References of "Boschini, Frédéric"
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See detailHighly efficient doped nanocristalline TiO2 for water Treatment
Mahy, Julien ULg; Léonard, Géraldine ULg; Zubiaur, Anthony ULg et al

Conference (2017, July 13)

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See detailOne-step hydrothermal synthesis and electrochemical performance of sodium-manganese-iron phosphate as cathode material for Li-ion batteries
Karegeya, Claude ULg; Mahmoud, Abdelfattah ULg; Vertruyen, Bénédicte ULg et al

in Journal of Solid State Chemistry (2017), 253

The sodium-manganese-iron phosphate Na2Mn1.5Fe1.5(PO4)3 (NMFP) with alluaudite structure was obtained by a one-step hydrothermal synthesis route. The physical properties and structure of this material ... [more ▼]

The sodium-manganese-iron phosphate Na2Mn1.5Fe1.5(PO4)3 (NMFP) with alluaudite structure was obtained by a one-step hydrothermal synthesis route. The physical properties and structure of this material were obtained through XRD and Mössbauer analyses. X-ray diffraction Rietveld refinements confirm a cationic distribution of Na+ and presence of vacancies in A(2)’, Na+ and small amounts of Mn2+ in A(1), Mn2+ in M(1) , 0.5 Mn2+ and Fe cations (Mn2+,Fe2+ and Fe3+) in M(2), leading to the structural formula Na2Mn(Mn0.5Fe1.5)(PO4)3. The particles morphology was investigated by SEM. Several reactions with different hydrothermal reaction times were attempted to design a suitable synthesis protocol of NMFP compound. The time of reaction was varied from 6 to 48 hours at 220°C. The pure phase of NMFP particles was firstly obtained when the hydrothermal reaction of NMFP precursors mixture was maintained at 220°C for 6 hours. When the reaction time was increased from 6 to 12, 24 and 48 hours, the dandelion structure was destroyed in favor of NMFP micro-rods. The combination of NMFP (NMFP-6H, NMFP-12H, NMFP-24H and NMFP-48H) structure refinement and Mössbauer characterizations shows that the increase of the reaction time leads to the progressive increment of Fe(III) and the decrease of the crystal size. The electrochemical tests indicated that NMFP is a 3 V sodium intercalating cathode. The comparison of the discharge capacity evolution of studied NMFP electrode materials at C/5 current density shows different capacities of 48, 40, 34 and 34 mAhg-1 for NMFP-6H, NMFP-12H, NMFP-24H and NMFP-48H respectively. Interestingly, all samples show excellent capacity retention of about 99 % during 50 cycles. [less ▲]

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See detailExperimental design helps to optimize spray drying processes
Dellicour, Aline ULg; Cloots, Rudi ULg; Boschini, Frédéric ULg

Poster (2017, June)

Experimental design is necessary to identify major experimental parameters linked to a process in order to optimize it and reduce costs. It also helps to reduce the number of experiments and analyze data ... [more ▼]

Experimental design is necessary to identify major experimental parameters linked to a process in order to optimize it and reduce costs. It also helps to reduce the number of experiments and analyze data statistically. This work aims to present some possibilities of how experimental design may be applied in the field of pharmaceutical powders production by spray drying. Depending on the application, powders need particular size, morphology, purity, crystallinity or polymorphism. All these characteristics may be influenced by process parameters and should be controlled to reach pharmaceutical requirements. [less ▲]

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See detailStructural and Magnetic Properties of Nanosized strontium Hexaferrite Powders: Experimental and theoretical investigation
Abraime, Brahim; Ait Tamerd, Mohamed; Mahmoud, Abdelfattah ULg et al

Poster (2017, May 18)

Strontium M-type hexagonal ferrites were synthesized at different calcination temperatures (800 °C, 1000°C and 1100 °C) using sol-gel autocombustion method. Thermogravimetric analysis (TGA), X-ray ... [more ▼]

Strontium M-type hexagonal ferrites were synthesized at different calcination temperatures (800 °C, 1000°C and 1100 °C) using sol-gel autocombustion method. Thermogravimetric analysis (TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM), Mössbauer spectroscopy (MS) and superconducting quantum interference device magnetometer (SQUID) techniques were used to characterize crystal structure, phase composition, morphology and magnetic properties. TGA gives T=800 °C as beginning of suitable calcination. Hexaferrite structure of single phase is obtained according to XRD results for all samples with crystallite size between 28 nm and 35 nm. SEM images show the growth of grain size with increasing of annealing temperature. (BH)max is calculated based on SQUID results and shows an enhancement between T=800°C and T= 1000°C of 25%. The magnetic properties observed at low temperature are explained and confirmed by ab-initio calculations. [less ▲]

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See detailAn easy route to synthesis black phosphorus at low pressure and soft conditions
Tiouitchi, Ghassane; Hamedoun, Mohammed; El Kenz, Abdallah et al

Conference (2017, May 11)

Black phosphorus a promising candidate for large application, due to his variety of structural and physical properties, can be prepared by a very low-coast reaction route with high purity and ... [more ▼]

Black phosphorus a promising candidate for large application, due to his variety of structural and physical properties, can be prepared by a very low-coast reaction route with high purity and crystallinity. Black phosphorus is prepared from red phosphorus at 873K under reduced pressure using a simple and low cost catalytic system. The quality of crystal with lattice parameters a=3.31Å, b=10.48Å, c=4.37Å can be approved by a series of characterizations like scanning microscopy electron (SEM), energy dispersive spectrometry (EDX), Raman spectroscopy and powder X-rays. The new preparation method of black phosphorus represents an easy, effective and low cost approach to avoid complicated preparative setups, toxic catalysts, or “dirty” flux methods and is of general interest in elemental chemistry. [less ▲]

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See detailEnergy product and magnetic properties of strontium hexagonal ferrite: experimental and theoretical investigation
Abraime, Brahim; Ait Tamerd, Mohamed; Mahmoud, Abdelfattah ULg et al

Conference (2017, May 10)

The interest toward hard magnetic materials increases in the last years. In order to have the best magnetic properties of these materials, researchers count on the efficiency of different synthesis ... [more ▼]

The interest toward hard magnetic materials increases in the last years. In order to have the best magnetic properties of these materials, researchers count on the efficiency of different synthesis methods. In permanent magnets application, ferrite materials possess a good place among the other magnet families. In permanent magnets field, the more important parameter that describes the magnetic strength of a magnet is the maximum energy product (BH)max. A strong permanent magnet has an important value of (BH)max. In this work, we will study the effect of annealing temperature on maximum energy product and other magnetic properties of Strontium hexaferrite SrFe12O19 synthesized using sol-gel autocombustion method, with different annealing temperatures, characterized using Thermogravimetric analysis (TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM), Mössbauer spectroscopy (MS) and superconducting quantum interference device magnetometer (SQUID). Ab initio calculation for magnetic properties is also performed in order to compare it with low temperature experimental results. [less ▲]

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See detailSpray Drying-­Assisted Synthesis of Na2FePO4F/CB and Na2FePO4F/CNT Composite Cathodes for Lithium Ion Battery
Mahmoud, Abdelfattah ULg; Brisbois; Caes, sebastien et al

Conference (2017, May 08)

Fluorophosphates are considered among the most interesting series of cathode materials for Li/Na-ion batteries. Na2FePO4F, with layered structure and two-dimensional pathways for facile Na+/Li+ transport ... [more ▼]

Fluorophosphates are considered among the most interesting series of cathode materials for Li/Na-ion batteries. Na2FePO4F, with layered structure and two-dimensional pathways for facile Na+/Li+ transport [1], exhibits minimal structural changes (3.7%) upon reduction/oxidation. The average working voltage is 3.3 V versus Li+/Li. However, one of the key drawbacks of Na2FePO4F electrodes is their low intrinsic electronic conductivity. In this work, we report on the synthesis of Na2FePO4F by spray-drying, a technique which is easily scaled-up from the lab- to the industrial-scale and ensures a good homogeneity of all precursors. We are investigating the replacement of the grinding step by the addition of conductive carbon (carbon black and carbon nanotubes) to the solution containing the inorganic precursors of the Na2FePO4F phase in order to prepare Na2FePO4F/CB and Na2FePO4F/CNT with different ratios of CB and CNT (10 and 20%) and enhanced conductivity. The electrochemical performance shows that the addition of CNT improves remarkably the capacity of the NFPF electrode material thanks to better CNT dispersion inside and at the surface of the NFPF particles which enhances the electronic conductivity. Acknowledgements: The authors thank the Walloon Region for support under the “PE Plan Marshall 2.vert” program (BATWAL -1318146). A. Mahmoud is grateful to the Walloon region for a Beware Fellowship Academia 2015-1, RESIBAT n° 1510399. References [1] M. Brisbois, S. Caes, M-T. Sougrati, B. Vertruyen, A. Schrijnemakers, R. Cloots, N. Eshraghi, R-P. Hermann, A. Mahmoud, F. Boschini, Solar Energy Materials & Solar Cells 148 (2015) 11-19. [less ▲]

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See detailMagnetocaloric Properties of Zinc-Nickel Ferrites Around Room Temperature
El Maalam, Khadija; Fkhar, lahcen; Mohammed, Hamedoun et al

in Journal of Superconductivity and Novel Magnetism (2017)

In this paper, structural, magnetic, and magnetocaloric properties of zinc-doped nickel ferrite, Zn1−xNixFe2O4 (x = 0.3 and 0.4) were investigated. The samples were prepared using solid-state reaction. X ... [more ▼]

In this paper, structural, magnetic, and magnetocaloric properties of zinc-doped nickel ferrite, Zn1−xNixFe2O4 (x = 0.3 and 0.4) were investigated. The samples were prepared using solid-state reaction. X-ray diffraction (XRD) and magnetization measurements were performed to study crystallographic structure and magnetic properties. For a magnetic field changing from 0 to 5 T, the corresponding isothermal entropy change was found to be near 1.4 J/kg K for both samples. The decreasing of Ni content from x = 0.4 to 0.3, enables to shift the Curie temperature of Zn1−xNixFe2O4 from 450 K toward (325 K). As main results, it was found that the relative cooling power (RCP) could be significantly enhanced by changing Ni concentration in Zn1−xNixFe2O4 (505 J/kg (for x = 0.3) and 670 J/kg (for x = 0.4)), which is considered as a recommended parameter for a wide temperature range in magnetic refrigeration application. Our finding should inspire and open new ways for the enhancement of the magnetocaloric effect in spinel ferrite-based materials. [less ▲]

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See detailSodium vanadium (III) fluorophosphate/carbon nanotubes composite (NVPF/CNT) prepared by spray-drying: good electrochemical performance thanks to well-dispersed CNT network within NVPF particles
Eshraghi, Nicolas ULg; Caes, Sebastien; Mahmoud, Abdelfattah ULg et al

in Electrochimica Acta (2017), 228

We successfully prepared NASICON-type Na3V2(PO4)2F3 (NVPF) and a Na3V2(PO4)2F3/carbon nanotubes (CNT) composite by spray-drying followed by heat treatment in argon for 2 hours at 600 °C. The addition of ... [more ▼]

We successfully prepared NASICON-type Na3V2(PO4)2F3 (NVPF) and a Na3V2(PO4)2F3/carbon nanotubes (CNT) composite by spray-drying followed by heat treatment in argon for 2 hours at 600 °C. The addition of CNT in the spray-drying solution creates a CNT network within the NVPF particles. After grinding, the smaller NVPF particles remain linked by CNT. Thanks to this conducting network, the composite powder displays competitive electrochemical performance when cycled against lithium in hybrid-ion batteries (2–4.6 V vs. Li+/Li) with specific capacities of 125 mAh.g−1 at C/10, 103 mAh.g−1 at 1C and 91 mAh.g−1 at 4C, together with 97.5% capacity retention at 1C over 100 cycles with coulombic efficiency of 99.4%. These results demonstrate that sodium vanadium (III) fluorophosphate electrode material can be obtained in a time-efficient way using the easily up-scalable spray-drying method. [less ▲]

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See detailHydrothermal synthesis of tailored new  promising phosphate particles for lithium and sodium ion batteries
Karegeya, Claude ULg; Mahmoud, Abdelfattah ULg; Sougrati Tahar, Moulay et al

Conference (2016, December 16)

The rechargeable Li-ion batteries dominate the currently used storage systems due to their unrivalled electrochemical properties. However, this technology needs more improvements to meet coast, high ... [more ▼]

The rechargeable Li-ion batteries dominate the currently used storage systems due to their unrivalled electrochemical properties. However, this technology needs more improvements to meet coast, high capacity, safety and environmental requirements. Current researches on Li-ion batteries are focusing on the development of safe and cheap electrode compounds with good electrochemical performance. Iron phosphate-based electrodes have attracted increasing interest due to their environmental compatibility, low cost and its promising electrochemical performance as positive electrode materials in LIB. In this work, we report the electrochemical properties of Fex(PO4)(OH)y.zH2O) cathode material obtained by one-pot hydrothermal synthesis route, a technique which produces the particles with suitable properties for electrode application. We show that the addition of a conducting carbon (carbon black or carbon nanotubes) into the solution has a strong influence on reducing the size and tailoring morphology of material particles. These are among the main factors to enhance the electrochemical performance of the material. Combined with electrochemical and XRD studies, operando Mössbauer analysis shows that Fex(PO4)(OH)y.zH2O) undergoes a reversible reduction/oxidation during lithium intercalation/ deintercalation processes. Acknowledgments This work was supported by the Walloon Region through the BATWAL project [PE Plan Marshall 2.vert]; and the Beware Fellowship Academia [2015-1, RESIBAT n° 1510399]. [less ▲]

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See detailMOSSBAUER SPECTROSCOPY AS A COMPLEMENTARY TECHNIQUE OF X-RAY DIFFRACTION TO INVESTIGATE ELECTRODE MATERIALS FOR ALKALI-ION BATTERIES
Mahmoud, Abdelfattah ULg; sougrati, Moulay Tahar; karegeya, claude et al

Poster (2016, October 09)

Lithium-ion batteries (LIBs) have been widely applied as a power source for portable electronics, stationary energy storage systems, and electric vehicles. Nevertheless, as lithium resources continue to ... [more ▼]

Lithium-ion batteries (LIBs) have been widely applied as a power source for portable electronics, stationary energy storage systems, and electric vehicles. Nevertheless, as lithium resources continue to decline worldwide and Li in the Earth’s crust is unevenly distributed as minor-metal. Na-ion batteries are considered to be an alternative to Li-ion batteries owing to the natural abundance of sodium. Indeed, Sodium-ion (Na-ion) batteries are expected to become part of the mix of technologies that will meet the challenges of energy storage. Electrode materials are the most important components in the operation and the performances of Alkali-ion batteries. New electrode materials are required to increase the energy density of Li/Na-ion batteries [1]. Fe based negative electrode materials for Li-ion batteries have been previously investigated to evaluate the electrochemical performances and elucidate the electrochemical reaction mechanisms. Mössbauer spectroscopy has been applied to a variety of fields including chemistry, physics, geology, biology…. In the domain of energy storage, Mössbauer spectroscopy has been used as a powerful tool to investigate the local electronic and structural properties of electrode materials and to determine their reaction mechanisms during charge and discharge of Li/Na-ion batteries [2]. In this poster, we will show from some selected examples how Mössbauer spectroscopy when used with X-ray diffraction can help to improve the performances of electrode materials for Alkali-ion batteries. References 1. Sougrati MT, Darwiche A, Liu X, Mahmoud A, Hermann RP, Jouen S, Monconduit L, Dronskowski R, Stievano L: Transition-metal carbodiimides as molecular negative electrode materials for lithium- and sodium-ion batteries with excellent cycling properties. Angew Chem Int Ed., 2016, 55: 5090-5095. 2. Brisbois, M., Caes, S., Sougrati, M. T., Vertruyen, B., Schrijnemakers, A., Cloots, R., Eshraghi, N., Hermann, R. P., Mahmoud, A., Boschini, F. Na2FePO4F/Multi-Walled Carbon Nanotubes for Lithium-Ion Batteries_ Operando Mössbauer Study of Spray- Dried Composites. Solar Energy Materials and Solar Cells 2016, 148, 67–72. Acknowledgment A. Mahmoud and F. Boschini would like to kindly thank Wallonie regions for the financial support. [less ▲]

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See detailTowards a large scale aqueous sol-gel synthesis of doped TiO2: Study of various metallic dopings for the photocatalytic degradation of p-nitrophenol
Mahy, Julien ULg; Lambert, Stéphanie ULg; Léonard, Géraldine ULg et al

in Journal of Photochemistry and Photobiology A : Chemistry (2016), 329

In this paper, an easy aqueous sol-gel synthesis developed previously by Mahy et al. [J. Sol-Gel Sci. Technol. (2016)] is adapted to produce highly active TiO2 catalysts doped with Fe3+, Ag+, Cu2+, Zn2 ... [more ▼]

In this paper, an easy aqueous sol-gel synthesis developed previously by Mahy et al. [J. Sol-Gel Sci. Technol. (2016)] is adapted to produce highly active TiO2 catalysts doped with Fe3+, Ag+, Cu2+, Zn2+, Cr3+, Al3+, Mn2+, and Co2+ ions and Pt metallic nanoparticles. Samples are characterized by inductively coupled plasma–atomic emission spectroscopy (ICP-AES), X-ray diffraction (XRD), Mössbauer spectroscopy, transmission electron microscopy (TEM), nitrogen adsorption–desorption measurements and diffuse reflectance spectroscopy measurements. Results show that the samples are composed of anatase-brookite TiO2 nanoparticles with a spherical shape and mean diameter of around 5-8 nm and a surface area of between about 150 - 250 m2 g-1. In each doped sample, the dopant is present in the form added during the synthesis, given that the sample has not undergone any particular treatment. Photoactivity tests show improvement in catalyst activity for Fe3+, Ag+, Cu2+, Zn2+, and Al3+ ion and Pt metallic nanoparticle dopants, while a decrease of activity is obtained for Cr3+, Mn2+ and Co2+ ion dopants. For some dopants, the activity of TiO2 doped with metallic ions and synthesized from the aqueous sol-gel process is equal or superior to the activity of the commercial photocatalyst Degussa P25. Some mechanisms are proposed to explain these modifications of activity with doping. Furthermore, cost comparison at laboratory scale showed that Zn and Cu nitrate salt dopings are clearly less expensive for a halogen light (UV/visible) or low energy light enhanced catalyst and may be considered for industrial applications. Using this method, a large scale Zn-doped TiO2 photocatalyst is synthesized with properties homologous to the lab-scale product. Results show that the aqueous sol-gel synthesis developed previously can be easily adapted for doping in order to produce an up-scalable synthesis. [less ▲]

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See detailPhosphate-based composite electrodes for Li/Na-ion batteries: upscalable solution syntheses with in-situ solid carbon addition
Vertruyen, Bénédicte ULg; Brisbois, Magali; Eshraghi, Nicolas ULg et al

Conference (2016, September 22)

Since the success story of lithium iron phosphate, other phosphate-based compounds have attracted a lot of interest as promising candidates for positive electrodes in lithium-ion or sodium-ion batteries ... [more ▼]

Since the success story of lithium iron phosphate, other phosphate-based compounds have attracted a lot of interest as promising candidates for positive electrodes in lithium-ion or sodium-ion batteries. Their electronic conductivity usually has to be improved through the preparation of composite powders ensuring intimate contact between the active material and conductive carbon. We report on the one-step synthesis of composite precursors using spray-drying or hydrothermal synthesis routes, two techniques which offer easy scaling-up of production. We show that addition of a solid carbon source (carbon black or carbon nanotubes) into the solution has a strong influence on the powder microstructure and is very effective in improving the battery cycling performance, taking our recent results on phosphates [Fex(PO4)(OH)y.zH2O)] and fluorophosphates [Na2FePO4F, Na3V2(PO4)2F3] as examples. We also compare this approach with the addition of the carbon source as a soluble precursor (such as ascorbic acid or citric acid) where the in situ formation of carbon is achieved by a heat treatment in inert atmosphere (typically argon). [less ▲]

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See detailStudy of Sn and Fe based electrode materials for Alkali-ion batteries by in situ Mössbauer spectroscopy
Mahmoud, Abdelfattah ULg; Sougrati, Moulay Tahar; Hermann, Raphaël ULg et al

Conference (2016, July 19)

Li-ion batteries are widely used for electrochemical energy storage, because of their high energy density and efficiency. The most significant challenges in the development of advanced Li-ion batteries ... [more ▼]

Li-ion batteries are widely used for electrochemical energy storage, because of their high energy density and efficiency. The most significant challenges in the development of advanced Li-ion batteries concern the electrode materials. Indeed, the electrodes properties critically determine the capacity, performance, and durability of alkali-ion batteries. In the past five decades, Mössbauer spectroscopy has been an important analytical technique for investigating the structural, magnetic and electronic properties of energy materials. Mössbauer spectroscopy allows simultaneous investigation of bulk and surface characteristics. It is a non-destructive technique that can follow the behavior of electrode materials during the reaction process in situ and operando [1]. Its high resolution enables the observation of all Mössbauer active phases and the measure of their relative quantities . Iron and tin containing materials are of considerable interest as electrode material for Li-ion batteries [2, 3]. In this presentation, we report in situ and operando measurements of new electrode materials based on Fe and Sn during electrochemical cycling by combining Mössbauer spectroscopy with complementary techniques (X-ray diffraction, magnetic measurements, impedance spectroscopy, etc.) to study and investigate the electrochemical behavior of the electrode materials. [less ▲]

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See detailNa2FePO4F/multi-walled carbon nanotubes for lithium-ion batteries: Operando Mössbauer study of spray-dried composites
Brisbois, Magali; Caes, Sébastien ULg; Sougrati, M.T. et al

in Solar Energy Materials & Solar Cells (2016), 148

In order to favor electronic conductivity in sodium iron fluorophosphate electrodes for lithium- or sodium-ion batteries, composites of Na2FePO4F with multi-walled carbon nanotubes (CNTs) were prepared by ... [more ▼]

In order to favor electronic conductivity in sodium iron fluorophosphate electrodes for lithium- or sodium-ion batteries, composites of Na2FePO4F with multi-walled carbon nanotubes (CNTs) were prepared by pilot-scale spray drying. Addition of multi-walled CNTs in the solution results in an excellent dispersion of the CNTs within the volume of Na2FePO4F and not only at the surface of the particles. Following a heat treatment at 600°C in argon in order to reach crystallization, X-ray diffraction and ex situ Mössbauer spectroscopy revealed the presence of significant amounts of Fe(III) and maghemite (γ-Fe2O3) in the powder. However, Na2FePO4F/CNTs composites exhibit good electrochemical performance when cycling against lithium, with a discharge capacity of 104mAhg-1 at C/10 rate and 90mAhg-1 at 1C rate. Therefore, operando 57Fe transmission Mössbauer spectroscopy analyses were carried out in order to investigate the evolution of the iron oxidation state during cycling. During the first discharge, all the Fe(III) is reduced to Fe(II), explaining the good electrochemical performance. [less ▲]

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See detailLi4Ti5O12 powders by spray-drying: influence of the solution concentration and particle size on the electrochemical properties
Jamin, Claire; Brisbois, Magali; Caes, Sébastien ULg et al

Conference (2015, June 23)

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See detailRheological behavior of β-Ti and NiTi powders produced by atomization for SLM production of open porous orthopedic implants
Yablokova, G.; Speirs, M.; Van Humbeeck, J. et al

in Powder Technology (2015)

The growing interest for Selective Laser Melting (SLM) in orthopedic implant manufacturing is accompanied by the introduction of novel Ti alloys, in particular β-Ti for their excellent corrosion ... [more ▼]

The growing interest for Selective Laser Melting (SLM) in orthopedic implant manufacturing is accompanied by the introduction of novel Ti alloys, in particular β-Ti for their excellent corrosion resistance as well as favorable combination of high mechanical strength, fatigue resistance and relatively low elastic modulus. As part of the SLM process for producing quality β-Ti parts powder flowability is essential to achieve uniform thickness of powder layers. In this work the flowability of different gas atomized β-Ti, including NiTi, powders has been studied. Their rheological properties were compared to those of commercially available plasma-atomized Ti–6Al–4V powder using a newly developed semi-automatic experimental set-up. Not only the particle size, shape and size distribution of the powders display a large influence on the powder flowability but also particle surface properties such as roughness, chemical composition and the presence of liquid on the surface of the particles. It was found that plasma or gas atomization production techniques for SLM powder have a considerable effect on the particle topography. Among the powders studied regarding SLM applicability only rheological properties of the fine size fraction (25–45 μm) of Ti–45Nb didn't conform to SLM processing requirements. To improve flowability of the Ti–45Nb powder itwas annealed both in air and argon atmosphere at 600 °C during 1 h, resulting in an improved rheological behavior suitable for SLM processing. [less ▲]

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