Study of the activation process of Mg-based hydrogen storage materials modified by graphite and other carbonaceous compounds

2001 ◽  
Vol 16 (10) ◽  
pp. 2893-2905 ◽  
Author(s):  
S. Bouaricha ◽  
J-P. Dodelet ◽  
D. Guay ◽  
J. Huot ◽  
R. Schulz
Keyword(s):  
Photoelectron Spectroscopy ◽  
High Energy ◽  
Steady Increase ◽  
Surface Oxide Layer ◽  
Activation Process ◽  
Initial Exposure ◽  
X Ray ◽  
Milling Operation ◽  
Energy Ball ◽  
X Ray Absorption

A nanocomposite (Mg–V)nano made of 90 wt% Mg and 10 wt% V was prepared by high-energy ball-milling during 40 h. The activation characteristics of (Mg–V)nano are rather poor, the hydrogen content [H] reaching 4 wt% after more than 100 h (t4wt%) following the initial exposure of the material to H2. Adding 9 wt% graphite to (Mg–V)nano and resuming the milling operation for 30 min leads to the formation of (Mg–V)nano /G, which exhibits a t4wt% value of only 10 min. The addition of more than 9 wt% graphite to (Mg–V)nano does not lead to any significant reduction of the t4wt% value. However, extending the milling period with graphite over 30 min leads to a steady increase in t4wt% and, thus, to a deterioration of the activation characteristics. Comparison of the behavior of graphite with other C-based compounds revealed that perylene (C20H12) and pentacene (C22H14), which are made of linked benzene rings, and thus have a 2D structure similar to that of the graphene sheet, are as effective as graphite in improving the activation characteristics of (Mg–V)nano. A structural investigation of (Mg–V)nano /G as a function of the milling time through both C 1s core-level x-ray photoelectron spectroscopy and C K edge x-ray absorption near-edge spectroscopy has shown that the integrity of graphite is progressively lost as the milling period is extended over 30 min. On the basis of these results, it is hypothesized that the adsorption of graphene layer on freshly created Mg surfaces and the formation of highly reactive C species during milling prevents the re-formation of the surface oxide layer responsible for the poor activation characteristics of untreated (Mg–V)nano

Synchrotron X-ray Absorption Studies of Atomic-Level Alloying in Immiscible Mixtures

1998 ◽  
Vol 524 ◽  
Author(s):  
J.-H. He ◽  
P. J. Schilling ◽  
E. Ma
Keyword(s):  
Ball Milling ◽  
Room Temperature ◽  
High Energy ◽  
Atomic Level ◽  
High Energy Ball Milling ◽  
Edge Structure ◽  
X Ray ◽  
Energy Ball ◽  
Immiscible Mixtures ◽  
X Ray Absorption

ABSTRACTAn X-ray absorption beamline has been developed recently at the electron storage ring of the LSU Center for Advanced Microstructures and Devices. Using Extended X-ray Absorption Fine Structure (EXAFS) and X-ray Absorption Near Edge Structure (XANES), we have studied the local atomic environments in immiscible mixtures processed by high-energy ball milling, a mechanical alloying technique involving heavy deformation. By examining the local coordination and bond distances, it is concluded that atomic-level alloying can indeed be induced between Cu and Fe through milling at room temperature, forming substitutional fcc and bcc solid solutions. In addition to single-phase regions, a two-phase region consisting of fcc/bcc solutions has been found after milling at both room temperature and liquid nitrogen temperature. In contrast to the Cu-Fe system, solid solution formation is not detectable in milled Ag-Fe and Cu-Ta mixtures. This work demonstrates the power of synchrotron EXAFS/XANES experiments in monitoring nonequilibrium alloying on the atomic level. At the same time, the results provide direct experimental evidence of the capability as well as limitations of high-energy ball milling to form alloys in positive-heat-of-mixing systems.

scholarly journals Extended x‐ray‐absorption fine‐structure studies of heat‐treated fcc‐Fe50Cu50powders processed via high‐energy ball milling

1994 ◽  
Vol 76 (10) ◽  
pp. 6322-6324 ◽  
Author(s):  
P. Crespo ◽  
A. Hernando ◽  
A. Garcia Escorial ◽  
K. M. Kemner ◽  
V. G. Harris
Keyword(s):  
Fine Structure ◽  
Ball Milling ◽  
High Energy ◽  
High Energy Ball Milling ◽  
X Ray ◽  
Absorption Fine ◽  
Heat Treated ◽  
Energy Ball ◽  
X Ray Absorption

Possible evidence for the stabilization of β–carbon nitride by high-energy ball milling

1999 ◽  
Vol 14 (6) ◽  
pp. 2488-2499 ◽  
Author(s):  
Y. Fahmy ◽  
T. D. Shen ◽  
D. A. Tucker ◽  
R. L. Spontak ◽  
C. C. Koch
Keyword(s):  
Ball Milling ◽  
Photoelectron Spectroscopy ◽  
Energy Levels ◽  
Hexagonal Lattice ◽  
High Energy ◽  
Lattice Parameter ◽  
High Energy Ball Milling ◽  
X Ray ◽  
Liquid Phases ◽  
Energy Ball

The possibility of stabilizing the theoretically predicted β–C3N4 phase by high-energy ball milling is investigated. Charges of graphitic carbon were milled with and without minor alloying additions under different atmospheric media, namely gas and/or liquid phases of nitrogen, air, or ammonia. Milling was performed at either of two energy levels for periods of up to 48 h. The β–C3N4 phase was found to exist as small crystallites in a matrix of primarily amorphous carbon at volume fractions estimated between 5 and 10 at.%. High-resolution electron diffraction and x-ray diffraction indicate that the crystalline nature of the C3N4 phase corresponds with a hexagonal lattice with a = 6.46 Å and c/a = 0.374, which are within 2% of the theoretically calculated lattice parameter values. Analysis of electron energy-loss spectroscopy (EELS), x-ray photoelectron spectroscopy (XPS), and Fourier transform infrared (FTIR) spectra verify the presence of chemically bonded carbon and nitrogen with chemical states reflecting combined sp2 and sp3 hybridization. Chemical analysis confirms nitrogen enrichment at levels consistent with the C3N4 stoichiometry and the estimated degree of stabilization. The possible mechanism(s) responsible for the stabilization of the β–C3N4 phase are briefly discussed.

A comparison of the extended x-ray absorption fine structure of nanocrystalline ZrO2prepared by high-energy ball milling and other methods

2003 ◽  
Vol 15 (3) ◽  
pp. 431-440 ◽  
Author(s):  
Alan V Chadwick ◽  
Marina J Pooley ◽  
K Erasmus Rammutla ◽  
Shelley L P Savin ◽  
Aline Rougier
Keyword(s):  
Fine Structure ◽  
Ball Milling ◽  
High Energy ◽  
High Energy Ball Milling ◽  
X Ray ◽  
Absorption Fine ◽  
Energy Ball ◽  
X Ray Absorption

X-ray absorption, neutron diffraction, and Mössbauer effect studies of MnZn–ferrite processed through high-energy ball milling

1999 ◽  
Vol 85 (8) ◽  
pp. 5172-5174 ◽  
Author(s):  
D. J. Fatemi ◽  
V. G. Harris ◽  
M. X. Chen ◽  
S. K. Malik ◽  
W. B. Yelon ◽  
...  
Keyword(s):  
Neutron Diffraction ◽  
Ball Milling ◽  
Mössbauer Effect ◽  
High Energy ◽  
High Energy Ball Milling ◽  
Mossbauer Effect ◽  
Mnzn Ferrite ◽  
X Ray ◽  
Energy Ball ◽  
X Ray Absorption

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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