Science.gov

Sample records for mg-based amorphous ball-milled

  1. Athermal character of the solid state amorphization of lactose induced by ball milling

    NASA Astrophysics Data System (ADS)

    Willart, J. F.; Caron, V.; Lefort, R.; Danède, F.; Prévost, D.; Descamps, M.

    2004-12-01

    In this paper, we report the possibility to reach pure glassy amorphous lactose by ball milling of crystalline α lactose under a dry nitrogen atmosphere. This route to the glassy state is found to be free of mutarotation towards the anomer β while this mutarotation is unavoidable using the usual thermal route, i.e. the quench of the liquid. This result definitely makes the 'local quench melting' hypothesis unsuitable to account for amorphization by ball milling.

  2. Amorphous solid dispersions of sulfonamide/Soluplus® and sulfonamide/PVP prepared by ball milling.

    PubMed

    Caron, Vincent; Hu, Yun; Tajber, Lidia; Erxleben, Andrea; Corrigan, Owen I; McArdle, Patrick; Healy, Anne Marie

    2013-03-01

    The aim of this paper is to investigate the physicochemical properties of binary amorphous dispersions of poorly soluble sulfonamide/polymeric excipient prepared by ball milling. The sulfonamides selected were sulfathiazole (STZ), sulfadimidine (SDM), sulfamerazine (SMZ) and sulfadiazine (SDZ). The excipients were polyvinylpyrrolidone (PVP) and polyvinyl caprolactam-polyvinyl acetate-polyethylene glycol graft co-polymer, commercially known as Soluplus®. Co-milled systems were characterised by powder X-ray diffraction and differential scanning calorimetry. PVP was shown to form amorphous dispersions over a wider composition range than Soluplus® for the four sulfonamides tested. Moreover, amorphous dispersions made with PVP were homogeneous [single glass transition (Tg)], while amorphous dispersions made from Soluplus® were heterogeneous (two Tgs). This behaviour is consistent with the fact that all the sulfonamides tested presented a lower solubility in Soluplus® than in PVP, as evidenced by Flory-Huggins parameters determined. Amorphous dispersions of SDM with Soluplus® could be produced even though SDM does not amorphise alone upon milling and Soluplus® presents Tg at a lower temperature than SDM. Amorphous dispersions of SMZ could be prepared with a lower excipient concentration compared to STZ, SDM and SDZ, which may reflect the one-dimensional H-bonding network in SMZ compared to the 2D or 3D H-bonding network found in the other sulfonamides. Stability tests (60% RH/25°C) revealed that dispersions made with Soluplus® remained dry and powdery compared to those made with PVP that formed a sticky paste in less than 2 weeks, indicating a possible advantage of using Soluplus® in terms of increased physical stability under high humidity storage conditions.

  3. On the amorphization behavior and hydrogenation performance of high-energy ball-milled Mg{sub 2}Ni alloys

    SciTech Connect

    Kou, Hongchao; Hou, Xiaojiang; Zhang, Tiebang Hu, Rui; Li, Jinshan; Xue, Xiangyi

    2013-06-15

    Amorphous Mg{sub 2}Ni alloy was prepared by high energy ball-milling starting with polycrystalline Mg{sub 2}Ni which was prepared with the help of a metallurgy method by using a SPEX 8000D mill. The microstructural and phase structure characterization of the prepared materials was performed via scanning electron microscopy, transition electron microscope and X-ray diffraction. The thermal stabilities were investigated by differential scanning calorimetry. The apparent activation energies were determined by means of the Kissinger method. The first and second crystallization reactions take place at ∼ 255 °C and ∼ 410 °C, and the corresponding activation energy of crystallization is E{sub a1} = 276.9 and E{sub a2} = 382.4 kJ/mol, respectively. At 3 MPa hydrogen pressure and 250 °C, the hydrogen absorption capacities of crystalline, partially and fully amorphous Mg{sub 2}Ni alloy are 2.0 wt.%, 3.2 wt.% and 3.5 wt.% within 30 min, respectively. - Graphical Abstract: We mainly focus on the amorphization behavior of crystalline Mg{sub 2}Ni alloy in the high energy ball-milling process and the crystallization behavior of the amorphous Mg{sub 2}Ni alloy in a follow-up heating process. The relationship of milling, microstructure and hydrogenation properties is established and explained by models. - Highlights: • Amorphous Mg{sub 2}Ni has been obtained by high energy ball milling the as-cast alloy. • The amorphization behavior of polycrystalline Mg{sub 2}Ni is presented. • The crystallization behavior of the amorphous Mg{sub 2}Ni alloy is illustrated. • Establish the relationship of milling, microstructure and hydrogenation properties.

  4. Effect of ball milling on the physicochemical properties of atorvastatin calcium sesquihydrate: the dissolution kinetic behaviours of milled amorphous solids.

    PubMed

    Kobayashi, Makiko; Hattori, Yusuke; Sasaki, Tetsuo; Otsuka, Makoto

    2017-01-01

    The purposes of this study were to clarify the amorphization by ball milling of atorvastatin calcium sesquihydrate (AT) and to analyse the change in dissolution kinetics. The amorphous AT was prepared from crystal AT by ball milling and analysed in terms of the changes of its physicochemical properties by powder X-ray diffraction analysis (XRD), thermal analysis and infrared spectroscopy (IR). Moreover, to evaluate the usefulness of the amorphous form for pharmaceutical development, intrinsic solubility of the ground product was evaluated using a dissolution kinetic method. The XRD results indicated that crystalline AT was transformed into amorphous solids by more than 30-min milling. The thermal analysis result suggested that chemical potential of the ground AT are changed significantly by milling. The IR spectra of the AT showed the band shift from the amide group at 3406 cm(-1) with an intermolecular hydrogen bond to a free amide group at 3365 cm(-1) by milling. The dissolution of amorphous AT follows a dissolution kinetic model involving phase transformation. The initial dissolution rate of the ground product increased with the increase in milling time to reflect the increase in the intrinsic solubility based on the amorphous state. © 2016 Royal Pharmaceutical Society.

  5. High performance amorphous-Si@SiOx/C composite anode materials for Li-ion batteries derived from ball-milling and in situ carbonization

    NASA Astrophysics Data System (ADS)

    Wang, Dingsheng; Gao, Mingxia; Pan, Hongge; Wang, Junhua; Liu, Yongfeng

    2014-06-01

    Amorphous-Si@SiOx/C composites with amorphous Si particles as core and coated with a double layer of SiOx and carbon are prepared by ball-milling crystal micron-sized silicon powders and carbonization of the citric acid intruded in the ball-milled Si. Different ratios of Si to citric acid are used in order to optimize the electrochemical performance. It is found that SiOx exists naturally at the surfaces of raw Si particles and its content increases to ca. 24 wt.% after ball-milling. With an optimized Si to citric acid weight ratio of 1/2.5, corresponding to 8.4 wt.% C in the composite, a thin carbon layer is coated on the surfaces of a-Si@SiOx particles, moreover, floc-like carbon also forms and connects the carbon coated a-Si@SiOx particles. The composite provides a capacity of 1450 mA h g-1 after 100 cycles at a current density of 100 mA g1, and a capacity of 1230 mA h g-1 after 100 cycles at 500 mA g1 as anode material for lithium-ion batteries. Effects of ball-milling and the addition of citric acid on the microstructure and electrochemical properties of the composites are revealed and the mechanism of the improvement in electrochemical properties is discussed.

  6. Structural changes during high-energy ball milling of iron-based amorphous alloys: Is high-energy ball milling equivalent to a thermal process\\?

    NASA Astrophysics Data System (ADS)

    Trudeau, M. L.; Schulz, R.; Dussault, D.; van Neste, A.

    1990-01-01

    We report the first study of the effect of high-energy mechanical deformation on amorphous iron-based metallic alloys. The structural changes happening in amorphous iron-based materials containing Co or Ni during mechanical deformation show that the structural stability of an amorphous alloy against a thermal and a mechanical process are not related. Therefore, the concept of a high local effective temperature during the milling process cannot be singled out as the only reason for the observed structural transformations.

  7. Polymorphic form of piroxicam influences the performance of amorphous material prepared by ball-milling.

    PubMed

    Naelapää, Kaisa; Boetker, Johan Peter; Veski, Peep; Rantanen, Jukka; Rades, Thomas; Kogermann, Karin

    2012-06-15

    The objective of this study was to investigate the influence of the starting solid state form of piroxicam (anhydrate form I: PRXAH I vs form II: PRXAH II) on the properties of the resulting amorphous material. The second objective was to obtain further insight into the impact of critical factors like thermal stress, dissolution medium and storage conditions on the thermal behavior, solid state transformations and physical stability of amorphous materials. For analysis differential scanning calorimetry (DSC), Raman spectroscopy and X-ray powder diffractometry (XRPD) were used. Pair-wise distribution function (PDF) analysis of the XRPD data was performed. PDF analysis indicated that the recrystallization behavior of amorphous samples was influenced by the amount of residual order in the samples. The recrystallization behavior of amorphous samples prepared from PRXAH I showed similarity to the starting material, whereas the recrystallization behavior of amorphous samples prepared from PRXAH II resembled to that of the PRX form III (PRXAH III). Multivariate data analysis (MVDA) helped to identify that the influence of storage time and temperature was more pronounced in the case of amorphous PRX prepared from PRXAH I. Furthermore, the wet slurry experiments with amorphous materials revealed the recrystallization of amorphous material as PRXMH in the biorelevant medium.

  8. Mg-based amorphous alloys for decolorization of azo dyes

    NASA Astrophysics Data System (ADS)

    Zhang, Changqin; Zhu, Zhengwang; Zhang, Haifeng

    The authors recently found that Mg-based amorphous ribbons had a prominent effect on the decolorization of azo dyes. Direct Blue 2B and Acid Orange II solutions of 100 mg/L could be decolorized nearly completely by the ribbons within 30 min. Decolorization mechanism was discussed briefly, and kinetic analysis based on the experimental data indicated that physical adsorption and reductive degradation for the azo dye solutions mediated by Mg63Cu16.8Ag11.2Er9 amorphous ribbons could proceed in an elegant and rapid manner. This new finding seems attractive, valuable and promising for the raw effluent generated by textile dye manufacturing company in the future.

  9. Ball-milling of graphite and muilti-wall carbon nanotubes.

    PubMed

    Nam, Hye Rim; Kim, Young Jin; Yang, Sang Sun; Ahn, Jung-Ho

    2014-12-01

    The structural modification of graphite and multi-wall carbon nanotubes (MWCNTs) during ball-milling was examined. A comparison of structures after ball-milling was made between graphite and MWCNTs. The ball milling parameters were also examined: milling atmospheres, milling methods, milling mode and the addition of additive materials. In some experiments, hard materials such as alumina or silica were added to graphite and MWCNTs as additives to see whether graphite and MWCTs were shortened by ball-milling. The ball-milling of graphite and MWCNTs with liquid additives reduced the agglomeration of MWCNT and transformed graphite to graphenes. The ball-milling of MWCNTs under impact mode usually resulted in the formation of an amorphous phase, whereas that under friction mode induced the fattening of nanotubes. The results showed that a variety of carbon nanomaterials could be obtained by the proper controlling of ball milling. The structurally modified graphite and MWSNTs are expected to be utilized for energy storage application.

  10. Microstructural Evolution, Thermodynamics, and Kinetics of Mo-Tm₂O₃ Powder Mixtures during Ball Milling.

    PubMed

    Luo, Yong; Ran, Guang; Chen, Nanjun; Shen, Qiang; Zhang, Yaoli

    2016-10-15

    The microstructural evolution, thermodynamics, and kinetics of Mo (21 wt %) Tm₂O₃ powder mixtures during ball milling were investigated using X-ray diffraction and transmission electron microscopy. Ball milling induced Tm₂O₃ to be decomposed and then dissolved into Mo crystal. After 96 h of ball milling, Tm₂O₃ was dissolved completely and the supersaturated nanocrystalline solid solution of Mo (Tm, O) was obtained. The Mo lattice parameter increased with increasing ball-milling time, opposite for the Mo grain size. The size and lattice parameter of Mo grains was about 8 nm and 0.31564 nm after 96 h of ball milling, respectively. Ball milling induced the elements of Mo, Tm, and O to be distributed uniformly in the ball-milled particles. Based on the semi-experimental theory of Miedema, a thermodynamic model was developed to calculate the driving force of phase evolution. There was no chemical driving force to form a crystal solid solution of Tm atoms in Mo crystal or an amorphous phase because the Gibbs free energy for both processes was higher than zero. For Mo (21 wt %) Tm₂O₃, it was mechanical work, not the negative heat of mixing, which provided the driving force to form a supersaturated nanocrystalline Mo (Tm, O) solid solution.

  11. The Influence of Ball-milling on Structural and Magnetic Properties of Co-based Powders

    NASA Astrophysics Data System (ADS)

    Degmová, J.; Tóth, I.; Bednarčík, J.; Kollár, P.

    2005-07-01

    The melt-spun Co- and Fe-based amorphous alloys have been investigated extensively for applications in magnetic devices, which require magnetically soft materials. Although these alloys exhibit excellent soft magnetic properties, their thin sheet shape, which is a consequence of the low glass forming ability, limits significantly their engineering applications. A powder metallurgy is thus an alternative way of producing bulk and, at the same time, soft magnetic materials, having desired shape. In our case, Co56Fe16Zr8B20 and Co70.3Fe4.7Si10B15 amorphous ribbons have been ball-milled for a short time and subsequently compacted (by hot pressing) into disc-shaped specimens with the aim to achieve samll values of resulting coercivity. This work is focused only on the first preparation step i.e. on structural and magnetic properties of ball-milled powders obtained by ball-milling of Co-based melt-spun ribbons at different conditions. Two different ways of milling were employed in order to obtain a powder form of the material: the ribbons were either continuously ball-milled for up to 12 hours or, after each half an hour of ball-milling, the vials were cooled in liquid nitrogen bath for half an hour. Mössbauer spectroscopy, X-ray diffraction and differential scanning calorimetry were employed to compare and to present the differences between these two different ways of milling.

  12. Magnetic properties of ball-milled SrFe12O19 particles consolidated by Spark-Plasma Sintering

    PubMed Central

    Stingaciu, Marian; Topole, Martin; McGuiness, Paul; Christensen, Mogens

    2015-01-01

    The room-temperature magnetic properties of ball-milled strontium hexaferrite particles consolidated by spark-plasma sintering are strongly influenced by the milling time. Scanning electron microscopy revealed the ball-milled SrFe12O19 particles to have sizes varying over several hundred nanometers. X-Ray powder-diffraction studies performed on the ball-milled particles before sintering clearly demonstrate the occurrence of a pronounced amorphization process. During sintering at 950 oC, re-crystallization takes place, even for short sintering times of only 2 minutes and transformation of the amorphous phase into a secondary phase is unavoidable. The concentration of this secondary phase increases with increasing ball-milling time. The remanence and maximum magnetization values at 1T are weakly influenced, while the coercivity drops dramatically from 2340 Oe to 1100 Oe for the consolidated sample containing the largest amount of secondary phase. PMID:26369360

  13. Magnetic properties of ball-milled SrFe12O19 particles consolidated by Spark-Plasma Sintering.

    PubMed

    Stingaciu, Marian; Topole, Martin; McGuiness, Paul; Christensen, Mogens

    2015-09-15

    The room-temperature magnetic properties of ball-milled strontium hexaferrite particles consolidated by spark-plasma sintering are strongly influenced by the milling time. Scanning electron microscopy revealed the ball-milled SrFe12O19 particles to have sizes varying over several hundred nanometers. X-Ray powder-diffraction studies performed on the ball-milled particles before sintering clearly demonstrate the occurrence of a pronounced amorphization process. During sintering at 950 °C, re-crystallization takes place, even for short sintering times of only 2 minutes and transformation of the amorphous phase into a secondary phase is unavoidable. The concentration of this secondary phase increases with increasing ball-milling time. The remanence and maximum magnetization values at 1T are weakly influenced, while the coercivity drops dramatically from 2340 Oe to 1100 Oe for the consolidated sample containing the largest amount of secondary phase.

  14. Microstructural Evolution, Thermodynamics, and Kinetics of Mo-Tm2O3 Powder Mixtures during Ball Milling

    PubMed Central

    Luo, Yong; Ran, Guang; Chen, Nanjun; Shen, Qiang; Zhang, Yaoli

    2016-01-01

    The microstructural evolution, thermodynamics, and kinetics of Mo (21 wt %) Tm2O3 powder mixtures during ball milling were investigated using X-ray diffraction and transmission electron microscopy. Ball milling induced Tm2O3 to be decomposed and then dissolved into Mo crystal. After 96 h of ball milling, Tm2O3 was dissolved completely and the supersaturated nanocrystalline solid solution of Mo (Tm, O) was obtained. The Mo lattice parameter increased with increasing ball-milling time, opposite for the Mo grain size. The size and lattice parameter of Mo grains was about 8 nm and 0.31564 nm after 96 h of ball milling, respectively. Ball milling induced the elements of Mo, Tm, and O to be distributed uniformly in the ball-milled particles. Based on the semi-experimental theory of Miedema, a thermodynamic model was developed to calculate the driving force of phase evolution. There was no chemical driving force to form a crystal solid solution of Tm atoms in Mo crystal or an amorphous phase because the Gibbs free energy for both processes was higher than zero. For Mo (21 wt %) Tm2O3, it was mechanical work, not the negative heat of mixing, which provided the driving force to form a supersaturated nanocrystalline Mo (Tm, O) solid solution. PMID:28773955

  15. Ball milling synthesis of silica nanoparticle from rice husk ash for drug delivery application.

    PubMed

    Salavati-Niasari, Masoud; Javidi, Jaber; Dadkhah, Mahnaz

    2013-07-01

    Silica nanoparticles were synthesized from rice husk ash at room temperature by using high energy planetary ball mill. The milling time and mill rotational speed were varied in four levels. The morphology of the synthesized powders was investigated by the FE-SEM and TEM image as well as XRD patterns. The results have revealed that the nano-sized amorphous silica particles are formed after about 6 h ball milling and they are spherical in shape. The average particle size of the silica powders is found to be around 70 nm which decreases with increasing ball milling time or mill rotational speed. The as-synthesized silica nanoparticles were subsequently employed as drug carrier to investigate in vitro release behavior of Penicillin-G in simulated body fluid. UV-Vis spectroscopy was used to determine the amount of Penicillin-G released from the carrier. Penicillin-G release profile from silica nanoparticles exhibited a delayed release effect.

  16. Comprehensive characterization of ball-milled powders simulating a tribofilm system

    SciTech Connect

    Häusler, I. Dörfel, I. Peplinski, B. Dietrich, P.M. Unger, W.E.S. Österle, W.

    2016-01-15

    A model system was used to simulate the properties of tribofilms which form during automotive braking. The model system was prepared by ball milling of a blend of 70 vol.% iron oxides, 15 vol.% molybdenum disulfide and 15 vol.% graphite. The resulting mixture was characterized by X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and various transmission electron microscopic (TEM) methods, including energy dispersive X-ray spectroscopy (EDXS), high resolution investigations (HRTEM) with corresponding simulation of the HRTEM images, diffraction methods such as scanning nano-beam electron diffraction (SNBED) and selected area electron diffraction (SAED). It could be shown that the ball milling caused a reduction of the grain size of the initial components to the nanometer range. Sometimes even amorphization or partial break-down of the crystal structure was observed for MoS{sub 2} and graphite. Moreover, chemical reactions lead to a formation of surface coverings of the nanoparticles by amorphous material, molybdenum oxides, and iron sulfates as derived from XPS. - Highlights: • Ball milling of iron oxides, MoS{sub 2}, and graphite to simulate a tribofilm • Increasing coefficient of friction after ball milling of the model blend • Drastically change of the diffraction pattern of the powder mixture • TEM & XPS showed the components of the milled mixture and the process during milling. • MoS{sub 2} and graphite suffered a loss in translation symmetry or became amorphous.

  17. Formation of budesonide/α-lactose glass solutions by ball-milling

    NASA Astrophysics Data System (ADS)

    Dudognon, E.; Willart, J. F.; Caron, V.; Capet, F.; Larsson, T.; Descamps, M.

    2006-04-01

    The possibility to obtain amorphous budesonide stabilised by blending with an excipient characterised by a higher glass transition temperature, namely α-lactose, has been studied. We carried out the mixing of the two compounds at room temperature by ball-milling. The four obtained blends (containing, respectively, 10, 30, 50 and 70% w of budesonide) are X-ray amorphous and exhibit a single glass transition located between the ones of pure milled crystalline compounds. This revealed that the two amorphous phases are miscible whatever the composition and sufficiently mixed to relax as a whole. Ball-milling thus appears as a powerful tool to form amorphous molecular alloys with enhanced stability properties.

  18. Multifractal properties of ball milling dynamics

    SciTech Connect

    Budroni, M. A. Pilosu, V.; Rustici, M.; Delogu, F.

    2014-06-15

    This work focuses on the dynamics of a ball inside the reactor of a ball mill. We show that the distribution of collisions at the reactor walls exhibits multifractal properties in a wide region of the parameter space defining the geometrical characteristics of the reactor and the collision elasticity. This feature points to the presence of restricted self-organized zones of the reactor walls where the ball preferentially collides and the mechanical energy is mainly dissipated.

  19. DETAIL VIEW OF BALL MILL FEED SYSTEM, MOUTH OF CLASSIFIER, ...

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

    DETAIL VIEW OF BALL MILL FEED SYSTEM, MOUTH OF CLASSIFIER, AND ORE BIN CHUTE, LOOKING EAST NORTHEAST. CRUSHED ORE FROM THE SECONDARY ORE BIN WAS INTRODUCED INTO THE FEED TROUGH VIA A CHUTE. AS THE BALL MILL TURNED, THE ROUND SCOOP ALSO TURNED IN THE TROUGH TO CHANNEL ORE INTO THE BALL MILL. SEE CA-292-20 (CT) FOR IDENTICAL COLOR TRANSPARENCY. - Gold Hill Mill, Warm Spring Canyon Road, Death Valley Junction, Inyo County, CA

  20. DETAIL VIEW OF BALL MILL FEED SYSTEM, MOUTH OF CLASSIFIER, ...

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

    DETAIL VIEW OF BALL MILL FEED SYSTEM, MOUTH OF CLASSIFIER, AND ORE BIN CHUTE, LOOKING EAST NORTHEAST. CRUSHED ORE FROM THE SECONDARY ORE BIN WAS INTRODUCED INTO THE FEED TROUGH VIA A CHUTE. AS THE BALL MILL TURNED, THE ROUND SCOOP ALSO TURNED IN THE TROUGH TO CHANNEL ORE INTO THE BALL MILL. SEE CA-292-14 FOR IDENTICAL B&W NEGATIVE. - Gold Hill Mill, Warm Spring Canyon Road, Death Valley Junction, Inyo County, CA

  1. Microstructure investigations of ball milled materials.

    PubMed

    Huang, J Y; Wu, Y K; Ye, H Q

    1998-01-15

    HREM and FEG TEM were emphasized and extensively used to follow the most subtle changes in the structure and composition of ball-milled Cu, Fe-Cu, and thermally decomposed Fe60Cu40. Some significant results are obtained and summarized as follows: HREM shows that the deformation of ball-milled copper proceeds mainly by twinning and shear bands (SBs) formation. The nano-grains formed during ball milling (BM) contain a high density of dislocations. The grain boundaries (GBs) of nanocrystalline (NC) Cu prepared by BM are ordered, curved, and strained, but disordering, lattice distortion, and nanovoids in local regions were frequently observed. Nanoscale composition analysis on mechanically alloyed Fe16Cu84 shows that the average Fe content in both the interior of grains and the GBs is close to the designed composition, which proves that a supersaturated solid solution has really formed. However, the Fe content is rather inhomogeneous between the larger and smaller grains, which infers the inhomogeneous mixing of Fe and Cu during mechanical alloying (MA). NC structure and the mechanical force-enhanced fast diffusion are the reasons of the formation of supersaturated solid solutions in immiscible systems with positive enthalpy of mixing. HREM observations carried out with the thermally decomposed Fe60Cu40 solid solution show that the Nishiyama (N-W) or Kurdyumov-Sachs (K-S) orientation relationships exist between alpha-Fe and Cu. Energy dispersive X-ray spectra (EDXS) results show that the Cu content in these alpha-Fe grains reaches as high as 9.5 at.% even after heating to 1,400 degrees C, which is even higher than the maximum solubility of Cu in gamma-Fe at 1,094 degrees C.

  2. Structural evolution of ball-milled permalloy

    NASA Astrophysics Data System (ADS)

    Brzózka, K.; Olekšáková, D.; Kollár, P.; Szumiata, T.; Górka, B.; Gawroński, M.

    Two series of Fe19.8sNi80.2 samples obtained by ball milling and differing in the form of starting material were investigated by Mössbauer spectroscopy. In the case of milled elemental powder, strong structural evolution was stated: both α and Γ phases arise and a small amount of pure iron is present as well. The annealing of as-milled powder at 490°C causes faster forming of Γ-(Ni-Fe) phase. Only slight changes in atomic order were stated in the series of milled polycrystalline ribbon.

  3. Structural evolution of ball-milled permalloy

    NASA Astrophysics Data System (ADS)

    Brzózka, K.; Olekšáková, D.; Kollár, P.; Szumiata, T.; Górka, B.; Gawroński, M.

    2006-02-01

    Two series of Fe19.8Ni80.2 samples obtained by ball milling and differing in the form of starting material were investigated by Mössbauer spectroscopy. In the case of milled elemental powder, strong structural evolution was stated: both α and γ phases arise and a small amount of pure iron is present as well. The annealing of as-milled powder at 490°C causes faster forming of γ-(Ni Fe) phase. Only slight changes in atomic order were stated in the series of milled polycrystalline ribbon.

  4. Mechanically Induced Graphite-Nanodiamonds-Phase Transformations During High-Energy Ball Milling

    NASA Astrophysics Data System (ADS)

    El-Eskandarany, M. Sherif

    2017-05-01

    Due to their unusual mechanical, chemical, physical, optical, and biological properties, nearly spherical-like nanodiamonds have received much attention as desirable advanced nanomaterials for use in a wide spectrum of applications. Although, nanodiamonds can be successfully synthesized by several approaches, applications of high temperature and/or high pressure may restrict the real applications of such strategic nanomaterials. Distinct from the current preparation approaches used for nanodiamonds preparation, here we show a new process for preparing ultrafine nanodiamonds (3-5 nm) embedded in a homogeneous amorphous-carbon matrix. Our process started from high-energy ball milling of commercial graphite powders at ambient temperature under normal atmospheric helium gas pressure. The results have demonstrated graphite-single wall carbon nanotubes-amorphous-carbon-nanodiamonds phase transformations carried out through three subsequent stages of ball milling. Based on XRD and RAMAN analyses, the percentage of nanodiamond phase + C60 (crystalline phase) produced by ball milling was approximately 81%, while the amorphous phase amount was 19%. The pressure generated on the powder together the with temperature increase upon the ball-powder-ball collision is responsible for the phase transformations occurring in graphite powders.

  5. Microstructural Evolution of Dy₂O₃-TiO₂ Powder Mixtures during Ball Milling and Post-Milled Annealing.

    PubMed

    Huang, Jinhua; Ran, Guang; Lin, Jianxin; Shen, Qiang; Lei, Penghui; Wang, Xina; Li, Ning

    2016-12-28

    The microstructural evolution of Dy₂O₃-TiO₂ powder mixtures during ball milling and post-milled annealing was investigated using XRD, SEM, TEM, and DSC. At high ball-milling rotation speeds, the mixtures were fined, homogenized, nanocrystallized, and later completely amorphized, and the transformation of Dy₂O₃ from the cubic to the monoclinic crystal structure was observed. The amorphous transformation resulted from monoclinic Dy₂O₃, not from cubic Dy₂O₃. However, at low ball-milling rotation speeds, the mixtures were only fined and homogenized. An intermediate phase with a similar crystal structure to that of cubic Dy₂TiO₅ was detected in the amorphous mixtures annealed from 800 to 1000 °C, which was a metastable phase that transformed to orthorhombic Dy₂TiO₅ when the annealing temperature was above 1050 °C. However, at the same annealing temperatures, pyrochlore Dy₂Ti₂O₇ initially formed and subsequently reacted with the remaining Dy₂O₃ to form orthorhombic Dy₂TiO₅ in the homogenous mixtures. The evolutionary mechanism of powder mixtures during ball milling and subsequent annealing was analyzed.

  6. Microstructure and martensitic transformation in Si-coated TiNi powders prepared by ball milling

    SciTech Connect

    Kim, Jae-hyun; Cho, Gyu-bong; Im, Yeon-min; Chun, Byong-sun; Kim, Yeon-wook; Nam, Tae-hyun

    2013-12-15

    Graphical abstract: - Highlights: • Amorphous Si-coated TiNi powders were prepared successfully by ball milling. • Ti{sub 4}Ni{sub 4}Si{sub 7} was formed at the interface between Si and TiNi after annealing. • Si-coated Ti–Ni powders displayed the R phase after annealing. - Abstract: Si was coated on the surface of Ti–49Ni (at%) alloy powders by ball milling in order to improve the electrochemical properties of the Si electrodes of secondary Li ion batteries and then the microstructure and martensitic transformation behavior were investigated by means of scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and differential scanning calorimetry (DSC). Ti–Ni powders coated with Si were fabricated successfully by ball milling. As-milled powders consisted of highly deformed Ti–Ni powders with the B2 phase and amorphous Si layers. The thickness of the Si layer coated on the surface of the Ti–Ni powders increased from 3–5 μm to 10–15 μm by extending the milling time from 3 h to 48 h. However, severe contamination from the grinding media, ZrO{sub 2} occurred when the ball milling time was as long as 48 h. By heating as-milled powders to various temperatures in the range of 673–873 K, the highly deformed Ti–Ni powders were recovered and Ti{sub 4}Ni{sub 4}Si{sub 7} was formed. Two-stage B2–R–B19′ transformation occurred when as-milled Si-coated Ti–49Ni alloy powders were heated to temperatures below 873 K, above this temperature one-stage B2–B19′ transformation occurred.

  7. Following mechanical activation of salbutamol sulphate during ball-milling with isothermal calorimetry.

    PubMed

    Gaisford, Simon; Dennison, Mansa; Tawfik, Mahmoud; Jones, Matthew D

    2010-06-30

    Formulation of actives for pulmonary delivery with dry powder inhaler devices frequently requires a particle size reduction step. The high-energy forces imparted to a material during milling, as well as reducing particle size, can cause a significant change in physicochemical properties, in particular mechanical activation of the surface (manifested as generation of amorphous regions) which can affect formulated product performance. It is not clear whether particle size reduction occurs prior to, or concomitantly with, generation of amorphous content. In this study the formation of amorphous content with time in crystalline salbutamol sulphate was quantified with isothermal gas perfusion calorimetry as the sample was ball-milled. The data showed that the most particle size reduction occurred initially (d(0.5) dropping from 12.83+/-0.4 to 4.2+/-0.4 within 5 min). During this time period, no detectable amorphous content was observed. Between 5 and 15 min milling time the particle size distribution remained relatively constant but the amorphous content increased non-linearly with time. After 20 min milling time the particle size increased slightly. The data suggest that particle size reduction occurs initially upon application of a force to the crystal. Once maximum particle size reduction has occurred the crystal absorbs the force being applied and the crystal lattice becomes disordered. After extended milling the conditions in the ball mill (heat and/or humidity) may cause crystallisation of some of the amorphous material resulting in particle-particle fusion. It would appear that the ball-milling process could be optimised to achieve the desired particle size distribution but without any loss of crystalline structure.

  8. 7. Ball mill area and second level entry with overhead ...

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

    7. Ball mill area and second level entry with overhead crane in background - Bureau of Mines Boulder City Experimental Station, Ore Dressing Pilot Plant, Date Street north of U.S. Highway 93, Boulder City, Clark County, NV

  9. DETAIL OF CYCLONE CLASSIFIER, WITH MARCY NO. 86 BALL MILL ...

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

    DETAIL OF CYCLONE CLASSIFIER, WITH MARCY NO. 86 BALL MILL BELOW AND BEHIND IT. STRAIGHT HORIZONTAL PIPE IS SLIME FEED FROM ROD MILL. PIPE OUT TOP OF CYCLONE AND CURVING AT LOWER RIGHT CARRIED FINELY GROUND SLIME TO FLOTATION CONDITIONER TANK. PIPE NOT VISIBLE OUT BOTTOM OF CYCLONE CONVEYED COARSER SLIME TO BALL MILL. - Shenandoah-Dives Mill, 135 County Road 2, Silverton, San Juan County, CO

  10. Degradation characteristics of dioxin in the fly ash by washing and ball-milling treatment.

    PubMed

    Li, Baohua; Deng, Zhiyi; Wang, Wenxiang; Fang, Hongsheng; Zhou, Haibiao; Deng, Fangxin; Huang, Ling; Li, Huiying

    2017-10-05

    In this study, samples were taken from different types of municipal waste incineration plants in the Pearl River Delta, China. Analyzing the distributive characters of elements and dioxin congeners in fly ash, the method of washing-ball milling was utilized to remove chloride and degrade dioxin in fly ash. The results showed that more than 90% of particles were in the range of 1∼50μm and most of dioxin and metals existed in 0.030∼0.075mm of particles. K, Na, Cl and Br in fly ash could be removed by washing efficiently, however dioxin and other metals remained in the solid phase. Washing and Fe/Ni-SiO2 ball-milling method seemed to be the best choice as the dioxin removal rate could reach up to 93.20%. Dioxin could be degraded to low toxic compounds and heterochorides with Fe/Ni as dechlorinating agent. In the process, PCDFs were partly transformed to PCDDs, while too long time of ball-milling was not benefited for dioxin removing. In addition, the phases of calcium such as Ca(OH)2, CaCO3 and CaSO4 in fly ash could transform from crystal to amorphous. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. Powder properties of hydrogenated ball-milled graphite

    SciTech Connect

    Zhang, Y.; Wedderburn, J.; Harris, R.; Book, D.

    2014-12-15

    Ball milling is an effective way of producing defective and nanostructured graphite. In this work, the hydrogen storage properties of graphite, ball-milled in a tungsten carbide milling pot under 3 bar hydrogen for various times (0–40 h), were investigated by TGA-Mass Spectrometry, XRD, SEM and laser diffraction particle size analysis. For the conditions used in this study, 10 h is the optimum milling time resulting in desorption of 5.5 wt% hydrogen upon heating under argon to 990 °C. After milling for 40 h, the graphite became significantly more disordered, and the amount of desorbed hydrogen decreased. After milling up to 10 h, the BET surface area increased while particle size decreased; however, there is no apparent correlation between these parameters, and the hydrogen storage properties of the hydrogenated ball-milled graphite.

  12. The effect of ball milling grinding pathways on the bulk and reactivity properties of calcium phosphate cements.

    PubMed

    Lopez-Heredia, M A; Bohner, M; Zhou, W; Winnubst, A J A; Wolke, J G C; Jansen, J A

    2011-07-01

    Calcium phosphate cements (CPCs) are significant alternatives to autologous bone grafting. CPCs can be composed of biphasic or multiphase calcium phosphate (CaP) compounds. A common way to process CPCs is by ball milling. Ball milling can be used for grinding or mechanosynthesis. The aim of this study was to determine the effect of well-defined ball milling grinding parameters, applied via different milling pathways, on the properties of CPCs. Starting CaP compounds used included α-tricalcium phosphate, dicalcium phosphate anhydrous and precipitated hydroxyapatite. Scanning electron microscopy showed changes in the powder morphology, which were related to the behavior of the starting CaP materials. Specific surface area (SSA) and particle size (PS) measurements exposed the effect of ball milling on the CaP compounds and CPC powders. X-ray diffraction revealed no effect of ball milling pathways or milling time on the composition of CPCs or the starting materials, but affected their crystallographic properties. No contamination of the milling media or transformation into an amorphous calcium phosphate compound was found. The milling pathways affected setting and cohesion. Fourier transform infrared spectroscopy (FTIR) revealed differences on the CPC v₄-PO₄³⁻ bands according to the interaction, created between the CaP compounds by the milling pathways. FTIR confirmed that the milling pathways changed the crystallographic properties. This study demonstrates that the pathways used for milling grinding modify the PS, SSA, and crystallographic properties of the powders, without affecting their composition. These modifications affected the bulk and reactivity properties of the CPCs by creating different setting and cohesion behaviors.

  13. Magnetic properties of ball milled Fe-40Al at.% alloys

    SciTech Connect

    Amils, X.; Nogues, J.; Surinach, S.; Baro, M.D.; Munoz, J.S.

    1998-07-01

    A direct correlation between the lattice parameter and the saturation magnetization, during the disordering (ball milling) and posterior reordering (annealing) processes, has been found in Fe-40Al At.% compounds. These results indicate that the paramagnetic-ferromagnetic-paramagnetic transitions induced by ball milling and subsequent annealing could be related to the changes in volume, and not only to nearest neighbors effects as is commonly assumed. Moreover, these alloys have been found to become spin glass at low temperatures, independently of their structural state (ordered or disordered).

  14. Planetary ball milling and supercritical fluid technology as a way to enhance dissolution of bicalutamide.

    PubMed

    Szafraniec, Joanna; Antosik, Agata; Knapik-Kowalczuk, Justyna; Kurek, Mateusz; Syrek, Karolina; Chmiel, Krzysztof; Paluch, Marian; Jachowicz, Renata

    2017-03-29

    Dissolution of bicalutamide processed with polyvinylpyrrolidone by either supercritical carbon dioxide or ball milling has been investigated. Various compositions as well as process parameters were used to obtain binary systems of the drug with the carrier. Thermal analysis and powder X-ray diffractometry confirmed amorphization of bicalutamide mechanically activated by ball milling and the decrease in crystallinity of the supercritical carbon dioxide-treated drug. Both methods led to reduction of particles size what was confirmed by scanning electron microscopy and laser diffraction measurements. Moreover, the effect of micronisation was found to depend on the parameters of applied process. Fourier transform infrared spectroscopy revealed the appearance of intermolecular interactions between drug and carrier molecules that play an important role in the stabilization of amorphous form of the active compound. Changes in crystal structure combined with reduced size of particles of bicalutamide dispersed within polymer matrix were found to improve dissolution of bicalutamide by 4 to 10-fold in comparison to untreated drug. It is of particular importance as poor dissolution profiles are considered to be the major limitation in bioavailability of the drug. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. High-Energy Ball Milling as Green Process To Vitrify Tadalafil and Improve Bioavailability.

    PubMed

    Krupa, Anna; Descamps, Marc; Willart, Jean-François; Strach, Beata; Wyska, Elżbieta; Jachowicz, Renata; Danède, Florence

    2016-11-07

    In this study, the suitability of high-energy ball milling was investigated with the aim to vitrify tadalafil (TD) and improve its bioavailability. To achieve this goal, pure TD as well as binary mixtures composed of the drug and Soluplus (SL) were coprocessed by high-energy ball milling. Modulated differential scanning calorimetry (MDSC) and X-ray powder diffraction (XRD) demonstrated that after such coprocessing, the crystalline form of TD was transformed into an amorphous form. The presence of a single glass transition (Tg) for all the comilled formulations indicated that TD was dispersed into SL at the molecular level, forming amorphous molecular alloys, regardless of the drug concentration. The high values of Tg determined for amorphous formulations, ranging from 70 to 147 °C, foreshow their high stability during storage at room temperature, which was verified by XRD and MDSC studies. The stabilizing effect of SL on the amorphous form of TD in comilled formulations was confirmed. Dissolution tests showed immediate drug release with sustained supersaturation in either simulated gastric fluid of pH 1.2 or in phosphate buffer of pH 7.2. The beneficial effect of both amorphization and coamorphization on the bioavailability of TD was found. In comparison to aqueous suspension, the relative bioavailability of TD was only 11% for its crystalline form and 53% for the crystalline physical mixture, whereas the bioavailability of milled amorphous TD and the comilled solid dispersion was 128% and 289%, respectively. Thus, the results provide evidence that not only the presence of polymeric surfactant but also the vitrification of TD is necessary to improve bioavailability.

  16. High-Energy Ball-Milling of Alloys and Compounds

    NASA Astrophysics Data System (ADS)

    Le Caër, G.; Delcroix, P.; Bégin-Colin, S.; Ziller, T.

    2002-06-01

    After outlining some characteristics of high-energy ball-milling, we discuss selected examples of phase transformation and of alloy synthesis which focus on deviations from archetypal behaviours and throw light on the milling mechanisms. Some contributions of Mössbauer spectrometry to the characterization of ground materials are described.

  17. 6. FF coal pulverizer (ball mill inside). GG building in ...

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

    6. FF coal pulverizer (ball mill inside). GG building in background did preliminary crushing; pulverizer to left, coal conveyor and air cleaning towers to right; conveyor on left brought crushed coal to FF. Looking north/northeast - Rouge Steel Company, 3001 Miller Road, Dearborn, MI

  18. Preparation of Nb3Al by high-energy ball milling and superconductivity

    NASA Astrophysics Data System (ADS)

    Chen, Yongliang; Liu, Zhao; Li, Pingyuan; Zhang, Xiaolan; Yang, Suhua; Yang, Dawei; Du, Lupeng; Cui, Yajing; Pan, Xifeng; Yan, Guo; Zhao, Yong

    2014-05-01

    The A15 phase superconductor Nb3Al has been considered as an alternative to Nb3Sn for high field and large scale applications. However, to prepare a stoichiometric Nb3Al with fine grain structures is very difficult. High-energy ball milling is a solid state powder processing technique and is a very useful for preparing Nb-Al alloys (Nb3Al). The effects of ball milling time and annealing temperature on the formation of Nb3Al superconducting phase have been studied. Pure Nb and Al powders with stoichiometric ratio of Nb3Al were mixed and milled, and the charging and milling were performed in an inert atmosphere. Phase formation and structural evolution during high-energy ball milling have been examined by X-ray diffraction. Al disappeared and Nb peaks broadened after about one hour of milling. With increasing milling time, the peaks of Nb became considerably broader and intensities decreased, the Nb-Al solid solution phase was extensive when milled about 3 hours. In order to obtain Nb3Al superconducting phase, a subsequent anneal was required. We have annealed the as-milled powders at 800-900°C for different times to prepared Nb3Al superconducting alloy. The results indicated that Nb3Al with small amount of impurity phase can be obtained on annealing the Nb-Al solid solution phase and the superconducting transition temperature was about 15K, but it is difficult to obtain a homogeneous Nb3Al phase by annealing the amorphous powder.

  19. Microstructural Evolution of Dy2O3-TiO2 Powder Mixtures during Ball Milling and Post-Milled Annealing

    PubMed Central

    Huang, Jinhua; Ran, Guang; Lin, Jianxin; Shen, Qiang; Lei, Penghui; Wang, Xina; Li, Ning

    2016-01-01

    The microstructural evolution of Dy2O3-TiO2 powder mixtures during ball milling and post-milled annealing was investigated using XRD, SEM, TEM, and DSC. At high ball-milling rotation speeds, the mixtures were fined, homogenized, nanocrystallized, and later completely amorphized, and the transformation of Dy2O3 from the cubic to the monoclinic crystal structure was observed. The amorphous transformation resulted from monoclinic Dy2O3, not from cubic Dy2O3. However, at low ball-milling rotation speeds, the mixtures were only fined and homogenized. An intermediate phase with a similar crystal structure to that of cubic Dy2TiO5 was detected in the amorphous mixtures annealed from 800 to 1000 °C, which was a metastable phase that transformed to orthorhombic Dy2TiO5 when the annealing temperature was above 1050 °C. However, at the same annealing temperatures, pyrochlore Dy2Ti2O7 initially formed and subsequently reacted with the remaining Dy2O3 to form orthorhombic Dy2TiO5 in the homogenous mixtures. The evolutionary mechanism of powder mixtures during ball milling and subsequent annealing was analyzed. PMID:28772375

  20. Modeling High-Energy Ball Milling in the Alumina-Yttria System

    NASA Astrophysics Data System (ADS)

    Alkebro, J.; Bégin-Colin, S.; Mocellin, A.; Warren, R.

    2002-02-01

    Experimental results from high-energy ball milling of alumina-yttria powder mixtures have been analyzed with models collected from the literature. Depending on the milling conditions, either there is formation of an intermediate phase in the alumina-yttria system (yttrium aluminum perovskite, YAP), or the sample becomes mostly amorphous. Variations due to milling tool material can be accounted for by local models based on the Hertzian theory of elastic bodies, but the effects of changing mills are poorly accounted for by published models. Therefore, the concept of an impact frequency distribution over the energy spectrum is introduced as a tool for studying the characteristics of the mills. The pressure on the powder trapped between two colliding bodies has been found to be the factor deciding the outcome of the process. The threshold behavior of the system yields an amorphous structure for low pressures, and formation of YAP when impact pressures exceed the threshold value.

  1. Phase evolution in carbide dispersion strengthened nanostructured copper composite by high energy ball milling

    NASA Astrophysics Data System (ADS)

    Hussain, Zuhailawati; Nur Hawadah, M. S.

    2012-09-01

    In this study, high-energy ball milling was applied to synthesis in situ nanostructured copper based composite reinforced with metal carbides. Cu, M (M=W or Ti) and graphite powder mixture were mechanically alloyed for various milling time in a planetary ball mill with composition of Cu-20vol%WC and Cu-20vol%TiC. Then the as-milled powder were compacted at 200 to 400 MPa and sintered in a vacuum furnace at 900°C. The results of X-ray diffraction, scanning electron microscopy and energy dispersive spectroscopy analysis showed that formation of tungsten carbides (W2C and WC phases) was observed after sintering of Cu-W-C mixture while TiC precipitated in as-milled powder of Cu-Ti-C composite after 5 h and become amorphous with longer milling. Mechanism of MA explained the cold welding and fracturing event during milling. Cu-W-C system shows fracturing event is more dominant at early stage of milling and W particle still existed after milling up to 60 h. While in Cu-Ti-C system, cold welding is more dominant and all Ti particles dissolved into Cu matrix.

  2. Phase evolution in carbide dispersion strengthened nanostructured copper composite by high energy ball milling

    SciTech Connect

    Hussain, Zuhailawati; Nur Hawadah, M. S.

    2012-09-06

    In this study, high-energy ball milling was applied to synthesis in situ nanostructured copper based composite reinforced with metal carbides. Cu, M (M=W or Ti) and graphite powder mixture were mechanically alloyed for various milling time in a planetary ball mill with composition of Cu-20vol%WC and Cu-20vol%TiC. Then the as-milled powder were compacted at 200 to 400 MPa and sintered in a vacuum furnace at 900 Degree-Sign C. The results of X-ray diffraction, scanning electron microscopy and energy dispersive spectroscopy analysis showed that formation of tungsten carbides (W{sub 2}C and WC phases) was observed after sintering of Cu-W-C mixture while TiC precipitated in as-milled powder of Cu-Ti-C composite after 5 h and become amorphous with longer milling. Mechanism of MA explained the cold welding and fracturing event during milling. Cu-W-C system shows fracturing event is more dominant at early stage of milling and W particle still existed after milling up to 60 h. While in Cu-Ti-C system, cold welding is more dominant and all Ti particles dissolved into Cu matrix.

  3. Synthesis of Randomly Substituted Anionic Cyclodextrins in Ball Milling.

    PubMed

    Jicsinszky, László; Caporaso, Marina; Calcio Gaudino, Emanuela; Giovannoli, Cristina; Cravotto, Giancarlo

    2017-03-19

    A number of influencing factors mean that the random substitution of cyclodextrins (CD) in solution is difficult to reproduce. Reaction assembly in mechanochemistry reduces the number of these factors. However, lack of water can improve the reaction outcomes by minimizing the reagent's hydrolysis. High-energy ball milling is an efficient, green and simple method for one-step reactions and usually reduces degradation and byproduct formation. Anionic CD derivatives have successfully been synthesized in the solid state, using a planetary ball mill. Comparison with solution reactions, the solvent-free conditions strongly reduced the reagent hydrolysis and resulted in products of higher degree of substitution (DS) with more homogeneous DS distribution. The synthesis of anionic CD derivatives can be effectively performed under mechanochemical activation without significant changes to the substitution pattern but the DS distributions were considerably different from the products of solution syntheses.

  4. Ultrasonically assisted synthesis of lead oxide nanoflowers using ball milling

    NASA Astrophysics Data System (ADS)

    Bangi, Uzma K. H.; Park, Hyung-Ho; Han, Wooje; Prakshale, Vipul M.; Deshmukh, Lalasaheb P.

    2017-05-01

    The experimental results on the ultrasonically assisted synthesis of lead oxide nanoflowers using ball milling have been reported in the present work. Lead oxide nanoflowers were prepared employing mixed ligands by subjecting the formed precipitate to ultrasonication and grinding/ball milling. The effect of ball milling as well as fine grinding in agate mortar on the microstructure and surface morphology of the lead oxide was studied. The characteristics of synthesized PbO were studied using X-ray diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy and field emission scanning electron microscopy techniques. XRD results demonstrated the tetragonal phase of PbO with crystallite size of around 25 nm and strain of 3.6 × 10-3 calculated from Williamson-Hall plot. FESEM images manifested the formation of nanodiscs and nanoflowers with a diameter of around 300 nm and thickness of 50 nm. XPS spectra revealed the formation of PbO with photoelectron peak of Pb 4f and O 1 s lied at 137.68 and 529.96 eV. Moreover, FTIR spectrum exhibited Pb-O bond peak in the range of 400-530 cm-1.

  5. Ball-milled sulfur-doped graphene materials contain metallic impurities originating from ball-milling apparatus: their influence on the catalytic properties.

    PubMed

    Chua, Chun Kiang; Sofer, Zdeněk; Khezri, Bahareh; Webster, Richard D; Pumera, Martin

    2016-07-21

    Graphene materials have found applications in a wide range of devices over the past decade. In order to meet the demand for graphene materials, various synthesis methods are constantly being improved or invented. Ball-milling of graphite to obtain graphene materials is one of the many versatile methods to easily obtain bulk quantities. In this work, we show that the graphene materials produced by ball-milling are spontaneously contaminated with metallic impurities originating from the grinding bowls and balls. Ball-milled sulfur-doped graphene materials obtained from two types of ball-milling apparatus, specifically made up of stainless steel and zirconium dioxide, were investigated. Zirconium dioxide-based ball-milled sulfur-doped graphene materials contain a drastically lower amount of metallic impurities than stainless steel-based ball-milled sulfur-doped graphene materials. The presence of metallic impurities is demonstrated by their catalytic effects toward the electrochemical catalysis of hydrazine and cumene hydroperoxide. The general impression toward ball-milling of graphite as a versatile method for the bulk production of 'metal-free' graphene materials without the need for post-processing and the selection of ball-milling tools should be cautioned. These findings would have wide-reaching implications for graphene research.

  6. Synthesis and characterization of Mg-based amorphous alloys and their use for decolorization of Azo dyes

    NASA Astrophysics Data System (ADS)

    Iqbal, M.; Wang, W. H.

    2014-06-01

    Mg-based alloys are light weight and have wide range of applications in the automotive industry. These alloys are widely used because of their very attractive physical and mechanical properties and corrosion resistance. The properties and applications can be further improved by changing the nature of materials from crystalline to amorphous. In this study, melt spun ribbons (MSRs) of Mg70Zn25Ca5 Mg68Zn27Ca5 alloys were prepared by melt spinning technique by using 3-4N pure metals. Characterization of the samples was done by X-ray diffraction (XRD), differential scanning calorimetry (DSC) and energy dispersive x-ray analyzer (EDAX). Microstructural investigations were conducted by using scanning electron microscopy (SEM), atomic force microscopy (AFM) as well as optical and stereo scan microscopy techniques. DSC results showed multistage crystallization. Activation energy was found to be 225 kJ/mol by Kissinger method indicating good thermal stability against crystallization. XRD, DSC, SEM and EDS (energy dispersive spectroscopy) results are agreed very well. In order to study decolorization, the MSRs of Mg70Zn25Ca5 Mg68Zn27Ca5 alloys were treated repeatedly with various azo dyes at room temperature. In order to compare the results, MSRs of amorphous Zr- and Ni-based metallic glasses were also treated. Reaction of MSRs with azo dyes results in their decolorization in a few hours. Decolorization of azo dyes takes place by introducing amorphous MSRs which results in breaking the -N=N- bonds that exist in dye contents. It is concluded that Mg-based alloys are useful for paint and dye industries and will be beneficial to control water pollution. Comparison of results showed that Mg-based alloys are more efficient than Zr- and Ni-based amorphous alloys for decolorization of azo dyes.

  7. Influence of ball milling on atomic structure and magnetic properties of Co{sub 40}Fe{sub 22}Ta{sub 8}B{sub 30} glassy alloy

    SciTech Connect

    Taghvaei, Amir Hossein; Stoica, Mihai; Bednarčik, Jozef; Kaban, Ivan; Shahabi, Hamed Shakur; Khoshkhoo, Mohsen Samadi; Janghorban, Kamal; Eckert, Jürgen

    2014-06-01

    The influence of ball milling on the atomic structure and magnetic properties of the Co{sub 40}Fe{sub 22}Ta{sub 8}B{sub 30} metallic glass with a high thermal stability and excellent soft magnetic properties has been investigated. After 14 h of milling, the obtained powders were found to consist mainly of an amorphous phase and a small fraction of the (Co,Fe){sub 21}Ta{sub 2}B{sub 6} nanocrystals. The changes in the reduced pair correlation functions suggest noticeable changes in the atomic structure of the amorphous upon ball milling. Furthermore, it has been shown that milling is accompanied by introduction of compressive and dilatational sites in the glassy phase and increasing the fluctuation of the atomic-level hydrostatic stress without affecting the coordination number of the nearest neighbors. Ball milling has decreased the thermal stability and significantly affected the magnetic properties through increasing the saturation magnetization, Curie temperature of the amorphous phase and coercivity. - Highlights: • Ball milling affected the atomic structure of Co{sub 40}Fe{sub 22}Ta{sub 8}B{sub 30} metallic glass. • Mechanically-induced crystallization started after 4 h milling. • Milling increased the fluctuation of the atomic-level hydrostatic stress in glass. • Ball milling influenced the thermal stability and magnetic properties.

  8. 130-fold enhancement of TiO2 photocatalytic activities by ball milling

    NASA Astrophysics Data System (ADS)

    Saitow, Ken-ichi; Wakamiya, Tomoji

    2013-07-01

    Submicrometer TiO2 particles were prepared by changing the mechanochemical parameters in planetary ball milling. The TiO2 particles before and after milling were characterized by five experimental methods. The photocatalytic activities of the TiO2 particles were evaluated by the photoreduction of an aqueous solution of methylene blue. The activity of milled TiO2 was 136 times that of TiO2 (anatase) before milling and 62 times that of commercial available TiO2 photocatalyst (P25). In addition to the reduction in particle size and increase in specific surface area due to milling, the disorder TiO2, involving amorphous and srilankite phases, significantly increased the catalytic performance.

  9. Iron nanoparticles produced by high-energy ball milling

    NASA Astrophysics Data System (ADS)

    Muñoz, Jorge E.; Cervantes, Janeth; Esparza, Rodrigo; Rosas, Gerardo

    2007-10-01

    In this investigation, the chemical and structural characteristics of Fe nanoparticles synthesized by high-energy ball milling have been explored. After the milling process the nanoparticles were collected using a magnetic field. The structure, morphology and composition of the powders were obtained using high-resolution electron microscopy. HREM images confirmed the nanoparticles' presence with approximately 2-4 nm in size. It was found that using this method allowed the formation of nanoparticles in a smaller size range than other synthesis methods. Also, it was confirmed by HREM images that the obtained nanoparticles were mainly of the fcc nature and some of them of the MTP type.

  10. Modeling Comminution Processes in Ball Mills as a Canonical Ensemble

    NASA Astrophysics Data System (ADS)

    Sunnardianto, G. K.; Muhandis, .; Diana, F. N.; Handoko, L. T.

    2011-02-01

    A new approach to describe comminution processes in general ball mills as a macroscopic canonical ensemble is proposed. Using hamiltonian method, the model is able to take simultaneously into account the internal dynamics from mechanical motions inside the vial and external effects like electromagnetic and gravitational forces. Relevant physical observables are extracted using statistical mechanics approach through partition function at finite temperature. The method enables numerical calculation using Monte Carlo technique to obtain, for instance particle number evolution in term of system temperature. It is argued that the method is experimentally more verifiable than the conventional approaches based on geometrical displacements. An example of simulation for typical spex mill is also given.

  11. Effects of ball-milling on lithium insertion into multi-walled carbon nanotubes synthesized by thermal chemical vapour deposition

    NASA Astrophysics Data System (ADS)

    Eom, JiYong; Kim, DongYung; Kwon, HyukSang

    The effects of ball-milling on Li insertion into multi-walled carbon nanotubes (MWNTs) are presented. The MWNTs are synthesized on supported catalysts by thermal chemical vapour deposition, purified, and mechanically ball-milled by the high energy ball-milling. The purified MWNTs and the ball-milled MWNTs were electrochemically inserted with Li. Structural and chemical modifications in the ball-milled MWNTs change the insertion-extraction properties of Li ions into/from the ball-milled MWNTs. The reversible capacity (C rev) increases with increasing ball-milling time, namely, from 351 mAh g -1 (Li 0.9C 6) for the purified MWNTs to 641 mAh g -1 (Li 1.7C 6) for the ball-milled MWNTs. The undesirable irreversible capacity (C irr) decreases continuously with increase in the ball-milling time, namely, from 1012 mAh g -1 (Li 2.7C 6) for the purified MWNTs to 518 mAh g -1 (Li 1.4C 6) for the ball-milled MWNTs. The decrease in C irr of the ball-milled samples results in an increase in the coulombic efficiency from 25% for the purified samples to 50% for the ball-milled samples. In addition, the ball-milled samples maintain a more stable capacity than the purified samples during charge-discharge cycling.

  12. Edge-carboxylated graphene nanosheets via ball milling

    PubMed Central

    Jeon, In-Yup; Shin, Yeon-Ran; Sohn, Gyung-Joo; Choi, Hyun-Jung; Bae, Seo-Yoon; Mahmood, Javeed; Jung, Sun-Min; Seo, Jeong-Min; Kim, Min-Jung; Wook Chang, Dong; Dai, Liming; Baek, Jong-Beom

    2012-01-01

    Low-cost, high-yield production of graphene nanosheets (GNs) is essential for practical applications. We have achieved high yield of edge-selectively carboxylated graphite (ECG) by a simple ball milling of pristine graphite in the presence of dry ice. The resultant ECG is highly dispersable in various solvents to self-exfoliate into single- and few-layer (≤ 5 layers) GNs. These stable ECG (or GN) dispersions have been used for solution processing, coupled with thermal decarboxylation, to produce large-area GN films for many potential applications ranging from electronic materials to chemical catalysts. The electrical conductivity of a thermally decarboxylated ECG film was found to be as high as 1214 S/cm, which is superior to its GO counterparts. Ball milling can thus provide simple, but efficient and versatile, and eco-friendly (CO2-capturing) approaches to low-cost mass production of high-quality GNs for applications where GOs have been exploited and beyond. PMID:22454492

  13. Thermally Driven and Ball-Milled Hematite to Magnetite Transformation

    NASA Astrophysics Data System (ADS)

    Betancur, J. D.; Restrepo, J.; Palacio, C. A.; Morales, A. L.; Mazo-Zuluaga, J.; Fernández, J. J.; Pérez, O.; Valderruten, J. F.; Bohórquez, A.

    2003-06-01

    In this work, a study on the dynamics of transformation from hematite (α-Fe2O3) to magnetite (Fe3O4) by following two solid-state reaction methods is carried out. One of the procedures consists of a thermal treatment under a 20% H2 and 80% N2 atmosphere at 375°C, whereas the second method involves a planetary ball mill to induce the transformation. The phases evolution as a function of the thermal treatment time ranging from 0 up to 25 min every 2.5 min, and from 0 up to 6 hours every hour in the case of the milling method, was followed by using room-temperature Mössbauer spectroscopy and X-ray diffraction analysis. Results evidence a well-behaved structural transformation for which highly stoichiometric Fe3O4 as a single phase was obtained for treatment times above 12.5 min in the case of the thermally treated samples. Differently from this a less stoichiometric magnetite characterized by a distribution of hyperfine fields for milling times above 3 hours in the case of the ball milled samples was obtained. For reaction times below 12.5 min, two interpretation models based on the presence of an anion-deficient magnetite Fe3O4-δ and the presence of maghemite accounting for the intermediate states during the thermal transformation are also presented and discussed.

  14. Comminution-amorphisation relationships during ball milling of lactose at different milling conditions.

    PubMed

    Pazesh, Samaneh; Gråsjö, Johan; Berggren, Jonas; Alderborn, Göran

    2017-08-07

    The purpose of the study was to investigate the relationship between comminution and amorphisation of α-lactose monohydrate particles during ball milling under different milling conditions, including ball-to-powder mass ratio, milling time and ball diameter. The results revealed that at a constant ball filling ratio, ball-to-powder mass ratio of 25:1 resulted in the lowest minimum particle diameter of ∼5μm and the highest degree of apparent amorphous content of 82%. The rate of comminution was high during early stage of milling whereas the degree of apparent amorphous content increased gradually at a slow rate. An increased ball-to-powder mass ratio during milling increased both the rate of comminution and the rate of amorphisation. Using a given ball-to-powder mass ratio, the ball diameter affected the degree of apparent amorphous content of the particles while the particle diameter remained unchanged. The relationship between comminution and amorphisation could be described as consisting of two stages, i.e. comminution dominated and amorphisation dominated stage. It was proposed that the rate constant of comminution and amorphisation are controlled by stress energy distribution in the milling jar and the stress energy distribution is regulated by the ball motion pattern that can be affected by the process parameter used. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

  15. Regularity and mechanism of wheat straw properties change in ball milling process at cellular scale.

    PubMed

    Gao, Chongfeng; Xiao, Weihua; Ji, Guanya; Zhang, Yang; Cao, Yaoyao; Han, Lujia

    2017-10-01

    To investigate the change of structure and physicochemical properties of wheat straw in ball milling process at cellular scale, a series of wheat straws samples with different milling time were produced using an ultrafine vibration ball mill. A multitechnique approach was used to analyze the variation of wheat straw properties. The results showed that the characteristics of wheat straw powder displayed regular changes as a function of the milling time, i.e., the powder underwent the inversion of breakage to agglomerative regime during wheat straw ball milling process. The crystallinity index, bulk density and water retention capacity of wheat straw were exponential relation with ball milling time. Moreover, ball milling continually converted macromolecules of wheat straw cell wall into water-soluble substances resulting in the water extractives proportional to milling time. Copyright © 2017. Published by Elsevier Ltd.

  16. Characterization of oxide layers on amorphous Mg-based alloys by Auger electron spectroscopy with sputter depth profiling.

    PubMed

    Baunack, S; Subba Rao, R V; Wolff, U

    2003-04-01

    Amorphous ribbons of Mg-Y-TM-[Ag] (TM: Cu, Ni), prepared by melt spinning, were subjected to electrochemical investigations. Oxide layers formed anodically under potentiostatic control in different electrolytes were investigated by AES and sputter depth profiling. Problems and specific features of characterization of the composition of oxide layers and amorphous ternary or quaternary Mg-based alloys have been investigated. In the alloys the Mg(KL(23)L(23)) peak exhibits a different shape compared to that in the pure element. Analysis of the peak of elastically scattered electrons proved the absence of plasmon loss features, characteristic of pure Mg, in the alloy. A different loss feature emerges in Mg(KL(23)L(23)) and Cu(L(23)VV). The system Mg-Y-TM-[Ag] suffers preferential sputtering. Depletion of Mg and enrichment of TM and Y are found. This is attributed mainly to the preferential sputtering of Mg. Thickness and composition of the formed oxide layer depend on the electrochemical treatment. After removing the oxide by sputtering the concentration of the underlying alloy was found to be affected by the treatment.

  17. Modeling and Analysis of High-Energy Ball Milling Through Attritors

    NASA Astrophysics Data System (ADS)

    Zhao, Xuzhe; Shaw, Leon

    2017-09-01

    The effects of major processing parameters of attritor mills on ball milling efficiency ( i.e., minimum energy consumption with maximum milling progress) are investigated using discrete element modeling (DEM). The major processing parameters investigated include the size of balls, ball volume fraction inside the canister, ball milling velocity, and design of the impeller shaft of the attritor mill. Their effects are studied through examination of the output parameters including the average speed of balls, maximum speed of balls, and torque applied on the impeller shaft. The torque on the impeller shaft represents the energy consumption during ball milling, while the difference between the maximum and average speeds of balls scales with the compressive pressure during "mini-forging" of powder particles trapped between the colliding balls and thus scales with milling progress (particle deformation and size reduction). The simulation reveals that the ball milling velocity, ball volume fraction inside the canister, ball size, and impeller shaft design are all important parameters for energy-efficient ball milling. In particular, high ball milling velocities can lead to larger particle deformation and faster size reduction with minimum energy consumption. Further, ball sizes smaller than the gap that will not be hit by impellers directly are good for high-energy-efficient ball milling. Otherwise, energy consumption increases substantially.

  18. A comparison of cellulose nanocrystals and cellulose nanofibres extracted from bagasse using acid and ball milling methods

    NASA Astrophysics Data System (ADS)

    Rahimi Kord Sofla, M.; Brown, R. J.; Tsuzuki, T.; Rainey, T. J.

    2016-09-01

    This study compared the fundamental properties of cellulose nanocrystals (CNC) and cellulose nanofibrils (CNF) extracted from sugarcane bagasse. Conventional hydrolysis was used to extract CNC while ball milling was used to extract CNF. Images generated by scanning electron microscope and transmission electron microscope showed CNC was needle-like with relatively lower aspect ratio and CNF was rope-like in structure with higher aspect ratio. Fourier-transformed infrared spectra showed that the chemical composition of nanocellulose and extracted cellulose were identical and quite different from bagasse. Dynamic light scattering studies showed that CNC had uniform particle size distribution with a median size of 148 nm while CNF had a bimodal size distribution with median size 240 ± 12 nm and 10 μm. X-ray diffraction showed that the amorphous portion was removed during hydrolysis; this resulted in an increase in the crystalline portion of CNC compared to CNF. Thermal degradation of cellulose initiated at a much lower temperature, in the case of the nanocrystals while the CNF prepared by ball milling were not affected, indicating higher thermal stability.

  19. Investigation of the effect of intensive ball milling in a planetary ball mill on the thermal decomposition of cadmium carbonate and basic zinc carbonate

    NASA Astrophysics Data System (ADS)

    Ksiadot zek, K.; Wacke, S.; Górecki, T.; Górecki, Cz

    2007-08-01

    The kinetics of thermal decomposition of cadmium carbonate CdCO3 and basic zinc carbonate ZnCO3·nZn(OH)2 and the effect of intensive milling in a planetary ball mill on its parameters, have been investigated. The values of the reaction heat and of the activation energies of thermal decomposition have been determined for both the compounds. Investigations of the thermal decomposition of the products of ball milling of investigated compounds revealed a slight effect of milling conditions on the reaction temperature and heat consumed during the thermal decomposition of ZnCO3·nZn(OH)2. No effect of ball milling on the thermal decomposition of CdCO3 has been found.

  20. Processing of magnetically anisotropic MnBi particles by surfactant assisted ball milling

    NASA Astrophysics Data System (ADS)

    Kanari, K.; Sarafidis, C.; Gjoka, M.; Niarchos, D.; Kalogirou, O.

    2017-03-01

    MnBi particles are obtained from bulk MnBi using mechanochemical processing. The structure and magnetic properties of the MnBi particles are investigated by means of X-ray diffraction analysis, scanning electron microscopy and magnetometry. Surfactant assisted high energy ball milling results to the samples' degradation even after one hour of milling. In the case of surfactant assisted low energy ball milling the increase of ball milling duration decreases the average particle size while the particles seem to be more separated. The saturation magnetization (Ms) was found to decrease for large milling times beginning from 61 Am2/kg, while the coercivity (μ0Hc) increases with the increase of ball milling duration up to 35 min where it reaches 1.62 T and thereafter it decreases.

  1. Preferential Carbon Monoxide Oxidation over Copper-Based Catalysts under In Situ Ball Milling.

    PubMed

    Eckert, Rene; Felderhoff, Michael; Schüth, Ferdi

    2017-02-20

    In situ ball milling of solid catalysts is a promising yet almost unexplored concept for boosting catalytic performance. The continuous preferential oxidation of CO (CO-PROX) under in situ ball milling of Cu-based catalysts such as Cu/Cr2 O3 is presented. At temperatures as low as -40 °C, considerable activity and more than 95 % selectivity were achieved. A negative apparent activation energy was observed, which is attributed to the mechanically induced generation and subsequent thermal healing of short-lived surface defects. In situ ball milling at sub-zero temperatures resulted in an increase of the CO oxidation rate by roughly 4 orders of magnitude. This drastic and highly selective enhancement of CO oxidation showcases the potential of in situ ball milling in heterogeneous catalysis. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Dioxins reformation and destruction in secondary copper smelting fly ash under ball milling

    PubMed Central

    Cagnetta, Giovanni; Hassan, Mohammed Mansour; Huang, Jun; Yu, Gang; Weber, Roland

    2016-01-01

    Secondary copper recovery is attracting increasing interest because of the growth of copper containing waste including e-waste. The pyrometallurgical treatment in smelters is widely utilized, but it is known to produce waste fluxes containing a number of toxic pollutants due to the large amount of copper involved, which catalyses the formation of polychlorinated dibenzo-p-dioxins and dibenzofurans (“dioxins”). Dioxins are generated in secondary copper smelters on fly ash as their major source, resulting in highly contaminated residues. In order to assess the toxicity of this waste, an analysis of dioxin-like compounds was carried out. High levels were detected (79,090 ng TEQ kg−1) in the ash, above the Basel Convention low POPs content (15,000 ng TEQ kg−1) highlighting the hazardousness of this waste. Experimental tests of high energy ball milling with calcium oxide and silica were executed to assess its effectiveness to detoxify such fly ash. Mechanochemical treatment obtained 76% dioxins reduction in 4 h, but longer milling time induced a partial de novo formation of dioxins catalysed by copper. Nevertheless, after 12 h treatment the dioxin content was substantially decreased (85% reduction) and the copper, thanks to the phenomena of incorporation and amorphization that occur during milling, was almost inactivated. PMID:26975802

  3. Efficient destruction of hexachlorobenzene by calcium carbide through mechanochemical reaction in a planetary ball mill.

    PubMed

    Li, Yingjie; Liu, Qingnan; Li, Wenfeng; Lu, Yingzhou; Meng, Hong; Li, Chunxi

    2017-01-01

    Mechanochemical destruction (MCD) is a good alternative to traditional incineration for the destruction of persistent organic pollutants (POPs), like hexachlorobenzene (HCB), and the key is to find an efficient co-milling reagent. Toward this aim, HCB was milled with various reagents in a planetary ball mill at room temperature, and CaC2 was found to be the best one. HCB can be destroyed completely within 20 min at a mass ratio of CaC2/HCB = 0.9 and a rotation speed of 300 rpm. The ground samples were characterized by X-ray diffraction, X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. The results show that the destruction products are nonhazardous CaCl2 and carbon material with both crystalline and amorphous structures. On these bases, possible reaction pathways were proposed. Considering its excellent efficiency and safety, CaC2 may be the most feasible co-milling regent for MCD treatment of HCB. Further, the results are instructive for the destruction of other POPs.

  4. Dioxins reformation and destruction in secondary copper smelting fly ash under ball milling

    NASA Astrophysics Data System (ADS)

    Cagnetta, Giovanni; Hassan, Mohammed Mansour; Huang, Jun; Yu, Gang; Weber, Roland

    2016-03-01

    Secondary copper recovery is attracting increasing interest because of the growth of copper containing waste including e-waste. The pyrometallurgical treatment in smelters is widely utilized, but it is known to produce waste fluxes containing a number of toxic pollutants due to the large amount of copper involved, which catalyses the formation of polychlorinated dibenzo-p-dioxins and dibenzofurans (“dioxins”). Dioxins are generated in secondary copper smelters on fly ash as their major source, resulting in highly contaminated residues. In order to assess the toxicity of this waste, an analysis of dioxin-like compounds was carried out. High levels were detected (79,090 ng TEQ kg‑1) in the ash, above the Basel Convention low POPs content (15,000 ng TEQ kg‑1) highlighting the hazardousness of this waste. Experimental tests of high energy ball milling with calcium oxide and silica were executed to assess its effectiveness to detoxify such fly ash. Mechanochemical treatment obtained 76% dioxins reduction in 4 h, but longer milling time induced a partial de novo formation of dioxins catalysed by copper. Nevertheless, after 12 h treatment the dioxin content was substantially decreased (85% reduction) and the copper, thanks to the phenomena of incorporation and amorphization that occur during milling, was almost inactivated.

  5. Synthesis of magnetite nanoparticles by high energy ball milling

    NASA Astrophysics Data System (ADS)

    de Carvalho, J. F.; de Medeiros, S. N.; Morales, M. A.; Dantas, A. L.; Carriço, A. S.

    2013-06-01

    We report on the preparation of magnetite nanoparticles, with size ranging from 12 nm to 20 nm, by high energy ball milling. The synthesis is made using stoichiometric amounts of distilled water and metallic iron powder. The milled powder samples were analyzed by Mossbauer spectroscopy (MS), X-ray diffraction (XRD) and vibrating sample magnetometry (VSM). Our results indicate that the milling time is a key parameter of the synthesis. By increasing the milling time one achieves high purity magnetite samples. Also, the particle size decreases with the milling time. The sample milled during 10 h contained a fraction of 56 nm metallic Fe particles and 20 nm magnetite particles. By increasing the milling time to 96 h we have obtained a sample that is mainly composed of 12 nm magnetite particles. MS performed at room temperature showed a spectrum consisting of two sextets with hyperfine parameters related to iron ions occupying octahedral (A) and tetrahedral (B) sites. We have used a self-consistent method to investigate the impact of the dipolar interaction to drive the system to a magnetically blocked regime.

  6. Crystal structure of ball-milled mixture of sodium chloride and magnesium chloride-ethanol adduct

    SciTech Connect

    Jiang Xue; Tian Xiuzhi; Fan Zhiqiang

    2008-02-05

    NaCl doped MgCl{sub 2}.nEtOH adducts were prepared by ball-milling MgCl{sub 2}.2.5EtOH with NaCl. Both the ball-milled MgCl{sub 2}.nEtOH/NaCl mixture and pure MgCl{sub 2}.2.5EtOH adducts were analyzed by X-ray diffraction (XRD), transmission electron microscope (TEM), thermogravimetry (TG) and differencial scanning calorimetry (DSC). A simple MgCl{sub 2}.nEtOH/NaCl mixture without ball-milling treatment was also studied for comparison. Two kinds of mixed crystals, Na{sub 2}MgCl{sub 4} and NaMgCl{sub 3}, were found to be formed in a ball-milled mixture that contained 16 mol.% NaCl. TG and DSC analysis of the samples also provided indirect evidences supporting the presence of the mixed crystals in the ball-milled mixture. Adding certain amounts of NaCl in MgCl{sub 2}.2.5EtOH adduct, either by co-milling or by simple mixing, greatly increased the thermal stability of the adduct, but thermal decomposition behaviour of the ball-milled mixture was still different from that of a simple mixture.

  7. Response to Thermal Exposure of Ball-Milled Aluminum-Borax Powder Blends

    NASA Astrophysics Data System (ADS)

    Birol, Yucel

    2013-04-01

    Aluminum-borax powder mixtures were ball milled and heated above 873 K (600 °C) to produce Al-B master alloys. Ball-milled powder blends reveal interpenetrating layers of deformed aluminum and borax grains that are increasingly refined with increasing milling time. Thermal exposure of the ball-milled powder blends facilitates a series of thermite reactions between these layers. Borax, dehydrated during heating, is reduced by Al, and B thus generated reacts with excess Al to produce AlB2 particles dispersed across the aluminum grains starting at 873 K (600 °C). AlB2 particles start to form along the interface of the aluminum and borax layers. Once nucleated, these particles grow readily to become hexagonal-shaped crystals that traverse the aluminum grains with increasing temperatures as evidenced by the increase in the size as well as in the number of the AlB2 particles. Ball milling for 1 hour suffices to achieve a thermite reaction between borax and aluminum. Ball milling further does not impact the response of the powder blend to thermal exposure. The nucleation-reaction sites are multiplied, however, with increasing milling time and thus insure a higher number of smaller AlB2 particles. The size of the AlB2 platelets may be adjusted with the ball milling time.

  8. High energy ball milling and supercritical carbon dioxide impregnation as co-processing methods to improve dissolution of tadalafil.

    PubMed

    Krupa, Anna; Descamps, Marc; Willart, Jean-François; Jachowicz, Renata; Danède, Florence

    2016-12-01

    Tadalafil (TD) is a crystalline drug of a high melting point (Tm=299°C) and limited solubility in water (<5μg/mL). These properties may result in reduced and variable bioavailability after oral administration. Since the melting of TD is followed by its decomposition, the drug processing at high temperatures is limited. The aim of the research is, therefore, to improve the dissolution of TD by its co-processing with the hydrophilic polymer Soluplus® (SL) at temperatures below 40°C. In this study, two methods, i.e. high energy ball-milling and supercritical carbon dioxide impregnation (scCO2) are compared, with the aim to predict their suitability for the vitrification of TD. The influence of the amount of SL and the kind of co-processing method on TD thermal properties is analyzed. The results show that only the high energy ball milling process makes it possible to obtain a completely amorphous form of TD, with the characteristic X-ray 'halo' pattern. The intensity of the Bragg peaks diminishes for all the formulations treated with scCO2, but these samples remain crystalline. The MDSC results show that high energy ball milling is capable of forcing the mixing of TD and SL at a molecular level, providing a homogeneous amorphous solid solution. The glass transition temperatures (Tg), determined for the co-milled formulations, range from 79°C to 139°C and they are higher than Tg of pure SL (ca. 70°C) and lower than Tg of pure TD (ca. 149°C). In contrast to the co-milled formulations which are in the form of powder, all the formulations after scCO2 impregnation form a hard residue, sticking to the reaction vessel, which needs to be ground before analysis or further processing. Finally, the dissolution studies show that not only has SL a beneficial effect on the amount of TD dissolved, but also both co-processing methods make the dissolution enhancement of TD possible. After co-processing by scCO2, the amount of TD dissolved increases with the decreasing amount

  9. Role of carbon order in structural transformations and hydrogen evolution induced by reactive ball milling in cyclohexene

    SciTech Connect

    Sakti, A.; Wonderling, N.M.; Clifford, C.E.B.; Badding, J.V.; Lueking, A.D.

    2008-11-15

    Demineralized Summit (DS) anthracite, DS annealed at 1673 K, and graphite are used to explore the effect of precursor order on structural transformations and H{sub 2} evolution that result during reactive ball milling. Carbon structure was assessed before and after milling with temperature-programmed oxidation, X-ray diffraction (XRD), ultraviolet Raman spectroscopy, N{sub 2} adsorption, He density, and solvent swelling. Graphite milled in cyclohexene is primarily nanocrystalline graphite, with 8 wt % amorphous content leading to low-temperature oxidation, swelling, increased surface area, and mesoporosity. Milling the disordered DS leads to signs of increased sp{sup 2} clustering, increased cross-linking, a significant ultramicroporosity with pores less than 8 angstrom, and low-temperature H{sub 2} evolution. The carbon fraction of annealed DS behaves similarly to graphite in the mill.

  10. Investigation of griseofulvin and hydroxypropylmethyl cellulose acetate succinate miscibility in ball milled solid dispersions.

    PubMed

    Al-Obaidi, Hisham; Lawrence, M Jayne; Al-Saden, Noor; Ke, Peng

    2013-02-25

    Solid dispersions of varying weight ratios compositions of the nonionic drug, griseofulvin and the hydrophilic, anionic polymer, hydroxylpropylmethyl cellulose acetate succinate, have been prepared by ball milling and the resulting samples characterized using a combination of Fourier transform infra-red spectroscopy, X-ray powder diffraction and differential scanning calorimetry. The results suggest that griseofulvin forms hydrogen bonds with the hydroxylpropylmethyl cellulose acetate succinate polymer when prepared in the form of a solid dispersion but not when prepared in a physical mixture of the same composition. As anticipated, the actual measured glass transition temperature of the solid dispersions displayed a linear relationship between that predicted using the Gordon-Taylor and Fox equations assuming ideal mixing, but interestingly only at griseofulvin contents less than 50 wt%. At griseofulvin concentrations greater than this, the measured glass transition temperature of the solid dispersions was almost constant. Furthermore, the crystalline content of the solid dispersions, as determined by differential scanning calorimetry and X-ray powder diffraction followed a similar trend in that the crystalline content significantly decreased at ratios less than 50 wt% of griseofulvin. When the physical mixtures of griseofulvin and the hydroxylpropylmethyl cellulose acetate succinate polymer were analyzed using the Flory-Huggins model, a negative free energy of mixing with an interaction parameter of -0.23 were obtained. Taken together these results suggest that anionic hydrophilic hydroxylpropylmethyl cellulose acetate succinate polymer is a good solvent for crystalline nonionic griseofulvin with the solubility of griseofulvin in the solid dispersion being was estimated to be within the range 40-50 wt%. Below this solubility limit, the amorphous drug exists as amorphous glassy solution while above these values the system is supersaturated and glassy suspension and

  11. Effects and mechanism of ball milling on torrefaction of pine sawdust.

    PubMed

    Gong, Chunxiao; Huang, Jing; Feng, Chen; Wang, Guanghui; Tabil, Lope; Wang, Decheng

    2016-08-01

    The effects and mechanism of ball milling on the torrefaction process were studied. Ball- and hammer-milled (screen size 1mm) pine sawdust samples were torrefied at three temperatures (230, 260, and 290°C) and two durations (30 and 60min) to investigate into their torrefaction behavior and physicochemical properties. The results showed that, under identical torrefaction conditions, torrefied ball-milled pine sawdust had a higher carbon content and fixed carbon, and lower hydrogen and oxygen contents than torrefied hammer-milled pine sawdust. Torrefied ball-milled pine sawdust produced lower mass and energy yields, but higher heating values than torrefied hammer-milled pine sawdust. Ball milling destroyed the crystalline structure of cellulose and thus reduced the thermal stability of hemicellulose, cellulose, and lignin, causing them to degrade at relatively lower temperatures. In conclusion, biomass pretreated with a combination of ball milling and torrefaction has the potential to produce an alternative fuel to coal. Copyright © 2016 Elsevier Ltd. All rights reserved.

  12. Preparation of magnesium ferrite nanoparticles by ultrasonic wave-assisted aqueous solution ball milling.

    PubMed

    Chen, Ding; Li, Dian-yi; Zhang, Ying-zhe; Kang, Zhi-tao

    2013-11-01

    Magnesium ferrite, MgFe2O4 nanoparticles with high saturation magnetization were successfully synthesized using ultrasonic wave-assisted ball milling. In this study, the raw materials were 4MgCO3·Mg(OH)2·5H2O and Fe2O3 powders and the grinding media was stainless steel ball. The average particle diameter of the product MgFe2O4 powders was 20 nm and the saturation magnetization of them reached 54.8 emu/g. The different results of aqueous solution ball milling with and without ultrasonic wave revealed that it was the coupling effect of ultrasonic wave and mechanical force that played an important role during the synthesis of MgFe2O4. In addition, the effect of the frequency of the ultrasonic wave on the ball milling process was investigated.

  13. Remediation of oil-contaminated sand by coal agglomeration using ball milling.

    PubMed

    Shin, Yu-Jen; Shen, Yun-Hwei

    2011-10-01

    The mechanical shear force provided by a less energy intensive device (usually operating at 20-200 rpm), a ball mill, was used toperform coal agglomeration and its effects on remediation of a model fuel oil-contaminated sand were evaluated. Important process parameters such as the amount of coal added, milling time, milling speed and the size of milling elements are discussed. The results suggested that highly hydrophobic oil-coal agglomerates, formed by adding suitable amounts of coal into the oil-contaminated sand, could be mechanically liberated from cleaned sand during ball milling and recovered as a surface coating on the steel balls. Over 90% removal of oil from oil-contaminated sand was achieved with 6 wt% of coal addition and an optimum ball milling time of 20 min and speed of 200 rpm. This novel process has considerable potential for cleaning oil-contaminated sands.

  14. Ferromagnetic behavior of nanocrystalline Cu-Mn alloy prepared by ball milling

    NASA Astrophysics Data System (ADS)

    Mondal, B. N.; Sardar, G.; Nath, D. N.; Chattopadhyay, P. P.

    2014-12-01

    50Cu-50Mn (wt%) alloy was produced by ball milling. The milling was continued up to 30 h followed by isothermal annealing over a four interval of temperature from 350 to 650 °C held for 1 h. Crystallite size, lattice strain, lattice parameter were determined by Rietveld refinement structure analysis of X-ray diffraction data. The amount of dissolved/precipitated Mn (wt%) after ball milling/milling followed by annealing was calculated by quantative phase analysis (QPA). The increase of coercivity could be attributed to the introduction of lattice strain and reduction of crystallite size as a function of milling time. Electron paramagnetic resonance and superconducting quantum interface device analysis indicate that soft ferromagnetic behavior has been achieved by ball milled and annealed Cu-Mn alloy. The maximum coercivity value of Cu-Mn alloy obtained after annealing at 350 °C for 1 h is 277 Oe.

  15. Structural and magnetic stability of high energy ball milled Co2MnSi

    NASA Astrophysics Data System (ADS)

    Vinesh, A.; Sudheesh, V. D.; Sebastian, Varkey; Lakshmi, N.; Venugopalan, K.

    2015-07-01

    Structural and magnetic properties of ball milled Co2MnSi have been studied and compared with that of ordered bulk sample. The milled sample (with average size determined using the Williamson-Hall method) shows that the chemical ordering for this sample is very stable and is little effected by high energy ball milling. However, the reduction in the saturation magnetic moment of the milled sample shows that there is spin disordering induced on ball milling - attributable to the formation of a magnetically dead layer at the surface of the nano-sized samples. The ordered sample (unmilled) has a saturation moment value of 4.4 μB per formula unit at room temperature and is in agreement with the prediction of Slater Pauling curve. On milling it reduces to ~3 μB per formula unit at room temperature with an accompanying increase in the coercivity, retentivity and squareness factor.

  16. Effect of ball milling and heat treatment process on MnBi powders magnetic properties

    SciTech Connect

    Xie, Wei; Polikarpov, Evgueni; Choi, Jung-Pyung; Bowden, Mark E.; Sun, Kewei; Cui, Jun

    2016-09-01

    The metallic compound MnBi has high intrinsic coercivity with large positive temperature coefficient. The coercivity of MnBi exceeds 12 kOe and 26 kOe at 300 K and 523 K, respectively. Hence MnBi is a good candidate for the hard phase in exchange coupled nanocomposite magnets. In order to maximize the loading of the soft phase, the size of the MnBi particle has to be close to 500 nm, the size of single magnetic domain. Low energy milling is the common method to reduce MnBi particle size. However, only 3-7 mu m size particle can be achieved without significant decomposition. Here, we report our effort on preparing submicron MnBi powders using traditional powder metallurgy methods. Mn55Bi45 magnetic powders were prepared using arc melting method, followed by a series of thermal-mechanical treatment to improve purity, and finished with low energy ball milling at cryogenic temperature to achieve submicron particle size. The Mn55Bi45 powders were decomposed during ball milling process and recovered during 24 h 290 degrees C annealing process. With increasing ball-milling time, the saturation magnetization of MnBi decreases, while the coercivity increases. Annealing after ball milling recovers some of the magnetization, indicating the decomposition occurred during the ball-milling process can be reversed. The coercivity of Mn55Bi45 powders are also improved as a result of the heat treatment at 290 degrees C for 24 h. The world record magnetization 71.2 emu/g measured applying a field of 23 kOe has been achieved via low energy ball mill at room temperature

  17. Effects of ball-milling on PLGA polymer and its implication on lansoprazole-loaded nanoparticles

    PubMed Central

    Shabir, Anjumn; Alhusban, Farhan; Perrie, Yvonne; Mohammed, Afzal R.

    2011-01-01

    PLGA is a biodegradable polymer utilised widely in pharmaceutical research for the encapsulation of a wide range of drugs as nano particulate systems. This study investigates the impact of rotary ball milling on the physical properties of PLGA and its influence on nanoparticle formation prepared using the solvent displacement technique. By applying mechanical stress to the polymer and altering its physical appearance and molecular weight, the loading of lansoprazole within the nanoparticles was increased to 96%, with a reduction in particle size. The results indicate that rotary ball milling significantly reduces particle size, increases lansoprazole loading and improves the release profile for lansoprazole loaded PLGA nanoparticles PMID:24826005

  18. Factors influencing the ball milling of Si3N4 in water

    NASA Technical Reports Server (NTRS)

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

    1985-01-01

    A statistical study of the ball milling of Si3N4 powder in Si3N4 hardware was undertaken to understand how the resulting increase in specific surface area is related to solids loading and mill speed. An attempt was made to optimize milling conditions. The degree of communication was more dependent upon solids loading than mill speed. A practical grinding limit between 0.5 and 0.75 microns was achieved in 144 hr independent of solids loading. Ball mill wear and media wear were independent of both solids loading and mill speed.

  19. Factors influencing the ball milling of Si3N4 in water

    NASA Technical Reports Server (NTRS)

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

    1985-01-01

    A statistical study of the ball milling of Si3N4 powder in Si3N4 hardware was undertaken to understand how the resulting increase in specific surface area is related to solids loading and mill speed. An attempt was made to optimize milling conditions. The degree of communication was more dependent upon solids loading than mill speed. A practical grinding limit between 0.5 and 0.75 microns was achieved in 144 hr independent of solids loading. Ball mill wear and media wear were independent of both solids loading and mill speed.

  20. The Key Role of Ball Milling Time in the Microstructure and Mechanical Property of Ni-TiCNP Composites

    NASA Astrophysics Data System (ADS)

    Zhou, Xiaoling; Huang, Hefei; Xie, Ruobing; Yang, Chao; Li, Zhijun; Jiang, Li; Ye, Xiangxi; Xu, Hongjie

    2016-12-01

    Titanium carbide nanoparticle-reinforced nickel-based alloys (Ni-TiCNP composites) with ball milling time ranging from 8 to 72 h were prepared by ball milling and spark plasma sintering. Transmission electron microscopy (TEM) and scanning electron microscopy equipped with electron backscatter diffraction were used to characterize the microstructures. Their hardness and tensile properties were measured using the Vickers pyramid method and tensile tests. TEM results showed that a slight coarsening of TiCNP occurred during the ball milling process. The grain sizes of the Ni-TiCNP composites with various ball milling times were different, but they were all much smaller than those of the pure Ni. In all cases, the Ni-TiCNP composites showed higher strengths and hardness values than the unreinforced pure nickel. Furthermore, the strength of the Ni-TiCNP composites increased initially and then decreased as a function of ball milling time. The maximum strengths occurred in the 24-h ball milling sample, which presented the lowest average grain size. The Hall-Petch strengthening was suggested to be the main reason responsible for such variations in mechanical properties. Additionally, the elongation percentage of the Ni-TiCNP composites decreased gradually with ball milling time. This may be caused by the change of microvoids in the composite as the ball milling time varies, which is also related to their fracture behavior.

  1. Structural and microstructural changes in monoclinic ZrO{sub 2} during the ball-milling with stainless steel assembly

    SciTech Connect

    Stefanic, G. . E-mail: stefanic@irb.hr; Music, S.; Gajovic, A.

    2006-04-13

    High-energy ball-milling of monoclinic ZrO{sub 2} was performed in air using the planetary ball mill with a stainless steel milling assembly. Structural and microstructural changes during the ball-milling were monitored using X-ray powder diffraction, Raman spectroscopy, Moessbauer spectroscopy, field emission scanning electron microscopy and energy dispersive X-ray spectrometry. The results of line broadening analysis indicated a decrease in the crystallite size and an increase in the microstrains with the ball-milling time increased up to {approx}150 min. The results of quantitative phase analysis indicated the presence of a very small amount of tetragonal ZrO{sub 2} phase in this early stage of ball-milling. The onset of m-ZrO{sub 2} {sup {yields}} t-ZrO{sub 2} transition occurred between 10 and 15 h of ball-milling, which resulted in a complete transition after 20 h of ball-milling. Further ball-milling caused a decrease of the t-ZrO{sub 2} lattice parameters followed by a probable transition into c-ZrO{sub 2}. It was concluded that the stabilization of t- and c-ZrO{sub 2} polymorphs at RT can be attributed to the incorporation of aliovalent cations (Fe{sup 2+}, Fe{sup 3+} and Cr{sup 3+}) introduced into the sample due to the wear and oxidation of the milling media.

  2. Synthesis of Fe/SiO{sub 2} and iron oxides/SiO{sub 2} nanocomposites by long-term ball milling

    SciTech Connect

    Pozo López, G.; Condó, A.M.; Urreta, S.E.; Silvetti, S.P.

    2014-01-01

    Graphical abstract: - Highlights: • Iron–iron oxides/silica composites are synthesized by long term dry ball-milling. • Bcc iron and α-quartz powders are used as precursors. • Surface effects enhance coercivity in iron/silica nanocomposites. • In spite of their small size, about 10 nm, iron particles are ferromagnetic. • Ferro and superparamagnetic particles are found in maghemite/silica composites. - Abstract: Iron oxide/SiO{sub 2} nanocomposites are synthesized by dry ball-milling a mixture of bcc Fe and α-quartz powders for prolonged times. A sequence of nanocomposites is obtained, with small magnetic particles dispersed in a non magnetic, amorphous matrix. The powders are characterized by X-ray diffraction and transmission electron microscopy. The magnetic hysteresis properties are investigated in the range 50–300 K. After 120 h milling, deformed, non-spherical, α-Fe nanocrystallites of about 10 nm in size and very few small (<10 nm) maghemite particles are found. At room temperature, iron particles are ferromagnetic and a large effective magnetic anisotropy is estimated, which is mainly attributed to surface effects. Between 160 and 200 h milling, maghemite nanoparticles are observed while after 220 h grinding, hematite phase appears; after 340 h milling, the sample consists of ferromagnetic hematite particles with a broad size distribution (5–50 nm) embedded in an amorphous matrix.

  3. Ball milling pretreatment of oil palm biomass for enhancing enzymatic hydrolysis.

    PubMed

    Zakaria, Mohd Rafein; Fujimoto, Shinji; Hirata, Satoshi; Hassan, Mohd Ali

    2014-08-01

    Oil palm biomass, namely empty fruit bunch and frond fiber, were pretreated using a planetary ball mill. Particle sizes and crystallinity index values of the oil palm biomass were significantly reduced with extended ball mill processing time. The treatment efficiency was evaluated by the generation of glucose, xylose, and total sugar conversion yields from the pretreatment process compared to the amount of sugars from raw materials. Glucose and xylose contents were determined using high-performance liquid chromatography. An increasing trend in glucose and xylose yield as well as total sugar conversion yield was observed with decreasing particle size and crystallinity index. Oil palm frond fiber exhibited the best material yields using ball milling pretreatment with generated glucose, xylose, and total sugar conversion yields of 87.0, 81.6, and 85.4%, respectively. In contrast, oil palm empty fruit bunch afforded glucose and xylose of 70.0 and 82.3%, respectively. The results obtained in this study showed that ball mill-treated oil palm biomass is a suitable pretreatment method for high conversion of glucose and xylose.

  4. Removal of hexavalent chromium from contaminated waters by ultrasound-assisted aqueous solution ball milling.

    PubMed

    Chen, Lin; Chen, Zhenhua; Chen, Ding; Xiong, Wei

    2017-02-01

    Batch mode experiments were conducted to study the removal of hexavalent chromium (Cr(VI)) from aqueous solutions using ultrasound-assisted aqueous solution ball milling. The results show that the reduction rate of Cr(VI) by ultrasound-assisted aqueous solution ball milling was significantly faster than that by ball milling or ultrasound treatment alone, and an initial Cr(VI) concentration of 166mg/L could be decreased to 0.35mg/L at 120min. The decisive factors, including initial concentration of Cr(VI), pH value, ultrasonic frequency and filling gas, were studied. It was found that the optimal ultrasonic frequency for ultrasound-assisted aqueous solution ball milling device was 20kHz, and the rate of Cr(VI) reduction as a function of filling gas followed the order: Ar>air>N2>O2. Samples were characterized by X-ray diffraction, fluorescence measurements, atomic absorption and the diphenylcarbazide colorimetric method. The Cr(VI) transformed into a precipitate that could be removed from the contaminated water, after which the water could be reused. Copyright © 2016. Published by Elsevier B.V.

  5. Non-equilibrium microscale thermomechanical modeling of bimetallic particulate fractal structures during ball milling fabrication

    NASA Astrophysics Data System (ADS)

    Aureli, Matteo; Doumanidis, Constantine C.; Gunduz, I. E.; Hussien, Aseel Gamal Suliman; Liao, Yiliang; Jaffar, Syed Murtaza; Rebholz, Claus; Doumanidis, Charalabos C.

    2017-07-01

    Nanostructured bimetallic reactive multilayers can be conveniently produced by ball milling of elemental powders. This research explores the non-equilibrium microscale conductive thermal transport in ball-milled particulate fractal structures during fabrication, arising from heat dissipation by bulk plastic deformation and surface friction. Upon impactor collisions, temperature increments are determined at interface joints and domain volumes using Green's functions, mirrored by source images with respect to warped ellipsoid domain boundaries. Heat source efficiency is calibrated via laboratory data to compensate for thermal expansion and impactor inelasticity, and the thermal analysis is coupled to a dynamic mechanics model of the particulate fracture. This thermomechanical model shows good agreement with the fractal dimensions of the observed microstructure from ball milling experiments. The model is intended to provide a comprehensive physical understanding of the fundamental process mechanism. In addition, the model could serve as a real-time thermal observer for closed-loop process control, as well as for interfacial diffusion and reaction analysis during ball milling.

  6. Microstructure and morphological study of ball-milled metal matrix nanocomposites

    NASA Astrophysics Data System (ADS)

    Afkham, Y.; Khosroshahi, R. Azari; Kheirifard, R.; Mousavian, R. Taherzadeh; Brabazon, D.

    2017-08-01

    Due to the difficulty of preparation and beneficial properties achievable, copper and iron matrix nanocomposites are materials for which fabrication via the powder metallurgy route is attracting increasing research interest. The presence of ceramic nanoparticles in their matrix can lead to considerable changes in the microstructure and morphology. The effects of the type of metallic matrix and ceramic nanoparticle on the distribution of nano reinforcements and the morphology of ball-milled composite powders were evaluated in this study. For this purpose, 25 wt % of Al2O3 and SiC nanoparticles were separately ball-milled in the presence of iron and copper metals. The SEM, FESEM, and XRD results indicated that as-received nanoparticles, which were agglomerated before milling, were partially separated and embedded in the matrix of both the metals after the initial stages of ball milling, while prolonged milling was not found to further affect the distribution of nanoparticles. It was also observed that the Al2O3 phase was not thermodynamically stable during ball milling with copper powders. Finally, it was found that the presence of nanoparticles considerably reduce the average size of metallic powder particles.

  7. Synthesis of aluminum nitride powders from a plasma-assisted ball milled precursor through carbothermal reaction

    SciTech Connect

    Liu, Zhi-jie; Dai, Le-yang; Yang, De-zheng; Wang, Sen; Zhang, Bao-jian; Wang, Wen-chun; Cheng, Tie-han

    2015-01-15

    Highlights: • A novel and high efficiency synthesizing AlN powders method combining mechanical ball milling and DBDP has been developed. • The particle size, the crystallite size, the lattice distortion, the morphology of Al{sub 2}O{sub 3} powders, and the AlN conversion rate are investigated and compared under the ball milled Al{sub 2}O{sub 3} powders with DBDP and without DBDP. • The ball milled Al{sub 2}O{sub 3} powders with DBDP have small spherical structure morphology with very fine particles size and high specific surface area, which result in a higher chemical efficiency and a higher AlN conversion rate at lower thermal temperature. - Abstract: In this paper, aluminum nitride (AlN) powers have been produced with a novel and high efficiency method by thermal annealing at 1100–1600 °C of alumina (Al{sub 2}O{sub 3}) powders which were previously ball milled for various time up to 40 h with and without the assistant of dielectric barrier discharge plasma (DBDP). The ball milled Al{sub 2}O{sub 3} powders with DBDP and without DBDP and the corresponding synthesized AlN powers are characterized by X-ray diffraction, scanning electron microscope, and transmission electron microscopy. From the characteristics of the ball milled Al{sub 2}O{sub 3} powders with DBDP and without DBDP, it can be seen that the ball milled Al{sub 2}O{sub 3} powders with DBDP have small spherical structure morphology with very fine particles size and high specific surface area, which result in a higher chemical efficiency and a higher AlN conversion rate at lower thermal temperature. Meanwhile, the synthesized AlN powders can be known as hexagonal AlN with fine crystal morphology and irregular lump-like structure, and have uniform distribution with the average particle size of about between 500 nm and 1000 nm. This provides an important method for fabricating ultra fine powders and synthesizing nitrogen compounds.

  8. Atomic scale study of ball milled Ni-Fe{sub 2}O{sub 3} using Mössbauer spectroscopy

    SciTech Connect

    Yadav, Ravi Kumar; Govindaraj, R. Vinod, K.; Kumar, P. A. Manoj; Amarendra, G.

    2016-05-23

    Evolution of hyperfine fields at Fe atoms has been studied in a detailed manner in a mixture of Ni and α-Fe{sub 2}O{sub 3} subjected to high energy ball milling using Mossbauer spectroscopy. Mossbauer results indicate the dispersion of α-Fe{sub 2}O{sub 3} particles in Ni matrix in the as ball milled condition. Evolution of α-Fe{sub 2}O{sub 3} due to ball milling, reduction of the valence of associated Fe and possible interaction between the oxide particles with Ni in the matrix due to annealing treatments has been elucidated in the present study.

  9. Magnetic property and microstructure of single crystalline Nd2Fe14B ultrafine particles ball milled from HDDR powders

    SciTech Connect

    Li, WF; Hu, XC; Cui, BZ; Yang, JB; Han, JZ; Hadjipanayis, GC

    2013-08-01

    In this work we report the microstructure and magnetic property of single crystalline Nd2Fe14B ultrafine particles ball milled from HDDR Nd-Fe-B alloys. The average size of the particles is 283 nm, and TEM observation reveals that these particles are single crystalline. The coercivity of these particles is 6.0 kOe, which is much higher than that of the particles ball milled from sintered and hot pressed Nd-Fe-B magnets. Micromagnetic analysis shows that the coercivity degradation is caused by surface damage during ball milling. (C) 2013 Elsevier B.V. All rights reserved.

  10. Study of the nanocrystalline ball-milled Cu80(Fe0.3Co0.7)20 compound

    NASA Astrophysics Data System (ADS)

    Galdeano, S.; Mathon, M. H.; Chaffron, L.; André, G.; Vincent, E.; Traverse, A.; de Novion, C. H.

    The influence of the ball-milling temperature and intensity has been studied on the nanostructure of the Cu80(Fe0.3Co0.7)20 compound. The ball milling of mixed powders of Cu-Fe and Cu-Co supersaturated solid solutions allows the formation of a very fine Fe30Co70 precipitation in the Cu matrix, interesting for its magnetoresistive properties. Powder neutron diffraction and SANS, coupled to magnetic measurements and EXAFS experiments, allowed us to correlate the ball-milling conditions to the nanostructure and the magnetic properties of the ternary compound.

  11. Atomic scale study of ball milled Ni-Fe2O3 using Mössbauer spectroscopy

    NASA Astrophysics Data System (ADS)

    Yadav, Ravi Kumar; Govindaraj, R.; Vinod, K.; Kumar, P. A. Manoj; Amarendra, G.

    2016-05-01

    Evolution of hyperfine fields at Fe atoms has been studied in a detailed manner in a mixture of Ni and α-Fe2O3 subjected to high energy ball milling using Mossbauer spectroscopy. Mossbauer results indicate the dispersion of α-Fe2O3 particles in Ni matrix in the as ball milled condition. Evolution of α-Fe2O3 due to ball milling, reduction of the valence of associated Fe and possible interaction between the oxide particles with Ni in the matrix due to annealing treatments has been elucidated in the present study.

  12. Comparative Study by MS and XRD of Fe50Al50 Alloys Produced by Mechanical Alloying, Using Different Ball Mills

    NASA Astrophysics Data System (ADS)

    Rojas Martínez, Y.; Pérez Alcázar, G. A.; Bustos Rodríguez, H.; Oyola Lozano, D.

    2005-02-01

    In this work we report a comparative study of the magnetic and structural properties of Fe50Al50 alloys produced by mechanical alloying using two different planetary ball mills with the same ball mass to powder mass relation. The Fe50Al50 sample milled during 48 h using the Fritsch planetary ball mill pulverisette 5 and balls of 20 mm, presents only a bcc alloy phase with a majority of paramagnetic sites, whereas that sample milled during the same time using the Fritsch planetary ball mill pulverisette 7 with balls of 15 mm, presents a bcc alloy phase with paramagnetic site (doublet) and a majority of ferromagnetic sites which include pure Fe. However for 72 h of milling this sample presents a bcc paramagnetic phase, very similar to that prepared with the first system during 48 h. These results show that the conditions used in the first ball mill equipment make more efficient the milling process.

  13. Electromagnetic properties of Co flaky particles prepared via ball-milling method

    NASA Astrophysics Data System (ADS)

    Liu, Chao; Jiang, Jian-Tang; Yuan, Yong; Gong, Yuan-Xun; Zhen, Liang

    2016-10-01

    Flaky cobalt particles with different aspect ratio were produced with ball-milling method. The phase structure and morphology of the particles were identified by XRD analysis and SEM observation. The static magnetic and electromagnetic properties of the particles were measured and effects of shape, microstructure and filling fraction were investigated. Phase transition from fcc lattice to hcp lattice occur due to the drive of ball-milling is responsible for the largely increased coercivity. Particles with high aspect ratio are found to possess high permittivity and permeability, compelling the frequency of absorption peak to shift to low frequency. Coatings using cobalt particles milled for 20 h as fillers present a RL peak of -33 dB at 8 GHz at the thickness of 2.5 mm together with a broad effective absorbing (RL below -10 dB) bandwidth covering 6-10 GHz.

  14. Excess lithium storage in LiFePO4-Carbon interface by ball-milling

    NASA Astrophysics Data System (ADS)

    Guo, Hua; Song, Xiaohe; Zheng, Jiaxin; Pan, Feng

    2016-07-01

    As one of the most popular cathode materials for high power lithium ion batteries (LIBs) of the electrical-vehicle (EV), lithium iron phosphate (LiFePO4 (LFP)) is limited to its relatively lower theoretical specific capacity of 170mAh g-1. To break the limits and further improve the capacity of LFP is promising but challenging. In this study, the ball-milling method is applied to the mixture of LFP and carbon, and the effective capacity larger than the theoretical one by 30mAh g-1 is achieved. It is demonstrated that ball-milling leads to the LFP-Carbon interface to store the excess Li-ions.

  15. Broadband Absorber for the Microwave Region Using Ball-Milled Graphite Gratings

    NASA Astrophysics Data System (ADS)

    Chen, Xiqiao; Zhang, Zilong; Wang, Zilin; Wang, Shuai; Heng, Liuyang; Zou, Yanhong

    2017-10-01

    A broadband absorber for the microwave region based on a dielectric structure with ball-milled graphite gratings has been proposed. In this absorber, electromagnetic waves in the frequency range of 5.4 to 18 GHz are absorbed efficiently with more than 90% absorptivity. The ball-milled graphite with high a imaginary part of its permittivity used in this work can exhibit dielectric loss to some extent, while there is almost no magnetic loss owing to its low permeability. By comparing the electric field of a single absorbing layer and our grating structure, we found that a λ/4 resonance mode with a narrowband property is excited in the single-layer structure, while the cavity-mode resonance and the edge diffraction effects are the main reasons for the broadband absorption of our designed grating structure. This result provides a guideline for microwave-absorbing materials to greatly extend their bandwidth using a simple structure.

  16. Magnetic properties of TbFe2 particles prepared by magnetic field assisted ball milling

    NASA Astrophysics Data System (ADS)

    Arout Chelvane, J.; Palit, Mithun; Basumatary, Himalay; Pandian, S.

    2013-10-01

    The alloy of TbFe2 was studied by ball milling with and without the presence of external magnetic field. While the structure and powder morphology of the alloy were investigated using scanning electron microscope and X-ray diffraction, the magnetization was investigated using vibrating sample and superconducting quantum interference device magnetometers. The rate of particle reduction with ball milling is comparatively higher in the presence of external magnetic field than without it. Consequently, owing to a large fraction of particles acquiring near single domain configuration under the field assisted milling condition, the coercivity derived from these particles are as high as 6500 Oe than that of particles obtained without the aid of external magnetic field which is around 3850 Oe. The field cooled low temperature magnetization exhibits a large coercivity and skew in the shape of the magnetization curve due to the large anisotropy.

  17. High-frequency induction heated sintering of ball milled Fe-WC nanocomposites

    NASA Astrophysics Data System (ADS)

    Zakeri, M.; Zanganeh, T.; Najafi, A.

    2013-07-01

    Fe-WC nanocomposites were successfully fabricated by high-frequency induction heated sintering of ball milled nanostructure powders. The ball milled powders were characterized by X-ray diffraction. Density measurements by the Archimedes method show that all sintered samples have the relative density higher than 95%. Studies on the effects of WC content, milling speed, and milling time indicate that a higher milling speed and a more WC content lead to the improvement of mechanical properties. There is a very good distribution of WC particles in the Fe matrix at the milling speed of 650 r/min. For the sintered sample 20-5-650 (20wt% WC, milling time of 5 h, and milled speed of 650 r/min), the maximum Brinell hardness and yield stress are obtained to be 3.25 GPa and 858 MPa, respectively. All sintered samples have brittle fracture during compression test except the sample 20-5-650.

  18. High energy ball milling study of Fe{sub 2}MnSn Heusler alloy

    SciTech Connect

    Jain, Vivek Kumar Lakshmi, N.; Jain, Vishal; Sijo, A. K.; Venugopalan, K.

    2015-06-24

    The structural and magnetic properties of as-melted and high energy ball milled alloy samples have been studied by X-ray diffraction, DC magnetization and electronic structure calculations by means of density functional theory. The observed properties are compared to that of the bulk sample. There is a very good enhancement of saturation magnetization and coercivity in the nano-sized samples as compared to bulk which is explained in terms of structural disordering and size effect.

  19. Effect of Surfactant Molecular Weight on Particle Morphology of SmCo5 Prepared by High Energy Ball Milling

    DTIC Science & Technology

    2014-04-01

    ball milling (HEBM) is a widely used technique for producing nanostructured magnetic materials with oleic acid (OA) being the most commonly utilized...2012) Surfactant-assisted high energy ball milling (HEBM) is a widely used technique for producing nanostructured magnetic materials with oleic acid ...nanostructured powders to the high temperatures required for surfactant removal is known to result in grain growth and oxi- dation.7,8 Oleic acid (OA) is the

  20. Effect of milling parameters on SmCo5 nanoflakes prepared by surfactant-assisted high energy ball milling

    NASA Astrophysics Data System (ADS)

    Pal, Santosh K.; Schultz, Ludwig; Gutfleisch, Oliver

    2013-01-01

    In this study, we discuss the effect of different milling parameters, such as the type and concentration of surfactants, milling energy, and milling time on the structural, morphological and magnetic properties of hard magnetic SmCo5 nanoflakes prepared by surfactant assisted high energy ball milling. Two kinds of surfactants, polyvinylpyrolidone (PVP) with ethanol and oleic acid (OA) with n-heptane, were used as milling media. Increase in surfactants concentration and decrease in milling energy result in the decrease of degree of amorphization and reduction in grain size with milling time. Milling at 200 rpm results in more homogeneous and thicker flakes with fewer fractions of nanoparticles as compared to milling at 800 rpm. Increase in surfactants concentration results in the increase of the aspect ratio of flakes. Due to better capping ability of OA, the degree of flaking is higher when milling in OA than that in case of PVP. A maximum coercivity of 2.3 T was obtained after milling for 1.0 and 2.0 h for 10 and 50 wt. % of OA, respectively, at 800 rpm. A maximum (BH)max of 23.8 MGOe (188.9 kJ m-3) and degree of texture of 93% were obtained for 10 wt. % OA after 10 h of milling at 200 rpm. The pronounced anisotropy and high coercivity of the nanoflakes should prove advantageous for the preparation of textured exchange spring magnets.

  1. Ball-milled solid dispersions of BCS Class IV drugs: Impact on the dissolution rate and intestinal permeability of acyclovir.

    PubMed

    Nart, Viviane; França, Maria Terezinha; Anzilaggo, Daiane; Riekes, Manoela Klüppel; Kratz, Jadel Müller; de Campos, Carlos Eduardo Maduro; Simões, Cláudia Maria Oliveira; Stulzer, Hellen Karine

    2015-08-01

    Acyclovir, an analog of 2'-deoxyguanosine, is one of the most important drugs in the current approved antiviral treatment. However, it's biopharmaceutical properties, contribute to acyclovir's poor oral bioavailability, which restricts the clinical use of the drug. In this view, the aim of this work was to improve the dissolution rate and intestinal permeability of acyclovir through the development of ball milling solid dispersions with the hydrophilic carriers Pluronic F68®, hydroxypropylmethyl cellulose K100M® and chitosan. Solid dispersions were obtained and completely characterized through different solid state techniques. The solid state data demonstrated a decrease in the crystallinity (amorphous phase and defects) and the presence of hydrogen bonds for SD HPMC and SD CTS. The enhancement of dissolution rates was observed for all SDs developed. In addition, no detrimental effects over the in vitro antiviral activity were detected. The solid dispersions with Pluronic F68® significantly improved the intestinal permeability of acyclovir across Caco-2 cells. In summary, the SDs developed in this study could be considered as potential systems for solid dosage forms containing acyclovir with superior biopharmaceutical properties.

  2. The effect of oxygen on ball milling of a near-equiatomic FeV sigma phase

    NASA Astrophysics Data System (ADS)

    Costa, B. F. O.; Le Caër, G.; Malaman, B.

    2008-10-01

    A coarse-grained near-equiatomic tetragonal sigma phase Fe48V52 is milled in argon in a vibratory mill with a small steady air supply. The oxygen content increases regularly at a rate of about 0.25at.%/h. Besides a classical short step, during which the sigma phase transforms into an alpha phase, two main steps occur. During the first step, from ˜40to˜140h of milling, the bcc alpha phase is enriched in iron and heterogeneous because of a preferential oxidation of vanadium atoms. The bcc phase is partially amorphized as it is when milling in the absence of oxygen and nanocrystalline vanadium oxides do form. The second step is characterized by the coarsening of vanadium oxide particles and by the formation of ternary ferrous oxides. The results are discussed in the light of a vacancy mechanism proposed recently to account for the high stability of oxide nanoclusters in oxide dispersion strengthened Fe-based alloys processed by ball milling.

  3. High-performance ball-milled SiOx anodes for lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Zhang, Junying; Zhang, Chunqian; Liu, Zhi; Zheng, Jun; Zuo, Yuhua; Xue, Chunlai; Li, Chuanbo; Cheng, Buwen

    2017-01-01

    High-performance SiOx was scalable synthesized by means of simple high-energy ball-milling method, and used as anode materials for lithium ion batteries. The electrochemical performance of SiOx electrode after high-energy ball-milling is improved effectively compared to raw SiOx. That is benefit for the reduced size of SiOx powder. By changing the species of conductive agents, improved cyclic performance and excellent rate capability were achieved. Under galvanostatic mode with current density of 0.3 A/g, SiOx electrode after high-energy ball-milling with optimized conductive agents delivers a reversible capacity of 1416.8 mAh/g with coulombic efficiency as high as 99.8% and capacity retention of 83.6% (1184.8 mAh/g) even after 100 cycles. The approach is simple and can be adopted for large scale production of high performance SiOx anode materials.

  4. Scalable exfoliation process for highly soluble boron nitride nanoplatelets by hydroxide-assisted ball milling.

    PubMed

    Lee, Dongju; Lee, Bin; Park, Kwang Hyun; Ryu, Ho Jin; Jeon, Seokwoo; Hong, Soon Hyung

    2015-02-11

    The scalable preparation of two-dimensional hexagonal boron nitride (h-BN) is essential for practical applications. Despite intense research in this area, high-yield production of two-dimensional h-BN with large-size and high solubility remains a key challenge. In the present work, we propose a scalable exfoliation process for hydroxyl-functionalized BN nanoplatelets (OH-BNNPs) by a simple ball milling of BN powders in the presence of sodium hydroxide via the synergetic effect of chemical peeling and mechanical shear forces. The hydroxide-assisted ball milling process results in relatively large flakes with an average size of 1.5 μm with little damage to the in-plane structure of the OH-BNNP and high yields of 18%. The resultant OH-BNNP samples can be redispersed in various solvents and form stable dispersions that can be used for multiple purposes. The incorporation of the BNNPs into the polyethylene matrix effectively enhanced the barrier properties of the polyethylene due to increased tortuosity of the diffusion path of the gas molecules. Hydroxide-assisted ball milling process can thus provide simple and efficient approaches to scalable preparation of large-size and highly soluble BNNPs. Moreover, this exfoliation process is not only easily scalable but also applicable to other layered materials.

  5. Effect of Initial Aluminum Alloy Particle Size on the Damage of Carbon Nanotubes during Ball Milling

    PubMed Central

    Zhu, Xian; Zhao, Yu Guang; Wu, Min; Wang, Hui Yuan; Jiang, Qi Chuan

    2016-01-01

    Damage to carbon nanotubes (CNTs) during the fabrication process of CNT reinforced composites has great influence on their mechanical properties. In this study, the 2014 Al with powder sizes of 20, 9 and 5 μm was selected to study the effect of initial particle size on the damage to carbon nanotubes (CNTs) during ball milling. The result shows that for CNTs in the ball milled CNT/Al (with powder size of 20 and 9 μm) mixtures, the intensity ratio of the D band and the G band (ID/IG) first increased and then reached a plateau, mainly because most of the CNTs are embedded, to a certain extent, in the aluminum powder after milling, which could protect the CNTs from damage during further milling. While for CNTs in the ball milled CNT/Al (with powder size of 5 μm) mixture, the ID/IG ratio continues to climb from 1.31 to 2.33 with time, indicating continuous damage to the CNTs occurs during the milling. Differential scanning calorimetry (DSC) analysis demonstrates that the chemical instability increased with an increase in the damage level of CNTs, resulting in the formation of aluminum carbide (Al4C3) at a lower temperature before the melting of aluminum, which is detrimental to their mechanical properties. PMID:28773302

  6. Effect of Initial Aluminum Alloy Particle Size on the Damage of Carbon Nanotubes during Ball Milling.

    PubMed

    Zhu, Xian; Zhao, Yu Guang; Wu, Min; Wang, Hui Yuan; Jiang, Qi Chuan

    2016-03-08

    Damage to carbon nanotubes (CNTs) during the fabrication process of CNT reinforced composites has great influence on their mechanical properties. In this study, the 2014 Al with powder sizes of 20, 9 and 5 μm was selected to study the effect of initial particle size on the damage to carbon nanotubes (CNTs) during ball milling. The result shows that for CNTs in the ball milled CNT/Al (with powder size of 20 and 9 μm) mixtures, the intensity ratio of the D band and the G band (ID/IG) first increased and then reached a plateau, mainly because most of the CNTs are embedded, to a certain extent, in the aluminum powder after milling, which could protect the CNTs from damage during further milling. While for CNTs in the ball milled CNT/Al (with powder size of 5 μm) mixture, the ID/IG ratio continues to climb from 1.31 to 2.33 with time, indicating continuous damage to the CNTs occurs during the milling. Differential scanning calorimetry (DSC) analysis demonstrates that the chemical instability increased with an increase in the damage level of CNTs, resulting in the formation of aluminum carbide (Al₄C₃) at a lower temperature before the melting of aluminum, which is detrimental to their mechanical properties.

  7. Efficient dehalogenation of automobile shredder residue in NaOH/ethylene glycol using a ball mill.

    PubMed

    Kameda, Tomohito; Fukuda, Yuuzou; Park, Kye-Sung; Grause, Guido; Yoshioka, Toshiaki

    2009-01-01

    We investigated the effectiveness of sodium hydroxide/ethylene glycol (NaOH/EG) for dehalogenation of automobile shredder residue (ASR) using a ball mill. Efficient dehalogenation was achieved at atmospheric pressure by combining the use of EG (196 degrees C b.p.) as a replacement solvent for NaOH with ball milling, which improved contact between ASR and OH(-) in solution. Moderate NaOH concentrations and increased ball mill rotation speeds produced high dechlorination that was not significantly affected by the weight ratio of ASR to EG. NaOH/EG dechlorination increased with temperature with an apparent activation energy of 50 kJ mol(-1) confirming that the reaction proceeded under chemical reaction control. The modified shrinking-core model was appropriate to explain the dechlorination process. Low chloro levels in our NaOH/EG-treated ASR suggested that this material could be used for feedstock recycling and the wet process may be applicable for dehalogenation of other important waste streams.

  8. Microstructure and Physical Properties of Tb2TiO5 Neutron Absorber Synthesized by Ball Milling and Sintering

    NASA Astrophysics Data System (ADS)

    Huang, Jinghua; Ran, Guang; Liu, Tengjiao; Shen, Qiang; Li, Ning

    2016-10-01

    Tb2TiO5 neutron absorber was synthesized by ball milling and sintering. Microstructure character of ball-milled Tb4O7-17.605%TiO2 (mass fraction, %) powders and sintered bulks was analyzed using XRD, SEM and TEM. The microhardness, coefficient of thermal expansion and thermal conductivity of sintered bulks were measured. The experiment results showed that the nanocrystalline solid solution was obtained during ball milling. After 96 h of ball milling, TiO2 was completely solved in Tb4O7 and the crystal size of Tb4O7 was up to 37 nm. The bulk materials prepared by cold isostatic pressing were sintered at 1300 °C. Tb2TiO5 bulks with an orthorhombic structure were obtained. The microhardness of sintered bulks, as well as the thermal conductivity, increased firstly with increasing ball milling time and then decreased. The coefficient of thermal expansion decreased initially and then increased with increasing ball milling time. For the sintered bulk with powder milled for 48 h, the highest values of both microhardness and thermal conductivity were observed, whereas the lowest coefficient of thermal expansion was exhibited. In addition, with increasing testing temperature, the thermal conductivity of sintered bulks initially fell and then rebounded while an opposite trend was found in the coefficient of thermal expansion.

  9. Transformations in oxides induced by high-energy ball-milling.

    PubMed

    Šepelák, Vladimir; Bégin-Colin, Sylvie; Le Caër, Gérard

    2012-10-21

    This paper, by no means exhaustive, focuses on high-energy ball-milling of oxides, on their mechanically induced changes and on the consequences of such changes on their physical and chemical properties. High-energy ball-milling offers a fortunate combination of technical simplicity and of complexity both of physical mechanisms which act during milling and of mechanosynthesized materials. Its basic interest, which stems from the large diversity of routes it offers to prepare oxides either directly or indirectly, is illustrated with various families of oxides. The direct path is to be favoured when as-milled oxides are of interest per se because of their nanocrystalline characteristics, their defects or their modified structures which result from mechanically driven phase transformations. The indirect path consists of a sequence of steps starting with mechanically activated oxides which may be subsequently just annealed or submitted to a combination of thermal treatments, with the possible occurrence of various chemical reactions, to prepare the sought-after materials with potential gains in processing temperatures and times. High energy ball-milling of oxides is more and more currently used to activate powders and to prepare nano-oxides at moderate temperatures. The interest of an activation step is well illustrated by the broad development of doped titania powders, synthesized by heat treatment of pre-ground reactants, for photocatalytic applications or to develop antibacterial materials. Another important class of applications of high-energy ball-milling is the formation of composites. It is exemplified here with the case of oxide-dispersed strengthened alloys whose properties are considerably improved by a dispersion of ultra-stable nanosized oxides whose formation mechanisms were recently described. The basic understanding of the mechanisms by which oxides or oxide mixtures evolve by high-energy ball-milling appears to be less advanced than it is for metallic

  10. Extensive dry ball milling of wheat and rye bran leads to in situ production of arabinoxylan oligosaccharides through nanoscale fragmentation.

    PubMed

    Van Craeyveld, Valerie; Holopainen, Ulla; Selinheimo, Emilia; Poutanen, Kaisa; Delcour, Jan A; Courtin, Christophe M

    2009-09-23

    This study investigated the potential of ball milling as a dry process for in situ production of arabinoxylan oligosaccharides (AXOS) in arabinoxylan (AX)-rich wheat and rye bran. An extensive lab-scale ball mill treatment (120 h, 50% jar volume capacity) increased the wheat bran water-extractable arabinoxylan (WE-AX) level from 4% (untreated bran) to 61% of the wheat bran AX. Extractable AX fragments had an arabinose/xylose ratio (A/X ratio) of 0.72 and a molecular mass (MM) of 15 kDa. Ball milling of rye bran gave rise to similar results, with the A/X ratio of the extractable AX being considerably lower (0.51). Optimization of the ball mill treatment by varying the degree of filling of the milling jar permitted us to obtain equally high WE-AX levels (>70%) in wheat and rye bran within a 24 h ball-milling period. Ball milling at optimal conditions (24 h, 16% jar volume capacity) yielded wheat bran AXOS, with an A/X ratio of 0.65 and a MM of 6 kDa. Ball milling (24 h, 50% jar volume capacity) of pericarp-enriched wheat bran increased the WE-AX level from 1% (untreated pericarp) to 63%. The extractable material had a high A/X ratio (0.97) and a low MM (5 kDa). Fluorescence microscopy revealed that the extensive ball mill treatment led to the almost complete disappearance of discernible tissue structures in the ball-milled material, indicating bran particle size reductions down to the nanoscale level. It further visualized the aggregation of the treated material. These results show that AXOS can be produced in situ from wheat or rye bran in a single-stage dry milling process, rendering a wet extraction step redundant. The higher A/X ratio of the obtained AXOS than of enzymically produced wheat bran-derived AXOS offers perspectives for the production of a wide range of AXOS structures. Moreover, ball milling makes upgrading of the low-value pericarp layer feasible.

  11. Local structure of ball-milled LaNi{sub 5} hydrogen storage material by Ni K-edge EXAFS

    SciTech Connect

    Joseph, B.; Iadecola, A.; Schiavo, B.; Cognigni, A.; Olivi, L.; D'Ali Staiti, G.; Saini, N.L.

    2010-07-15

    Local structure of the nanostructured LaNi{sub 5} hydrogen storage alloys, prepared by ball-milling, has been studied using Ni K-edge extended X-ray absorption fine structure spectroscopy. Results indicate that the ball-milling up to 100 h results in the production of nanoparticles characterized by large atomic disorder and slightly reduced unit-cell volume, compared to the bulk LaNi{sub 5}. High temperature annealing appears to help in partial recovery of atomic order in the ball-milled samples; however, long-time ball-milled samples retain large disorder even after the high temperature annealing. The results suggest that the large disorder and the reduced unit-cell volume might be causing a higher energy-barrier for the hydride-phase formation in the long time ball-milled LaNi{sub 5} powders. - Graphical Abstract: X-ray diffraction (XRD) pattern (left panel) and Fourier transforms of the Ni K-edge extended X-ray absorption fine structure (EXAFS) spectroscopy (right panel) of bulk LaNi{sub 5} hydrogen storage material (structure model is given in the middle) together with the same after 100 h ball-milling. Milled samples show a remarkable reduction intensity and broadening of the XRD peaks. Substantial damping of the amplitude and a slight shrinkage of the profile are observed in the EXAFS spectrum. These results indicate that the ball-milling up to 100 h results in the production of nanoparticles characterized by slightly reduced unit-cell volume and substantial atomic disorder compared to the bulk LaNi5. High temperature annealing appears to help in partial recovery of atomic order in the ball-milled samples; however, long-time ball-milled samples retain the disorder even after the high temperature annealing. The results suggest that the large disorder and the reduced unit-cell volume might be causing a higher energy-barrier for the hydride-phase formation in the long-time ball-milled LaNi{sub 5} powders.

  12. Ball Mill Synthesis of Bulk Quaternary Cu2ZnSnSe4 and Thermoelectric Studies

    NASA Astrophysics Data System (ADS)

    Tiwari, Kunal J.; Prem Kumar, D. S.; Mallik, Ramesh Chandra; Malar, P.

    2017-01-01

    In this work, quaternary chalcogenide Cu2ZnSnSe4 (CZTSe) was synthesized using a mechanochemical ball milling process and its thermoelectric properties were studied by electrical resistivity, Seebeck coefficient, and thermal conductivity measurements. The synthesis process comprises three steps viz., wet ball milling of the elemental precursors, vacuum annealing, and densification by hot pressing. The purpose of this is to evaluate the feasibility of introducing wet milling in place of vacuum melting in solid state synthesis for the reaction of starting elements. We report the structural characterization and thermoelectric studies conducted on samples that were milled at 300 rpm and 500 rpm. X-ray diffraction (XRD) analysis showed the existence of multiple phases in the as-milled samples, indicating the requirement for heat treatment. Therefore, the ball milled powders were cold pressed and vacuum annealed to eliminate the secondary phases. Annealed samples were hot pressed and made into dense pellets for further investigations. In addition to XRD, energy dispersive spectroscopy (EDS) studies were performed on hot pressed samples to study the composition. XRD and EDS studies confirm CZTSe phase formation along with ZnSe secondary phase. Electrical resistivity and Seebeck coefficient measurements were done on the hot pressed samples in the temperature range 340-670 K to understand the thermoelectric behaviour. Thermal conductivity was calculated from the specific heat capacity and thermal diffusivity values. The thermoelectric figure of merit zT values for samples milled at 300 rpm and 500 rpm are ˜0.15 and ˜0.16, respectively, at 630 K, which is in good agreement with the values reported for solid state synthesized compounds.

  13. An environmentally friendly ball milling process for recovery of valuable metals from e-waste scraps.

    PubMed

    Zhang, Zhi-Yuan; Zhang, Fu-Shen; Yao, TianQi

    2017-10-01

    The present study reports a mechanochemical (MC) process for effective recovery of copper (Cu) and precious metals (i.e. Pd and Ag) from e-waste scraps. Results indicated that the mixture of K2S2O8 and NaCl (abbreviated as K2S2O8/NaCl hereafter) was the most effective co-milling reagents in terms of high recovery rate. After co-milling with K2S2O8/NaCl, soluble metallic compounds were produced and consequently benefit the subsequent leaching process. 99.9% of Cu and 95.5% of Pd in the e-waste particles could be recovered in 0.5mol/L diluted HCl in 15min. Ag was concentrated in the leaching residue as AgCl and then recovered in 1mol/L NH3 solution. XRD and XPS analysis indicated that elemental metals in the raw materials were transformed into their corresponding oxidation state during ball milling process at low temperature, implying that solid-solid phase reactions is the reaction mechanism. Based on the results and thermodynamic parameters of the probable reactions, possible reaction pathways during ball milling were proposed. Suggestion on category of e-waste for ball milling process was put forward according to the experiment results. The designed metal recovery process of this study has the advantages of highly recovery rate and quick leaching speed. Thus, this study offers a promising and environmentally friendly method for recovering valuable metals from e-waste. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Improvement on ball-milling composite process of metal matrix micro-nanometer powder using nanosuspension as the precursor

    NASA Astrophysics Data System (ADS)

    Wang, Hongyu; Zhou, Jianzhong; Li, Xiangfeng; Shen, Qing; Cheng, Man

    2014-12-01

    The wet ball-milling preparation of metal matrix micro-nanometer powder using nanosuspension as the precursor can well solve the agglomeration of nanoscale component, but the micro-nanometer powder prepared by the method can hardly meet the requirement of powder feeding in laser cladding process and its composite effect is still not desirable enough. Aiming at the problem, the ball-milling composite process of metal matrix micro-nanometer powder using nanosuspension as the precursor was analyzed. It has been found that the morphological diversity of original micron powder is the main influencing factor of the deliverability and the composite effect of micro-nanometer powder. In addition, the deposition of the compounding powder in the bottom of ball-milling tank also has some negative influences on the composite effect. Accordingly, two improving measures namely the micron powder pretreatment with Ball Mill Reshaping + Screening and the additional stirring during ball-milling process are proposed and experimented. Results show that the micron powder pretreatment could significantly improve the composite effect and the deliverability of micro-nanometer powder, and the additional stirring could further improve the composite effect of micro-nanometer powder.

  15. Processing of nanostructured nickel by severe plastic deformation consolidation of ball-milled powder

    SciTech Connect

    Valiev, R.Z. |; Mishral, R.S.; Grozal, J.; Mukherjee, A.K.

    1996-05-01

    Severe plastic deformation consolidation process of the ball-milled powder has been able to produce fully dense nanocrystalline nickel with a grain size of {approximately}20 nm. The processed samples are characterized by very high elastic strains, very likely caused by a presence of high density of extrinsic grain boundary dislocations. The combined effect of the smallest nanoscale grain size in nickel, as obtained in this study, along with the effect of high elastic strains, resulted in the high level of hardness and also the lower experimentally measured density of these severe plastic deformation consolidation samples.

  16. Parametric evaluation of ball milling of SiC in water

    NASA Technical Reports Server (NTRS)

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

    1985-01-01

    A statistically designed experiment was conducted to determine optimum conditions for ball milling alpha-SiC in water. The influence of pH adjustment, volume percent solids loading, and mill rotational speed on grinding effectiveness was examined. An equation defining the effect of those milling variables on specific surface area was obtained. The volume percent solids loading of the slurry had the greatest influence on the grinding effectiveness in terms of increase in specific surface area. As grinding effectiveness improved, mill and media wear also increased. Contamination was minimized by use of sintered alpha-SiC milling hardware.

  17. Nanomechanical Behavior of Multi-Walled Carbon Nanotubes Particulate Reinforced Aluminum Nanocomposites Prepared by Ball Milling

    PubMed Central

    Ostovan, Farhad; Matori, Khamirul Amin; Toozandehjani, Meysam; Oskoueian, Arshin; Yusoff, Hamdan Mohamed; Yunus, Robiah; Mohamed Ariff, Azmah Hanim

    2016-01-01

    The nanomechanical properties of carbon nanotubes particulate-reinforced aluminum matrix nanocomposites (Al-CNTs) have been characterized using nanoindentation. Bulk nanocomposite specimens containing 2 wt % multiwalled CNTs (MWCNTs) were synthesized by a combination of ball milling and powder metallurgy route. It has been tried to understand the correlation between microstructural evolution particularly carbon nanotubes (CNTs) dispersion during milling and mechanical properties of Al-2 wt % nanocomposites. Maximum enhancement of +23% and +44% has been found in Young’s modulus and hardness respectively, owing to well homogenous dispersion of CNTs within the aluminum matrix at longer milling time. PMID:28773261

  18. Parametric evaluation of ball milling of SiC in water

    NASA Technical Reports Server (NTRS)

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

    1985-01-01

    A statistically designed experiment was conducted to determine optimum conditions for ball milling alpha-SiC in water. The influence of pH adjustment, volume percent solids loading, and mill rotational speed on grinding effectiveness was examined. An equation defining the effect of those milling variables on specific surface area was obtained. The volume percent solids loading of the slurry had the greatest influence on the grinding effectiveness in terms of increase in specific surface area. As grinding effectiveness improved, mill and media wear also increased. Contamination was minimized by use of sintered alpha-SiC milling hardware.

  19. Ball Milling Assisted Solvent and Catalyst Free Synthesis of Benzimidazoles and Their Derivatives.

    PubMed

    El-Sayed, Taghreed H; Aboelnaga, Asmaa; Hagar, Mohamed

    2016-08-24

    Benzoic acid and o-phenylenediamine efficiently reacted under the green solvent-free Ball Milling method. Several reaction parameters were investigated such as rotation frequency; milling balls weight and milling time. The optimum reaction condition was milling with 56.6 g weight of balls at 20 Hz frequency for one hour milling time. The study was extended for synthesis of a series of benzimidazol-2-one or benzimidazol-2-thione using different aldehydes; carboxylic acids; urea; thiourea or ammonium thiocyanate with o-phenylenediamine. Moreover; the alkylation of benzimidazolone or benzimidazolthione using ethyl chloroacetate was also studied.

  20. Mechanochemical synthesis of PbF2 by high energy ball milling

    NASA Astrophysics Data System (ADS)

    Heise, M.; Scholz, G.; Kemnitz, E.

    2017-10-01

    Lead(II)-fluoride was successfully prepared by high energy ball milling and for comparison by classical thermal solid state chemical reaction. The influence of different starting materials, fluorinating agents and synthesis methods on the formation of the orthorhombic α-phase and the cubic β-phase was investigated. XRD analysis provided insight of which phase was formed under varying synthesis conditions. 19F and 207Pb MAS NMR measurements delivered an even further insight into the local structures. Additional simulations of the 19F spectra were performed to identify the 19F-207Pb coupling constants of the four-fold coordinated fluorine sites in both phases.

  1. Generation of drugs coated iron nanoparticles through high energy ball milling

    SciTech Connect

    Radhika Devi, A.; Murty, B. S.; Chelvane, J. A.; Prabhakar, P. K.; Padma Priya, P. V.; Doble, Mukesh

    2014-03-28

    The iron nanoparticles coated with oleic acid and drugs such as folic acid/Amoxicillin were synthesized by high energy ball milling and characterized by X-ray diffraction, Transmission electron microscope, zeta potential, dynamic light scattering, Fourier Transform Infra red (FT-IR) measurements, and thermo gravimetric analysis (TGA). FT-IR and TGA measurements show good adsorption of drugs on oleic acid coated nanoparticles. Magnetic measurements indicate that saturation magnetization is larger for amoxicillin coated particles compared to folic acid coated particles. The biocompatibility of the magnetic nanoparticles prepared was evaluated by in vitro cytotoxicity assay using L929 cells as model cells.

  2. Nucleophilic displacement reactions of 5′-derivatised nucleosides in a vibration ball mill

    PubMed Central

    Eguaogie, Olga; Conlon, Patrick F; Ravalico, Francesco; Sweet, Jamie S T; Elder, Thomas B; Conway, Louis P; Lennon, Marc E; Hodgson, David R W

    2017-01-01

    Vibration ball-milling in a zirconia-lined vessel afforded clean and quantitative nucleophilic displacement reactions between 4-methoxybenzylthiolate salts and nucleoside 5′-halides or 5′-tosylates in five to 60 minutes. Under these conditions, commonly-encountered nucleoside cyclisation byproducts (especially of purine nucleosides) were not observed. Liquid-assisted grinding of the same 5'-iodide and 5′-tosylate substrates with potassium selenocyanate in the presence of DMF produced the corresponding 5′-selenocyanates in variable yields over the course of between one and eleven hours thereby avoiding the preparation and use of hygroscopic tetrabutylammonium salts. PMID:28179952

  3. Generation of drugs coated iron nanoparticles through high energy ball milling

    NASA Astrophysics Data System (ADS)

    Radhika Devi, A.; Chelvane, J. A.; Prabhakar, P. K.; Padma Priya, P. V.; Doble, Mukesh; Murty, B. S.

    2014-03-01

    The iron nanoparticles coated with oleic acid and drugs such as folic acid/Amoxicillin were synthesized by high energy ball milling and characterized by X-ray diffraction, Transmission electron microscope, zeta potential, dynamic light scattering, Fourier Transform Infra red (FT-IR) measurements, and thermo gravimetric analysis (TGA). FT-IR and TGA measurements show good adsorption of drugs on oleic acid coated nanoparticles. Magnetic measurements indicate that saturation magnetization is larger for amoxicillin coated particles compared to folic acid coated particles. The biocompatibility of the magnetic nanoparticles prepared was evaluated by in vitro cytotoxicity assay using L929 cells as model cells.

  4. Enhanced Oxidative Reactivity for Anthracite Coal via a Reactive Ball Milling Pretreatment Step

    SciTech Connect

    Angela D. Lueking; Apurba Sakti; Dania Alvarez-Fonseca; Nichole Wonderling

    2009-09-15

    Reactive ball milling in a cyclohexene solvent significantly increases the oxidative reactivity of an anthracite coal, due to the combined effects of particle size reduction, metal introduction, introduction of volatile matter, and changes in carbon structure. Metals introduced during milling can be easily removed via a subsequent demineralization process, and the increased reactivity is retained. Solvent addition alters the morphological changes that occur during pyrolysis and leads to a char with significantly increased reactivity. When the solvent is omitted, similar effects are seen for the milled product, but a significant fraction of the char is resistant to oxidation. 33 refs., 3 figs., 1 tab.

  5. Characterization of High-Energy Ball-Milled and Hot-Pressed Nanocrystalline Tantalum

    NASA Astrophysics Data System (ADS)

    Jakubowicz, J.; Adamek, G.; Sopata, M.

    2017-06-01

    The paper shows a comparison of nanocrystalline and microcrystalline tantalum sinters. The nanocrystalline tantalum was made using high-energy ball milling. The sinters were made using hot pressing with high frequency induction heating. The structure and microstructure of the powders and sinters were investigated. After 48 hour milling, the microcrystalline tantalum transformed into nanocrystalline powder. The hot pressing resulted in a formation of bulk tantalum with ultrafine grains and hardness as high as 1067 HV. The nanostructure supports the densification process at lower sintering temperature in comparison to microcrystalline tantalum. The average crystallite size in nanocrystalline bulk materials reached 170 nm.

  6. Magnetic hardening of high-energy ball-milled nanocrystalline LaMn 2Si 2

    NASA Astrophysics Data System (ADS)

    Elmali, Ayhan; Tekerek, Simsek; Dincer, Ilker; Elerman, Yalcin; Theissmann, Ralf; Ehrenberg, Helmut; Fuess, Hartmut

    Nanocrystalline LaMn 2Si 2 powders have been obtained by high-energy ball milling for 30 min from bulk alloys. After milling a high coercivity about 6 kOe is observed at 10 K in contrast to neglectable coercivity for the bulk LaMn 2Si 2 at 5 K. The average grain size of the optimum particles which is obtained from X-ray diffraction pattern and HRTEM picture is about 20 nm. The magnetic hardening is observed for the nanocrystalline LaMn 2Si 2, reflected in the coercivity field strength of 6 kOe at 10 K.

  7. Effect of expansion temperature of expandable graphite on microstructure evolution of expanded graphite during high-energy ball-milling

    SciTech Connect

    Yue Xueqing; Li Liang; Zhang Ruijun; Zhang Fucheng

    2009-12-15

    Two expanded graphites (EG), marked as EG-1 and EG-2, were prepared by rapid heating of expandable graphite to 600 and 1000 deg. C, respectively, and ball milled in a high-energy mill (planetary-type) under air atmosphere. The microstructure evolution of the ball-milled samples was characterized by X-ray diffraction (XRD) and high resolution transmission electron microscopy (HRTEM). XRD analysis shows that the evolution degree of the average crystallite thickness along the c-axis (L{sub c}) of EG-2 is lower than that of EG-1 during the milling process. From the HRTEM images of the samples after 100 h ball-milling, slightly curved graphene planes can be frequently observed both in the two EGs, however, EG-1 and EG-2 exhibit sharply curved graphene planes and smoothly curved graphene planes with high bending angles, respectively.

  8. Strong textured SmCo5 nanoflakes with ultrahigh coercivity prepared by multistep (three steps) surfactant-assisted ball milling.

    PubMed

    Zuo, Wen-Liang; Zhao, Xin; Xiong, Jie-Fu; Zhang, Ming; Zhao, Tong-Yun; Hu, Feng-Xia; Sun, Ji-Rong; Shen, Bao-Gen

    2015-08-14

    The high coercivity of 26.2 kOe for SmCo5 nanoflakes are obtained by multistep (three steps) surfactant-assisted ball milling. The magnetic properties, phase structure and morphology are studied by VSM, XRD and SEM, respectively. The results demonstrate that the three step ball-milling can keep more complete crystallinity (relatively less defects) during the process of milling compared with one step high energy ball-milling, which enhances the texture degree and coercivity. In addition, the mechanism of coercivity are also studied by the temperature dependence of demagnetization curves for aligned SmCo5 nanoflakes/resin composite, the result indicates that the magnetization reversal could be controlled by co-existed mechanisms of pinning and nucleation.

  9. Bioethanol production from ball milled bagasse using an on-site produced fungal enzyme cocktail and xylose-fermenting Pichia stipitis.

    PubMed

    Buaban, Benchaporn; Inoue, Hiroyuki; Yano, Shinichi; Tanapongpipat, Sutipa; Ruanglek, Vasimon; Champreda, Verawat; Pichyangkura, Rath; Rengpipat, Sirirat; Eurwilaichitr, Lily

    2010-07-01

    Sugarcane bagasse is one of the most promising agricultural by-products for conversion to biofuels. Here, ethanol fermentation from bagasse has been achieved using an integrated process combining mechanical pretreatment by ball milling, with enzymatic hydrolysis and fermentation. Ball milling for 2 h was sufficient for nearly complete cellulose structural transformation to an accessible amorphous form. The pretreated cellulosic residues were hydrolyzed by a crude enzyme preparation from Penicillium chrysogenum BCC4504 containing cellulase activity combined with Aspergillus flavus BCC7179 preparation containing complementary beta-glucosidase activity. Saccharification yields of 84.0% and 70.4% for glucose and xylose, respectively, were obtained after hydrolysis at 45 degrees C, pH 5 for 72 h, which were slightly higher than those obtained with a commercial enzyme mixture containing Acremonium cellulase and Optimash BG. A high conversion yield of undetoxified pretreated bagasse (5%, w/v) hydrolysate to ethanol was attained by separate hydrolysis and fermentation processes using Pichia stipitis BCC15191, at pH 5.5, 30 degrees C for 24 h resulting in an ethanol concentration of 8.4 g/l, corresponding to a conversion yield of 0.29 g ethanol/g available fermentable sugars. Comparable ethanol conversion efficiency was obtained by a simultaneous saccharification and fermentation process which led to production of 8.0 g/l ethanol after 72 h fermentation under the same conditions. This study thus demonstrated the potential use of a simple integrated process with minimal environmental impact with the use of promising alternative on-site enzymes and yeast for the production of ethanol from this potent lignocellulosic biomass.

  10. Defect induced electronic states and magnetism in ball-milled graphite.

    PubMed

    Milev, Adriyan; Dissanayake, D M A S; Kannangara, G S K; Kumarasinghe, A R

    2013-10-14

    The electronic structure and magnetism of nanocrystalline graphite prepared by ball milling of graphite in an inert atmosphere have been investigated using valence band spectroscopy (VB), core level near-edge X-ray absorption fine structure (NEXAFS) spectroscopy and magnetic measurements as a function of the milling time. The NEXAFS spectroscopy of graphite milled for 30 hours shows simultaneous evolution of new states at ~284.0 eV and at ~290.5 eV superimposed upon the characteristic transitions at 285.4 eV and 291.6 eV, respectively. The modulation of the density of states is explained by evolution of discontinuities within the sheets and along the fracture lines in the milled graphite. The magnetic measurements in the temperature interval 2-300-2 K at constant magnetic field strength show a correlation between magnetic properties and evolution of the new electronic states. With the reduction of the crystallite sizes of the graphite fragments, the milled material progressively changes its magnetic properties from diamagnetic to paramagnetic with contributions from both Pauli and Curie paramagnetism due to the evolution of new states at ~284 and ~290.5 eV, respectively. These results indicate that the magnetic behaviour of ball-milled graphite can be manipulated by changing the milling conditions.

  11. Influence of Iron Oxide Particles on the Strength of Ball-Milled Iron

    SciTech Connect

    Lesuer, D R; Syn, C K; Sherby, O D

    2005-12-07

    Detailed microstructural and mechanical property studies of ball-milled iron, in the powder and consolidated states, are reviewed and assessed. The analyses cover three and one-half orders of magnitude of grain size (from 6 nm to 20 mm) and focus on the influence of oxide particles on the strength. The study includes the early work of Koch and Yang, Kimura and Takaki and continues with the more recent work of Umemoto et al and Belyakov, Sakai et al. It is shown that the major contributors to strength are the nanooxide particles. These particles are created by adiabatic shear banding during ball-milling leading to a bimodal distribution of particles. The predicted strength from particles, {sigma}{sub p}, is given by {sigma}{sub p} = B {center_dot} (D*{sub S}){sup -1/2} where D*{sub S} is the surface-to-surface interparticle spacing, and B = 395 MPa {center_dot} {micro}m{sup -1/2}. A model is proposed that accounts for the influence of the bimodal particle size distribution on strength.

  12. Microwave absorption properties of FeSi flaky particles prepared via a ball-milling process

    NASA Astrophysics Data System (ADS)

    Liu, Chao; Yuan, Yong; Jiang, Jian-tang; Gong, Yuan-xun; Zhen, Liang

    2015-12-01

    Flaky FeSi alloy particles with different aspect ratio were produced via ball-milling and a subsequent annealing. The microstructure and the morphology of the particles were examined by XRD and SEM. The dc resistivity, the static magnetization properties and electromagnetic properties were measured. Particles with high aspect ratio were found possess high permittivity and permeability. On the other hand, the variation of grain size and defects density was found influence the permittivity and permeability. High specific area was believed contribute to the intense dielectric loss and the high shape magnetic anisotropy lead to high permeability in the target band. Increased electromagnetic parameters compel the absorption peak's shift to lower frequency. Coating using flaky FeSi particles milled for 12 h as fillers presented a reflection loss of -10 dB at 2 GHz and a matching thickness of 1.88 mm. The flaky FeSi alloy particles prepared through ball-milling and annealing can be promising candidates for EMA application at 1-4 GHz band.

  13. Microstructural Characterization of Calcite-Based Powder Materials Prepared by Planetary Ball Milling

    PubMed Central

    Tsai, Wen-Tien

    2013-01-01

    In this work, a planetary ball milling was used to modify the surface properties of calcite-based material from waste oyster shell under the rotational speed of 200–600 rpm, grinding time of 5–180 min and sample mass of 1–10 g. The milling significantly changed the microstructural properties of the calcite-based minerals (i.e., surface area, pore volume, true density, and porosity). The surface characterization of the resulting powder should be macroporous and/or nonporous based on the nitrogen adsorption/desorption isotherms. Under the optimal conditions at the rotational speed of 400 rpm, grinding time of 30 min and sample mass of 5 g, the resulting calcite-based powder had larger specific surface area (i.e., 10.64 m2·g−1) than the starting material (i.e., 4.05 m2·g−1). This finding was also consistent with the measurement of laser-diffraction (i.e., 9.7 vs. 15.0 μm of mean diameter). In addition, the results from the scanning electron microscope (SEM) observation indicated that surface roughness can be enhanced as particle size decreases as a result of particle-particle attrition. Thus, grinding the aquacultural bioresource by a high-energy ball milling can create the fine materials, which may be applied in the fields of inorganic minerals like aggregate and construction material. PMID:28811439

  14. Dissipation mechanisms in polycrystalline YBCO prepared by sintering of ball-milled precursor powder

    NASA Astrophysics Data System (ADS)

    Hannachi, E.; Ben Salem, M. K.; Slimani, Y.; Hamrita, A.; Zouaoui, M.; Ben Azzouz, F.; Ben Salem, M.

    2013-12-01

    Magnetoresistivity (ρ(T,H)) measurements of polycrystalline YBa2Cu3Oy (Y-123) and YBa2Cu3Oy embedded with nanoparticles of Y-deficient Y-123, generated by the planetary ball milling, have been compared and analyzed by the Ambegaokar and Halperin phase slip model (AH) and thermally activated flux creep (TAFC). Phase analysis by X-ray diffraction (XRD), granular structure examination by scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDXS), were carried out. SEM analyses show that nanoparticles of Y-deficient Y-123, generated by ball milling, are embedded in the superconducting matrix. The broadening of the resistive transition under magnetic field is found to possess two distinct regions, which suggests that dissipation phenomenon in milled and unmilled samples is caused by two mechanisms: the order parameter fluctuations and the vortex-dynamics separated by a crossover temperature T. The critical current Jc(0) at zero temperature in the grain boundaries decreases as a power law, H, which is an indication of the sensitivity of a single junction between the superconducting grains to the applied magnetic field. Jc(0) of the milled material is higher than the one of the unmilled and the activation energies of vortex flux motion U(H) behavior in the applied magnetic field is enhanced by the presence of the nanoparticles embedded in the matrix.

  15. Experimental and Modeling Study of the Regular Polygon Angle-spiral Liner in Ball Mills

    NASA Astrophysics Data System (ADS)

    Sun, Yi; Liang, Man; Jin, Xiaohang; Ji, Pengpeng; Shan, Jihong

    2017-03-01

    Load behavior is one of the most critical factors affecting mills' energy consumption and grinding efficiency, and is greatly affected by the liner profiles. Generally, as liner profiles vary, the ball mill performances are extremely different. In order to study the performance of the ball mill with regular polygon angle-spiral liners(RPASLs), experimental and numerical studies on three types of RPASLs, including regular quadrilateral, pentagonal and hexagonal, are carried out. For the fine product of desired size, two critical parameters are analyzed: the energy input to the mill per unit mass of the fine product, E^{*}, and the rate of production of the fine product, F^{*}. Results show that the optimal structure of RPASLs is Quadrilateral ASL with an assembled angle of 50°. Under this condition, the specific energy consumption E^{*} has the minimum value of 303 J per fine product and the production rate F^{*} has the maximum value of 0.323. The production rate F^{*} in the experimental result is consistent with the specific collision energy intensity to total collision energy intensity ratio E_s/E_t in the simulation. The relations between the production rate F^{*} and the specific energy consumption E^{*} with collision energy intensity E_s and E_t are obtained. The simulation result reveals the essential reason for the experimental phenomenon and correlates the mill performance parameter to the collision energy between balls, which could guide the practical application for Quadrilateral ASL.

  16. Ball mill assisted rapid mechanochemical extraction method for natural products from plants.

    PubMed

    Wang, Man; Bi, Wentao; Huang, Xiaohua; Chen, David Da Yong

    2016-06-03

    A ball mill assisted mechanochemical extraction method was developed to extract compounds of natural product (NP) from plant using ionic liquid (IL). A small volume ball mill, also known as PastPrep(®) Homogenizer, which is often used for high-speed lysis of biological samples and for other applications, was used to dramatically increase the speed, completeness and reproducibility of the extraction process at room temperature to preserve the chemical integrity of the extracted compounds. In this study, tanshinones were selected as target compounds to evaluate the performance of this extraction method. Factors affecting the extraction efficiency, such as the duration, IL concentration and solid/liquid ratio were systematically optimized using the response surface methodology. Under the optimized conditions, the described method was more efficient and much faster than the conventional extraction methods such as methanol based ultrasound assisted extraction (UAE) and heat reflux extraction (HRE) that consumes a lot more organic solvent. In addition, the natural products of interest were enriched by anion metathesis of ionic liquids, combining extraction and preconcentration in the same process. The extractant was analyzed by HPLC and LC-MS. The reproducibility (RSD, n=5), correlation coefficient (r(2)) of the calibration curve, and the limit of detection, were determined to be in the range of 4.7-5.2%, 0.9992-0.9995, and 20-51ng/mL, respectively.

  17. Experimental and Modeling Study of the Regular Polygon Angle-spiral Liner in Ball Mills

    NASA Astrophysics Data System (ADS)

    Sun, Yi; Liang, Man; Jin, Xiaohang; Ji, Pengpeng; Shan, Jihong

    2017-03-01

    Load behavior is one of the most critical factors affecting mills' energy consumption and grinding efficiency, and is greatly affected by the liner profiles. Generally, as liner profiles vary, the ball mill performances are extremely different. In order to study the performance of the ball mill with regular polygon angle-spiral liners(RPASLs), experimental and numerical studies on three types of RPASLs, including regular quadrilateral, pentagonal and hexagonal, are carried out. For the fine product of desired size, two critical parameters are analyzed: the energy input to the mill per unit mass of the fine product, E^{*} , and the rate of production of the fine product, F^{*} . Results show that the optimal structure of RPASLs is Quadrilateral ASL with an assembled angle of 50°. Under this condition, the specific energy consumption E^{*} has the minimum value of 303 J per fine product and the production rate F^{*} has the maximum value of 0.323. The production rate F^{*} in the experimental result is consistent with the specific collision energy intensity to total collision energy intensity ratio E_s/E_t in the simulation. The relations between the production rate F^{*} and the specific energy consumption E^{*} with collision energy intensity E_s and E_t are obtained. The simulation result reveals the essential reason for the experimental phenomenon and correlates the mill performance parameter to the collision energy between balls, which could guide the practical application for Quadrilateral ASL.

  18. Characterization of ball-milled carbon nanotube dispersed aluminum mixed powders

    NASA Astrophysics Data System (ADS)

    Maleque, M. A.; Abdullah, U.; Yaacob, I.; Ali, Y.

    2016-04-01

    Currently, carbon nanotube (CNT) is attracting much interest as fibrous materials for reinforcing aluminum matrix composites due to unique properties, such as high strength, elastic modulus, flexibility and high aspect ratios. However, the quality of the dispersion is the major concerning factor which determines the homogeneity of the enhanced mechanical and tribological properties of the composite. This work study and characterized carbon nanotube dispersion in ballmilled CNT-aluminum mixed powders with four different formulations such as 1, 1.5, 2 and 2.5 wt% CNT under high energy planetary ball milling operations. The ball milling was performed for two hours at constant milling speed of 250 rpm under controlled atmosphere. The characterization is performed using FESEM and EDX analyzer for mapping, elemental and line analysis. The experimental results showed homogeneous dispersion of CNTs in aluminum matrix. The composite mixture showed similar pattern from mapping, elemental and line analysis. Identification of only two peaks proved that controlled atmosphere during milling prevented the formation of inter metallic compounds such as aluminum carbide in the composite mixture. Therefore, this CNT-A1 composite powder mixture can be used for new nano-composite development without any agglomeration problem.

  19. Homogeneity of ball milled ceramic powders: Effect of jar shape and milling conditions.

    PubMed

    Broseghini, M; D'Incau, M; Gelisio, L; Pugno, N M; Scardi, P

    2017-02-01

    This paper contains data and supporting information of and complementary to the research article entitled "Effect of jar shape on high-energy planetary ball milling efficiency: simulations and experiments" (Broseghini et al.,) [1]. Calcium fluoride (CaF2) was ground using two jars of different shape (cylindrical and half-moon) installed on a planetary ball-mill, exploring different operating conditions (jar-to-plate angular velocity ratio and milling time). Scanning Electron Microscopy (SEM) images and X-Ray Powder Diffraction data (XRPD) were collected to assess the effect of milling conditions on the end-product crystallite size. Due to the inhomogeneity of the end product, the Whole Powder Pattern Model (WPPM, (Scardi, 2008) [2]) analysis of XRPD data required the hypothesis of a bimodal distribution of sizes - respectively ground (fine fraction) and less-to-not ground (coarse fraction) - confirmed by SEM images and suggested by the previous literature (Abdellatief et al., 2013) [3,4]. Predominance of fine fraction clearly indicates optimal milling conditions.

  20. Effect of ball milling energy on rheological and thermal properties of amaranth flour.

    PubMed

    Roa, Diego F; Baeza, Rosa I; Tolaba, Marcela P

    2015-12-01

    Pearled amaranth grains obtained by abrasive milling were processed by planetary ball milling to produce amaranth flours. The influence of milling energy on rheological and thermal behavior of amaranth flour dispersions and stability during 24 h storage at 4 °C were investigated based on a factorial design. The rheological behavior of flour dispersions (4 % and 8 % w/v) was determined using a rotational viscometer, while gelatinization degree was determined by differential scanning calorimetry as a measure of structural changes.The power law model was found to be suitable in expressing the relationship between shear stress and shear rate. Flour dispersions showed a pseudoplastic behavior. However this character decreased with the storage being dependent on flour concentration and milling energy. A decrease of the consistency index and an increase of the flow behavior index were observed as a result of the increasing milling energy. Gelatinization enthalpy decrease showed the loss of crystalline structure due to ball milling. Amaranth flour dispersions presented increasing stability during storage. It was observed, that the stability changed with the concentration of amaranth flours.Thus, more stable dispersions were obtained as the flour concentration increased. The highly milled sample was the most stable sample during the storage.

  1. HRTEM and Nanoindentation Studies of Bulk WC Nanocrystalline Materials Prepared by Spark Plasma Sintering of Ball-Milled Powders

    NASA Astrophysics Data System (ADS)

    Sherif El-Eskandarany, M.; Al-Hazza, Abdulsalam; Al-Hajji, L. A.

    2016-11-01

    In the present work, mechanical milling technique using a high-energy ball mill was employed for preparing of nanoscaled WC grains powders with an average grain size of 7 nm in diameters of WC. The present study demonstrates a successful consolidation process achieved at 1250 °C for sintering of ball-milled WC powders into full dense bulk buttons (above 99.6%), using SPS technique. The as-consolidated WC bulk nanocrystalline buttons revealed high hardness value ( 24 GPa) with low elastic modulus ( 332 GPa). Moreover, they possessed a high fracture toughness (15 MPa m1/2) that has never been reported for pure WC.

  2. Investigation of the effect of intensive milling in a planetary ball mill on the thermal decomposition of basic nickel carbonate

    NASA Astrophysics Data System (ADS)

    Książek, K.; Wacke, S.; Górecki, T.; Górecki, Cz

    2011-04-01

    The kinetics of thermal decomposition of basic nickel carbonate NiCO3Ni·(OH)2·nH2O and the effect of intensive milling in a planetary ball mill on its parameters, have been investigated. The values of the reaction heat and of the activation energy of thermal decomposition have been determined. Investigations of the thermal decomposition of the products of ball milling of investigated compound revealed a distinct effect of milling on the reaction temperature and heat consumed during the thermal decomposition of investigated compound.

  3. HRTEM and Nanoindentation Studies of Bulk WC Nanocrystalline Materials Prepared by Spark Plasma Sintering of Ball-Milled Powders

    NASA Astrophysics Data System (ADS)

    Sherif El-Eskandarany, M.; Al-Hazza, Abdulsalam; Al-Hajji, L. A.

    2017-01-01

    In the present work, mechanical milling technique using a high-energy ball mill was employed for preparing of nanoscaled WC grains powders with an average grain size of 7 nm in diameters of WC. The present study demonstrates a successful consolidation process achieved at 1250 °C for sintering of ball-milled WC powders into full dense bulk buttons (above 99.6%), using SPS technique. The as-consolidated WC bulk nanocrystalline buttons revealed high hardness value ( 24 GPa) with low elastic modulus ( 332 GPa). Moreover, they possessed a high fracture toughness (15 MPa m1/2) that has never been reported for pure WC.

  4. Fabrication of lanthanum-doped thorium dioxide by high-energy ball milling and spark plasma sintering

    NASA Astrophysics Data System (ADS)

    Scott, Spencer M.; Yao, Tiankai; Lu, Fengyuan; Xin, Guoqing; Zhu, Weiguang; Lian, Jie

    2017-03-01

    High-energy ball milling was used to synthesize Th1-xLaxO2-0.5x (x = 0.09, 0.23) solid solutions, as well as improve the sinterability of ThO2 powders. Dense La-doped ThO2 pellets with theoretical density above 94% were consolidated by spark plasma sintering at temperatures above 1400 °C for 20 min, and the densification behavior and the non-equilibrium effects on phase and structure were investigated. A lattice contraction of the SPS-densified pellets occurred with increasing ball milling duration, and a secondary phase with increased La-content was observed in La-doped pellets. A dependence on the La-content and sintering duration for the onset of localized phase segregation has been proposed. The effects of high-energy ball milling, La-content, and phase formation on the thermal diffusivity were also studied for La-doped ThO2 pellets by laser flash measurement. Increasing La-content and high energy ball milling time decreases thermal diffusivity; while the sintering peak temperature and holding time beyond 1600 °C dramatically altered the temperature dependence of the thermal diffusivity beyond 600 °C.

  5. Characteristics and oil absorption in deep-fat fried batter prepared from ball-milled wheat flour.

    PubMed

    Thanatuksorn, Pariya; Kajiwara, Kazuhito; Suzuki, Toru

    2010-01-15

    The porous structure generated during frying influences oil absorption and textural qualities. The alteration in physical properties of wheat flour is suspected to affect the structure formation. The present study investigated the effect of physicochemical changes in wheat flour by the ball-milling process on structure formation and consequently oil absorption of a fried wheat flour batter model. Batter models containing 600 g kg(-1) moisture were made of 0-10 h ball-milled wheat flour and then fried in frying oil at 150 degrees C for 1-7 min. The samples made of milled flour possess larger pores and exhibit lower oil absorption than sample made of 0 h milled flour. The fracture force of a fried sample prepared from 5 and 10 h milled flour is lower than that of a sample prepared from 0 h milled flour. The decrease in glass transition temperature (T(g)) and melting temperature (T(m)) of milled flour affect the microstructure formation in the fried wheat flour batter. The microstructure is responsible for oil absorption and fracturability in fried food. The samples made of flour of longer ball-milling time have lower oil absorption and higher crispness. Ball-milling may be a tool to produce mechanically modified wheat flour which can reduce oil absorption for fried batter. Copyright (c) 2009 Society of Chemical Industry.

  6. One step conversion of wheat straw to sugars by simultaneous ball milling, mild acid, and fungus Penicillium simplicissimum treatment.

    PubMed

    Yuan, Li; Chen, Zhenhua; Zhu, Yonghua; Liu, Xuanming; Liao, Hongdong; Chen, Ding

    2012-05-01

    Wheat straw is one of the major lignocellulosic plant residues in many countries including China. An attractive alternative is the utilization of wheat straw for bioethanol production. This article mainly studies a simple one-step wet milling with Penicillium simplicissimum and weak acid to hydrolysis of wheat straw. The optimal condition for hydrolysis was ball milling 48 h in citrate solvent (pH = 4) with P. simplicissimum H5 at the speed of 500 rpm and the yield of sugar increased with increased milling time. Corresponding structure transformations before and after milling analyzed by X-ray diffraction, transmission Fourier transform infrared spectroscopy, and environmental scanning electron microscopy clearly indicated that this combined treatment could be attributed to the crystalline and chemical structure changes of cellulose in wheat straw during ball milling. This combined treatment of ball milling, mild acid, and fungus hydrolysis enabled the conversion of the wheat straw. Compared with traditional method of ball milling, this work showed a more simple, novel, and environmentally friendly way in mechanochemical treatment of wheat straw.

  7. Reaction between LiBH4 and MgH2 induced by high-energy ball milling

    NASA Astrophysics Data System (ADS)

    Ding, Zhao; Zhao, Xuzhe; Shaw, Leon L.

    2015-10-01

    Previous studies of ab initio density functional theory (DFT) calculations have predicted that reactions between LiBH4 and MgH2 can take place at temperature near 200 °C. However, such predictions have been shown to be inconsistent with many experiments. Herein, we have designed a novel process termed as ball milling with aerosol spraying (BMAS) to prove, for the first time, that the reaction between LiBH4 and MgH2 can indeed occur during ball milling at room temperature. Through this BMAS process we have demonstrated unambiguously the formation of MgB2 and LiH during ball milling of MgH2 while aerosol spraying of the LiBH4/THF solution. In this BMAS process, aerosol spraying of the LiBH4/THF solution leads to the formation of LiBH4 nanoparticles which decompose to form Li2B12H12. The Li2B12H12 formed then reacts with MgH2 in situ during ball milling to form MgB2 and LiH. The discovery made in this study has significant implications in making LiBH4 + MgH2 as a viable system for reversible hydrogen storage applications near ambient temperature in the future.

  8. Effect of ball-milling surfactants on the interface chemistry in hot-compacted SmCo5 magnets

    SciTech Connect

    Li, WF; Sepehri-Amin, H; Zheng, LY; Cui, BZ; Gabay, AM; Hono, K; Huang, WJ; Ni, C; Hadjipanayis, GC

    2012-11-01

    Anisotropic SmCo5 nanoflakes prepared by high-energy ball-milling with surfactants have great potential in applications for high-performance nanocomposite magnets. For such "nanocomposite" applications, the surface structure and chemistry of nanoflakes are crucial for achieving high coercivity. In this study, hot-pressed samples from anisotropic SmCo5 nanoflakes, ball-milled with different surfactants, oleic acid (OA) and oleylamine (OY), were investigated. Interface layers between the SmCo5 nanoflakes were found to consist of samarium oxides and a soft magnetic Co phase. These surface layers contribute to the degradation of hard magnetic performance, which is confirmed by scanning transmission electron microscopy-energy dispersive X-ray spectroscopy analysis of the cross-section of a single flake ball-milled with OA. Samples milled with OY show a much thinner interface layer in compacted samples, which means that the surface degradation during ball-milling with OY is much less than that with OA. The results show clearly that the choice of proper surfactant and the control of processing parameters are the key factors for improving the surface condition of the nanoflakes and the resulting hard magnetic properties. (C) 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  9. Substructure of Titanium Dioxide Agglomerates from Dry Ball-milling Experiments

    NASA Astrophysics Data System (ADS)

    Gesenhues, Ulrich

    1999-06-01

    The calciner discharge of TiO2 white pigments from the sulphate process is ground batchwise in a planetary ball mill, varying the energy of comminution between 0 and 5.1 times the earth's gravitational constant. Particle sizes and specific surfaces of the ground products reveal that the calciner discharge consists of aggregates of 430 nm diameter built from 160-210 nm TiO2 crystals. The contact area of a primary particle in an aggregate is about 15% of its surface. The success in comminution of aggregates as a function of grinding energy follows Kick's law. The theory by Rose and Weichert is used to quantify the mechanical strength of the aggregates. Ca. 20% of the aggregates are further agglomerated to granules of ca. 35 µm. At all energy levels above a certain threshold, agglomerates break directly into aggregates.

  10. ELECTROMAGNETIC MICROWAVE PROPERTIES OF Fe82B17Cu1 BALL MILLED ALLOY

    NASA Astrophysics Data System (ADS)

    Tian, N.; Fan, X. D.; Wang, J. W.; You, C. Y.; Lu, Z. X.; Ge, L. L.

    2013-07-01

    High saturation magnetization and magnetic anisotropy are helpful for getting a high frequency electromagnetic microwave absorption performance. The α-Fe possesses a high saturation magnetization. Fe-B phases exhibit a relatively higher magnetic anisotropy and higher resistivity than α-Fe simultaneously. In this work, we made nanocrystalline powders of Fe82B17Cu1, mainly consisting of α-Fe and Fe2B phases, by ball milling and post-annealing. Electromagnetic microwave characterization shows that Fe82B17Cu1 powders possess a relative high permeability and considerable permittivity. Due to a good electromagnetic impedance matching, a good electromagnetic microwave absorption property (RL < -35 dB) has been achieved at 3.6 GHz. The experimental frequency and the matching thickness are coincident with the quarter wavelength matching condition.

  11. Influence of milling time on fineness of Centella Asiatica particle size produced using planetary ball mill

    NASA Astrophysics Data System (ADS)

    Borhan, M. Z.; Ahmad, R.; Rusop, M.; Abdullah, S.

    2012-11-01

    Centella Asiatica (C. Asiatica)contains asiaticoside as bioactive constituent which can be potentially used in skin healing process. Unfortunately, the normal powders are difficult to be absorbed by the body effectively. In order to improve the value of use, nano C. Asiatica powder was prepared. The influence of milling time was carried out at 0.5, 2, 4, 6, 8 hours and 10 hours. The effect of ball milling at different times was characterized using particles size analysis and FTIR Spectroscopy. The fineness of ground product was evaluated by recording the z-Average (nm), undersize distribution and polydispersity index (PdI). The results show that the smallest size particles by mean is 233 nm while FTIR spectra shows that there is no changing in the major component in the C. Asiatica powders with milling time.

  12. Effects of concurrent ball milling and octenyl succinylation on structure and physicochemical properties of starch.

    PubMed

    Li, Nannan; Niu, Meng; Zhang, Binjia; Zhao, Siming; Xiong, Shanbai; Xie, Fengwei

    2017-01-02

    This work concerns the effects of concurrent ball milling (BM) and octenyl succinic anhydride (OSA) modification on the starch microstructure and physicochemical properties (swelling, emulsifying, and rheological). Unlike normal OSA-modified starches, the BM/OSA-modified starch displayed new features such as reduced viscosity and rigidity but increased paste stability during shearing, heating and cooling, regardless of the substitution degree. More interestingly, while the physicochemical properties could be regulated by simply altering the BM treatment time, BM/OSA was more efficient and effective at modulating starch properties during the initial period (approx. 10h), as seen by the rapid evolutions in starch structural disruption and OSA esterification. Thus, the BM/OSA modification can serve as a viable and cost-effective approach for producing octenyl succinate starches where low viscosity (at relatively high concentrations) and high paste stability are desired.

  13. Microwave Absorption Properties of Iron Nanoparticles Prepared by Ball-Milling

    NASA Astrophysics Data System (ADS)

    Chu, Xuan T. A.; Ta, Bach N.; Ngo, Le T. H.; Do, Manh H.; Nguyen, Phuc X.; Nam, Dao N. H.

    2016-05-01

    A nanopowder of iron was prepared using a high-energy ball milling method, which is capable of producing nanoparticles at a reasonably larger scale compared to conventional chemical methods. Analyses using x-ray diffraction and magnetic measurements indicate that the iron nanoparticles are a single phase of a body-centered cubic structure and have quite stable magnetic characteristics in the air. The iron nanoparticles were then mixed with paraffin and pressed into flat square plates for free-space microwave transmission and reflection measurements in the 4-8 GHz range. Without an Al backing plate, the Fe nanoparticles seem to only weakly absorb microwave radiation. The reflected signal S 11 drops to zero and a very large negative value of reflection loss ( RL) are observed for Al-backed samples, suggesting the existence of a phase matching resonance near frequency f ˜ 6 GHz.

  14. Characterisation of an Al-BN nanocomposite prepared by ball milling and hot extrusion

    NASA Astrophysics Data System (ADS)

    Arlic, U.; Drozd, Z.; Trojanová, Z.; Molnárová, O.; Kasakewitsch, A.

    2017-07-01

    Aluminium-matrix-nanocomposites were manufactured by ball milling of microscale aluminium powder with BN nanoparticles in air, followed by subsequent consolidation by hot extrusion. The microstructure of the samples was studied using scanning electron microscopy. Vickers microhardness measurements were used to probe the mechanical properties of the samples. The amplitude dependent damping of the nanocomposites was measured at room temperature after thermal treatment of samples, and the linear thermal expansion was measured over a wide temperature range from room temperature up to 670K in the as-extruded state. The experimental results give a comprehensive picture of the behaviour of this nanocomposite system over the range of thermomechanical treatment conditions examined in this study. Based on these experimental data some possible influences of BN nanoparticles on the anelastic, plastic and thermal properties of microcrystalline aluminium are discussed.

  15. Production of chromium base alloys by ball milling in hydrogen iodide

    NASA Technical Reports Server (NTRS)

    Arias, A.

    1975-01-01

    The effects of processing variables on the tensile properties and ductile-to-brittle transition temperature (DBTT) of Cr + 4 vol% ThO2 alloys and of pure Cr produced by ball milling in hydrogen iodide were investigated. Hot rolled Cr + ThO2 was stronger than either hot pressed Cr + ThO2 or pure Cr at temperatures up to 1540 C. Hot pressed Cr + ThO2 had a DBTT of 500 C as compared with -8 to 24 C for the hot rolled Cr + ThO2 and with 140 C for pure Cr. It is postulated that the dispersoid in the hot rolled alloys lowers the DBTT by inhibiting recovery and recrystallization of the strained structure.

  16. Raman studies of Ball mill synthesized bulk Cu2ZnSnSe4

    NASA Astrophysics Data System (ADS)

    Tiwari, Kunal J.; Prem Kumar D., S.; Mallik, Ramesh Chandra; Malar, P.

    2017-05-01

    Kesterite with chemical formula Cu2ZnSnSe4 (CZTSe) has been synthesized by ball milling followed by annealing and hot pressing. Mechanochemical synthesis was carried out in the presence of process control agent namely toluene under two different milling conditions. Structural and phase evolution during different stages of the synthesis was studied with X-ray diffraction (XRD) and Raman spectroscopy. Near resonant Raman spectrum was obtained by making use of laser wavelength of 488 nm to resolve the presence of secondary ZnSe which otherwise is difficult to conclude with XRD alone. Deconvoluted Raman spectrum confirmed the presence of CZTSe along with secondary phases Cu2SnSe3 (CTSe) and ZnSe. This inference was further confirmed by electron probe micro analysis (EPMA) and wavelength dispersive spectroscopy (WDS) studies.

  17. Hydration of anhydrite of gypsum (CaSO{sub 4}.II) in a ball mill

    SciTech Connect

    Sievert, T.; Wolter, A.; Singh, N.B

    2005-04-01

    The hydration of an anhydrite of gypsum (CaSO{sub 4}.II) in a ball mill was studied as a function of time and temperature. The amount of gypsum formed at different intervals of time was determined by weight loss method and powder X-ray diffraction technique. Specific surface area at different time intervals was determined by LASER granulometric method. The results showed that the maximum rate of formation of gypsum was at a longer time than the time for the development of maximum specific surface area. In the presence of activators, the time for maximum rate of gypsum formation and maximum specific surface area shifted towards lower hydration time. Morphological changes during the course of hydration have been studied by the scanning electron microscopic (SEM) technique. A mechanism of hydration has been proposed.

  18. Cross-Coupling Biarylation of Nitroaryl Chlorides Through High Speed Ball Milling

    PubMed Central

    Lam, Solita; Puplampu-Dove, Yvonne; Morris, Adrienne; Epps, Ayunna; Mandouma, Ghislain

    2016-01-01

    Solvent-free reaction using a high-speed ball milling technique has been applied to the classical Ullmann coupling reaction. Cross-coupling biarylation of several nitroaryl chlorides was achieved in good yields when performed in custom-made copper vials through continuous shaking without additional copper or solvent. Cross-coupling products were obtained almost pure and NMR-ready. These reactions were cleaner than solution phase coupling which require longer reaction time in high boiling solvents, and added catalysts as well as lengthy extraction and purification steps. Gram quantities of cross biaryl compounds have been synthesized with larger copper vials, a proof that this method can be used to reduce industrial waste and for sustainability. PMID:27294205

  19. Hydrogen storage materials discovery via high throughput ball milling and gas sorption.

    PubMed

    Li, Bin; Kaye, Steven S; Riley, Conor; Greenberg, Doron; Galang, Daniel; Bailey, Mark S

    2012-06-11

    The lack of a high capacity hydrogen storage material is a major barrier to the implementation of the hydrogen economy. To accelerate discovery of such materials, we have developed a high-throughput workflow for screening of hydrogen storage materials in which candidate materials are synthesized and characterized via highly parallel ball mills and volumetric gas sorption instruments, respectively. The workflow was used to identify mixed imides with significantly enhanced absorption rates relative to Li2Mg(NH)2. The most promising material, 2LiNH2:MgH2 + 5 atom % LiBH4 + 0.5 atom % La, exhibits the best balance of absorption rate, capacity, and cycle-life, absorbing >4 wt % H2 in 1 h at 120 °C after 11 absorption-desorption cycles.

  20. Solid acid-catalyzed depolymerization of barley straw driven by ball milling.

    PubMed

    Schneider, Laura; Haverinen, Jasmiina; Jaakkola, Mari; Lassi, Ulla

    2016-04-01

    This study describes a time and energy saving, solvent-free procedure for the conversion of lignocellulosic barley straw into reducing sugars by mechanocatalytical pretreatment. The catalytic conversion efficiency of several solid acids was tested which revealed oxalic acid dihydrate as a potential catalyst with high conversion rate. Samples were mechanically treated by ball milling and subsequently hydrolyzed at different temperatures. The parameters of the mechanical treatment were optimized in order to obtain sufficient amount of total reducing sugar (TRS) which was determined following the DNS assay. Additionally, capillary electrophoresis (CE) and Fourier transform infrared spectrometry (FT-IR) were carried out. Under optimal conditions TRS 42% was released using oxalic acid dihydrate as a catalyst. This study revealed that the acid strength plays an important role in the depolymerization of barley straw and in addition, showed, that the oxalic acid-catalyzed reaction generates low level of the degradation product 5-hydroxymethylfurfural (HMF).

  1. Production of chromium base alloys by ball milling in hydrogen iodide

    NASA Technical Reports Server (NTRS)

    Arias, A.

    1975-01-01

    The effects of processing variables on the tensile properties and ductile-to-brittle transition temperature (DBTT) of Cr + 4 vol% ThO2 alloys and of pure Cr produced by ball milling in hydrogen iodide were investigated. Hot rolled Cr + ThO2 was stronger than either hot pressed Cr + ThO2 or pure Cr at temperatures up to 1540 C. Hot pressed Cr + ThO2 had a DBTT of 500 C as compared with -8 to 24 C for the hot rolled Cr + ThO2 and with 140 C for pure Cr. It is postulated that the dispersoid in the hot rolled alloys lowers the DBTT by inhibiting recovery and recrystallization of the strained structure.

  2. Enhancing the enzymatic hydrolysis of cellulosic materials using simultaneous ball milling.

    PubMed

    Mais, Ursula; Esteghlalian, Ali R; Saddler, John N; Mansfield, Shawn D

    2002-01-01

    One of the limiting factors restricting the effective and efficient bioconversion of softwood-derived lignocellulosic residues is the recalcitrance of the substrate following pretreatment. Consequently, the ensuing enzymatic process requires relatively high enzyme loadings to produce monomeric carbohydrates that are readily fermentable by ethanologenic microorganisms. In an attempt to circumvent the need for larger enzyme loadings, a simultaneous physical and enzymatic hydrolysis treatment was evaluated. A ball-mill reactor was used as the digestion vessel, and the extent and rate of hydrolysis were monitored. Concurrently, enzyme adsorption profiles and the rate of conversion during the course of hydrolysis were monitored. alpha-Cellulose, employed as a model substrate, and SO2-impregnated steam-exploded Douglas-fir wood chips were assessed as the cellulosic substrates. The softwood-derived substrate was further posttreated with water and hot alkaline hydrogen peroxide to remove >90% of the original lignin. Experiments at different reaction conditions were evaluated, including substrate concentration, enzyme loading, reaction volumes, and number of ball beads employed during mechanical milling. It was apparent that the best conditions for the enzymatic hydrolysis of alpha-cellulose were attained using a higher number of beads, while the presence of air-liquid interface did not seem to affect the rate of saccharification. Similarly, when employing the lignocellulosic substrate, up to 100% hydrolysis could be achieved with a minimum enzyme loading (10 filter paper units/g of cellulose), at lower substrate concentrations and with a greater number of reaction beads during milling. It was apparent that the combined strategy of simultaneous ball milling and enzymatic hydrolysis could improve the rate of saccharification and/or reduce the enzyme loading required to attain total hydrolysis of the carbohydrate moieties.

  3. Preparation, characterization and optoelectronic properties of nanodiamonds doped zinc oxide nanomaterials by a ball milling technique

    NASA Astrophysics Data System (ADS)

    Ullah, Hameed; Sohail, Muhammad; Malik, Uzma; Ali, Naveed; Bangash, Masroor Ahmad; Nawaz, Mohsan

    2016-07-01

    Zinc oxide (ZnO) is one of the very important metal oxides (MOs) for applications in optoelectronic devices which work in the blue and UV regions. However, to meet the challenges of obtaining ZnO nanomaterials suitable for practical applications, various modifications in physico-chemical properties are highly desirable. One of the ways adopted for altering the properties is to synthesize composite(s) of ZnO with various reinforcements. Here we report on the tuning of optoelectronic properties of ZnO upon doping by nanodiamonds (NDs) using the ball milling technique. A varying weight percent (wt.%) of NDs were ball milled for 2 h with ZnO nanoparticles prepared by a simple precipitation method. The effects of different parameters, the calcination temperature of ZnO, wt.% of NDs and mechanical milling upon the optoelectronic properties of the resulting ZnO-NDs nanocomposites have been investigated. The ZnO-NDs nanocomposites were characterized by IR spectroscopy, powder x-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDX). The UV-vis spectroscopy revealed the alteration in the bandgap energy (Eg ) of ZnO as a function of the calcination temperature of ZnO, changing the concentration of NDs, and mechanical milling of the resulting nanocomposites. The photoluminescence (PL) spectroscopy showed a decrease in the deep level emission (DLE) peaks and an increase in near-band-edge transition peaks as a result of the increasing concentration of NDs. The decrease in DLE and increase in band to band transition peaks were due to the strong interaction between the NDs and the Zn+; consequently, the Zn+ concentration decreased on the interstitial sites.

  4. Seebeck and thermal conductivity analysis in amorphous/crystalline {beta}-K{<_2}Bi{<_8}Se{<_13} nanocomposite materials.

    SciTech Connect

    Kyratsi, Th.; Hatzikraniotis, E.; Ioannou, M.; Chung, D. Y.; Tsiaoussis, I.

    2011-01-01

    In this work, ball milling is applied on {beta}-K{sub 2}Bi{sub 8}Se{sub 13} compounds in order to explore the potential of the process for the fabrication of nano-based material. Polycrystalline {beta}-K{sub 2}Bi{sub 8}Se{sub 13}, synthesized from melt, was ball milled under inert atmosphere. Powder x-ray diffraction showed a significantly increased disorder with ball milling time. TEM studies confirmed the presence of nanocrystalline material in an amorphous matrix, suggesting the development of crystalline/amorphous {beta}-K{sub 2}Bi{sub 8}Se{sub 13} nanocomposite material via ball milling process. Seebeck coefficient and thermal conductivity were analyzed based on the effective medium theory and show a significant contribution of a nanocrystalline phase.

  5. Effects of ball milling and sintering on alumina and alumina-boron compounds

    NASA Astrophysics Data System (ADS)

    Cross, Thomas

    Alumina has a wide variety of applications, but the processing of alumina based materials can be costly. Mechanically milling alumina has been shown to enhance the sintering properties while decreasing the sintering temperature. Additions of boron have also proven to increase sintering properties of alumina. These two processes, mechanical milling and boron additions, will be combined to test the sintering properties and determine if they are improved upon even further compared to the individual processes. Multiple samples of pure alumina, 0.2 weight percent boron, and 1.0 weight percent boron are batched and processed in a ball mill for different time intervals. These samples are then characterized to observe the structure and properties of the samples after milling but before sintering. Pellets are dry pressed from the milled powders, sintered at 1200°C for one to 10 hours, and characterized to determine the impact of processing. X-ray diffractometry (XRD) was used on each sample to determine crystallite size and lattice parameters at different stages throughout the experiment. XRD was also used to identify any samples with an aluminum borate phase. Scanning electron microscopy (SEM) was used to observe the powder and pellet morphology and to measure bulk chemical composition. Samples were sputter coated with an Au-Pd coating observed in the SEM to characterize the topography as a function of variables such as milling time, boron composition, and sintering time. Additionally, porosity and change in diameter were measured to track the sintering process. Milling sample for longer periods of time would be unnecessary due to the crystallite size leveling off between 10 and 12 hours of milling time. Samples of alumina with 0.2 weight percent boron prove to have very little effect on the sintering properties. At 1.0 weight percent boron, there are changes in diffraction patterns and topography after being sintered for one hour. The porosities of all of the sintered

  6. Production of pyrite nanoparticles using high energy planetary ball milling for sonocatalytic degradation of sulfasalazine.

    PubMed

    Khataee, Alireza; Fathinia, Siavash; Fathinia, Mehrangiz

    2017-01-01

    Sonocatalytic performance of pyrite nanoparticles was evaluated by the degradation of sulfasalazine (SSZ). Pyrite nanoparticles were produced via a high energy mechanical ball milling (MBM) in different processing time from 2h to 6h, in the constant milling speed of 320rpm. X-ray diffraction (XRD), scanning electron microscopy (SEM) coupled with energy dispersive X-ray (EDX), Fourier transform infrared spectroscopy (FT-IR) analysis and Brunauer-Emmett-Teller (BET) confirmed the production of pyrite nanoparticles during 6h of ball milling with the average size distribution of 20-80nm. The effects of various operational parameters including pH value, catalyst amount (mg/L), SSZ concentration (mg/L), ultrasonic frequency (kHz) and reaction time on the SSZ removal efficiency were examined. The obtained results showed that the maximum removal efficiency of 97.00% was obtained at pH value of 4, catalyst dosage of 0.5g/L, SSZ concentration of 10mg/L and reaction time of 30min. Experimental results demonstrated that the kinetic of the degradation process can be demonstrated using Langmuir-Hinshelwood (L-H) kinetic model. The effect of different inorganic ions such as Cl(-), CO3(2-) and SO4(2-) was investigated on the L-H reaction rate (kr) and adsorption (Ks) constants. Results showed that the presence of the mentioned ions significantly influenced the L-H constants. The impact of ethanol as a OH radical scavenger and some enhancers including H2O2 and K2S2O8 was investigated on the SSZ removal efficiency. Accordingly, the presence of ethanol suppressed SSZ degradation due to the quenching of OH radicals and the addition of K2S2O8 and H2O2 increased the SSZ removal efficiency, due to the formation of SO4(-) and additional OH radicals, respectively. Under the identical conditions of operating parameters, pyrite nanoparticles maintained their catalytic activity during four consecutive runs. Copyright © 2016 Elsevier B.V. All rights reserved.

  7. Solid State Reaction Mechanism and Microstructure Evolution of Ni-Al Powders during High Energy Ball Milling Revisited by TEM.

    PubMed

    Fan, Guohua; Geng, Lin; Feng, Yicheng; Cui, Xiping; Yan, Xudong

    2015-08-01

    Microstructure evolution during the formation of B2-NiAl by high energy ball milling of equiatomic elemental mixtures was studied by X-ray diffractometer, scanning electron microscopy, and transmission electron microscopy (TEM). The crystallite size, lattice defects and ordering of the B2-NiAl were monitored via TEM as function of milling time. The diffusion reaction, Ni+Al→NiAl3 or/and Ni2Al3, occurred during high energy ball milling, and to a certain extent offered the stored energy for the explosive exothermic reaction, Ni+Al→B2-NiAl. The fine microstructure of newly formed B2-NiAl after 5 h milling involved high density defects, e.g. antiphase boundary, long range ordering domains, vacancies, and dislocations.

  8. Significant disorder-induced enhancement of the magnetization of Fe2CrGa by ball milling

    NASA Astrophysics Data System (ADS)

    Zhang, H. G.; Zhang, C. Z.; Zhu, W.; Liu, E. K.; Wang, W. H.; Zhang, H. W.; Cheng, J. L.; Luo, H. Z.; Wu, G. H.

    2013-07-01

    It is reported that ball milling gives rise to a different atomic configuration in Fe2CrGa than the order obtained upon preparation by arc melting. After ball milling, the magnetic moment has values of 3.2 to 3.9 μB/f.u., which is significantly higher than in arc-melted samples, and the Curie temperature increases by about 200 K. Combination of first-principles calculations and experimental results indicates that Fe2CrGa crystallizes in the Hg2CuTi-based structures with either Fe-Ga or Cr-Ga disorder, depending on the preparation method. It is shown that magnetic interactions play a crucial role in adopting atomic configurations which disobey the empirical rule.

  9. Synthesis of stoichiometric Ca2Fe2O5 nanoparticles by high-energy ball milling and thermal annealing

    NASA Astrophysics Data System (ADS)

    Amorim, B. F.; Morales, M. A.; Bohn, F.; Carriço, A. S.; de Medeiros, S. N.; Dantas, A. L.

    2016-05-01

    We report the synthesis of Ca2Fe2O5 nanoparticles by high-energy ball milling and thermal annealing from α-Fe2O3 and CaCO3. Magnetization measurements, Mössbauer and X-ray spectra reveal that annealing at high temperatures leads to better quality samples. Our results indicate nanoparticles produced by 10 h high-energy ball milling and thermal annealing for 2 h at 1100 °C achieve improved stoichiometry and the full weak ferromagnetic signal of Ca2Fe2O5. Samples annealed at lower temperatures show departure from stoichiometry, with a higher occupancy of Fe3+ in octahedral sites, and a reduced magnetization. Thermal relaxation for temperatures in the 700-1100 °C range is well represented by a Néel model, assuming a random orientation of the weak ferromagnetic moment of the Ca2Fe2O5 nanoparticles.

  10. Acid-Assisted Ball Milling of Cellulose as an Efficient Pretreatment Process for the Production of Butyl Glycosides.

    PubMed

    Boissou, Florent; Sayoud, Nassim; De Oliveira Vigier, Karine; Barakat, Abdellatif; Marinkovic, Sinisa; Estrine, Boris; Jérôme, François

    2015-10-12

    Ball milling of cellulose in the presence of a catalytic amount of H2SO4 was found to be a promising pre-treatment process to produce butyl glycosides in high yields. Conversely to the case of water, n-butanol has only a slight effect on the recrystallization of ball-milled cellulose. As a result, thorough depolymerization of cellulose prior the glycosylation step is no longer required, which is a pivotal aspect with respect to energy consumption. This process was successfully transposed to wheat straw from which butyl glycosides and xylosides were produced in good yields. Butyl glycosides and xylosides are important chemicals as they can be used as hydrotropes but also as intermediates in the production of valuable amphiphilic alkyl glycosides.

  11. Combined pretreatment using alkaline hydrothermal and ball milling to enhance enzymatic hydrolysis of oil palm mesocarp fiber.

    PubMed

    Zakaria, Mohd Rafein; Hirata, Satoshi; Hassan, Mohd Ali

    2014-10-01

    Hydrothermal pretreatment of oil palm mesocarp fiber was conducted in tube reactor at treatment severity ranges of log Ro = 3.66-4.83 and partial removal of hemicellulose with migration of lignin was obtained. Concerning maximal recovery of glucose and xylose, 1.5% NaOH was impregnated in the system and subsequent ball milling treatment was employed to improve the conversion yield. The effects of combined hydrothermal and ball milling pretreatments were evaluated by chemical composition changes by using FT-IR, WAXD and morphological alterations by SEM. The successful of pretreatments were assessed by the degree of enzymatic digestibility of treated samples. The highest xylose and glucose yields obtained were 63.2% and 97.3% respectively at cellulase loadings of 10 FPU/g-substrate which is the highest conversion from OPMF ever reported.

  12. ZnO nanoparticles obtained by ball milling technique: Structural, micro-structure, optical and photo-catalytic properties

    SciTech Connect

    Balamurugan, S. Joy, Josny; Godwin, M. Anto; Selvamani, S.; Raja, T. S. Gokul

    2016-05-23

    The ZnO nanoparticles were obtained by ball milling of commercial grade ZnO powder at 250 rpm for 20 h and studied their structural, micro-structure, optical and photo-catalytic properties. Due to ball milling significant decrease in lattice parameters and average crystalline size is noticed for the as-milled ZnO nano powder. The HRSEM images of the as-milled powder consist of agglomerated fine spherical nanoparticles in the range of ~10-20 nm. The room temperature PL spectrum of as-milled ZnO nano powder excited under 320 nm reveals two emission bands at ~406 nm (violet emission) and ~639 nm (green emission). Interestingly about 98 % of photo degradation of methylene (MB) by the ZnO catalyst is achieved at 100 minutes of solar light irradiation.

  13. Noble-Metal-Free Photocatalytic Hydrogen Evolution Activity: The Impact of Ball Milling Anatase Nanopowders with TiH2.

    PubMed

    Zhou, Xuemei; Liu, Ning; Schmidt, Jochen; Kahnt, Axel; Osvet, Andres; Romeis, Stefan; Zolnhofer, Eva M; Marthala, Venkata Ramana Reddy; Guldi, Dirk M; Peukert, Wolfgang; Hartmann, Martin; Meyer, Karsten; Schmuki, Patrik

    2017-02-01

    Ball milling TiO2 anatase together with TiH2 can create an effective photocatalyst. The process changes the lattice and electronic structure of anatase. Lattice deformation created by mechanical impact combined with hydride incorporation yield electronic gap-states close to the conduction band of anatase. These provide longer lifetimes of photogenerated charge carriers and lead to an intrinsic cocatalytic activation of anatase for H2 evolution.

  14. Enhancement of thermoelectric performance of ball-milled bismuth due to spark-plasma-sintering-induced interface modifications.

    PubMed

    Puneet, Pooja; Podila, Ramakrishna; Zhu, Song; Skove, Malcolm J; Tritt, Terry M; He, Jian; Rao, Apparao M

    2013-02-20

    Interface modification in transport properties of single elemental polycrystalline Bi via spark plasma sintering results in 'double-decoupling' (simultaneous decoupling of thermopower, electrical, and thermal conductivity) of otherwise coupled entities. In spark plasma sintering, the DC pulse current helps in controlling the nature and extent of surfaces of ball-milled Bi and hence results in six-fold improvement in the dimensionless figure of merit (ZT) relative to as-purchased samples.

  15. Structural, optical, morphological and thermal properties of TiO2-Al and TiO2-Al2O3 composite powders by ball milling

    NASA Astrophysics Data System (ADS)

    Mahalingam, T.; Selvakumar, C.; Ranjith Kumar, E.; Venkatachalam, T.

    2017-06-01

    The microstructure and morphology of 70% TiO2-30% Al, 70% TiO2-30% Al2O3, 55% TiO2-045% Al and 55% TiO2-45% Al2O3 composite powders were prepared by Smart Mini Ball Miller. They are characterized by XRD, SEM, EDAX, FTIR and TG/DSC. The XRD results showed that composite powders were mainly in the amorphous anatase phase with high crystallinity. The SEM study of composite powders reveals the average particle size is 100 ± 20 nm. In FTIR, peaks observed at around 460 cm-1-560 cm-1 represent bending vibrations of Ti-O-Ti groups in the composite powders. In TG/DSC analysis, there is weight gain in TiO2-Al composite powders where as weight loss in TiO2-Al2O3 composite powders. Finally, microstructure and characterizations of the composite powders during ball milling were investigated to propose an optimal route for obtaining composite powders suitable for thermal spray process.

  16. High energy ball-milled Ti{sub 2}RuFe electrocatalyst for hydrogen evolution in the chlorate industry

    SciTech Connect

    Blouin, M.; Guay, D.; Huot, J.; Schulz, R.

    1997-06-01

    The high energy mechanical alloying of a Ti{endash}Ru{endash}Fe powder mixture (atomic ratio 2:1:1) has been performed by extensive ball-milling in a steel crucible. The structural evolution of the resulting materials has been studied by x-ray powder diffraction analysis. The identification of the various phases present in the materials, as well as the crystallite size and strain, has been performed by Rietveld refinement analysis. In the first stage of the material transformation, Ru or Fe atoms dissolved into Ti to yield to the formation of {beta}{minus}Ti. Upon further ball-milling, almost all the original constituents of the powder mixture have disappeared and a new simple cubic Ti{sub 2}RuFe phase is formed, with a crystallite size as small as 8 nm. The electrochemical properties of these materials have been tested in a typical chlorate electrolyte by cold-pressing the powders into disk electrodes. At 20 h of ball-milling, where the phase concentration of Ti{sub 2}RuFe reaches 96{percent}, a reduction of the activation overpotential at 250 mA cm{sup {minus}2} of nearly 250 mV is observed when compared to that of a pure iron electrode. {copyright} {ital 1997 Materials Research Society.}

  17. Study on preparation of the core-nanoshell composite absorbers by high-energy ball milling at room temperature.

    PubMed

    Che, Ruxin; Gao, Hong; Yu, Bing; Wang, Shuo; Wang, Chunxia

    2012-02-01

    Electromagnetic (EM) wave pollution has become the chief physical pollution for environment. In recent years, some researches have been focused on the preparation of nano-composite absorbers at low temperatures or even at room temperature. In this letter, preparation of nanocomposite by using high-energy ball milling at room temperature is reported. The core-nanoshell composite absorbers with magnetic fly-ash hollow cenosphere (MFHC) as nuclear and nanocrystalline magnetic material as shell were prepared by high-energy ball milling and vacuum-sintering in this paper. The pre-treatment of MFHC, the sintering process and the mol ratio of starting chemicals had a significant impact for property of composite absorbers. The results of X-ray diffraction analysis (XRD), transmission electron microscope (TEM), vibrating sample magnetometer (VSM) and vector network analyzer (VNA) analysis indicated that perfect-crystalline nanomagnetic material coating was gotten with a particle size of 12 nm after ball milling. The results show the MFHC is dielectric loss and magnetic loss too; the exchange-coupling interaction happened between ferrite of the MFHC and nanocrystalline magnetic material coating. The exchange-coupling interaction enhances magnetic loss of composite absorbers. They have a perfect EM parameters at low microwave frequency. The core-nanoshell composite absorbers have a higher magnetic loss at low frequencies, and it is consistent with requirements of the microwave absorbing material at the low-frequency absorption. The microwave absorptivity of the core-nanoshell composite absorbers is better than single material.

  18. Highly anisotropic SmCo5 nanoflakes by surfactant-assisted ball milling at low temperature

    NASA Astrophysics Data System (ADS)

    Liu, Lidong; Zhang, Songlin; Zhang, Jian; Ping Liu, J.; Xia, Weixing; Du, Juan; Yan, Aru; Yi, Jianhong; Li, Wei; Guo, Zhaohui

    2015-01-01

    Surfactant-assisted ball milling (SABM) has been shown to be a promising method for preparing rare earth-transition metal (RE-TM) nanoflakes and nanoparticles. In this work, we prepared SmCo5 nanoflakes by SABM at low temperature, and 2-methyl pentane and trioctylamine were specially selected as solvent and surfactant, respectively, due to their low melting points. The effects of milling temperature on the morphology, microstructure and magnetic performance of SmCo5 nanoflakes were investigated systematically. Comparing with the samples milled at room temperature, the SmCo5 nanoflakes prepared at low temperature displayed more homogeneous morphology and lower oxygen content. Remarkably, better crystallinity, better grain alignment and larger remanence ratio were shown in the samples milled at low temperature, which resulted from the distinct microstructure caused by low milling temperature. The differences in structural evolution between the SmCo5 nanoflakes milled at room temperature and low temperature, including the formation of nanocrystalline, grain boundary sliding, grain rotation, et al., were discussed. It was found that lowering the temperature of SABM was a powerful method for the fabrication of RE-TM nanoflakes, which showed better hard magnetic properties and lower oxygen content. This was important for the preparation of high-performance sintered magnets, bonded magnets and nanocomposite magnets.

  19. Insertion compounds and composites made by ball milling for advanced sodium-ion batteries

    PubMed Central

    Zhang, Biao; Dugas, Romain; Rousse, Gwenaelle; Rozier, Patrick; Abakumov, Artem M.; Tarascon, Jean-Marie

    2016-01-01

    Sodium-ion batteries have been considered as potential candidates for stationary energy storage because of the low cost and wide availability of Na sources. However, their future commercialization depends critically on control over the solid electrolyte interface formation, as well as the degree of sodiation at the positive electrode. Here we report an easily scalable ball milling approach, which relies on the use of metallic sodium, to prepare a variety of sodium-based alloys, insertion layered oxides and polyanionic compounds having sodium in excess such as the Na4V2(PO4)2F3 phase. The practical benefits of preparing sodium-enriched positive electrodes as reservoirs to compensate for sodium loss during solid electrolyte interphase formation are demonstrated by assembling full C/P′2-Na1[Fe0.5Mn0.5]O2 and C/‘Na3+xV2(PO4)2F3' sodium-ion cells that show substantial increases (>10%) in energy storage density. Our findings may offer electrode design principles for accelerating the development of the sodium-ion technology. PMID:26777573

  20. Surface hardening of Al alloys through controlled ball-milling and sintering.

    PubMed

    Kim, Seek Hyeoun; Kim, Yong Jin; Ahn, Jung-Ho

    2012-07-01

    One of the drawbacks of aluminum and its alloys is the lack of proper heat-treatment for surface-hardening. In the present work, a new and simple method of hardening the surface of aluminum and its alloys was developed. Low-energy ball-milling using specific process control agents (PCAs) was employed, using subsequent sintering in a controlled atmosphere. The PCAs in the present work were very effective both for milling and the formation of hard nanocrystalline dispersoids during sintering. The residual oxygen in a sintering atmosphere also played an important role in the formation of AIN or Al-O-N dispersoids. Through the proper control of the processing atmosphere and PCAs, the hardness and thickness of the hardened layers could be adjusted. The results of the wear test showed that the present aluminum alloys can be effectively utilized as light-weight components with a good wear resistance. Furthermore, the present method involves a simple forming process of die-compaction and sintering.

  1. Characterization of cationic starch flocculants synthesized by dry process with ball milling activating method.

    PubMed

    Su, Yuting; Du, Hongying; Huo, Yinqiang; Xu, Yongliang; Wang, Jie; Wang, Liying; Zhao, Siming; Xiong, Shanbai

    2016-06-01

    The cationic starch flocculants were synthesized by the reaction of maize starch which was activated by a ball-milling treatment with 2,3-epoxypropyl trimethyl ammonium chlorides (ETMAC) using the dry method. The cationic starches were characterized by several approaches including scanning electron microscope (SEM), degree of substitution (DS), infrared spectrum (IR), X-ray diffraction (XRD), flocculating activity, electron spin resonance (ESR), and solid-state nuclear magnetic resonance (NMR). The effect of mechanical activation on starch etherifying modification was investigated. The mechanical activation cracked starch granules and destructed their crystal structures. This resulted in enhancements to the reaction activity and reaction efficiency, which was approved by ESR and solid state NMR. The starch flocculants, synthesized by the reaction of mechanically activated starches at 90°C for 2.5h with ETMAC at molar ratio of 0.40:1.00, showed good flocculation activity. The substitution degree (0.300) and reaction efficiency (75.06%) of starch flocculants synthesized with mechanically activated starches were significantly greater than those of starch flocculants with native starches (P<0.05).

  2. TEM and HRTEM studies of ball milled 6061 aluminium alloy powder with Zr addition.

    PubMed

    Lityńska-Dobrzyńska, L; Dutkiewicz, J; Maziarz, W; Rogal, Ł

    2010-03-01

    The effect of mechanical alloying on the microstructure of atomized 6061 aluminium alloy powder and 6061 powder with a zirconium addition was studied in the work. The atomized 6061 aluminium alloy powder and 6061 powder with addition of 2 wt.% Zr were milled in a planetary ball mill and investigated using X-ray diffraction measurements, conventional and high-resolution electron microscopy (TEM/HRTEM) and high-angle annular dark field scanning transmission electron microscopy combined with energy dispersive X-ray microanalysis. An increase of stresses was observed in milled powders after the refinement of crystallites beyond 100 nm. In the powder with zirconium addition, some part of the Zr atoms diffused in aluminium forming a solid solution containing up to 0.5 wt.% Zr. The remaining was found to form Zr-rich particles containing up to 88 wt.% Zr and were identified as face centred cubic (fcc) phase with lattice constant a= 0.48 nm. That fcc phase partially transformed into the L1(2) ordered phase. Eighty-hour milling brought an increase of microhardness (measured with Vickers method) from about 50 HV (168 MPa) for the initial 6061 powder to about 170 HV (552 MPa). The addition of zirconium had no influence on the microhardness.

  3. The effects of attrition and ball milling on the properties of magnesium diboride

    NASA Astrophysics Data System (ADS)

    Dancer, C. E. J.; Prabhakaran, D.; Crossley, A.; Todd, R. I.; Grovenor, C. R. M.

    2010-06-01

    Commercially produced magnesium diboride powder was modified by attrition milling and ball milling in propan-2-ol for various durations. These powders were characterized by means of particle size distribution measurements using laser diffraction, impurity analysis using x-ray diffraction, energy dispersive spectroscopy and x-ray photoelectron spectroscopy, and scanning electron microscopy, and were then used to produce magnesium diboride samples through pressureless heat treatment at peak temperatures up to 1100 °C. X-ray diffraction, scanning electron microscopy, Vickers hardness measurements, and density measurements using the Archimedes method were used to characterize the properties of the samples, and a determination of their superconducting properties using the magnetization method was carried out. Magnesium diboride produced from powder milled under certain conditions had a higher Jc, mag than samples produced from as-purchased powder, but the relationship between the milling duration or energy and the superconducting performance is a complex one, affected by both the particle size and the impurity content of the starting powder.

  4. The coercivity mechanism of Pr-Fe-B nanoflakes prepared by surfactant-assisted ball milling

    NASA Astrophysics Data System (ADS)

    Zuo, Wen-Liang; Zhang, Ming; Niu, E.; Shao, Xiao-Ping; Hu, Feng-Xia; Sun, Ji-Rong; Shen, Bao-Gen

    2015-09-01

    The strong (00l) textured Pr12+xFe82-xB6 (x=0, 1, 2, 3, 4) nanoflakes with high coercivity were prepared by surfactant-assisted ball milling (SABM). The thickness and length of the flakes are mainly in the range of 50-200 nm and 0.5-2 μm, respectively. A coercivity of 4.16 kOe for Pr15Fe79B6 nanoflakes was obtained, which is the maximum coercivity of R2Fe14B (R=Pr, Nd) nanoflakes or nanoparticles reported up to now. The results of XRD and SEM for the aligned Pr15Fe79B6 nanoflakes indicate that a strong (00l) texture is obtained and the easy magnetization direction is parallel to the surface of the flakes. The angular dependence of coercivity for aligned sample indicates that the coercivity mechanism of the as-milled nanoflakes is mainly dominated by domain wall pinning. Meanwhile, the field dependence of coercivity, isothermal (IRM) and dc demagnetizing (DCD) remanence curves also indicate that the coercivity is mainly determined by domain wall pinning, and nucleation also has an important effect. In addition, the mainly interaction of flakes is dipolar coupling. The research of coercivity mechanism for Pr15Fe79B6 nanoflakes is important for guidance the further increase its value, and is useful for the future development of the high performance nanocomposite magnets and soft/hard exchange spring magnets.

  5. Easily recycled Bi2O3 photocatalyst coatings prepared via ball milling followed by calcination

    NASA Astrophysics Data System (ADS)

    Cheng, Lijun; Hu, Xumin; Hao, Liang

    2017-06-01

    Bi2O3 photocatalyst coatings derived from Bi coatings were first prepared by a two-step method, namely ball milling followed by the calcination process. The as-prepared samples were characterized by XRD, SEM, XPS and UV-Vis spectra, respectively. The results showed that monoclinic Bi2O3 coatings were obtained after sintering Bi coatings at 673 or 773 K, while monoclinic and triclinic mixed phase Bi2O3 coatings were obtained at 873 or 973 K. The topographies of the samples were observably different, which varied from flower-like, irregular, polygonal to nanosized particles with the increase in calcination temperature. Photodegradation of malachite green under simulated solar irradiation for 180 min showed that the largest degradation efficiency of 86.2% was achieved over Bi2O3 photocatalyst coatings sintered at 873 K. The Bi2O3 photocatalyst coatings, encapsulated with Al2O3 ball with an average diameter around 1 mm, are quite easily recycled, which provides an alternative visible light-driven photocatalyst suitable for practical water treatment application.

  6. Room temperature dual ferroic behaviour of ball mill synthesized NdFeO{sub 3} orthoferrite

    SciTech Connect

    Aparnadevi, N.; Saravana Kumar, K.; Manikandan, M.; Venkateswaran, C.; Paul Joseph, D.

    2016-07-21

    Phase pure NdFeO{sub 3} has been achieved using high energy ball milling of oxide precursors with subsequent sintering. It is established that structural arrangement of NdFeO{sub 3} regulates the multifunctional feature of the material. Rietveld refinement of the room temperature X-ray diffraction pattern shows that the Fe-O-Fe bond angle significantly favors the super exchange interaction, which is predominantly antiferromagnetic in nature. Magnetization measurement illustrates antiferromagnetic behaviour with a weak ferromagnetic component caused by the canted nature of the Fe{sup 3+} spins at room temperature. Absorption bands in the visible ambit, apparent from the UV-Vis diffuse reflectance studies, is found due to the crystal ligand field of octahedral oxygen environment of Fe{sup 3+} ions. The direct band gap is estimated to be 2.39 eV from the diffuse reflectance spectrum. The lossy natured ferroelectric loop having a maximum polarization of 0.23 μC/cm{sup 2} at room temperature is found to be driven by the non-collinear magnetic structure with reverse Dzyaloshinskii–Moriya effect. Magnetic field has influence on the dielectric constant as evident from the impedance spectroscopy, indicating the strong coupling between ferroelectric and the magnetic structure of NdFeO{sub 3}.

  7. Electromagnetic properties of flake-shaped Fe-Si alloy particles prepared by ball milling

    NASA Astrophysics Data System (ADS)

    Cao, Lei; Jiang, Jian-Tang; Wang, Zeng-Quan; Gong, Yuan-Xun; Liu, Chao; Zhen, Liang

    2014-11-01

    Flake-shaped Fe-Si alloy particles with high aspect ratios were fabricated by ball milling commercially available Fe-Si powder, aiming to fabricate high-performance microwave absorbing fillers for coatings applied in 1-4 GHz range. To compare with spherical particles, higher permittivity and permeability was observed by using flaky particles as fillers. High aspect ratios contributed to an enhanced dielectric relaxation in the 1-4 GHz band, resulting in an increased permittivity. The thin thickness together with the high resistivity of Fe-Si flakes was believed to be helpful for suppressing the effect of eddy current and thus lead to an increase in the permeability. The electromagnetic wave absorbing (EMA) performances were observed to be enhanced. With a thin thickness of 2 mm, a wide absorption band with a minimum reflection loss of -12 dB was achieved in 1-4 GHz range, when using 75 wt% of flaky Fe-Si particles as fillers. The study indicated that flake-shaped Fe-Si particles were a promising candidate for EMA materials in L and S bands.

  8. Niobium Carbide-Reinforced Al Matrix Composites Produced by High-Energy Ball Milling

    NASA Astrophysics Data System (ADS)

    Travessa, Dilermando Nagle; Silva, Marina Judice; Cardoso, Kátia Regina

    2017-06-01

    Aluminum and its alloys are key materials for the transportation industry as they contribute to the development of lightweight structures. The dispersion of hard ceramic particles in the Al soft matrix can lead to a substantial strengthening effect, resulting in composite materials exhibiting interesting mechanical properties and inspiring their technological use in sectors like the automotive and aerospace industries. Powder metallurgy techniques are attractive to design metal matrix composites, achieving a homogeneous distribution of the reinforcement into the metal matrix. In this work, pure aluminum has been reinforced with particles of niobium carbide (NbC), an extremely hard and stable refractory ceramic. Its use as a reinforcing phase in metal matrix composites has not been deeply explored. Composite powders produced after different milling times, with 10 and 20 vol pct of NbC were produced by high-energy ball milling and characterized by scanning electron microscopy and by X-ray diffraction to establish a relationship between the milling time and size, morphology, and distribution of the particles in the composite powder. Subsequently, an Al/10 pct NbC composite powder was hot extruded into cylindrical bars. The strength of the obtained composite bars is comparable to the commercial high-strength, aeronautical-grade aluminum alloys.

  9. Characterization of prealloyed copper powders treated in high energy ball mill

    SciTech Connect

    Rajkovic, Viseslava . E-mail: visnja@vin.bg.ac.yu; Bozic, Dusan; Jovanovic, Milan T.

    2006-08-15

    The inert gas atomised prealloyed copper powders containing 3.5 wt.% Al were milled up to 20 h in the planetary ball mill in order to oxidize aluminium in situ with oxygen from the air. In the next procedure compacts from milled powder were synthesized by hot-pressing in argon atmosphere. Compacts from as-received Cu-3.5 wt.% Al powder and electrolytic copper powder were also prepared under the same conditions. Microstructural and morphological changes of high energy milled powder as well as changes of thermal stability and electrical conductivity of compacts were studied as a function of milling time and high temperature exposure at 800 deg. C. Optical, scanning electron microscopy (SEM) and X-ray diffraction analysis were performed for microstructural characterization, whereas thermal stability and electrical conductivity were evaluated by microhardness measurements and conductometer Sigmatest, respectively. The prealloyed 5 h-milled and compacted powder showed a significant increase in microhardness reaching the value of 2600 MPa, about 4 times greater than that of compacts synthesized from as-received electrolytic copper powder (670 MPa). The electrical conductivity of compacts from 5 h-milled powder was 52% IACS. The results were discussed in terms of the effect of small grain size and finely distributed alumina dispersoids on hardening and thermal stability of compacts.

  10. Fluid mechanics of slurry flow through the grinding media in ball mills

    SciTech Connect

    Songfack, P.K.; Rajamani, R.K.

    1995-12-31

    The slurry transport within the ball mill greatly influences the mill holdup, residence time, breakage rate, and hence the power draw and the particle size distribution of the mill product. However, residence-time distribution and holdup in industrial mills could not be predicted a priori. Indeed, it is impossible to determine the slurry loading in continuously operating mills by direct measurement, especially in industrial mills. In this paper, the slurry transport problem is solved using the principles of fluid mechanics. First, the motion of the ball charge and its expansion are predicted by a technique called discrete element method. Then the slurry flow through the porous ball charge is tackled with a fluid-flow technique called the marker and cell method. This may be the only numerical technique capable of tracking the slurry free surface as it fluctuates with the motion of the ball charge. The result is a prediction of the slurry profile in both the radial and axial directions. Hence, it leads to the detailed description of slurry mass and ball charge within the mill. The model predictions are verified with pilot-scale experimental work. This novel approach based on the physics of fluid flow is devoid of any empiricism. It is shown that the holdup of industrial mills at a given feed percent solids can be predicted successfully.

  11. Curie temperature and magnetic properties of aluminum doped barium ferrite particles prepared by ball mill method

    NASA Astrophysics Data System (ADS)

    Chen, Daming; Harward, Ian; Baptist, Joshua; Goldman, Sara; Celinski, Zbigniew

    2015-12-01

    Barium ferrite has attracted considerable interest in the fields of permanent magnets and perpendicular magnetic recording due to its strong uniaxial anisotropy and high Curie temperature (Tc). We prepared aluminum doped barium ferrite ceramics (BaAlxFe12-xO19, 0≤x≤6) by the ball mill method. The powder was milled for 96 h, and after forming pellets, annealed for 48 h in air at 1000 °C. The X-ray diffraction (XRD) data show that there are only single hexagonal phases in the samples without any impurity phase. The crystal lattice constants, a and c, were calculated by Cohen's method. Both a and c decrease with increasing x, ranging from 0.588 nm and 2.318 nm to 0.573 nm and 2.294 nm, respectively. A Vibrating Sample Magnetometer (VSM) and Superconducting Quantum Interference Device (SQUID) were used to investigate Tc and magnetic properties of BaFe12-xAlxO19. It is found that Tc decreases with increasing x, from 425 °C to 298 °C. It is also found that the saturated magnetization (4πMs) decreases with increasing x, while the coercivity (Hc) increases with the increase in x. The anisotropy field was also determined from the SQUID measurement.

  12. Combined pretreatment using ozonolysis and ball milling to improve enzymatic saccharification of corn straw.

    PubMed

    Shi, Feng; Xiang, Heji; Li, Yongfu

    2015-03-01

    Two clean pretreatments, ozonolysis (OZ) and planetary ball milling (BM) were applied separately and in combination to improve the enzymatic hydrolysis of corn straw. Pretreatment of corn straw by OZ and BM alone improved the enzymatic hydrolysis significantly, primarily through delignification and decrystallization of cellulose, respectively. When combined, OZ-BM and BM-OZ pretreatments made the enzymatic hydrolysis more efficient. The glucose and xylose yield of corn straw treated with OZ for 90 min followed by BM for 8 min (OZ90-BM8) reached to 407.8 and 101.9 mg/g-straw, respectively under cellulase loading of 15 FPU/g-straw, which was fivefold more than that of untreated straw. Under much lower cellulase loading of 1.5 FPU/g-straw, the glucose and xylose yield of treated straw OZ90-BM8 remained at 416.0 and 108.4 mg/g-straw, respectively, while the yield of untreated straw decreased. These findings indicate that the combined OZ-BM can be used as a promising pretreatment for corn straw.

  13. Surface modification of calcined kaolin with toluene diisocyanate based on high energy ball milling

    NASA Astrophysics Data System (ADS)

    Yuan, Yongbing; Chen, Hongling; Lin, Jinbin; Ji, Yan

    2013-11-01

    The surface of calcined kaolin particle was modified with toluene diisocyanate (TDI) by using high energy ball milling. The prepared hybrids were characterized by FT-IR, MAS NMR, thermal analysis (TGA-DSC), static water contact angle (CA), apparent viscosity and transmission electron microscopy (TEM). FT-IR and MAS NMR spectra demonstrated that TDI molecules were chemically anchored to kaolin surface after modification. The results of thermal analysis showed that the maximum grafting ratio reached up to 446.61% when the mass ratio of TDI/kaolin was 0.5:1.0, and CA measurements revealed that the resultant hybrids exhibited strong hydrophobicity (148.82°). Apparent viscosity and TEM were employed to examine the dispersion properties of blank and modified kaolin particles in poly (dimenthylsiloxane) matrix. The results illustrated that the dispersion stability depended strongly on the grafting ratio of TDI, neither too low nor too high achieved uniform and stable dispersion, and the favorable grafting ratio was obtained when the mass ratio of TDI/kaolin was 0.2:1.0. Further modification of TDI/kaolin (mass ration of TDI/kaolin, 1.0:1.0) particles with bis(aminopropyl)-terminated-poly(dimethylsiloxane) (APS) was also investigated. TEM evidenced that the dispersion properties of the obtained TDI/APS/kaolin particles were remarkably improved in octamethyl cyclotetrasiloxane compared with the original TDI/kaolin particles.

  14. Evaluation of hydrogenation properties on MgHx-transition metal fluoride composites by planetary ball milling

    NASA Astrophysics Data System (ADS)

    Jang, Min-Hyuk; Park, So-Hyun; Kim, Whan-Gi; Hong, Tae-Whan

    2015-11-01

    To improve the disadvantages of Mg hydrides, a few studies were conducted for MgHx intermixed with transition metal fluorides. MgF2 formed from the MgHx-transition metal fluoride system can be replaces the initial surface oxide layer and provides a reactive and protective fluorinated surface for for hydrogen uptake. Thus, the absorption/desorption kinetics will be enhanced. In this research, MgHx-transition metal fluoride composites mixture has been prepared by hydrogen induced planetary ball milling. The synthesized powders were characterized by X-ray diffraction analysis, scanning electron microscopy and simultaneous thermogravimetric, differential scanning calorimetric analysis. The hydrogenation behaviors were evaluated by using a sievert's type automatic pressure-composition-temperature apparatus without any activation treatment. From the characteristics of the absorption kinetics and curves observed, the role of transition metal fluoride was catalyst in hydrogen absorption. The results of Pressure-Composition Isotherm curve, available hydrogen storage amount for MgHx-5 vol% CoF2 composites were 4.85 wt%, for MgHx-5 vol%TiF3 composites were 4.88 wt%. at 623K in the 5th cycle.

  15. Insertion compounds and composites made by ball milling for advanced sodium-ion batteries.

    PubMed

    Zhang, Biao; Dugas, Romain; Rousse, Gwenaelle; Rozier, Patrick; Abakumov, Artem M; Tarascon, Jean-Marie

    2016-01-18

    Sodium-ion batteries have been considered as potential candidates for stationary energy storage because of the low cost and wide availability of Na sources. However, their future commercialization depends critically on control over the solid electrolyte interface formation, as well as the degree of sodiation at the positive electrode. Here we report an easily scalable ball milling approach, which relies on the use of metallic sodium, to prepare a variety of sodium-based alloys, insertion layered oxides and polyanionic compounds having sodium in excess such as the Na4V2(PO4)2F3 phase. The practical benefits of preparing sodium-enriched positive electrodes as reservoirs to compensate for sodium loss during solid electrolyte interphase formation are demonstrated by assembling full C/P'2-Na1[Fe0.5Mn0.5]O2 and C/'Na3+xV2(PO4)2F3' sodium-ion cells that show substantial increases (>10%) in energy storage density. Our findings may offer electrode design principles for accelerating the development of the sodium-ion technology.

  16. Influence of ball milling on the particle size and antimicrobial properties of Tridax procumbens leaf nanoparticles.

    PubMed

    Karthik, Subramani; Suriyaprabha, Rangaraj; Balu, Kolathupalayam Shanmugam; Manivasakan, Palanisamy; Rajendran, Venkatachalam

    2017-02-01

    The herbal nanoparticles were prepared from shade dried Tridax procumbens plant leaves employing ball milling technique using different process parameters, like ball ratio/size and milling time. The obtained nanoparticles were comprehensively characterised using X-ray diffraction, Fourier transform infrared spectroscopy, UV-visible spectroscopy, dynamic light scattering, scanning electron microscopy and antimicrobial analysis techniques. The crystallinity of the nanoparticles was retained without altering even though the particle size changes due to milling periods. The antibacterial activities of the prepared herbal nanoparticles against Staphylococcus aureus and Escherichia coli were explored to understand the influence of particle size on antimicrobial activities and their functional properties. The increase in ball ratio and milling time periods leads to a decrease in nanoparticle size from 114 to 45 nm which in turn increases the antimicrobial activities. The above study confirms that antimicrobial activity relies on nanoparticle size. The observed knowledge on influence of particle size on antimicrobial activities will help to optimise the production of potential herbal nanoparticles for different biomedical applications.

  17. Catalytic hydrodechlorination of monochloroacetic acid in wastewater using Ni-Fe bimetal prepared by ball milling.

    PubMed

    Zhu, Hong; Xu, Fuyuan; Zhao, Jianzhuang; Jia, Linfang; Wu, Kunming

    2015-09-01

    Monochloroacetic acid (MCA) is a chemically stable and biologically toxic pollutant. It is often generated during the production of the pesticide dimethoate. Conventional wastewater treatment processes have difficulty degrading it. In this work, the dechlorination effects of Ni-Fe bimetal prepared using ball milling (BM) technology for the high concentrations of MCA in wastewater were examined. The MCA in aqueous solution was found to be degraded efficiently by the Ni-Fe bimetal. However, S-(methoxycarbonyl) methyl O, O-dimethyl phosphorodithioate (SMOPD) in wastewater, a by-product of the dimethoate production process, significantly inhibited the reductive dechlorination activity of Ni-Fe bimetal. Increasing the reaction temperature in the MCA wastewater enhanced the reduction activity of the Ni-Fe bimetal effectively. Oxygen was found to be unfavorable to dechlorination. Sealing the reaction to prevent oxidation was found to render the degradation process more efficient. The process retained over 88% efficiency after 10 treatment cycles with 50 g/L of Ni-Fe bimetal under field conditions.

  18. Iron Nanoparticles Fabricated by High-Energy Ball Milling for Magnetic Hyperthermia

    NASA Astrophysics Data System (ADS)

    Tung, D. K.; Manh, D. H.; Phong, L. T. H.; Nam, P. H.; Nam, D. N. H.; Anh, N. T. N.; Nong, H. T. T.; Phan, M. H.; Phuc, N. X.

    2016-05-01

    Iron nanoparticles (FeNPs) have been successfully prepared by high-energy ball milling in air for various milling times from 1 h to 32 h. Their structure, particle size, elemental composition, magnetic, and inductive heating properties were investigated by means of x-ray diffraction (XRD) analysis, field-emission scanning electron microscopy, energy-dispersive x-ray (EDX) spectroscopy, vibrating-sample magnetometry, and magnetic induction heating, respectively. XRD analysis showed that the average crystallite size decreased to 11 nm after 10 h of milling, then remained almost unchanged for longer milling times. Coexistence of iron (Fe) and iron oxide (FeO) phases was detected after 12 h of milling. EDX analysis also confirmed the occurrence of oxidation, which can be reconciled with the corresponding decrease and increase in saturation magnetization ( M s) with milling time when exposed to oxygen and when annealed under H2 ambient due to oxygen reduction. The time-dependent magnetic and inductive heating responses of the FeNPs were investigated for prospective application in magnetic hyperthermia. The effect of varying the alternating-current (AC) magnetic field strength on the saturation heating temperature and specific loss power of FeNP-containing ferrofluid with concentration of 4 mg/mL was also studied and is discussed.

  19. Anisotropic SmCo{sub 5} nanoflakes by surfactant-assisted high energy ball milling

    SciTech Connect

    Cui, B. Z.; Gabay, A. M.; Li, W. F.; Hadjipanayis, G. C.; Marinescu, M.; Liu, J. F.

    2010-05-15

    Crystallographically anisotropic SmCo{sub 5} nanoflakes were fabricated directly by one-step surfactant-assisted high energy ball milling (HEBM) of Sm{sub 17}Co{sub 83} ingot powders for 5 h in heptane and oleic acid (OA) without preprocessing or further annealing. The SmCo{sub 5} nanoflakes have a strong [001] out-of-plane texture. The thickness of nanoflakes is in the range of 8-80 nm while their length is 0.5-8 {mu}m. The surfactant OA plays an important role in the formation of SmCo{sub 5} nanoflakes. HEBM of SmCo{sub 5} ingots in heptane without OA resulted in the formation of magnetically isotropic more or less equiaxed SmCo{sub 5} particles with a size of 2-30 {mu}m. Closely packed 'kebablike' SmCo{sub 5} nanoflakes were formed by HEBM in heptane with 15 wt % OA. HEBM in 150 wt % OA led to well-separated nanoflakes instead of the closely packed kebablike nanostructure. This resulted in the enhanced [001] out-of-plane texture. In-plane transmission electron microscope examination showed that the SmCo{sub 5} nanoflakes were composed of grains with sizes in the range of 4-8 nm. Coercivities of about 18.0 kOe were obtained for the anisotropic SmCo{sub 5} nanoflakes.

  20. Carbon Nanotube-Reinforced Aluminum Matrix Composites Produced by High-Energy Ball Milling

    NASA Astrophysics Data System (ADS)

    Travessa, Dilermando N.; da Rocha, Geovana V. B.; Cardoso, Kátia R.; Lieblich, Marcela

    2017-05-01

    Although multiwall carbon nanotubes (MWCNT) are promising materials to strengthen lightweight aluminum matrix composites, their dispersion into the metallic matrix is challenge. In the present work, MWCNT were dispersed into age-hardenable AA6061 aluminum alloy by high-energy ball milling and the blend was subsequently hot-extruded. The composite bars obtained were heat-treated by solution heat treatment at 520 °C and artificially aged at 177 °C for 8 h, in order to reach the T6 temper. Special attention was given to the integrity of the MWCNT along the entire composite production. The microstructure of the obtained bars was evaluated by optical and scanning electron microscopy, and the mechanical properties were evaluated by Vickers microhardness tests. Raman spectroscopy, x-ray diffraction and transmission electron microscopy were employed to evaluate the structural integrity of MWCNT. It was found that milling time is critical to reach a proper dispersion of the reinforcing phase. The composite hardness increased up to 67% with the dispersion of 2% in weight of MWCNT, when comparing with un-reinforced bars produced by similar route. However, age hardening was not observed in composite bars after heat treatment. It was also found that MWCNT continuously degraded along the process, being partially converted into Al4C3 in the final composite.

  1. Structural Investigations of Nanocrystalline Cu-Cr-Mo Alloy Prepared by High-Energy Ball Milling

    NASA Astrophysics Data System (ADS)

    Kumar, Avanish; Pradhan, Sunil Kumar; Jayasankar, Kalidoss; Debata, Mayadhar; Sharma, Rajendra Kumar; Mandal, Animesh

    2017-02-01

    Cu-Cr-Mo alloy could be a suitable candidate material for collector electrodes in high-power microwave tube devices. An attempt has been made to synthesize ternary Cu-Cr-Mo alloys by mechanical alloying of elemental Cu, Cr, and Mo powders, to extend the solid solubility of Cr and Mo in Cu, using a commercial planetary ball mill. For the first ternary alloy, a mixture of 80 wt.% Cu, 10 wt.% Cr, and 10 wt.% Mo was mechanically milled for 50 h. For the second ternary alloy, a mixture of 50 wt.% Cr and 50 wt.% Mo was mechanically milled for 50 h to obtain nanocrystalline Cr(Mo) alloy, which was later added to Cu powder and milled for 40 h to obtain Cu-20 wt.%Cr(Mo) alloy. Both nanocrystalline Cu-Cr-Mo ternary alloys exhibited crystallite size below 20 nm. It was concluded that, with addition of nanocrystalline Cr(Mo) to Cu, it was possible to extend the solid solubility of Cr and Mo in Cu, which otherwise was not possible by mechanical alloying of elemental powders. The resulting microstructure of the Cu-20 wt.%Cr(Mo) alloy comprised a homogeneous distribution of fine and hard (Cr, Mo) particles in a copper matrix. Furthermore, Cu-20 wt.%Cr(Mo) alloy showed better densification compared with Cu-10 wt.%Cr-10 wt.%Mo alloy.

  2. Electrochemical and interfacial properties of (PEO)10LiCF3SO3-Al2O3 nanocomposite polymer electrolytes using ball milling

    NASA Astrophysics Data System (ADS)

    Shin, J. H.; Jung, B. S.; Jeong, S. S.; Kim, K. W.; Ahn, H. J.; Cho, K. K.; Ahn, J. H.

    2004-04-01

    Electrochemical and interfacial properties of (PEO)10LiCF3SO3-Al2O3 composite polymer electrolytes (CPEs) prepared by either ball milling or stirring are reported. Ball milling was introduced into a slurry preparative technique utilizing PEO, lithium salt and Al2O3 powder ranging from 5 to 15 wt.%. The ionic conductivity was increased by ball milling over a range of temperatures. In particular, a significant increase at low temperature below the melting point of crystalline PEO was observed. Interfacial stability between lithium electrode and CPE was significantly improved by the addition of alumina as well as by ball milling. The electrochemical stability window produced by (PEO)10LiCF3SO3-Al2O3 ball milling was higher than that of stirring, which was about 4.4 V. Charge/discharge performance of Li/CPE/S cells with (PEO)10LiCF3SO3-Al2O3-12 hr ball milling was superior to that of a pristine polymer electrolyte due to the low interface resistance and high ionic conductivity.

  3. Ball-milled CuPc/TiO{sub 2} hybrid nanocomposite and its photocatalytic degradation of aqueous Rhodamine B

    SciTech Connect

    Mekprasart, W.; Vittayakorn, N.; Pecharapa, W.

    2012-11-15

    Graphical abstract: This work reports on the synthesis of hybrid composites of titanium dioxide and copper phthalocyanine via ball-milling assisted process in combination with mechanical mixing process. Their structural properties and photocatalytic degradation of aqueous RhB were investigated. The significant enhancement of the photocatalytic performance of the composite may be related to the charge recombination suppression guiding to the increase of free functional radicals participated in degradation process. Highlights: ► CuPc/TiO{sub 2} nanocomposite was synthesized by ball-milling assisted process and mechanical mixing method. ► Ball milling process can reduce CuPc size and assist the formation of well-dispersed composite. ► Loaded CuPc has inconsiderable influence on basic crystal structure of TiO{sub 2} matrix. ► The optical absorption properties of TiO{sub 2} in UV and visible light is improved with the existence of CuPc. ► CuPc/TiO{sub 2} nanocomposite can efficiently heighten the catalytic performance of TiO{sub 2} in the photodegradation of RhB. -- Abstract: Hybrid composites of titanium dioxide and copper phthalocyanine were synthesized by ball-milling assisted process in combination with mechanically stirring method. Structural properties of as-synthesized composites were characterized by X-ray diffraction (XRD), X-ray absorption fine structure (XANES) and scanning electron microscope (SEM). The optical absorbance of as-prepared composites and their photocatalytic activities were investigated by UV–vis spectroscopy. XRD and XANES results confirm that CuPc/TiO{sub 2} nanocomposite is still in the same structure of TiO{sub 2} and CuPc. SEM result reveals that the decreasing particle size of ball-milled CuPc has good dispersion on the surface of TiO{sub 2}. Absorptivity in UV region of the composites is heightened and shifted to visible light due to strong absorbance in blue-green spectrum of CuPc. The photocatalytic degradation of Rhodamine

  4. Reactive Ball Milling to Fabricate Nanocrystalline Titanium Nitride Powders and Their Subsequent Consolidation Using SPS

    NASA Astrophysics Data System (ADS)

    El-Eskandarany, M. Sherif

    2017-05-01

    The room-temperature reactive ball milling (RBM) approach was employed to synthesize nanostructured fcc-titanium nitride (TiN) powders, starting from milling hcp-titanium (Ti) powders under 10 bar of a nitrogen gas atmosphere, using a roller mill. During the first and intermediate stage of milling, the agglomerated Ti powders were continuously disintegrated into smaller particles with fresh surfaces. Increasing the RBM time led to an increase in the active-fresh surfaces of Ti, resulting increasing of the mole fraction of TiN against unreacted hcp-Ti. Toward the end of the RBM time (20 h), ultrafine spherical powder (with particles 0.5 μm in diameter) of the fcc-TiN phase was obtained, composed of nanocrystalline grains with an average diameter of 8 nm. The samples obtained after different stages of RBM time were consolidated under vacuum at 1600 °C into cylindrical bulk compacts of 20 mm diameter, using spark plasma sintering technique. These compacts that maintained their nanocrystalline characteristics with an average grain size of 56 nm in diameter, possessed high relative density (above 99% of the theoretical density). The Vickers hardness of the as-consolidated TiN was measured and found to be 22.9 GPa. The modulus of elasticity and shear modulus of bulk TiN were measured by a nondestructive test and found to be 384 and 189 GPa, respectively. In addition, the coefficient of friction of the end-product TiN bulk sample was measured and found to be 0.35.

  5. Solid state amorphization of Fe- and Co-based alloys and their magnetic properties

    NASA Astrophysics Data System (ADS)

    Tanaka, Satoshi; Diao, Zitao; Sugimoto, Toshiharu; Narita, Kenji

    1992-07-01

    Magnetic powders of FeSiB and CoFeSiB were prepared using a rotational or vibrational ball-mill. The characterization of the magnetic powders was mainly done by DTA and VSM. FeSiB powders were found not to become amorphous. However, CoFeSiB powders may be considered to become partially amorphous.

  6. EXAFS Studies and Microwave Magnetic Properties of FeGaB Thin Films and FeCuZr Ball-Milled Alloys

    NASA Astrophysics Data System (ADS)

    Gao, Jinsheng

    X-ray absorption fine structure (XAFS) is a spectroscopic technique which can investigate the physical and chemical structure of materials at the atomic scale. X-rays are applied in this technique to be near and above the binding energy of a particular core electronic level of a particular atomic species. Over the last decades, XAFS has emerged as a highly informative probe of the local structure around selected atomic species in solids, liquids, and molecular gases. It offers both element specificity and local structure sensitivity. Foremost among its strengths are its ability to probe the local atomic environments of different elements in the sample by selecting the corresponding incident X-ray energy. In the first part of this thesis, FeGaB alloys, which are of value as soft magnetic materials having relatively large magnetostriction coefficient, were fabricated in which varying amounts of boron were added to the host FeGa alloy to investigate its impact upon local atomic structure and magnetic and microwave properties. The impact of B upon the local atomic structure in FeGaB films were investigated by extended X-ray absorption fine structure (EXAFS) analysis. EXAFS fitting results revealed a contraction of lattice parameters with the introduction of B. The Debye-Waller factor determined from EXAFS fitting gradually increases as a function of boron addition and abruptly increases during the structural evolution from crystalline to amorphous. Upon the onset of this transition the static and microwave magnetic properties became exceptionally softer, with values of coercivity and ferromagnetic linewidth reducing dramatically. In the second part of this thesis, metastable alloys of the composition FeCuZr were synthesized by high energy ball milling and measured by EXAFS . The fitting results demonstrate that nanocrystalline or amorphous alloys have been obtained depending on the Zr content.

  7. Synthesis of Highly Active Mg-BASED Hydrides Using Hydriding Combustion Synthesis and NbF5 Additives

    NASA Astrophysics Data System (ADS)

    Chourashiya, M. G.; Park, C. N.; Park, C. J.

    2012-09-01

    Superiority of the hydriding combustion (HC) technique over conventional metallurgical approach to the synthesis of cost-effective Mg based hydrides, which show promise as hydrogen storage materials, is well known. In the present research, we report further improvements in HC prepared Mg-based materials, achieved by optimizing the preparative parameters of HC and by catalytic addition. Mg90-Ni60-C40 composites prepared using optimized processing parameters were ball-milled with NbF5 (10 h) and characterized for their micro-structural and hydriding properties. The ball-milled/catalyzed powder showed decreased crystallinity with CNTs on its surfaces. Surface area of the ball-milled powder decreased to almost half of the as-HC powder, while TG analysis revealed a four-fold decrease in the desorption temperature of the milled powder compared to that of the as-HC prepared powder. Activated samples achieved the maximum absorption/desorption limits (5.3 wt.%) at as low as 100°C, underlining the possibility of the use of these materials in portable hydrogen storage devices.

  8. Study of morphology and magnetic properties of the HoNi{sub 3} crystalline and ball-milled compound

    SciTech Connect

    Bajorek, Anna; Skornia, Paweł; Prusik, Krystian; Wojtyniak, Marcin; Chełkowska, Grażyna

    2015-03-15

    The morphology and magnetic properties of the HoNi{sub 3} crystalline and ball-milled intermetallic compounds are presented. The polycrystalline HoNi{sub 3} bulk compound crystallizes in the rhombohedral PuNi{sub 3} — type of crystal structure and indicates ferrimagnetic arrangement with the Curie temperature of T{sub C} = 57 ± 2 K, the helimagnetic temperature T{sub h} = 23 ± 2 K with the total saturation magnetic moment of 6.84 μ{sub B}/f.u. at 2 K. The use of the ball-milling method leads to the formation of HoNi{sub 3} nanoflakes with typical thickness of less than 100 nm prone to agglomeration upon milling. The increase of grinding duration leads to the reduction in crystallite size, which was confirmed by various complementary microscopical and diffraction studies. Moreover, the increase in milling duration results in the emergence of the relatively small coercivity (H{sub C}), remanence (M{sub r}) and a variation of the saturation magnetization (M{sub S}). - Graphical abstract: Display Omitted - Highlights: • The ball-milling method exhibits significant potential for producing RT{sub 3} nanopowders. • The AFM method was used for the first time in analysis of R–T nanoflakes morphology. • HoNi{sub 3} compound forms polycrystalline and textured nanoflakes evolving upon milling. • The decrease in crystallite size via grinding is confirmed by XRD, TEM and AFM. • The magnetic parameters were sensitive to the extension of pulverization b.

  9. Mechanochemical Rhodium(III)-Catalyzed C-H Bond Functionalization of Acetanilides under Solventless Conditions in a Ball Mill.

    PubMed

    Hermann, Gary N; Becker, Peter; Bolm, Carsten

    2015-06-15

    In a proof-of-principle study, a planetary ball mill was applied to rhodium(III)-catalyzed C-H bond functionalization. Under solventless conditions and in the presence of a minute amount of Cu(OAc)2, the mechanochemical activation led to the formation of an active rhodium species, thus enabling an oxidative Heck-type cross-coupling reaction with dioxygen as the terminal oxidant. The absence of an organic solvent, the avoidance of a high reaction temperature, the possibility of minimizing the amount of the metallic mediator, and the simplicity of the protocol result in a powerful and environmentally benign alternative to the common solution-based standard protocol.

  10. X-ray diffraction study of W-B elemental powder mixtures after high-energy ball-milling.

    NASA Astrophysics Data System (ADS)

    Stubičar, Mirko; Tonejc, Antun; Stubičar, Nada

    Very high temperatures are needed to prepare W-B compounds. However, the results obtained in this study demonstrate a possibility of inducing the formation of W2B, WB or WB4 tungsten borides, in air and at room temperature, using the high-energy ball-mill treatment on appropriate compositions of the W-B elemental powder mixtures. The present results throw a new light on the synthesis of tungsten borides, and on the accuracy of the equilibrium W-B phase diagram.

  11. Microstructures, Mechanical Properties and Thermal Conductivities of W-0.5 wt.%TiC Alloys Prepared via Ball Milling and Wet Chemical Method

    NASA Astrophysics Data System (ADS)

    Lang, Shaoting; Yan, Qingzhi; Sun, Ningbo; Zhang, Xiaoxin; Ge, Changchun

    2017-10-01

    Two kinds of W-0.5 wt.%TiC alloys were prepared, one by ball milling and the other by the wet chemical method. For comparison, pure tungsten powders were chemically prepared and sintered by the same process. The microstructures, mechanical properties and thermal conductivities of the prepared samples were characterized. It has been found that the wet chemical method resulted in finer sizes and more uniform distribution of TiC particles in the sintered tungsten matrix than the ball milling method. The W-TiC alloy prepared by the wet chemical method achieved the highest bending strength (1065.72 MPa) among the samples. Further, it also exhibited obviously higher thermal conductivities in the temperature range of room temperature to 600°C than did the W-TiC alloy prepared by ball milling, but the differences in their thermal conductivities could be ignored in the range of 600-800°C.

  12. Influence of Ball-Milling Treatment of B Original Powder on the Phase Formation and Critical Current Density of Graphite Doped MgB

    NASA Astrophysics Data System (ADS)

    Su, Xiaocheng; Jiang, Qingguo; Zuo, Anying

    2014-10-01

    In present work, the sintering process and superconducting properties of graphite doped MgB prepared with milled B original powder were investigated. It is found that ball milling treatment of B original powder obviously suppresses the solid-solid reaction between Mg and B, whereas it enhances their liquid-solid reaction during the subsequent sintering process of these graphite doped MgB bulks. Ball milling treatment of B original powder can also promote C substitution for B sites in MgB crystal lattice in the graphite-doped samples, and thus obviously increase their values of at high fields. Moreover, ball milling also refines MgB grains, enhancing grain boundary pinning and at high fields.

  13. Facile and Cost-Effective Synthesis and Deposition of a YBCO Superconductor on Copper Substrates by High-Energy Ball Milling

    NASA Astrophysics Data System (ADS)

    Alami, Abdul Hai; Assad, Mhd Adel; Aokal, Camilia

    2016-12-01

    The article investigates the synthesis and deposition of YBCO on a copper substrate for various functional purposes. The superconductor is first prepared by mechanically alloying elemental components (yttrium, barium, and copper) for 50 hours in a high-energy ball mill with subsequent protocol of heat treatment in an oxygen-rich atmosphere to arrive at stoichiometric ratios of YBa2Cu3O7. The material is then deposited on a thin copper substrate also by ball milling under various parameters of rotational speed and deposition time to select the best and most homogenous substrate coverage. Atomic force microscopy has confirmed the desired results, and other microstructural, thermal, and electrical techniques are used to characterize the obtained material. High-energy ball milling proved to be a versatile means to synthesize and deposit the material in a straightforward manner and controllable parameters for different deposit thicknesses and coverages.

  14. Preparation of Si nano-crystals with controlled oxidation state from SiO disproportionated by ZrO2 ball-milling

    NASA Astrophysics Data System (ADS)

    Okamoto, Yuji; Harada, Yoshitomo; Ohta, Narumi; Takada, Kazunori; Sumiya, Masatomo

    2016-09-01

    We demonstrate that a SiO disproportionation reaction can be achieved simply by high energy mechanochemical milling. The planetary ball-milling of ZrO2 for a few minutes generated Si nano-crystals. Milling conditions including rotation speed, ball number, milling time, and type of ball material were able to control the oxidation states of Si. The ball-milled SiO powder was tested as an anode of a lithium battery. ZrO2 contamination from the vial and balls was eliminated by dipping the ball-milled SiO powder in (NH4)HSO4 molten salt and heating for 5 min. The disproportionated SiO powder showed characteristics comparable to those of a powder prepared by a conventional heating process taking several hours.

  15. Microstructures, Mechanical Properties and Thermal Conductivities of W-0.5 wt.%TiC Alloys Prepared via Ball Milling and Wet Chemical Method

    NASA Astrophysics Data System (ADS)

    Lang, Shaoting; Yan, Qingzhi; Sun, Ningbo; Zhang, Xiaoxin; Ge, Changchun

    2017-04-01

    Two kinds of W-0.5 wt.%TiC alloys were prepared, one by ball milling and the other by the wet chemical method. For comparison, pure tungsten powders were chemically prepared and sintered by the same process. The microstructures, mechanical properties and thermal conductivities of the prepared samples were characterized. It has been found that the wet chemical method resulted in finer sizes and more uniform distribution of TiC particles in the sintered tungsten matrix than the ball milling method. The W-TiC alloy prepared by the wet chemical method achieved the highest bending strength (1065.72 MPa) among the samples. Further, it also exhibited obviously higher thermal conductivities in the temperature range of room temperature to 600°C than did the W-TiC alloy prepared by ball milling, but the differences in their thermal conductivities could be ignored in the range of 600-800°C.

  16. Ball milled h-BN: an efficient holes transfer promoter to enhance the photocatalytic performance of TiO2.

    PubMed

    Fu, Xianliang; Hu, Yingfei; Yang, Yunguang; Liu, We; Chen, Shifu

    2013-01-15

    High activity hexagonal-BN (h-BN)/TiO(2) composite photocatalysts were prepared by ball milling method. The structural and optical properties of the samples were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), UV-vis diffuse reflectance spectra (DRS), and fluorescence emission spectra. The effect of the loading amount of h-BN and the ball milling time on the photocatalytic degradation of Rhodamine B (RhB) and methylene blue (MB) was investigated. The results indicated that the photocatalytic activity of TiO(2) could be improved substantially by coupling with a proper amount of milled h-BN. The optimal loading amount of h-BN was found to be 0.5 wt% and the milling time was 30 min. Under this condition, the photocatalytic removal efficiencies of TiO(2) for RhB and MB could be increased as high as 15 and 8 times. The role of the milling process and the mechanism for the enhancements was finally discussed in terms of creation of negatively charged h-BN surface and promotion the separation of photoinduced holes, respectively.

  17. Fast environment-friendly ball mill-assisted deep eutectic solvent-based extraction of natural products.

    PubMed

    Wang, Man; Wang, Jiaqin; Zhang, Yue; Xia, Qian; Bi, Wentao; Yang, Xiaodi; Chen, David Da Yong

    2016-04-22

    A fast environment-friendly extraction method, ball mill-assisted deep eutectic solvent-based extraction, was used for the extraction of natural products from plants. In this study, tanshinones were selected as target compounds to evaluate the efficiency of the developed extraction method. Under the optimized experimental conditions, cryptotanshinone (0.176 mg/g), tanshinone I (0.181 mg/g), and tanshinone II A (0.421 mg/g) were extracted from Salvia miltiorrhiza Bunge, and the developed method was found to be greener, more efficient, and faster than conventional, environmentally harmful extraction methods such as methanol-based ultrasound-assisted extraction and heat reflux extraction. The analytical performances including recovery, reproducibility (RSD, n=5), correlation of determination (r(2)), and the limit of detection, with the ranges of 96.1-103.9%, 1.6-1.9%, 0.9973-0.9984, and 5-8 ng/mL, were respectively obtained. Application of ball mill-assisted deep eutectic solvent-based extraction may fundamentally shape the future development of extraction methods. Copyright © 2016 Elsevier B.V. All rights reserved.

  18. Preparation of natural pyrite nanoparticles by high energy planetary ball milling as a nanocatalyst for heterogeneous Fenton process

    NASA Astrophysics Data System (ADS)

    Fathinia, Siavash; Fathinia, Mehrangiz; Rahmani, Ali Akbar; Khataee, Alireza

    2015-02-01

    In the present study pyrite nanoparticles were prepared by high energy mechanical ball milling utilizing a planetary ball mill. Various pyrite samples were produced by changing the milling time from 2 h to 6 h, in the constant milling speed of 320 rpm. X-ray diffraction (XRD), scanning electron microscopy (SEM) linked with energy dispersive X-ray (EDX), Fourier transform infrared spectroscopy (FT-IR) analysis and Brunauer-Emmett-Teller (BET) were performed to explain the characteristics of primary (unmilled) and milled pyrite samples. The average particle size distribution of the produced pyrite during 6 h milling was found to be between 20 nm and 100 nm. The catalytic performance of the different pyrite samples was examined in the heterogeneous Fenton process for degradation of C.I. Acid Orange 7 (AO7) solution. Results showed that the decolorization efficiency of AO7 in the presence of 6 h-milled pyrite sample was the highest. The impact of key parameters on the degradation efficiency of AO7 by pyrite nanoparticles catalyzed Fenton process was modeled using central composite design (CCD). Accordingly, the maximum removal efficiency of 96.30% was achieved at initial AO7 concentration of 16 mg/L, H2O2 concentration of 5 mmol/L, catalyst amount of 0.5 g/L and reaction time of 25 min.

  19. Selective ensemble modeling load parameters of ball mill based on multi-scale frequency spectral features and sphere criterion

    NASA Astrophysics Data System (ADS)

    Tang, Jian; Yu, Wen; Chai, Tianyou; Liu, Zhuo; Zhou, Xiaojie

    2016-01-01

    It is difficult to model multi-frequency signal, such as mechanical vibration and acoustic signals of wet ball mill in the mineral grinding process. In this paper, these signals are decomposed into multi-scale intrinsic mode functions (IMFs) by the empirical mode decomposition (EMD) technique. A new adaptive multi-scale spectral features selection approach based on sphere criterion (SC) is applied to these IMFs frequency spectra. The candidate sub-models are constructed by the partial least squares (PLS) with the selected features. Finally, the branch and bound based selective ensemble (BBSEN) algorithm is applied to select and combine these ensemble sub-models. This method can be easily extended to regression and classification problems with multi-time scale signal. We successfully apply this approach to a laboratory-scale ball mill. The shell vibration and acoustic signals are used to model mill load parameters. The experimental results demonstrate that this novel approach is more effective than the other modeling methods based on multi-scale frequency spectral features.

  20. Highly Al-doped TiO{sub 2} nanoparticles produced by Ball Mill Method: structural and electronic characterization

    SciTech Connect

    Santos, Desireé M. de los Navas, Javier Sánchez-Coronilla, Antonio; Alcántara, Rodrigo; Fernández-Lorenzo, Concha; Martín-Calleja, Joaquín

    2015-10-15

    Highlights: • Highly Al-doped TiO{sub 2} nanoparticles were synthesized using a Ball Mill Method. • Al doping delayed anatase to rutile phase transformation. • Al doping allow controlling the structural and electronic properties of nanoparticles. - Abstract: This study presents an easy method for synthesizing highly doped TiO{sub 2} nanoparticles. The Ball Mill method was used to synthesize pure and Al-doped titanium dioxide, with an atomic percentage up to 15.7 at.% Al/(Al + Ti). The samples were annealed at 773 K, 973 K and 1173 K, and characterized using ICP-AES, XRD, Raman spectroscopy, FT-IR, TG, STEM, XPS, and UV–vis spectroscopy. The effect of doping and the calcination temperature on the structure and properties of the nanoparticles were studied. The results show high levels of internal doping due to the substitution of Ti{sup 4+} ions by Al{sup 3+} in the TiO{sub 2} lattice. Furthermore, anatase to rutile transformation occurs at higher temperatures when the percentage of doping increases. Therefore, Al doping allows us to control the structural and electronic properties of the nanoparticle synthesized. So, it is possible to obtain nanoparticles with anatase as predominant phase in a higher range of temperature.

  1. Impact of high energy ball milling on the nanostructure of magnetite–graphite and magnetite–graphite–molybdenum disulphide blends

    SciTech Connect

    Österle, W.; Orts-Gil, G.; Gross, T.; Deutsch, C.; Hinrichs, R.; Vasconcellos, M.A.Z.; Zoz, H.; Yigit, D.; Sun, X.

    2013-12-15

    Different, partly complementary and partly redundant characterization methods were applied to study the transition of magnetite, graphite and MoS{sub 2} powders to mechanically alloyed nanostructures. The applied methods were: Transmission electron microscopy (TEM), Mössbauer spectroscopy (MS), Raman spectroscopy (RS), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The main objective was to prepare a model material providing the essential features of a typical tribofilm forming during automotive braking, and to assess the impact of different constituents on sliding behaviour and friction level. Irrespective of the initial grain size, the raw materials were transferred to a nanocrystalline structure and mixed on a nanoscopic scale during high energy ball milling. Whereas magnetite remained almost unchanged, graphite and molybdenum disulphide were transformed to a nanocrystalline and highly disordered structure. The observed increase of the coefficient of friction was attributed to a loss of lubricity of the latter ingredient due to this transformation and subsequent oxidation. - Highlights: • Characterization of microstructural changes induced by high energy ball milling • Assessment of the potential of different characterization methods • Impact of mechanical alloying on tribological performance revealed by tests • Preparation of an artificial third body resembling the one formed during braking.

  2. Synthesis of magnetically exchange coupled SrFe12O19/FeCo composites through cryogenic ball milling

    NASA Astrophysics Data System (ADS)

    Pang, Ning; Ye, Feng; Jiang, Ying

    2017-07-01

    SrFe12O19/FeCo composite particles with different mass ratios of SrFe12O19 to FeCo were synthesized through a cryogenic ball milling process. The corresponding products were characterized with scanning electron microscopy (SED), transmission electron microscopy (TEM), x-ray diffraction (XRD) and vibrating sample magnetometer (VSM) for crystal morphology, elemental distribution, crystal phases, and magnetic properties. The results showed that when the mass percentage of FeCo was less than 15%, smooth magnetic hysteresis loops could be obtained from SrFe12O19/FeCo composite particles, indicating effective magnetic exchange coupling between the SrFe12O19 and FeCo particles. A further FeCo mass increase resulted in kinks in the magnetic hysteresis loop and destroyed the magnetic exchange coupling. As a comparison, room temperature ball milling of SrFe12O19/FeCo (95/5 wt%) cannot achieve magnetic exchange coupling between SrFe12O19 and FeCo due to FeCo nanoparticle agglomeration.

  3. Effects of process control agent on the synthesis of AIN-carbon nanotube by ball-milling.

    PubMed

    Nam, Hye Rim; Kim, Young Jin; Ahn, Jung-Ho

    2013-09-01

    Aluminum and its alloy are of importance due to high specific strength. In particular, aluminum matrix composites have good corrosion resistance and mechanical property at high temperatures. However, enhanced mechanical strength and wear resistance via proper heat treatments are strongly required for many structural applications. For this purpose, we synthesized carbon nanotube (CNT)-reinforced aluminum matrix composites by employing a new method. We employed controlled ball-milling and sintering: the use of some specific process control agents (PCAs) for ball-milling and sintering in a specific atmosphere. The use of our PCAs was beneficial both for homogeneous mixing and for the formation of hard dispersoids. Hardened layers was formed at the surface of the present aluminum-CNT composites as a result of reaction of aluminum with PCAs and nitrogen in the processing atmosphere. The resulting materials after sintering showed interesting mechanical properties, combined with surface hardening. The hardening mainly stems from the formation of Al-N-O phase at the surface of specimens.

  4. Highly active and stable Ni-Fe bimetal prepared by ball milling for catalytic hydrodechlorination of 4-chlorophenol.

    PubMed

    Xu, Fuyuan; Deng, Shubo; Xu, Jie; Zhang, Wang; Wu, Min; Wang, Bin; Huang, Jun; Yu, Gang

    2012-04-17

    A novel Ni-Fe bimetal with high dechlorination activity for 4-chlorophenol (4-CP) was prepared by ball milling (BM) in this study. Increasing Ni content and milling time greatly enhanced the dechlorination activity, which was mainly attributed to the homogeneous distribution of Ni nanoparticles (50-100 nm) in bulk Fe visualized by scanning electron microscopy/energy dispersive X-ray spectrometry (SEM/EDS) with image mapping. In comparison with the Ni-Fe bimetal prepared by a chemical solution deposition (CSD) process, the ball milled Ni-Fe bimetal possessed high dechlorination activity and stability before being used up. Dechlorination kinetics indicated that the dechlorination rates of 4-CP increased with increasing Ni-Fe dose but decreased with increasing solution pH. Solution pH had a significant effect on the dechlorination of 4-CP and the passivation of the Ni-Fe bimetal. The enhanced pH during the dechlorination process significantly accelerated the formation of passivating film on the bimetallic surface. The Ni-Fe bimetal at the dose of 60 g/L was reused 10 times without losing dechlorination activity for 4-CP at initial pH less than 6.0, but the gradual passivation was observed at initial pH above 7.0.

  5. Synthesis of Nano-Size AlN Powders by Carbothermal Reduction from Plasma-Assisted Ball Milling Precursor

    NASA Astrophysics Data System (ADS)

    Liu, Zhijie; Wang, Wenchun; Yang, Dezheng; Wang, Sen; Dai, Leyang

    2016-07-01

    Nano-size aluminum nitride (AlN) powders have been successfully synthesized with a high efficiency method through annealing from milling assisted by discharge plasma (p-milling) alumina (Al2O3) precursors. The characterization of the p-milling Al2O3 powders and the synthesized AlN are investigated. Compared to conventional ball milling (c-milling), it can be found that the precursors by p-milling have a finer grain size with a higher specific surface area, which lead to a faster reaction efficiency and higher conversion to AlN at lower temperatures. The activation energy of p-milling Al2O3 is found to be 371.5 kJ/mol, a value that is much less than the reported value of the unmilled and the conventional milled Al2O3. Meanwhile, the synthesized AlN powders have unique features, such as an irregular lamp-like morphology with uniform particle distribution and fine average particle size. The results are attributed to the unique synergistic effect of p-milling, which is the effect of deformation, fracture, and cold welding of Al2O3 powders resulting from ball milling, that will be enhanced due to the introduction of discharge plasma. supported by National Natural Science Foundation of China (No. 51177008)

  6. Enhanced lithium storage in ZnFe2O4-C nanocomposite produced by a low-energy ball milling

    NASA Astrophysics Data System (ADS)

    Thankachan, Rahul Mundiyaniyil; Rahman, Md Mokhlesur; Sultana, Irin; Glushenkov, Alexey M.; Thomas, Sabu; Kalarikkal, Nandakumar; Chen, Ying

    2015-05-01

    Preparation of novel nanocomposite structure of ZnFe2O4-C is achieved by combining a sol-gel and a low energy ball milling method. The crucial feature of the composite's structure is that sol-gel synthesised ZnFe2O4 nanoparticles are dispersed and attached uniformly along the chains of Super P Li™ carbon black matrix by adopting a low energy ball milling. The composite ZnFe2O4-C electrodes are capable of delivering a very stable reversible capacity of 681 mAh g-1 (96% retention of the calculated theoretical capacity of ∼710 mAh g-1) at 0.1 C after 100 cycles with a remarkable Coulombic efficiency (82%) improvement in the first cycle. The rate capability of the composite is significantly improved and obtained capacity was as high as 702 at 0.1, 648 at 0.5, 582 at 1, 547 at 2 and 469 mAh g-1 at 4 C (2.85 A g-1), respectively. When cell is returned to 0.1 C, the capacity recovery was still ∼98%. Overall, the electrochemical performance (in terms of cycling stability, high rate capability, and capacity retention) is outstanding and much better than those of the related reported works. Therefore, our smart electrode design enables ZnFe2O4-C sample to be a high quality anode material for lithium-ion batteries.

  7. Discrete element method based scale-up model for material synthesis using ball milling

    NASA Astrophysics Data System (ADS)

    Santhanam, Priya Radhi

    Mechanical milling is a widely used technique for powder processing in various areas. In this work, a scale-up model for describing this ball milling process is developed. The thesis is a combination of experimental and modeling efforts. Initially, Discrete Element Model (DEM) is used to describe energy transfer from milling tools to the milled powder for shaker, planetary, and attritor mills. The rolling and static friction coefficients are determined experimentally. Computations predict a quasisteady rate of energy dissipation, E d, for each experimental configuration. It is proposed that the milling dose defined as a product of Ed and milling time, t, divided by the mass of milled powder, mp characterizes the milling progress independently of the milling device or milling conditions used. Once the milling dose is determined for one experimental configuration, it can be used to predict the milling time required to prepare the same material in any milling configuration, for which Ed is calculated. The concept is validated experimentally for DEM describing planetary and shaker mills. For attritor, the predicted Ed includes substantial contribution from milling tool interaction events with abnormally high forces (>103 N). The energy in such events is likely dissipated to heat or plastically deform milling tools rather than refine material. Indeed, DEM predictions for the attritor correlate with experiments when such events are ignored in the analysis. With an objective of obtaining real-time indicators of milling progress, power, torque, and rotation speed of the impeller of an attritor mill are measured during preparation of metal matrix composite powders in the subsequent portion of this thesis. Two material systems are selected and comparisons made between in-situ parameters and experimental milling progress indicators. It is established that real-time measurements can certainly be used to describe milling progress. However, they need to be interpreted carefully

  8. Effect of combination ultrasonic and ball milling techniques of commercial fillers dispersion on mechanical properties of natural rubber (NR) latex films

    NASA Astrophysics Data System (ADS)

    Hamran, Noramirah; Rashid, Azura A.

    2017-07-01

    Commercial fillers such as silica and carbon black generally impart the reinforcing effects in dry rubber compound, but have an adverse effect on Natural rubber (NR) latex compounds. The addition of commercial fillers in NR latex has reduced the mechanical properties of NR latex films due to the destabilization effect in the NR latex compounds which govern by the dispersion quality, particle size and also the pH of the dispersion itself. The ball milling process is the conventional meth od of preparation of dispersions and ultrasonic has successfully used in preparation of nano fillers such as carbon nanotube (CNT). In this study the combination between the conventional methods; ball milling together the ultrasonic method were used to prepare the silica and carbon black dispersions. The different duration of ball milling (24, 48 and 72 hours) was compared with the ultrasonic method (30, 60, 90 and 120 minutes). The combination of ball milling and ultrasonic from the optimum individual technique was used to investigate the reduction of particle size of the fillers. The particle size analyzer, transmission electron microscopy (TEM) and scanning electron microscopy (SEM) test were carried out to investigate the obtained particle size and the tensile and tear test were carried out to investigate the mechanical properties of the NR latex films. The reduction of filler particle size is expected to impart the properties of NR latex films.

  9. GEL-STATE NMR OF BALL-MILLED WHOLE CELL WALLS IN DMSO-d6 USING 2D SOLUTION-STATE NMR SPECTROSCOPY

    USDA-ARS?s Scientific Manuscript database

    Plant cell walls were used for obtaining 2D solution-state NMR spectra without actual solubilization or structural modification. Ball-milled whole cell walls were swelled directly in the NMR tube with DMSO-d6 where they formed a gel. There are relatively few gel-state NMR studies. Most have involved...

  10. Electric modulus formalism and electrical transport property of ball mill synthesized nanocrystalline Mn doped ZrO2 solid solution

    NASA Astrophysics Data System (ADS)

    Saha, S.; Nandy, A.; Meikap, A. K.; Pradhan, S. K.

    2015-12-01

    Here we report the formation of Mn doped nanocrystalline ZrO2 solid solution synthesized by high energy ball-milling method and the transport mechanism in the temperature range 298 K

  11. Superthermostability of nanoscale TIC-reinforced copper alloys manufactured by a two-step ball-milling process

    NASA Astrophysics Data System (ADS)

    Wang, Fenglin; Li, Yunping; Xu, Xiandong; Koizumi, Yuichiro; Yamanaka, Kenta; Bian, Huakang; Chiba, Akihiko

    2015-12-01

    A Cu-TiC alloy, with nanoscale TiC particles highly dispersed in the submicron-grained Cu matrix, was manufactured by a self-developed two-step ball-milling process on Cu, Ti and C powders. The thermostability of the composite was evaluated by high-temperature isothermal annealing treatments, with temperatures ranging from 727 to 1273 K. The semicoherent nanoscale TiC particles with Cu matrix, mainly located along the grain boundaries, were found to exhibit the promising trait of blocking grain boundary migrations, which leads to a super-stabilized microstructures up to approximately the melting point of copper (1223 K). Furthermore, the Cu-TiC alloys after annealing at 1323 K showed a slight decrease in Vickers hardness as well as the duplex microstructure due to selective grain growth, which were discussed in terms of hardness contributions from various mechanisms.

  12. Properties of dispersion-strengthened chromium - 4-volume-percent-thoria alloys produced by ball milling in hydrogen iodide

    NASA Technical Reports Server (NTRS)

    Arias, A.

    1974-01-01

    The effects of processing variables on the tensile properties and ductile-to-brittle transition temperature (DBTT) of Cr + 4 vol. %ThO2 alloys and of pure Cr produced by ball milling in hydrogen iodide were investigated. Hot rolled Cr + ThO2 was stronger than either hot pressed Cr + ThO2 or pure Cr at temperatures up to 1537 C. Hot pressed Cr + ThO2 had a DBTT of 501 C as compared with minus 8 to 24 C for the hot rolled Cr + ThO2 and with 139 C for pure Cr. It is postulated that the dispersoid in the hot rolled alloys lowers the DBTT by inhibiting recovery and recrystallization of the strained structure.

  13. Synthesis of graphene nanoflakes by grinding natural graphite together with NaCl in a planetary ball mill

    NASA Astrophysics Data System (ADS)

    Alinejad, Babak; Mahmoodi, Korosh

    Natural graphite is a soft material that conventional milling methods fail to grind into nanoparticles. We found that adding NaCl into graphite during milling allows obtaining graphene nanoflakes of about 50×200nm2 as evidenced by Transmission Electron Microscope (TEM). NaCl particles are substantially brittle and harder than graphite, serving as milling agents by both helping to chop graphite into smaller pieces and preventing graphite particles from agglomeration. After milling, NaCl can be easily washed away by water. Probable mechanism for exfoliation of graphene during the modified ball milling may be explained by NaCl and graphene slipping or sliding against and over each other, exfoliating the graphene particles into thin layers.

  14. High trapped fields in bulk MgB2 prepared by hot-pressing of ball-milled precursor powder

    NASA Astrophysics Data System (ADS)

    Fuchs, G.; Häßler, W.; Nenkov, K.; Scheiter, J.; Perner, O.; Handstein, A.; Kanai, T.; Schultz, L.; Holzapfel, B.

    2013-12-01

    Bulk superconducting MgB2 samples, 20 mm in diameter, were prepared by hot-pressing of ball-milled Mg and B powders using fine-grained boron powders. High maximum trapped fields of B0 = 5.4 T were obtained at 12 K in one of the investigated trapped field magnets (height 8 mm) at the centre of the bulk surface. Investigating the temperature dependence of the trapped field for short MgB2 samples (height ≤1.6 mm), trapped fields of up to B0 = 3.2 T at 15 K were achieved. These high trapped fields are related to extremely high critical current densities of up to 106 A cm-2 at 15 K, indicating strong pinning due to nanocrystalline MgB2 grains. Expected trapped field data for long trapped field magnets prepared from the available MgB2 material are estimated.

  15. Orange-red light emitting europium-doped calcium molybdate phosphor prepared by high-energy ball milling

    NASA Astrophysics Data System (ADS)

    Hong, Woo Tae; Lee, Joo Hyun; Park, Jin Young; Yang, Hyun Kyoung; Jeong, Jung Hyun; Moon, Byung Kee

    2016-09-01

    Europium-doped calcium molybdates (CaMoO4:Eu3+) were successfully synthesized by a high-energy ball milling method. The x-ray diffraction patterns confirmed their powellite structure, and the field emission scanning electron microscope image exhibited the spherical particles with submicron size. The photoluminescence (PL) properties of Eu3+ in these phosphors were also studied by analyzing the excitation and emission spectra for the effect of europium concentration. The CaMoO4:Eu3+ PL excitation and PL spectra show charge transfer band and several transition peaks correlated with host lattice band gap and f-f transitions of Eu3+, respectively. By sintering Ca0.95MoO4:0.05Eu3+ phosphor at 1200°C, PL intensity has a maximum value at 618 nm with Commision Internationale de I'Eclairage 1931 (CIE 1931) chromaticity coordinates (0.609, 0.343).

  16. Kinetics and Mechanisms of Phase Transformations Induced by Ball-Milling in Anatase TiO 2

    NASA Astrophysics Data System (ADS)

    Bégin-Colin, S.; Girot, T.; Le Caër, G.; Mocellin, A.

    2000-01-01

    Ball-milling is a way of inducing phase transformations, chemical reactions, and changes in the reactivity of solids. It is a complex process for which several models have been developed to predict the evolution of systems and to describe its physics. These models sometimes empirically need experimental data to be ascertained and to confirm general theories of system evolutions. In this work, we investigate the effect of two milling parameters, the powder to ball weight ratio R and the nature of the grinding media, on the kinetics of phase transformations in anatase TiO2 powder. These experiments established that R affects only the reaction rate. The kinetics are faster with alumina than with steel grinding tools for a given R, specific injected powers being similar. It has been demonstrated that the phase transformations induced by grinding TiO2 occur without fracturing of particles and mechanisms are commented upon.

  17. The structure and magnetic properties of Sm-Fe-N powders prepared by ball milling at low temperature

    NASA Astrophysics Data System (ADS)

    Fang, Qiuli; An, Xiaoxin; Wang, Fang; Li, Ying; Du, Juan; Xia, Weixing; Yan, Aru; Liu, J. Ping; Zhang, Jian

    2016-07-01

    Sm-Fe-N powders have great potential to be used for preparing high-performance bonded permanent magnets because of their high anisotropy field and large saturation magnetization. In this work, we report the morphology, structure, oxygen content and magnetic properties of the Sm-Fe-N powders prepared by high energy ball milling at low temperature. Compared with the samples milled at room temperature, the Sm-Fe-N powders prepared at low temperature display more homogeneous morphology, less decomposition, lower oxygen content, and therefore enhanced magnetic performance. Our experimental results indicate that the low temperature milling will be a promising method for fabricating Sm-Fe-N bonded magnets with high-performance.

  18. Dielectric and photocatalytic properties of sulfur doped TiO{sub 2} nanoparticles prepared by ball milling

    SciTech Connect

    Jalalah, Mohammed; Faisal, M.; Bouzid, Houcine; Ismail, Adel A.; Al-Sayari, Saleh A.

    2013-09-01

    Graphical abstract: - Highlights: • Designing of visible light responsive photocatalyst utilizing ball milling. • Sulphur used as dopant in commercial TiO{sub 2} P25 at different atomic percentage. • S doping resulted in an intense increase in absorption in the visible light region. • Newly design photocatalyst exhibited excellent photocatalytic performance. • 0.11 at.% S-doped TiO{sub 2} shows 3-times higher activity than that of TiO{sub 2} P25. - Abstract: Sulfur (S) doped commercial TiO{sub 2} P-25 has been achieved by changing the amount of thiourea using ball milling technique. The results of XRD clearly reveal biphasial anatase and rutile mixtures for all prepared samples and doping of S does not change the morphology of the TiO{sub 2}. The optical absorption edge of S-doped TiO{sub 2} was red shifted with indirect bandgap energy of 2.8 eV. The dielectric studies confirm that the dielectric constant of TiO{sub 2} increases after doping, however it becomes more conductive. Newly designed S-doped TiO{sub 2} photocatalysts exhibited excellent photocatalytic performance for the degradation of methylene blue (MB) under visible light. The overall photocatalytic activity of 0.11 at.% S-doped TiO{sub 2} was significantly 3-times higher than that of commercial TiO{sub 2} P-25 and complete degradation of MB has taken place after 90 min of irradiation under visible light while only 35% dye degraded when the reaction has been carried out in the presence of undoped TiO{sub 2}.

  19. Preparation of ultrafine magnetic biochar and activated carbon for pharmaceutical adsorption and subsequent degradation by ball milling

    PubMed Central

    Shan, Danna; Deng, Shubo; Zhao, Tianning; Wang, Bin; Wang, Yujue; Huang, Jun; Yu, Gang; Winglee, Judy; Wiesner, Mark R.

    2017-01-01

    Ball milling was used to prepare two ultrafine magnetic biochar/Fe3O4 and activated carbon (AC)/Fe3O4 hybrid materials targeted for use in pharmaceutical removal by adsorption and mechanochemical degradation of pharmaceutical compounds. Both hybrid adsorbents prepared after 2 hours milling exhibited high removal of carbamazepine (CBZ), and were easily separated magnetically. These adsorbents exhibited fast adsorption of CBZ and tetracycline (TC) in the initial 1 hour. The biochar/Fe3O4 had a maximum adsorption capacity of 62.7 mg/g for CBZ and 94.2 mg/g for TC, while values obtained for AC/Fe3O4 were 135.1 mg/g for CBZ and 45.3 mg/g for TC respectively when data were fitted using the Langmuir expression. Solution pH values slightly affected the sorption of TC on the adsorbents, while CBZ sorption was almost pH-independent. The spent adsorbents with adsorbed CBZ and TC were milled to degrade the adsorbed pollutants. The adsorbed TC itself was over 97% degraded after 3 hours of milling, while about half of adsorbed CBZ were remained. The addition of quartz sand was found to improve the mechanochemical degradation of CBZ on biochar/Fe3O4, and its degradation percent was up to 98.4% at the dose of 0.3 g quarts sand/g adsorbent. This research provided an easy method to prepare ultrafine magnetic adsorbents for the effective removal of typical pharmaceuticals from water or wastewater and degrade them using ball milling. PMID:26685062

  20. Sulfur-graphene nanostructured cathodes via ball-milling for high-performance lithium-sulfur batteries.

    PubMed

    Xu, Jiantie; Shui, Jianglan; Wang, Jianli; Wang, Min; Liu, Hua-Kun; Dou, Shi Xue; Jeon, In-Yup; Seo, Jeong-Min; Baek, Jong-Beom; Dai, Liming

    2014-10-28

    Although much progress has been made to develop high-performance lithium-sulfur batteries (LSBs), the reported physical or chemical routes to sulfur cathode materials are often multistep/complex and even involve environmentally hazardous reagents, and hence are infeasible for mass production. Here, we report a simple ball-milling technique to combine both the physical and chemical routes into a one-step process for low-cost, scalable, and eco-friendly production of graphene nanoplatelets (GnPs) edge-functionalized with sulfur (S-GnPs) as highly efficient LSB cathode materials of practical significance. LSBs based on the S-GnP cathode materials, produced by ball-milling 70 wt % sulfur and 30 wt % graphite, delivered a high initial reversible capacity of 1265.3 mAh g(-1) at 0.1 C in the voltage range of 1.5-3.0 V with an excellent rate capability, followed by a high reversible capacity of 966.1 mAh g(-1) at 2 C with a low capacity decay rate of 0.099% per cycle over 500 cycles, outperformed the current state-of-the-art cathode materials for LSBs. The observed excellent electrochemical performance can be attributed to a 3D "sandwich-like" structure of S-GnPs with an enhanced ionic conductivity and lithium insertion/extraction capacity during the discharge-charge process. Furthermore, a low-cost porous carbon paper pyrolyzed from common filter paper was inserted between the 0.7S-0.3GnP electrode and porous polypropylene film separator to reduce/eliminate the dissolution of physically adsorbed polysulfide into the electrolyte and subsequent cross-deposition on the anode, leading to further improved capacity and cycling stability.

  1. Significantly improved dehydrogenation of ball-milled MgH2 doped with CoFe2O4 nanoparticles

    NASA Astrophysics Data System (ADS)

    Shan, Jiawei; Li, Ping; Wan, Qi; Zhai, Fuqiang; Zhang, Jun; Li, Ziliang; Liu, Zhaojiang; Volinsky, Alex A.; Qu, Xuanhui

    2014-12-01

    CoFe2O4 nanoparticles are added to magnesium hydride (MgH2) by high-energy ball milling in order to improve its hydriding properties. The hydrogen storage properties and catalytic mechanism are investigated by pressure-composition-temperature (PCT), differential thermal analysis (DTA), X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). The nonisothermal desorption results show that the onset desorption temperature of the MgH2 + 7 mol% CoFe2O4 is 160 °C, which is 200 °C lower than of the as-received MgH2. The dehydrogenation process of the MgH2 doped with the CoFe2O4 nanoparticles includes two steps. DTA curves and XRD patterns reveal that a chemical reaction happens between MgH2 and CoFe2O4, forming the final products of the ternary combination, corresponding to Co3Fe7, MgO and Co. The onset desorption temperature of the ball-milled MgH2 doped with Co3Fe7, MgO and Co is about 260 °C, approximately 100 °C lower than the un-doped MgH2, demonstrating that the ternary combination (Co3Fe7, MgO, and Co) also has a great catalytic effect on the MgH2 hydrogen storage properties. It is also confirmed that the various methods of adding the ternary combination have different effects on the MgH2 hydriding-dehydriding process.

  2. Preparation of ultrafine magnetic biochar and activated carbon for pharmaceutical adsorption and subsequent degradation by ball milling.

    PubMed

    Shan, Danna; Deng, Shubo; Zhao, Tianning; Wang, Bin; Wang, Yujue; Huang, Jun; Yu, Gang; Winglee, Judy; Wiesner, Mark R

    2016-03-15

    Ball milling was used to prepare two ultrafine magnetic biochar/Fe3O4 and activated carbon (AC)/Fe3O4 hybrid materials targeted for use in pharmaceutical removal by adsorption and mechanochemical degradation of pharmaceutical compounds. Both hybrid adsorbents prepared after 2h milling exhibited high removal of carbamazepine (CBZ), and were easily separated magnetically. These adsorbents exhibited fast adsorption of CBZ and tetracycline (TC) in the initial 1h. The biochar/Fe3O4 had a maximum adsorption capacity of 62.7mg/g for CBZ and 94.2mg/g for TC, while values obtained for AC/Fe3O4 were 135.1mg/g for CBZ and 45.3mg/g for TC respectively when data were fitted using the Langmuir expression. Solution pH values slightly affected the sorption of TC on the adsorbents, while CBZ sorption was almost pH-independent. The spent adsorbents with adsorbed CBZ and TC were milled to degrade the adsorbed pollutants. The adsorbed TC itself was over 97% degraded after 3h of milling, while about half of adsorbed CBZ were remained. The addition of quartz sand was found to improve the mechanochemical degradation of CBZ on biochar/Fe3O4, and its degradation percent was up to 98.4% at the dose of 0.3g quarts sand/g adsorbent. This research provided an easy method to prepare ultrafine magnetic adsorbents for the effective removal of typical pharmaceuticals from water or wastewater and degrade them using ball milling.

  3. Preparation of bismuth telluride based thermoelectric nanomaterials via low-energy ball milling and their property characterizations

    NASA Astrophysics Data System (ADS)

    Robinson, Christopher A.

    Thermoelectric materials are able to convert energy between heat and electricity with no moving parts, making them very appealing for power generation purposes. This is particularly appealing since many forms of energy generation lose energy to waste heat. The Livermore National Laboratory estimates that up to 55% of the energy created in traditional power plants is lost through heat generation [1]. As greenhouse gas emissions become a more important issue, large sources of waste like this will need to be harnessed. Adoption of these materials has been limited due to the cost and efficiency of current technology. Bismuth telluride based alloys have a dimensionless figure of merit, a measure of efficiency, near one at room temperature, which makes it the best current material. In order to compete with other forms of energy generation, this needs to be increased to three or higher [2]. Recently, improvements in performance have come in the form of random nanostructured materials [3]. Bulk bismuth telluride is subjected to particle size reduction via high-energy ball milling in order to scatter phonons between grains. This reduces the lattice thermal conductivity which in turn increases the performance of the material. In this work, we investigate the use of low-energy ball milling as a method of creating nanoparticles of n-type and p-type Bi2Te3 alloys for thermoelectric applications. Optimization of parameters such as milling containers, milling media, contamination and milling time has resulted in creating 15nm particles of bismuth telluride alloys. After creating solid pellets of the resulting powders via hot pressing, the material's thermal and electrical conductivities as well as Seebeck coefficients were measured. The ZT of n-type Bi2Te2.7Se3 created using this method is 0.32, while the p-type Bi0.5Sb1.5Te3 exhibits a higher ZT of 1.24, both at room temperature.

  4. The influence of thermal and mechanical preparative techniques on the amorphous state of four poorly soluble compounds.

    PubMed

    Patterson, James E; James, Michael B; Forster, Angus H; Lancaster, Robert W; Butler, James M; Rades, Thomas

    2005-09-01

    A number of studies in the literature have reported on the use of different preparative techniques to convert crystalline pharmaceutical compounds into the amorphous form. However, very few direct comparisons of different preparative techniques using the same drugs are available. The purpose of this study was to determine the influence of two techniques: quench cooling and ball milling on four structurally diverse pharmaceutical drugs. Dipyridamole, carbamazepine, glibenclamide, and indomethacin were converted to the amorphous form by (a) quench cooling of the drug melt and (b) ball milling. The chemical purity and physical form of the products was determined using diffractometric, spectroscopic, and thermal analytical techniques. Products were analysed immediately post preparation and after storage under different stability conditions. Quench cooling of the melt resulted in amorphous conversion of all four compounds. However with glibenclamide, quench cooling resulted in unacceptable chemical degradation whereas ball milling of glibenclamide resulted in a change in the keto-enol tautomerism at the aryl amide moiety of this drug. Ball milling resulted in predominantly amorphous products for all compounds except carbamazepine. Ball milling of carbamazepine resulted in a polymorphic transition of the starting material to form III. Physical stability studies showed that irrespective of preparative technique and storage conditions all samples showed at least partial reversion to the crystalline state after storage. Quench cooling of drug melts may be of use as a preparative technique however it can result in chemical degradation. Ball milling may also be of use as a preparative technique however its effectiveness is dependent on the unit cell structure of the compound.

  5. Dependence of milling time on electrochemical properties of nano Si electrodes prepared by ball-milling.

    PubMed

    Cho, G B; Choi, S Y; Noh, J P; Jeon, Y M; Jung, K T; Nam, T H

    2011-07-01

    Morphology, crystallinity and electrochemical properties of Si powders fabricated by a mechanical milling process with milling time of 6-40 h were investigated by means of FESEM, XRD, Raman, TEM and cell test. Average size of Si powders was reduced to sub-micrometer scale after 10 h-milling and 40 nm-Si powders could be obtained at 48 h-milling. With increasing milling time, Si powders mostly changes from crystalline Si to amorphous one and the content of amorphous Si was increased. TEM result showed that a negligiable amount of crystalline Si remained even after 48 h-milling. Si electrode with 48 h-milled Si powders exhibited the best electrochemical properties in terms of capacity, efficiency and cycle performance: initial capacity of 3025 mAh g(-1), coulrombic efficiency of 79.4% and the capacity retention of 1000 mAh g(-1) (at 130 cycles). The good electrochemical properties of nano- and amorphous-Si are due to the high resistance against volume change and good reversibility of Li ion.

  6. Phase development during high-energy ball-milling of zinc oxide and iron - the impact of grain size on the source and the degree of contamination.

    PubMed

    Štefanić, G; Krehula, S; Štefanić, I

    2015-11-21

    High-energy ball-milling of powder mixtures of zincite (ZnO) and iron (α-Fe) at different weight ratios was performed in air using a planetary ball mill with a stainless steel milling assembly. Structural and microstructural changes during the ball-milling (up to 30 h) were monitored using X-ray powder diffraction, field emission scanning electron microscopy (FE-SEM) and UV-Vis diffuse reflectance spectroscopy. The mechanism of iron oxidation was determined from the results of Mössbauer spectroscopy. It was found that an early phase of ball-milling caused the oxidation of iron from Fe(0) to Fe(2+) followed by the formation of a solid solution structurally similar to wüstite. The wüstite-type phase rapidly disappeared upon prolonged milling, which was accompanied by further oxidation of iron from Fe(2+) to Fe(3+) and the formation of spinel-type ferrite structurally similar to franklinite (ZnFe2O4) in the products with a high zinc content, or magnetite (Fe3O4) in the products with a high iron content. Further milling or annealing had a low impact on the franklinite-type phase, but caused the transition of the magnetite-type phase to the phase structurally similar to hematite (α-Fe2O3). The results of energy dispersive X-ray spectrometry (EDS) showed a dramatic increase in the degree of contamination with the increase in the proportion of the starting iron (∼9 times higher contamination during the milling of pure iron compared with pure zincite). It was shown that the source of contamination (balls or vial) strongly depends on the type of milled sample. Ball-milling of relatively big and heavy grains (starting iron) caused preferential contamination from the vial whereas ball-milling of smaller and lighter grains (products obtained after prolonged milling) caused preferential contamination from the balls. After prolonged milling the contamination due to wear of the balls was dominant in all the products. An explanation for the observed impact of grain size on

  7. Investigation and characterization of ball-milled magnesium-based hydrides for hydrogen storage materials

    NASA Astrophysics Data System (ADS)

    Yang, Jing

    2011-12-01

    Three alloys are prepared through mechanical alloying and the hydrogen storage properties have been investigated systematically. In Mg-Ni and Mg-Ni-Fe alloys, the main binary alloy phase is Mg2Ni, while in Mg-Ni-Fe-Ti alloys, NiTi, FeTi are also found as the main binary phases beside Mg 2Ni. The hydrogen absorption capacities of the three alloys are 2.9wt%, 2.2wt% and 2.3wt% respectively. Absorption content increases with the increasing of milling time, which also increases the amorphous degree of the alloys. The amorphous degree increasing is unfavorable to improve hydrogen storage capacity. Longer milling time will contribute to a higher hydriding/dehydriding rate at a constant temperature. The alloys exhibit a different hydriding behavior when temperature was increased from 473K to 673K. The alloys particles became finer after long time milling, which led to a decrease in the different distance of the hydrogen atoms.

  8. Hydroamination reactions of alkynes with ortho-substituted anilines in ball mills: synthesis of benzannulated N-heterocycles by a cascade reaction.

    PubMed

    Weiße, Maik; Zille, Markus; Jacob, Katharina; Schmidt, Robert; Stolle, Achim

    2015-04-20

    It was demonstrated that ortho-substituted anilines are prone to undergo hydroamination reactions with diethyl acetylenedicarboxylate in a planetary ball mill. A sequential coupling of the intermolecular hydroamination reaction with intramolecular ring closure was utilized for the syntheses of benzooxazines, quinoxalines, and benzothiazines from readily available building blocks, that is, electrophilic alkynes and anilines with OH, NH, or SH groups in the ortho position. For the heterocycle formation, it was shown that several stress conditions were able to initiate the reaction in the solid state. Processing in a ball mill seemed to be advantageous over comminution with mortar and pestle with respect to process control. In the latter case, significant postreaction modification occurred during solid-state analysis. Cryogenic milling proved to have an adverse effect on the molecular transformation of the reagents. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Agile Thermal Management STT-RX. Catalytic Influence of Ni-based Additives on the Dehydrogentation Properties of Ball Milled MgH2 (PREPRINT)

    DTIC Science & Technology

    2011-12-01

    whereas the clamp speed is 1060 cycles per minute. The hydrides were milled in a 65-cm3 stainless steel vial using 15 stainless steel grinding balls ... balls in the high-energy vibratory mill combines strong shearing and impact forces in various proportions to increase the free energy of the system by...the dehydrogentation properties of ball milled MgH2 (PREPRINT) 5a. CONTRACT NUMBER In-house 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 62102F

  10. Stainless-Steel Ball-Milling Method for Hydro-/Deutero-genation using H2O/D2O as a Hydrogen/Deuterium Source.

    PubMed

    Sawama, Yoshinari; Kawajiri, Takahiro; Niikawa, Miki; Goto, Ryota; Yabe, Yuki; Takahashi, Tohru; Marumoto, Takahisa; Itoh, Miki; Kimura, Yuuichi; Monguchi, Yasunari; Kondo, Shin-ichi; Sajiki, Hironao

    2015-11-01

    A one-pot continuous-flow method for hydrogen (deuterium) generation and subsequent hydrogenation (deuterogenation) was developed using a stainless-steel (SUS304)-mediated ball-milling approach. SUS304, especially zero-valent Cr and Ni as constituents of the SUS304, and mechanochemical processing played crucial roles in the development of the reactions. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Development of cube textured Ni W alloy tapes using powder metallurgy along with high energy ball milling for HTS coated conductors

    NASA Astrophysics Data System (ADS)

    Zhou, Y. X.; Naguib, R.; Fang, H.; Salama, K.

    2004-07-01

    Ni based alloys have received considerable attention as the substrates for HTS coated conductors due to improved mechanical properties and reduced magnetization. Powder metallurgy is one of the promising processes for the fabrication of long alloy textured substrates. In this paper, Ni-3 at.% W alloy substrates were prepared by using high purity metal powders as starting materials. The Ni and 3 at.% W powder mixture was high energy ball milled for different periods, isostatically pressed, sintered, rolled and texture annealed. The high energy ball milling process made the powders mix uniformly and the grain sizes decrease significantly, which led to higher boundary energy and residual strain energy. The longer ball milling period resulted in a finer grain size and sharper texture in the substrate, which were confirmed by EBSD and SEM analysis. SEM and AFM observations indicate the surface of textured Ni-3 at.% W substrates is smooth and the roughness value (Rrms) is about 1.126 nm, which is suitable for deposition of buffer layers.

  12. Micromorphological changes and mechanism associated with wet ball milling of Pinus radiata substrate and consequences for saccharification at low enzyme loading.

    PubMed

    Vaidya, Alankar A; Donaldson, Lloyd A; Newman, Roger H; Suckling, Ian D; Campion, Sylke H; Lloyd, John A; Murton, Karl D

    2016-08-01

    In this work, substrates prepared from thermo-mechanical treatment of Pinus radiata chips were vibratory ball milled for different times. In subsequent enzymatic hydrolysis, percent glucan conversion passed through a maximum value at a milling time of around 120min and then declined. Scanning electron microscopy revealed breakage of fibers to porous fragments in which lamellae and fibrils were exposed during ball milling. Over-milling caused compression of the porous fragments to compact globular particles with a granular texture, decreasing accessibility to enzymes. Carbon-13 NMR spectroscopy showed partial loss of interior cellulose in crystallites, leveling off once fiber breakage was complete. A mathematical model based on observed micromorphological changes supports ball milling mechanism. At a low enzyme loading of 2FPU/g of substrate and milling time of 120min gave a total monomeric sugar yield of 306g/kg of pulp which is higher than conventional pretreatment method such as steam exploded wood. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. Preparation and characterization of nanocrystalline ZrO2-7%Y2O3 powders for thermal barrier coatings by high-energy ball milling

    NASA Astrophysics Data System (ADS)

    Bobzin, Kirsten; Zhao, Lidong; Schlaefer, Thomas; Warda, Thomas

    2011-06-01

    High-energy ball milling is an effective method to produce nanocrystalline oxides. In this study, a conventional ZrO2-7%Y2O3 spray powder was ball-milled to produce nanocrystalline powders with high levels of crystalline disorders for deposition of thermal barrier coatings. The powder was milled both with 100Cr6 steel balls and with ZrO2-3%Y2O3 ceramic balls as grinding media. The milling time was varied in order to investigate the effect of the milling time on the crystallite size. The powders were investigated in terms of their crystallite sizes and morphologies by X-ray diffraction analysis (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results show that under given milling conditions the powder was already nanostructured after 40 min milling. The crystallite size decreased significantly with increasing milling time within first 120 min. After that, a further increase of milling time did not lead to a significant reduction of the crystallite size. Ball-milling led to lattice microstrains. Milling with the steel balls resulted in finer nano-sized crystal grains, but caused the contamination of the powder. The nano-sized crystal grains coarsened during the heat-treatment at 1250°C.

  14. Preparation of an additive-free sample with a MgH2 phase by planetary ball milling of Mg with10 wt% MgH2

    NASA Astrophysics Data System (ADS)

    Hong, Seong-Hyeon; Song, Myoung Youp

    2016-11-01

    In order to prepare an additive-free sample with a MgH2 phase, 90 wt% Mg+10 wt% MgH2 (named Mg-10MgH2) was milled under hydrogen atmosphere in a planetary ball mill for different durations (2 h, 5 h, and 10 h). The hydrogen absorption and release properties of the prepared samples were investigated and compared with those of purchased pure MgH2 samples. Mg-10MgH2 milled for 5 h had the largest quantity of hydrogen released at 648 K for 100 min of 5.96 wt%. Mg-10MgH2 milled for 5 h released 0.11 wt% H for 10 min, 4.85 wt% H for 30 min, and 5.83 wt% H for 60 min at 648 K at the first cycle. Mg-10MgH2 milled for 5 h absorbed 5.39 wt% H for 5 min and 5.92 wt% H for 60 min at 648 K at the second cycle. Dehydriding curves were also obtained at the first cycle of Mg-10MgH2 samples milled for 5 h using Mg powder with or without sieving (200 mesh). The dehydriding curve at 648 K of a Mg-10MgH2 sample milled for 5 h in the planetary ball mill was compared with that of the sample milled for 24 h in a horizontal ball mill.

  15. Solid-state synthesis of Mg{sub 2}Si via short-duration ball-milling and low-temperature annealing

    SciTech Connect

    Ioannou, M.; Chrissafis, K.; Pavlidou, E.; Gascoin, F.; Kyratsi, Th.

    2013-01-15

    In this work, a short duration ball-milling of elemental Mg and Si followed by a thermal treatment is suggested in order to synthesize magnesium silicide via solid-state reaction. The formation of magnesium silicide was studied in terms of its structure and thermal characteristics by powder X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy and differential scanning calorimetry. Pure Mg{sub 2}Si was formed after short milling and heating at temperatures as low as 280 Degree-Sign C. Differential scanning calorimetry analysis was performed to study the kinetics of the reaction. The activation energy of the reaction was calculated using the Ozawa-Flynn-Wall and Friedman methods. The thermoelectric properties suggested semiconducting behavior whereas thermal conductivity values of highly dense hot-pressed pellets are consistent with the literature. - Graphical abstract: Thermographs of ball-milled Mg and Si powders (1 and 2) show exothermic areas suggesting Mg{sub 2}Si formation at low temperatures. Unmilled Mg and Si mixture (3) forms Mg{sub 2}Si at higher temperatures. Highlights: Black-Right-Pointing-Pointer Ball-milling process is crucial for the formation of pure Mg{sub 2}Si at low temperatures. Black-Right-Pointing-Pointer Synthesis profiles based on different temperature settings and duration are suggested. Black-Right-Pointing-Pointer Thermal analysis confirms the shift of the Mg{sub 2}Si formation at low temperatures.

  16. Synthesis of Nd2Fe14C compound by high-energy ball-milling Nd-Fe alloy in heptane and annealing under vacuum

    NASA Astrophysics Data System (ADS)

    Geng, H. M.; Ji, Y.; Feng, X. Y.; Zhang, J. J.; Ran, Z.; Yan, Y.; Wang, W. Q.; Su, F.; Du, X. B.

    2016-06-01

    A simple synthesis route for the Nd2Fe14C compound with good permanent magnetic properties is presented. Being high-energy ball-milled in heptane (C7H16) for 8 h, the NdFe3.5 alloy consisting of Nd2Fe17 and Nd phases disproportionates into NdH2+δ and α-Fe. Subsequently, NdH2+δ decomposes when annealed from room temperature to 900 °C under vacuum, and H2 is released. Meanwhile Nd2Fe14C, NdC and little α-Fe phases are formed in the final product. H and C atoms come from the decomposition of heptane. Coercivity of 1.39 T and maximum magnetic energy product of 62.7 kJ m-3 have been achieved. Too short a ball-milling time results in the insufficient disproportionation of NdFe3.5 alloy and the residue of Nd2Fe17 phase in the final product. Too long a ball-milling time results in the appearance of NdC2 and more α-Fe phases besides Nd2Fe14C and NdC phases. Hexane (C6H14), octane (C8H18) and nonane (C9H20) have been proved to have a similar effect to heptane.

  17. Synthesis, characterization and performance of high energy ball milled meso-scale zero valent iron in Fenton reaction.

    PubMed

    Ambika, Selvaraj; Devasena, M; Nambi, Indumathi Manivannan

    2016-10-01

    Understanding contaminant degradation by different sized zero valent iron (ZVI) particles is one important aspect in addressing the long-term stability of these particles in field studies. In this study, meso zero valent iron (mZVI) particles were synthesised in a milling time of 10 h using ball milling technique. The efficacy of mZVI particles for removal of phenol was quantitatively evaluated in comparison with coarse zero valent iron (cZVI) and nano zero valent iron (nZVI) particles. Phenol degradation experiments were carried out in sacrificial batch mode at room temperature independently with cZVI, nZVI and mZVI under varied pH conditions of 3, 4, 6, 7, 8 and 10. Batch experiments substantiating the reactivity of mZVI under unbuffered pH system were also carried out and compared with buffered and poorly buffered pH systems. mZVI particles showed consistent phenol degradation at circum-neutral pH with efficiency of 44%, 67%, and 89% in a span of 5, 10 and 20 min respectively. The dissolved iron species and residual iron formation were also measured as a function of pH. Unbuffered systems at circum-neutral pH produced less residual iron when compared to buffered and poorly buffered systems. At this pH, oxidation of Fe(2+) produced a different oxidant Ferryl ion, which was found to effectively participate in phenol degradation.

  18. Preparation of TiO₂-Decorated Boron Particles by Wet Ball Milling and their Photoelectrochemical Hydrogen and Oxygen Evolution Reactions.

    PubMed

    Jung, Hye Jin; Nam, Kyusuk; Sung, Hong-Gye; Hyun, Hyung Soo; Sohn, Youngku; Shin, Weon Gyu

    2016-12-14

    TiO₂-coated boron particles were prepared by a wet ball milling method, with the particle size distribution and average particle size being easily controlled by varying the milling operation time. Based on the results from X-ray photoelectron spectroscopy, transmission electron microscopy, energy dispersive X-ray analysis, and Fourier transform infrared spectroscopy, it was confirmed that the initial oxide layer on the boron particles surface was removed by the wet milling process, and that a new B-O-Ti bond was formed on the boron surface. The uniform TiO₂ layer on the 150 nm boron particles was estimated to be 10 nm thick. Based on linear sweep voltammetry, cyclic voltammetry, current-time amperometry, and electrochemical impedance analyses, the potential for the application of TiO₂-coated boron particles as a photoelectrochemical catalyst was demonstrated. A current of 250 μA was obtained at a potential of 0.5 V for hydrogen evolution, with an onset potential near to 0.0 V. Finally, a current of 220 μA was obtained at a potential of 1.0 V for oxygen evolution.

  19. Preparation of Mg-MgH2 flakes by planetary ball milling with stearic acid and their hydrogen storage properties

    NASA Astrophysics Data System (ADS)

    Hong, Seong-Hyeon; Song, Myoung Youp

    2016-05-01

    Many studies preparing magnesium hydride using catalyst addition were performed, resulting in the preparation of additive-containing magnesium hydride. Preparation of a sample with a MgH2 phase without additives requires high pressure and high temperature and is time-demanding. In order to prepare an additive-free sample with a MgH2 phase, 90 wt% Mg+10 wt% MgH2 (named 90Mg+10MgH2) was milled under a hydrogen atmosphere with 6 wt% stearic acid as a process-controlling agent, which led to a formation of Mg-MgH2 flakes. The hydrogen storing and releasing properties of the prepared flakes were investigated and compared with those of purchased MgH2. A sample with a majority fraction of MgH2 phase was prepared by planetary ball milling of 90 Mg+10 MgH2 with 6 wt% stearic acid. The resultant particles of 90 Mg+10 MgH2 obtained after hydridingdehydriding cycling were much smaller and had significantly more cracks and defects than those of MgH2 after hydriding-dehydriding cycling. 90 Mg+10 MgH2 released 0.12 wt% hydrogen for 4 min, 3.70 wt% for 20 min, and 5.30 wt% for 60 min at 648 K at the first cycle.

  20. Pretreatment of eucalyptus wood chips for enzymatic saccharification using combined sulfuric acid-free ethanol cooking and ball milling.

    PubMed

    Teramoto, Yoshikuni; Tanaka, Noriko; Lee, Seung-Hwan; Endo, Takashi

    2008-01-01

    A combined sulfuric acid-free ethanol cooking and pulverization process was developed in order to achieve the complete saccharification of the cellulosic component of woody biomass, thereby avoiding the problems associated with the use of strong acid catalysts. Eucalyptus wood chips were used as a raw material and exposed to an ethanol/water/acetic acid mixed solvent in an autoclave. This process can cause the fibrillation of wood chips. During the process, the production of furfural due to an excessive degradation of polysaccharide components was extremely low and delignification was insignificant. Therefore, the cooking process is regarded not as a delignification but as an activation of the original wood. Subsequently, the activated solid products were pulverized by ball-milling in order to improve their enzymatic digestibility. Enzymatic hydrolysis experiments demonstrated that the conversion of the cellulosic components into glucose attained 100% under optimal conditions. Wide-angle X-ray diffractometry and particle size distribution analysis revealed that the scale affecting the improvement of enzymatic digestibility ranged from 10 nm to 1 microm. Field emission scanning electron microscopy depicted that the sulfuric acid-free ethanol cooking induced a pore formation by the removal of part of the lignin and hemicellulose fractions in the size range from a few of tens nanometers to several hundred nanometers.

  1. Removal of fluoride from drinking water using modified ultrafine tea powder processed using a ball-mill

    NASA Astrophysics Data System (ADS)

    Cai, Huimei; Xu, Lingyun; Chen, Guijie; Peng, Chuanyi; Ke, Fei; Liu, Zhengquan; Li, Daxiang; Zhang, Zhengzhu; Wan, Xiaochun

    2016-07-01

    A low-cost and highly efficient biosorbent was prepared by loading zirconium(IV) onto ball-milled, ultrafine tea powder (UTP-Zr) for removal of fluoride from drinking water. To evaluate the fluoride adsorption capacity of UTP-Zr over a wide range of conditions, the biosorbent dosage, contact time, initial pH, initial fluoride concentration and presence of other ions were varied. UTP-Zr performed well over the considerably wide pH range of 3-10. The residual concentration of Zr in the treated water was below the limit of detection (0.01 mg/L). Fluoride adsorption by the UTP-Zr biosorbent followed the Langmuir model, with a maximum adsorption capacity of 12.43 mgF/g at room temperature. The fluoride adsorption kinetics fit the pseudo-second-order kinetic model. The synthesized biosorbent was characterized by BET, SEM, EDS, XRD and XPS to reveal how UTP-Zr interacts with fluoride. Results from this study demonstrated that UTP-based biosorbents will be useful and safe for the removal of fluoride from drinking water.

  2. High-Efficient Production of Boron Nitride Nanosheets via an Optimized Ball Milling Process for Lubrication in Oil

    PubMed Central

    Deepika, D; Li, Lu Hua; Glushenkov, Alexey M.; Hait, Samik K.; Hodgson, Peter; Chen, Ying

    2014-01-01

    Although tailored wet ball milling can be an efficient method to produce a large quantity of two-dimensional nanomaterials, such as boron nitride (BN) nanosheets, milling parameters including milling speed, ball-to-powder ratio, milling ball size and milling agent, are important for optimization of exfoliation efficiency and production yield. In this report, we systematically investigate the effects of different milling parameters on the production of BN nanosheets with benzyl benzoate being used as the milling agent. It is found that small balls of 0.1–0.2 mm in diameter are much more effective in exfoliating BN particles to BN nanosheets. Under the optimum condition, the production yield can be as high as 13.8% and the BN nanosheets are 0.5–1.5 μm in diameter and a few nanometers thick and of relative high crystallinity and chemical purity. The lubrication properties of the BN nanosheets in base oil have also been studied. The tribological tests show that the BN nanosheets can greatly reduce the friction coefficient and wear scar diameter of the base oil. PMID:25470295

  3. High-efficient production of boron nitride nanosheets via an optimized ball milling process for lubrication in oil.

    PubMed

    Deepika; Li, Lu Hua; Glushenkov, Alexey M; Hait, Samik K; Hodgson, Peter; Chen, Ying

    2014-12-03

    Although tailored wet ball milling can be an efficient method to produce a large quantity of two-dimensional nanomaterials, such as boron nitride (BN) nanosheets, milling parameters including milling speed, ball-to-powder ratio, milling ball size and milling agent, are important for optimization of exfoliation efficiency and production yield. In this report, we systematically investigate the effects of different milling parameters on the production of BN nanosheets with benzyl benzoate being used as the milling agent. It is found that small balls of 0.1-0.2 mm in diameter are much more effective in exfoliating BN particles to BN nanosheets. Under the optimum condition, the production yield can be as high as 13.8% and the BN nanosheets are 0.5-1.5 μm in diameter and a few nanometers thick and of relative high crystallinity and chemical purity. The lubrication properties of the BN nanosheets in base oil have also been studied. The tribological tests show that the BN nanosheets can greatly reduce the friction coefficient and wear scar diameter of the base oil.

  4. High-Efficient Production of Boron Nitride Nanosheets via an Optimized Ball Milling Process for Lubrication in Oil

    NASA Astrophysics Data System (ADS)

    Deepika; Li, Lu Hua; Glushenkov, Alexey M.; Hait, Samik K.; Hodgson, Peter; Chen, Ying

    2014-12-01

    Although tailored wet ball milling can be an efficient method to produce a large quantity of two-dimensional nanomaterials, such as boron nitride (BN) nanosheets, milling parameters including milling speed, ball-to-powder ratio, milling ball size and milling agent, are important for optimization of exfoliation efficiency and production yield. In this report, we systematically investigate the effects of different milling parameters on the production of BN nanosheets with benzyl benzoate being used as the milling agent. It is found that small balls of 0.1-0.2 mm in diameter are much more effective in exfoliating BN particles to BN nanosheets. Under the optimum condition, the production yield can be as high as 13.8% and the BN nanosheets are 0.5-1.5 μm in diameter and a few nanometers thick and of relative high crystallinity and chemical purity. The lubrication properties of the BN nanosheets in base oil have also been studied. The tribological tests show that the BN nanosheets can greatly reduce the friction coefficient and wear scar diameter of the base oil.

  5. Textured PrCo{sub 5} nanoflakes with large coercivity prepared by low power surfactant-assisted ball milling

    SciTech Connect

    Zuo, Wen-Liang Liu, Rong-Ming; Zheng, Xin-Qi; Wu, Rong-Rong; Hu, Feng-Xia; Sun, Ji-Rong; Shen, Bao-Gen

    2014-05-07

    The effect of the milling time on the structure, morphology, coercivity, and remanence ratio of textured PrCo{sub 5} nanoflakes produced by low power surfactant-assisted ball milling (SABM) was investigated. The X-ray powder diffraction (XRD) patterns indicate that the SABM PrCo{sub 5} samples are all CaCu{sub 5}-type hexagonal structure. The average grain size is smaller than 10 nm when the SABM time is equal to or longer than 5.5 h. The thickness of nanoflakes is mainly in the range of 50−100 nm while the length is 0.5−5 μm when the SABM time reaches 8 h. For the field-aligned PrCo{sub 5} nanoflakes, the out-of-plane texture is indicated from the increasing (0 0 l) peaks in the XRD patterns, and the easy magnetization direction is perpendicular to the flake surface. The strong texture of PrCo{sub 5} nanoflakes leads to a large coercivity H{sub c} (7.8 kOe) and obvious anisotropic magnetic behaviors for the aligned samples.

  6. Spark plasma sintered Sm(2)Co(17)-FeCo nanocomposite permanent magnets synthesized by high energy ball milling.

    PubMed

    Sreenivasulu, G; Gopalan, R; Chandrasekaran, V; Markandeyulu, G; Suresh, K G; Murty, B S

    2008-08-20

    Nanocomposite Sm(2)Co(17)-5 wt% FeCo magnets were synthesized by high energy ball milling followed by consolidation into bulk shape by the spark plasma sintering technique. The evolution of magnetic properties was systematically investigated in milled powders as well as in spark plasma sintered samples. A high energy product of 10.2 MGOe and the other magnetic properties of M(s) = 107 emu g(-1), M(r) = 59 emu g(-1), M(r)/M(s) = 0.55 and H(c) = 6.4 kOe were achieved in a 5 h milled and spark plasma sintered Sm(2)Co(17)-5 wt% FeCo nanocomposite magnet. The spark plasma sintering was carried out at 700 °C for 5 min with a pressure of 70 MPa. The nanocomposite showed a higher Curie temperature of 955 °C for the Sm(2)Co(17) phase in comparison to its bulk Curie temperature for the Sm(2)Co(17) phase (920 °C). This higher Curie temperature can improve the performance of the magnet at higher temperatures.

  7. Nanocrystalline Nd2Fe17 synthesized by high-energy ball milling: crystal structure, microstructure and magnetic properties.

    PubMed

    Álvarez, Pablo; Gorria, Pedro; Franco, Victorino; Sánchez Marcos, Jorge; Pérez, María J; Sánchez Llamazares, José L; Puente Orench, Inés; Blanco, Jesús A

    2010-06-02

    Nanocrystalline Nd(2)Fe(17) powders have been obtained by means of high-energy ball milling from nearly single-phase bulk alloys produced by arc melting and high temperature homogenization annealing. The rhombohedral Th(2)Zn(17)-type crystal structure of the bulk alloy remains unaltered after the milling process, with almost unchanged values for the cell parameters. However, the severe mechanical processing induces drastic microstructural changes. A decrease of the mean crystalline size down to around 10 nm is observed, giving rise to a considerable augmentation of the disordered inter-grain boundaries. This modification of the microstructure affects the magnetic behaviour of the milled powders, although the magnetic structure remains collinear ferromagnetic. While a unique ferro-to-paramagnetic transition temperature, T(C) = 339 ± 2 K, is observed in the bulk alloy, the nanocrystalline samples exhibit a more likely distribution of T(C) values. The latter seems to be responsible for the significant broadening of the temperature range in which magneto-caloric effect is observed, and the lowering of the maximum value of the magnetic entropy change.

  8. DEM modeling of ball mills with experimental validation: influence of contact parameters on charge motion and power draw

    NASA Astrophysics Data System (ADS)

    Boemer, Dominik; Ponthot, Jean-Philippe

    2017-01-01

    Discrete element method simulations of a 1:5-scale laboratory ball mill are presented in this paper to study the influence of the contact parameters on the charge motion and the power draw. The position density limit is introduced as an efficient mathematical tool to describe and to compare the macroscopic charge motion in different scenarios, i.a. with different values of the contact parameters. While the charge motion and the power draw are relatively insensitive to the stiffness and the damping coefficient of the linear spring-slider-damper contact law, the coefficient of friction has a strong influence since it controls the sliding propensity of the charge. Based on the experimental calibration and validation by charge motion photographs and power draw measurements, the descriptive and predictive capabilities of the position density limit and the discrete element method are demonstrated, i.e. the real position of the charge is precisely delimited by the respective position density limit and the power draw can be predicted with an accuracy of about 5 %.

  9. Quenching ilmenite with a high-temperature and high-pressure phase using super-high-energy ball milling

    PubMed Central

    Hashishin, Takeshi; Tan, Zhenquan; Yamamoto, Kazuhiro; Qiu, Nan; Kim, Jungeum; Numako, Chiya; Naka, Takashi; Valmalette, Jean Christophe; Ohara, Satoshi

    2014-01-01

    The mass production of highly dense oxides with high-temperature and high-pressure phases allows us to discover functional properties that have never been developed. To date, the quenching of highly dense materials at the gramme-level at ambient atmosphere has never been achieved. Here, we provide evidence of the formation of orthorhombic Fe2TiO4 from trigonal FeTiO3 as a result of the high-temperature (>1250 K) and high-pressure (>23 GPa) condition induced by the high collision energy of 150 gravity generated between steel balls. Ilmenite was steeply quenched by the surrounding atmosphere, when iron-rich ilmenite (Fe2TiO4) with a high-temperature and high-pressure phase was formed by planetary collisions and was released from the collision points between the balls. Our finding allows us to infer that such intense planetary collisions induced by high-energy ball milling contribute to the mass production of a high-temperature and high-pressure phase. PMID:24763088

  10. Preparation of CNT/AlSi10Mg composite powders by high-energy ball milling and their physical properties

    NASA Astrophysics Data System (ADS)

    Wang, Lin-zhi; Liu, Ying; Wei, Wen-hou; An, Xu-guang; Zhang, Tao; Pu, Ya-yun

    2016-03-01

    This study investigated the effects of carbon nanotube (CNT) concentration on the micro-morphologies and laser absorption properties of CNT/AlSi10Mg composite powders produced by high-energy ball milling. A scanning electron microscope, X-ray diffractometer, laser particle size analyzer, high-temperature synchronous thermal analyzer, and UV/VIS/NIR spectrophotometer were used for the analysis of micrographs, phases, granulometric parameters, thermal properties, and laser absorption properties of the composite powders, respectively. The results showed that the powders gradually changed from flake- to granule-like morphology and the average particle size sharply decreased with increases in milling rotational speed and milling time. Moreover, a uniform dispersion of CNTs in AlSi10Mg powders was achieved only for a CNT content of 1.5wt%. Laser absorption values of the composite powders were also observed to gradually increase with the increase of CNT concentration, and different spectra displayed characteristic absorption peaks at a wavelength of approximately 826 nm.

  11. Quenching ilmenite with a high-temperature and high-pressure phase using super-high-energy ball milling.

    PubMed

    Hashishin, Takeshi; Tan, Zhenquan; Yamamoto, Kazuhiro; Qiu, Nan; Kim, Jungeum; Numako, Chiya; Naka, Takashi; Valmalette, Jean Christophe; Ohara, Satoshi

    2014-04-25

    The mass production of highly dense oxides with high-temperature and high-pressure phases allows us to discover functional properties that have never been developed. To date, the quenching of highly dense materials at the gramme-level at ambient atmosphere has never been achieved. Here, we provide evidence of the formation of orthorhombic Fe2TiO4 from trigonal FeTiO3 as a result of the high-temperature (>1250 K) and high-pressure (>23 GPa) condition induced by the high collision energy of 150 gravity generated between steel balls. Ilmenite was steeply quenched by the surrounding atmosphere, when iron-rich ilmenite (Fe2TiO4) with a high-temperature and high-pressure phase was formed by planetary collisions and was released from the collision points between the balls. Our finding allows us to infer that such intense planetary collisions induced by high-energy ball milling contribute to the mass production of a high-temperature and high-pressure phase.

  12. Grinding Wear Behaviour of Stepped Austempered Ductile Iron as Media Material During Comminution of Iron Ore in Ball Mills

    SciTech Connect

    Raghavendra, H.; Bhat, K. L.; Udupa, K. Rajendra; Hegde, M. M. Rajath

    2011-01-17

    An attempt has been made to evaluate the suitability of austempered ductile iron (ADI) as media material for grinding iron ore in a ball mill. Spheroidal graphite (S.G) iron balls are austenitised at 900 deg. C for 60 minutes and given stepped austempering treatment at 280 deg. C for 30 minutes and 60 minutes followed by 380 deg. C for 60 minutes in each case. These materials are characterised by measuring hardness, analysing X-ray diffraction (X-RD), studying microstructure using optical and scanning electron microscope (SEM). Grinding wear behaviour of these materials was assessed for wear loss in wet condition at different pH value of the mineral slurry and found that the wear rate of grinding media material decreases with increase in pH of the slurry. The wear resistance of ADI balls were compared with forged En31 steel balls and found that the stepped austempered ductile iron is superior to forged En31 steel balls.

  13. Quantification of residual crystallinity in ball milled commercially sourced lactose monohydrate by thermo-analytical techniques and terahertz spectroscopy.

    PubMed

    Smith, Geoff; Hussain, Amjad; Bukhari, Nadeem Irfan; Ermolina, Irina

    2015-05-01

    The quantification of crystallinity is necessary in order to be able to control the milling process. The use of thermal analysis for this assessment presents certain challenges, particularly in the case of crystal hydrates. In this study, the residual crystallinity on ball milling of lactose monohydrate (LMH), for periods up to 90min, was evaluated by thermo-analytical techniques (TGA, DSC) and terahertz spectroscopy (THz). In general, the results from one of the DSC analysis and the THz measurements agree showing a monotonous decrease in relative residual crystallinity with milling time (∼80% reduction after 60min milling) and a slight increase at the 90min time point. However, the estimates from TGA and two other methods of analyzing DSC curve do not agree with the former techniques and show variability with significantly higher estimates for crystallinity. It was concluded that, the thermal techniques require more complex treatment of the data in the evaluation of changes in crystallinity of a milled material (in particular to account for the de-vitrification and mutarotation of the material that inevitably occurs during the measurement cycle) while the analysis of THz data is more straightforward, with the measurement having no impact on the native state of the material. Copyright © 2015 Elsevier B.V. All rights reserved.

  14. Two step meso-acidophilic bioleaching of chalcopyrite containing ball mill spillage and removal of the surface passivation layer.

    PubMed

    Panda, S; Parhi, P K; Nayak, B D; Pradhan, N; Mohapatra, U B; Sukla, L B

    2013-02-01

    Meso-acidophilic bacterial leaching of ball mill spillage (containing chalcopyrite >80%) was carried out in an innovative two-step bioleaching method. The major drawback of meso-acidophilic bioleaching limiting industrial application is the passivation phenomenon over the ore surfaces in iron-sulfur rich environments. In the present study, we present a novel wash solution that efficiently removed the passivation layer. FTIR characterization of the bioleached sample indicated that the residues could be further leached to recover extra copper after wash solution application. XRD study indicated accumulation of sulfates (SO(4)(-)) of Na, K, Fe and oxy hydroxides of iron [FeO(OH)] in the form of jarosite outlining the passivation layer. SEM, FESEM-EDS studies indicated severe corrosion effects of the wash solution on the passivation layer. Two step bioleaching of the ore sample yielded 32.6% copper in 68days in the first interlude and post wash solution application yielded 10.8% additional copper. Copyright © 2012 Elsevier Ltd. All rights reserved.

  15. A novel combined pretreatment of ball milling and microwave irradiation for enhancing enzymatic hydrolysis of microcrystalline cellulose.

    PubMed

    Peng, Huadong; Li, Hongqiang; Luo, Hao; Xu, Jian

    2013-02-01

    Microcrystalline cellulose (MCC) was performed as a mode substrate to investigate its potential ability of bioconversion in a novel combined pretreatment of ball milling (BM) and/or microwave irradiation (MWI). The variation of structure characteristics of MCC before/after pretreatment were investigated, including crystallinity index (CrI), size of crystal (S(C)), specific surface area (SSA) and degree of polymerization (DP). Their correlation with the rate of enzymatic hydrolysis was differentiated by an optimized equation which indicated the rate of hydrolysis was much more sensitive to CrI than SSA and DP. To achieve the same or higher glucose yield of BM for 3h and 6h, BM for 1h with MWI for 20min could save 54.8% and 77.40% energy consumption, respectively. Moreover, chemicals were not required in this process. It is concluded that the combination of BM and short time MWI is an environment-friendly, economical and effective approach to treat biomass.

  16. Hydroformylation of Alkenes in a Planetary Ball Mill: From Additive-Controlled Reactivity to Supramolecular Control of Regioselectivity.

    PubMed

    Cousin, Kévin; Menuel, Stéphane; Monflier, Eric; Hapiot, Frédéric

    2017-08-21

    The Rh-catalyzed hydroformylation of aromatic-substituted alkenes is performed in a planetary ball mill under CO/H2 pressure. The dispersion of the substrate molecules and the Rh-catalyst into the grinding jar is ensured by saccharides: methyl-α-d-glucopyranoside, acyclic dextrins, or cyclodextrins (CDs, cyclic oligosaccharides). The reaction affords the exclusive formation of aldehydes whatever the saccharide. Acyclic saccharides disperse the components within the solid mixture leading to high conversions of alkenes. However, they showed typical selectivity for α-aldehyde products. If CDs are the dispersing additive, the steric hindrance exerted by the CDs on the primary coordination sphere of the metal modifies the selectivity so that the β-aldehydes were also formed in non-negligible proportions. Such through-space control via hydrophobic effects over reactivity and regioselectivity reveals the potential of such solventless process for catalysis in solid state. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Mechanochemical degradation of γ-hexachlorocyclohexane by a planetary ball mill in the presence of CaO.

    PubMed

    Nomura, Yugo; Fujiwara, Kazuo; Terada, Akihiko; Nakai, Satoshi; Hosomi, Masaaki

    2012-01-01

    Although the use of the insecticide γ-hexachlorocyclohexane (HCH) is now prohibited in many countries because of its hazardousness, stockpiles of γ-HCH still exist. In this study, we subjected γ-HCH to mechanochemical (MC) treatment with a planetary ball mill in the presence of CaO to investigate the feasibility of using this method for the treatment of γ-HCH stockpiles. We confirmed the degradation of γ-HCH and investigated the degradation mechanism. The major intermediates were identified to be 1,3,4,5,6-pentachlorocyclohexene (γ-PCCH) and chlorobenzenes (CBzs). Analysis of the steric structure of γ-HCH and identification of the degradation intermediates suggested that successive dehydrochlorination led to the formation of trichlorobenzenes. Products of further degradation (dichlorobenzenes, monochlorobenzene, and benzene) were also detected. Surprisingly, methane and ethane were also detected, which suggests cleavage of the C-C bonds of the cyclohexane ring and hydrogenation. All of the chlorine atoms in the γ-HCH could be transformed into inorganic chloride compounds by the MC treatment with CaO. Our results indicate that γ-HCH can be completely dechlorinated by MC treatment. Copyright © 2011 Elsevier Ltd. All rights reserved.

  18. The phase analysis of spark plasma sintered MgB2 after ball milling.

    PubMed

    Kang, Deuk-Kyun; Kim, Dong-Woong; Kim, Cheol-Jin; Ahn, In-Shup

    2010-01-01

    Mg and amorphous B powders below 10 and 3 micro meter were used as raw materials, and mixed by planetary-mill for 9 hours at argon atmosphere. MgB2 bulk was fabricated at the various temperatures by Spark Plasma Sintering. In the sintering process, mixed powders were sintered in graphite mold, at the pressure of 55 Mpa. The fabricated MgB2 samples were evaluated with XRD, EDS, FE-SEM, PPMS. MgB2, MgO and Fe phases were observed from XRD result. In the results, MgO and Fe were impurity which may affect superconducting properties of MgB2 samples, and it's distribution could be confirmed from EDS mapping result. In order to confirm the formation of MgB2 phase, DTA was used as heating rate of 10 degrees C/min at Ar atmosphere from room temperature to 1200 degrees C. In the PPMS result, the Tc (critical temperature) was about 21 K, and the density of spark plasma sintered samples increased to 1.87 g/cm3 by increasing sintering temperature.

  19. Combustion synthesis of amorphous boron in a very-short-term magnesiothermic reduction

    NASA Astrophysics Data System (ADS)

    Semnan, Masih; Jalaly, Maisam

    2016-11-01

    Nanosized amorphous boron powder was produced using mechanochemistry via a magnesiothermic reduction in a Mg/B2O3 system. High-energy ball milling was used to induce a mechanically induced self-sustaining reaction. Under severe milling conditions it was found that the ignition time for boron formation was only about 27 min of milling. In this study, the formation of boron and its amorphous nature is demonstrated by various characterizations.

  20. Mechanical ball-milling preparation of fullerene/cobalt core/shell nanocomposites with high electrochemical hydrogen storage ability.

    PubMed

    Bao, Di; Gao, Peng; Shen, Xiande; Chang, Cheng; Wang, Longqiang; Wang, Ying; Chen, Yujin; Zhou, Xiaoming; Sun, Shuchao; Li, Guobao; Yang, Piaoping

    2014-02-26

    The design and synthesis of new hydrogen storage nanomaterials with high capacity at low cost is extremely desirable but remains challenging for today's development of hydrogen economy. Because of the special honeycomb structures and excellent physical and chemical characters, fullerenes have been extensively considered as ideal materials for hydrogen storage materials. To take the most advantage of its distinctive symmetrical carbon cage structure, we have uniformly coated C60's surface with metal cobalt in nanoscale to form a core/shell structure through a simple ball-milling process in this work. The X-ray diffraction (XRD), scanning electron microscope (SEM), Raman spectra, high-solution transmission electron microscopy (HRTEM), energy-dispersive X-ray spectrometry (EDX) elemental mappings, and X-ray photoelectron spectroscopy (XPS) measurements have been conducted to evaluate the size and the composition of the composites. In addition, the blue shift of C60 pentagonal pinch mode demonstrates the formation of Co-C chemical bond, and which enhances the stability of the as-obtained nanocomposites. And their electrochemical experimental results demonstrate that the as-obtained C60/Co composites have excellent electrochemical hydrogen storage cycle reversibility and considerably high hydrogen storage capacities of 907 mAh/g (3.32 wt % hydrogen) under room temperature and ambient pressure, which is very close to the theoretical hydrogen storage capacities of individual metal Co (3.33 wt % hydrogen). Furthermore, their hydrogen storage processes and the mechanism have also been investigated, in which the quasi-reversible C60/Co↔C60/Co-Hx reaction is the dominant cycle process.

  1. Coercivity and superparamagnetic evolution of high energy ball milled (HEBM) bulk CoFe{sub 2}O{sub 4} material

    SciTech Connect

    Moyet, Richard Perez; Cardona, Yenny; Vargas, Pedro; Silva, Josue; Uwakweh, Oswald N.C.

    2010-12-15

    Ball milling (BM) of bulk CoFe{sub 2}O{sub 4} powder material carried out in order to study its structural stability and attendant property changes with respect to coercivity enhancements and superparamagnetic behaviors, showed that drastic crystallite size reduction occurred within the first 1 h of ball milling. Crystallite size dropped from 74 nm for the as-received material to a value of 11.6 nm for 600 min of ball milling. Combined X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses confirmed crystallite size reduction with corresponding increase in interparticle agglomeration/pores with increasing milling time. The maximum coercivity of 0.46 T and the crystallite size of 15.6 nm were recorded with 20 min, while peak residual strain of 0.0066 mm/mm was for 180 min of BM. Material with peak coercivity value did not have peak residual strain, or minimum crystallite size, thereby suggesting that other structural defects contributed to coercivity enhancement. The saturation magnetization (M{sub s}) value decreased continuously with increasing milling time, while remanence magnetization (M{sub r}) and coercivity decreased with increasing BM time, after an initial increase. Moessbauer spectroscopy (MS) measurements confirmed both particle size distribution and decomposition/disordering of the material together with superparamagnetism as BM time increased. The degree of inversion ranged from 41% to 71.7% at different milled states from Moessbauer spectroscopy. The internal magnetic fields of the Fe sites associated with the tetrahedral and octahedral sites were 507.4 kOe and 492 kOe respectively in the unmilled state, while 484 kOe and 468.5 kOe in the 600 min milled state correspondingly.

  2. Recycling process for recovery of gallium from GaN an e-waste of LED industry through ball milling, annealing and leaching.

    PubMed

    Swain, Basudev; Mishra, Chinmayee; Kang, Leeseung; Park, Kyung-Soo; Lee, Chan Gi; Hong, Hyun Seon

    2015-04-01

    Waste dust generated during manufacturing of LED contains significant amounts of gallium and indium, needs suitable treatment and can be an important resource for recovery. The LED industry waste dust contains primarily gallium as GaN. Leaching followed by purification technology is the green and clean technology. To develop treatment and recycling technology of these GaN bearing e-waste, leaching is the primary stage. In our current investigation possible process for treatment and quantitative leaching of gallium and indium from the GaN bearing e-waste or waste of LED industry dust has been developed. To recycle the waste and quantitative leaching of gallium, two different process flow sheets have been proposed. In one, process first the GaN of the waste the LED industry dust was leached at the optimum condition. Subsequently, the leach residue was mixed with Na2CO3, ball milled followed by annealing, again leached to recover gallium. In the second process, the waste LED industry dust was mixed with Na2CO3, after ball milling and annealing, followed acidic leaching. Without pretreatment, the gallium leaching was only 4.91 w/w % using 4M HCl, 100°C and pulp density of 20g/L. After mechano-chemical processing, both these processes achieved 73.68 w/w % of gallium leaching at their optimum condition. The developed process can treat and recycle any e-waste containing GaN through ball milling, annealing and leaching. Copyright © 2015 Elsevier Inc. All rights reserved.

  3. Band gap-engineered ZnO and Ag/ZnO by ball-milling method and their photocatalytic and Fenton-like photocatalytic activities

    NASA Astrophysics Data System (ADS)

    Choi, Young In; Jung, Hye Jin; Shin, Weon Gyu; Sohn, Youngku

    2015-11-01

    The hybridization of ZnO with Ag has been performed extensively to increase the efficiency of ZnO in various applications, including catalysis. In this study, a wet (w) and dry (d) ball-milling method was used to hybridize Ag with ZnO nanoparticles, and their physicochemical properties were examined. Visible light absorption was enhanced and the band gap was engineered by ball-milling and Ag hybridization. Their photocatalytic activities were tested with rhodamine B (RhB) and a mixed dye (methyl orange + RhB + methylene blue) under visible light irradiation. For pure RhB, the photocatalytic activity was decreased by ball-milling and was observed in the order of ZnO(d) < Ag/ZnO(d) < ZnO(w) < Ag/ZnO(w) ≤ ZnO(ref). For the degradation of RhB and methylene blue (MB) in the mixed dye (or the simulated real contaminated water), the photocatalytic activity was observed in the order of Ag/ZnO(d) < ZnO(d) < ZnO(w) < Ag/ZnO(w) ≤ ZnO(ref). When the photodegradation tested with H2O2 addition, however, the Fenton-like photocatalytic activity was reversed and the ZnO(ref) showed the poorest activity for the degradation of RhB and methylene blue (MB). In the mixed dye over all the catalysts, methyl orange (MO) was degraded most rapidly. The relative degradation rates of RhB and MB were found to be dependent on the catalyst and reaction conditions.

  4. Microstructural evolution of nanostructured Ti{sub 0.7}Ni{sub 0.3}N prepared by reactive ball-milling

    SciTech Connect

    Bhaskar, Ujjwal Kumar; Pradhan, S.K.

    2013-09-01

    Graphical abstract: - Highlights: • α-Ti to β-Ti phase conversion is observed during 1 h of milling. • Ti{sub 0.7}Ni{sub 0.3}N (fcc) phase is noticed to form after 1 h of milling. • Formation time of Ti(Ni,N) phase is same as TiN phase. • Both X-ray and HRTEM microstructure characterization revealed similar results. - Abstract: Nanocrystalline stoichiometric Ti{sub 0.7}Ni{sub 0.3}N powder has been synthesized by ball-milling the α-Ti (hcp) and Ni (fcc) powders under N{sub 2} gas at room temperature. The α-Ti phase partially transforms to the transient (-Ti phase after 1 h of milling. After 5.5 h of milling, very broad reflections of Ti{sub 0.7}Ni{sub 0.3}N phase is noticed. Complete formation of Ti{sub 0.7}Ni{sub 0.3}N phase is observed after 9 h of milling. Microstructure in terms of lattice imperfections of unmilled and all ball-milled powder mixtures are primarily characterized by analyzing the X-ray powder diffraction patterns employing the Rietveld structure refinement procedure. It clearly reveals the presence of Ti{sub 0.7}Ni{sub 0.3}N phase and inclusion of nitrogen atoms into the α-Ti–Ni matrix on the way to formation of nitride phase. Microstructure of the ball milled nitride powders is also characterized by HRTEM. Particle size of Ti{sub 0.7}Ni{sub 0.3}N phase obtained from XRD method of characterization is ∼5 nm which is very close to that obtained from HRTEM.

  5. Hyperfine and Magnetic Properties of Nanosized Ni0.5Zn0.5Fe2O4 Synthesized by High-energy Ball Milling

    NASA Astrophysics Data System (ADS)

    Mukherjee, S.; Dey, S.; Ghosh, B.; Kuamr, S.; Poddar, A.; Mazumder, C.

    2011-07-01

    We report the magnetic properties of nanosized Ni0.5Zn0.5Fe2O4 prepared by high-energy ball milling. We have characterized the sample by XRD, HRTEM, SQUID magnetometer and Mössbauer spectroscopic techniques. Sample exhibits superparamagnetic behaviour at room temperature. At 21 K the ferrimagnetic ordering and collective excitation along with a strong super-paramagnetic contribution give rise to a mixed magnetic phase. Our results show that magnetic property of the system is very sensitive to preparation technique adopted.

  6. Solvent-free and time-efficient Suzuki–Miyaura reaction in a ball mill: the solid reagent system KF–Al2O3 under inspection

    PubMed Central

    Bernhardt, Franziska; Trotzki, Ronald; Szuppa, Tony; Ondruschka, Bernd

    2010-01-01

    Summary Although a plethora of synthetic procedures mediated by KF-loaded aluminas is available in the literature, there is almost no data concerning the influence of parameters such as alumina modification or KF-loading on experimental results. Hence, the Pd-catalyzed, solvent-free Suzuki–Miyaura reaction was chosen as model reaction to investigate the effect of the above mentioned parameters on the results of coupling reactions. The results from ball milling experiments led to the conclusion that self-prepared and commercially available KF–Al2O3 differ in water content. The higher the residual water content, the higher are the product yields. PMID:20485589

  7. Mechanical and Microstructure Study of Nickel-Based ODS Alloys Processed by Mechano-Chemical Bonding and Ball Milling

    NASA Astrophysics Data System (ADS)

    Amare, Belachew N.

    Due to the need to increase the efficiency of modern power plants, land-based gas turbines are designed to operate at high temperature creating harsh environments for structural materials. The elevated turbine inlet temperature directly affects the materials at the hottest sections, which includes combustion chamber, blades, and vanes. Therefore, the hottest sections should satisfy a number of material requirements such as high creep strength, ductility at low temperature, high temperature oxidation and corrosion resistance. Such requirements are nowadays satisfied by implementing superalloys coated by high temperature thermal barrier coating (TBC) systems to protect from high operating temperature required to obtain an increased efficiency. Oxide dispersive strengthened (ODS) alloys are being considered due to their high temperature creep strength, good oxidation and corrosion resistance for high temperature applications in advanced power plants. These alloys operating at high temperature are subjected to different loading systems such as thermal, mechanical, and thermo-mechanical combined loads at operation. Thus, it is critical to study the high temperature mechanical and microstructure properties of such alloys for their structural integrity. The primary objective of this research work is to investigate the mechanical and microstructure properties of nickel-based ODS alloys produced by combined mechano-chemical bonding (MCB) and ball milling subjected to high temperature oxidation, which are expected to be applied for high temperature turbine coating with micro-channel cooling system. Stiffness response and microstructure evaluation of such alloy systems was studied along with their oxidation mechanism and structural integrity through thermal cyclic exposure. Another objective is to analyze the heat transfer of ODS alloy coatings with micro-channel cooling system using finite element analysis (FEA) to determine their feasibility as a stand-alone structural

  8. Structural; magnetic and catalytic properties of nanocrystalline Cu0.5Zn0.5Fe2O4 synthesized by microwave combustion and ball milling methods

    NASA Astrophysics Data System (ADS)

    Mahmoud, M. H.; Hassan, Azza M.; Said, Abd El-Aziz A.; Hamdeh, H. H.

    2016-06-01

    Effects of high energy ball-milling on nanosized Cu0.5Zn0.5Fe2O4 powders were studied at 30 and 330 min of milling. The powders were initially synthesized from its stoichiometric metal nitrates and urea mixtures, using a microwave assisted combustion method. Ball-milling induced electromechanical reaction was examined by XRD, TEM, Mössbauer spectroscopy, magnetization, and catalytic performance by exploring potential changes in size, phases and chemical structure. Before Milling, the as-prepared powders were comprised of small grains of poor spinel crystallinity and very small crystallite size, and a minor α-Fe2O3 phase. Progressive milling significantly reduced the grain size, increased chemical disorder, and reduced the hematite phase. These changes are also manifested in the magnetization measurements. The Catalytic activity performance was carried out using dehydrogenation of isopropyl alcohol. The observed activity was correlated to the presence of Cu2+ and Fe3+ catalysts at octahedral sites before and after milling.

  9. Characterization and x-ray absorption spectroscopy of ilmenite nanoparticles derived from natural ilmenite ore via acid-assisted mechanical ball-milling process

    NASA Astrophysics Data System (ADS)

    Phoohinkong, Weerachon; Pavasupree, Sorapong; Wannagon, Anucha; Sanguanpak, Samunya; Boonyarattanakalin, Kanokthip; Mekprasart, Wanichaya; Pecharapa, Wisanu

    2017-09-01

    In this work activated ilmenite nanoparticles were prepared by chemical-assisted in mechanical ball-milling process from ilmenite ore as starting raw material. The effect of milling process on their phase composition, particle size, surface morphology and local structure were investigated. Phase identification and crystalline structure of ilmenite mineral, milled samples and subsequent leached residues were characterized by x-ray diffraction (XRD). Meanwhile, the distorted octahedral structure and the oxidation state of relevant elements in ilmenite ore and activated ilmenite obtained by different process conditions were analyzed by x-ray absorption spectroscopy (XAS). Particle size and morphologies of the samples were monitored by field emission scanning electron microscope (FESEM) and transmission electron microscope (TEM). Three dominant peaks of TiO2 rutile, FeTiO3, and Fe2TiO4 are obviously adulterated in XRD patterns after mechanical milling with water and acid solution when comparing to precursor mineral. However, the contaminated phase of FeTiO3 and Fe2TiO4 was readily decreased by acid-assisted mechanical ball-milling. The enhancement in leaching process of ilmenite residue after milling can be obtained with sulfuric acid. This result suggests that iron contaminated phase could be leached from the sample resulting to the decrease in Fe environment around Ti atom. Invited talk at 5th Thailand International Nanotechnology Conference (Nano Thailand-2016), 27-29 November 2016, Nakhon Ratchasima, Thailand.

  10. Improved critical current density in ex situ processed MgB2 tapes by the size reduction of grains and crystallites by high-energy ball milling

    NASA Astrophysics Data System (ADS)

    Fujii, Hiroki; Ishitoya, Akira; Itoh, Shinji; Ozawa, Kiyoshi; Kitaguchi, Hitoshi

    2017-03-01

    We have fabricated Fe-sheathed MgB2 tapes through an ex situ process in a powder-in-tube (PIT) technique using powders ball milled under various conditions. Although the ex situ processed wires and tapes using the high-energy ball milled MgB2 powders have been studied and the decrease of grain and crystallite sizes of MgB2 and the critical current density (Jc) improvement of those conductors were reported so far, the use of filling powders milled at a higher rotation speed than previously reported further decreases the crystallite size and improves the Jc properties. The improved Jc values at 4.2 K and 10 T were nearly twice as large as those previously reported. Those milled powders and hence as-rolled tapes easily receive contamination in air. Thus, the transport Jc properties are easily deteriorated and scattered unless the samples are handled with care. The optimized heat treatment temperature (Topt) of those tape samples at which best performance in the Jc property is obtained decreases by more than 100 °C, compared with that of tapes using the as-received MgB2 powder.

  11. Formation of nanostructures in Ni-22Cr-11Fe-1X (X = Y2O3, TiO2) alloys by high-energy ball-milling.

    PubMed

    Park, Jiwhan; Jang, Jinsung; Kim, Tae Kyu; Kim, Sung-Jin; Ahn, Jung-Ho

    2011-07-01

    Powder mixtures of Ni, Cr, Fe and Y2O3 were high-energy ball-milled and subsequently sintered to fabricate Ni-based oxide-dispersion strengthened (ODS) alloys. Nano-sized Y2O3 and/or TiO2 seem to be dissolved in the Ni matrix forming a metastable solid solution during high-energy ball-milling or mechanical alloying (MA) process. The finely grained MA powders with high dislocation density facilitated the decomposition of oxides. The MA powders were consolidated to near-full density by spark plasma sintering at 1100 degrees C for 5 minutes in an Ar atmosphere. The Cr oxides as well as decomposed Y- and Ti-oxides thermally precipitated as oxide particles of several tens nanometers at this temperature, although sintering was carried out during a short time. The SPSed specimen showed a near full densification with almost pore-free microstructures. Examination of fractured surface showed a typical dimple rupture with fine and homogeneous distribution of dispersoids, indicating non-negligible room temperature ductility combined with high mechanical strength.

  12. Size effect on the melting temperature depression of Al12Mg17 complex metallic alloy nanoparticles prepared by planetary ball milling

    NASA Astrophysics Data System (ADS)

    Zolriasatein, Ashkan; Shokuhfar, Ali

    2015-11-01

    This research investigates the synthesis and size-dependent melting point depression of complex metallic alloy (CMA) nanoparticles. Al12Mg17 which belongs to this new category of intermetallic materials was initially produced as pre-alloyed ingot, then homogenized to achieve single phase compound and crushed into small size powder and finally, mechanically milled in a planetary ball mill to synthesize nanoparticles. Phase and microstructural characterizations of the as-crushed and milled powders were performed using X-ray diffractometry (XRD), field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). Effects of the mechanical milling on thermal behavior of the Al12Mg17 nanoparticles in comparison with as-cast Al12Mg17 ingot has been investigated by differential scanning calorimetry (DSC) measurement. It was found that an average particle size of 24 nm with crystallite size of 16 nm was achieved after 20 h of ball milling process. The size- dependent melting point depression of the Al12Mg17 nanoparticles has been experimentally observed and also comparison of the obtained results with theoretical models was carried out.

  13. Heterogeneous sono-Fenton-like process using martite nanocatalyst prepared by high energy planetary ball milling for treatment of a textile dye.

    PubMed

    Dindarsafa, Mahsa; Khataee, Alireza; Kaymak, Baris; Vahid, Behrouz; Karimi, Atefeh; Rahmani, Amir

    2017-01-01

    High energy planetary ball milling was applied to prepare sono-Fenton nanocatalyst from natural martite (NM). The NM samples were milled for 2-6h at the speed of 320rpm for production of various ball milled martite (BMM) samples. The catalytic performance of the BMMs was greater than the NM for treatment of Acid Blue 92 (AB92) in heterogeneous sono-Fenton-like process. The NM and the BMM samples were characterized by XRD, FT-IR, SEM, EDX and BET analyses. The particle size distribution of the 6h-milled martite (BMM3) was in the range of 10-90nm, which had the highest surface area compared to the other samples. Then, the impact of main operational parameters was investigated on the process. Complete removal of the dye was obtained at the desired conditions including initial pH 7, 2.5g/L BMM3 dosage, 10mg/L AB92 concentration, and 150W ultrasonic power after 30min of treatment. The treatment process followed pseudo-first order kinetic. Environmentally-friendly modification of the NM, low leached iron amount and repeated application at milder pH were the significant benefits of the BMM3. The GC-MS was successfully used to identify the generated intermediates. Eventually, an artificial neural network (ANN) was applied to predict the AB92 removal efficiency based upon the experimental data with a proper correlation coefficient (R(2)=0.9836).

  14. Crystal structure and magnetic properties of (Nd,Tb)2Fe14B nanoflakes prepared by surfactant-assisted ball milling

    NASA Astrophysics Data System (ADS)

    Li, Hongjian; Yue, Ming; Li, Yuqing; Wu, Qiong; Liu, Weiqiang; Zhang, Dongtao; Lu, Qingmei

    2017-05-01

    The microstructure, crystal structure, and magnetic properties were studied for (Nd,Tb)2Fe14B nanoflakes prepared by surfactant-assisted high-energy ball milling (HEBM). Effects of ball-milling time on the c-axis crystallographic alignment, morphology, and magnetic properties of (Nd,Tb)2Fe14B nanoflakes were systematically investigated. X-ray diffraction (XRD) results indicate that the average crystal grain size of the nanoflakes decreases from 60 nm of 1 hour milling to 33 nm of 7 hours milling. The nanoflakes milled for 3 hours bear an average thickness of 100 nm and an average diameter of 2 μm leading to a high aspect ratio of 20. In addition, the intensity ratio of I(006)/I(105) indicates that the degree of c-axis crystal texture increases first, peaks for 3 hours, then drops with increasing the milling time. Meanwhile, the coercivity (Hc) of the nanoflakes drops monotonically. The remanence (Mr) of nanoflakes milled for 3 hours in the easy axis direction is 11 kG, while the Mr in the hard axis direction is 1.8 kG, indicating a strong magnetic anisotropy. The optimal magnetic properties of Mr of 11 kG, and Hc of 7 kOe, (BH)max of 24.7 MGOe have been achieved.

  15. Nitrogen-doped graphene by all-solid-state ball-milling graphite with urea as a high-power lithium ion battery anode

    NASA Astrophysics Data System (ADS)

    Liu, Chao; Liu, Xingang; Tan, Jiang; Wang, Qingfu; Wen, Hao; Zhang, Chuhong

    2017-02-01

    Nitrogen-doped graphene nanosheets (NGNS) are prepared by a novel mechanochemical method via all-solid-state ball-milling graphite with urea. The ball-milling process does not only successfully exfoliate the graphite into multi-layer (<10 layers) graphene nanosheets, but at the same time, enables the N element to be doped onto the graphene. Urea, acting as a new solid doping and assist-grinding agents, has the advantages of low cost and good water solubility that can simplify the fabrication process. The as-prepared NGNS are investigated in detail by XRD, SEM, HRTEM, TGA, XPS and Raman spectroscopy. The doping nitrogens are around 3.15% and dominated (>94%) by pyrindic-N and pyrrolic-N which facilitates the NGNS with enhanced electronic conductivity and Li-ion storage capability. For the first time, we demonstrate that the all-solid-state prepared NGNS exhibits, especially at high currents, enhanced cycling stability and rate capability as Lithium ion battery (LIB) anode active material when compared to pristine graphite and undoped graphene in half-cell configuration. The method presented in this article may provide a simple, clean, economical and scalable strategy for preparation of NGNS as a feasible and promising anode material for LIBs.

  16. The Effect of High-energy Ball Milling on the Microstructure and Properties of Ti-doped MgB2 Bulks and Wires

    NASA Astrophysics Data System (ADS)

    Yang, F.; Yan, G.; Wang, Q. Y.; Xiong, X. M.; Li, S. Q.; liu, G. Q.; Feng, J. Q.; Pang, Y. C.; Li, C. S.; Feng, Y.; Zhang, P. X.

    MgB2 bulks were prepared by high-energy ball milling of Mg, B and Ti powders at ambient temperatures. The mixed powders were ball-milled for 0-10 h using a ball-to-powder mass ratio of 10 and sintered at 750 °C for 2 h. The phase and microstructure of MgB2 were characterized by means of X-ray diffraction (XRD) and Scanning electron microscope (SEM). XRD results reveal the appearance of a small amount of MgO impurity, and the relative percentage composition of MgO phase is gradually increased with prolonged the milling time. It proved that the sample milled 5 h has the best homogeneity in grain size. The milled 5 h powders were further processed to wires. The wire samples were fabricated by the in-situ powder-in-tube (PIT) method. The mechanical properties were analyzed by stress-strain measurements at room temperature and the superconducting behaviors are investigated by electrical tests at 4.2 K. The critical engineering current Ic reaches above 330 A (Jce exceeding 2.2×104 A/cm2) at 4.2 K and 2 T.

  17. Detailed Investigation of Ion Exchange in Ball Milled LiH+MgB2 System using Ultra-High Field NMR Spectroscopy

    SciTech Connect

    Hu, Jian Z.; Kwak, Ja Hun; Yang, Zhenguo; Wan, Xiufeng; Shaw, Leonard D.

    2010-06-01

    The present study with the detailed 1H-6Li cross polarization NMR analysis confirms the formation of a ternary compound, (Mg1-xLi2x)B2, during ball milling of LiH + ½ MgB2 at room temperature. The 6Li sites in (Mg1-xLi2x)B2 exhibit spinning sidebands (SSBs), whereas the 6Li sites in LiH do not. The SSBs and the very short spin-lattice relaxation time manifested by the 6Li sites in (Mg1-xLi2x)B2 indicate that the Li ions in (Mg1-xLi2x)B2 are located between the layered boron structures and close to Mg ions. The formation of (Mg1-xLi2x)B2 explains the previous observation that the LiH + ½ MgB2 mixture ball milled effectively has a greatly enhanced hydriding kinetics at temperatures below the melting point of LiBH4.

  18. Iron-based amorphous alloys and methods of synthesizing iron-based amorphous alloys

    DOEpatents

    Saw, Cheng Kiong; Bauer, William A.; Choi, Jor-Shan; Day, Dan; Farmer, Joseph C.

    2016-05-03

    A method according to one embodiment includes combining an amorphous iron-based alloy and at least one metal selected from a group consisting of molybdenum, chromium, tungsten, boron, gadolinium, nickel phosphorous, yttrium, and alloys thereof to form a mixture, wherein the at least one metal is present in the mixture from about 5 atomic percent (at %) to about 55 at %; and ball milling the mixture at least until an amorphous alloy of the iron-based alloy and the at least one metal is formed. Several amorphous iron-based metal alloys are also presented, including corrosion-resistant amorphous iron-based metal alloys and radiation-shielding amorphous iron-based metal alloys.

  19. Calorimetry study of the synthesis of amorphous Ni-Ti alloys by mechanical alloying. [Ni33 Ti67

    SciTech Connect

    Schwarz, R.B.; Petrich, R.R.

    1988-01-01

    We synthesized amorphous Ni/sub 33/Ti/sub 67/ alloy powder by ball milling (a) a mixture of elemental nickel and titanium powders and (b) powders of the crystalline intermetallic NiTi/sub 2/. We characterized the reaction products as a function of ball-milling time by differential scanning calorimetry and x-ray diffraction. The measurements suggest that in process (a) the amorphous alloy forms by a solid-state interdiffusion reaction at the clean Ni/Ti interfaces generated by the mechanical attrition. In process (b), the crystalline alloy powder stores energy in the form of chemical disorder and lattice and point defects. The crystal-to-amorphous transformation occurs when the stored energy reaches a critical value. The achievement of the critical stored energy competes with the dynamic recovery of the lattice. 23 refs., 7 figs.

  20. Contamination Effects on Improving the Hydrogenation/Dehydrogenation Kinetics of Binary Magnesium Hydride/Titanium Carbide Systems Prepared by Reactive Ball Milling.

    PubMed

    El-Eskandarany, M Sherif; Shaban, Ehab

    2015-10-10

    Ultrafine MgH₂ nanocrystalline powders were prepared by reactive ball milling of elemental Mg powders after 200 h of high-energy ball milling under a hydrogen gas pressure of 50 bar. The as-prepared metal hydride powders were contaminated with 2.2 wt. % of FeCr-stainless steel that was introduced to the powders upon using stainless steel milling tools made of the same alloy. The as-synthesized MgH₂ was doped with previously prepared TiC nanopowders, which were contaminated with 2.4 wt. % FeCr (materials of the milling media), and then ball milled under hydrogen gas atmosphere for 50 h. The results related to the morphological examinations of the fabricated nanocomposite powders beyond the micro-and nano-levels showed excellent distributions of 5.2 wt. % TiC/4.6 wt. % FeCr dispersoids embedded into the fine host matrix of MgH₂ powders. The as-fabricated nanocomposite MgH₂/5.2 wt. % TiC/4.6 wt. % FeCr powders possessed superior hydrogenation/dehydrogenation characteristics, suggested by the low value of the activation energy (97.74 kJ/mol), and the short time required for achieving a complete absorption (6.6 min) and desorption (8.4 min) of 5.51 wt. % H₂ at a moderate temperature of 275 °C under a hydrogen gas pressure ranging from 100 mbar to 8 bar. van't Hoff approach was used to calculate the enthalpy (DH) and entropy (DS) of hydrogenation for MgH₂, which was found to be -72.74 kJ/mol and 112.79 J/mol H₂/K, respectively. Moreover, van't Hoff method was employed to calculate the DH and DS of dehydrogenation, which was found to be 76.76 kJ/mol and 119.15 J/mol H₂/K, respectively. This new nanocomposite system possessed excellent absorption/desorption cyclability of 696 complete cycles, achieved in a cyclic-life-time of 682 h.

  1. Contamination Effects on Improving the Hydrogenation/Dehydrogenation Kinetics of Binary Magnesium Hydride/Titanium Carbide Systems Prepared by Reactive Ball Milling

    PubMed Central

    El-Eskandarany, M. Sherif; Shaban, Ehab

    2015-01-01

    Ultrafine MgH2 nanocrystalline powders were prepared by reactive ball milling of elemental Mg powders after 200 h of high-energy ball milling under a hydrogen gas pressure of 50 bar. The as-prepared metal hydride powders were contaminated with 2.2 wt. % of FeCr-stainless steel that was introduced to the powders upon using stainless steel milling tools made of the same alloy. The as-synthesized MgH2 was doped with previously prepared TiC nanopowders, which were contaminated with 2.4 wt. % FeCr (materials of the milling media), and then ball milled under hydrogen gas atmosphere for 50 h. The results related to the morphological examinations of the fabricated nanocomposite powders beyond the micro-and nano-levels showed excellent distributions of 5.2 wt. % TiC/4.6 wt. % FeCr dispersoids embedded into the fine host matrix of MgH2 powders. The as-fabricated nanocomposite MgH2/5.2 wt. % TiC/4.6 wt. % FeCr powders possessed superior hydrogenation/dehydrogenation characteristics, suggested by the low value of the activation energy (97.74 kJ/mol), and the short time required for achieving a complete absorption (6.6 min) and desorption (8.4 min) of 5.51 wt. % H2 at a moderate temperature of 275 °C under a hydrogen gas pressure ranging from 100 mbar to 8 bar. van’t Hoff approach was used to calculate the enthalpy (∆H) and entropy (∆S) of hydrogenation for MgH2, which was found to be −72.74 kJ/mol and 112.79 J/mol H2/K, respectively. Moreover, van’t Hoff method was employed to calculate the ΔH and ΔS of dehydrogenation, which was found to be 76.76 kJ/mol and 119.15 J/mol H2/K, respectively. This new nanocomposite system possessed excellent absorption/desorption cyclability of 696 complete cycles, achieved in a cyclic-life-time of 682 h. PMID:28793606

  2. Recycling process for recovery of gallium from GaN an e-waste of LED industry through ball milling, annealing and leaching

    SciTech Connect

    Swain, Basudev Mishra, Chinmayee; Kang, Leeseung; Park, Kyung-Soo Lee, Chan Gi; Hong, Hyun Seon

    2015-04-15

    Waste dust generated during manufacturing of LED contains significant amounts of gallium and indium, needs suitable treatment and can be an important resource for recovery. The LED industry waste dust contains primarily gallium as GaN. Leaching followed by purification technology is the green and clean technology. To develop treatment and recycling technology of these GaN bearing e-waste, leaching is the primary stage. In our current investigation possible process for treatment and quantitative leaching of gallium and indium from the GaN bearing e-waste or waste of LED industry dust has been developed. To recycle the waste and quantitative leaching of gallium, two different process flow sheets have been proposed. In one, process first the GaN of the waste the LED industry dust was leached at the optimum condition. Subsequently, the leach residue was mixed with Na{sub 2}CO{sub 3}, ball milled followed by annealing, again leached to recover gallium. In the second process, the waste LED industry dust was mixed with Na{sub 2}CO{sub 3}, after ball milling and annealing, followed acidic leaching. Without pretreatment, the gallium leaching was only 4.91 w/w % using 4 M HCl, 100 °C and pulp density of 20 g/L. After mechano-chemical processing, both these processes achieved 73.68 w/w % of gallium leaching at their optimum condition. The developed process can treat and recycle any e-waste containing GaN through ball milling, annealing and leaching. - Highlights: • Simplest process for treatment of GaN an LED industry waste developed. • The process developed recovers gallium from waste LED waste dust. • Thermal analysis and phase properties of GaN to Ga{sub 2}O{sub 3} and GaN to NaGaO{sub 2} revealed. • Solid-state chemistry involved in this process reported. • Quantitative leaching of the GaN was achieved.

  3. Use of cellobiohydrolase-free cellulase blends for the hydrolysis of microcrystalline cellulose and sugarcane bagasse pretreated by either ball milling or ionic liquid [Emim][Ac].

    PubMed

    Teixeira, Ricardo Sposina Sobral; da Silva, Ayla Sant'Ana; Kim, Han-Woo; Ishikawa, Kazuhiko; Endo, Takashi; Lee, Seung-Hwan; Bon, Elba P S

    2013-12-01

    This study investigated the requirement of cellobiohydrolases (CBH) for saccharification of microcrystalline cellulose and sugarcane bagasse pretreated either by ball milling (BM) or by ionic liquid (IL) [Emim][Ac]. Hydrolysis was done using CBH-free blends of Pyrococcus horikoshii endoglucanase (EG) plus Pyrococcus furiosus β-glucosidase (EGPh/BGPf) or Optimash™ BG while Acremonium Cellulase was used as control. IL-pretreated substrates were hydrolyzed more effectively by CBH-free enzymes than were the BM-pretreated substrates. IL-treatment decreased the crystallinity and increased the specific surface area (SSA), whereas BM-treatment decreased the crystallinity without increasing the SSA. The hydrolysis of IL-treated cellulose by EGPh/BGPf showed a saccharification rate of 3.92 g/Lh and a glucose yield of 81% within 9h. These results indicate the efficiency of CBH-free enzymes for the hydrolysis of IL-treated substrates.

  4. The Structure and Mechanical Properties of High-Strength Bulk Ultrafine-Grained Cobalt Prepared Using High-Energy Ball Milling in Combination with Spark Plasma Sintering

    PubMed Central

    Marek, Ivo; Vojtěch, Dalibor; Michalcová, Alena; Kubatík, Tomáš František

    2016-01-01

    In this study, bulk ultrafine-grained and micro-crystalline cobalt was prepared using a combination of high-energy ball milling and subsequent spark plasma sintering. The average grain sizes of the ultrafine-grained and micro-crystalline materials were 200 nm and 1 μm, respectively. Mechanical properties such as the compressive yield strength, the ultimate compressive strength, the maximum compressive deformation and the Vickers hardness were studied and compared with those of a coarse-grained as-cast cobalt reference sample. The bulk ultrafine-grained sample showed an ultra-high compressive yield strength that was greater than 1 GPa, which is discussed with respect to the preparation technique and a structural investigation. PMID:28773514

  5. Structure-Property Correlation in Fe-Al2O3 In Situ Nanocomposite Synthesized by High-Energy Ball Milling and Spark Plasma Sintering

    NASA Astrophysics Data System (ADS)

    Udhayabanu, V.; Ravi, K. R.; Murty, B. S.

    2016-10-01

    In the present study, Fe-10 vol pct Al2O3 in situ nanocomposite has been derived by high-energy ball milling of Fe2O3-Fe-Al powder mixture followed by the consolidation using spark plasma sintering (SPS). The consolidated nanocomposite has bimodal-grained structure consisting of nanometer- and submicron-sized Fe grains along with nanometer-sized Al2O3, and Fe3O4 particles. The mechanical property analysis reveals that compressive yield strength of Fe-10 vol pct Al2O3 nanocomposite is 2100 MPa which is nearly two times higher than that of monolithic Fe processed by Mechanical Milling and SPS. The strengthening contributions obtained from matrix, grain size, and particles in the synthesized nanocomposite have been calculated theoretically, and are found to be matching well with the experimental strength levels.

  6. Effect of ball milling and thermal treatment on exchange bias and magnetocaloric properties of Ni48Mn39.5Sn10.5Al2 ribbons

    NASA Astrophysics Data System (ADS)

    Czaja, P.; Przewoźnik, J.; Fitta, M.; Bałanda, M.; Chrobak, A.; Kania, B.; Zackiewicz, P.; Wójcik, A.; Szlezynger, M.; Maziarz, W.

    2016-03-01

    The combined effect of ball milling and subsequent heat treatment on microstructure, magnetic, magnetocaloric and exchange bias properties of Ni48Mn39.5Sn10.5Al2 ribbons is reported. The annealing treatment results in the increase of the critical martensitic transformation temperature. The magnetic entropy change ΔSM of the order of 7.9 and -2.3 J kg K-1 for the annealed 50-32 μm powder fraction is determined. This is less than in the as melt spun ribbon but appears at a considerably higher temperature. At the same time EB is decreased due to annealing treatment. This decrease is attributed to the strengthened ferromagnetic exchange coupling due heat induced stress and structural relaxation.

  7. Ultrathin SmCo5 nanoflakes with high-coercivity prepared by solid particle (NaCl) and surfactant co-assisted ball milling

    NASA Astrophysics Data System (ADS)

    Zuo, Wen-Liang; Zhao, Xin; Zhao, Tong-Yun; Hu, Feng-Xia; Sun, Ji-Rong; Shen, Bao-Gen

    2016-05-01

    The ultrathin SmCo5 nanoflakes with average thickness smaller than 50 nm are prepared by a novel method of solid particle (NaCl) and surfactant co-assisted ball milling. The as-prepared nanoflakes exhibit a narrower thickness distribution of 10–50 nm and high coercivity of 23 kOe. The possible formation mechanism of nanoflakes are proposed. Temperature dependence of demagnetization curves indicate that the magnetization reversal may be controlled by both nucleation and pinning. The results of X-ray powder diffraction and magnetic measurement for aligned SmCo5 nanoflakes resin composite indicate that the nanoflakes have a high texture degree. The ultrathin thickness and high coercivity are beneficial for preparing the high performance soft/hard coupling magnets and nanocomposite magnets.

  8. Layered-Layered-Spinel Cathode Materials Prepared by a High-Energy Ball-Milling Process for Lithium-ion Batteries.

    PubMed

    Kim, Soo; Noh, Jae-Kyo; Aykol, Muratahan; Lu, Zhi; Kim, Haesik; Choi, Wonchang; Kim, Chunjoong; Chung, Kyung Yoon; Wolverton, Chris; Cho, Byung-Won

    2016-01-13

    In this work, we report the electrochemical properties of 0.5Li2MnO3·0.25LiNi0.5Co0.2Mn0.3O2·0.25LiNi0.5Mn1.5O4 and 0.333Li2MnO3·0.333LiNi0.5Co0.2Mn0.3O2·0.333LiNi0.5Mn1.5O4 layered-layered-spinel (L*LS) cathode materials prepared by a high-energy ball-milling process. Our L*LS cathode materials can deliver a large and stable capacity of ∼200 mAh g(-1) at high voltages up to 4.9 V, and do not show the anomalous capacity increase upon cycling observed in previously reported three-component cathode materials synthesized with different routes. Furthermore, we have performed synchrotron-based in situ X-ray diffraction measurements and found that there are no significant structural distortions during charge/discharge runs. Lastly, we carry out (opt-type) van der Waals-corrected density functional theory (DFT) calculations to explain the enhanced cycle characteristics and reduced phase transformations in our ball-milled L*LS cathode materials. Our simple synthesis method brings a new perspective on the use of the high-power L*LS cathodes in practical devices.

  9. Diamagnetic, paramagnetic, and ferromagnetic properties of ball milled Bi_{1.65}Pb_{0.35}Sr2Ca2Cu3O_{10+δ } powders

    NASA Astrophysics Data System (ADS)

    Govea-Alcaide, E.; Pérez-Acosta, L.; Kiyohara, P. K.; Jardim, R. F.

    2015-11-01

    We have performed a systematic study of the general physical properties of (Bi,Pb)_2Sr_2Ca_2Cu_{10+y} (Bi-2223) powders that were ball milled for time intervals of up to tm = 210 min. X-ray powder diffraction diagrams indicate that the phase composition of the samples seems to be preserved after the ball milling process, but the average grain size of the samples decreases appreciably with increasing milling time tm. For tm = 120 min, the transmission electron microscopy (TEM) images revealed the presence of Bi-2223 grains in the form of nanorods with a mean diameter of dg ˜ 20 nm. The temperature dependence of the magnetic susceptibility, χ (T), showed the occurrence of superconductivity below Tc ˜ 108 K in all samples studied and a progressive decrease of the diamagnetic contribution to χ (T) with increasing tm. Such a decrease in the diamagnetic contribution to χ (T) is accompanied by an increase of a paramagnetic contribution that has its origin in a disordered shell of the milled grains. Increasing tm results in a progressive increase of the width of disordered shell further increasing the paramagnetic contribution to χ (T) that shows a very small diamagnetic component in samples subjected to large milling times. We have also found that the occurrence of oxygen vacancies in the disordered shell is responsible for a ferromagnetic contribution to χ (T) at high temperatures. Such a shell-core morphology of the milled grains, comprising a superconducting and diamagnetic core and a disordered and paramagnetic shell, is sufficient for interpreting the magnetic properties of the samples.

  10. An X-Ray Absorption Spectroscopy Study of Ball-Milled Lithium Tantalate and Lithium Titanate Nanocrystals

    NASA Astrophysics Data System (ADS)

    Chadwick, A. V.; Pickup, D. M.; Ramos, S.; Cibin, G.; Tapia-Ruiz, N.; Breuer, S.; Wohlmuth, D.; Wilkening, M.

    2017-02-01

    Previous work has shown that nanocrystalline samples of lithium tantalate and titanate prepared by high-energy milling show unusually high lithium ion conductivity. Here, we report an X-ray absorption spectroscopy (XAS) study at the Ti K-edge and the Ta L3 edge of samples that have been milled for various lengths of time. For both systems the results show that milling creates amorphous material whose quantity increases with the milling time. The more extensive data for the tantalate shows that milling for only 30 minutes generates ∼25% amorphous content in the sample. The content rises to ∼60% after 16 hours. It is suggested that it is the motion of the lithium ions through the amorphous content that provides the mechanism for the high ionic conductivity.

  11. Solid state amorphization in the Al-Fe binary system during high energy milling

    SciTech Connect

    Urban, P. Montes, J. M.; Cintas, J.

    2013-12-16

    In the present study, mechanical alloying (MA) of Al75Fe25 elemental powders mixture was carried out in argon atmosphere, using a high energy attritor ball mill. The microstructure of the milled products at different stages of milling was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and differential scanning calorimetry (DSC). The results showed that the amorphous phase content increased by increasing the milling time, and after 50 hours the amorphization process became complete. Heating the samples resulted in the crystallization of the synthesized amorphous alloys and the appearance of the equilibrium intermetallic compounds Al{sub 5}Fe{sub 2}.

  12. Phase transformations in amorphous fullerite C60 under high pressure and high temperature

    NASA Astrophysics Data System (ADS)

    Borisova, P. A.; Blanter, M. S.; Brazhkin, V. V.; Somenkov, V. A.; Filonenko, V. P.

    2015-08-01

    First phase transformations of amorphous fullerite C60 at high temperatures (up to 1800 K) and high pressures (up to 8 GPa) have been investigated and compared with the previous studies on the crystalline fullerite. The study was conducted using neutron diffraction and Raman spectroscopy. The amorphous fullerite was obtained by ball-milling. We have shown that under thermobaric treatment no crystallization of amorphous fullerite into С60 molecular modification is observed, and it transforms into amorphous-like or crystalline graphite. A kinetic diagram of phase transformation of amorphous fullerite in temperature-pressure coordinates was constructed for the first time. Unlike in crystalline fullerite, no crystalline polymerized phases were formed under thermobaric treatment on amorphous fullerite. We found that amorphous fullerite turned out to be less resistant to thermobaric treatment, and amorphous-like or crystalline graphite were formed at lower temperatures than in crystalline fullerite.

  13. Co-Amorphous Combination of Nateglinide-Metformin Hydrochloride for Dissolution Enhancement.

    PubMed

    Wairkar, Sarika; Gaud, Ram

    2016-06-01

    The aim of the present work was to prepare a co-amorphous mixture (COAM) of Nateglinide and Metformin hydrochloride to enhance the dissolution rate of poorly soluble Nateglinide. Nateglinide (120 mg) and Metformin hydrochloride (500 mg) COAM, as a dose ratio, were prepared by ball-milling technique. COAMs were characterized for saturation solubility, amorphism and physicochemical interactions (X-ray powder diffraction (XRPD), differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR)), SEM, in vitro dissolution, and stability studies. Solubility studies revealed a sevenfold rise in solubility of Nateglinide from 0.061 to 0.423 mg/ml in dose ratio of COAM. Solid-state characterization of COAM suggested amorphization of Nateglinide after 6 h of ball milling. XRPD and DSC studies confirmed amorphism in Nateglinide, whereas FTIR elucidated hydrogen interactions (proton exchange between Nateglinide and Metformin hydrochloride). Interestingly, due to low energy of fusion, Nateglinide was completely amorphized and stabilized by Metformin hydrochloride. Consequently, in vitro drug release showed significant increase in dissolution of Nateglinide in COAM, irrespective of dissolution medium. However, little change was observed in the solubility and dissolution profile of Metformin hydrochloride, revealing small change in its crystallinity. Stability data indicated no traces of devitrification in XRPD of stability sample of COAM, and % drug release remained unaffected at accelerated storage conditions. Amorphism of Nateglinide, proton exchange with Metformin hydrochloride, and stabilization of its amorphous form have been noted in ball-milled COAM of Nateglinide-Metformin hydrochloride, revealing enhanced dissolution of Nateglinide. Thus, COAM of Nateglinide-Metformin hydrochloride system is a promising approach for combination therapy in diabetic patients.

  14. Solid state amorphization kinetic of alpha lactose upon mechanical milling.

    PubMed

    Caron, Vincent; Willart, Jean-François; Lefort, Ronan; Derollez, Patrick; Danède, Florence; Descamps, Marc

    2011-11-29

    It has been previously reported that α-lactose could be totally amorphized by ball milling. In this paper we report a detailed investigation of the structural and microstructural changes by which this solid state amorphization takes place. The investigations have been performed by Powder X-ray Diffraction, Solid State Nuclear Magnetic Resonance ((13)C CP-MAS) and Differential Scanning Calorimetry. The results reveal the structural complexity of the material in the course of its amorphization so that it cannot be considered as a simple mixture made of a decreasing crystalline fraction and an increasing amorphous fraction. Heating this complexity can give rise to a fully nano-crystalline material. The results also show that chemical degradations upon heating are strongly connected to the melting process.

  15. CROSS-DISCIPLINARY PHYSICS AND RELATED AREAS OF SCIENCE AND TECHNOLOGY: Effects of Raw Material Content on Efficiency of TiN Synthesized by Reactive Ball Milling Ti and Urea

    NASA Astrophysics Data System (ADS)

    Sun, Jin-Feng; Li, Xiao-Pu; Liang, Bao-Yan; Zhao, Yu-Cheng; Wang, Ming-Zhi

    2009-07-01

    Ti and urea mixed according to the molar ratios of 2:1, 3:1 and 4:1 are milled under the same condition. The structures of the as-synthesized powders are analyzed by an x-ray diffractometer (XRD). The decomposed temperature of the urea and the products decomposed are characterized by differential scanning calorimetry (DSC) and thermogravimetry analysis-Fourier transform infrared (TG-FTIR) spectrometry. The results show that the reaction progress is a diffusion reaction. The efficiency of TiN synthesized by reactive ball milling can be increased by increasing the content of Ti. The reactive ball milling time decreases from more than 90 h to 40 h corresponding to the content ratio between Ti and urea increasing from 2:1 to 4:1. Ammonia gas (NH3) and cyanic acid (HNCO), the decomposed products of urea, react with the refined Ti to form TiN. The grain refinement of Ti has a significant effect on the efficiency of reactive ball milling.

  16. Effect of ball-milling and Fe-/Al-doping on the structural aspect and visible light photocatalytic activity of TiO2 towards Escherichia coli bacteria abatement.

    PubMed

    Schlur, Laurent; Begin-Colin, Sylvie; Gilliot, Pierre; Gallart, Mathieu; Carré, Gaëlle; Zafeiratos, Spiros; Keller, Nicolas; Keller, Valérie; André, Philippe; Greneche, Jean-Marc; Hezard, Bernard; Desmonts, Marie-Hélène; Pourroy, Geneviève

    2014-05-01

    Escherichia coli abatement was studied in liquid phase under visible light in the presence of two commercial titania photocatalysts, and of Fe- and Al-doped titania samples prepared by high energy ball-milling. The two commercial titania photocatalysts, Aeroxide P25 (Evonik industries) exhibiting both rutile and anatase structures and MPT625 (Ishihara Sangyo Kaisha), a Fe-, Al-, P- and S-doped titania exhibiting only the rutile phase, are active suggesting that neither the structure nor the doping is the driving parameter. Although the MPT625 UV-visible spectrum is shifted towards the visible domain with respect to the P25 one, the effect on bacteria is not increased. On the other hand, the ball milled iron-doped P25 samples exhibit low activities in bacteria abatement under visible light due to charge recombinations unfavorable to catalysis as shown by photoluminescence measurements. While doping elements are in interstitial positions within the rutile structure in MPT625 sample, they are located at the surface in ball milled samples and in isolated octahedral units according to (57)Fe Mössbauer spectrometry. The location of doping elements at the surface is suggested to be responsible for the sample cytotoxicity observed in the dark. Copyright © 2014 Elsevier B.V. All rights reserved.

  17. Magneto-optical properties of α-Fe2O3@ZnO nanocomposites prepared by the high energy ball-milling technique

    NASA Astrophysics Data System (ADS)

    Chaudhury, Chandana Roy; Roychowdhury, Anirban; Das, Anusree; Das, Dipankar

    2016-05-01

    Magnetic-fluorescent nanocomposites (NCs) with 10 wt% of α-Fe2O3 in ZnO have been prepared by the high energy ball-milling. The crystallite sizes of α-Fe2O3 and ZnO in the NCs are found to vary from 65 nm to 20 nm and 47 nm to 15 nm respectively as milling time is increased from 2 to 30 h. XRD analysis confirms presence of α-Fe2O3 and ZnO in pure form in all the NCs. UV-vis study of the NCs shows a continuous blue-shift of the absorption peak and a steady increase of band gap of ZnO with increasing milling duration that are assigned to decreasing particle size of ZnO in the NCs. Photoluminescence (PL) spectra of the NCs reveal three weak emission bands in the visible region at 421, 445 and 485 nm along with the strong near band edge emission at 391 nm. These weak emission bands are attributed to different defect - related energy levels e.g. Zn-vacancy, Zn interstitial and oxygen vacancy. Dc and ac magnetization measurements show presence of weakly interacting superparamagnetic (SPM) α-Fe2O3 particles in the NCs. 57Fe-Mössbauer study confirms presence of SPM hematite in the sample milled for 30 h. Positron annihilation lifetime measurements indicate presence of cation vacancies in ZnO nanostructures confirming results of PL studies.

  18. Influence of ball milling and annealing conditions on the properties of L10 FePt nanoparticles fabricated by a new green chemical synthesis method

    NASA Astrophysics Data System (ADS)

    Hu, X. C.; Capobianchi, A.; Gallagher, R.; Hadjipanayis, G. C.

    2014-05-01

    In this work, a new green chemical strategy for the synthesis of L10 FePt alloy nanoparticles is reported. The precursor is a polycrystalline molecular complex (Fe(H2O)6PtCl6), in which Fe and Pt atoms are arranged on alternating planes and milled with NaCl to form nanocrystals. Then the mixture was annealed under reducing atmosphere (5% H2 and 95% Ar) at temperatures varying from 350 °C to 500 °C for 2 h with a heating rate of 5 °C/min. After the reduction, the mixture was washed with water to remove the NaCl and L10 FePt nanoparticles were obtained. The X-Ray Diffraction pattern showed the presence of the characteristic peaks of the fct phase of FePt nanoparticles. Influence of precursor/NaCl ratio and ball milling time on particle size was investigated. Transmission electron microscopy images revealed that smaller precursor/NaCl ratio (10 mg/20 g) and longer milling time (15 h) lead to smaller particle size and narrower size distribution. Milling time does not influence the coercivity much but the decrease of the amount of precursor leads to a decrease of coercivity from 10.8 kOe to 4.8 kOe.

  19. Binding of carbon coated nano-silicon in graphene sheets by wet ball-milling and pyrolysis as high performance anodes for lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Sun, Wei; Hu, Renzong; Zhang, Miao; Liu, Jiangwen; Zhu, Min

    2016-06-01

    A novel approach has been developed to prepare silicon@carbon/graphene sheets (Si@C/G) composite with a unique structure, in which carbon coated Si nanoparticles are uniformly dispersed in a matrix of graphene sheets, to enhance the cycleability and electronic conductivity of Si-based anodes for Li-ion batteries. In this study, Si nanoparticles and expanded graphite (EG) are treated by combining high-energy wet ball-milling in sucrose solution with subsequent pyrolysis treatment to produce this Si@C/G composite. To achieve better overall electrochemical performance, the carbon content of the composites is also studied systematically. The as-designed Si30@C40/G30 (Si:C:G = 30:40:30, by weight) composite exhibits a high Li-storage capacity of 1259 mAh g-1 at a current density of 0.2 A g-1 in the first cycle. Further, a stable cycleability with 99.1/88.2% capacity retention from initial reversible charge capacity can be achieved over 100/300 cycles, showing great promise for batteries applications. This good electrochemical performance can be attributed to the uniform coating and binding effect of pyrolytic carbon as well as the network of graphene sheets, which increase the electronic conductivity and Li+ diffusion in the composite, and effectively accommodated the volume change of Si nanoparticles during the Li+ alloying and dealloying processes.

  20. Effect of the method of introduction of Y2O3 into NiAl-based powder alloys on their structure: I. Agitation in a ball mill

    NASA Astrophysics Data System (ADS)

    Povarova, K. B.; Vershinina, T. N.; Skachkov, O. A.; Drozdov, A. A.; Morozov, A. E.; Pozharov, S. V.

    2012-09-01

    The effect of the sintering temperature (1100-1400°C) of NiAl alloy samples with oxide Y2O3 produced by hydrostatic pressing on their structure and phase composition and the distribution of oxide particles in a NiAl-based intermetallic matrix alloyed with ˜0.5 at % Fe is considered. It is found that dispersed oxide particles in the compact material prepared from a mixture of oxide Y2O3 powder and a NiAl alloy (produced by calcium hydride reduction of a mixture of nickel and aluminum oxides) powder in a standard ball mill are nonuniformly distributed in the volume. The morphology of oxides changes during sintering: sintered samples contain rounded particles, which differ strongly from the clearly faceted angular particles of oxide Y2O3 added to a mixture (they represent conglomerates of single crystals). In the sintered samples, large aggregates of oxides are revealed along grain boundaries. Mass transfer is possible at the NiAl/Y2O3 interface in the system: it leads to partial substitution of aluminum and/or iron atoms for yttrium atoms in the Y2O3 lattice and to the formation of submicroscopic particles of (Fe,Al)5Y3O12-type oxides.

  1. Preparation of TiO2-Decorated Boron Particles by Wet Ball Milling and their Photoelectrochemical Hydrogen and Oxygen Evolution Reactions

    PubMed Central

    Jung, Hye Jin; Nam, Kyusuk; Sung, Hong-Gye; Hyun, Hyung Soo; Sohn, Youngku; Shin, Weon Gyu

    2016-01-01

    TiO2-coated boron particles were prepared by a wet ball milling method, with the particle size distribution and average particle size being easily controlled by varying the milling operation time. Based on the results from X-ray photoelectron spectroscopy, transmission electron microscopy, energy dispersive X-ray analysis, and Fourier transform infrared spectroscopy, it was confirmed that the initial oxide layer on the boron particles surface was removed by the wet milling process, and that a new B–O–Ti bond was formed on the boron surface. The uniform TiO2 layer on the 150 nm boron particles was estimated to be 10 nm thick. Based on linear sweep voltammetry, cyclic voltammetry, current-time amperometry, and electrochemical impedance analyses, the potential for the application of TiO2-coated boron particles as a photoelectrochemical catalyst was demonstrated. A current of 250 μA was obtained at a potential of 0.5 V for hydrogen evolution, with an onset potential near to 0.0 V. Finally, a current of 220 μA was obtained at a potential of 1.0 V for oxygen evolution. PMID:28774132

  2. Enhanced coercivity and remanence of PrCo5 nanoflakes prepared by surfactant-assisted ball milling with heat-treated starting powder

    NASA Astrophysics Data System (ADS)

    Zuo, Wen-Liang; Zhao, Xin; Xiong, Jie-Fu; Shang, Rong-Xiang; Zhang, Ming; Hu, Feng-Xia; Sun, Ji-Rong; Shen, Bao-Gen

    2015-07-01

    PrCo5 nanoflakes with strong texture and high coercivity of 8.15 kOe were prepared by surfactant-assisted ball milling with heat-treated starting powder. The thickness and length of the as-milled nanoflakes are mainly in the ranges of 50-100 nm and 0.5-3 μm, respectively. The x-ray diffraction patterns demonstrate that the heat treatment can increase the single phase and crystallinity of the PrCo5 compound, and combined with the demagnetization curves, indicate that the single phase and crystallinity are important for preparing high-coercivity and strong-textured rare earth permanent magnetic nanoflakes. In addition, the coercivity mechanism of the as-milled PrCo5 nanoflakes is studied by the angle dependence of coercivity for an aligned sample and the field dependence of coercivity, isothermal (IRM) and dc demagnetizing (DCD) remanence curves for an unaligned sample. The results indicate that the coercivity is dominated by co-existing mechanisms of pinning and nucleation. Furthermore, exchange coupling and dipolar coupling also co-exist in the sample. Project supported by the National Basic Research Program of China (Grant No. 2014CB643702), the National Natural Science Foundation of China (Grant No. 51401235), and Beijing Natural Science Foundation, China (Grant No. 2152034).

  3. Textured Pr{sub 2}Fe{sub 14}B flakes with submicron or nanosize thickness prepared by surfactant-assisted ball milling

    SciTech Connect

    Zuo, Wen-Liang E-mail: shenbg@aphy.iphy.ac.cn; Liu, Rong-Ming; Zheng, Xin-Qi; Wu, Rong-Rong; Hu, Feng-Xia; Sun, Ji-Rong; Shen, Bao-Gen E-mail: shenbg@aphy.iphy.ac.cn

    2014-05-07

    The textured Pr{sub 2}Fe{sub 14}B nanoflakes were produced by surfactant-assisted ball milling (SABM). Single phase tetragonal structure was characterized for the samples before and after SABM by X-ray diffraction (XRD). The thickness and length of the as-milled flakes are mainly in the range of 50–150 nm and 0.5–2 μm, respectively. For the field-aligned Pr{sub 2}Fe{sub 14}B nanoflakes, the out-of-plane texture (the easy magnetization direction (EMD) along the c-axis) is indicated from the increasing (00l) peaks in the XRD patterns. SEM image demonstrates that the EMD is parallel to flaky surface, which is different from the RCo{sub 5} (R = rare earth) system with EMD perpendicular to the surface. We propose a hypothesis that the easy glide planes are related with the area of crystal planes. In addition, a large coercivity H{sub c} = 3.9 kOe is observed in the Pr{sub 2}Fe{sub 14}B flakes with strong texture.

  4. Effect of ball milling and dynamic compaction on magnetic properties of Al{sub 2}O{sub 3}/Co(P) composite particles

    SciTech Connect

    Denisova, E. A.; Kuzovnikova, L. A.; Iskhakov, R. S. Eremin, E. V.; Bukaemskiy, A. A.; Nemtsev, I. V.

    2014-05-07

    The evolution of the magnetic properties of composite Al{sub 2}O{sub 3}/Co(P) particles during ball milling and dynamic compaction is investigated. To prepare starting composite particles, the Al{sub 2}O{sub 3} granules were coated with a Co{sub 95}P{sub 5} shell by electroless plating. The magnetic and structural properties of the composite particles are characterized by scanning electron microscopy, X-ray diffraction, and the use of the Physical Property Measurement System. The use of composite core-shell particles as starting powder for mechanoactivation allows to decrease treatment duration to 1 h and to produce a more homogeneous bulk sample than in the case of the mixture of Co and Al{sub 2}O{sub 3} powders. The magnetic properties of the milled composite particles are correlated with changes in the microstructure. Reduction in grain size of Co during milling leads to an increase of the volume fraction of superparamagnetic particles and to a decrease of the saturation magnetization. The local magnetic anisotropy field depends on the amount of hcp-Co phase in sample. The anisotropy field value decreases from 8.4 kOe to 3.8 kOe with an increase in milling duration up to 75 min. The regimes of dynamic compaction were selected so that the magnetic characteristics—saturation magnetization and coercive field—remained unchanged.

  5. Magnetization reversal behavior of SmCo6.6Nb0.4 nanoflakes prepared by surfactant-assisted ball milling

    NASA Astrophysics Data System (ADS)

    Li, Y. Q.; Yue, M.; Wu, Q.; Liu, W. Q.; Zhang, D. T.; Lu, Q. M.

    2016-05-01

    In this paper, the recoil loops of SmCo6.6Nb0.4 nanoflakes prepared by the surfactant-assisted high energy ball milling (SA-HEBM) were systematically studied. The recoil loop openness was observed in both the aligned and non-aligned samples. Reversible and irreversible portions of the demagnetization process derived from the recoil loop were also investigated. For both the aligned and non-aligned samples, reversible portion (▵mrev) is too small to determine the coercivity. Irreversible portion (▵mirrev) shows similar tendency, i.e. increasing slowly at low reverse field and then growing up rapidly after a critical field (nucleation field Hno). The demagnetization process can be described as following: the reversible demagnetization is dominant when the applied reverse field is lower than 8 kOe, under which the irreversible nucleation also occurs. The reverse domain walls are pinned by the grain boundaries until the reverse field is larger than 8 kOe. With increasing field, the pinning effects are weakened and the rapid reversible demagnetization starts. Finally, the demagnetization process is accomplished. The values of ΔM in the Henkel plots are totally opposite for the aligned and non-aligned SmCo6.6Nb0.4 nanoflakes.

  6. Magnetic properties and coercivity mechanism of Sm1-xPrxCo5 (x=0-0.6) nanoflakes prepared by surfactant-assisted ball milling

    NASA Astrophysics Data System (ADS)

    Xu, M. L.; Yue, M.; Wu, Q.; Li, Y. Q.; Lu, Q. M.

    2016-05-01

    Sm1-xPrxCo5 (x=0-0.6) nanoflakes with CaCu5 structure were successfully prepared by surfactant-assisted high-energy ball milling (SAHEBM). The crystal structure and magnetic properties of Sm1-xPrxCo5 (x=0-0.6) nanoflakes were studied by X-ray diffraction and vibrating sample magnetometer. Effects of Pr addition on the structure, magnetic properties and coercivity mechanism of Sm1-xPrxCo5 nanoflakes were systematically investigated. XRD results show that all the nanoflakes have a hexagonal CaCu5-type (Sm, Pr)1Co5 main phase and the (Sm, Pr)2Co7 impurity phase, and all of the samples exhibit a strong (00l) texture after magnetic alignment. As the Pr content increases, remanence firstly increases, then slightly reduced, while anisotropy field (HA) and Hci of decrease monotonically. Maximum energy product [(BH)max] of the flakes increases first, peaks at 24.4 MGOe with Pr content of x = 0.4, then drops again. Magnetization behavior analysis indicate that the coercivity mechanism is mainly controlled by inhomogeneous domain wall pinning, and the pinning strength weakens with the increased Pr content, suggesting the great influence of HA on the coercivity of flakes.

  7. Impact of initial catalyst form on the 3D structure and performance of ball-milled Ni-catalyzed MgH2 for hydrogen storage

    DOE PAGES

    House, Stephen D.; Vajo, John J.; Ren, Chai; ...

    2017-02-24

    Although it has been shown that the hydrogen storage kinetics of metal hydrides can be significantly improved by the addition of transition metal-based catalysts, relatively little attention has been paid to the impact that the form in which these catalysts are introduced during synthesis has on the resulting structure and how this alters performance. Two mixtures of MgH2 doped with Ni were prepared via high-energy ball-milling under identical conditions, one using a pure Ni nanopowder catalyst and the other using anhydrous NiCl2. The resulting Ni catalyst particles of the NiCl2-doped material were 10-100 times smaller, as well as more uniformmore » in size and shape. Electron tomography revealed that the additive form also altered its incorporation and 3D spatial distribution, with Ni particles limited to the outer surface in the NiCl2-doped case. The significantly lower desorption performance measured in the NiCl2-doped material is attributed to regions of MgCl2 acting as barriers between the MgH2 and Ni, hindering the ability of the latter to effectively catalyze the reactions. Finally, this work demonstrates the hazards in assuming different catalyst forms produce similar final structures and highlights the potential of catalyst form as a synthesis tool for optimizing the material structure and performance.« less

  8. Influence of ball milling and annealing conditions on the properties of L1{sub 0} FePt nanoparticles fabricated by a new green chemical synthesis method

    SciTech Connect

    Hu, X. C.; Capobianchi, A.; Gallagher, R.; Hadjipanayis, G. C.

    2014-05-07

    In this work, a new green chemical strategy for the synthesis of L1{sub 0} FePt alloy nanoparticles is reported. The precursor is a polycrystalline molecular complex (Fe(H{sub 2}O){sub 6}PtCl{sub 6}), in which Fe and Pt atoms are arranged on alternating planes and milled with NaCl to form nanocrystals. Then the mixture was annealed under reducing atmosphere (5% H{sub 2} and 95% Ar) at temperatures varying from 350 °C to 500 °C for 2 h with a heating rate of 5 °C/min. After the reduction, the mixture was washed with water to remove the NaCl and L1{sub 0} FePt nanoparticles were obtained. The X-Ray Diffraction pattern showed the presence of the characteristic peaks of the fct phase of FePt nanoparticles. Influence of precursor/NaCl ratio and ball milling time on particle size was investigated. Transmission electron microscopy images revealed that smaller precursor/NaCl ratio (10 mg/20 g) and longer milling time (15 h) lead to smaller particle size and narrower size distribution. Milling time does not influence the coercivity much but the decrease of the amount of precursor leads to a decrease of coercivity from 10.8 kOe to 4.8 kOe.

  9. Facile solid state ball milling as a green strategy to prepare 2-(2,4-dichlorophenoxy)-N‧-(2-hydroxybenzylidene)acetohydrazide complexes

    NASA Astrophysics Data System (ADS)

    Fekri, Ahmed; Zaky, Rania

    2014-11-01

    2-(2,4-Dichlorophenoxy)-N‧-(2-hydroxybenzylidene)acetohydrazide (H2L) complexes were prepared by ball milling involving the reaction of ligand with Ni(II), Co(II), Cu(II) and VO(II) salts (mechanochemical syntheses). The compounds were elucidated by elemental analysis, spectroscopy (1H NMR, IR, UV-visible, MS spectra), and physical measurements (magnetic susceptibility and molar conductance). IR spectra suggested that the H2L behaved as a monodentate and/or bidentate ligand coordinating via azomethine nitrogen and/or deprotonated enolized carbonyl oxygen. The electronic spectra of the complexes and their magnetic moments provided information about geometries. The antimicrobial activities of the ligand and its complexes were studied against gram positive bacteria; Staphylococcus aureus, gram-negative bacteria; Escherichia coli and pathogenic fungi; Candida albicans by using minimum inhibition concentrations method (MIC). Also, the antioxidant (ABTS-derived free radical method) and cytotoxic (in vitro Ehrlich Ascites) activities of the isolated compounds were evaluated.

  10. Performance enhancement of NdFeB nanoflakes prepared by surfactant-assisted ball milling at low temperature by using different surfactants

    NASA Astrophysics Data System (ADS)

    An, Xiaoxin; Jin, Kunpeng; Wang, Fang; Fang, Qiuli; Du, Juan; Xia, Weixing; Yan, Aru; Liu, J. Ping; Zhang, Jian

    2017-02-01

    Hard magnetic NdFeB submicron and nanoflakes were successfully prepared by surfactant-assisted ball milling at room temperature (SABMRT) and low temperature (SABMLT) by using oleic acid (OA), oleylamine (OLA) and trioctylamine (TOA) as surfactant, respectively. Among the surfactants used, OA and OLA have similar effects on the morphology of the NdFeB nanoflakes milled at both room and low temperature. In the case of TOA, irregular micron-sized particles and submirco/nanoflakes were obtained for the NdFeB powders prepared by SABMRT and SABMLT, respectively. Samples prepared by SABMLT show better crystallinity and better degree of grain alignment than that prepared by SABMRT with the same surfactant. Comparing with the samples milled at RT, higher coercivity and larger remanence ratio were achieved in the NdFeB samples prepared at LT. The amounts of residual surfactants in final NdFeB powders were also calculated, which reveals that the final NdFeB powders milled at LT possess lower amount of residual surfactants than those milled at RT. It was found that lowering milling temperature of SABM would be a promising way for fabricating permanent magnetic materials with better hard magnetic properties.

  11. Effects of zero-valent metals together with quartz sand on the mechanochemical destruction of dechlorane plus coground in a planetary ball mill.

    PubMed

    Wang, Haizhu; Huang, Jun; Zhang, Kunlun; Yu, Yunfei; Liu, Kai; Yu, Gang; Deng, Shubo; Wang, Bin

    2014-01-15

    Mechanochemical destruction by grinding with additives in high energy ball milling has been identified as a good alternative to traditional incineration for the disposal of wastes containing halogenated organic pollutants. Despite CaO normally used as an additive, recently Fe+SiO2 has been used to replace CaO for a faster destruction. In the present study, zero-valent metals (Al, Zn, besides Fe) together with SiO2 were investigated for their efficiencies of prompting the destruction of dechlorane plus (DP). Aluminum was found of be the best with a destruction percentage of nearly 99% for either syn- or anti-DP after 2.5h milling. In comparison, only 88/85% and 37/32% of syn-/anti-DP were destroyed when using zinc and iron after the same time, respectively. The detected water soluble chloride was lower than the stoichiometric amount containing in the original DP samples, due to the Si-Cl bond formed during the process. The potential fate of C and Cl present in DP is in the form of inorganic carbon, inorganic Cl and formation of Si-Cl bonds, respectively. The results suggested that Al+SiO2 is promising in the mechanochemical destruction of chlorinated organic pollutants like DP. Copyright © 2013 Elsevier B.V. All rights reserved.

  12. The grinding behavior of ground copper powder for Cu/CNT nanocomposite fabrication by using the dry grinding process with a high-speed planetary ball mill

    NASA Astrophysics Data System (ADS)

    Choi, Heekyu; Bor, Amgalan; Sakuragi, Shiori; Lee, Jehyun; Lim, Hyung-Tae

    2016-01-01

    The behavior of ground copper powder for copper-carbon nanotube (copper-CNT) nanocomposite fabrication during high-speed planetary ball milling was investigated because the study of the behavior characteristics of copper powder has recently gained scientific interest. Also, studies of Cu/CNT composites have widely been done due to their useful applications to enhanced, advanced nano materials and components, which would significantly improve the properties of new mechatronics-integrated materials and components. This study varied experimental conditions such as the rotation speed and the grinding time with and without CNTs, and the particle size distribution, median diameter, crystal structure and size, and particle morphology were monitored for a given grinding time. We observed that pure copper powders agglomerated and that the morphology changed with changing rotation speed. The particle agglomerations were observed with maximum experiment conditions (700 rpm, 60 min) in this study of the grinding process for mechanical alloys in the case of pure copper powders because the grinding behavior of Cu/CNT agglomerations was affected by the addition of CNTs. Indeed, the powder morphology and the crystal size of the composite powder could be changed by increasing the grinding time and the rotation speed.

  13. Nanocomposite Formation in Zr-Al-Cu-Ni-Fe Amorphous Alloys by Mechanically Assisted Nitriding

    NASA Astrophysics Data System (ADS)

    Bab, M. A.; Damonte, L. C.; Mendoza-Zélis, L. A.

    2005-04-01

    Zr-Al-Cu-Ni-Fe belongs to the best glass forming systems known. These glasses present a high thermal stability and are suitable as precursor material for nanocomposites containing a variety of particles. At this respect, the presence of a second phase embedded in the amorphous matrix improves their mechanical properties. Ball milling has already demonstrated to be a valuable processing route for producing amorphous matrix nanocomposites, allowing by passing most of the limitations inherent to the casting techniques. In this work we present results on the formation, structure and thermal stability of nanocrystalline nitride particles dispersed in a Zr-Cu-Al-Ni-Fe amorphous matrix. The nitride particles were obtained by high-energy ball milling of Zr64Al7Cu17Ni10Fe2 amorphous ribbons in nitrogen atmosphere. The resulting nanocomposite structure was studied by Mössbauer spectroscopy and x-ray diffraction. Their thermal behavior was analyzed by differential scanning calorimetry, showing an increase in the thermal stability of the amorphous matrix by the composite formation.

  14. Ball-milled nano-colloids of rare-earth compounds as liquid gain media for capillary optical amplifiers and lasers

    NASA Astrophysics Data System (ADS)

    Patel, Darayas; Blockmon, Avery; Ochieng, Vanesa; Lewis, Ashley; Wright, Donald M.; Lewis, Danielle; Valentine, Rueben; Valentine, Maucus; Wesley, Dennis; Sarkisov, Sergey S.; Darwish, Abdalla M.; Sarkisov, Avedik S.

    2017-02-01

    Nano-colloids and nano-crystals doped with ions of rare-earth elements have recently attracted a lot of attention in the scientific community due to their potential applications as biomarkers, fluorescent inks, gain media for lasers and optical amplifiers. Many rare-earth doped materials of different compositions, shapes and size distribution have been prepared by different synthetic methods, such as chemical vapor deposition, sol-gel process, micro-emulsion techniques, gas phase condensation methods, hydrothermal methods and laser ablation. In this paper micro-crystalline powder of the rare-earthdoped compound NaYF4:Yb3+, Er3+ was synthesized using a simple wet process followed by baking in open air. Under 980 nm diode laser excitation strong fluorescence in the 100 nm band around 1531-nm peak was observed from the synthesized micro-powder. The micro-powder was pulverized using a ball mill and prepared in the form of nano-colloids in different liquids. The particle size of the obtained nano-colloids was measured using an atomic force microscope and a dynamic light scatterometer. The size of the nano-particles was close to 100-nm. The nano-colloids were utilized as a filling media in capillary optical amplifiers and lasers. The gain of a 7-cm-long capillary optical amplifier (150-micron inner diameter) was as high as 6 dB at 200 mW pump power. The synthesized nano-colloids and the active optical components using them can be potentially used in optical communication, signal processing, optical computing, and other applications.

  15. Effect of Gd-substitution on the ferroelectric and magnetic properties of BiFeO3 processed by high-energy ball milling

    NASA Astrophysics Data System (ADS)

    Sharma, Shiwani; Mishra, Alok; Saravanan, P.; Pandey, O. P.; Sharma, Puneet

    2016-11-01

    Multiferroic BiFeO3 was synthesized by means of high-energy ball milling (HEBM) followed by thermal annealing at various temperatures and the effect of Gd3+ substitution (x=0.0-0.20) at Bi3+ site was investigated in this study. It is found that the Gd-substitution tends to decrease the impurity phases and the crystallization of single phase BiFeO3 is observed at x=0.1. Scanning electron micrograph of Bi1-xGdxFeO3 sintered sample indicated a decrease in particle size and change in shape with increasing x. For all the studied samples, the measured dielectric constant values tend to increase from 110 (x=0.0) to 250 (x=0.10). The dielectric loss is found to be more for the pure BiFeO3 as compared to the Bi1-xGdxFeO3. Ferroelectric loops show a maximum polarization of 1.63 μC/cm2 for the Bi0.9Gd0.1FeO3. Magnetization (M) versus magnetic field (H) hysteresis loops at 300 K BiFeO3 and Bi0.9Gd0.1FeO3 demonstrated non-saturated loops, suggesting the antiferromagnetic nature of the samples. The M-H behavior of the Bi1-xGdxFeO3 at 300 K shows the antiferromagnetic nature of the samples. The estimated magnetization value at 10 kOe for the Bi0.9Gd0.1FeO3 sample (0.23 emu/g) is found to be higher than that of the pure BiFeO3 (0.037 emu/g).

  16. Enhanced magnetic properties of NiO powders by the mechanical activation of aluminothermic reduction of NiO prepared by a ball milling process

    NASA Astrophysics Data System (ADS)

    Padhan, Aneeta Manjari; Ravikumar, P.; Saravanan, P.; Alagarsamy, Perumal

    2016-11-01

    We report the effect of mechanical activation on NiO-Al (x wt%) reduction reaction and resulting structural and magnetic properties by carrying out high-energy planetary ball milling. The pure NiO (un-milled) and milled NiO-Al (x≤2.5) powders exhibit face centered cubic structure, but the antiferromagnetic nature of pure NiO powder shows significant room temperature ferromagnetism with moderate moment and coercivity after milling due to non-stoichiometry in NiO caused by the defects, size reduction and oxidation of Ni. On the other hand, the addition of Al between 2.5 and 10% in NiO forms solid solution of NiO-Al with considerable reduction in the moment due to the atomic disorder. With increasing Al above 10%, NiO reduction reaction progresses gradually and as a result, the average magnetization increases from 0.57 to 4.3 emu/g with increasing Al up to 25%. A maximum of 91% reduction was observed for NiO-Al (40%) powders in 30 h of milling with a large increase in magnetization (~24 emu/g) along with the development of α-Al2O3. Thermomagnetization data reveal the presence of mixed magnetic phases in milled NiO powders and the component of induced ferromagnetic phase fades out with increasing Al due to the formation of Ni from the NiO-Al reduction reaction. The changes in the structural and magnetic properties are discussed on the basis of mechanical activation on the reduction of NiO by Al. The controlled reduction reaction with different Al content in NiO-Al is encouraging for the applications in catalysis and process of ore reduction.

  17. [Formula: see text]-mediated amination/cyclization of ketones with 2-aminopyridines under high-speed ball milling: solvent- and metal-free synthesis of 2,3-substituted imidazo[1,2-a]pyridines and zolimidine.

    PubMed

    Wang, Fang-Jian; Xu, Hui; Xin, Ming; Zhang, Ze

    2016-08-01

    Under solvent-free high-speed ball milling, an I[Formula: see text]-promoted condensation/cyclization of easily available methyl ketones or 1,3-dicarbonyl compounds with 2-aminopyridines has been developed, which allows the quick assembly of 2,3-substituted imidazo[1,2-a]pyridines (IPs) with broad molecular diversity, including the antiulcer drug zolimidine. The advantages of high yields, good functional group compatibility, short reaction time (within 90 min), free use of heating, solvent and metal, employment of cheap starting materials, and simple work-up procedure make this protocol a very efficient alternative to traditional synthesis of IPs.

  18. Microstructure-Property Correlation in Magnesium-based Hydrogen Storage Systems: The Case for Ball-milled Magnesium Hydride Powder and Magnesium-based Multilayered Composites

    NASA Astrophysics Data System (ADS)

    Danaie, Mohsen

    The main focus of this thesis is the characterization of defects and microstructure in high-energy ball milled magnesium hydride powder and magnesium-based multilayered composites. Enhancement in kinetics of hydrogen cycling in magnesium can be achieved by applying severe plastic deformation. A literature survey reveals that, due to extreme instability of alpha-MgH 2 in transmission electron microscope (TEM), the physical parameters that researchers have studied are limited to particle size and grain size. By utilizing a cryogenic TEM sample holder, we extended the stability time of the hydride phase during TEM characterization. Milling for only 30 minutes resulted in a significant enhancement in desorption kinetics. A subsequent annealing cycle under pressurized hydrogen reverted the kinetics to its initial sluggish state. Cryo-TEM analysis of the milled hydride revealed that mechanical milling induces deformation twinning in the hydride microstructure. Milling did not alter the thermodynamics of desorption. Twins can enhance the kinetics by acting as preferential locations for the heterogeneous nucleation of metallic magnesium. We also looked at the phase transformation characteristics of desorption in MgH2. By using energy-filtered TEM, we investigated the morphology of the phases in a partially desorbed state. Our observations prove that desorption phase transformation in MgH2 is of "nucleation and growth" type, with a substantial energy barrier for nucleation. This is contrary to the generally assumed "core-shell" structure in most of the simulation models for this system. We also tested the hydrogen storage cycling behavior of bulk centimeter-scale Mg-Ti and Mg-SS multilayer composites synthesized by accumulative roll-bonding. Addition of either phase (Ti or SS) allows the reversible hydrogen sorption at 350°C, whereas identically roll-bonded pure magnesium cannot be absorbed. In the composites the first cycle of absorption (also called "activation

  19. Solution-state 2D NMR of ball-milled plant cell wall gels in DMSO-d6/pyridine-d5†

    PubMed Central

    Ralph, John

    2014-01-01

    NMR fingerprinting of the components of finely divided plant cell walls swelled in DMSO has been recently described. Cell wall gels, produced directly in the NMR tube with perdeutero-dimethylsulfoxide, allowed the acquisition of well resolved/dispersed 2D 13C–1H correlated solution-state NMR spectra of the entire array of wall polymers, without the need for component fractionation. That is, without actual solubilization, and without apparent structural modification beyond that inflicted by the ball milling and ultrasonication steps, satisfactorily interpretable spectra can be acquired that reveal compositional and structural details regarding the polysaccharide and lignin components in the wall. Here, the profiling method has been improved by using a mixture of perdeuterated DMSO and pyridine (4:1, v/v). Adding pyridine provided not only easier sample handling because of the better mobility compared to the DMSO-d6-only system but also considerably elevated intensities and improved resolution of the NMR spectra due to the enhanced swelling of the cell walls. This modification therefore provides a more rapid method for comparative structural evaluation of plant cell walls than is currently available. We examined loblolly pine (Pinus taeda, a gymnosperm), aspen (Populus tremuloides, an angiosperm), kenaf (Hibiscus cannabinus, an herbaceous plant), and corn (Zea mays L., a grass, i.e., from the Poaceae family). In principle, lignin composition (notably, the syringyl : guaiacyl : p-hydroxyphenyl ratio) can be quantified without the need for lignin isolation. Correlations for p-coumarate units in the corn sample are readily seen, and a variety of the ferulate correlations are also well resolved; ferulates are important components responsible for cell wall cross-linking in grasses. Polysaccharide anomeric correlations were tentatively assigned for each plant sample based on standard samples and various literature data. With the new potential for chemometric analysis

  20. Synthesis, structural and hydrogenation properties of Mg-rich MgH2-TiH2 nanocomposites prepared by reactive ball milling under hydrogen gas.

    PubMed

    Cuevas, Fermin; Korablov, Dmytro; Latroche, Michel

    2012-01-21

    MgH(2)-TiH(2) nanocomposites have been obtained by reactive ball milling of elemental powders under 8 MPa of hydrogen pressure. The composites consist of a mixture of β-rutile MgH(2), γ-orthorhombic high pressure MgH(2) and ε-tetragonal TiH(2) phases with nanosized crystallites ranging from 4 to 12 nm. In situ hydrogen absorption curves on milling reveal that nanocomposite formation occurs in less than 50 min through the consecutive synthesis of the TiH(2) and MgH(2) phases. The abrasive and catalytic properties of TiH(2) speed up the formation of the MgH(2) phase. Thermodynamic, kinetic and cycling hydrogenation properties have been determined for the 0.7MgH(2)-0.3TiH(2) composite and compared to nanometric MgH(2). Only the MgH(2) phase desorbs hydrogen reversibly at moderate temperature (523 to 598 K) and pressure (10(-3) to 1 MPa). The presence of TiH(2) does not modify the thermodynamic properties of the Mg/MgH(2) system. However, the MgH(2)-TiH(2) nanocomposite exhibits outstanding kinetic properties and cycling stability. At 573 K, H-sorption takes place in less than 100 s. This is 20 times faster than for a pure nanometric MgH(2) powder. We demonstrate that the TiH(2) phase inhibits grain coarsening of Mg, which allows extended nucleation of the MgH(2) phase in Mg nanoparticles before a continuous and blocking MgH(2) hydride layer is formed. The low crystallinity of the TiH(2) phase and its hydrogenation properties are also compatible with a gateway mechanism for hydrogen transfer from the gas phase to Mg. Mg-rich MgH(2)-TiH(2) nanocomposites are an excellent media for hydrogen storage at moderate temperatures.

  1. Effects of processing parameters on the synthesis of (K0.5Na0.5)NbO3 nanopowders by reactive high-energy ball milling method.

    PubMed

    Nguyen, Duc Van

    2014-01-01

    The effects of ball milling parameters, namely, the ball-to-powder mass ratio and milling speed, on the synthesis of (K0.5Na0.5)NbO3 nanopowders by high-energy ball milling method from a stoichiometric mixture containing Na2CO3, K2CO3, and Nb2O5 were investigated in this paper. The results indicated that the single crystalline phase of (K0.5Na0.5)NbO3 was received in as-milled samples synthesized using optimized ball-to-powder mass ratio of 35 : 1 and at a milling speed of 600 rpm for 5 h. In the optimized as-milled samples, no remaining alkali carbonates that can provide the volatilizable potassium-containing species were found and (K0.5Na0.5)NbO3 nanopowders were readily obtained via the formation of an intermediate carbonato complex. This complex was mostly transformed into (K0.5Na0.5)NbO3 at temperature as low as 350°C and its existence was no longer detected at spectroscopic level when calcination temperature crossed over 700°C.

  2. Effects of Processing Parameters on the Synthesis of (K0.5Na0.5)NbO3 Nanopowders by Reactive High-Energy Ball Milling Method

    PubMed Central

    Duc Van, Nguyen

    2014-01-01

    The effects of ball milling parameters, namely, the ball-to-powder mass ratio and milling speed, on the synthesis of (K0.5Na0.5)NbO3 nanopowders by high-energy ball milling method from a stoichiometric mixture containing Na2CO3, K2CO3, and Nb2O5 were investigated in this paper. The results indicated that the single crystalline phase of (K0.5Na0.5)NbO3 was received in as-milled samples synthesized using optimized ball-to-powder mass ratio of 35 : 1 and at a milling speed of 600 rpm for 5 h. In the optimized as-milled samples, no remaining alkali carbonates that can provide the volatilizable potassium-containing species were found and (K0.5Na0.5)NbO3 nanopowders were readily obtained via the formation of an intermediate carbonato complex. This complex was mostly transformed into (K0.5Na0.5)NbO3 at temperature as low as 350°C and its existence was no longer detected at spectroscopic level when calcination temperature crossed over 700°C. PMID:24592146

  3. Deformation-enhanced thermal stability of an amorphous Fe80B20 alloy

    NASA Astrophysics Data System (ADS)

    Fan, G. J.; Quan, M. X.; Hu, Z. Q.

    1996-11-01

    By means of differential scanning calorimeter (DSC) measurements, the thermal stability of an amorphous Fe80B20 alloy after various periods of low-energy ball milling has been studied. The results indicate that the thermal stability of the amorphous Fe80B20 ribbons can be enhanced upon mechanical deformation with a low milling intensity. The crystallization temperature Tp, the crystallization enthalpy ΔH, and the crystallization activation energy Ex increase with milling time. The above observations will be compared with our previous findings that extensive mechanical deformation with a high milling intensity can otherwise induce a structural relaxation in an amorphous Fe80B20 alloy. Based on conventional thermodynamic and kinetic arguments, a reasonable interpretation will be made to explain the enhanced thermal stability of the amorphous Fe80B20 alloy after mechanical deformation.

  4. Solid-state amorphization of rebamipide and investigation on solubility and stability of the amorphous form.

    PubMed

    Xiong, Xinnuo; Xu, Kailin; Li, Shanshan; Tang, Peixiao; Xiao, Ying; Li, Hui

    2017-02-01

    Solid-state amorphization of crystalline rebamipide (RBM) was realized by ball milling and spray drying. The amorphous content of samples milled for various time was quantified using X-ray powder diffraction. Crystalline RBM and three amorphous RBM obtained by milling and spray drying were characterized by morphological analysis, X-ray diffraction, thermal analysis and vibrational spectroscopy. The crystal structure of RBM was first determined by single-crystal X-ray diffraction. In addition, the solubility and dissolution rate of the RBM samples were investigated in different media. Results indicated that the solubility and the dissolution rates of spray-dried RBM-PVP in different media were highly improved compared with crystalline RBM. The physical stabilities of the three amorphous RBM were systematically investigated, and the stability orders under different storage temperatures and levels of relative humidity (RH) were both as follows: spray dried RBM < milled RBM < spray dried RBM-PVP. A direct glass-to-crystal transformation was induced under high RH, and the transformation rate rose with increasing RH. However, amorphous RBM could stay stable at RH levels lower than 57.6% (25 °C).

  5. Characterization of Amorphous and Co-Amorphous Simvastatin Formulations Prepared by Spray Drying.

    PubMed

    Craye, Goedele; Löbmann, Korbinian; Grohganz, Holger; Rades, Thomas; Laitinen, Riikka

    2015-12-03

    In this study, spray drying from aqueous solutions, using the surface-active agent sodium lauryl sulfate (SLS) as a solubilizer, was explored as a production method for co-amorphous simvastatin-lysine (SVS-LYS) at 1:1 molar mixtures, which previously have been observed to form a co-amorphous mixture upon ball milling. In addition, a spray-dried formulation of SVS without LYS was prepared. Energy-dispersive X-ray spectroscopy (EDS) revealed that SLS coated the SVS and SVS-LYS particles upon spray drying. X-ray powder diffraction (XRPD) and differential scanning calorimetry (DSC) showed that in the spray-dried formulations the remaining crystallinity originated from SLS only. The best dissolution properties and a "spring and parachute" effect were found for SVS spray-dried from a 5% SLS solution without LYS. Despite the presence of at least partially crystalline SLS in the mixtures, all the studied formulations were able to significantly extend the stability of amorphous SVS compared to previous co-amorphous formulations of SVS. The best stability (at least 12 months in dry conditions) was observed when SLS was spray-dried with SVS (and LYS). In conclusion, spray drying of SVS and LYS from aqueous surfactant solutions was able to produce formulations with improved physical stability for amorphous SVS.

  6. Inkjet-printed flexible organic thin-film thermoelectric devices based on p- and n-type poly(metal 1,1,2,2-ethenetetrathiolate)s/polymer composites through ball-milling

    PubMed Central

    Jiao, Fei; Di, Chong-an; Sun, Yimeng; Sheng, Peng; Xu, Wei; Zhu, Daoben

    2014-01-01

    In this article, we put forward a simple method for the synthesis of thermoelectric (TE) composite materials. Both n- and p-type composites were obtained by ball-milling the insoluble and infusible metal coordination polymers with other polymer solutions. The particle size, film morphology and composition were characterized by dynamic light scattering, scanning electron microscopy, transmission electron microscopy and energy-dispersive X-ray spectroscopy. The TE properties of the drop-cast composite film were measured at different temperatures. An inkjet-printed flexible device was fabricated and the output voltage and short-circuit current at various hot-side temperatures (Thot) and temperature gradients (ΔT) were tested. The composite material not only highly maintained the TE properties of the pristine material but also greatly improved its processability. This method can be extended to other insoluble and infusible TE materials for solution-processed flexible TE devices. PMID:24615147

  7. C, N co-doped TiO2/TiC0.7N0.3 composite coatings prepared from TiC0.7N0.3 powder using ball milling followed by oxidation

    NASA Astrophysics Data System (ADS)

    Hao, Liang; Wang, Zhenwei; Zheng, Yaoqing; Li, Qianqian; Guan, Sujun; Zhao, Qian; Cheng, Lijun; Lu, Yun; Liu, Jizi

    2017-01-01

    Ball milling followed by heat oxidation was used to prepared C, N co-doped TiO2 coatings on the surfaces of Al2O3 balls from TiC0.7N0.3 powder. The as-prepared coatings were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and ultraviolet-visible spectrophotometer (UV-vis). The results show that continuous TiC0.7N0.3 coatings were formed after ball milling. C, N co-doped TiO2/TiC0.7N0.3 composite coatings were prepared after the direct oxidization of TiC0.7N0.3 coatings in the atmosphere. However, TiO2 was hardly formed in the surface layer of TiC0.7N0.3 coatings within a depth less than 10 nm during the heat oxidation of TiC0.7N0.3 coatings in carbon powder. Meanwhile, the photocatalytic activity evaluation of these coatings was conducted under the irradiation of UV and visible light. All the coatings showed photocatalytic activity in the degradation of MB no matter under the irradiation of UV or visible light. The C, N co-doped TiO2/TiC0.7N0.3 composite coatings showed the most excellent performance. The enhancement under visible light irradiation should attribute to the co-doping of carbon and nitrogen, which enhances the absorption of visible light. The improvement of photocatalytic activity under UV irradiation should attribute to the synergistic effect of C, N co-doping, the formation of rutile-anatase mixed phases and the TiO2/TiC0.7N0.3 composite microstructure.

  8. Effect of sintering in ball-milled K{sub 2}Bi{sub 8}Se{sub 13} thermoelectric nano-composites

    SciTech Connect

    Hatzikraniotis, E.; Ioannou, M.; Chrissafis, K.; Chung, D.Y.; Paraskevopoulos, K.M.; Kyratsi, Th.

    2012-09-15

    K{sub 2}Bi{sub 8}Se{sub 13} has many attractive features for thermoelectric applications. Recently, K{sub 2}Bi{sub 8}Se{sub 13}-based nanocomposite materials, consisting of nano-crystalline, micro-crystalline and amorphous phases, have been fabricated based on powder technology techniques. The Seebeck coefficient has been enhanced while the thermal conductivity has been decreased presenting, thus, interesting behavior. The behavior of the materials under heat treatment conditions is now of interest, as the application of sintering process is necessary for the development of thermoelectric modules. In this work, the crystallization of the K{sub 2}Bi{sub 8}Se{sub 13}-based nano-composites is studied using Differential Scanning Calorimetry. The results show that crystallization follows a multiple-step process with different activation energies. The thermoelectric properties are also discussed in the range that crystallization occurs. - Graphical Abstract: {beta}-K{sub 2}Bi{sub 8}Se{sub 13}-based nanocomposites follow a multiple-step crystallization process. Highlights: Black-Right-Pointing-Pointer K{sub 2}Bi{sub 8}Se{sub 13}-based composites consisting of nanocrystalline and amorphous phases. Black-Right-Pointing-Pointer Sintering results multiple-step crystallization with variable activation energies. Black-Right-Pointing-Pointer Thermoelectric properties follow a step-like behavior during sintering. Black-Right-Pointing-Pointer Properties are attributed to the strain relaxation, nucleation and grain growth.

  9. Influence of polymer content on stabilizing milled amorphous salbutamol sulphate.

    PubMed

    Balani, P N; Wong, S Y; Ng, W K; Widjaja, E; Tan, R B H; Chan, S Y

    2010-05-31

    The study investigates the influence of polyvinyl pyrrolidone (PVP) concentration on stabilizing the amorphous form of salbutamol sulphate (SS) before and after storage under ambient and elevated humidity conditions. Different mass ratios of SS and PVP (0-90wt%) were co-milled using a planetary ball mill. X-ray powder diffraction (XRPD), high sensitivity differential scanning calorimetry (HSDSC), dynamic vapor sorption (DVS), infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and Raman microscopy (RM) were used to analyze the stability of the co-milled mixtures against heat and humidity treatments as well as storage at different humidity conditions. Prior storage, DSC and DVS analyses revealed that re-crystallization of amorphous SS was suppressed above PVP content of 33 wt%. Probable hydrogen bond interaction between SS and PVP was found in FT-IR analysis. XRPD diffractograms and SEM analysis showed stability against re-crystallization was achieved in the co-milled mixtures with a minimum PVP content of 80 wt% after storage. Homogeneous distribution of SS and PVP from RM analysis showed fine clustering of SS and PVP, suggesting the formation of an amorphous dispersion at molecular level. The results provide insights on the application of thermal and humidity treatments, accelerated stability testing and investigations on drug-excipient interactions to predict the minimum ratio of an excipient for stabilizing the amorphous state of a milled API. Copyright (c) 2010 Elsevier B.V. All rights reserved.

  10. Preparation of Mo-Re-C samples containing Mo7Re13C with the β-Mn-type structure by solid state reaction of planetary-ball-milled powder mixtures of Mo, Re and C, and their crystal structures and superconductivity

    NASA Astrophysics Data System (ADS)

    Oh-ishi, Katsuyoshi; Nagumo, Kenta; Tateishi, Kazuya; Takafumi, Ohnishi; Yoshikane, Kenta; Sugiyama, Machiko; Oka, Kengo; Kobayashi, Ryota

    2017-01-01

    Mo-Re-C compounds containing Mo7Re13C with the β-Mn structure were synthesized with high-melting-temperature metals Mo, Re, and C powders using a conventional solid state method with a planetary ball milling machine instead of the arc melting method. Use of the ball milling machine was necessary to obtain Mo7Re13C with the β-Mn structure using the solid state method. Almost single-phase Mo7Re13C with a trace of impurity were obtained using the synthesis method. By XRF and lattice parameter measurements on the samples, Fe element existed in the compound synthesized using the planetary ball milling machine with a pot and balls made of steel, though Fe element was not detected in the compound synthesized using a pot and balls made of tungsten carbide. The former compound containg the Fe atom did not show superconductivity but the latter compound without the Fe atom showed superconductivity at 6.1 K.

  11. Magnetic properties and coercivity mechanism of Sm{sub 1-x}Pr{sub x}Co{sub 5} (x=0-0.6) nanoflakes prepared by surfactant-assisted ball milling

    SciTech Connect

    Xu, M. L.; Yue, M. Wu, Q.; Li, Y. Q.; Lu, Q. M.

    2016-05-15

    Sm{sub 1-x}Pr{sub x}Co{sub 5} (x=0-0.6) nanoflakes with CaCu{sub 5} structure were successfully prepared by surfactant-assisted high-energy ball milling (SAHEBM). The crystal structure and magnetic properties of Sm{sub 1-x}Pr{sub x}Co{sub 5} (x=0-0.6) nanoflakes were studied by X-ray diffraction and vibrating sample magnetometer. Effects of Pr addition on the structure, magnetic properties and coercivity mechanism of Sm{sub 1-x}Pr{sub x}Co{sub 5} nanoflakes were systematically investigated. XRD results show that all the nanoflakes have a hexagonal CaCu{sub 5}-type (Sm, Pr){sub 1}Co{sub 5} main phase and the (Sm, Pr){sub 2}Co{sub 7} impurity phase, and all of the samples exhibit a strong (00l) texture after magnetic alignment. As the Pr content increases, remanence firstly increases, then slightly reduced, while anisotropy field (H{sub A}) and H{sub ci} of decrease monotonically. Maximum energy product [(BH){sub max}] of the flakes increases first, peaks at 24.4 MGOe with Pr content of x = 0.4, then drops again. Magnetization behavior analysis indicate that the coercivity mechanism is mainly controlled by inhomogeneous domain wall pinning, and the pinning strength weakens with the increased Pr content, suggesting the great influence of H{sub A} on the coercivity of flakes.

  12. Mössbauer spectroscopy study of the high energy ball milling (HEBM) synthesis & kinetics of CoFe2O4 from Co(OH)2 and α-Fe2O3

    NASA Astrophysics Data System (ADS)

    Uwakweh, Oswald N. C.; Pérez Moyet, Richard

    2010-03-01

    Room temperature mechanochemical synthesis of single phase nanosized particles of CoFe2O4 by HEBM of stoichiometric mixtures of Co(OH)2 and α-Fe2O3 under wet acetone was achieved after 25 hours of continuous ball milling. The particle size and lattice constant were 98.13 nm, and 8.398 Å after 10 hours, while 31.96 nm and 8.343 Å after 25 hours. The coercivity (25 hours state) was 12.78 mT with saturation and remanent magnetizations of 27.52 Am2/kg and 3.94 Am2/kg respectively due to small amount of a magnetic phase. Mössbauer spectroscopy measurements showed very limited reaction in 5 hours, with the single phase forming directly to superparamagnetic particles. The quadrupole splitting of the doublets was in the range of 0.24-1.14 mm/s, with corresponding isomer shift range of 0.80 -0.67 mm/s. The DSC measurements of the single phase material showed that it was metastable with characteristic stages whose activation energies were determined by the modified Kissinger kinetic analyses to be in the range of 3.51 kJ/mol to 11.89 kJ/mol.

  13. An x-ray photoemission electron microscopy study of the formation of Ti-Al phases in 4 mol% TiCl3 catalyzed NaAlH4 during high energy ball milling

    NASA Astrophysics Data System (ADS)

    Dobbins, Tabbetha; Abrecht, Mike; Uprety, Youaraj; Moore, Kristan

    2009-05-01

    This study reports reaction pathways to form TiAlx metallic complexes during the high energy ball milling of 4 mol% TiCl3 with NaAlH4 powders determined using local structure analysis of Tix+ and Alx+ species. Using x-ray photoemission electron microscopy (XPEEM) and x-ray diffraction (XRD), the oxidation state of Alx+ and Tix+ and the crystalline compounds existing in equilibrium with NaAlH4 were tracked for samples milled for times of 0 (i.e. mixing), 5, and 25 min. XPEEM analysis of the Al K edge after 5 min of milling reveals that Al remains in the 3+ oxidation state (i.e. in NaAlH4) around Ti0-rich regions of the sample. After 25 min of high energy milling, Ti0 has reacted with Al3+ (in nearby NaAlH4) to form TiAlx complexes. This study reports the pathway for TiAlx complex formation during milling of 4 mol% TiCl3 catalyzed NaAlH4 to be as follows: (1) Ti3+ reduces to Ti0 (with Al3+ near Ti0 regions) and (2) Ti0 reacts with Al3+ in NaAlH4 to form TiAlx complexes.

  14. Electrical and dielectric properties of Na1/2La1/2Cu3Ti4O12 ceramics prepared by high energy ball-milling and conventional sintering

    NASA Astrophysics Data System (ADS)

    Mahfoz Kotb, H.; Ahmad, Mohamad M.

    2016-12-01

    We report on the measurements of the electrical and dielectric properties of Na1/2La1/2Cu3Ti4O12 (NLCTO) ceramics prepared by high energy ball-milling and conventional sintering without any calcination steps. The x-ray powder diffraction analysis shows that pure perovskite-like CCTO phase is obtained after sintering at 1025 °C-1075 °C. Higher sintering temperatures result in multi-phase ceramics due to thermal decomposition. Scanning electron microscope observations reveal that the grain size is in a range of ˜3 μm-5μm for these ceramics. Impedance spectroscopy measurements performed in a wide frequency range (1 Hz-10 MHz) and at various temperatures (120 K-470 K) are used to study the dielectric and electrical properties of NLCTO ceramics. A good compromise between high ɛ‧ (5.7 × 103 and 4.1 × 103 at 1.1 kHz and 96 kHz, respectively) and low tan δ (0.161 and 0.126 at 1.1 kHz and 96 kHz, respectively) is obtained for the ceramic sintered at 1050 °C. The observed high dielectric constant behavior is explained in terms of the internal barrier layer capacitance effect.

  15. Coexistence of short- and long-range ferromagnetic order in nanocrystalline Fe2Mn1-xCuxAl (x=0.0, 0.1 and 0.3) synthesized by high-energy ball milling

    NASA Astrophysics Data System (ADS)

    Thanh, Tran Dang; Nanto, Dwi; Tuyen, Ngo Thi Uyen; Nan, Wen-Zhe; Yu, YiKyung; Tartakovsky, Daniel M.; Yu, S. C.

    2015-11-01

    In this work, we prepared nanocrystalline Fe2Mn1-xCuxAl (x=0.0, 0.1 and 0.3) powders by the high energy ball milling technique, and then studied their critical properties. Our analysis reveals that the increase of Cu-doping concentration (up to x=0.3) in these powders leads to a gradual increase of the ferromagnetic-paramagnetic transition temperature from 406 to 452 K. The Banerjee criterion suggests that all the samples considered undergo a second-order phase transition. A modified Arrott plot and scaling analysis indicate that the critical exponents (β=0.419 and 0.442, γ=1.082 and 1.116 for x=0.0 and 0.1, respectively) are located in between those expected for the 3D-Heisenberg and the mean-field models; the values of β=0.495 and γ=1.046 for x=0.3 sample are very close to those of the mean-field model. These features reveal the coexistence of the short- and long-range ferromagnetic order in the nanocrystalline Fe2Mn1-xCuxAl powders. Particularly, as the concentration of Cu increases, values of the critical exponent shift towards those of the mean-field model. Such results prove the Cu doping favors establishing a long-range ferromagnetic order.

  16. The influence of amorphization methods on the apparent solubility and dissolution rate of tadalafil.

    PubMed

    Wlodarski, K; Sawicki, W; Paluch, K J; Tajber, L; Grembecka, M; Hawelek, L; Wojnarowska, Z; Grzybowska, K; Talik, E; Paluch, M

    2014-10-01

    This study for the first time investigates the solubility and dissolution rate of amorphous tadalafil (Td)--a poorly water soluble chemical compound which is commonly used for treating the erectile dysfunction. To convert the crystalline form of Td drug to its amorphous counterpart we have employed most of the commercially available amorphization techniques i.e. vitrification, cryogenic grinding, ball milling, spray drying, freeze drying and antisolvent precipitation. Among the mentioned methods only quenched cooling of the molten sample was found to be an inappropriate method of Td amorphization. This is due to the thermal decomposition of Td above 200°C, as proved by the thermogravimetric analysis (TGA). Disordered character of all examined samples was confirmed using differential scanning calorimetry (DSC) and X-ray powder diffraction (PXRD). In the case of most amorphous powders, the largest 3-fold increase of apparent solubility was observed after 5 min, indicating their fast recrystallization in water. On the other hand, the partially amorphous precipitate of Td and hypromellose enhanced the solubility of Td approximately 14 times, as compared with a crystalline substance, which remained constant for half an hour. Finally, disk intrinsic dissolution rate (DIDR) of amorphous forms of Td was also examined. Copyright © 2014 Elsevier B.V. All rights reserved.

  17. Synthesis and analysis of nanocrystalline β1-Cu3Al and β2-NiAl intermetallic-reinforced aluminum matrix composite by high energy ball milling

    NASA Astrophysics Data System (ADS)

    Nguyen, Hong-Hai; Nguyen, Minh-Thuyet; Kim, Won Joo; Kim, Jin-Chun

    2017-01-01

    Nanocrystalline β1-Cu3Al and β2-NiAl intermetallic compounds were in-situ reinforced in the aluminum matrix with the atomic composition of Al67Cu20Ni13 by the mechanical alloying of elemental powders. Both β1-Cu3Al, β2-NiAl phases that can be only co-synthesized in Cu base alloys have been obtained after 15h milling in this study. The phase evolution during milling process was investigated by X-ray diffraction. The β1-Cu3Al, β2-NiAl phases were metastable with further milling time up to 40 h. Specially, unreacted Al matrix has been totally transformed to amorphous state in the final powder. A remarkable crystalline size of 6.5 nm was reached after 15 h milling time. Thermal stability of the milled powder was also studied by differential thermal analysis. It is shown that β1-Cu3Al, β2-NiAl phases were stable up to higher than 550 °C. Moreover, the inter-diffusion between Al matrix and Cu3Al within the temperature range of 620-740 °C led to the formation of superstructure ζ1-Al3Cu4 phase.

  18. Connecting defects and amorphization in UiO-66 and MIL-140 metal-organic frameworks: a combined experimental and computational study

    NASA Astrophysics Data System (ADS)

    Bennett, Thomas D.; Todorova, Tanya K.; Baxter, Emma F.; Reid, David G.; Gervais, Christel; Bueken, Bart; Van de Voorde, B.; De Vos, Dirk; Keen, David A.; Mellot-Draznieks, Caroline

    The mechanism and products of the structural collapse of the metal-organic frameworks (MOFs) UiO-66, MIL-140B and MIL-140C upon ball-milling are investigated through solid state 13C NMR and pair distribution function (PDF) studies, finding amorphization to proceed by the breaking of a fraction of metal-ligand bonding in each case. The amorphous products contain inorganic-organic bonding motifs reminiscent of the crystalline phases. Whilst the inorganic Zr6O4(OH)4 clusters of UiO-66 remain intact upon structural collapse, the ZrO backbone of the MIL-140 frameworks undergoes substantial distortion. Density functional theory calculations have been performed to investigate defective models of MIL-140B and show, through comparison of calculated and experimental 13C NMR spectra, that amorphization and defects in the materials are linked.

  19. Investigation of preparation methods on surface/bulk structural relaxation and glass fragility of amorphous solid dispersions.

    PubMed

    Ke, Peng; Hasegawa, Susumu; Al-Obaidi, Hisham; Buckton, Graham

    2012-01-17

    The objective of this study was to investigate the effect of preparation methods on the surface/bulk molecular mobility and glass fragility of solid dispersions. Solid dispersions containing indomethacin and PVP K30 were chosen as the model system. An inverse gas chromatography method was used to determine the surface structural relaxation of the solid dispersions and these data were compared to those for bulk relaxation obtained by DSC. The values of τ(β) for the surface relaxation were 4.6, 7.1 and 1.8h for melt quenched, ball milled and spray dried solid dispersions respectively, compared to 15.6, 7.9 and 9.8h of the bulk. In all systems, the surface had higher molecular mobility than the bulk. The glass fragility of the solid dispersions was also influenced by the preparation methods with the most fragile system showing the best stability. The zero mobility temperature (T(0)) was used to correlate with the physical stability of the solid dispersions. Despite having similar T(g) (65°C), the T(0) of the melt quenched, ball milled and spray dried samples were 21.6, -4.2 and 16.7°C respectively which correlated well with their physical stability results. Therefore, T(0) appears to be a better indicator than T(g) for predicting stability of amorphous materials.

  20. Hot Melt Extrusion and Spray Drying of Co-amorphous Indomethacin-Arginine With Polymers.

    PubMed

    Lenz, Elisabeth; Löbmann, Korbinian; Rades, Thomas; Knop, Klaus; Kleinebudde, Peter

    2017-01-01

    Co-amorphous drug-amino acid systems have gained growing interest as an alternative to common amorphous formulations which contain polymers as stabilizers. Several preparation methods have recently been investigated, including vibrational ball milling on a laboratory scale or spray drying in a larger scale. In this study, the feasibility of hot melt extrusion for continuous manufacturing of co-amorphous drug-amino acid formulations was examined, challenging the fact that amino acids melt with degradation at high temperatures. Furthermore, the need for an addition of a polymer in this process was evaluated. After a polymer screening via the solvent evaporation method, co-amorphous indomethacin-arginine was prepared by a melting-solvent extrusion process without and with copovidone. The obtained products were characterized with respect to their solid-state properties, non-sink dissolution behavior, and stability. Results were compared to those of spray-dried formulations with the same compositions and to spray-dried indomethacin-copovidone. Overall, stable co-amorphous systems could be prepared by extrusion without or with copovidone, which exhibited comparable molecular interaction properties to the respective spray-dried products, while phase separation was detected by differential scanning calorimetry in several cases. The formulations containing indomethacin in combination with arginine and copovidone showed enhanced dissolution behavior over the formulations with only copovidone or arginine.

  1. Aluminum Matrix Composites Strengthened with CuZrAgAl Amorphous Atomized Powder Particles

    NASA Astrophysics Data System (ADS)

    Dutkiewicz, Jan; Rogal, Łukasz; Wajda, Wojciech; Kukuła-Kurzyniec, Agata; Coddet, Christian; Dembinski, Lucas

    2015-06-01

    The Al-matrix composites were prepared by hot pressing in vacuum of an aluminum powder with 20 and 40 wt.% addition of the amorphous Cu43Zr43Ag7Al7 alloy (numbers indicate at.%) obtained using gas atomization method. The amorphous structure of the powder was confirmed using x-ray diffraction, DSC, and TEM. The average size of mostly spherical particles was 100 μm, so the powder was sieved to obtain maximum size of 60 μm. The composites were prepared using uniaxial cold pressing in vacuum and at a temperature of 400 °C. The composites of hardness from 43 to 53 HV were obtained for both additions of the amorphous phase. They reached compression strength of 150 MPa for 20% of amorphous phase and 250 MPa for the higher content. The modest hardening effect was caused by crack initiation at Al/amorphous interfaces. The amorphous phase was only partially crystallized in the hot-pressed composites, what did not cause hardness decrease. The application of nanocrystalline aluminum powders obtained by high-energy ball milling for the matrix of composites allowed obtaining nanocrystalline aluminum matrix composites of size near 150 nm, strengthened with the amorphous powders, whose compression strength was near 550 MPa for the composite containing 40% of the amorphous phase and slightly lower for the composite containing 20% of the phase. They showed much higher ductility of 23% in comparison with 7% for the composite containing 40% amorphous phase. The distribution of the strengthening phase in the nanocrystalline matrix was not homogeneous; the amorphous particles formed bands, where majority of cracks nucleated during compression test.

  2. M{umlt o}ssbauer investigation of intermixing during ball milling of Fe{sub 0.3}Cr{sub 0.7} and Fe{sub 0.5}W{sub 0.5} powder mixtures

    SciTech Connect

    Le Caeer, G.; Delcroix, P.; Shen, T.D.; Malaman, B.

    1996-11-01

    Intermixing of Fe and T (T=Cr,W) during ball milling of elemental powder mixtures Fe{sub 1{minus}x}T{sub x}, with x=0.70 for T=Cr and x=0.50 for T=W, has been followed by {sup 57}Fe M{umlt o}ssbauer spectroscopy at room temperature (RT) and by magnetization measurements for T=W. The chemical compositions have been chosen to yield final alloys or compounds which are nonmagnetic at RT to better follow the evolution of magnetic phases with milling times. For a long period of milling time t{sub m} before reaching the final stationary state, the hyperfine magnetic field distributions remain stationary in shape for both T=Cr and T=W. Only the relative weight of the magnetic contribution decreases with t{sub m}. For T=W, the average moment of magnetic Fe atoms is further shown to remain constant with t{sub m}. Stationary hyperfine field distribution shapes are found to be similar not only for {ital T}=Cr and W but also for T=Si (x=0.50) while published spectra suggest to add T=Al, Ti, V, Ta, Re to the latter nonexhaustive list. The stationary shape is characterized by a narrow peak located at a field close to the field of alpha iron at RT (330 kG) and by a broad, almost featureless, band from 50-100 kG to 300-320 kG. The broad band represents about 2/3 of the normalized field distribution. We deduce that the interpretation which consists in attributing the x-ray diffraction peaks of Fe-based bcc solid solutions to a single Fe-rich homogeneous solid solution must be done with care for intermediate milling times. We cannot infer from such hyperfine measurements a detailed description of the regions of the powders which are responsible for such magnetic features. We argue however that irregular interfaces between nanometer-sized Fe-rich zones and {ital T}-rich zones may play a role to explain the observed shape of the hyperfine field distributions.

  3. Metal powder reactions in ball milling

    NASA Technical Reports Server (NTRS)

    Arias, A.

    1976-01-01

    On milling chromium powder in three metal chlorides and either chromium or nickel powders in ten organic liquids representative of nine different functional groups, the powders always reacted with the liquids and became contaminated with elements from them. The milled powders had specific surface areas ranging from 0.14 to 37 sq m/g, and the total contamination with elements from the milling liquid ranged from 0.01 to 56 wt%. In most milling runs, compounds resulting from substitution, addition, or elimination reactions formed in or from the milling liquid, and in most runs with organic liquids H2, CH4, and CO2 were generated.

  4. Influence of excipients in comilling on mitigating milling-induced amorphization or structural disorder of crystalline pharmaceutical actives.

    PubMed

    Balani, Prashant N; Ng, Wai Kiong; Tan, Reginald B H; Chan, Sui Yung

    2010-05-01

    The feasibility of using excipients to suppress the amorphization or structural disorder of crystalline salbutamol sulphate (SS) during milling was investigated. SS was subjected to ball-milling in the presence of alpha-lactose monohydrate (LAC), adipic acid (AA), magnesium stearate (MgSt), or polyvinyl pyrrolidone (PVP). X-ray powder diffraction, dynamic vapor sorption (DVS), high sensitivity differential scanning calorimetry (HSDSC) were used to analyze the crystallinity of the milled mixtures. Comilling with crystalline excipients, LAC, AA, and MgSt proved effective in reducing the amorphization of SS. LAC, AA, or MgSt acting as seed crystals to induce recrystallization of amorphous SS formed by milling. During comilling, both SS and LAC turned predominantly amorphous after 45 min but transformed back to a highly crystalline state after 60 min. Amorphous content was below the detection limits of DVS (0.5%) and HSDSC (5%). Comilled and physical mixtures of SS and ALM were stored under normal and elevated humidity conditions. This was found to prevent subsequent changes in crystallinity and morphology of comilled SS:LAC as compared to significant changes in milled SS and physical mixture. These results demonstrate a promising application of comilling with crystalline excipients in mitigating milling induced amorphization of pharmaceutical actives.

  5. Formation of physically stable amorphous phase of ibuprofen by solid state milling with kaolin.

    PubMed

    Mallick, Subrata; Pattnaik, Satyanarayan; Swain, Kalpana; De, Pintu K; Saha, Arindam; Ghoshal, Gaurisankar; Mondal, Arijit

    2008-02-01

    Ibuprofen was milled in the solid state with kaolin (hydrated aluminium silicate) in different ratio to examine the extent of transformation from crystalline to amorphous state. The physical stability of the resultant drug was also investigated. X-ray powder diffractometry (XRD) and birefringence by Scanning Electron Microscopy (SEM) studies indicated almost complete amorphization of the drug on ball milling with kaolin at 1:2 ratio. Fourier transform infrared spectroscopy (FTIR) data showed a reduction in the absorbance of the free and the hydrogen-bonded acid carbonyl peak of carboxylic acid group accompanied by a corresponding increase in the absorbance of the carboxylate peak, indicating an acid-base reaction between the carboxylic acid containing ibuprofen and kaolin on milling. The extent of amorphization and reduction in the carbonyl peak and increase in carboxylate peak was a function of kaolin concentration in the milled powder. On storage of milled powder (at 40 degrees C and 75% RH for 10 weeks), XRD and birefringence of SEM study showed the absence of reversion to the crystalline state and FTIR data revealed continued reduction of carbonyl peak, whereas, ibuprofen converted from its crystalline acid form to amorphous salt form on milling with kaolin. Kaolin-bound state of ibuprofen was physically stable during storage. In-vitro dissolution studies revealed that percent release of ibuprofen from the kaolin co-milled powder is in the order: 1:2>1:1>1:0.5>1:0.1>milled alone ibuprofen>crystalline ibuprofen.

  6. Fabrication of Nd-Fe-B/alpha-Fe nanocomposite magnets by shock compaction and heat treatment of amorphous alloys

    NASA Astrophysics Data System (ADS)

    Wehrenberg, Christopher; Zande, Brian; Sankar, S. G.; Thadhani, Naresh

    2011-06-01

    Bulk nanocomposite magnets based on the Nd-Fe-B system were fabricated using mechanical alloying and shock compaction. A high energy ball mill was used to combine Magnaquench MQA-T type Nd-Fe-B powder with varying amounts of pure Fe powder. The resulting mechanically amorphized powders were shock compacted to near full density. Bulk temperature increase during compaction was suppressed by chilling the target fixture with liquid nitrogen prior to compaction. A range of heat treatments were applied to the recovered samples, and the resulting magnetic properties and crystallization behavior were recorded. The presence of additional iron increases magnetization saturation linearly, but decreases coercivity. The coercivity of the shock consolidated compacts showed an increase to a maximum value upon heat treatment of 550 C.

  7. Preparation of Fe-Ni-Based Metal-Metalloid Amorphous Alloys by Mechanical Alloying and Mechanical Grinding Methods

    NASA Astrophysics Data System (ADS)

    Miura, Harumatsu; Isa, Shigeteru; Omuro, Keisuke

    1990-02-01

    Using a high energy ball mill, alloys of Fe40Ni40P14B6 and Fe40Ni40B20 were synthesized from crystalline, elemental iron and nickel metals and iron-metalloid alloys such as Fe-B and Fe-P by mechanical alloying (MA). Powders of the Fe40Ni40P14B6 alloy were also prepared from the cast ingot products by mechanical grinding (MG). Each of the MA and MG powder products showed a halo pattern typical of amorphous materials in the X-ray diffraction trace, and the crystallization enthalpy of the Fe40Ni40P14B6 MA powder, measured by differential scanning calorimetry, was almost the same as that of the melt-quenched sample of the same composition.

  8. Applicability of the one-step DVS method for the determination of amorphous amounts for further different hydrophilic and hydrophobic drugs.

    PubMed

    Müller, Thorsten; Scherließ, Regina; Schiewe, Jörg; Smal, Rüdiger; Weiler, Claudius; Steckel, Hartwig

    2015-08-01

    In a former publication the authors showed that low amounts of amorphous content (LOQ of 0.5%) in a hydrophobic model API (Ciclesonide) can be measured with an individually adjusted one-step dynamic organic vapor sorption (DVS). In this investigation the applicability is tested on various APIs which differ in lipophilicity (poor water solubility) and hygroscopicity (absorption of water). The vapor sorption method proved to be applicable in almost all cases. Moisture sorption isotherms were determined for all five investigated crystalline and amorphous APIs. However, it was necessary to select the parameters individually for each API. The used solvents (water, methanol, isopropanol and methylene chloride) and the humidity-levels (0.05 p/p0 until 0.5 p/p0) were chosen carefully because otherwise the amorphous amounts switch to their crystalline counterparts and are not detectable. The production of fully amorphous samples (absence of crystalline material measured by DSC, mDSC and XRPD) was optimized over several trials. As successfully methods proved ball-milling, freeze-drying, spray-drying and/or quench cooling. In the next step these fully amorphous amounts were blended with crystalline starting material to calibration curves (Turbula blender, influence of electrostatic charge to homogeneity) for the calculation of amorphous content. In summary, the following presented methods were used to determine and quantify low amorphous amounts (between 1.5% and 17.0%) in jet-milled powders (grinding pressure of 8bar, 1-3 grinding cycles), respectively.

  9. Microstructural characterization of Mg-based bulk metallic glass and nanocomposite

    SciTech Connect

    Babilas, Rafał; Nowosielski, Ryszard; Pawlyta, Mirosława; Fitch, Andy; Burian, Andrzej

    2015-04-15

    New magnesium-based bulk metallic glasses Mg{sub 60}Cu{sub 30}Y{sub 10} have been prepared by pressure casting. Glassy alloys were successfully annealed to become nanocomposite containing 200 nm crystallites in an amorphous matrix. The microstructure of bulk glassy alloy and nanocomposite obtained during heat treatment was examined by X-ray diffraction and scanning and high-resolution electron microscopy. Metallic glass has been also studied to explain the structural characteristics by the reverse Monte Carlo (RMC) modeling based on the diffraction data. The HRTEM images allow to indicate some medium-range order (MRO) regions about 2–3 nm in size and formation of local atomic clusters. The RMC modeling results confirmed some kinds of short range order (SRO) structures. It was found that the structure of bulk metallic glass formed by the pressure casting is homogeneous. The composite material contained very small particles in the amorphous matrix. Homogeneous glassy alloy had better corrosion resistance than a composite containing nanocrystalline particles in a glassy matrix. - Highlights: • RMC modeling demonstrates some kinds of SRO structures in Mg-based BMGs. • HRTEM indicated MRO regions about 2–3 nm and SRO regions about 0.5 nm in size. • Mg-based glassy alloys were successfully annealed to become nanocomposite material. • Crystalline particles have spherical morphology with an average diameter of 200 nm. • Glassy alloy had higher corrosion resistance than a nanocomposite sample.

  10. Phase transformation during mechano-synthesis of nanocrystalline/amorphous Fe–32Mn–6Si alloys

    SciTech Connect

    Amini, Rasool; Shamsipoor, Ali; Ghaffari, Mohammad; Alizadeh, Morteza; Okyay, Ali Kemal

    2013-10-15

    Mechano-synthesis of Fe–32Mn–6Si alloy by mechanical alloying of the elemental powder mixtures was evaluated by running the ball milling process under an inert argon gas atmosphere. In order to characterize the as-milled powders, powder sampling was performed at predetermined intervals from 0.5 to 192 h. X-ray florescence analyzer, X-ray diffraction, scanning electron microscope, and high resolution transmission electron microscope were utilized to investigate the chemical composition, structural evolution, morphological changes, and microstructure of the as-milled powders, respectively. According to the results, the nanocrystalline Fe–Mn–Si alloys were completely synthesized after 48 h of milling. Moreover, the formation of a considerable amount of amorphous phase during the milling process was indicated by quantitative X-ray diffraction analysis as well as high resolution transmission electron microscopy image and its selected area diffraction pattern. It was found that the α-to-γ and subsequently the amorphous-to-crystalline (especially martensite) phase transformation occurred by milling development. - Graphical abstract: Mechano-synthesis of nanocrystalline/amorphous Fe–32Mn–6Si shape memory alloys in the powder form: amorphous phase formation, α-to-γ phase transformation, mechano-crystallization of the amorphous, and martensite phase formation during the process. Highlights: • During MA, the α-to-γ phase transformation and amorphization occurred. • Mechano-crystallization of the amorphous phase occurred at sufficient milling time. • The formation of high amount of ε-martensite was evidenced at high milling times. • The platelet, spherical, and then irregular particle shapes was extended by MA. • By MA, the particles size was increased, then reduced, and afterward re-increased.

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

    NASA Astrophysics Data System (ADS)

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

    2012-10-01

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

  12. Effect of milling conditions on solid-state amorphization of glipizide, and characterization and stability of solid forms.

    PubMed

    Xu, Kailin; Xiong, Xinnuo; Zhai, Yuanming; Wang, Lili; Li, Shanshan; Yan, Jin; Wu, Di; Ma, Xiaoli; Li, Hui

    2016-09-10

    In this study, the amorphization of glipizide was systematically investigated through high-energy ball milling at different temperatures. The results of solid-state amorphization through milling indicated that glipizide underwent direct crystal-to-glass transformation at 15 and 25°C and crystal-to-glass-to-crystal conversion at 35°C; hence, milling time and temperature had significant effects on the amorphization of glipizide, which should be effectively controlled to obtain totally amorphous glipizide. Solid forms of glipizide were detailedly characterized through analyses of X-ray powder diffraction, morphology, thermal curves, vibrational spectra, and solid-state nuclear magnetic resonance. The physical stability of solid forms was investigated under different levels of relative humidity (RH) at 25°C. Forms I and III are kinetically stable and do not form any new solid-state forms at various RH levels. By contrast, Form II is kinetically unstable, undergoing direct glass-to-crystal transformation when RH levels higher than 32.8%. Therefore, stability investigation indicated that Form II should be stored under relatively dry conditions to prevent rapid crystallization. High temperatures can also induce the solid-state transformation of Form II; the conversion rate increased with increasing temperature.

  13. Micro-scale prediction method for API-solubility in polymeric matrices and process model for forming amorphous solid dispersion by hot-melt extrusion.

    PubMed

    Bochmann, Esther S; Neumann, Dirk; Gryczke, Andreas; Wagner, Karl G

    2016-10-01

    A new predictive micro-scale solubility and process model for amorphous solid dispersions (ASDs) by hot-melt extrusion (HME) is presented. It is based on DSC measurements consisting of an annealing step and a subsequent analysis of the glass transition temperature (Tg). The application of a complex mathematical model (BCKV-equation) to describe the dependency of Tg on the active pharmaceutical ingredient (API)/polymer ratio, enables the prediction of API solubility at ambient conditions (25°C). Furthermore, estimation of the minimal processing temperature for forming ASDs during HME trials could be defined and was additionally confirmed by X-ray powder diffraction data. The suitability of the DSC method was confirmed with melt rheological trials (small amplitude oscillatory system). As an example, ball milled physical mixtures of dipyridamole, indomethacin, itraconazole and nifedipine in poly(vinylpyrrolidone-co-vinylacetate) (copovidone) and polyvinyl caprolactam-polyvinyl acetate-polyethylene glycol graft copolymer (Soluplus®) were used.

  14. Amino acids as co-amorphous stabilizers for poorly water-soluble drugs--Part 2: molecular interactions.

    PubMed

    Löbmann, Korbinian; Laitinen, Riikka; Strachan, Clare; Rades, Thomas; Grohganz, Holger

    2013-11-01

    The formation of co-amorphous drug-drug mixtures has proved to be a powerful approach to stabilize the amorphous form and at the same time increase the dissolution of poorly water-soluble drugs. Molecular interactions in these co-amorphous formulations can play a crucial role in stabilization and dissolution enhancement. In this regard, Fourier-transform infrared spectroscopy (FTIR) is a valuable tool to analyze the molecular near range order of the compounds in the co-amorphous mixtures. In this study, several co-amorphous drugs--low molecular weight excipient blends--have been analyzed with FTIR spectroscopy. Molecular interactions of the drugs carbamazepine and indomethacin with the amino acids arginine, phenylalanine, and tryptophan were investigated. The amino acids were chosen from the biological target site of both drugs and prepared as co-amorphous formulations together with the drugs by vibrational ball milling. A detailed analysis of the FTIR spectra of these formulations revealed specific peak shifts in the vibrational modes of functional groups of drug and amino acid, as long as one amino acid from the biological target site was present in the blends. These peak shifts indicate that the drugs formed specific molecular interactions (hydrogen bonding and π-π interactions) with the amino acids. In the drug-amino acid mixtures that contained amino acids which were not present at the biological target site, no such interactions were identified. This study shows the potential of amino acids as small molecular weight excipients in co-amorphous formulations to stabilize the amorphous form of a poorly water-soluble drug through strong and specific molecular interactions with the drug. Copyright © 2013 Elsevier B.V. All rights reserved.

  15. The use of inverse phase gas chromatography to study the change of surface energy of amorphous lactose as a function of relative humidity and the processes of collapse and crystallisation.

    PubMed

    Newell, H E; Buckton, G; Butler, D A; Thielmann, F; Williams, D R

    2001-04-17

    The purpose of this study was to assess the effect of relative humidity (RH) on the surface energy of amorphous lactose. Two samples of amorphous lactose were investigated; a spray dried 100% amorphous material and a ball milled sample of crystalline lactose. The milled sample had less than 1% amorphous content by mass, but on investigation at 0% RH, yielded surface energies comparable to those obtained from the 100% amorphous material, indicating that the surface was amorphous. The effect of increasing humidity was to reduce the dispersive surface energy of the two samples from 36.0 +/- 0.14 and 41.6 +/- 1.4 mJ m(-2) at 0% RH for the spray dried and milled samples respectively, to a value comparable to that obtained for the crystalline alpha-lactose monohydrate of 31.3 +/- 0.41 mJ m(-2). The change in surface energy due to water sorption was only reversible up to 20% RH; after exposure to higher RH values subsequent drying did not result in a return to the original surface energy of the amorphous form. This shows that the surface is reorganising as the glass transition temperature (Tg) is reduced, even though the sample has not collapsed or crystallised. It was possible to follow the collapse behaviour in the column with ease, using a number of different methods.

  16. Surface functionalized amorphous nanosilica and microsilica with nanopores as promising tools in biomedicine

    NASA Astrophysics Data System (ADS)

    Rahman, Ayesha; Seth, Dipankar; Mukhopadhyaya, Sunit K.; Brahmachary, Ratan L.; Ulrichs, Christian; Goswami, Arunava

    2009-01-01

    Cellular interactions with engineered nanoparticles (NPs) are dependent on many properties, inherent to the nanoparticle (viz. size, shape, surface characteristics, degradation, agglomeration/dispersal, and charge, etc.). Modification of the surface reactivity via surface functionalization of the nanoparticles to be targeted seems to be important. Utilization of different surface functionalization methods of nanoparticles is an emerging field of basic and applied nanotechnology. It is well known that many disease-causing organisms induce host lipids and if deprived, their growth is inhibited in vivo. Amorphous nanosilica (ANS) and amorphous microsilica with nanopores (AMS) were prepared by a combination of wet chemistry and high-energy ball milling. Lipophilic moieties were attached to both ANS and AMS via chemical surface functionalization method. Lipophilic ANS and AMS were found to inhibit the growth of Bombyx mori nuclear polyhedrosis virus (BmNPV) and chicken malarial parasites via absorption of silkworm hemolymph and chicken serum lipids/lipoproteins, respectively, in vivo. Therefore, intelligent surface functionalization of NP is an important concept, and its application in curing chicken malaria and BmNPV is presented here. Surface functionalization method reported in this paper might serve as a valuable technology for treating many diseases where pathogens induce host lipid.

  17. Field and temperature dependence of magnetization in FeCu-based amorphous alloys

    NASA Astrophysics Data System (ADS)

    Crespo, P.; Multigner, M.; Castaño, F. J.; Casero, R.; Hernando, A.; García Escorial, A.; Schultz, L.; Kaul, S. N.

    2000-06-01

    In this paper, the production of FeCu-based FeCuZr amorphous alloys by ball milling is reported. The thermal dependence of magnetization for the (Fe0.5Cu0.5)85Zr15 (at. %) amorphous alloy has been found to show a dramatic field dependence of the kink point of the magnetization. This kink corresponds to a temperature different from the Curie temperature, above 400 K, of the ferromagnetic phase, which, according to spin waves fitting, can be induced by applying external fields. Just above 235 K, the thermoremanence increases sharply, and this feature strongly suggests an increase of the ferromagnetic ordering under zero field heating. Neutron diffraction experiments seem to confirm the enhancement of spin alignment. The thermal expansion above the compensation temperature is proposed to be the origin of the thermoremanence enhancement through the anti-Invar effect as might be explained within the framework of recent ab initio calculations [M. van Schilfgaarde et al., Nature (London) 400, 46 (1999)].

  18. Early stages of mechanical crystallization of amorphous FeZrBCu soft magnetic material

    NASA Astrophysics Data System (ADS)

    Friedrich, J.; Herr, U.; Samwer, K.

    2000-03-01

    Nanocrystalline Fe-base soft magnetic materials with high saturation magnetization have been obtained by crystallization of FeZrBCu amorphous precursors. In contrast to the conventional thermal crystallization, mechanical crystallization provides an alternative route for the generation of nanocrystalline materials using a high energy ball mill. Special emphasis is put here on the early stages of the transformation. X-ray diffraction, Mössbauer spectroscopy, and magnetization measurements are used to characterize the material. We find a continuous increase of the saturation magnetization accompanied by an increase of the crystalline fraction. The coercivity shows a different behavior with a large increase after very short milling within the amorphous state and a decrease for long milling duration. The influence of the deformation process on the magnetic anisotropy and the coercivity is discussed in terms of stresses and shear band formation. The results are compared with the phase formation and magnetic properties of thermally crystallized FeZrBCu samples and mechanical crystallization studies of other materials.

  19. Surface functionalized amorphous nanosilica and microsilica with nanopores as promising tools in biomedicine.

    PubMed

    Rahman, Ayesha; Seth, Dipankar; Mukhopadhyaya, Sunit K; Brahmachary, Ratan L; Ulrichs, Christian; Goswami, Arunava

    2009-01-01

    Cellular interactions with engineered nanoparticles (NPs) are dependent on many properties, inherent to the nanoparticle (viz. size, shape, surface characteristics, degradation, agglomeration/dispersal, and charge, etc.). Modification of the surface reactivity via surface functionalization of the nanoparticles to be targeted seems to be important. Utilization of different surface functionalization methods of nanoparticles is an emerging field of basic and applied nanotechnology. It is well known that many disease-causing organisms induce host lipids and if deprived, their growth is inhibited in vivo. Amorphous nanosilica (ANS) and amorphous microsilica with nanopores (AMS) were prepared by a combination of wet chemistry and high-energy ball milling. Lipophilic moieties were attached to both ANS and AMS via chemical surface functionalization method. Lipophilic ANS and AMS were found to inhibit the growth of Bombyx mori nuclear polyhedrosis virus (BmNPV) and chicken malarial parasites via absorption of silkworm hemolymph and chicken serum lipids/lipoproteins, respectively, in vivo. Therefore, intelligent surface functionalization of NP is an important concept, and its application in curing chicken malaria and BmNPV is presented here. Surface functionalization method reported in this paper might serve as a valuable technology for treating many diseases where pathogens induce host lipid.

  20. Amorphization of ZrO2 + CeO2 Powders Through Mechanical Milling for the Use of Kinetic Spray

    NASA Astrophysics Data System (ADS)

    Li, Songlin; Wang, Lei; Xiong, Yuming; Bae, Gyuyeol; Lee, Changhee

    2013-12-01

    The coating formation in a kinetic spray process mainly depends on the impact of inflight particles at a high velocity. The plastic deformation at the impact interface would disrupt the native oxide scale on the particle and the substrate to generate the intimate contact of the atomic structures. Accordingly, it poses a challenge in producing ceramic coating during kinetic spray because of the lack of plasticity of ceramic powders at room temperature. In this study, we proposed to prepare ZrO2 ceramic coatings using partially amorphized powder with nanometer size in the kinetic spray process. To prepare the powder for the use of the kinetic spray, the amorphization and grain refinement of ZrO2 powder in mechanical ball milling were studied. The results showed that the amorphization and grain refinement were improved because of the formation of solid solution when the CeO2 agent was added. Subsequently, a nearly spherical powder was achieved via spray drying using the milled powders. The plasticity of the milled powders was tested in the kinetic spray process using Nitrogen as process gas. A dense ZrO2-CeO2 coating with a thickness of 50 μm was formed, whereas spraying milled ZrO2 powder can only lead to an inhomogeneous dispersion of the destructible particles on the surface of the substrate.

  1. Amorphous Polymeric Drug Salts as Ionic Solid Dispersion Forms of Ciprofloxacin.

    PubMed

    Mesallati, Hanah; Umerska, Anita; Paluch, Krzysztof J; Tajber, Lidia

    2017-07-03

    Ciprofloxacin (CIP) is a poorly soluble drug that also displays poor permeability. Attempts to improve the solubility of this drug to date have largely focused on the formation of crystalline salts and metal complexes. The aim of this study was to prepare amorphous solid dispersions (ASDs) by ball milling CIP with various polymers. Following examination of their solid state characteristics and physical stability, the solubility advantage of these ASDs was studied, and their permeability was investigated via parallel artificial membrane permeability assay (PAMPA). Finally, the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of the ASDs were compared to those of CIP. It was discovered that acidic polymers, such as Eudragit L100, Eudragit L100-55, Carbopol, and HPMCAS, were necessary for the amorphization of CIP. In each case, the positively charged secondary amine of CIP was found to interact with carboxylate groups in the polymers, forming amorphous polymeric drug salts. Although the ASDs began to crystallize within days under accelerated stability conditions, they remained fully X-ray amorphous following exposure to 90% RH at 25 °C, and demonstrated higher than predicted glass transition temperatures. The solubility of CIP in water and simulated intestinal fluid was also increased by all of the ASDs studied. Unlike a number of other solubility enhancing formulations, the ASDs did not decrease the permeability of the drug. Similarly, no decrease in antibiotic efficacy was observed, and significant improvements in the MIC and MBC of CIP were obtained with ASDs containing HPMCAS-LG and HPMCAS-MG. Therefore, ASDs may be a viable alternative for formulating CIP with improved solubility, bioavailability, and antimicrobial activity.

  2. Mg-based compounds for hydrogen and energy storage

    NASA Astrophysics Data System (ADS)

    Crivello, J.-C.; Denys, R. V.; Dornheim, M.; Felderhoff, M.; Grant, D. M.; Huot, J.; Jensen, T. R.; de Jongh, P.; Latroche, M.; Walker, G. S.; Webb, C. J.; Yartys, V. A.

    2016-02-01

    Magnesium-based alloys attract significant interest as cost-efficient hydrogen storage materials allowing the combination of high gravimetric storage capacity of hydrogen with fast rates of hydrogen uptake and release and pronounced destabilization of the metal-hydrogen bonding in comparison with binary Mg-H systems. In this review, various groups of magnesium compounds are considered, including (1) RE-Mg-Ni hydrides (RE = La, Pr, Nd); (2) Mg alloys with p-elements (X = Si, Ge, Sn, and Al); and (3) magnesium alloys with d-elements (Ti, Fe, Co, Ni, Cu, Zn, Pd). The hydrogenation-disproportionation-desorption-recombination process in the Mg-based alloys (LaMg12, LaMg11Ni) and unusually high-pressure hydrides synthesized at pressures exceeding 100 MPa (MgNi2H3) and stabilized by Ni-H bonding are also discussed. The paper reviews interrelations between the properties of the Mg-based hydrides and p- T conditions of the metal-hydrogen interactions, chemical composition of the initial alloys, their crystal structures, and microstructural state.

  3. Amorphic complexity

    NASA Astrophysics Data System (ADS)

    Fuhrmann, G.; Gröger, M.; Jäger, T.

    2016-02-01

    We introduce amorphic complexity as a new topological invariant that measures the complexity of dynamical systems in the regime of zero entropy. Its main purpose is to detect the very onset of disorder in the asymptotic behaviour. For instance, it gives positive value to Denjoy examples on the circle and Sturmian subshifts, while being zero for all isometries and Morse-Smale systems. After discussing basic properties and examples, we show that amorphic complexity and the underlying asymptotic separation numbers can be used to distinguish almost automorphic minimal systems from equicontinuous ones. For symbolic systems, amorphic complexity equals the box dimension of the associated Besicovitch space. In this context, we concentrate on regular Toeplitz flows and give a detailed description of the relation to the scaling behaviour of the densities of the p-skeletons. Finally, we take a look at strange non-chaotic attractors appearing in so-called pinched skew product systems. Continuous-time systems, more general group actions and the application to cut and project quasicrystals will be treated in subsequent work.

  4. Overview of Amorphous and Nanocrystalline Magnetocaloric Materials Operating Near Room Temperature

    NASA Astrophysics Data System (ADS)

    Ucar, Huseyin; Ipus, John J.; Franco, V.; McHenry, M. E.; Laughlin, D. E.

    2012-07-01

    The observation of a giant magnetocaloric effect in Gd5Ge1.9Si2Fe0.1 has stimulated the magnetocaloric research in the last two decades. However, the high price of Gd and its proclivity to corrosion of these compounds have prevented their commercial use. To reduce raw materials cost, transition metal-based alloys are investigated to replace rare earth-based materials. Environmental considerations, substitution for scarce and strategic elements, and cost considerations all speak to potential contributions of these new materials to sustainability. Fe-based soft amorphous alloys are believed to be promising magnetic refrigerants. Efforts in improving the refrigeration capacity (RC) of refrigerants mainly rely on broadening the magnetic entropy change. One promising technique is to couple two phases of magnetic materials with desirable properties. Second is the investigation of nanoparticle synthesis routes, with ball milling being the most widely used one. The motivation for the nanoparticles synthesis is rooted in their inherent tendency to have distributed exchange coupling, which will broaden the magnetic entropy curve. As proven with the cost analysis, the focus is believed to shift from improving the RC of refrigerants toward finding the most economically advantageous magnetic refrigerant with the highest performance.

  5. Exploring several different routes to produce Mg- based nanomaterials for Hydrogen storage

    NASA Astrophysics Data System (ADS)

    Leiva, D. R.; Chanchetti, L. F.; Floriano, R.; Ishikawa, T. T.; Botta, W. J.

    2014-08-01

    Severe mechanical processing routes based on high-energy ball milling (HEBM) or severe plastic deformation (SPD) can be used to produce Mg nanomaterials for hydrogen storage applications. In the last few years, we have been exploring in our research group different SPD processing routes in Mg systems to achieve good activation (first hydrogenation) and fast H-absorption/desorption kinetics, combined with enhanced air resistance. In this paper, we compare SPD techniques applied to Mg with HEBM applied to MgH2. Both advanced - melt spinning (MS), high-pressure torsion (HPT) - and more conventional - cold rolling (CR), cold forging (CF)- techniques are evaluated as means of production of bulk samples with very refined microstructures and controlled textures. In the best SPD processing conditions, attractive H-absorption/desorption kinetic properties are obtained, which are comparable to the ones of MgH2 milled powders, even if the needed temperatures are higher - 350°C compared to 300°C.CR and CF stand out as the processes with higher potential for industrial application, considering the level of the attained hydrogen storage properties, its simplicity and low cost.

  6. Hydrogenation reaction of Mg-Based alloys fabricated by rapid solidification

    NASA Astrophysics Data System (ADS)

    Song, MyoungYoup; Kwon, SungNam; Mumm, Daniel R.; Park, Hye Ryoung

    2013-03-01

    Mg-23.5wt%Ni-xwt%Cu (x=2.5, 5 and 7.5) alloys for hydrogen storage were prepared by melt spinning and crystallization heat treatment. The alloys were ground by a planetary ball mill for 2 h in order to obtain a fine powder. The Mg-23.5Ni-5Cu alloy had crystalline Mg and Mg2Ni phases. Mg-23.5Ni-5Cu had an effective hydrogen capacity of near 5 wt%. The activated Mg-23.5Ni-5Cu alloy absorbed 4.50 and 4.84 wt%H at 573K under 12 bar H2 for 10 and 60 min, respectively, and desorbed 3. 21 and 4.81 wt%H at 573K under 1.0 bar H2 for 10 and 30 min, respectively. The activated Mg-23.5Ni-5Cu alloy showed a quite high hydriding rate like Mg-10Fe2O3, and higher dehydriding rates than the activated Mg-xFe2O3-yNi. This likely resulted because the melting before melt spinning process has led to the homogeneous distribution of Ni and Cu in the melted Mg, and the Mg-23.5Ni-5Cu alloy has a larger amount of the Mg2Ni phase than the Mg-xFe2O3-yNi alloy.

  7. Influence of small amorphous amounts in hydrophilic and hydrophobic APIs on storage stability of dry powder inhalation products.

    PubMed

    Müller, Thorsten; Krehl, Regina; Schiewe, Jörg; Weiler, Claudius; Steckel, Hartwig

    2015-05-01

    The effects of different manufacturing methods to induce formation of amorphous content, changes of physico-chemical characteristics of powder blends and changes of aerodynamic properties over storage time (6months) analyzed with the Next Generation Impactor (NGI) are investigated. Earlier studies have shown that standard pharmaceutical operations lead to structural disorders which may influence drug delivery and product stability. In this investigation, fully amorphous drug samples produced by spray-drying (SD) and ball-milling (BM) as well as semi-crystalline samples (produced by blending and micronization) are studied and compared to fully crystalline starting material. The amorphous content of these hydrophilic and hydrophobic active pharmaceutical ingredients (APIs) was determined using a validated one-step DVS-method. For the conducted blending and micronization tests, amorphous amounts up to a maximum of 5.1% for salbutamol sulfate (SBS) and 17.0% for ciclesonide (CS) were measured. In order to investigate the impact of small amorphous amounts, inhalable homogenous powder mixtures with very high and low amorphous content and a defined particle size were prepared with a Turbula blender for each API. These blends were stored (6months, 45% RH, room temperature) to evaluate the influence of amorphous amounts on storage stability. The fine particle fraction (FPF: % of emitted dose<5μm) was determined with the NGI at defined time points. The amorphous amounts showed a major effect on dispersion behavior, the mixtures of the two APIs showed differences at the beginning of the study and significant differences in storage stability. The FPF values for SBS decreased during storage (FPF: from 35% to <27%) for the blend with high amorphous amounts, in contrast the initially re-crystallized sample achieved a comparable constant level of about 25%. For the hydrophobic CS a constantly increasing FPF (from 6% to >15%) over storage time for both types of blends was

  8. Synthesis of bulk nanostructured aluminum containing in situ crystallized amorphous particles

    NASA Astrophysics Data System (ADS)

    Zhang, Zhihui

    5083 Al containing in situ crystallized Al85Ni10La 5 amorphous particles (10% and 20% in volume fraction) was synthesized through a powder metallurgy route consisting of cold isostatic pressing, degassing and hot extrusion. The nanostructured 5083 Al powders (grain size ˜28 nm) were produced through mechanical milling in liquid nitrogen. The Al 85Ni10La5 powders were produced via gas atomization using helium gas and the fraction in the size range of <500 mesh (<25 mum), which appeared to be fully amorphous on the basis of X-ray diffraction studies, was isolated for further investigation. The amorphous Al85Ni10La5 alloy exhibited a glass transition at ˜259°C (at a heating rate of 40°C/min) and nanoscale crystallites (< 100 nm) with an equiaxed morphology formed during the subsequent crystallization reactions. At temperatures higher than 283°C, only the equilibrium phases Al, Al3Ni and Al11La 3 were formed. An unusually high nucleation density (1021-22 /m3) was recorded in the crystallization process. The copious nucleation sites were rationalized from the presence of quenched-in Al nuclei, which were evidenced by isothermal calorimetric tracing (235°C) and a direct HRTEM observation of the amorphous Al85Ni10La 5 powders. The feasibility of preparation of nanocrystalline/amorphous particles via melt spinning followed by ball milling was also studied. In the as-extruded composites, the amorphous Al85Ni10 La5 particles underwent complete crystallization resulting in a grain size of 100 ˜ 200 nm; the 5083 Al matrix had a grain size around 200 nm in the fine-grained region interspersed by coarse-grained region with a grain size of 600 ˜ 1500 nm. A metallurgical bond formed between the 5083 Al matrix and Al85Ni10La5 particles showing a grain-boundary-like interface. The compressive fracture strength of the as-extruded 10% and 20% Al85Ni10La5 composites were determined to be 1025 MPa and 837 MPa, respectively. The influence of secondary processing, i.e., swaging

  9. Amorphous metal composites

    DOEpatents

    Byrne, Martin A.; Lupinski, John H.

    1984-01-01

    An improved amorphous metal composite and process of making the composite. The amorphous metal composite comprises amorphous metal (e.g. iron) and a low molecular weight thermosetting polymer binder. The process comprises placing an amorphous metal in particulate form and a thermosetting polymer binder powder into a container, mixing these materials, and applying heat and pressure to convert the mixture into an amorphous metal composite.

  10. Chemical pretreatment of coal in a stirred ball mill

    SciTech Connect

    Birlingmair, D.; Chmielewski, T.; Pollard, J.

    1989-10-01

    Present studies on the electrochemical aspects of pyrite flotation in the presence of reducing agents were conducted to explain the effects observed during flotation of the separated organic and mineral-rich fractions of coal independently when sodium dithionite was used as an additive during and after grinding. In addition, the electrochemical phenomena occurring on the surface of pyrites of different origin was studied to aid in explaining the differences observed in the flotation of various coal-derived pyrite samples. Potentiometric and voltametric measurements have been conducted on electrodes prepared from natural pyrite samples of mineral and coal origin. Voltametric curves recorded on FeS{sub 2} electrodes indicate the presence of elemental sulfur, iron-oxy, and iron-hydroxy compounds, even on the freshly prepared surfaces. Comparison of voltametric curves with results of potentiometric measurements show that in the presence of dithionite several electrochemical processes are expected to take place on the pyrite surface. Voltametric curves recorded in solutions of different pH with and without sodium dithionite demonstrate that pyrite is a very good electrocatalyst in the anodic oxidation of dithionite. 13 refs., 12 figs.

  11. Attempted - to -Phase Conversion of Croconic Acid via Ball Milling

    DTIC Science & Technology

    2017-05-18

    Jenkins Weapons and Materials Research Directorate, ARL Approved for public release; distribution is unlimited. ii...high-pressure phase change in croconic acid (CA), which is being investigated as a potential novel energetic material . High-speed video of the milling...calorimetry was used to determine what effect varying the ball-to-sample mass ratio and milling time had on the energy content of the milled material

  12. Increasing biochar surface area: Optimization of ball milling parameters

    USDA-ARS?s Scientific Manuscript database

    Biochar produced from corn stover is a renewable, plentiful source of carbon that is a potential substitute for carbon black as rubber composite filler and also as binder/filter media for water or beverage purification applications. However, to be successful in these applications, the surface area o...

  13. Theory of amorphous ices

    PubMed Central

    Limmer, David T.; Chandler, David

    2014-01-01

    We derive a phase diagram for amorphous solids and liquid supercooled water and explain why the amorphous solids of water exist in several different forms. Application of large-deviation theory allows us to prepare such phases in computer simulations. Along with nonequilibrium transitions between the ergodic liquid and two distinct amorphous solids, we establish coexistence between these two amorphous solids. The phase diagram we predict includes a nonequilibrium triple point where two amorphous phases and the liquid coexist. Whereas the amorphous solids are long-lived and slowly aging glasses, their melting can lead quickly to the formation of crystalline ice. Further, melting of the higher density amorphous solid at low pressures takes place in steps, transitioning to the lower-density glass before accessing a nonequilibrium liquid from which ice coarsens. PMID:24858957

  14. Method for measuring surface activity of silicon nitride powder

    NASA Technical Reports Server (NTRS)

    Kanno, Y.; Imai, H.

    1985-01-01

    Amorphous, alpha-, and beta-Si3N4 powders were activated by vibration ball milling in purified MeOH, and the surface activity of ground powders was determined by the temperature programmed desorption (TPD) method using NH3 gas. The concentration of active sites with a potential energy equivalent to the peak temperature in the spectrum increased was markedly by ball milling the amorphous Si3N4. The alpha- and beta-Si3N4 also had active sites produced by ball milling. The concentration of active site increased with increased ball milling time. A method for measuring surface activity of ceramic raw materials by TPD is proposed.

  15. Nanocrystal dispersed amorphous alloys

    NASA Technical Reports Server (NTRS)

    Perepezko, John H. (Inventor); Allen, Donald R. (Inventor); Foley, James C. (Inventor)

    2001-01-01

    Compositions and methods for obtaining nanocrystal dispersed amorphous alloys are described. A composition includes an amorphous matrix forming element (e.g., Al or Fe); at least one transition metal element; and at least one crystallizing agent that is insoluble in the resulting amorphous matrix. During devitrification, the crystallizing agent causes the formation of a high density nanocrystal dispersion. The compositions and methods provide advantages in that materials with superior properties are provided.

  16. Tritium in amorphous silicon

    SciTech Connect

    Sidhu, L.S.; Kosteski, T.; O`Leary, S.K.; Gaspari, F.; Zukotynski, S.; Kherani, N.P.; Shmadya, W.

    1996-12-31

    Preliminary results on infrared and luminescence measurements of tritium incorporated amorphous silicon are reported. Tritium is an unstable isotope that readily substitutes hydrogen in the amorphous silicon network. Due to its greater mass, bonded tritium is found to introduce new stretching modes in the infrared spectrum. Inelastic collisions between the beta particles, produced as a result of tritium decay, and the amorphous silicon network, results in the generation of excess electron-hole pairs. Radiative recombination of these carriers is observed.

  17. Thermodynamic Tuning of Mg-Based Hydrogen Storage Alloys: A Review

    PubMed Central

    Zhu, Min; Lu, Yanshan; Ouyang, Liuzhang; Wang, Hui

    2013-01-01

    Mg-based hydrides are one of the most promising hydrogen storage materials because of their relatively high storage capacity, abundance, and low cost. However, slow kinetics and stable thermodynamics hinder their practical application. In contrast to the substantial progress in the enhancement of the hydrogenation/dehydrogenation kinetics, thermodynamic tuning is still a great challenge for Mg-based alloys. At present, the main strategies to alter the thermodynamics of Mg/MgH2 are alloying, nanostructuring, and changing the reaction pathway. Using these approaches, thermodynamic tuning has been achieved to some extent, but it is still far from that required for practical application. In this article, we summarize the advantages and disadvantages of these strategies. Based on the current progress, finding reversible systems with high hydrogen capacity and effectively tailored reaction enthalpy offers a promising route for tuning the thermodynamics of Mg-based hydrogen storage alloys. PMID:28788353

  18. Trehalose amorphization and recrystallization.

    PubMed

    Sussich, Fabiana; Cesàro, Attilio

    2008-10-13

    The stability of the amorphous trehalose prepared by using several procedures is presented and discussed. Amorphization is shown to occur by melting (T(m)=215 degrees C) or milling (room temperature) the crystalline anhydrous form TRE-beta. Fast dehydration of the di-hydrate crystalline polymorph, TRE-h, also produces an amorphous phase. Other dehydration procedures of TRE-h, such as microwave treatment, supercritical extraction or gentle heating at low scan rates, give variable fractions of the polymorph TRE-alpha, that undergo amorphization upon melting (at lower temperature, T(m)=130 degrees C). Additional procedures for amorphization, such as freeze-drying, spray-drying or evaporation of trehalose solutions, are discussed. All these procedures are classified depending on the capability of the undercooled liquid phase to undergo cold crystallization upon heating the glassy state at temperatures above the glass transition temperature (T(g)=120 degrees C). The recrystallizable amorphous phase is invariably obtained by the melt of the polymorph TRE-alpha, while other procedures always give an amorphous phase that is unable to crystallize above T(g). The existence of two different categories is analyzed in terms of the transformation paths and the hypothesis that the systems may exhibit different molecular mobilities.

  19. Hydrogen in amorphous silicon

    SciTech Connect

    Peercy, P. S.

    1980-01-01

    The structural aspects of amorphous silicon and the role of hydrogen in this structure are reviewed with emphasis on ion implantation studies. In amorphous silicon produced by Si ion implantation of crystalline silicon, the material reconstructs into a metastable amorphous structure which has optical and electrical properties qualitatively similar to the corresponding properties in high-purity evaporated amorphous silicon. Hydrogen studies further indicate that these structures will accomodate less than or equal to 5 at.% hydrogen and this hydrogen is bonded predominantly in a monohydride (SiH/sub 1/) site. Larger hydrogen concentrations than this can be achieved under certain conditions, but the excess hydrogen may be attributed to defects and voids in the material. Similarly, glow discharge or sputter deposited amorphous silicon has more desirable electrical and optical properties when the material is prepared with low hydrogen concentration and monohydride bonding. Results of structural studies and hydrogen incorporation in amorphous silicon were discussed relative to the different models proposed for amorphous silicon.

  20. Amorphous pharmaceutical solids.

    PubMed

    Vranić, Edina

    2004-07-01

    Amorphous forms are, by definition, non-crystalline materials which possess no long-range order. Their structure can be thought of as being similar to that of a frozen liquid with the thermal fluctuations present in a liquid frozen out, leaving only "static" structural disorder. The amorphous solids have always been an essential part of pharmaceutical research, but the current interest has been raised by two developments: a growing attention to pharmaceutical solids in general, especially polymorphs and solvates and a revived interest in the science of glasses and the glass transition. Amorphous substances may be formed both intentionally and unintentionally during normal pharmaceutical manufacturing operations. The properties of amorphous materials can be exploited to improve the performance of pharmaceutical dosage forms, but these properties can also give rise to unwanted effects that need to be understood and managed in order for the systems to perform as required.

  1. Amorphous diamond films

    DOEpatents

    Falabella, S.

    1998-06-09

    Amorphous diamond films having a significant reduction in intrinsic stress are prepared by biasing a substrate to be coated and depositing carbon ions thereon under controlled temperature conditions. 1 fig.

  2. Study of reactions of activated Mg-based powders in heated steam

    NASA Astrophysics Data System (ADS)

    Huang, Hai-tao; Zou, Mei-shuai; Guo, Xiao-yan; Yang, Rong-jie; Li, Yun-kai

    2014-01-01

    Activated Mg-based powders are prepared by high-energy milling and characterised with XRD, SEM, TG and BET techniques. This study focus on reactions of Mg-based powders with flowing steam that is heated at 500, 600, and 700 °C in a transparent pipe furnace. Morphologies and phases of solid reaction products are analysed by SEM, XRD, and residual metal content, and ignition delay times are measured. Experimental results show that all Mg-based powders oxidise at 500 °C and ignite at 600 °C. At 700 °C, all samples burn completely to form magnesium oxide (MgO) within 5 min. Residual metal contents and ignition delay times of all samples decrease with increasing temperature, and ignition delay times of activated Mg-based materials containing cobalto-cobaltic oxide (Co3O4) are only 22 s at 700 °C. Milled Mg powders are more reactive in heated steam than unmilled Mg powders, and the addition of Co3O4 further increases magnesium reactivity in heated steam.

  3. Amorphous metal alloy

    DOEpatents

    Wang, R.; Merz, M.D.

    1980-04-09

    Amorphous metal alloys of the iron-chromium and nickel-chromium type have excellent corrosion resistance and high temperature stability and are suitable for use as a protective coating on less corrosion resistant substrates. The alloys are stabilized in the amorphous state by one or more elements of titanium, zirconium, hafnium, niobium, tantalum, molybdenum, and tungsten. The alloy is preferably prepared by sputter deposition.

  4. Formation of amorphous materials

    DOEpatents

    Johnson, William L.; Schwarz, Ricardo B.

    1986-01-01

    Metastable amorphous or fine crystalline materials are formed by solid state reactions by diffusion of a metallic component into a solid compound or by diffusion of a gas into an intermetallic compound. The invention can be practiced on layers of metals deposited on an amorphous substrate or by intermixing powders with nucleating seed granules. All that is required is that the diffusion of the first component into the second component be much faster than the self-diffusion of the first component. The method is practiced at a temperature below the temperature at which the amorphous phase transforms into one or more crystalline phases and near or below the temperature at which the ratio of the rate of diffusion of the first component to the rate of self-diffusion is at least 10.sup.4. This anomalous diffusion criteria is found in many binary, tertiary and higher ordered systems of alloys and appears to be found in all alloy systems that form amorphous materials by rapid quenching. The method of the invention can totally convert much larger dimensional materials to amorphous materials in practical periods of several hours or less.

  5. Structural Amorphous Steels

    NASA Astrophysics Data System (ADS)

    Lu, Z. P.; Liu, C. T.; Thompson, J. R.; Porter, W. D.

    2004-06-01

    Recent advancement in bulk metallic glasses, whose properties are usually superior to their crystalline counterparts, has stimulated great interest in fabricating bulk amorphous steels. While a great deal of effort has been devoted to this field, the fabrication of structural amorphous steels with large cross sections has remained an alchemist’s dream because of the limited glass-forming ability (GFA) of these materials. Here we report the discovery of structural amorphous steels that can be cast into glasses with large cross-section sizes using conventional drop-casting methods. These new steels showed interesting physical, magnetic, and mechanical properties, along with high thermal stability. The underlying mechanisms for the superior GFA of these materials are discussed.

  6. Surface treatments for controlling corrosion rate of biodegradable Mg and Mg-based alloy implants

    PubMed Central

    Uddin, M S; Hall, Colin; Murphy, Peter

    2015-01-01

    Due to their excellent biodegradability characteristics, Mg and Mg-based alloys have become an emerging material in biomedical implants, notably for repair of bone as well as coronary arterial stents. However, the main problem with Mg-based alloys is their rapid corrosion in aggressive environments such as human bodily fluids. Previously, many approaches such as control of alloying materials, composition and surface treatments, have been attempted to regulate the corrosion rate. This article presents a comprehensive review of recent research focusing on surface treatment techniques utilised to control the corrosion rate and surface integrity of Mg-based alloys in both in vitro and in vivo environments. Surface treatments generally involve the controlled deposition of thin film coatings using various coating processes, and mechanical surfacing such as machining, deep rolling or low plasticity burnishing. The aim is to either make a protective thin layer of a material or to change the micro-structure and mechanical properties at the surface and sub-surface levels, which will prevent rapid corrosion and thus delay the degradation of the alloys. We have organised the review of past works on coatings by categorising the coatings into two classes—conversion and deposition coatings—while works on mechanical treatments are reviewed based on the tool-based processes which affect the sub-surface microstructure and mechanical properties of the material. Various types of coatings and their processing techniques under two classes of coating and mechanical treatment approaches have been analysed and discussed to investigate their impact on the corrosion performance, biomechanical integrity, biocompatibility and cell viability. Potential challenges and future directions in designing and developing the improved biodegradable Mg/Mg-based alloy implants were addressed and discussed. The literature reveals that no solutions are yet complete and hence new and innovative approaches

  7. Surface treatments for controlling corrosion rate of biodegradable Mg and Mg-based alloy implants.

    PubMed

    Uddin, M S; Hall, Colin; Murphy, Peter

    2015-10-01

    Due to their excellent biodegradability characteristics, Mg and Mg-based alloys have become an emerging material in biomedical implants, notably for repair of bone as well as coronary arterial stents. However, the main problem with Mg-based alloys is their rapid corrosion in aggressive environments such as human bodily fluids. Previously, many approaches such as control of alloying materials, composition and surface treatments, have been attempted to regulate the corrosion rate. This article presents a comprehensive review of recent research focusing on surface treatment techniques utilised to control the corrosion rate and surface integrity of Mg-based alloys in both in vitro and in vivo environments. Surface treatments generally involve the controlled deposition of thin film coatings using various coating processes, and mechanical surfacing such as machining, deep rolling or low plasticity burnishing. The aim is to either make a protective thin layer of a material or to change the micro-structure and mechanical properties at the surface and sub-surface levels, which will prevent rapid corrosion and thus delay the degradation of the alloys. We have organised the review of past works on coatings by categorising the coatings into two classes-conversion and deposition coatings-while works on mechanical treatments are reviewed based on the tool-based processes which affect the sub-surface microstructure and mechanical properties of the material. Various types of coatings and their processing techniques under two classes of coating and mechanical treatment approaches have been analysed and discussed to investigate their impact on the corrosion performance, biomechanical integrity, biocompatibility and cell viability. Potential challenges and future directions in designing and developing the improved biodegradable Mg/Mg-based alloy implants were addressed and discussed. The literature reveals that no solutions are yet complete and hence new and innovative approaches are

  8. Amorphous silicon photovoltaic devices

    DOEpatents

    Carlson, David E.; Lin, Guang H.; Ganguly, Gautam

    2004-08-31

    This invention is a photovoltaic device comprising an intrinsic or i-layer of amorphous silicon and where the photovoltaic device is more efficient at converting light energy to electric energy at high operating temperatures than at low operating temperatures. The photovoltaic devices of this invention are suitable for use in high temperature operating environments.

  9. Disorder-induced amorphization

    SciTech Connect

    Lam, N.Q.; Okamoto, P.R.; Li, Mo

    1997-03-01

    Many crystalline materials undergo a crystalline-to-amorphous (c-a) phase transition when subjected to energetic particle irradiation at low temperatures. By focusing on the mean-square static atomic displacement as a generic measure of chemical and topological disorder, we are led quite naturally to a generalized version of the Lindemann melting criterion as a conceptual framework for a unified thermodynamic approach to solid-state amorphizing transformations. In its simplest form, the generalized Lindemann criterion assumes that the sum of the static and dynamic mean-square atomic displacements is constant along the polymorphous melting curve so that c-a transformations can be understood simply as melting of a critically-disordered crystal at temperatures below the glass transition temperature where the supercooled liquid can persist indefinitely in a configurationally-frozen state. Evidence in support of the generalized Lindemann melting criterion for amorphization is provided by a large variety of experimental observations and by molecular dynamics simulations of heat-induced melting and of defect-induced amorphization of intermetallic compounds.

  10. Amorphous semiconductor solar cell

    DOEpatents

    Dalal, Vikram L.

    1981-01-01

    A solar cell comprising a back electrical contact, amorphous silicon semiconductor base and junction layers and a top electrical contact includes in its manufacture the step of heat treating the physical junction between the base layer and junction layer to diffuse the dopant species at the physical junction into the base layer.

  11. Estimation of thermodynamic parameters for Au- and Mg-based metallic glasses

    NASA Astrophysics Data System (ADS)

    Gaur, Jitendra; Mishra, R. K.

    2017-10-01

    The study of temperature dependent thermodynamic parameters; Gibb's free energy difference (ΔG), entropy difference (ΔS) and enthalpy difference (ΔH) between the undercooled liquid and the corresponding equilibrium solid phases has been proved to be extremely advantageous in the study of the thermodynamic behaviour of Metallic glass (MG) forming melts. In last two decades, Au- and Mg-based alloys were found to form glass phases. In present study, the three thermodynamic parameters viz., ΔG, ΔS and ΔH are calculated theoretically in the entire temperature range Tm (melting temperature) to Tg (glass transition temperature) for both Au- and Mg-based five samples of MGs; Au77Ge13.6Si9.4, Au53.2Pb27.5Sb19.3, Au81.4Si18.6, Mg85.5Cu14.5 and Mg81.6Ga18.4 on the basis of Taylor's series expansion. A relative study is also made between the present result and the result obtained experimentally as well as on the basis of expressions projected by the earlier researchers. An attempt is also been made to narrate the reduced glass transition temperature with glass forming ability for all five MGs.

  12. Synthesis and exceptional thermal stability of Mg-based bimetallic nanoparticles during hydrogenation.

    PubMed

    Krishnan, Gopi; Negrea, Raluca F; Ghica, Corneliu; ten Brink, Gert H; Kooi, Bart J; Palasantzas, George

    2014-10-21

    Here we report the extraordinary thermal stability of Mg rich bimetallic nanoparticles (NPs), which is important for hydrogen storage technology. The enhanced NP stability is accomplished because of two critical improvements: (i) no void development within NPs (nanoscale Kirkendall effect) during their formation and (ii) suppressed Mg evaporation and NP hollowing during Mg hydrogenation at elevated temperature. The mechanism leading to the improved thermal stability of Mg-based bimetallic NPs is shown to be due to MgH2 hydride formation before evaporation can take place. These findings were tested for various compositions of Mg with Ni, Cu, and Ti, which are interesting combinations of materials for hydrogen storage systems. To achieve this we first demonstrate the synthesis mechanism of Mg-Ni and Mg-Cu NPs, which is well controlled at the single particle level, in order to accomplish multi-shell, alloy and intermetallic structures of interest for hydrogen storage tests. Aberration corrected transmission electron microscopy was carried out to unravel the detailed atomic structure and composition of the bimetallic NPs after production, processing, and hydrogenation. Finally, a simple and effective methodology is proposed for tuning the composition of the Mg-based bimetallic NPs based on the temperature-dependent nucleation behavior of NPs in the gas-phase.

  13. Amorphous metallic foam

    NASA Astrophysics Data System (ADS)

    Schroers, Jan; Veazey, Chris; Johnson, William L.

    2003-01-01

    The bulk glass forming alloy Pd43Ni10Cu27P20 is processed into a low-density amorphous metallic foam. Pd43Ni10Cu27P20 is mixed with hydrated B2O3, which releases gas at elevated temperature and/or low pressure. Very homogeneous foams are achieved due to the high viscosity of the alloy even at its liquidus temperature. By processing at the liquidus temperature and decreasing the pressure to 10-2 mbar, well-distributed bubbles expand to foam the material. Foam densities as low as 1.4×103 kg/m3 were obtained, corresponding to a bubble volume fraction of 84%. The bubble diameter ranges between 2×10-4 and 1×10-3 m. Thermal analysis by differential scanning calorimetry confirms the amorphous nature of the foam. Furthermore, it reveals that the foam's thermal stability is comparable to the bulk material.

  14. Amorphous silicon radiation detectors

    DOEpatents

    Street, Robert A.; Perez-Mendez, Victor; Kaplan, Selig N.

    1992-01-01

    Hydrogenated amorphous silicon radiation detector devices having enhanced signal are disclosed. Specifically provided are transversely oriented electrode layers and layered detector configurations of amorphous silicon, the structure of which allow high electric fields upon application of a bias thereby beneficially resulting in a reduction in noise from contact injection and an increase in signal including avalanche multiplication and gain of the signal produced by incoming high energy radiation. These enhanced radiation sensitive devices can be used as measuring and detection means for visible light, low energy photons and high energy ionizing particles such as electrons, x-rays, alpha particles, beta particles and gamma radiation. Particular utility of the device is disclosed for precision powder crystallography and biological identification.

  15. Amorphous silicon radiation detectors

    DOEpatents

    Street, R.A.; Perez-Mendez, V.; Kaplan, S.N.

    1992-11-17

    Hydrogenated amorphous silicon radiation detector devices having enhanced signal are disclosed. Specifically provided are transversely oriented electrode layers and layered detector configurations of amorphous silicon, the structure of which allow high electric fields upon application of a bias thereby beneficially resulting in a reduction in noise from contact injection and an increase in signal including avalanche multiplication and gain of the signal produced by incoming high energy radiation. These enhanced radiation sensitive devices can be used as measuring and detection means for visible light, low energy photons and high energy ionizing particles such as electrons, x-rays, alpha particles, beta particles and gamma radiation. Particular utility of the device is disclosed for precision powder crystallography and biological identification. 13 figs.

  16. Defects in Amorphous Metals.

    DTIC Science & Technology

    1982-07-01

    this map with a similar plot of the experimental data. An experimental deformation data map for Pd-based amorphous al- loys is shown in fig. 10. In the...Masumoto. I Mat. Sci. 12 (1977) 1927, [IgI T M Ha.es. J. W Allen. J. Tauc . B. C. Giessen and J. J. Hauser. Phys. Re. Lett. 41 i197s) 1282 [191 J

  17. Synthesis and exceptional thermal stability of Mg-based bimetallic nanoparticles during hydrogenation

    NASA Astrophysics Data System (ADS)

    Krishnan, Gopi; Negrea, Raluca F.; Ghica, Corneliu; Ten Brink, Gert H.; Kooi, Bart J.; Palasantzas, George

    2014-09-01

    Here we report the extraordinary thermal stability of Mg rich bimetallic nanoparticles (NPs), which is important for hydrogen storage technology. The enhanced NP stability is accomplished because of two critical improvements: (i) no void development within NPs (nanoscale Kirkendall effect) during their formation and (ii) suppressed Mg evaporation and NP hollowing during Mg hydrogenation at elevated temperature. The mechanism leading to the improved thermal stability of Mg-based bimetallic NPs is shown to be due to MgH2 hydride formation before evaporation can take place. These findings were tested for various compositions of Mg with Ni, Cu, and Ti, which are interesting combinations of materials for hydrogen storage systems. To achieve this we first demonstrate the synthesis mechanism of Mg-Ni and Mg-Cu NPs, which is well controlled at the single particle level, in order to accomplish multi-shell, alloy and intermetallic structures of interest for hydrogen storage tests. Aberration corrected transmission electron microscopy was carried out to unravel the detailed atomic structure and composition of the bimetallic NPs after production, processing, and hydrogenation. Finally, a simple and effective methodology is proposed for tuning the composition of the Mg-based bimetallic NPs based on the temperature-dependent nucleation behavior of NPs in the gas-phase.Here we report the extraordinary thermal stability of Mg rich bimetallic nanoparticles (NPs), which is important for hydrogen storage technology. The enhanced NP stability is accomplished because of two critical improvements: (i) no void development within NPs (nanoscale Kirkendall effect) during their formation and (ii) suppressed Mg evaporation and NP hollowing during Mg hydrogenation at elevated temperature. The mechanism leading to the improved thermal stability of Mg-based bimetallic NPs is shown to be due to MgH2 hydride formation before evaporation can take place. These findings were tested for various

  18. Magnesium (Mg) based interference screws developed for promoting tendon graft incorporation in bone tunnel in rabbits.

    PubMed

    Wang, Jiali; Xu, Jiankun; Song, Bin; Chow, Dick Hokiu; Shu-Hang Yung, Patrick; Qin, Ling

    2017-09-14

    How to enhance tendon graft incorporation into bone tunnels for achieving satisfactory healing outcomes in patients with anterior cruciate ligament reconstruction (ACLR) is one of the most challenging clinical problems in orthopaedic sports medicine. Several studies have recently reported the beneficial effects of Mg implants in bone fracture healing, indicating the use potential of Mg devices in promoting the tendon graft osteointegration. Here, we developed an innovative Mg-based interference screws for fixation of the tendon graft in rabbits underwent ACLR and investigated the biological role of Mg-based implants in the graft healing. The titanium (Ti) interference screw was used as the control. We demonstrated that Mg interference screw significantly accelerated the incorporation of the tendon graft into bone tunnels via multiscale analytical methods including scanning electronic microscopy/energy dispersive spectrometer (SEM/EDS), micro-hardness, micro-Fourier transform infrared spectroscopy (μFTIR), and histology. Our in vivo study showed that Mg implants enhanced the recruitment of bone marrow stromal stem cells (BMSCs) towards peri-implant bone tissue, which may be ascribed to the upregulation of local TGF-β1 and PDGF-BB. Besides, the in vitro study revealed that higher Mg ions was beneficial to the improvement of capability in cell adhesion and osteogenic differentiation of BMSCs. Thus, the enhancement in cell migration, cell adhesion and osteogenic differentiation of BMSCs may contribute to an improved tendon graft osteointegration in the Mg group. Our findings in this work may further facilitate clinical applications of Mg-based interference screws for enhancing tendon graft-bone junction healing in patients indicated for ACLR. How to promote tendon-bone junction healing is one of the major challenging issues for satisfactory clinical outcomes in patients after ACL reconstruction. The improvement of bony ingrowth into the tendon graft-bone interface

  19. The Stabilization of Amorphous Zopiclone in an Amorphous Solid Dispersion.

    PubMed

    Milne, Marnus; Liebenberg, Wilna; Aucamp, Marique

    2015-10-01

    Zopiclone is a poorly soluble psychotherapeutic agent. The aim of this study was to prepare and characterize an amorphous form of zopiclone as well as the characterization and performance of a stable amorphous solid dispersion. The amorphous form was prepared by the well-known method of quench-cooling of the melt. The solid dispersion was prepared by a solvent evaporation method of zopiclone, polyvinylpyrrolidone-25 (PVP-25), and methanol, followed by freeze-drying. The physico-chemical properties and stability of amorphous zopiclone and the solid dispersion was studied using differential scanning calorimetry (DSC), infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), hot-stage microscopy (HSM), X-ray diffractometry (XRD), solubility, and dissolution studies. The zopiclone amorphous solid-state form was determined to be a fragile glass; it was concluded that the stability of the amorphous form is influenced by both temperature and water. Exposure of amorphous zopiclone to moisture results in rapid transformation of the amorphous form to the crystalline dihydrated form. In comparison, the amorphous solid dispersion proved to be more stable with increased aqueous solubility.

  20. Synthesis of quenchable amorphous diamond

    DOE PAGES

    Zeng, Zhidan; Yang, Liuxiang; Zeng, Qiaoshi; ...

    2017-08-22

    Diamond owes its unique mechanical, thermal, optical, electrical, chemical, and biocompatible materials properties to its complete sp3-carbon network bonding. Crystallinity is another major controlling factor for materials properties. Although other Group-14 elements silicon and germanium have complementary crystalline and amorphous forms consisting of purely sp3 bonds, purely sp3-bonded tetrahedral amorphous carbon has not yet been obtained. In this letter, we combine high pressure and in situ laser heating techniques to convert glassy carbon into “quenchable amorphous diamond”, and recover it to ambient conditions. Our X-ray diffraction, high-resolution transmission electron microscopy and electron energy-loss spectroscopy experiments on the recovered sample andmore » computer simulations confirm its tetrahedral amorphous structure and complete sp3 bonding. This transparent quenchable amorphous diamond has, to our knowledge, the highest density among amorphous carbon materials, and shows incompressibility comparable to crystalline diamond.« less

  1. Thermal diffusivity of Al-Mg based metallic matrix composite reinforced with Al2O3 ceramic particles

    NASA Astrophysics Data System (ADS)

    Cruz-Orea, A.; Morales, J. E.; Saavedra S, R.; Carrasco, C.

    2010-03-01

    Thermal diffusivities of Al-Mg based metallic matrix composite reinforced with ceramic particles of Al2O3 are reported in this article. The samples were produced by rheocasting and the studied operational condition in this case is the shear rate: 800, 1400 and 2000 rpm. Additionally, the AlMg base alloy was tested. Measurements of thermal diffusivity were performed at room temperature by using photoacoustic technique.

  2. Hydrogenated Amorphous Silicon

    NASA Astrophysics Data System (ADS)

    Street, R. A.

    1991-08-01

    Divided roughly into two parts, the book describes the physical properties and device applications of hydrogenated amorphous silicon. The first section is concerned with the atomic and electronic structure, and covers growth defects and doping and defect reactions. The emphasis is on the optical and electronic properties that result from the disordered structure. The second part of the book describes electronic conduction, recombination, interfaces, and multilayers. The special attribute of a-Si:H which makes it useful is the ability to deposit the material inexpensively over large areas, while retaining good semiconducting properties, and the final chapter discusses various applications and devices.

  3. Compensated amorphous silicon solar cell

    DOEpatents

    Carlson, David E.

    1980-01-01

    An amorphous silicon solar cell incorporates a region of intrinsic hydrogenated amorphous silicon fabricated by a glow discharge wherein said intrinsic region is compensated by P-type dopants in an amount sufficient to reduce the space charge density of said region under illumination to about zero.

  4. Amorphous silicon ionizing particle detectors

    DOEpatents

    Street, Robert A.; Mendez, Victor P.; Kaplan, Selig N.

    1988-01-01

    Amorphous silicon ionizing particle detectors having a hydrogenated amorphous silicon (a--Si:H) thin film deposited via plasma assisted chemical vapor deposition techniques are utilized to detect the presence, position and counting of high energy ionizing particles, such as electrons, x-rays, alpha particles, beta particles and gamma radiation.

  5. Amorphous silicon ionizing particle detectors

    DOEpatents

    Street, R.A.; Mendez, V.P.; Kaplan, S.N.

    1988-11-15

    Amorphous silicon ionizing particle detectors having a hydrogenated amorphous silicon (a--Si:H) thin film deposited via plasma assisted chemical vapor deposition techniques are utilized to detect the presence, position and counting of high energy ionizing particles, such as electrons, x-rays, alpha particles, beta particles and gamma radiation. 15 figs.

  6. First-principles studies of hydrogen interaction with ultrathin Mg and Mg-based alloy films

    NASA Astrophysics Data System (ADS)

    Yoon, Mina; Weitering, Hanno H.; Zhang, Zhenyu

    2011-01-01

    The search for technologically and economically viable storage solutions for hydrogen fuel would benefit greatly from research strategies that involve systematic property tuning of potential storage materials via atomic-level modification. Here, we use first-principles density-functional theory to investigate theoretically the structural and electronic properties of ultrathin Mg films and Mg-based alloy films and their interaction with atomic hydrogen. Additional delocalized charges are distributed over the Mg films upon alloying them with 11.1% of Al or Na atoms. These extra charges contribute to enhance the hydrogen binding strength to the films. We calculated the chemical potential of hydrogen in Mg films for different dopant species and film thickness, and we included the vibrational degrees of freedom. By comparing the chemical potential with that of free hydrogen gas at finite temperature (T) and pressure (P), we construct a hydrogenation phase diagram and identify the conditions for hydrogen absorption or desorption. The formation enthalpies of metal hydrides are greatly increased in thin films, and in stark contrast to its bulk phase, the hydride state can only be stabilized at high P and T (where the chemical potential of free H2 is very high). Metal doping increases the thermodynamic stabilities of the hydride films and thus significantly helps to reduce the required pressure condition for hydrogen absorption from H2 gas. In particular, with Na alloying, hydrogen can be absorbed and/or desorbed at experimentally accessible T and P conditions.

  7. Degradation behavior of Mg-based biomaterials containing different long-period stacking ordered phases

    PubMed Central

    Peng, Qiuming; Guo, Jianxin; Fu, Hui; Cai, Xuecheng; Wang, Yanan; Liu, Baozhong; Xu, Zhigang

    2014-01-01

    Long-period stacking ordered (LPSO) phases play an essential role in the development of magnesium alloys because they have a direct effect on mechanical and corrosion properties of the alloys. The LPSO structures are mostly divided to 18R and 14H. However, to date there are no consistent opinions about their degradation properties although both of them can improve mechanical properties. Herein we have successfully obtained two LPSO phases separately in the same Mg-Dy-Zn system and comparatively investigated the effect of different LPSO phases on degradation behavior in 0.9 wt.% NaCl solution. Our results demonstrate that a fine metastable 14H-LPSO phase in grain interior is more effective to improve corrosion resistance due to the presence of a homogeneous oxidation film and rapid film remediation ability. The outstanding corrosion resistant Mg-Dy-Zn based alloys with a metastable 14H-LPSO phase, coupled with low toxicity of alloying elements, are highly desirable in the design of novel Mg-based biomaterials, opening up a new avenue in the area of bio-Mg. PMID:24401851

  8. Compensated amorphous silicon solar cell

    DOEpatents

    Devaud, Genevieve

    1983-01-01

    An amorphous silicon solar cell including an electrically conductive substrate, a layer of glow discharge deposited hydrogenated amorphous silicon over said substrate and having regions of differing conductivity with at least one region of intrinsic hydrogenated amorphous silicon. The layer of hydrogenated amorphous silicon has opposed first and second major surfaces where the first major surface contacts the electrically conductive substrate and an electrode for electrically contacting the second major surface. The intrinsic hydrogenated amorphous silicon region is deposited in a glow discharge with an atmosphere which includes not less than about 0.02 atom percent mono-atomic boron. An improved N.I.P. solar cell is disclosed using a BF.sub.3 doped intrinsic layer.

  9. Bulk amorphous materials

    SciTech Connect

    Schwarz, R.B.; Archuleta, J.I.; Sickafus, K.E.

    1998-12-01

    This is the final report for a three-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The objective of this work was to develop the competency for the synthesis of novel bulk amorphous alloys. The authors researched their synthesis methods and alloy properties, including thermal stability, mechanical, and transport properties. The project also addressed the development of vanadium-spinel alloys for structural applications in hostile environments, the measurement of elastic constants and thermal expansion in single-crystal TiAl from 300 to 750 K, the measurement of elastic constants in gallium nitride, and a study of the shock-induced martensitic transformations in NiTi alloys.

  10. Containerless processing of amorphous ceramics

    NASA Technical Reports Server (NTRS)

    Weber, J. K. Richard; Krishnan, Shankar; Schiffman, Robert A.; Nordine, Paul C.

    1990-01-01

    The absence of gravity allows containerless processing of materials which could not otherwise be processed. High melting point, hard materials such as borides, nitrides, and refractory metals are usually brittle in their crystalline form. The absence of dislocations in amorphous materials frequently endows them with flexibility and toughness. Systematic studies of the properties of many amorphous materials have not been carried out. The requirements for their production is that they can be processed in a controlled way without container interaction. Containerless processing in microgravity could permit the control necessary to produce amorphous forms of hard materials.

  11. Apatite Formation from Amorphous Calcium Phosphate and Mixed Amorphous Calcium Phosphate/Amorphous Calcium Carbonate.

    PubMed

    Ibsen, Casper J S; Chernyshov, Dmitry; Birkedal, Henrik

    2016-08-22

    Crystallization from amorphous phases is an emerging pathway for making advanced materials. Biology has made use of amorphous precursor phases for eons and used them to produce structures with remarkable properties. Herein, we show how the design of the amorphous phase greatly influences the nanocrystals formed therefrom. We investigate the transformation of mixed amorphous calcium phosphate/amorphous calcium carbonate phases into bone-like nanocrystalline apatite using in situ synchrotron X-ray diffraction and IR spectroscopy. The speciation of phosphate was controlled by pH to favor HPO4 (2-) . In a carbonate free system, the reaction produces anisotropic apatite crystallites with large aspect ratios. The first formed crystallites are highly calcium deficient and hydrogen phosphate rich, consistent with thin octacalcium phosphate (OCP)-like needles. During growth, the crystallites become increasingly stoichiometric, which indicates that the crystallites grow through addition of near-stoichiometric apatite to the OCP-like initial crystals through a process that involves either crystallite fusion/aggregation or Ostwald ripening. The mixed amorphous phases were found to be more stable against phase transformations, hence, the crystallization was inhibited. The resulting crystallites were smaller and less anisotropic. This is rationalized by the idea that a local phosphate-depletion zone formed around the growing crystal until it was surrounded by amorphous calcium carbonate, which stopped the crystallization. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Fabrication of amorphous diamond films

    DOEpatents

    Falabella, S.

    1995-12-12

    Amorphous diamond films having a significant reduction in intrinsic stress are prepared by biasing a substrate to be coated and depositing carbon ions thereon under controlled temperature conditions. 1 fig.

  13. Amorphous and Ultradisperse Crystalline Materials,

    DTIC Science & Technology

    The book sums up experimental and theoretical findings on amorphous and ultradisperse crystalline materials , massive and film types. Present-day... crystalline materials of metallic systems are presented. Emphasis is placed on inorganic film materials.

  14. Characterization Techniques for Amorphous Alloys

    NASA Astrophysics Data System (ADS)

    Carow-Watamura, U.; Louzguine, D. V.; Takeuchi, A.

    This document is part of Part 2 http://dx.doi.org/10.1007/9getType="URL"/> 'Systems from B-Be-Fe to Co-W-Zr' of Subvolume B 'Physical Properties of Ternary Amorphous Alloys' of Volume 37 'Phase Diagrams and Physical Properties of Nonequilibrium Alloys' of Landolt-Börnstein - Group III 'Condensed Matter'. It contains the Chapter '2 Characterization Techniques for Amorphous Alloys' with the content:

  15. Amorphous metal alloy and composite

    DOEpatents

    Wang, Rong; Merz, Martin D.

    1985-01-01

    Amorphous metal alloys of the iron-chromium and nickel-chromium type have excellent corrosion resistance and high temperature stability and are suitable for use as a protective coating on less corrosion resistant substrates. The alloys are stabilized in the amorphous state by one or more elements of titanium, zirconium, hafnium, niobium, tantalum, molybdenum, and tungsten. The alloy is preferably prepared by sputter deposition.

  16. Hydrogenated amorphous silicon photonics

    NASA Astrophysics Data System (ADS)

    Narayanan, Karthik

    2011-12-01

    Silicon Photonics is quickly proving to be a suitable interconnect technology for meeting the future goals of on-chip bandwidth and low power requirements. However, it is not clear how silicon photonics will be integrated into CMOS chips, particularly microprocessors. The issue of integrating photonic circuits into electronic IC fabrication processes to achieve maximum flexibility and minimum complexity and cost is an important one. In order to minimize usage of chip real estate, it will be advantageous to integrate in three-dimensions. Hydrogenated amorphous silicon (a-Si:H) is emerging as a promising material for the 3-D integration of silicon photonics for on-chip optical interconnects. In addition, a-Si:H film can be deposited using CMOS compatible low temperature plasma-enhanced chemical vapor deposition (PECVD) process at any point in the fabrication process allowing maximum flexibility and minimal complexity. In this thesis, we demonstrate a-Si:H as a high performance alternate platform to crystalline silicon, enabling backend integration of optical interconnects in a hybrid photonic-electronic network-on-chip architecture. High quality passive devices are fabricated on a low-loss a-Si:H platform enabling wavelength division multiplexing schemes. We demonstrate a broadband all-optical modulation scheme based on free-carrier absorption effect, which can enable compact electro-optic modulators in a-Si:H. Furthermore, we comprehensively characterize the optical nonlinearities in a-Si:H and observe that a-Si:H exhibits enhanced nonlinearities as compared to crystalline silicon. Based on the enhanced nonlinearities, we demonstrate low-power four-wave mixing in a-Si:H waveguides enabling high speed all-optical devices in an a-Si:H platform. Finally, we demonstrate a novel data encoding scheme using thermal and all-optical tuning of silicon waveguides, increasing the spectral efficiency in an interconnect link.

  17. Amorphous carbon for photovoltaics

    NASA Astrophysics Data System (ADS)

    Risplendi, Francesca; Grossman, Jeffrey C.

    2015-03-01

    All-carbon solar cells have attracted attention as candidates for innovative photovoltaic devices. Carbon-based materials such as graphene, carbon nanotubes (CNT) and amorphous carbon (aC) have the potential to present physical properties comparable to those of silicon-based materials with advantages such as low cost and higher thermal stability.In particular a-C structures are promising systems in which both sp2 and sp3 hybridization coordination are present in different proportions depending on the specific density, providing the possibility of tuning their optoelectronic properties and achieving comparable sunlight absorption to aSi. In this work we employ density functional theory to design suitable device architectures, such as bulk heterojunctions (BHJ) or pn junctions, consisting of a-C as the active layer material.Regarding BHJ, we study interfaces between aC and C nanostructures (such as CNT and fullerene) to relate their optoelectronic properties to the stoichiometry of aC. We demonstrate that the energy alignment between the a-C mobility edges and the occupied and unoccupied states of the CNT or C60 can be widely tuned by varying the aC density to obtain a type II interface.To employ aC in pn junctions we analyze the p- and n-type doping of a-C focusingon an evaluation of the Fermi level and work function dependence on doping.Our results highlight promising features of aC as the active layer material of thin-film solar cells.

  18. Allotropic composition of amorphous carbon

    SciTech Connect

    Yastrebov, S. G. Ivanov-Omskii, V. I.

    2007-08-15

    Using the concept of an inhomogeneous broadening of spectral lines of the basic oscillators responsible for forming the spectrum, the experimental dependences of the dispersion of the imaginary part of permittivity are analyzed for amorphous carbon. It turned out that four types of oscillators contribute to this dependence. The first three types represent the electron transitions from the energy-spectrum ground state for {pi} and {sigma} electrons of amorphous carbon to an excited state. The fourth type is related to the absorption of electromagnetic radiation by free charge carriers. The absolute values of squared plasma frequencies of oscillators are estimated, and, using them, the relative fraction of sp{sup 2}-bonded atoms forming the amorphous-carbon skeleton is calculated. This estimate agrees closely with the theoretical predictions for amorphous carbon of the same density as the material under study. The dependence of the relative fraction of sp{sup 2}-bonded atoms contained in amorphous hydrogenised carbon on annealing temperature is determined. The developed method is also applied to the analysis of the normalized curve for the light extinction in the interstellar medium. The contribution to the extinction of two varieties of interstellar matter is detected.

  19. Bulk superhard B-C-N nanocomposite compact and method for preparing thereof

    DOEpatents

    Zhao, Yusheng; He, Duanwei

    2004-07-06

    Bulk, superhard, B-C-N nanocomposite compact and method for preparing thereof. The bulk, superhard, nanocomposite compact is a well-sintered compact and includes nanocrystalline grains of at least one high-pressure phase of B-C-N surrounded by amorphous diamond-like carbon grain boundaries. The bulk compact has a Vicker's hardness of about 41-68 GPa. It is prepared by ball milling a mixture of graphite and hexagonal boron nitride, encapsulating the ball-milled mixture, and sintering the encapsulated ball-milled mixture at a pressure of about 5-25 GPa and at a temperature of about 1000-2500 K.

  20. A kinetics study on promising hydrogen storage properties of Mg-based thin films at room temperature.

    PubMed

    Qu, Jianglan; Liu, Yang; Xin, Gongbiao; Zheng, Jie; Li, Xingguo

    2014-04-21

    Pd-Mg-Pd thin films with variable thickness of Mg layers were prepared. Their optical and electrical changes in both gasochromic and chemochromic processes were compared to investigate the kinetics of Mg-based thin films at room temperature. Hydrogen absorption and desorption kinetics of Pd-Mg-Pd thin films were strongly dependent on the thickness of the Mg layer. Especially, when the thickness was lowered to 60 nm, a MgH2 layer formed immediately after exposure to H2 at room temperature, while a Mg layer was rapidly generated during hydrogen desorption in ambient air. By means of optical and electrical resistance measurements, we found that the diffusion process contributed significantly to hydrogen absorption and desorption. The remarkable absorption and desorption kinetics at room temperature reported here suggested promising applications in Mg-based energy-efficient devices and hydrogen sensors.

  1. Nanostructures having crystalline and amorphous phases

    DOEpatents

    Mao, Samuel S; Chen, Xiaobo

    2015-04-28

    The present invention includes a nanostructure, a method of making thereof, and a method of photocatalysis. In one embodiment, the nanostructure includes a crystalline phase and an amorphous phase in contact with the crystalline phase. Each of the crystalline and amorphous phases has at least one dimension on a nanometer scale. In another embodiment, the nanostructure includes a nanoparticle comprising a crystalline phase and an amorphous phase. The amorphous phase is in a selected amount. In another embodiment, the nanostructure includes crystalline titanium dioxide and amorphous titanium dioxide in contact with the crystalline titanium dioxide. Each of the crystalline and amorphous titanium dioxide has at least one dimension on a nanometer scale.

  2. Adsorption of arginine, glycine and aspartic acid on Mg and Mg-based alloy surfaces: A first-principles study

    NASA Astrophysics Data System (ADS)

    Fang, Zhe; Wang, Jianfeng; Yang, Xiaofan; Sun, Qiang; Jia, Yu; Liu, Hairong; Xi, Tingfei; Guan, Shaokang

    2017-07-01

    Studying the adsorption behaviors of biomolecules on the surface of Mg and Mg-based alloy has a fundamental and important role for related applications in biotechnology. In the present work, we systematically investigate and compare the adsorption properties of three typical amino acids, i.e., Arg (arginine), Gly (glycine) and Asp (aspartic acid), which form RGD tripeptide, on the Mg (0 0 0 1) surface with various doping (Zn, Y, and Nd), and aim to realize proper binding between biomolecules and Mg and Mg-based biomedical materials. Our results show that flat adsorption configurations of the functional groups binding to the surfaces are favored in energy for all the three selected amino acids. In specific, for the amino acids adsorped on clean Mg (0 0 0 1) surface, the adsorption energy (Eads) of Arg is found to be -1.67 eV for the most stable configuration, with amino and guanidyl groups binding with the surface. However, Gly (Asp) is found to binding with the surface through amino and carboxyl groups, with a -1.16 eV (-1.15 eV) binding energy. On the 2% Zn doped Mg (0 0 0 1) alloy surface (Mg-Zn (2%)), the Eads are significantly increased to be -1.91 eV, -1.32 eV and -1.35 eV for Arg, Gly and Asp, respectively. While the Mg-Y (1%) and Mg-Nd (1%) slightly weaken the adsorption of three amino acids. Moreover, we have performed detail discussions of the binding properties between amino acids and surfaces by projected density of states (PDOS) combined with charge transfer analyses. Our studies provide a comprehensive understanding on the interactions between amino acids and Mg and Mg-based alloy surfaces, with respect to facilitate the applications of Mg and Mg-based biomedical alloys in biosensing, drug delivery, biomolecule coating and other fields in biotechnology.

  3. Universal features of amorphous plasticity

    NASA Astrophysics Data System (ADS)

    Budrikis, Zoe; Castellanos, David Fernandez; Sandfeld, Stefan; Zaiser, Michael; Zapperi, Stefano

    2017-07-01

    Plastic yielding of amorphous solids occurs by power-law distributed deformation avalanches whose universality is still debated. Experiments and molecular dynamics simulations are hampered by limited statistical samples, and although existing stochastic models give precise exponents, they require strong assumptions about fixed deformation directions, at odds with the statistical isotropy of amorphous materials. Here, we introduce a fully tensorial, stochastic mesoscale model for amorphous plasticity that links the statistical physics of plastic yielding to engineering mechanics. It captures the complex shear patterning observed for a wide variety of deformation modes, as well as the avalanche dynamics of plastic flow. Avalanches are described by universal size exponents and scaling functions, avalanche shapes, and local stability distributions, independent of system dimensionality, boundary and loading conditions, and stress state. Our predictions consistently differ from those of mean-field depinning models, providing evidence that plastic yielding is a distinct type of critical phenomenon.

  4. Amorphous-diamond electron emitter

    DOEpatents

    Falabella, Steven

    2001-01-01

    An electron emitter comprising a textured silicon wafer overcoated with a thin (200 .ANG.) layer of nitrogen-doped, amorphous-diamond (a:D-N), which lowers the field below 20 volts/micrometer have been demonstrated using this emitter compared to uncoated or diamond coated emitters wherein the emission is at fields of nearly 60 volts/micrometer. The silicon/nitrogen-doped, amorphous-diamond (Si/a:D-N) emitter may be produced by overcoating a textured silicon wafer with amorphous-diamond (a:D) in a nitrogen atmosphere using a filtered cathodic-arc system. The enhanced performance of the Si/a:D-N emitter lowers the voltages required to the point where field-emission displays are practical. Thus, this emitter can be used, for example, in flat-panel emission displays (FEDs), and cold-cathode vacuum electronics.

  5. Generalized melting criterion for amorphization

    SciTech Connect

    Devanathan, R. |; Lam, N.Q.; Okamoto, P.R.; Meshii, M.

    1992-12-01

    We present a thermodynamic model of solid-state amorphization based on a generalization of the well-known Lindemann criterion. The original Lindemann criterion proposes that melting occurs when the root-mean-square amplitude of thermal displacement exceeds a critical value. This criterion can be generalized to include solid-state amorphization by taking into account the static displacements. In an effort to verify the generalized melting criterion, we have performed molecular dynamics simulations of radiation-induced amorphization in NiZr, NiZr{sub 2}, NiTi and FeTi using embedded-atom potentials. The average shear elastic constant G was calculated as a function of the total mean-square atomic displacement following random atom-exchanges and introduction of Frenkel pairs. Results provide strong support for the generalized melting criterion.

  6. Universal features of amorphous plasticity

    PubMed Central

    Budrikis, Zoe; Castellanos, David Fernandez; Sandfeld, Stefan; Zaiser, Michael; Zapperi, Stefano

    2017-01-01

    Plastic yielding of amorphous solids occurs by power-law distributed deformation avalanches whose universality is still debated. Experiments and molecular dynamics simulations are hampered by limited statistical samples, and although existing stochastic models give precise exponents, they require strong assumptions about fixed deformation directions, at odds with the statistical isotropy of amorphous materials. Here, we introduce a fully tensorial, stochastic mesoscale model for amorphous plasticity that links the statistical physics of plastic yielding to engineering mechanics. It captures the complex shear patterning observed for a wide variety of deformation modes, as well as the avalanche dynamics of plastic flow. Avalanches are described by universal size exponents and scaling functions, avalanche shapes, and local stability distributions, independent of system dimensionality, boundary and loading conditions, and stress state. Our predictions consistently differ from those of mean-field depinning models, providing evidence that plastic yielding is a distinct type of critical phenomenon. PMID:28671191

  7. Universal features of amorphous plasticity.

    PubMed

    Budrikis, Zoe; Castellanos, David Fernandez; Sandfeld, Stefan; Zaiser, Michael; Zapperi, Stefano

    2017-07-03

    Plastic yielding of amorphous solids occurs by power-law distributed deformation avalanches whose universality is still debated. Experiments and molecular dynamics simulations are hampered by limited statistical samples, and although existing stochastic models give precise exponents, they require strong assumptions about fixed deformation directions, at odds with the statistical isotropy of amorphous materials. Here, we introduce a fully tensorial, stochastic mesoscale model for amorphous plasticity that links the statistical physics of plastic yielding to engineering mechanics. It captures the complex shear patterning observed for a wide variety of deformation modes, as well as the avalanche dynamics of plastic flow. Avalanches are described by universal size exponents and scaling functions, avalanche shapes, and local stability distributions, independent of system dimensionality, boundary and loading conditions, and stress state. Our predictions consistently differ from those of mean-field depinning models, providing evidence that plastic yielding is a distinct type of critical phenomenon.

  8. The effect of selected alloying element additions on properties of Mg-based alloy as bioimplants: A literature review

    NASA Astrophysics Data System (ADS)

    Zhang, Li-Nan; Hou, Zeng-Tao; Ye, Xin; Xu, Zhao-Bin; Bai, Xue-Ling; Shang, Peng

    2013-09-01

    This review investigates the current application limitations of Mg and Mg alloys. The key issues hindering the application of biodegradable Mg alloys as implants are their fast degradation rate and biological consideration. We have discussed the effect of some selected alloying element additions on the properties of the Mg-based alloy, especially the nutrient elements in human (Zn, Mn, Ca, Sr). Different grain sizes, phase constituents and distributions consequently influence the mechanical properties of the Mg alloys. Solution strengthening and precipitation strengthening are enhanced by the addition of alloying elements, generally improving the mechanical properties. Besides, the hot working process can also improve the mechanical properties. Combination of different processing steps is suggested to be adopted in the fabrication of Mg-based alloys. Corrosion properties of these Mg-based alloys have been measured in vitro and in vivo. The degradation mechanism is also discussed in terms of corrosion types, rates, byproducts and response of the surrounding tissues. Moreover, the clinical response and requirements of degradable implants are presented, especially for the nutrient elements (Ca, Mn, Zn, Sr). This review provides information related to different Mg alloying elements and presents the promising candidates for an ideal implant.

  9. Degradation of trichloroethene with a noval ball milled Fe-C nanocomposite

    DOE PAGES

    Gao, Jie; Wang, Wei; Rondinone, Adam Justin; ...

    2015-07-18

    Nanoscale zero-valent iron (NZVI) is effective in reductively degrading dense non-aqueous phase liquids (DNAPLs), such as trichloroethene (TCE), in groundwater (i.e., dechlorination) although the NZVI technology itself still suffers from high material costs and inability to target hydrophobic contaminants in source zones. To address these problems, we developed a novel, inexpensive iron-carbon (Fe-C) nanocomposite material by simultaneously milling micron-size iron and activated carbon powder. Microscopic and X-ray diffraction (XRD) characterization of the composite material revealed that nanoparticles of Fe were dispersed in activated carbon and a new iron carbide phase was formed. Bench-scale studies showed that this material instantaneously sorbedmore » >90% of TCE from aqueous solutions and subsequently decomposed TCE into non-chlorinated products. Compared to milled Fe, Fe-C nanocomposite dechlorinated TCE at a slightly slower rate and favored the production of ethene over other TCE degradation products such as C3-C6 compounds. When placed in hexane-water mixture, the Fe-C nanocomposite materials are preferentially partitioned into the organic phase, indicating the ability of the composite materials to target DNAPL during remediation.« less

  10. Degradation of trichloroethene with a noval ball milled Fe-C nanocomposite

    SciTech Connect

    Gao, Jie; Wang, Wei; Rondinone, Adam Justin; He, Feng; Liang, Liyuan

    2015-07-18

    Nanoscale zero-valent iron (NZVI) is effective in reductively degrading dense non-aqueous phase liquids (DNAPLs), such as trichloroethene (TCE), in groundwater (i.e., dechlorination) although the NZVI technology itself still suffers from high material costs and inability to target hydrophobic contaminants in source zones. To address these problems, we developed a novel, inexpensive iron-carbon (Fe-C) nanocomposite material by simultaneously milling micron-size iron and activated carbon powder. Microscopic and X-ray diffraction (XRD) characterization of the composite material revealed that nanoparticles of Fe were dispersed in activated carbon and a new iron carbide phase was formed. Bench-scale studies showed that this material instantaneously sorbed >90% of TCE from aqueous solutions and subsequently decomposed TCE into non-chlorinated products. Compared to milled Fe, Fe-C nanocomposite dechlorinated TCE at a slightly slower rate and favored the production of ethene over other TCE degradation products such as C3-C6 compounds. When placed in hexane-water mixture, the Fe-C nanocomposite materials are preferentially partitioned into the organic phase, indicating the ability of the composite materials to target DNAPL during remediation.

  11. Chemical reactions of metal powders with organic and inorganic liquids during ball milling

    NASA Technical Reports Server (NTRS)

    Arias, A.

    1975-01-01

    Chromium and/or nickel powders were milled in metal chlorides and in organic liquids representative of various functional groups. The powders always reacted with the liquid and became contaminated with elements from them. The milled powders had specific surface areas ranging from 0.14 to 37 sq m/g, and the total contamination with elements from the milling liquid ranged from 0.01 to 56 weight percent. Compounds resulting from substitution, addition, or elimination reactions formed in or from the milling liquid.

  12. Optimizing particle size reduction of biochar using a planetary ball mill

    USDA-ARS?s Scientific Manuscript database

    With world demand for fossil fuels consistently growing, reducing our dependence on petroleum products is a necessary strategy. Our research group is currently studying the feasibility of biochar as rubber composite filler. If biochar can be used as a partial or complete substitute for carbon black ...

  13. Dependence of rates of breakage on fines content in wet ball mill grinding

    NASA Astrophysics Data System (ADS)

    Bhattacharyya, Anirban

    The following research fundamentally deals with the cause and implications of nonlinearities in breakage rates of materials in wet grinding systems. The innate dependence of such nonlinearities on fines content and the milling environment during wet grinding operations is also tested and observed. Preferential breakage of coarser size fractions as compared to the finer size fractions in a particle population were observed and discussed. The classification action of the pulp was deemed to be the probable cause for such a peculiarity. Ores with varying degrees of hardness and brittleness were used for wet grinding experiments, primarily to test the variations in specific breakage rates as a function of varying hardness. For this research, limestone, quartzite, and gold ore were used. The degree of hardness is of the order of: limestone, quartzite, gold ore. Selection and breakage function parameters were determined in the course of this research. Functional forms of these expressions were used to compare experimentally derived parameter estimates. Force-fitting of parameters was not done in order to examine the realtime behavior of particle populations in wet grinding systems. Breakage functions were established as being invariant with respect to such operating variables like ball load, mill speed, particle load, and particle size distribution of the mill. It was also determined that specific selection functions were inherently dependent on the particle size distribution in wet grinding systems. Also, they were consistent with inputs of specific energy, according to grind time. Nonlinearity trends were observed for 1st order specific selection functions which illustrated variations in breakage rates with incremental inputs of grind time and specific energy. A mean particle size called the fulcrum was noted below which the nonlinearities in the breakage trends were observed. This magnitude of the fulcrum value varied with percent solids and slurry filling, indicating that breakage rates were being influenced by the milling environment as a whole. Primarily, there was always an increase in the breakage rates of coarser fractions with an increase in the amount of fines in the particle population. Consequently, the breakage rates of the finer size fractions were observed to decrease with an increase in grind time. Similar trends were noticed for 2nd order specific selection functions, where incremental inputs of specific energy were provided to observe realtime trends in the nonlinearity of breakage rates closely. Although the breakage rates for coarser size fractions increase with an increase in the amount of fines, the nature of nonlinearities varied with extended grind times. 1st order and 2nd order energy-specific breakage rates were observed to notice the variation in trends with extended grind times. Implications of such nonlinearities in specific breakage rates of various materials were tested on predictive simulation techniques, using the normalized linear population balance model and compared with an incremental methodology of specific energy input.

  14. Synthesis and Characterization of Aluminum-Nanodiamond Composite Powders by High Energy Ball Milling

    DTIC Science & Technology

    2011-12-01

    Niobium , milled at the same parameters developed only 4.03 wt% Fe contamination [10]. The weight of the milling media to the powder, also known...111> ND peak was illustrated because due to the small size of the ND particles and grains, the higher order peaks signals are too weak for such...REFERENCES [1] J. Montgomery, et al, “Low-cost titanium armors for combat vehicles,” JOM, vol. 49, no. 5, pp. 45–47, 1997. [2] M. Myers and K. Chawla

  15. Corrosion behavior of magnesium powder fabricated by high-energy ball milling and spark plasma sintering

    NASA Astrophysics Data System (ADS)

    Kim, Ka Ram; Ahn, Jin Woo; Kim, Gyeung-Ho; Han, Jun Hyun; Cho, Kwon Koo; Roh, Jae-Seung; Kim, Woo Jin; Kim, Hye Sung

    2014-11-01

    Microstructural changes and corrosion behavior of pure magnesium for different milling times were investigated. The samples with a finer grain size showed poor corrosion resistance because of unstable or metastable protective film formation after immersion in 0.8 wt% NaCl solution. The corrosion resistance did not improve despite the strong (0002) texture of the sample prepared by spark plasma sintering at 500 °C for 0.3 Ks and milling for 2 h. By studying the microstructural changes and texture development, we concluded that the deformation-dependent grain size is the dominant factor controlling the corrosion properties of mechanically milled magnesium. Increased grain boundary densities lead to an enhancement of the overall surface reactivity and, consequently, the corrosion rate.

  16. Effects of ball milling parameters on microstructural evolution and mechanical properties of W-3% Y composites

    NASA Astrophysics Data System (ADS)

    Zhao, Mingyue; Zhou, Zhangjian; Tan, Jun; Ding, Qingming; Zhong, Ming

    2015-10-01

    The W-3 Y composites were successfully prepared by spark plasma sintering of milled W-3 Y powders with different milling times (0 h, 5 h, 15 h, 30 h). X-ray diffraction (XRD), scanning electron microscope (SEM), and laser particle size analysis were used to study the microstructural evolution and morphological change during the milling process. The crystallite sizes exhibited a continuous refinement along with the increased milling time. The median particle sizes, measured by the laser diffraction method, showed a similar change tendency. Due to the existence of Y particles, the W-Y milled powders exhibited spherical-like morphology while pure tungsten milled powders exhibited lamellar morphology at the early milling stage (5-15 h). The microhardness of W-3 Y compacts showed a slight increase with the increase of milling time. The maximum bending strength of 795 MPa was obtained by sintering W-3 Y powders milled for 15 h. As the milling time was prolonged to 30 h, the increased oxygen impurity resulted in a slight decrease of density as well as the degradation of bending strength.

  17. Studies on copper-yttria nanocomposites: high-energy ball milling versus chemical reduction method.

    PubMed

    Joshi, P B; Rehani, Bharati; Naik, Palak; Patel, Swati; Khanna, P K

    2012-03-01

    Oxide dispersion-strengthened copper-base composites are widely used for applications demanding high tensile strength, high hardness along with good electrical and thermal conductivity. Oxides of metals like aluminium, cerium, yttrium and zirconium are often used for this purpose as fine and uniformly distributed dispersoid particles in soft and ductile copper matrix. Such composites find applications as electrical contacts, resistance-welding tips, lead wires, continuous casting moulds, etc. In this investigation an attempt has been made to produce copper-yttria nanocomposites using two different morphologies of copper powder and two different processing routes namely, high-energy milling and in-situ chemical reduction. The synthesized powders were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) for their phase identification and morphological study. The nanocomposite powders in each case were subsequently processed to obtain bulk solids by classical powder metallurgy route of press-sinter-repress. The resultant bulk solid compacts were subjected to property evaluation. The study revealed that the properties of Cu-Y2O3 nanocomposites depend on the processing route used and in turn on the resultant powder morphology.

  18. Magnetism and structure of Fe Cu binary solid solutions obtained by high-energy ball milling

    NASA Astrophysics Data System (ADS)

    Gorria, P.; Martínez-Blanco, D.; Blanco, J. A.; Pérez, M. J.; González, M. A.; Campo, J.

    2006-10-01

    Martensitic phase transformation is found in various metals, alloys, ceramics and even biological systems. This paper reports on the Fe segregated anomalous α- γ martensitic transformation observed in Fe xCu 100-x binary solid solutions ( x=25 and 50) after subsequent heating-cooling processes. A characteristic observable feature of a martensitic transformation is the microstructure it produces, thermal hysteresis, evolution and metastability. We have analysed the microstructure using neutron thermo-diffraction experiments up to 1100 K. The structural changes of the Fe segregated phase, from bcc to fcc crystal structures, have been followed in detail. The most relevant feature is that the onset of martensite transformation is observed, on heating, more than 100 K below the expected temperature for pure bcc-Fe (1183 K), while the reverse transformation occurs below 900 K on cooling. This anomalous behaviour for the α- γ transformation depends on sample composition, being more important for low Fe contents. Besides that, magnetisation vs. temperature measurements show a clear correlation with structure changes, thus exhibiting thermal hysteresis on heating-cooling cycles. Moreover, a magnetisation enhancement above 550 K is observed on heating, this fact can be attributed to thermal-induced ferromagnetism on isolated γ-Fe precipitates via strong magneto-volume coupling.

  19. Synthesis of Binary Nanocrystalline Aluminum Alloys through High Energy Ball Milling

    NASA Astrophysics Data System (ADS)

    Schwab, Lacey L.

    Nanocrystalline metals have useful mechanical properties such as high strength, improved wear resistance, and longer fatigue life; however, they are relatively unstable--grain boundary doping is a viable method towards stabilization [1-3]. After comparing the work of Murdoch and Schuh, that used a thermodynamic model to estimate grain boundary segregation enthalpy to the experimental work of Umbrajkar et al., it was realized that mechanical alloying is a processing route for grain boundary stabilization [10,11]. Whether or not chemical mixing has occurred is a good indicator of a powder system's potential for grain boundary doping. 99Al1Si, 99Al1Mg, 99Al1Zr, and 99Al11Zn were mechanically alloyed with a Retch 100 Planetary Bal Mill. The samples were then analyzed with a Rigaku Ultima III X-ray Diffractometer to determine whether or not these powder systems have chemically mixed. It was found that the 99Al1Mg powder system chemically mixed during the 8Hr, 8mL run and during the 16Hr, 16.5mL run, and the 99Al1Zr powder system chemically mixed during the 4Hr, 16.5mL run. The enthalpy of segregation values for each binary powder system correlated to the chemical mixing shown in these results.

  20. Warming up for mechanosynthesis - temperature development in ball mills during synthesis.

    PubMed

    Kulla, Hannes; Wilke, Manuel; Fischer, Franziska; Röllig, Mathias; Maierhofer, Christiane; Emmerling, Franziska

    2017-02-04

    We present a first direct measurement of the temperature during milling combined with in situ Raman spectroscopy monitoring. The data reveal a low temperature increase due to the mechanical impact and clear temperature increases as a consequence of the reaction heat. Based on the data, temperature rises as postulated in the magma plasma and hot spot theory can be excluded for soft matter milling syntheses.

  1. Evolution of in Fe-doped manganites synthesized by the ball-milling method

    NASA Astrophysics Data System (ADS)

    Cherif, W.; Alonso, J. A.; Elhalouani, F.

    2017-01-01

    Manganites-based perovskites, having the general formula Ln0.67A0.33Mn1- x M x O3 where Ln is a rare earth element (Ln = Pr, La, ldots) and A is an alkaline earth element (A = Sr, Ba, Ca, ldots), were the center of interest of many studies because of their outstanding physicochemical properties and because they can play an important role in various applications. The aim of this work is the development with mechanical alloying method and study of physicochemical properties of new manganites. This work focuses on the development and characterization of series La0.67Ca0.11Sr0.22Mn1- x Fe x O3 ( 0≤ x≤ 0.3. The structural study showed that the cell parameters of the samples increase with the increase in the rate of iron and causing the expansion of the orthorhombic distortion. This result is confirmed by the tolerance factor tg (0.75 < tg < 0.95: orthorhombic structure). The magnetic study showed that the substitution of Mn by Fe in these series indicates a ferromagnetic-paramagnetic transition. This transition accompanied with a decrease in the Curie temperature (T_C).

  2. A Mössbauer effect study of ball-milled strontium ferrite

    NASA Astrophysics Data System (ADS)

    Wu, E.; Campbell, S. J.; Kaczmarek, W. A.

    1998-01-01

    The effects of milling SrFe 12O 19 in air and vacuum for 800 h have been investigated by X-ray diffraction and Mössbauer effect spectroscopy measurements. Different levels of structural disorder along with partial decomposition of SrFe 12O 19 to nanocrystalline grains of haematite, α-Fe 2O 3, and magnetite, Fe 3O 4, are obtained for the air and vacuum milling. Superparamagnetic relaxation effects due to the fine particles produced on milling are observed for a significant fraction ( ˜ 10% air milled, ˜ 30% vacuum milled) of the milled samples.

  3. Structural, magnetic and electrical properties of the lithium ferrite obtained by ball milling and heat treatment

    NASA Astrophysics Data System (ADS)

    Mazen, S. A.; Abu-Elsaad, N. I.

    2015-01-01

    The physical properties of ferrites are very sensitive to microstructure, which in turn critically depends on the manufacturing process. Lithium ferrite is synthesized by milling process. The powder was annealed at four different temperatures 600, 800, 1,000 and 1,200 °C. The powder annealed at 600 °C has the spinel structure with some of α-Fe2O3, while the powders annealed at ≥800 °C formed in single-phase cubic spinel structure. Particle size of lithium ferrite is in the range of 26-70 nm, and is dependent on the annealing temperature. The saturation magnetization increased from 22 to 85 emu/g and the coercivity decreases from 124 to 4 Oe with increase in the annealing temperature. The dielectric constant ( ɛ'), dielectric loss (tan δ) and ac conductivity ( σ ac) were measured at room temperature as a function of frequency. The results of dielectric properties were explained in terms of Koops phenomenological theory.

  4. Ultrastable Amorphous Sb2Se3 Film.

    PubMed

    Zhang, Kai; Li, Yang; Huang, Quan; Wang, Bihan; Zheng, Xuerong; Ren, Yang; Yang, Wenge

    2017-08-31

    Increasing the thermostability of amorphous materials has been a long journey to improve their properties. The metastable nature of chalcogenide glasses limits their practical applications as an amorphous semiconductor in photovoltaic performance. Here, we report the formation and physical properties of ultrastable amorphous Sb2Se3 with an enhanced thermal stability compared to ordinary amorphous Sb2Se3 (ΔTx= 17 K). By in situ high temperature-high energy synchrotron X-ray diffraction, the difference in structure relaxation between ordinary and ultrastable amorphous Sb2Se3 was manifested by local structure evolution. Ultrastable amorphous Sb2Se3 showed the smallest surface roughness and highest refractive index, the mechanism behind was further discussed in terms of fast molecular mobility and molecular orientation during vapor deposition. Formation of ultrastable amorphous Sb2Se3 demonstrated a promising avenue to obtain novel functional amorphous semiconductor with modulated structure and property.

  5. Imprinting bulk amorphous alloy at room temperature

    SciTech Connect

    Kim, Song-Yi; Park, Eun-Soo; Ott, Ryan T.; Lograsso, Thomas A.; Huh, Moo-Young; Kim, Do-Hyang; Eckert, Jürgen; Lee, Min-Ha

    2015-11-13

    We present investigations on the plastic deformation behavior of a brittle bulk amorphous alloy by simple uniaxial compressive loading at room temperature. A patterning is possible by cold-plastic forming of the typically brittle Hf-based bulk amorphous alloy through controlling homogenous flow without the need for thermal energy or shaping at elevated temperatures. The experimental evidence suggests that there is an inconsistency between macroscopic plasticity and deformability of an amorphous alloy. Moreover, imprinting of specific geometrical features on Cu foil and Zr-based metallic glass is represented by using the patterned bulk amorphous alloy as a die. These results demonstrate the ability of amorphous alloys or metallic glasses to precisely replicate patterning features onto both conventional metals and the other amorphous alloys. In conclusion, our work presents an avenue for avoiding the embrittlement of amorphous alloys associated with thermoplastic forming and yields new insight the forming application of bulk amorphous alloys at room temperature without using heat treatment.

  6. Imprinting bulk amorphous alloy at room temperature

    PubMed Central

    Kim, Song-Yi; Park, Eun-Soo; Ott, Ryan T.; Lograsso, Thomas A.; Huh, Moo-Young; Kim, Do-Hyang; Eckert, Jürgen; Lee, Min-Ha

    2015-01-01

    We present investigations on the plastic deformation behavior of a brittle bulk amorphous alloy by simple uniaxial compressive loading at room temperature. A patterning is possible by cold-plastic forming of the typically brittle Hf-based bulk amorphous alloy through controlling homogenous flow without the need for thermal energy or shaping at elevated temperatures. The experimental evidence suggests that there is an inconsistency between macroscopic plasticity and deformability of an amorphous alloy. Moreover, imprinting of specific geometrical features on Cu foil and Zr-based metallic glass is represented by using the patterned bulk amorphous alloy as a die. These results demonstrate the ability of amorphous alloys or metallic glasses to precisely replicate patterning features onto both conventional metals and the other amorphous alloys. Our work presents an avenue for avoiding the embrittlement of amorphous alloys associated with thermoplastic forming and yields new insight the forming application of bulk amorphous alloys at room temperature without using heat treatment. PMID:26563908

  7. Amorphous rare earth magnet powders

    SciTech Connect

    Sellers, C.H.; Branagan, D.J.; Hyde, T.A.; Lewis, L.H.; Panchanathan, V.

    1996-08-01

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

  8. Amorphous titanium-oxide supercapacitors

    NASA Astrophysics Data System (ADS)

    Fukuhara, Mikio; Kuroda, Tomoyuki; Hasegawa, Fumihiko

    2016-10-01

    The electric capacitance of an amorphous TiO2-x surface increases proportionally to the negative sixth power of the convex diameter d. This occurs because of the van der Waals attraction on the amorphous surface of up to 7 mF/cm2, accompanied by extreme enhanced electron trapping resulting from both the quantum-size effect and an offset effect from positive charges at oxygen-vacancy sites. Here we show that a supercapacitor, constructed with a distributed constant-equipment circuit of large resistance and small capacitance on the amorphous TiO2-x surface, illuminated a red LED for 37 ms after it was charged with 1 mA at 10 V. The fabricated device showed no dielectric breakdown up to 1,100 V. Based on this approach, further advances in the development of amorphous titanium-dioxide supercapacitors might be attained by integrating oxide ribbons with a micro-electro mechanical system.

  9. Model for amorphous aggregation processes

    NASA Astrophysics Data System (ADS)

    Stranks, Samuel D.; Ecroyd, Heath; van Sluyter, Steven; Waters, Elizabeth J.; Carver, John A.; von Smekal, Lorenz

    2009-11-01

    The amorphous aggregation of proteins is associated with many phenomena, ranging from the formation of protein wine haze to the development of cataract in the eye lens and the precipitation of recombinant proteins during their expression and purification. While much literature exists describing models for linear protein aggregation, such as amyloid fibril formation, there are few reports of models which address amorphous aggregation. Here, we propose a model to describe the amorphous aggregation of proteins which is also more widely applicable to other situations where a similar process occurs, such as in the formation of colloids and nanoclusters. As first applications of the model, we have tested it against experimental turbidimetry data of three proteins relevant to the wine industry and biochemistry, namely, thaumatin, a thaumatinlike protein, and α -lactalbumin. The model is very robust and describes amorphous experimental data to a high degree of accuracy. Details about the aggregation process, such as shape parameters of the aggregates and rate constants, can also be extracted.

  10. Optical absorption in amorphous silicon

    SciTech Connect

    O`Leary, S.K.; Zukotynski, S.; Perz, J.M.; Sidhu, L.S.

    1996-12-31

    The role that disorder plays in shaping the form of the optical absorption spectrum of hydrogenated amorphous silicon is investigated. Disorder leads to a redistribution of states, which both reduces the Tauc gap and broadens the absorption tail. The observed relationship between the Tauc gap and the breadth of the absorption tail is thus explained.

  11. Amorphous titanium-oxide supercapacitors

    PubMed Central

    Fukuhara, Mikio; Kuroda, Tomoyuki; Hasegawa, Fumihiko

    2016-01-01

    The electric capacitance of an amorphous TiO2-x surface increases proportionally to the negative sixth power of the convex diameter d. This occurs because of the van der Waals attraction on the amorphous surface of up to 7 mF/cm2, accompanied by extreme enhanced electron trapping resulting from both the quantum-size effect and an offset effect from positive charges at oxygen-vacancy sites. Here we show that a supercapacitor, constructed with a distributed constant-equipment circuit of large resistance and small capacitance on the amorphous TiO2-x surface, illuminated a red LED for 37 ms after it was charged with 1 mA at 10 V. The fabricated device showed no dielectric breakdown up to 1,100 V. Based on this approach, further advances in the development of amorphous titanium-dioxide supercapacitors might be attained by integrating oxide ribbons with a micro-electro mechanical system. PMID:27767103

  12. Flexible amorphous metal films with high stability

    NASA Astrophysics Data System (ADS)

    Liu, M.; Cao, C. R.; Lu, Y. M.; Wang, W. H.; Bai, H. Y.

    2017-01-01

    We report the formation of amorphous Cu50Zr50 films with a large-area of more than 100 cm2. The films were fabricated by ion beam assisted deposition with a slow deposition rate at moderate temperature. The amorphous films have markedly enhanced thermal stability, excellent flexibility, and high reflectivity with atomic level smoothness. The multifunctional properties of the amorphous films are favorites in the promising applications of smart skin or wearable devices. The method of preparing highly stable amorphous metal films by tuning the deposition rate instead of deposition temperature could pave a way for exploring amorphous metal films with unique properties.

  13. New horizon for high performance Mg-based biomaterial with uniform degradation behavior: Formation of stacking faults

    NASA Astrophysics Data System (ADS)

    Zhang, Jinghuai; Xu, Chi; Jing, Yongbin; Lv, Shuhui; Liu, Shujuan; Fang, Daqing; Zhuang, Jinpeng; Zhang, Milin; Wu, Ruizhi

    2015-09-01

    Designing the new microstructure is an effective way to accelerate the biomedical application of magnesium (Mg) alloys. In this study, a novel Mg-8Er-1Zn alloy with profuse nano-spaced basal plane stacking faults (SFs) was prepared by combined processes of direct-chill semi-continuous casting, heat-treatment and hot-extrusion. The formation of SFs made the alloy possess outstanding comprehensive performance as the biodegradable implant material. The ultimate tensile strength (UTS: 318 MPa), tensile yield strength (TYS: 207 MPa) and elongation (21%) of the alloy with SFs were superior to those of most reported degradable Mg-based alloys. This new alloy showed acceptable biotoxicity and degradation rate (0.34 mm/year), and the latter could be further slowed down through optimizing the microstructure. Most amazing of all, the uniquely uniform in vitro/vivo corrosion behavior was obtained due to the formation of SFs. Accordingly we proposed an original corrosion mechanism for the novel Mg alloy with SFs. The present study opens a new horizon for developing new Mg-based biomaterials with highly desirable performances.

  14. New horizon for high performance Mg-based biomaterial with uniform degradation behavior: Formation of stacking faults

    PubMed Central

    Zhang, Jinghuai; Xu, Chi; Jing, Yongbin; Lv, Shuhui; Liu, Shujuan; Fang, Daqing; Zhuang, Jinpeng; Zhang, Milin; Wu, Ruizhi

    2015-01-01

    Designing the new microstructure is an effective way to accelerate the biomedical application of magnesium (Mg) alloys. In this study, a novel Mg–8Er–1Zn alloy with profuse nano-spaced basal plane stacking faults (SFs) was prepared by combined processes of direct-chill semi-continuous casting, heat-treatment and hot-extrusion. The formation of SFs made the alloy possess outstanding comprehensive performance as the biodegradable implant material. The ultimate tensile strength (UTS: 318 MPa), tensile yield strength (TYS: 207 MPa) and elongation (21%) of the alloy with SFs were superior to those of most reported degradable Mg-based alloys. This new alloy showed acceptable biotoxicity and degradation rate (0.34 mm/year), and the latter could be further slowed down through optimizing the microstructure. Most amazing of all, the uniquely uniform in vitro/vivo corrosion behavior was obtained due to the formation of SFs. Accordingly we proposed an original corrosion mechanism for the novel Mg alloy with SFs. The present study opens a new horizon for developing new Mg-based biomaterials with highly desirable performances. PMID:26349676

  15. Topological Insulators in Amorphous Systems

    NASA Astrophysics Data System (ADS)

    Agarwala, Adhip; Shenoy, Vijay B.

    2017-06-01

    Much of the current understanding of topological insulators, which informs the experimental search for topological materials and systems, is based on crystalline band theory, where local electronic degrees of freedom at different crystal sites hybridize with each other in ways that produce nontrivial topology. Here we provide a novel theoretical demonstration of realizing topological phases in amorphous systems, as exemplified by a set of sites randomly located in space. We show this by constructing hopping models on such random lattices whose gapped ground states are shown to possess nontrivial topological nature (characterized by Bott indices) that manifests as quantized conductances in systems with a boundary. Our study adds a new dimension, beyond crystalline solids, to the search for topological systems by pointing to the promising possibilities in amorphous solids and other engineered random systems.

  16. Topological Insulators in Amorphous Systems.

    PubMed

    Agarwala, Adhip; Shenoy, Vijay B

    2017-06-09

    Much of the current understanding of topological insulators, which informs the experimental search for topological materials and systems, is based on crystalline band theory, where local electronic degrees of freedom at different crystal sites hybridize with each other in ways that produce nontrivial topology. Here we provide a novel theoretical demonstration of realizing topological phases in amorphous systems, as exemplified by a set of sites randomly located in space. We show this by constructing hopping models on such random lattices whose gapped ground states are shown to possess nontrivial topological nature (characterized by Bott indices) that manifests as quantized conductances in systems with a boundary. Our study adds a new dimension, beyond crystalline solids, to the search for topological systems by pointing to the promising possibilities in amorphous solids and other engineered random systems.

  17. Comparison of Mg-based multilayers for solar He II radiation at 30.4 nm wavelength

    SciTech Connect

    Zhu Jingtao; Zhou Sika; Li Haochuan; Huang Qiushi; Wang Zhanshan; Le Guen, Karine; Hu, Min-Hui; Andre, Jean-Michel; Jonnard, Philippe

    2010-07-10

    Mg-based multilayers, including SiC/Mg, Co/Mg, B4C/Mg, and Si/Mg, are investigated for solar imaging and a He II calibration lamp at a 30.4 nm wavelength. These multilayers were fabricated by a magnetron sputtering method and characterized by x-ray reflection. The reflectivities of these multilayers were measured by synchrotron radiation. Near-normal-incidence reflectivities of Co/Mg and SiC/Mg multilayer mirrors are as high as 40.3% and 44.6%, respectively, while those of B4C/Mg and Si/Mg mirrors are too low for application. The measured results suggest that SiC/Mg, Co/Mg multilayers are promising for a 30.4 nm wavelength.

  18. On Structure and Properties of Amorphous Materials

    PubMed Central

    Stachurski, Zbigniew H.

    2011-01-01

    Mechanical, optical, magnetic and electronic properties of amorphous materials hold great promise towards current and emergent technologies. We distinguish at least four categories of amorphous (glassy) materials: (i) metallic; (ii) thin films; (iii) organic and inorganic thermoplastics; and (iv) amorphous permanent networks. Some fundamental questions about the atomic arrangements remain unresolved. This paper focuses on the models of atomic arrangements in amorphous materials. The earliest ideas of Bernal on the structure of liquids were followed by experiments and computer models for the packing of spheres. Modern approach is to carry out computer simulations with prediction that can be tested by experiments. A geometrical concept of an ideal amorphous solid is presented as a novel contribution to the understanding of atomic arrangements in amorphous solids. PMID:28824158

  19. Narrow band gap amorphous silicon semiconductors

    DOEpatents

    Madan, A.; Mahan, A.H.

    1985-01-10

    Disclosed is a narrow band gap amorphous silicon semiconductor comprising an alloy of amorphous silicon and a band gap narrowing element selected from the group consisting of Sn, Ge, and Pb, with an electron donor dopant selected from the group consisting of P, As, Sb, Bi and N. The process for producing the narrow band gap amorphous silicon semiconductor comprises the steps of forming an alloy comprising amorphous silicon and at least one of the aforesaid band gap narrowing elements in amount sufficient to narrow the band gap of the silicon semiconductor alloy below that of amorphous silicon, and also utilizing sufficient amounts of the aforesaid electron donor dopant to maintain the amorphous silicon alloy as an n-type semiconductor.

  20. Amorphous silicon solar cell allowing infrared transmission

    DOEpatents

    Carlson, David E.

    1979-01-01

    An amorphous silicon solar cell with a layer of high index of refraction material or a series of layers having high and low indices of refraction material deposited upon a transparent substrate to reflect light of energies greater than the bandgap energy of the amorphous silicon back into the solar cell and transmit solar radiation having an energy less than the bandgap energy of the amorphous silicon.

  1. Amorphous-Amorphous Phase Separation in API/Polymer Formulations.

    PubMed

    Luebbert, Christian; Huxoll, Fabian; Sadowski, Gabriele

    2017-02-15

    The long-term stability of pharmaceutical formulations of poorly-soluble drugs in polymers determines their bioavailability and therapeutic applicability. However, these formulations do not only often tend to crystallize during storage, but also tend to undergo unwanted amorphous-amorphous phase separations (APS). Whereas the crystallization behavior of APIs in polymers has been measured and modeled during the last years, the APS phenomenon is still poorly understood. In this study, the crystallization behavior, APS, and glass-transition temperatures formulations of ibuprofen and felodipine in polymeric PLGA excipients exhibiting different ratios of lactic acid and glycolic acid monomers in the PLGA chain were investigated by means of hot-stage microscopy and DSC. APS and recrystallization was observed in ibuprofen/PLGA formulations, while only recrystallization occurred in felodipine/PLGA formulations. Based on a successful modeling of the crystallization behavior using the Perturbed-Chain Statistical Associating Fluid Theory (PC-SAFT), the occurrence of APS was predicted in agreement with experimental findings.

  2. The physics and applications of amorphous semiconductors

    SciTech Connect

    Madan, A.; Shaw, M.P.

    1988-01-01

    This is a treatise on the physics and applications of the new emerging technology of amorphous semiconductors. The authors focus upon research problems such as the optimization of device performance while also presenting the general physics of amorphous semiconductors. The first part of the book covers hydrogenated amorphous silicon type alloys, whose applications include inexpensive solar cells, thin film transistors, image scanners, electrophotography, optical recording, and gas sensors. The second part of the book discusses amorphous chalcogenides, whose applications include electrophotography, switching, and memory elements.

  3. Amorphous silicon based radiation detectors

    SciTech Connect

    Perez-Mendez, V.; Cho, G.; Drewery, J.; Jing, T.; Kaplan, S.N.; Qureshi, S.; Wildermuth, D. ); Fujieda, I.; Street, R.A. )

    1991-07-01

    We describe the characteristics of thin(1 {mu}m) and thick (>30{mu}m) hydrogenated amorphous silicon p-i-n diodes which are optimized for detecting and recording the spatial distribution of charged particles, x-rays and {gamma} rays. For x-ray, {gamma} ray, and charged particle detection we can use thin p-i-n photosensitive diode arrays coupled to evaporated layers of suitable scintillators. For direct detection of charged particles with high resistance to radiation damage, we use the thick p-i-n diode arrays. 13 refs., 7 figs.

  4. Preparation of amorphous sulfide sieves

    DOEpatents

    Siadati, Mohammad H.; Alonso, Gabriel; Chianelli, Russell R.

    2006-11-07

    The present invention involves methods and compositions for synthesizing catalysts/porous materials. In some embodiments, the resulting materials are amorphous sulfide sieves that can be mass-produced for a variety of uses. In some embodiments, methods of the invention concern any suitable precursor (such as thiomolybdate salt) that is exposed to a high pressure pre-compaction, if need be. For instance, in some cases the final bulk shape (but highly porous) may be same as the original bulk shape. The compacted/uncompacted precursor is then subjected to an open-flow hot isostatic pressing, which causes the precursor to decompose and convert to a highly porous material/catalyst.

  5. Structural study of amorphous polyaniline

    NASA Astrophysics Data System (ADS)

    Laridjani, M.; Pouget, J. P.; MacDiarmid, A. G.; Epstein, A. J.

    1992-06-01

    Many materials, especially polymers, have a substantial volume fraction with no long range crystalline order. Through these regions are often termed amorphous, they frequently have a specific local order. We describe and use here a method, base on a non-energy dispersive X-ray diffraction technique, to obtain good quality interference functions and, by Fourier transform, radial distribution functions of the amorphous structure of polymers. We apply this approach to members of a family of electronic polymers of current interest : polyaniline emeraldine bases. We show that the local order exhibits significant differences in type I and type II materials, precipitated as salt and base respectively. These studies demonstrate the importance of sample preparation in evaluating the physical properties of polyaniline, and provide a structural origin for memory effects observed in the doping-dedoping processes. Beaucoup de matériaux, spécialement les polymères, ont une importante fraction de leur volume sans ordre cristallin à longue portée. Bien que ces régions soient souvent appelées amorphes, elles présentent fréquemment un ordre local caractéristique. Nous décrivons et utilisons dans ce papier une méthode, basée sur une technique de diffraction de rayons X non dispersive en énergie, pour obtenir des fonctions d'interférence de bonne qualité et, par transformée de Fourier, la fonction de distribution radiale des polymères amorphes. Nous appliquons cette technique à plusieurs éléments d'une même famille de polymères électroniques d'intérêt actuel : les polyanilines éméraldine bases. Nous montrons que l'ordre local présente d'appréciables différences dans les matériaux de type I et II, préparés respectivement sous forme de sel et de base. Cette étude démontre l'importance des conditions de préparation sur les propriétés physiques du polyaniline et donne une base structurale aux effets observés dans les processus de dopage-dédopage de

  6. Is Mg-stabilized amorphous calcium carbonate a homogeneous mixture of amorphous magnesium carbonate and amorphous calcium carbonate?

    PubMed

    Yang, Sheng-Yu; Chang, Hsun-Hui; Lin, Cang-Jie; Huang, Shing-Jong; Chan, Jerry C C

    2016-10-04

    We find two types of carbonate ions in Mg stabilized amorphous calcium carbonate (Mg-ACC), whose short-range orders are identical to those of ACC and amorphous magnesium carbonate (AMC). Mg-ACC comprises a homogeneous mixture of the nano-clusters of ACC and AMC. Their relative amount varies systematically at different pH.

  7. Laser surface treatment of amorphous metals

    NASA Astrophysics Data System (ADS)

    Katakam, Shravana K.

    Amorphous materials are used as soft magnetic materials and also as surface coatings to improve the surface properties. Furthermore, the nanocrystalline materials derived from their amorphous precursors show superior soft magnetic properties than amorphous counter parts for transformer core applications. In the present work, laser based processing of amorphous materials will be presented. Conventionally, the nanocrystalline materials are synthesized by furnace heat treatment of amorphous precursors. Fe-based amorphous/nanocrystalline materials due to their low cost and superior magnetic properties are the most widely used soft magnetic materials. However, achieving nanocrystalline microstructure in Fe-Si-B ternary system becomes very difficult owing its rapid growth rate at higher temperatures and sluggish diffusion at low temperature annealing. Hence, nanocrystallization in this system is achieved by using alloying additions (Cu and Nb) in the ternary Fe-Si-B system. Thus, increasing the cost and also resulting in reduction of saturation magnetization. laser processing technique is used to achieve extremely fine nanocrystalline microstructure in Fe-Si-B amorphous precursor. Microstructure-magnetic Property-laser processing co-relationship has been established for Fe-Si-B ternary system using analytical techniques. Laser processing improved the magnetic properties with significant increase in saturation magnetization and near zero coercivity values. Amorphous materials exhibit excellent corrosion resistance by virtue of their atomic structure. Fe-based amorphous materials are economical and due to their ease of processing are of potential interest to synthesize as coatings materials for wear and corrosion resistance applications. Fe-Cr-Mo-Y-C-B amorphous system was used to develop thick coatings on 4130 Steel substrate and the corrosion resistance of the amorphous coatings was improved. It is also shown that the mode of corrosion depends on the laser processing

  8. Fluorination of amorphous thin-film materials with xenon fluoride

    DOEpatents

    Weil, R.B.

    1987-05-01

    A method is disclosed for producing fluorine-containing amorphous semiconductor material, preferably comprising amorphous silicon. The method includes depositing amorphous thin-film material onto a substrate while introducing xenon fluoride during the film deposition process.

  9. Fluorination of amorphous thin-film materials with xenon fluoride

    DOEpatents

    Weil, Raoul B.

    1988-01-01

    A method is disclosed for producing fluorine-containing amorphous semiconductor material, preferably comprising amorphous silicon. The method includes depositing amorphous thin-film material onto a substrate while introducing xenon fluoride during the film deposition process.

  10. Imprinting bulk amorphous alloy at room temperature

    DOE PAGES

    Kim, Song-Yi; Park, Eun-Soo; Ott, Ryan T.; ...

    2015-11-13

    We present investigations on the plastic deformation behavior of a brittle bulk amorphous alloy by simple uniaxial compressive loading at room temperature. A patterning is possible by cold-plastic forming of the typically brittle Hf-based bulk amorphous alloy through controlling homogenous flow without the need for thermal energy or shaping at elevated temperatures. The experimental evidence suggests that there is an inconsistency between macroscopic plasticity and deformability of an amorphous alloy. Moreover, imprinting of specific geometrical features on Cu foil and Zr-based metallic glass is represented by using the patterned bulk amorphous alloy as a die. These results demonstrate the abilitymore » of amorphous alloys or metallic glasses to precisely replicate patterning features onto both conventional metals and the other amorphous alloys. In conclusion, our work presents an avenue for avoiding the embrittlement of amorphous alloys associated with thermoplastic forming and yields new insight the forming application of bulk amorphous alloys at room temperature without using heat treatment.« less

  11. Amorphization of solids irradiated by fast neutrons

    NASA Astrophysics Data System (ADS)

    Parkhomenko, V.; Dubinin, S.; Teploukhov, S.; Goshchitskii, B.

    2000-03-01

    The diffraction patterns of amorphous solids produced by both a conventional technique and fast neutron irradiation were systematized. It is shown for the first time that neutron radiation-modified solids belong to the group of amorphous substances of a distortion type.

  12. Evolution of the structure of amorphous ice: from low-density amorphous through high-density amorphous to very high-density amorphous ice.

    PubMed

    Martonák, R; Donadio, D; Parrinello, M

    2005-04-01

    We report results of molecular dynamics simulations of amorphous ice for pressures up to 22.5 kbar. The high-density amorphous ice (HDA) as prepared by pressure-induced amorphization of I(h) ice at T=80 K is annealed to T=170 K at various pressures to allow for relaxation. Upon increase of pressure, relaxed amorphous ice undergoes a pronounced change of structure, ranging from the low-density amorphous ice at p=0, through a continuum of HDA states to the limiting very high-density amorphous ice (VHDA) regime above 10 kbar. The main part of the overall structural change takes place within the HDA megabasin, which includes a variety of structures with quite different local and medium-range order as well as network topology and spans a broad range of densities. The VHDA represents the limit to densification by adapting the hydrogen-bonded network topology, without creating interpenetrating networks. The connection between structure and metastability of various forms upon decompression and heating is studied and discussed. We also discuss the analogy with amorphous and crystalline silica. Finally, some conclusions concerning the relation between amorphous ice and supercooled water are drawn.

  13. Electron beam recrystallization of amorphous semiconductor materials

    NASA Technical Reports Server (NTRS)

    Evans, J. C., Jr.

    1968-01-01

    Nucleation and growth of crystalline films of silicon, germanium, and cadmium sulfide on substrates of plastic and glass were investigated. Amorphous films of germanium, silicon, and cadmium sulfide on amorphous substrates of glass and plastic were converted to the crystalline condition by electron bombardment.

  14. Electron tunnelling into amorphous germanium and silicon.

    NASA Technical Reports Server (NTRS)

    Smith, C. W.; Clark, A. H.

    1972-01-01

    Measurements of tunnel conductance versus bias, capacitance versus bias, and internal photoemission were made in the systems aluminum-oxide-amorphous germanium and aluminium-oxide-amorphous silicon. A function was extracted which expresses the deviation of these systems from the aluminium-oxide-aluminium system.

  15. Method of making amorphous metal composites

    DOEpatents

    Byrne, Martin A.; Lupinski, John H.

    1982-01-01

    The process comprises placing an amorphous metal in particulate form and a low molecular weight (e.g., 1000-5000) thermosetting polymer binder powder into a container, mixing these materials, and applying heat and pressure to convert the mixture into an amorphous metal composite.

  16. Co amorphous systems: A product development perspective.

    PubMed

    Chavan, Rahul B; Thipparaboina, Rajesh; Kumar, Dinesh; Shastri, Nalini R

    2016-12-30

    Solubility is one of the major problems associated with most of the new chemical entities that can be reasonably addressed by drug amorphization. However, being a high-energy form, it usually tends to re-crystallize, necessitating new formulation strategies to stabilize amorphous drugs. Polymeric amorphous solid dispersion (PASD) is one of the widely investigated strategies to stabilize amorphous drug, with major limitations like limited polymer solubility and hygroscopicity. Co amorphous system (CAM), a new entrant in amorphous arena is a promising alternative to PASD. CAMs are multi component single phase amorphous solid systems made up of two or more small molecules that may be a combination of drugs or drug and excipients. Excipients explored for CAM preparation include amino acids, carboxylic acids, nicotinamide and saccharine. Advantages offered by CAM include improved aqueous solubility and physical stability of amorphous drug, with a potential to improve therapeutic efficacy. This review attempts to address different aspects in the development of CAM as drug products. Criterion for co-former selection, various methods involved in CAM preparation, characterization tools, stability, scale up and regulatory requirements for the CAM product development are discussed.

  17. Density Functional Theory Study of Hydrogen Adsorption in a Ti-Decorated Mg-Based Metal-Organic Framework-74.

    PubMed

    Suksaengrat, Pitphichaya; Amornkitbamrung, Vittaya; Srepusharawoot, Pornjuk; Ahuja, Rajeev

    2016-03-16

    The Ti-binding energy and hydrogen adsorption energy of a Ti-decorated Mg-based metal-organic framework-74 (Mg-MOF-74) were evaluated by using first-principles calculations. Our results revealed that only three Ti adsorption sites were found to be stable. The adsorption site near the metal oxide unit is the most stable. To investigate the hydrogen-adsorption properties of Ti-functionalized Mg-MOF-74, the hydrogen-binding energy was determined. For the most stable Ti adsorption site, we found that the hydrogen adsorption energy ranged from 0.26 to 0.48 eV H2 (-1) . This is within the desirable range for practical hydrogen-storage applications. Moreover, the hydrogen capacity was determined by using ab initio molecular dynamics simulations. Our results revealed that the hydrogen uptake by Ti-decorated Mg-MOF-74 at temperatures of 77, 150, and 298 K and ambient pressure were 1.81, 1.74, and 1.29 H2  wt %, respectively. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Neutron irradiation induced amorphization of silicon carbide

    SciTech Connect

    Snead, L.L.; Hay, J.C.

    1998-09-01

    This paper provides the first known observation of silicon carbide fully amorphized under neutron irradiation. Both high purity single crystal hcp and high purity, highly faulted (cubic) chemically vapor deposited (CVD) SiC were irradiated at approximately 60 C to a total fast neutron fluence of 2.6 {times} 10{sup 25} n/m{sup 2}. Amorphization was seen in both materials, as evidenced by TEM, electron diffraction, and x-ray diffraction techniques. Physical properties for the amorphized single crystal material are reported including large changes in density ({minus}10.8%), elastic modulus as measured using a nanoindentation technique ({minus}45%), hardness as measured by nanoindentation ({minus}45%), and standard Vickers hardness ({minus}24%). Similar property changes are observed for the critical temperature for amorphization at this neutron dose and flux, above which amorphization is not possible, is estimated to be greater than 130 C.

  19. Structure, thermodynamics, and crystallization of amorphous hafnia

    SciTech Connect

    Luo, Xuhui; Demkov, Alexander A.

    2015-09-28

    We investigate theoretically amorphous hafnia using the first principles melt and quench method. We identify two types of amorphous structures of hafnia. Type I and type II are related to tetragonal and monoclinic hafnia, respectively. We find type II structure to show stronger disorder than type I. Using the phonon density of states, we calculate the specific heat capacity for type II amorphous hafnia. Using the nudged elastic band method, we show that the averaged transition barrier between the type II amorphous hafnia and monoclinic phase is approximately 0.09 eV/HfO{sub 2}. The crystallization temperature is estimated to be 421 K. The calculations suggest an explanation for the low thermal stability of amorphous hafnia.

  20. Amorphization of sugar hydrates upon milling.

    PubMed

    Willart, J F; Dujardin, N; Dudognon, E; Danède, F; Descamps, M

    2010-07-19

    The possibility to amorphize anhydrous crystalline sugars, like lactose, trehalose and glucose, by mechanical milling was previously reported. We test here the possibility to amorphize the corresponding crystalline hydrates: lactose monohydrate, trehalose dihydrate and glucose monohydrate using fully identical milling procedures. The results show that only the first hydrate amorphizes while the other two remain structurally invariant. These different behaviours are attributed to the plasticizing effect of the structural water molecules which can decrease the glass transition temperature below the milling temperature. The results reveal clearly the fundamental role of the glass transition in the solid-state amorphization process induced by milling, and they also explain why crystalline hydrates are systematically more difficult to amorphize by milling than their anhydrous counterpart. The investigations have been performed by differential scanning calorimetry and powder X-ray diffraction.