Mechanochemical study of the hydriding properties of nanostructured Mg2Ni–Ni composites

2004 ◽  
Vol 19 (11) ◽  
pp. 3279-3289 ◽  
Author(s):  
G. Mulas ◽  
L. Schiffini ◽  
G. Cocco
Keyword(s):  
Mechanical Treatment ◽  
Hydrogen Uptake ◽  
Absorption Kinetics ◽  
Dissociative Chemisorption ◽  
Hydrogen Activation ◽  
Reactive Milling ◽  
Ni Powder ◽  
Thermodynamic Conditions ◽  
Powder Composites ◽  
Hydriding Kinetics

A comprehensive approach is presented for defining hydrogen activation and absorbing kinetics in heterogeneous Mg2Ni/Ni powder composites that were subjected to mechanical refinement. Hydriding tests were performed under conventional hydrogen dissolving and under reactive milling. Irrespective of the absorbing mode, the absorption kinetics is deceleratory throughout. Under conventional thermodynamic conditions, the hydriding rate depends strongly on the microstructural features of both the absorbing Mg2Ni intermetallic and the Ni phase. The latter plays an important role in the dissociative chemisorption of hydrogen. Under milling the hydrogen uptake and the hydriding kinetics also depend on the intensity of the milling processing, IM (watt g−1), with the absorption rate increasing exponentially with IM. The mechanical treatment was found effective even when thermodynamic absorption reached saturation level. Hydriding rates, mechanochemical gains, and instantaneous mechanochemical yields (mol J−1) were used to compare the processes on an absolute scale and to spotlight possible mechanisms controlling kinetics trends and absorbing features under milling.

Hydriding kinetics and process parameters in reactive milling

2005 ◽  
Vol 404-406 ◽  
pp. 343-346 ◽  
Author(s):  
G. Mulas ◽  
L. Schiffini ◽  
G. Tanda ◽  
G. Cocco
Keyword(s):  
Process Parameters ◽  
Reactive Milling ◽  
Hydriding Kinetics

Texture development in AgNi powder composites

1994 ◽  
Vol 175 (1-2) ◽  
pp. 113-124 ◽  
Author(s):  
R.E. Bolmaro ◽  
R.V. Browning ◽  
F.M. Guerra ◽  
A.D. Rollett
Keyword(s):  
Texture Development ◽  
Ni Powder ◽  
Powder Composites

Formation of Sintered “PN85Yu15 – Ni” Powder Composites by Using the SPS Method

2014 ◽  
Vol 698 ◽  
pp. 299-304 ◽  
Author(s):  
Lilia Shevtsova ◽  
Alexander Anisimov ◽  
Sergey Nagavkin
Keyword(s):  
Nickel Aluminide ◽  
Bending Strength ◽  
Nickel Content ◽  
Intermetallic Particles ◽  
Plasma Sintering ◽  
Ni Powder ◽  
Sintered Powder ◽  
Powder Composites ◽  
Spark Plasma ◽  
Sintered Materials

PN85U15 - Ni composites were obtained by spark plasma sintering (SPS) of the powder mixture consisted of nickel and nickel aluminide. Particular attention in this study was focused on the discussion of the problem concerning the influence of the nickel content on mechanical properties of the sintered composites. The microstructure of the sintered materials consisted of spherical intermetallic particles homogeneously distributed in the nickel matrix. The relative density of all sintered materials was higher than 90 %. The hardness of the fabricated composites decreased from 3100 MPa (PN85U15 sintered powder) to 2500 MPa (70 % PN85U15 with 30 % Ni). It was found that the PN85U15 – Ni composite containing approximately 30 wt. % of Ni possessed the highest bending strength (1900 MPa).

scholarly journals Milling Processes and Hydrogen Storage Properties of Mg-Graphene Composites

2019 ◽  
Vol 25 (3) ◽  
pp. 286-291
Author(s):  
Young Jun KWAK ◽  
Eunho CHOI ◽  
Myoung Youp SONG
Keyword(s):  
Hydrogen Storage ◽  
Hydrogen Uptake ◽  
Weight Percent ◽  
Particle Sizes ◽  
Cycle Number ◽  
Reactive Milling ◽  
Milling In Hydrogen ◽  
Storage Properties ◽  
Effective Hydrogen ◽  
Uptake And Release

Graphene was chosen as an additive to improve the hydrogen uptake and release properties of magnesium (Mg). Five weight percent of graphene was added to Mg or pre-milled Mg by milling in hydrogen (reactive milling). The milling processes and hydrogen uptake and release properties of the graphene-added Mg were investigated. Adding graphene to Mg and then milling the mixture of Mg and graphene in hydrogen for 6 h [named M5G (6 h)] had little effects on the improvement of hydrogen uptake and release properties of Mg. Pre-milling of Mg (for 24 h) and then adding 5 wt.% of graphene by milling in hydrogen (for 30 min) (named M5G) significantly increased the hydrogen uptake and release rates and the quantities of hydrogen absorbed and released for 60 min of Mg. The activation of M5G was completed after cycle number, CN, of two (CN = 2). M5G had a high effective hydrogen-storage capacity of 6.21 wt.% at 623 K in 12 bar H2 at CN = 3. M5G released 0.25 wt.% hydrogen for 2.5 min and 5.28 wt.% hydrogen for 60 min H2 in 1.0 bar H2 at 623 K at CN = 3. Pre-milling of Mg and then adding graphene by milling in hydrogen and hydrogen uptake-release cycling are believed to create defects, produce cracks and clean surfaces, and decrease particle sizes. DOI: http://dx.doi.org/10.5755/j01.ms.25.3.20567

Metallurgical Effects of Grain Boundary Ledges

1977 ◽  
Vol 35 ◽  
pp. 126-129
Author(s):  
L.E. Murr
Keyword(s):  
Grain Boundary ◽  
Quantitative Data ◽  
Mechanical Treatment ◽  
Unit Length ◽  
Physical And Mechanical Properties ◽  
Direct Observations ◽  
Transmission Electron ◽  
Properties Of Materials ◽  
Thermo Mechanical Treatment ◽  
Ledge Density

Ledges in grain boundaries can be identified by their characteristic contrast features (straight, black-white lines) distinct from those of lattice dislocations, for example1,2 [see Fig. 1(a) and (b)]. Simple contrast rules as pointed out by Murr and Venkatesh2, can be established so that ledges may be recognized with come confidence, and the number of ledges per unit length of grain boundary (referred to as the ledge density, m) measured by direct observations in the transmission electron microscope. Such measurements can then give rise to quantitative data which can be used to provide evidence for the influence of ledges on the physical and mechanical properties of materials.It has been shown that ledge density can be systematically altered in some metals by thermo-mechanical treatment3,4.

Electrical Conductivity of Ni-YSZ Anode for SOFCs According to the Ni Powder Size Variations in Core-shell Structure

2015 ◽  
Vol 53 (4) ◽  
pp. 287-293
Author(s):  
Byung-Hyun Choi ◽  
Young Jin Kang ◽  
Sung-Hun Jung ◽  
Yong-Tae An ◽  
Mi-Jung Ji
Keyword(s):  
Electrical Conductivity ◽  
Shell Structure ◽  
Core Shell ◽  
Powder Size ◽  
Ni Powder ◽  
Core Shell Structure

RESULTS OF RESEARCH OF MODERN TECHNOLOGIES OF WEED CONTROL IN INDUSTRIAL CROPS OF CORN FOR GRAIN

2020 ◽  
Author(s):  
O.N. Negreba ◽  
◽  
E.V. Bondarenko ◽  
M.A. Belik ◽  
T.A. Yurina ◽  
...  
Keyword(s):  
Weed Control ◽  
Chemical Treatment ◽  
Mechanical Treatment ◽  
Plant Protection ◽  
Protection System ◽  
Plant Protection System ◽  
Modern Technologies ◽  
Basic Version

The article presents the results of research on modern technologies for weed control in production crops of corn for grain. The best results were obtained in the basic version of technology No. 5 with the following plant protection system: mechanical treatment of crops (cross-row harrowing and three row-to-row cultivation) in combination with chemical treatment with the herbicide Mаister-150 g/ha.

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