Fabrication Using High-Energy Ball-Milling Technique and Characterization of Pt-Co Electrocatalysts for Oxygen Reduction in Polymer Electrolyte Fuel Cells

2005 ◽  
Vol 2 (3) ◽  
pp. 171-178 ◽  
Author(s):  
Pallavi Pharkya ◽  
Akram Alfantazi ◽  
Zoheir Farhat
Keyword(s):  
Electron Microscopy ◽  
Fuel Cells ◽  
Oxygen Reduction ◽  
Polymer Electrolyte ◽  
Ball Milling ◽  
High Energy ◽  
X Ray ◽  
Energy Ball ◽  
Ball Milling Technique

This work discusses the fabrication and characterization of Pt-Co electrocatalysts for polymer electrolyte membrane fuel cells (PEMFC) and electrocatalysis of the oxygen reduction reaction. Two sets of carbon supported catalysts with Pt:Co in the atomic ratio of 0.25:0.75 and 0.75:0.25 were prepared using a high-energy ball-milling technique. One of the Pt-Co electrocatalysts was subjected to lixiviation to examine the change in surface area. Microstructural characterization of the electrocatalysts was done using scanning electron microscopy, transmission electron microscopy, x-ray diffractometry, and x-ray photoelectron spectroscopy. Electrochemical characterization of the electrocatalysts was done in acidic and alkaline media using cyclic voltammetry and potentiodynamic polarization techniques. These tests were performed at room and higher temperature (50°C). Performances of the electrocatalysts were also compared with the commercial E-TEK Pt:Co alloy electrocatalysts of the compositions 10% Pt-Co alloy (1:1 a/o) and 40% Pt-Co alloy (1:1 a/o) on Vulcan XC-72.

Synthesis and Characterization of Al-Alloy/SiCp Nanocomposites Employing High Energy Ball Milling and Spark Plasma Sintering

2011 ◽  
Vol 410 ◽  
pp. 224-227 ◽  
Author(s):  
Sivaiah Bathula ◽  
R.C. Anandani ◽  
Ajay Dhar ◽  
A.K. Srivastava
Keyword(s):  
Electron Microscopy ◽  
Ball Milling ◽  
High Energy ◽  
Synthesis And Characterization ◽  
Al Alloy ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Energy Ball ◽  
Nanocomposite Powders

This study reports the synthesis and characterization of Al-alloy/SiCpmetal matrix nanocomposite, synthesized using high energy ball milling followed by sintering employing spark plasma sintering (SPS). In the present investigation, Al 5083 alloy powder (15 μm) and 10wt.% SiC particulates (~20 nm) were milled in a high-energy planetary ball mill to produce nanocrystalline Al-alloy/SiC nanocomposite powders. X-ray diffraction analysis (XRD) was carried out for milled and un-milled powder and it was observed that, as the time of milling increased, the crystallite size of Al-alloy matrix decreased sharply. The average crystallite size of Al-matrix from XRD analysis was observed to be ~ 25 nm after 15 h of ball milling. Ball milled nanocomposite powders were consolidated and sintered employing SPS at a temperature range of 500°C with a heating rate of 300°C/min and the total sintering cycle was completed in 8 min. The mechanical properties were found to substantially increase after sintering employing SPS. Morphology of as received (un-milled) powders, milled powders and sintered nanocomposites were investigated by scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HR-TEM). The mechanical property evaluation of the sintered nanocomposite was done by measuring nanoindentation, micro-hardness and compressive strength.

scholarly journals Reactive Grinding Synthesis of LaBO3 (B: Mn, Fe) Perovskite; Properties for Toluene Total Oxidation

Catalysts ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 633 ◽  
Author(s):  
Bertrand Heidinger ◽  
Sébastien Royer ◽  
Houshang Alamdari ◽  
Jean-Marc Giraudon ◽  
Jean-François Lamonier
Keyword(s):  
Electron Microscopy ◽  
Ball Milling ◽  
Surface Area ◽  
Oxidation Reaction ◽  
High Energy ◽  
Total Oxidation ◽  
X Ray ◽  
Energy Ball ◽  
Reactive Grinding ◽  
Toluene Total Oxidation

LaBO3 (B: Mn, Fe) perovskites were synthesized using a three-step reactive grinding process followed by a calcination at 400 °C for 3 h. The three successive steps are: (i) solid state synthesis (SSR); (ii) high-energy ball milling (HEBM); (iii) low-energy ball milling (LEBM) in wet conditions. The impact of each step of the synthesis on the material characteristics was deeply investigated using physico-chemical techniques (X-ray diffraction (XRD), N2-physisorption, scanning electron microscopy (SEM), transmission electron microscopy (TEM), temperature-programmed reduction (H2-TPR), X-ray photoelectron spectroscopy (XPS)) and the catalytic performances of the synthesized materials were evaluated for the toluene total oxidation reaction. Starting from single oxides, microcrystalline perovskite phase, exhibiting negligible surface areas, is obtained after the SSR step. The HEBM step leads to a drastic reduction of the mean crystal size down to ~20 nm, along with formation of dense aggregates. Due to this strong aggregation, surface area remains low, typically below 4 m2·g−1. In contrast, the second grinding step, namely LEBM, allows particle deagglomeration resulting in increasing the surface area up to 18.8 m2·g−1 for LaFeO3. Regardless of the perovskite composition, the performance toward toluene oxidation reaction increases at each step of the process: SSR < HEBM < LEBM.

Mechanical Alloying of Al2O3-Co Powders Mixture

2006 ◽  
Vol 306-308 ◽  
pp. 1109-1114 ◽  
Author(s):  
W.S. Yeo ◽  
Iskandar Idris Yaacob
Keyword(s):  
Phase Transformation ◽  
Ball Milling ◽  
Milling Time ◽  
High Energy ◽  
X Ray ◽  
Hexagonal Close Packed ◽  
Nominal Size ◽  
Alumina Particles ◽  
Energy Ball ◽  
Ball Milling Technique

Nanocomposite Al2O3-Co was prepared by high-energy ball milling technique. Nanoscaled alumina particles (γ-Al2O3) of 5wt% with nominal size 39 nm were dispersed in cobalt matrix. The phase transformation of the element occurs in the powders mixture during the process was monitored by X-ray diffractometry (XRD). The results showed that cobalt exhibits phase transformation when subjected to ball milling. The phase formation of cobalt was found to depend on the milling intensity. As the milling time increased, the amount of the hexagonal close-packed (hcp) phase decreased.

COMPARISON OF ELECTRODE PROPERTIES OF BINARY, TERNARY AND QUATERNARY NANOCRYSTALLINE Mg2Ni-BASED POWDERS

2011 ◽  
Vol 10 (04n05) ◽  
pp. 1067-1071
Author(s):  
MARYAM MOHRI ◽  
SEYED FARSHID KASHANI-BOZORG
Keyword(s):  
High Energy ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Discharge Duration ◽  
Initial Charge ◽  
Energy Ball ◽  
Composite Microstructure ◽  
Ball Milling Technique

The present investigation is focused on the electrode properties of various nanocrystalline Mg2Ni -based powders synthesized using high energy ball milling technique. The chemical composition was modified by the ternary (Nb) and quaternary ( Al and Nb ) additives. The process parameters were adjusted to achieve nanocrystalline based products. Characterization of the ternary and quaternary milled products using scanning and transmission electron microscopy and X-ray diffraction showed a composite microstructure of an amorphous core surrounded by nanocrystalline Mg2Ni . Electrode made from the quaternary milled product showed superior initial charge density and longer discharge duration.

scholarly journals PENGARUH KITOSAN TERHADAP KRISTALINITAS DAN MORFOLOGI PARTIKEL LITHIUM TITANAT

2014 ◽  
Vol 4 (2) ◽  
pp. 43
Author(s):  
Bharata Dewanto ◽  
Bambang Sunendar Purwasasmita ◽  
Ahmad Nuruddin ◽  
Abdul Halim Daulay ◽  
Susanto Sigit Rahardi
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Ball Milling ◽  
Sol Gel ◽  
Lithium Ion ◽  
High Energy ◽  
X Ray ◽  
Dispersing Agent ◽  
Energy Ball ◽  
Scanning Electron

Baterai terdiri dari katoda, anoda, dan elektrolit. Lithium titanat spinel atau Li4Ti5O12  spinel adalah metal anoda alternatif untuk menggantikan karbon karena memiliki kemampuan untuk memberikan arus besar yang dapat diaplikasikan sebagai baterai pada mobil listrik. Metode yang saat ini sering digunakan untuk pembuatan baterai adalah High Energy Ball Milling, namun energi yang dibutuhkan sangat besar dan waktu pengerjaan dengan metode ini pun cukup lama. Dalam penelitian ini dilakukan sintesis serbuk Li4Ti5O12 ­sebagai anoda baterai lithium ion dengan metode sol-gel dengan variabel kitosan sebagai dispersing agent. Gel yang terbentuk dikalsinasi pada variasi suhu 750oC. Serbuk hasil sintesis dikarakterisasi menggunakan metode XRD (X-ray Diffractometry) dan SEM (Scanning Electron Microscopy). Pada penelitian ini telah berhasil disintesis Li4Ti5O12 dengan metode sol-gel dengan  kitosan sebagai  dispersing agent. Pada suhu kalsinasi 750oC terbentuk 95–97% fasa Li4Ti5O12 yang diketahui dari berdasarkan hasil karakterisasi XRD, kitosan berperan baik sebagai dispersing agent karena dapat meningkatkan kristalinitas, memperkecil ukuran partikel dari serbuk Li4Ti5O12, dan mengurangi aglomerasi partikel. Hasil pengamatan dengan SEM menunjukkan bahwa ukuran dari partikel tergolong pada ukuran submikron yaitu berkisar 75–300 nm yang berpotensi sebagai metal anoda baterai lithium yang mendekati kapasitas secara teori.Kata kunci: baterai lithium ion, anoda, Li4Ti5O12, sol-gel, kitosan

scholarly journals Impact Evaluation of High Energy Ball Milling Homogenization Process in the Phase Distribution of Hydroxyapatite-Barium Titanate Plasma Spray Biocoating

Coatings ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 728
Author(s):  
Roberto Gómez Batres ◽  
Zelma S. Guzmán Escobedo ◽  
Karime Carrera Gutiérrez ◽  
Irene Leal Berumen ◽  
Abel Hurtado Macias ◽  
...  
Keyword(s):  
Barium Titanate ◽  
Ball Milling ◽  
Plasma Spray ◽  
Bonding Strength ◽  
Phase Distribution ◽  
High Energy ◽  
High Energy Ball Milling ◽  
X Ray ◽  
Nanomechanical Properties ◽  
Energy Ball

Air plasma spray technique (APS) is widely used in the biomedical industry for the development of HA-based biocoatings. The present study focuses on the influence of powder homogenization treatment by high-energy ball milling (HEBM) in developing a novel hydroxyapatite-barium titanate (HA/BT) composite coating deposited by APS; in order to compare the impact of the milling process, powders were homogenized by mechanical stirring homogenization (MSH) too. For the two-homogenization process, three weight percent ratios were studied; 10%, 30%, and 50% w/w of BT in the HA matrix. The phase and crystallite size were analyzed by X-ray diffraction patterns (XRD); the BT-phase distribution in the coating was analyzed by backscattered electron image (BSE) with a scanning electron microscope (SEM); the energy-dispersive X-ray spectroscopy (EDS) analysis was used to determinate the Ca/P molar ratio of the coatings, the degree of adhesion (bonding strength) of coatings was determinate by pull-out test according to ASTM C633, and finally the nanomechanical properties was determinate by nanoindentation. In the results, the HEBM powder processing shows better efficiency in phase distribution, being the 30% (w/w) of BT in HA matrix that promotes the best bonding strength performance and failure type conduct (cohesive-type), on the other hand HEBM powder treatment promotes a slightly greater crystal phase stability and crystal shrank conduct against MSH; the HEBM promotes a better behavior in the nanomechanical properties of (i) adhesive strength, (ii) cohesive/adhesive failure-type, (iii) stiffness, (iv) elastic modulus, and (v) hardness properties.

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