of PMR-15 polymides lengthened. Procedure involves quenching of monomer reactions by vacuum drying of PRM-15 resin solutions at 70 to 90 degree F immediately after preparation of solutions. Absence of solvent eliminates formation of higher esters and reduces formation of imides to negligible level. Provides fully-formulated dry PMR-15 resin powder readily dissolvable in solvent at room temperature immediately before use. Resins used in variety of aerospace, aeronautical, and commercial applications.

Vannucci, Raymond D.; Roberts, Gary D.

1988-01-01

322

Polycapillary optics for powder diffraction  

Microsoft Academic Search

In this paper, we describe a low power system using Polycapillary collimating and focusing optics that were designed to collect Cu Ka radiation from an Oxford Ultra-Bright micro-focus source for X-ray powder diffraction measurements. The characterizations of the source and polycapillary optics are presented. A collimator with two apertures was used to block high energy X-rays. An optic alignment system

Huapeng Huang; Carolyn A. MacDonald; Walter M. Gibson; John Chik; Adrian Parsegian; Igor Y. Ponomarev

2001-01-01

323

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

324

21 CFR 520.1628 - Oxfendazole powder and pellets.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 2013-04-01 false Oxfendazole powder and pellets. 520.1628 Section 520...ANIMAL DRUGS § 520.1628 Oxfendazole powder and pellets. (a) Specifications â(1) Powder for suspension. Each gram of powder...

2013-04-01

325

Anti-Corrosive Powder Particles  

NASA Technical Reports Server (NTRS)

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

Parker, Donald; MacDowell, Louis, III

2005-01-01

326

Mesoscale simulations of powder compaction  

NASA Astrophysics Data System (ADS)

Mesoscale 3D simulations of metal and ceramic powder compaction in shock waves have been performed with an Eulerian hydrocode GEODYN. The approach was validated by simulating shock compaction of porous well-characterized ductile metal using Steinberg material model. Results of the simulations with handbook values for parameters of solid 2024 aluminum have good agreement with experimental compaction curves and wave profiles. Brittle ceramic materials are not so well studied as metals, so material model for ceramic (tungsten carbide) has been fitted to shock compression experiments of non-porous samples and further calibrated to experimental match compaction curves. Direct simulations of gas gun experiments with ceramic powder have been performed and showed good agreement with experimental data. Numerical shock wave profile has same character and thickness as measured with VISAR. Numerical results show evidence of hard-to-explain reshock states above the single-shock Hugoniot line, which have also been observed in the experiments. We found that to receive good quantitative agreement with experiment it is essential to perform 3D simulations, since 2D results tend to underpredict stress levels for high-porosity powders regardless of material properties. We developed a process to extract macroscale information for the simulation which can be directly used in calibration of continuum model for heterogeneous media.

Lomov, Ilya; Antoun, Tarabay; Liu, Benjamin

2009-06-01

327

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

Microsoft Academic Search

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

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

2012-01-01

328

Effect of SiO2 Powder on Mirror Polishing of InP Wafers  

NASA Astrophysics Data System (ADS)

This paper describes a mechanical-chemical polishing technique of InP wafers using NaOCl, citric acid, and SiO2 powder solutions. The polishing rate rapidly increases by adding SiO2 powder to NaOCl and citric acid solutions. We study the dependence of the polishing rate on SiO2 powder and discuss the mechanicalchemical effect of the mirror polishing of InP wafers with NaOCl, citric acid, and SiO2 powder solutions. We observe an increase in the polishing rate of InP wafers from 0.2 to 0.9 µm/min when SiO2 powder is added to NaOCl and citric acid solutions.

Morisawa, Yuji; Kikuma, Isao; Takayama, Naoki; Takeuchi, Manabu

1997-12-01

329

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

NASA Astrophysics Data System (ADS)

Refractory zirconium diboride and tantalum monocarbide ceramic powders were sprayed using an electrothermal explosion caused by a high-voltage electric breakdown and large-current discharge heating. This spray technique was improved using a purpose-designed powder container, which made it possible to melt the powder completely and accelerate it to impinge on substrates. The electrical energy applied to the powder was estimated to be about twice the energy theoretically needed to melt just the powder. Although the ceramics used in this work are hard-sintered materials by nature, they could be sprayed and deposited to form coatings on metal substrates without additives and sintering agents. The coatings formed exhibited no chemical decomposition in the boride, and only small amounts of decarburization in the carbide due to its nonstoichiometry. The tantalum carbide coating mixed with iron and aluminum substrates in the range of 10 ?m to several tens of micrometers.

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

1997-12-01

330

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

NASA Astrophysics Data System (ADS)

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

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

2013-06-01

331

Cu 3P as anode material for lithium ion battery: powder morphology and electrochemical performances  

NASA Astrophysics Data System (ADS)

Cu 3P is studied as a potential material to be used as anode in a Li-ion battery. Depending on the synthetic route, solvothermal, ball-milling (with or without annealing), spray method or ceramic, used for its preparation, Cu 3P shows various particle sizes and crystallinities. The electrochemical reactivity towards lithium of these various Cu 3P powders is discussed through galvanostatic and potentiodynamic measurements, electron microscopy techniques, and X-ray diffraction on powder. Electrochemical performances, especially initial capacity and capacity retention, are shown to strongly correlate to the powder morphologies: small particle size favors high capacity values and the operation scan rate affects the capacity depending on the degree of crystallinity of the powder. On other hand, the battery capacity retention is better with microsized powders.

Bichat, Marie-Pierre; Politova, Tatiana; Pfeiffer, Heriberto; Tancret, Franck; Monconduit, Laure; Pascal, Jean-Louis; Brousse, Thierry; Favier, Frédéric

332

Modelling and simulation of powder-snow avalanches  

NASA Astrophysics Data System (ADS)

Finite volume release gravity currents of large density contrast on steep slopes, representing powder-snow avalanches, are simulated numerically using a dynamic mesh adaptation technique. This technique allows to treat large Reynolds numbers and large density contrast flows, but it is (presently) restricted to two dimensions. Comparison of numerical results with experiments in the Boussinesq limit shows that 2D simulations capture the essential flow dynamics. The physics of powder-snow avalanches is analysed on hand of the similarity model developed by Rastello and Hopfinger (2004) and briefly reproduced here. The numerical simulations provide the closure parameters required in this model and give access to the flow structure. The non-Boussinesq effect is to decrease substantially the spatial growth in height and to increase the aspect ratio, hence the overall flow structure. To cite this article: J. Étienne et al., C. R. Mecanique 334 (2006).

Étienne, Jocelyn; Rastello, Marie; Hopfinger, Emil J.

2006-08-01

333

Titanium alloy powder preparation for selective laser sintering  

Microsoft Academic Search

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

B. Engel; D. L. Bourell

2000-01-01

334

Synthesis and characterization of pure nanocrystalline magnesium aluminate spinel powder  

Microsoft Academic Search

Synthesis of nanocrystalline magnesium aluminate spinel (MgAl2O4) by mechanical activation of a powder mixture containing Al2O3 and MgCO3 with subsequent annealing was investigated. Simultaneous thermal analysis (STA), X-ray diffraction (XRD), and scanning electron microscopy (SEM) techniques were utilized to characterize the as-milled and annealed samples. Results showed that pure nanocrystalline spinel could be fabricated completely by 5h of mechanical activation

F. Tavangarian; R. Emadi

2010-01-01

335

Isolation of Gingerols from Powdered Root Ginger by Countercurrent Chromatography  

Microsoft Academic Search

A rapid process has been developed for the isolation of [6]-, [8]- and [10]-gingerols, in quantities between 40mg to 500mg, from powdered root ginger using countercurrent chromatography. Minor modifications to the procedure allowed the separation of [4]- gingerol. Optimisation of the CCC technique also led to the development of a normal phase HPLC system using a diol-bonded column eluted with

John E. Farthing; Melanie J. Oneill

1990-01-01

336

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

337

Thermal Conductivity of Hydride Powders Layers Interacted With Hydrogen  

Microsoft Academic Search

The results of experiments on measurements of reacting with hydrogen hydride beds thermal conductivity coefficient are presented\\u000a in the article. Installation, designs of measuring cell, and experimental technique for measurements of thermal conductivity\\u000a of various hydride layers (including various metal fillers as well) are briefly described. Experiments were carried out with\\u000a use of different hydrides, including LaNi5. Powders with particle

A. I. Solovey; Y. U. I. SHANIN

338

Photoluminescent spectroscopy measurements in nanocrystalline praseodymium doped zirconia powders  

Microsoft Academic Search

Praseodymium doped zirconia powder (ZrO2: (0.53 at%) Pr3+) was prepared by a co-precipitation technique and annealed in air at a temperature Ta = 950 °C. The x-ray diffraction pattern shows a nanocrystalline structure composed of 29.6% monoclinic and 70.4% cubic-tetragonal phases. Medium infrared and Raman analysis confirms the monoclinic\\/cubic-tetragonal crystalline structure and proves the absence of praseodymium aggregates in the

F. Ramos-Brito; H. Murrieta S; J. Hernández A; E. Camarillo; M. García-Hipólito; R. Martínez-Martínez; O. Álvarez-Fragoso; C. Falcony

2006-01-01

339

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

340

Interparticle force based methodology for prediction of cohesive powder flow properties  

NASA Astrophysics Data System (ADS)

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

Esayanur, Madhavan Sujatha Sarma

341

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

342

An Investigation Into Mechanochemical Synthesis of Nanocrystalline Hexaferrite Powder  

NASA Astrophysics Data System (ADS)

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

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

343

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

Microsoft Academic Search

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

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

2006-01-01

344

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

Microsoft Academic Search

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

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

2007-01-01

345

Trends in powder processing equipment  

SciTech Connect

Spray drying is the most widely used process for producing particles. It is used in industries other than ceramics including food, chemicals, and pharmaceutical. The process involves the atomization of a liquid feed stock into a spray of droplets and contacting the droplets with hot air in a drying chamber. The sprays are produced by either rotary or nozzle atomizers. Evaporation of moisture from the droplets and formation of dry particles proceed under controlled temperature and airflow conditions. Powder is then discharged continuously from the drying chamber. Spray drying equipment is being improved to handle an ever-increasing number of applications. Several developments in particle-size reduction equipment are also described.

Sheppard, L.M.

1993-05-01

346

Analysis of the surface energy of pharmaceutical powders by inverse gas chromatography.  

PubMed

The behavior of pharmaceutical solids, during either processing or use, can be noticeably affected by the surface energetics of the constituent particles. Several techniques exist to measure the surface energy, for example, sessile drop, and dynamic contact angle measurements. Inverse gas chromatography (IGC) is an alternative technique where the powder surface is characterized by the retention behavior of minute quantities of well-characterized vapors that are injected into a column containing the material of interest. Recently published articles using IGC on pharmaceutical powders have ranged from linking surface energetic data with triboelectric charging to studying the effect of surface moisture on surface energetics. Molecular modelling has also recently been used to explore the links between IGC data and the structural and chemical factors that influence surface properties, thereby achieving predictive knowledge regarding powder behavior during processing. In this minireview, the reported applications of IGC in the analysis of pharmaceutical powders are summarized and the major findings highlighted. PMID:11835214

Grimsey, Ian M; Feeley, Jane C; York, Peter

2002-02-01

347

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

NASA Astrophysics Data System (ADS)

To improve the thermal stability of separators for lithium batteries, we have developed heat-resistant separator films based on ceramic powder. These ceramic powder based separators (CPS) consist of ceramic powder with binder resin. We used two different particle size powders of aluminum oxide (0.01 or 0.3 ?m). By mixing ceramic powder and resin at an appropriate content ratio, both types of CPS films satisfied needs for the heat-resistance. Furthermore, CPS film using 0.01 ?m powder showed excellent charge-discharge cycling properties when applied to lithium rechargeable batteries as a separator.

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

348

TEM investigation of nanophase aluminum powder.  

PubMed

Nanophase aluminum powder was characterized in a field-emission-gun transmission electron microscope (TEM). Different techniques were used to investigate the structure of the particles, including conventional bright-field and dark-field imaging, scanning transmission electron microscopy (STEM), high-resolution lattice imaging, diffraction studies, energy dispersive X-ray spectroscopy (EDS) analysis and mapping, and electron energy loss spectroscopy (EELS) analysis and mapping. It has been established that the particle cores consist of aluminum single crystals that sometimes contain crystal lattice defects. The core is covered by a passivating layer of aluminum oxide a few nanometers thick. The alumina is mostly amorphous, but evidences of partial crystallinity of the oxide were also found. The thickness of this layer was measured using different techniques, and the results are in good agreement with each other. The particles are agglomerated in two distinct ways. Some particles were apparently bonded together during processing before oxidation. These mostly form dumbbells covered by a joint oxide layer. Also, oxidized particles are loosely assembled into relatively large clusters. PMID:17481322

Gertsman, Valéry Y; Kwok, Queenie S M

2005-10-01

349

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

Microsoft Academic Search

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

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

2009-01-01

350

Spectral, electrical and thermal properties of electron-irradiated jL-threonine single crystals  

NASA Astrophysics Data System (ADS)

Electrons of energy 6 MeV have been irradiated on L-threonine single crystals. Crystals irradiated at various electron fluences were subjected to various techniques such as Fourier transform infrared spectroscopy, dielectric and Kurtz-Perry powder second harmonic generation analyses. Differential scanning calorimetry measurement has also been carried out to test the thermal stability of the irradiated samples. The results have been discussed in detail.

Kumar, G. Ramesh; Raj, S. Gokul; Bogle, K. A.; Dhole, S. D.; Bhoraskar, V. N.; Mohan, R.

351

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

NASA Astrophysics Data System (ADS)

L-arginine dihydrofluoride of dimensions upto 15×10×9 mm 3 was successfully grown by slow evaporation technique from aqueous solution. The crystal was characterized by X-ray diffractometry, Elemental analysis, FT-IR, UV-Vis-NIR spectroscopy, thermal and microhardness studies. The dielectric constant and dielectric loss of the crystal were studied as function of frequency. Photoconductivity studies were also carried out on the sample. Kurtz powder SHG measurement confirms the NLO property of the grown crystals.

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

2010-01-01

352

Effects of Calcination and Hot-Pressing Temperatures of Magnesium Fluoride Powder on Its Optical Property  

Microsoft Academic Search

Finely dispersed magnesium fluoride powder, synthesized by a solution technique and calcined at 480-630°C, was hot-pressed at temperatures varying within the range of 570-690°C. The effects of both the calcining temperature and hot-pressing temperature of MgF2 powders on the optical transmittance were investigated to determine the optimum combination temperatures to increase the transmittance in the short-wavelength region of the spectrum.

Chen-Shen Chang; Min-Hsiung Hon; Sheng-Jenn Yang

1990-01-01

353

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

Microsoft Academic Search

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

S Ananta

2004-01-01

354

Rapidly solidified Fe–6.5%Si alloy powders for high frequency use (abstract)  

Microsoft Academic Search

Fe–(3?6.5%) Si alloy powders having a high magnetic induction (Bs) and a low core loss value for high frequency use were obtained by an extractive melt spinning as well as a centrifugal atomization technique. Sintered core rings made by the rapidly solidified Fe–6.5% Si powders exhibited the high frequency electromagnetic properties: saturated induction (B8) of 1.23 T, coercivity (Hc) of

Seung Duk Choi; Choong Jin Yang

1996-01-01

355

Gas gun consolidation of centrifugally atomized-type 304 SS powders  

Microsoft Academic Search

The consolidation of RSP Type 304 SS powders is being addressed using shock wave techniques. Controlled tests are underway using a gas gun for the powder consolidation. Pertinent test parameters include peak pressure, shock duration, and particle size distribution. The latter involves two near mono-sized fractions of 30 {plus minus} 10μm and 75 {plus minus} 10μm, in addition to the

J. E. Flinn; Y Gupta; P Bellamy; L. H. Schoenlein

2008-01-01

356

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

Microsoft Academic Search

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

S. B. Hanna; N. M. Ghoneim

1986-01-01

357

Effect of pH on the dispersability of silicon carbide powders in aqueous media  

Microsoft Academic Search

The dispersion behaviour of commercial silicon carbide (SiC) powders of various grit sizes in deionised water was studied over the pH range 2–11. The slips were characterised for the state of their dispersion by employing the various quantitative diagnostic techniques e.g. particle size distribution, sedimentation, rheological behaviour, viscosity and zeta potential. SiC powders were found to get optimally dispersed at

R Ramachandra Rao; H. N Roopa; T. S Kannan

1999-01-01

358

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

359

The high-resolution powder diffractometer at the high flux isotope reactor  

Microsoft Academic Search

Neutron powder diffraction is increasingly recognized as one of the most powerful techniques for studying the structural and\\u000a magnetic properties of advanced materials. Despite the growing demand to study an ever-increasing array of interesting materials,\\u000a there is only a handful of neutron diffractometers available to serve the US neutron scattering community. This article describes\\u000a the new high-resolution powder diffractometer that

Vasile O Garlea; Bryan C Chakoumakos; Scott A Moore; Gerald Brent Taylor; Timothy Chae; Ron G Maples; Richard A Riedel; Gary W Lynn; Douglas L Selby

2010-01-01

360

UâOâ powder from uranyl-loaded cation exchange resin  

Microsoft Academic Search

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

1985-01-01

361

Defect structures in zirconium diboride powder prepared by self-propagating high-temperature synthesis  

Microsoft Academic Search

A comparative study on the defect structures in zirconium diboride (ZrB2) powder prepared by three different techniques namely a self-propagating high-temperature synthesis (SHS), a replacement reaction process (RRP) and a carbothermic reduction process (CRP) was carried out. It was established that the powder prepared by SHS process has more defect structures due to strongly higher rate of heating and cooling

S. K. Mishra; S. Das; L. C. Pathak

2004-01-01

362

Rapid synthesis of YAG nano-sized powders by a novel method  

Microsoft Academic Search

Nano-sized powders of aluminum yttrium garnet (YAG) have been successfully synthesized by a mixed solvo-thermal method at low temperature (300 °C) and low pressure (10 MPa). The phase transformation, composition and micro-structural features of the crystalline samples were characterized by X-ray powder diffraction, IR and TEM techniques. It was found that type of solvent, reaction temperature and time were important

Xia Li; Hong Liu; Ji-yang Wang; Hong-mei Cui; Feng Han; Xu-dong Zhang; R. I. Boughton

2004-01-01

363

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

Microsoft Academic Search

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

Aleksandra Matraszek; Ewa Radominska; Irena Szczygiel

2011-01-01

364

Grinding Si3N4 Powder In Si3N4 Equipment  

NASA Technical Reports Server (NTRS)

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

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

1989-01-01

365

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

PubMed Central

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

2012-01-01

366

Antimicrobial properties of silver-doped hydroxyapatite nano-powders and thin films  

Microsoft Academic Search

Silver-doped hydroxyapatite nanopowders were prepared using a solution based sol-gel method and thoroughly characterized using\\u000a x-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS). Antibacterial tests\\u000a showed silver-doped HAP powders prevented the growth and reproduction of bacteria. Silver-doped HAP powders were pressed into\\u000a pellets and on these pellets a pulsed laser deposition (PLD) technique was employed to

Michael Sygnatowicz; Kunttal Keyshar; Ashutosh Tiwari

2010-01-01

367

Deformation of experimentally shock-loaded quartz powders: X-ray line broadening studies  

Microsoft Academic Search

Quartz powders (mean grain size: 22 µm) were pressed into sample discs of different green densities (?0=1.65; 1.85 and 2.05 g\\/cm3) and subjected to shock pressure between 1.5 and 17.0 GPa. Peak shock pressures were determined by the impedance method using the Hugoniot curves of steel and quartz powders. Fourier techniques were used to analyse the line broadening of 5

H. Schneider; R. Vasudevan; U. Hornemann

1984-01-01

368

TiN-TiB 2 composite coatings reactively produced by electrothermally exploded powder spray  

Microsoft Academic Search

Composite coatings composed of titanium nitride, TiN, and diboride, TiB2, were reactively produced by the electrothermally exploded powder spray technique, in which feedstock powder was prepared\\u000a from titanium and boron nitride particles. The microstructure of the coating was composed of titanium-ceramic particles the\\u000a size of which were on the order of several nanometers to a few hundred nanometers. Such reactive

Hideki Tamura; Fu-Gao Wei; Takahiko Kodama

2002-01-01

369

Optimization of milling time before and after recalcination on HTR processed strontium hexaferrite powder  

Microsoft Academic Search

HTR (Hydrogen Treatment and Recalculation) process is a novel technique for heat treatment of conventional strontium hexaferrite\\u000a powder in static hydrogen and then its recalcination in air. This process has a marked effect on the microstructure and on\\u000a the magnetic properties of the material. In this work, this HTR-processed powder has been milled before and after recalcination,\\u000a and the effect

S. A. Seyyed Ebrahimi

2006-01-01

370

X-ray characterization of inert gas atomized low carbon astroloy powder  

Microsoft Academic Search

X-ray studies were carried out on an inert gas atomized low carbon (LC) astroloy powder. The as-atomized powder was sieved into different fractions of narrow size using suitable combination of sieves to study the effect of particle size on the compositional homogeneity and lattice parameter. Using a slow scanning X-ray diffraction technique, the lattice parameter of the sample and broadening

Mahendra Kumar; S. V. Nagender Naidu

2004-01-01

371

Fenoterol inhalation powder as an alternative to treatment with the metered dose inhaler.  

PubMed

Nine adult asthmatics took part in a cumulative dose response comparison of fenoterol (Berotec) inhalation powder and fenoterol metered dose inhaler. The study was carried out as a double-blind investigation using a double-dummy technique. No significant difference was observed in the lung function, in tremor or pulse rate on comparison of the two modes of administration. It is concluded that fenoterol inhalation powder is an effective and freon-free alternative to the metered dose inhaler. PMID:6581062

Dirksen, H; Groth, S

1983-01-01

372

Uranium removal from aqueous solutions by wood powder and wheat straw  

Microsoft Academic Search

The influence of initial uranium concentration, solution pH, contact time and adsorbent mass was investigated for removal\\u000a of uranium from aqueous solutions by pine wood powder and wheat straw using a batch technique. The maximum removal efficiency\\u000a of uranium achieved at pH 8 and 7 for pine wood powder and wheat straw, respectively. Langmuir and Freundlich adsorption isotherms and three

Saeed Bagherifam; Amir Lakzian; Seyed Javad Ahmadi; Mohammad Farhad Rahimi; Akram Halajnia

2010-01-01

373

Structure and thermal conductivity of powder injection molded AlN ceramic  

Microsoft Academic Search

AlN powders doped with Y2O3 (5wt.%) were compacted by employing powder injection molding (PIM) technique. The binder consisted of paraffin wax (PW, 60wt.%), polypropylene (PP, 35wt.%) and stearic acid (SA, 5wt.%). The feedstock was prepared with a solid loading of 62vol.%. The binder was removed through debinding process in two steps, solvent debinding followed by thermal debinding. At last, the

Xueli Du; Mingli Qin; Yue Sun; Zhihao Yuan; Baohe Yang; Xuanhui Qu

2010-01-01

374

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

375

Synthesis of high purity carbide powders. (Latest citations from Engineered Materials abstracts). Published Search  

SciTech Connect

The bibliography contains citations concerning the synthesis and preparation of high purity carbide powders. Articles discuss techniques of powder manufacture such as chemical vapor deposition, plasma arc reactions, sintering, hot pressing, combustion synthesis, precipitation, chemical reaction, self-propagating high temperature synthesis, shock or explosive compaction, and aerosol formation. Citations concern silicon carbides, titanium carbides, and other carbide materials and composites. (Contains 250 citations and includes a subject term index and title list.)

Not Available

1994-08-01

376

Analysis of tablet compaction. I. Characterization of mechanical behavior of powder and powder/tooling friction.  

PubMed

In this first of two articles on the modeling of tablet compaction, the experimental inputs related to the constitutive model of the powder and the powder/tooling friction are determined. The continuum-based analysis of tableting makes use of an elasto-plastic model, which incorporates the elements of yield, plastic flow potential, and hardening, to describe the mechanical behavior of microcrystalline cellulose over the range of densities experienced during tableting. Specifically, a modified Drucker-Prager/cap plasticity model, which includes material parameters such as cohesion, internal friction, and hydrostatic yield pressure that evolve with the internal state variable relative density, was applied. Linear elasticity is assumed with the elastic parameters, Young's modulus, and Poisson's ratio dependent on the relative density. The calibration techniques were developed based on a series of simple mechanical tests including diametrical compression, simple compression, and die compaction using an instrumented die. The friction behavior is measured using an instrumented die and the experimental data are analyzed using the method of differential slices. The constitutive model and frictional properties are essential experimental inputs to the finite element-based model described in the companion article. PMID:15236452

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

2004-08-01

377

Antibacterial characteristics of magnesium oxide powder  

Microsoft Academic Search

The antibacterial activity of magnesium oxide (MgO) was studied. Inhibitory zones appeared around the MgO powder slurry put directly on nutrient agar plates seeded with Escherichia coli or Staphylococcus aureus. However, no zone was observed using a penicillin cup to avoid contact between the bacteria and the MgO powder. Moreover, the supernatant solution of the MgO powder slurry and a

J. Sawai; H. Kojima; H. Igarashi; A. Hashimoto; S. Shoji; T. Sawaki; A. Hakoda; E. Kawada; T. Kokugan; M. Shimizu

2000-01-01

378

Chemical synthesis of magnesium niobate powders  

Microsoft Academic Search

Magnesium niobate (MgNb2O6) powders in orthorhombic form have been successfully prepared via an oxalate synthetic route. Solutions of magnesium chloride hexahydrate and niobium pentachloride were used as the starting materials in the synthesis of MgNb2O6 powders. The formation mechanism of MgNb2O6 was clarified by TG–DTA, FT-IR and X-ray diffraction (XRD). The morphology of the formed powders was examined by scanning

L. Srisombat; Supon Ananta; S. Phanichphant

2004-01-01

379

Process for the synthesis of iron powder  

DOEpatents

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

Welbon, W.W.

1983-11-08

380

Modeling of laser cladding with powder injection  

Microsoft Academic Search

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

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

2004-01-01

381

A method for rubber toughening powder coatings  

Microsoft Academic Search

This paper describes a new method for rubber toughening brittle powder coatings. The design involves the use of toughening agents with specific physical and chemical properties. The modifiers are low-to-medium molecular weight polymers with polymerizable end groups (macromonomers). To achieve the physical properties required for fabrication into fine powders for subsequent deposition using conventional powder coating equipment, semi-crystalline polymers with

J. L. Hedrick; R. D. Allen; A. Diaz; J. G. Hilborn; J. C. Hedrick

1993-01-01

382

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

383

Microbial Quality of Formulated Infant Milk Powders  

Microsoft Academic Search

Study was carried out to examine the microbiological quality of Infant formula milk powder. Total 60 of dried milk powders, 20 each of Group A (1-6), B (7-12) and C (13-18 months). Infant formula milk powders were purchased from Hyderabad, Sindh and evaluated for microbiological examination, like Total Viable Count (TVC), Enterobacteriaceae Count (EbC) and Yeasts and Moulds Count (YMC).

Imran Rashid Rajput; M. Khaskheli; S. Rao; S. A. Fazlani; Q. A. Shah; G. B. Khaskheli

2009-01-01

384

Dendritic microstructure in argon atomized superalloy powders  

NASA Technical Reports Server (NTRS)

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

Tewari, S. N.; Kumar, Mahundra

1986-01-01

385

Stereochemistry Determination by Powder X-ray Diffraction Analysis and NMR Spectroscopy Residual Dipolar Couplings  

SciTech Connect

A matter of technique: For a new steroidal lactol, jaborosalactol 24 (1), isolated from Jaborosa parviflora, NMR spectroscopy residual dipolar couplings and powder X-ray diffraction analysis independently gave the same stereochemistry at C23-C26. Conventional NMR spectroscopic techniques, such as NOE and {sup 3}J coupling-constant analysis failed to unambiguously determine this stereochemistry.

Garcia, M.; Pagola, S; Navarro-Vasquez, A; Phillips, D; Gayathri, C; Krakauer, H; Stephens, P; Nicotra, V; Gil, R

2009-01-01

386

Manipulation of powder characteristics by interactions at the solid–liquid interface: 1sulphadiazine  

Microsoft Academic Search

A solvent-treatment technique aiming at manipulating the properties of powdered materials is reported. Potentials of the technique were assessed using sulphadiazine (SD). A suspension of the drug in a preselected solvent (5% aqueous ammonia solution) was stirred under controlled conditions. The solvent was subsequently removed and the material dried. The effect of experimental variables such as stirring speed and time,

Y. E Hammouda; L. K El-Khordagui; I. A Darwish; A. H El-Kamel

1999-01-01

387

Superconducting properties of powder-in-tube MgB2 tapes prepared with fine powders  

Microsoft Academic Search

It is necessary to increase the Jc values to develop useful MgB2 tape. We investigated superconducting properties of in situ processed Powder-In-Tube (PIT) MgB2 tapes prepared with fine powders. Fine crystalline Mg powder with the average particle size of about 300 nm was fabricated by applying the thermal plasma method. In addition, 5?15 mol% SiC powder doping was tried to

H. Yamada; M. Hirakawa; H. Kumakura; A. Matsumoto; H. Kitaguchi

2005-01-01

388

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

Microsoft Academic Search

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

Charu V. Navaneethan; Shahrzad Missaghi; Reza Fassihi

2005-01-01

389

The Role of Powder Particle Size Distribution in the Processability of Powder Injection Molding Compounds  

Microsoft Academic Search

The role of particle size distribution of hard-metal carbide powder compounds in structural changes caused by shear deformation is investigated via their response to dynamic viscoelastic strain. Materials employed in the study are intended for the production of sintered carbide components via powder injection molding. Four grades of hard-metal carbide powders differing in their particle size distribution were mixed thoroughly

B. Hausnerova; T. Kitano; I. Kuritka; J. Prindis; L. Marcanikova

2011-01-01

390

Thermal conductivity of metal powder-polymer feedstock for powder injection moulding  

Microsoft Academic Search

Thermal conductivity of a powder injection moulding feedstock (mixture of metal powders and polymers) in solid and molten states has been measured by using the laser flash method. The filler material was 316L stainless steel powder and its content in the mixture amounted 60% by volume. An attempt has been made to employ two most promising existing mathematical models (theoretical

L. Kowalski; J. Duszczyk; L. Katgerman

1999-01-01

391

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.

392

Automated thermal conductivity probe, and applications to powders  

SciTech Connect

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

Drotning, W D

1983-01-01

393

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

NASA Astrophysics Data System (ADS)

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

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

394

Synthesis of air-sinterable lanthanum chromite powders  

SciTech Connect

Lanthanum chromites, used as current interconnections in solid oxide fuel cells (SOFCs), have high electrical conductivity and are chemically stable. However, they are difficult to fabricate under conditions compatible with other SOFC components. A novel powder synthesis technique, the glycine/nitrate process, has been developed that produces chromite powders that can be sintered to near-full density in air at 1823 K. This paper describes the glycine/nitrate process for the synthesis and fabrication of lanthanum chromites. The sintering behavior and properties of a series of glycine/nitrate-produced lanthanum chromites are discussed. Some of the materials produced by this method match the thermal expansion of the electrolyte and maintain high electrical conductivity. 16 refs., 10 figs.

Chick, L.A.; Bates, J.L.; Pederson, L.R.; Kissinger, H.E.

1989-10-01

395

Powder-metallurgical preparation of A15 superconductors  

NASA Astrophysics Data System (ADS)

The powder-metallurgical preparation of Cu-Nb3Sn microcomposite superconductors was investigated in order to economize in the manufacture of the conductors and to improve their mechanical and electrical properties. Conditions during high temperature extrusion are optimized by adding Al or Ti as reducing agents, also with a view to the following cold forming. Current densities well above 10,000 A/sq cm at 15T are obtained by applying coarse-grained Nb powder and incorporating small quantities of Ta or Ti. The current carrying behavior of the conductors was determined as a function of the degree of mechanical deformation, the cold forming technique, and the heat treatment conditions. Wires containing an internal tin source as well as bundled assemblies for high current applications were manufactured. Long wires can be produced.

Wilhelm, Manfred; Wohlleben, Karl; Springer, Engelbert; Mrowiec, Klaus; Schaper, Wilfried; Wecker, Joachim

1985-08-01

396

Target Phenomenology. Task 3 - Experimental Determination of the Infrared Spectral Optical Properties of Bulk and Powdered Aluminum Oxide.  

National Technical Information Service (NTIS)

A comparison of sample preparation, measurement techniques and optical property data for bulk and powdered aluminum oxide is made to determine the infrared complex spectral refractive index. Normal transmittance of single crystal sapphire from 1 to 9 micr...

E. R. Streed G. R. Cunnington C. K. Liu

1973-01-01

397

Development of Powder Diffraction Analysis Tools for a Nanocrystalline Specimen. An Empahsis Upon NiTi (Nitinol).  

National Technical Information Service (NTIS)

Powder diffraction is a specialized technique whose investigatory limits are constrained by the scale of the crystallized substance being scanned versus the probe beam used. When disparate in scale, with the photon spot size larger than the crystal being ...

E. Owens

2006-01-01

398

Method for producing coral powder  

US Patent & Trademark Office Database

A coral is washed with purified water or tap water, and a crushed coral is heat-treated. Proteins and other organic matter are incorporated between calcium molecules in the coral skeleton, and the organic matter is decomposed and released as volatile components. In the skeleton from which organic matter is released, a calcium skeleton having a porous structure is formed, and the surface area of pores is increased. A hydrogen gas can be retained in the structure by adsorbing a hydrogen gas to the pores in such a calcium skeleton a porous structure (micropores). The resulting coral powder, with which ions dissolved in water are easily extracted, shows a low oxidation reduction potential when dissolved in water.

2012-05-01

399

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

NASA Astrophysics Data System (ADS)

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

Baraniraj, T.; Philominathan, P.

2010-01-01

400

Oxidation sizing of iron and iron-neodymium-boron powders  

Microsoft Academic Search

A powder sizing test developed for use on WC powders has been extended for use on iron and iron-neodymium-boron powders. In this test the particle size is derived from the rate of oxidation, because finer powders oxidize quicker. The rate of oxidation is monitored in a thermogravimetric analyser, where the powders are subjected to a controlled heating rate from room

M. Stewart; B. Roebuck; M. G. Gee

1991-01-01

401

Ignition of Titanium Powder Layers by Electrostatic Discharge  

Microsoft Academic Search

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

Ervin Beloni; Edward L. Dreizin

2011-01-01

402

Electrical Resistivity of Metal Powder Aggregates  

Microsoft Academic Search

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

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

2007-01-01

403

Dynamic Powder Feeding System for Laser Cladding.  

National Technical Information Service (NTIS)

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

T. A. Jensen

1990-01-01

404

Process for Thickening and Sintering Powders.  

National Technical Information Service (NTIS)

A process is described for thickening and sintering powders of metals, metal carbides, or ceramic or similar materials, in which the powder is stirred into a metal container and heated to a high temperature within this form. At the same time the air is ev...

P. Riegelmayer

1969-01-01

405

Grinding and Characterization of Scrap Rubbers Powders  

Microsoft Academic Search

SBR and EPDM extruded profile scraps are ground under ambient conditions for further utilization in recycling and reclaiming processes. The obtained powders (SBR-r and EPDM-r, respectively) are physically, thermally, and chemically characterized and the results are analyzed as for its suitability for reuse methods. It is possible to obtain powdered SBR and EPDM rubber with irregular shape and high surface

Tatiana Weber; Aline Zanchet; Rosmary N. Brandalise; Janaina S. Crespo; Regina C. R. Nunes

2008-01-01

406

Large Bore Powder Gun Qualification (U)  

Microsoft Academic Search

A Large Bore Powder Gun (LBPG) is being designed to enable experimentalists to characterize material behavior outside the capabilities of the NNSS JASPER and LANL TA-55 PF-4 guns. The combination of these three guns will create a capability to conduct impact experiments over a wide range of pressures and shock profiles. The Large Bore Powder Gun will be fielded at

Donald A. Rabern; Robert Valdiviez

2012-01-01

407

Caking phenomena in amorphous food powders  

Microsoft Academic Search

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

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

1995-01-01

408

Constitutive mechanical modeling of BSCCO powders  

Microsoft Academic Search

In order to feed a new mechanical model of the Powder In Tube (PIT) processing BSCCO\\/Ag conductors, a plastically compressible constitutive model of the powder is proposed and its parameters measured. We use a simple compressible model of the CAM-CLAY type with work hardening and softening depending on density variation. The unknown parameters of the model, the plastic properties of

A. Allais; C. E. Bruzek; N. Lallouet; P. Montmitonnet; P. Herrmann; D. Pelissier; F. Toussaint

2003-01-01

409

Simulation and modeling of cohesive powder flow  

Microsoft Academic Search

Simulation and modeling of the flow behavior of cohesive powders are carried out through discrete element simulation (DES) and the kinetic theory of gas-based continuum model to gain a fundamental understanding of the cohesive powder flows. The cohesive forces between particles, such as van der Waal's forces, are accounted for by particle surface energy through a microscopic contact force model.

Hong Shang

1998-01-01

410

Adsorption of arsenate on untreated dolomite powder  

Microsoft Academic Search

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

G. M. Ayoub; M. Mehawej

2007-01-01

411

FBE powder and coating tests evaluated  

Microsoft Academic Search

Properties of a fusion-bonded epoxy (FBE) external pipeline coating can be significantly affected by the conditions under which the FBE powder has been stored. Nova, An Alberta Corporation, and 3M Co. undertook a program of evaluating easily run tests to determine the suitability of FBE powder. These tests are less time consuming than the most commonly used series of tests

K. E. W. Coulson; D. G. Temple; J. A. Kehr

1987-01-01

412

21 CFR 529.2464 - Ticarcillin powder.  

Code of Federal Regulations, 2013 CFR

... 6 2013-04-01 2013-04-01 false Ticarcillin powder. 529.2464 Section 529.2464 Food and Drugs FOOD...OTHER DOSAGE FORM NEW ANIMAL DRUGS § 529.2464 Ticarcillin powder. (a) Specifications. Each vial contains...

2013-04-01

413

Compatibility of header materials with pyrotechnic powder  

Microsoft Academic Search

The intent of this research program is to qualify several stainless steels, nickel-base alloys and a titanium alloy as candidates for explosive component applications. This report focuses on the compatibility of these materials with pyrotechnic powder. The powder is a combined titanium subhydride-potassium perchlorate mixture, used both wet and dry. Hollow tensile bars were utilized to discern interactions between the

Weirick

1982-01-01

414

Subharmonic Square Waves for a Vibrated Powder  

Microsoft Academic Search

We describe experiments on vibrated powders in a gas environment. Because the powders are fine, typically about 60 mum in diameter, the system is inherently two-phase in nature. In the experiments, we control the amplitude and frequency of shaking and the ambient pressure, P. At high enough accelerations, subharmonic waves appear. We focus on a novel wave form that consists

Jean-Philippe Matas; Jun Uehara; Bob Behringer

2006-01-01

415

Preparation of Silver Powder for Conductive Paste.  

National Technical Information Service (NTIS)

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

L. Y. Chai, H. Zhong, H. Wu

1994-01-01

416

Predicting the conductivity of biporous powder materials  

Microsoft Academic Search

The electrical conductivity of biporous permeable powdered materials is calculated on the basis of percolation theory. These\\u000a materials are made with a pore-forming additive having a different ratio of particle size than does the metal phase. Calculations\\u000a for nickel powder specimens as an example are in satisfactory agreement with the experimental data.

Y. N. Kruchkov; L. I. Chernyshev; L. E. Lunin

2000-01-01

417

Slip casting and nitridation of silicon powder  

NASA Astrophysics Data System (ADS)

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

Seiko, Y.

1985-03-01

418

Physical and dielectric properties of pharmaceutical powders  

Microsoft Academic Search

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

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

2003-01-01

419

Wet powder seal for gas containment  

DOEpatents

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

Stang, Louis G. (Sayville, NY) [Sayville, NY

1982-01-01

420

Effect of detergent on powder triboelectrification.  

PubMed

Triboelectrification of pharmaceutical powders during processing and manufacture may cause adhesion/cohesion effects, reduce fill and dose uniformity, affect powder flow and packing behaviour and even obstruct the manufacturing of the product. This paper presents the results of an experimental study on the triboelectrification of microcrystalline cellulose in contact with stainless steel pipes washed with several different detergents. Detergents and their concentrations were chosen to be similar to typical industrial manufacturing stages. The adhesion of powder to the surface had a considerable effect on the triboelectrification process. Therefore, polystyrene spheres were also charged in a similar way and the results were compared with the powder charging results. The results clearly indicate that detergent contamination on the pipe surface has a considerable effect on the generated charge. The detergents and powders used could be arranged in a triboelectric series with only one exception. PMID:12453608

Murtomaa, Matti; Ojanen, Kalle; Laine, Ensio; Poutanen, Jutta

2002-12-01

421

Nanostructured GGG powders via gel combustion  

NASA Astrophysics Data System (ADS)

Polycrystalline nano-sized gadolinium gallium garnet (Gd 3Ga 5O 12, GGG) powders were synthesized via a gel combustion method from a mixed solution of Ga(NO 3) 3, Gd(NO 3) 3 and citric acid. The evolution of phase composition and micro-structure of the powders were characterized by X-ray powder diffraction, thermogravimetry/differential thermal analysis and scanning electron microscopy. Well-crystallized, single phase GGG nano-sized powders could be obtained at the calcining temperature as low as 750 °C for 2 h. No any intermediate phases formed during the calcining process. The resulting powders were well dispersed and had a relatively narrow size distribution with an average particle size of approximately 30-50 nm.

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

2007-03-01

422

Substantiating powder metal life methodologies for engines  

NASA Astrophysics Data System (ADS)

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

Domas, P. A.

1993-04-01

423

Application of frequency domain photon migration to particle size analysis and monitoring of pharmaceutical powders.  

PubMed

The frequency domain photon migration (FDPM) technique was employed to determine mean particle size of pharmaceutical powders. Results show that the FDPM-measured scattering coefficient increases linearly with reciprocal mean particle size of powdered samples. In contrast to near-infrared spectroscopy techniques, FDPM technique enables determination of scattering and absorption separately so that it does not require data pretreatment and chemometric calibration models. In addition, this unique advantage provides more detailed information about powder samples, which can be used as a potential tool for on-line monitoring of not only variation of active pharmaceutical ingredient concentrations from changes in the absorption coefficient but also variation of particle sizes from changes in the scattering coefficient. PMID:12705608

Sun, Zhigang; Torrance, Sharnay; McNeil-Watson, Fraser K; Sevick-Muraca, Eva M

2003-04-01

424

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

425

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

426

A System for Concurrently Delivering a Stream of Powdered Fuel and a Stream of Powdered Oxidizer to a Combustion Chamber for a Reaction Motor.  

National Technical Information Service (NTIS)

A propellant delivery subsystem adapted to concurrently supply streams of powdered fuel and fluidized oxidizer includes one reservoir for powdered fuel and a second for powdered oxidizer. The particle size for the powdered fuel and powdered oxidizer is su...

L. M. Delionback R. M. Stein

1978-01-01

427

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

428

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

429

Synthesis and characterization of nano-sized MgB 2 powder by spray pyrolysis method  

NASA Astrophysics Data System (ADS)

The nano-sized MgB 2 powder was prepared by spray pyrolysis method in order to improve its flux pinning properties by increasing the number of grain boundaries. MgB 2 powder was synthesized using spray pyrolysis technique followed by a post-annealing process without excessive magnesium addition. The feed solution was prepared by dissolving the correct amounts of Boric acid and Magnesium acetate tetrahydrate into distillated water and ethanol solution and the overall concentration were fixed at 0.1 mol/L. During the decomposition, 96% Ar-4% H 2 was used as carrier gas. The collected powders were characterized by X-ray diffraction, scanning electron microscopy, particle size analyzer, and physical property measurement system. The particles prepared by spray pyrolysis showed spherical morphology and uniform distribution with the average size of 1 ?m. The onset of superconducting Tc for synthesized MgB 2 powder was around 38 K.

Park, S. C.; Chung, J.-K.; Lim, Y.-J.; Kang, S. G.; Song, K.-J.; Kim, C.-J.; Kim, C. J.

2008-09-01

430

21 CFR 866.1640 - Antimicrobial susceptibility test powder.  

Code of Federal Regulations, 2010 CFR

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

2009-04-01

431

21 CFR 866.1640 - Antimicrobial susceptibility test powder.  

Code of Federal Regulations, 2010 CFR

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

2010-04-01

432

21 CFR 520.445b - Chlortetracycline powder.  

Code of Federal Regulations, 2010 CFR

... false Chlortetracycline powder. 520.445b Section 520...445b Chlortetracycline powder. (a) Specifications. Chlortetracycline powder contains not less than...administer this product with milk or milk replacers;...

2009-04-01

433

21 CFR 520.445b - Chlortetracycline powder.  

Code of Federal Regulations, 2010 CFR

... false Chlortetracycline powder. 520.445b Section 520...445b Chlortetracycline powder. (a) Specifications. Chlortetracycline powder contains not less than...administer this product with milk or milk replacers;...

2010-04-01

434

21 CFR 520.2200b - Sulfachlorpyridazine powder.  

Code of Federal Regulations, 2010 CFR

...false Sulfachlorpyridazine powder. 520.2200b Section 520...2200b Sulfachlorpyridazine powder. (a) Specifications . Sodium sulfachlorpyridazine powder. (b) Sponsor . See No...lb) body weight per day in milk or milk replacer for 1 to...

2009-04-01

435

21 CFR 520.1044c - Gentamicin sulfate soluble powder.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false Gentamicin sulfate soluble powder. 520...NEW ANIMAL DRUGS § 520.1044c Gentamicin sulfate soluble powder. (a) Specifications. Each gram of gentamicin sulfate soluble powder...

2010-04-01

436

21 CFR 520.1044c - Gentamicin sulfate soluble powder.  

Code of Federal Regulations, 2010 CFR

...2009-04-01 2009-04-01 false Gentamicin sulfate soluble powder. 520...NEW ANIMAL DRUGS § 520.1044c Gentamicin sulfate soluble powder. (a) Specifications. Each gram of gentamicin sulfate soluble powder...

2009-04-01

437

Linear shrinkage of metal powder compacts during sintering  

Microsoft Academic Search

The influence exerted by various factors (particle size, particle size distribution, ultrafine powder addition, sintering temperature, etc.) on the linear shrinkage ratio during sintering was examined. Electrolytic, atomized, and ultrafine copper powders, as well as electrolytic iron powder, were used.

H. H. Hausner; O. V. Roman

1965-01-01

438

21 CFR 522.1085 - Guaifenesin sterile powder.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 false Guaifenesin sterile powder. 522.1085 Section 522.1085 Food...DRUGS § 522.1085 Guaifenesin sterile powder. (a) Specifications. It is a sterile powder containing guaifenesin. (b)...

2013-04-01

439

21 CFR 520.2380f - Thiabendazole, piperazine phosphate powder.  

Code of Federal Regulations, 2013 CFR

... Thiabendazole, piperazine phosphate powder. 520.2380f Section 520.2380f... Thiabendazole, piperazine phosphate powder. (a) Specifications. Each ounce of water dispersible powder contains 6.67 grams of...

2013-04-01

440

21 CFR 520.763b - Dithiazanine iodide powder.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 false Dithiazanine iodide powder. 520.763b Section 520.763b ...DRUGS § 520.763b Dithiazanine iodide powder. (a) Chemical name. 3-Ethyl-2...Specifications. Dithiazanine iodide powder contains 200 milligrams of...

2013-04-01

441

21 CFR 872.6660 - Porcelain powder for clinical use.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 2013-04-01 false Porcelain powder for clinical use. 872.6660 Section...Miscellaneous Devices § 872.6660 Porcelain powder for clinical use. (a) Identification. Porcelain powder for clinical use is a device...

2013-04-01

442

21 CFR 520.1265 - Lincomycin and spectinomycin powder.  

Code of Federal Regulations, 2013 CFR

... false Lincomycin and spectinomycin powder. 520.1265 Section 520.1265 ...1265 Lincomycin and spectinomycin powder. (a) Specifications . The following...spectinomycin are present in a soluble powder in the ratio of 1 to 2 on the...

2013-04-01

443

21 CFR 520.2613 - Trimethoprim and sulfadiazine powder.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 false Trimethoprim and sulfadiazine powder. 520.2613 Section 520.2613 Food...520.2613 Trimethoprim and sulfadiazine powder. (a) Specifications. Each gram of powder contains 67 milligrams of trimethoprim...

2013-04-01

444

21 CFR 520.110 - Apramycin sulfate soluble powder.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 false Apramycin sulfate soluble powder. 520.110 Section 520.110 Food... § 520.110 Apramycin sulfate soluble powder. (a) Specifications. A water soluble powder used to make a medicated drinking...

2013-04-01

445

30 CFR 75.1101-18 - Dry powder requirements.  

Code of Federal Regulations, 2013 CFR

... 2013-07-01 2013-07-01 false Dry powder requirements. 75.1101-18 Section 75...MINES Fire Protection § 75.1101-18 Dry powder requirements. Each dry powder chemical system shall contain the following...

2013-07-01

446

49 CFR 173.170 - Black powder for small arms.  

Code of Federal Regulations, 2010 CFR

...The total quantity of black powder in one motor vehicle...vessel; (c) The black powder must be packed in inner metal or heavy wall conductive plastic receptacles not...must be marked “BLACK POWDER FOR SMALL ARMS” and “NA...

2010-10-01

447

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

PubMed

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

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

2013-05-01

448

CVD boron on calcium chromate powder  

SciTech Connect

This study was an experimental effort to improve the compositional homogeneity of a pyrotechnic mixture of boron and calcium chromate (CaCrO/sub 4/). Boron was deposited onto calcium chromate powders at 350/sup 0/C from a diborane and hydrogen gas mixture at a pressure of 40 torr by Chemical Vapor Deposition (CVD). The B:CaCrO/sub 4/ ratio of the coated powders was analyzed by inductively-coupled plasma spectroscopy and the distribution of the two phases was observed by electron microprobe analysis. The pyrotechnic activity was determined by differential thermal analysis. In addition to varying the composition of the mixture, an attempt was made to vary the boron distribution by coating both sized and unsized CaCrO/sub 4/ powders. Boron was deposited for 2 h onto sized CaCrO/sub 4/ powder, which resulted in a higher weight percentage of boron in comparison to the unsized powder. CVD coated CaCrO/sub 4/ powders began their pyrotechnic activity at an auto ignition temperature that was lower than the auto ignition temperature observed for mechanically blended mixtures. The coating of sized CaCrO/sub 4/ powder improved the uniformity of boron deposition of CaCrO/sub 4/, but it also decreased the pyrotechnic activity.

Coonen, R.M.

1984-09-01

449

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.

Evans, Douglas E.; Baron, Paul A.

2013-01-01

450

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

NASA Astrophysics Data System (ADS)

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

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

2008-03-01

451

Influence of carrier on the performance of dry powder inhalers.  

PubMed

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

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

2007-04-01

452

Electrical Resistivity of Metal Powder Aggregates  

NASA Astrophysics Data System (ADS)

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

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

2007-12-01

453

Powder metallurgy design manual, 2nd edition  

SciTech Connect

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

NONE

1995-12-31

454

Compatibility of header materials with pyrotechnic powder  

SciTech Connect

The intent of this research program is to qualify several stainless steels, nickel-base alloys and a titanium alloy as candidates for explosive component applications. This report focuses on the compatibility of these materials with pyrotechnic powder. The powder is a combined titanium subhydride-potassium perchlorate mixture, used both wet and dry. Hollow tensile bars were utilized to discern interactions between the metal and powder which underwent accelerated aging. Metallography was employed along with the mechanical property results to characterize the extent of interaction. No degradation in mechanical properties was noted. 6 figures, 6 tables.

Weirick, L.J.

1982-12-01

455

Enzyme-linked immunosorbent assay for the detection of bovine rennet whey powder in milk powder and buttermilk powder  

Microsoft Academic Search

An inhibition enzyme-linked immunosorbent assay (ELISA) for the detection of bovine rennet whey (BRW) solids in skim milk powders (SMP) and buttermilk powders is presented. The BRW content was determined in a neutralised trichloroacetic acid sample extract by binding of the dissolved caseinomacropeptide to an enzyme-labelled anti-bovine-?-casein monoclonal antibody. Calibration curves were constructed by analysing SMP standards with different known

Maria G. E. G. Bremer; Anna E. M. Kemmers-Voncken; Eduard A. M. Boers; Rob Frankhuizen; Willem Haasnoot

2008-01-01

456

Synthesis and structure analysis of aluminum doped zinc oxide powders  

Microsoft Academic Search

Hexagonal Al-doped zinc oxide (ZnO) powders with a nominal composition of Zn1?x\\u000a Al\\u000a x\\u000a O (0?x?0.028) were synthesized by the co-precipitation method. The contents of the Al element in the samples were measured by the\\u000a inductively coupled plasma-optical emission spectroscopy (ICP-OES) technique. The structures of the Zn1?x\\u000a Al\\u000a x\\u000a O (0?x?0.028) compounds calcined at 1000 and 1200°C have been determined

DengPan Nie; Tao Xue; Yu Zhang; XiangJun Li

2008-01-01

457

The technology and commercial status of powder-injection molding  

NASA Astrophysics Data System (ADS)

The process of powder-injection molding (PIM) is a viable and competitive commercial technique that is being used to process complex-shaped parts of various materials in moderate to high volumes. The hey advantage of the process is its unique ability to combine materials selection flexibility with the complex shape-forming ability of plastics. Although the PIM process has been discussed in the open literature for more than quarter of a century, it has become a commercial reality only during the last decade or so. Currently, there is a tremendous interest in this unique technology throughout the world. As a result, the PIM industry is poised for significant growth.

Bose, Animesh

1995-08-01

458

Preparation of Al 2O 3–TiB 2 nanocomposite powder by mechanochemical reaction between Al, B 2O 3 and Ti  

Microsoft Academic Search

Mechanochemical processing is a novel technique for the synthesis of nano-sized materials. This research is based on the production of Al2O3–TiB2 nanocomposite powder using mechanochemical processing. For this purpose, a mixture of aluminum, titanium and boron oxide powders was subjected to high energy ball milling. The structural evaluation of powder particles after different milling times was conducted by X-ray diffractometry

E. Mohammad Sharifi; F. Karimzadeh; M. H. Enayati

2011-01-01

459

Magnetofluidization of fine magnetite powder  

NASA Astrophysics Data System (ADS)

The behavior of a fluidized bed of fine magnetite particles as affected by a cross-flow magnetic field is investigated. A distinct feature of this naturally cohesive powder, as compared to noncohesive magnetic grains usually employed in magnetofluidized beds, is that the fluidized bed displays a range of stable fluidization even in the absence of an external magnetic field. Upon application of the magnetic field, the interval of stable fluidization is extended to higher gas velocities and bed expansion is enhanced. We have measured the tensile strength as affected by application of the external magnetic field according to two different operation modes. In the H off-on operation mode, the bed is driven to bubbling in the absence of external magnetic field. Once the gas velocity is decreased below the bubbling onset and the bed has returned to stable fluidization due to natural cohesive forces, the field is applied. In the H on-on mode, the field is maintained during the whole process of bubbling and return to stable fluidization. It is found that the tensile strength of the naturally stabilized bed is not essentially changed by application of the field ( H off-on) since the magnetic field cannot alter the bed structure once the particles are jammed in the stable fluidization state. Magnetic forces within the bulk of the jammed bed are partially canceled as a result of the anisotropic nature of the dipole-dipole interaction between the particles, which gives rise to just a small increment of the tensile strength. On the other hand, when the field is held on during bubbling and transition to stable fluidization ( H on-on mode), the tensile strength is appreciably increased. This suggests the formation of particle chains when the particles are not constrained due to the dipole-dipole attractive interaction which affects the mechanical strength of the stably fluidized bed. Experimental data are analyzed in the light of theoretical models on magnetic surface stresses.

Valverde, J. M.; Espin, M. J.; Quintanilla, M. A. S.; Castellanos, A.

2009-03-01

460

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

461

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

462

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

463

Dynamic Compaction of Metal and Ceramic Powders.  

National Technical Information Service (NTIS)

The state of the art and the technological potential for the dynamic consolidation of metal and ceramic powders were assessed. Fundamental consideration of dynamic consolidation, consolidation phenomena during dynamic compaction, dynamic compaction and co...

V. D. Linse O. R. Bergmann C. F. Cline J. D. Mote H. Palmour

1983-01-01

464

LaRC dry powder towpreg process  

NASA Technical Reports Server (NTRS)

The dry powder towpreg process overcomes many of the difficulties associated with melt, solution and slurry prepregging of advanced composite materials. In the process, fluidized powder is deposited on spread tow bundles and melted on the fibers by radiant heating to adhere the polymer to the fiber. Bench scale design and operating data have been correlated for use in process scale up to commercial operation. Powdered towpreg has been woven and molded into preform material of good quality. Cost estimates suggest that processing costs are comparable to those of conventional hot melt prepreg. In the future, from a part fabrication point of view, powder coated prepreg tape, woven broad goods and woven and braided preforms may be considered as options to similar materials made by other methods.

Marchello, Joseph M.; Baucom, Robert M.

1991-01-01

465

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

466

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

467

Sonochemical synthesis of calcium phosphate powders.  

PubMed

beta-tricalcium phosphate (beta-TCP) and biphasic calcium phosphate powders (BCP), consisting of hydroxyapatite (HA) and beta-TCP, were synthesized by thermal decomposition of precursor powders obtained from neutralization method. The precursor powders with a Ca/P molar ratio of 1.5 were prepared by adding an orthophosphoric acid (H(3)PO(4)) solution to an aqueous suspension containing calcium hydroxide (Ca(OH)(2)). Mixing was carried out by vigorous stirring and under sonochemical irradiation at 50 kHz, respectively. Glycerol and D-glucose were added to evaluate their influence on the precipitation of the resulting calcium phosphate powders. After calcination at 1000 degrees C for 3 h BCP nanopowders of various HA/beta-TCP ratio were obtained. PMID:17136604

de Campos, M; Müller, F A; Bressiani, A H A; Bressiani, J C; Greil, P

2007-05-01

468

Continuation of a Reactive Alumina Powder.  

National Technical Information Service (NTIS)

Dry ball milling and milling in several liquid media were investigated as means of reducing reactive alumina powders containing porous aggregates to their ultimate particle size. Milling in liquid media eliminated the porous aggregates, but denser aggrega...

R. B. Bennett D. E. Niesz

1971-01-01

469

Advances in food powder agglomeration engineering.  

PubMed

Food powders are used in everyday life in many ways and offer technological solutions to the problem of food production. The natural origin of food powders, diversity in their chemical composition, variability of the raw materials, heterogeneity of the native structures, and physicochemical reactivity under hydrothermal stresses contribute to the complexity in their behavior. Food powder agglomeration has recently been considered according to a multiscale approach, which is followed in the chapter layout: (i) at the particle scale, by a presentation of particle properties and surface reactivity in connection with the agglomeration mechanisms, (ii) at the mechanisms scale, by describing the structuration dynamics of agglomerates, (iii) at the process scale, by a presentation of agglomeration technologies and sensors and by studying the stress transmission mode in the powder bed, and finally (iv) by an integration of the acquired knowledge, thanks to a dimensional analysis carried out at each scale. PMID:23522795

Cuq, B; Gaiani, C; Turchiuli, C; Galet, L; Scher, J; Jeantet, R; Mandato, S; Petit, J; Murrieta-Pazos, I; Barkouti, A; Schuck, P; Rondet, E; Delalonde, M; Dumoulin, E; Delaplace, G; Ruiz, T

2013-01-01

470

Synthesis and properties of a ? composite powder  

NASA Astrophysics Data System (ADS)

A powder of nominal composition 4 mol 0953-2048/10/11/011/img12 (Bi-2212) + 1 mol 0953-2048/10/11/011/img13 was prepared from acetates by a sol - gel method. When compared with a conventional Bi-2212 powder, the composite powder was less phase pure, containing significant concentrations of 0953-2048/10/11/011/img14, Cu-free phases, and CuO. Electron microscopy revealed the presence of nanometre-scale precipitates within many of the superconductor grains in the composite powder. Although these precipitates were uniformly distributed in only some of the superconducting grains, enhancement of flux pinning at 6 K was attributed to their presence.

Goretta, K. C.; Xu, Y.; Cook, R. E.; Feng, L. R.; Deptula, A.; Lada, W.; Olczak, T.; Xu, M.; Balachandran, U.

1997-11-01

471

Synthesis and processing of monosized oxide powders  

DOEpatents

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

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

1985-09-24

472

Electrical Resistivity of Metal Powder Aggregates  

Microsoft Academic Search

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

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

2007-01-01

473

Drying powders for crucibles of induction furnaces  

Microsoft Academic Search

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

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

1980-01-01

474

Synthesis of yttria powders by electrospray pyrolysis  

Microsoft Academic Search

Electrospray atomization of high-concentration ([approximately]400 g\\/L) chemical precursor solutions was applied to the synthesis of yttria powders. Conditions were found which led to high-quality powders, composed of dense, spheroidal, submicrometer, and nanocrystalline oxide particles. The precursor solutions were hydrated yttrium nitrates dissolved in n-propyl alcohol at concentrations ranging from 44.1 to 455 g\\/L. Electrospray atomization produced submicrometer precursor droplets which

Aaron J. Rulison; Richard C. Flagan

1994-01-01

475

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

476

Electron beam sintering of metal powder  

Microsoft Academic Search

The laser is widely used in additive layer manufacturing for producing parts on the basis of polymer and metal powder. In\\u000a the metal area, the capacity of laser technologies is noticeably exhausted. The electron beam (eb) technology offers higher\\u000a power density and beam velocity and therefore seems more suitable for sintering high-tensile steel powder in an economic way.\\u000a In this

J. Milberg; M. Sigl

2008-01-01

477

Biaxially textured articles formed by powder metallurgy  

DOEpatents

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

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

2001-01-01

478

Method and Apparatus for Production of Powders  

NASA Technical Reports Server (NTRS)

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

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

1998-01-01

479

Method and apparatus for production of powders  

NASA Technical Reports Server (NTRS)

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

Stolzfus, Joel M. (inventor.); Sircar, Subhasish (inventor.)

1995-01-01

480

Feedstock development for micro powder injection molding  

Microsoft Academic Search

Powder injection molding of microstructured parts with high aspect ratios requires feedstocks, which have a high mechanical\\u000a stability for demolding. The binders of the feedstocks have to allow pressure free and complete debinding and sintering without\\u000a deformation in the submillimeter range. For complete molding of especially small and complex detailed microstructures, powders\\u000a with a small particle size have to be

L. Merz; S. Rath; V. Piotter; R. Ruprecht; J. Ritzhaupt-Kleissl; J. Hausselt

2002-01-01

481

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

482

Densification of powder compacts by vibration  

Microsoft Academic Search

Various packing methods such as vibration, shaking, etc., in addition to normal gravitational settling, can be often used\\u000a to density powder compacts. Many issues relevant to this matter are of great importance in advanced ceramic powder processing.\\u000a In the present work, the relaxation of structure due to vibration is addressed by using a computer experimental model based\\u000a on Monte Carlo

Hern Kim; Moo-Sil Pyun

1995-01-01

483

Magnetoresistance of Chromium Dioxide Powder Compacts  

Microsoft Academic Search

Cold-pressed powders of the half-metallic ferromagnet CrO2 are dielectric granular metals. Hysteretic magnetoresistance with maxima at the coercive field arises from interparticle contacts. Dilution with insulating antiferromagnetic Cr2O3 powder reduces the conductivity by 3 orders of magnitude, but enhances the magnetoresistance ratio which reaches 50% at 5K. The negative magnetoresistance is due to tunneling between contiguous ferromagnetic particles along a

J. M. D. Coey; A. E. Berkowitz; Ll. Balcells; F. F. Putris; A. Barry

1998-01-01

484

Magnetoresistance of Chromium Dioxide Powder Compacts  

NASA Astrophysics Data System (ADS)

Cold-pressed powders of the half-metallic ferromagnet CrO2 are dielectric granular metals. Hysteretic magnetoresistance with maxima at the coercive field arises from interparticle contacts. Dilution with insulating antiferromagnetic Cr2O3 powder reduces the conductivity by 3 orders of magnitude, but enhances the magnetoresistance ratio which reaches 50% at 5K. The negative magnetoresistance is due to tunneling between contiguous ferromagnetic particles along a critical path with a spin-dependent Coulomb gap.

Coey, J. M. D.; Berkowitz, A. E.; Balcells, Ll.; Putris, F. F.; Barry, A.

1998-04-01

485

Moisture sorption studies on onion powder  

Microsoft Academic Search

Moisture sorption studies were conducted on three samples of onion powders, i.e. freeze-dried, vacuum shelf-dried and through flow-dried onions. The data obtained for texture (flowability) and per cent moisture were used in determining critical moisture levels. The monolayer moisture contents, corresponding to Brunauer Emmett Teller (BET) theory were taken as the safe minimum moisture levels in onion powder. The moisture

Sukumar Debnath; J Hemavathy; K. K Bhat

2002-01-01

486

Asymmetric rolling of metal powders and granules  

Microsoft Academic Search

The paper examines asymmetric rolling of aluminum powder and granules on driving rolls of different diameters at the same\\u000a angular velocity. The ratio of roll diameters is 1.1 to 1.4. It is established that asymmetric rolling of powder material\\u000a allows removing drawbacks peculiar to traditional asymmetric rolling. These drawbacks are roll camber and destruction caused\\u000a by nonuniform distribution of contact

G. Ya. Kalutskii; K. A. Gogaev; V. S. Voropaev; V. V. Nepomnyashchii

2007-01-01

487

Flexible dielectric waveguides with powder cores  

Microsoft Academic Search

Flexible dielectric waveguides have been demonstrated at 10 GHz and 94 GHz using thin-wall polymer tubing filled with low-loss, high-dielectric-constant powders. Absorptive losses of the order of 10 dB\\/m were measured at 94 GHz with nickel-aluminum titanate and barium tetratitanate powder in polytetrafluoroethylene (PTFE) lightweight electrical tubing. Bending losses at 94 GHz were negligible for curvature radii greater than 4

William M. Bruno; William B. Bridges

1988-01-01

488

Powder injection moulding of premixed ferritic and austenitic stainless steel powders  

Microsoft Academic Search

In this experimental work, powder injection moulding (PIM) of premixed 316L and 430L gas-atomized powders was developed to obtain duplex stainless steels. A multicomponent binder constituted of high density polyethylene (HDPE) and paraffin wax (PW) in a volume ratio 50\\/50 was selected for the process. Feedstocks with powder loadings of 50, 65, 68 and 70vol.% were prepared. Mixing experiments were

M. E. Sotomayor; B. Levenfeld; A. Várez

2011-01-01

489

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

490

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

PubMed

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

Okumura, Takehiro; Otsuka, Makoto

2005-05-01

491

Electrical conductivity of metal powders under pressure  

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

492

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