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.

Microstructural Transformations of an Amorphous Fe90 Zr10 Alloy Induced by High-Energy Ball-Milling

2006 ◽  
Vol 510-511 ◽  
pp. 698-701
Author(s):  
Pyuck Pa Choi ◽  
Young Soon Kwon ◽  
Ji Soon Kim ◽  
Dae Hwan Kwon
Keyword(s):  
Ball Milling ◽  
Milling Time ◽  
High Energy ◽  
High Energy Ball Milling ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Melt Spun ◽  
Energy Ball ◽  
Induced Crystallization

Mechanically induced crystallization of an amorphous Fe90Zr10 alloy was studied by means of X-ray diffraction (XRD) and differential scanning calorimetry (DSC). Under high-energy ball-milling in an AGO-2 mill, melt-spun Fe90Zr10 ribbons undergo crystallization into BCC α- Fe(Zr). Zr atoms are found to be solved in the Fe(Zr) grains up to a maximum supersaturation of about 3.5 at.% Zr, where it can be presumed that the remaining Zr atoms are segregated in the grainboundaries. The decomposition degree of the amorphous phase increases with increasing milling time and intensity. It is proposed that the observed crystallization is deformation-induced and rather not attribute to local temperature rises during ball-collisions.

Decomposition and Crystallization Induced by High-Energy Ball-Milling

2007 ◽  
Vol 119 ◽  
pp. 1-4 ◽  
Author(s):  
Young Soon Kwon ◽  
Ji Soon Kim ◽  
Cheol Eeh Kim
Keyword(s):  
Grain Size ◽  
Phase Transformation ◽  
Ball Milling ◽  
Milling Time ◽  
High Energy ◽  
Thermally Induced ◽  
Average Grain Size ◽  
Powder Particles ◽  
Energy Ball ◽  
Decomposition Behavior

Phase transformation induced by ball-milling was studied in this work. It was found that amorphous Fe90Zr10 ribbons undergo crystallization into BCC α-Fe(Zr) under milling in an AGO-2 mill. The decomposition degree of the amorphous phase increased with increasing milling time and intensity. Analyses of samples milled at different speeds suggested that the observed crystallization is a deformation-induced process rather than a thermally induced one. In addition, the decomposition behavior of a FeSn intermetallic under ball-milling was carefully studied. Upon milling a large amount of the FeSn intermetallic decomposed into Fe5Sn3 and FeSn2, where the average grain size of the product phases stayed nearly constant with milling-time. It is suggested that the mechanically driven decomposition of FeSn results from local melting of powder particles due to high temperature pulses during ball collisions.

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.

In situsynchrotron X-ray powder diffraction for studying the role of induced structural defects on the thermoluminescence mechanism of nanocrystalline LiF

2016 ◽  
Vol 23 (2) ◽  
pp. 501-509
Author(s):  
Mostafa El Ashmawy ◽  
Hany Amer ◽  
Mahmoud Abdellatief
Keyword(s):  
Ball Milling ◽  
Powder Diffraction ◽  
Milling Time ◽  
Relative Concentration ◽  
High Energy ◽  
Structural Defects ◽  
X Ray ◽  
Energy Ball

The correlation between the thermoluminescence (TL) response of nanocrystalline LiF and its microstructure was studied. To investigate the detailed TL mechanism, the glow curves of nanocrystalline LiF samples produced by high-energy ball-milling were analyzed. The microstructure of the prepared samples was analyzed by synchrotron X-ray powder diffraction (XRPD) at room temperature. Then, the microstructure of a representative pulverized sample was investigated in detail by performingin situXRPD in both isothermal and non-isothermal modes. In the present study, the dislocations produced by ball-milling alter the microstructure of the lattice where the relative concentration of the vacancies, responsible for the TL response, changes with milling time. An enhancement in the TL response was recorded for nanocrystalline LiF at high-temperature traps (after dislocations recovery starts >425 K). It is also found that vacancies are playing a major role in the dislocations recovery mechanism. Moreover, the interactions among vacancies–dislocations and/or dislocations–dislocations weaken the TL response.

Mechanically induced devitrifications of ball-milled Zr70Pd20Ni10 glassy alloy powders

2003 ◽  
Vol 18 (2) ◽  
pp. 250-253 ◽  
Author(s):  
M. Sherif El-Eskandarany ◽  
J. Saida ◽  
A. Inoue
Keyword(s):  
Ball Milling ◽  
Lattice Constant ◽  
Milling Time ◽  
Metastable Phase ◽  
Glassy Alloy ◽  
High Energy ◽  
Face Centered Cubic ◽  
Energy Ball ◽  
Face Centered ◽  
Ball Milling Technique

Mechanical alloying using a high-energy ball milling technique was used to fabricate a single glassy phase of Zr70Pd20Ni10 alloy powders after 100 h milling time. Annealing the glassy powders at a temperature just below the crystallization onset temperature led to thermally enhanced devitrification and the formation of a metastable big-cube phase with a lattice constant of 1.2289 nm. The same metastable phase was obtained upon subjecting the end product of the glassy powders to further ball milling time (150 h). This metastable big-cube phase could no longer withstand the shear and impact stresses generated by the milling media and transformed into a new metastable phase of face-centered cubic Zr70Pd20Ni10. The lattice constant of this metastable phase was calculated to be 0.56838 nm. These metastable phases are new and have never been, so far as we know, reported for the ternary Zr–Pd–Ni system or its binary phase relations.

102213 Use of High Energy Ball Milling on the Sintering Optimization of Alumina Ceramics

2010 ◽  
Vol 660-661 ◽  
pp. 701-706
Author(s):  
Helio R. Simoni ◽  
Eduardo Saito ◽  
Claudinei dos Santos ◽  
Felipe Antunes Santos ◽  
Alfeu Saraiva Ramos ◽  
...  
Keyword(s):  
Crystallite Size ◽  
Ball Milling ◽  
Milling Time ◽  
High Energy ◽  
High Energy Ball Milling ◽  
Green Density ◽  
Alumina Ceramics ◽  
X Ray Diffraction ◽  
X Ray ◽  
Energy Ball

In this work, the effect of the milling time on the densification of the alumina ceramics with or without 5wt.%Y2O3, is evaluated, using high-energy ball milling. The milling was performed with different times of 0, 2, 5 or 10 hours. All powders, milled at different times, were characterized by X-Ray Diffraction presenting a reduction of the crystalline degree and crystallite size as function of the milling time increasing. The powders were compacted by cold uniaxial pressing and sintered at 1550°C-60min. Green density of the compacts presented an increasing as function of the milling time and sintered samples presented evolution on the densification as function of the reduction of the crystallite size of the milled powders.

Catalytic Effect of Ti on H-Desorption/Absorption Properties in MgH2 Prepared by Ball Milling

2014 ◽  
Vol 687-691 ◽  
pp. 4335-4338
Author(s):  
Yan Wang
Keyword(s):  
Ball Milling ◽  
Milling Time ◽  
Hydrogen Desorption ◽  
High Energy ◽  
X Ray Diffraction ◽  
Absorption Properties ◽  
X Ray ◽  
Milled Sample ◽  
Energy Ball ◽  
Kinetics Of

We report on the preparation and hydrogen desorption/absorption kinetics of nanocrystalline magnesium hydride (MgH2) added commercial Ti by high-energy ball milling. The phase and composition of the as-milled powders are characterized by X-ray diffraction (XRD). The results show that the milled sample contained MgH2phase, Ti phase and small amount of MgO phase. When the milling time is 30 h, the hydrogen desorption property of MgH2has been investigated and found that the sample releases 0.43, 0.86 and 0.90 wt% H2in 200 minutes at 280, 290 and 300oC , respectively. Moreover, the sample absorbs 0.48, 0.0.58 and 0.61 wt% H2in 15 minutes at 280, 290 and 300oC , respectively. It can be seen that the kinetics of hydrogen desorption/absorption of MgH2-Ti composite has been greatly enhanced compared to the pure MgH2.

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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