Production of Magnetic Nanopowders by Pulsed Sonoelectrochemistry

1996 ◽  
Vol 451 ◽  
Author(s):  
J-L. Delplancke ◽  
O. Bouesnard ◽  
J. Reisse ◽  
R. Winand
Keyword(s):  
High Current Density ◽  
Ternary Alloys ◽  
High Current ◽  
Iron Cobalt ◽  
X Ray ◽  
Nickel Powders ◽  
Nickel Cobalt ◽  
Transmission Electron ◽  
Iron Nickel ◽  
Cobalt And Nickel

ABSTRACTSonoelectrochemistry, or pulsed electrodeposition at high current density in presence of high intensity ultrasound, is used to produce magnetic powders with a mean diameter in the range of 100 nm. Pure iron, cobalt and nickel powders are produced together with their binary and ternary alloys. The powders are crystalline and homogeneous as observed by scanning and transmission electron microscopy, electron diffraction and X-ray fluorescence. The compositions of the binary and ternary alloy powders reproduce strictly the iron, nickel and cobalt compositions of the starting electrolytes except for the nickel-cobalt alloys.

Electrochemical Synthesis of Binary Carbides of Tungsten and Iron (Nickel, Cobalt) in Halide-Oxide Melts at 823 K

2007 ◽  
Vol 62 (12) ◽  
pp. 749-753
Author(s):  
Hasbi Kushkhov ◽  
Marina Adamokova ◽  
Vitalij Kvashin ◽  
Anzor Kardanov ◽  
Svetlana Gramoteeva
Keyword(s):  
Acid Base ◽  
Iron Carbides ◽  
Pressing Method ◽  
X Ray ◽  
Nickel Powders ◽  
Nickel Cobalt ◽  
Cobalt Iron ◽  
Iron Nickel ◽  
Oxide Melts ◽  
Cobalt And Nickel

Iron, cobalt and nickel powders are used as binding components for the production of articles of tungsten carbide by the hot pressing method. This fact and the unique properties of binary carbides of tungsten-iron triad metals encouraged the search for new ways of their synthesis. In the present work, the attempt to synthezise binary tungsten-nickel (cobalt, iron) carbides in molten KCl-NaCl-CsCl at 823 K was made. As a result of voltammetry research, it was established that in eutectic KCl-NaCl-CsCl melts the deposition potentials ofWand Ni (Co, Fe) differ by 150 - 350 mV from each other, which makes their co-deposition difficult. It is possible to shift the deposition potentials of tungsten and metals of the iron triad metals towards each other by changing the acid-base properties of the melt. The products of electrolysis in these molten system were identified by X-ray analysis. They are mixtures of tungsten and nickel (cobalt, iron) carbides: Ni2W4C, W6C2.54; Co3W3C, Co6W6C, W2C, Co3C; FeW3C.

scholarly journals Theoretical and Experimental Evaluation of Particle size Effect of Iron , Cobalt ,and Nickel Powders Suspended in Al Dura oil on XRF Intensities

2007 ◽  
Vol 4 (3) ◽  
pp. 475-481
Author(s):  
Baghdad Science Journal
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Laser System ◽  
Particle Size Effect ◽  
Particle Sizes ◽  
Iron Cobalt ◽  
X Ray ◽  
Nickel Powders ◽  
Good Agreement ◽  
Cobalt And Nickel

Iron , Cobalt , and Nickel powders with different particle sizes were subjected to sieving and He-Ne laser system to determine the particle size . 1wt% from each powders was blended carefully with 99wt% from Iraqi oil . Microscopic examination were carried for all samples to reveal the particle size distribution . A Siemens type SRS sequential wavelength dispersive(WDS) X-ray spectrometer was used to analyze all samples , and the XRF intensity were determined experimentally and theoretically for all suspended samples , Good agreement between theoretical and experimental results were found .

Evolution of microstructure in TiC/NiCr cermet induced by electropulsing

2003 ◽  
Vol 18 (7) ◽  
pp. 1543-1550 ◽  
Author(s):  
W. Zhang ◽  
M. L. Sui ◽  
Y. Z. Zhou ◽  
J. D. Guo ◽  
G. H. He ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Current Density ◽  
High Current ◽  
X Ray Diffraction ◽  
X Ray ◽  
Deformation Twins ◽  
Transmission Electron ◽  
Transient Rise ◽  
Evolution Of Microstructure

Microstructures of a TiC/Ni80Cr20 cermet, subjected to single high-current-density electropulsing, were characterized by x-ray diffraction, transmission electron microscopy, and high-resolution transmission electron microscopy. Under the electropulsing, the shift of NiCr peaks versus the reverse change of TiC counterparts illustrates that the treatment gives rise to strong thermal stress impacting on the cermet. The stress, accompanied by the transient rise of temperature, led to microstructural evolutions of the cermet. Some nanostructured TiC grains, consisting of many nanocrystallites with small-angle grain boundaries, developed during electropulsing. Also, many regions teemed with coexisting nanosized TiC and NiCr crystallites, which possessed good bonding. Within the NiCr regions, large amounts of deformation twins were produced by the electropulsing.

Formation of Graphite Encapsulated Nickel Nanoparticles by Ball Milling and Annealing of Expanded Graphite with Nickel

2011 ◽  
Vol 80-81 ◽  
pp. 217-220 ◽  
Author(s):  
Xue Qing Yue ◽  
Hai Jun Fu ◽  
Da Jun Li
Keyword(s):  
Electron Microscope ◽  
Ball Milling ◽  
Transmission Electron Microscope ◽  
Nickel Nanoparticles ◽  
Size Range ◽  
Expanded Graphite ◽  
X Ray Diffraction ◽  
X Ray ◽  
Nickel Powders ◽  
Transmission Electron

Graphite encapsulated nickel nanoparticles were prepared by ball milling andsubsequently annealing a mixture of expanded graphite with nickel powders. The products were characterized by transmission electron microscope and X-ray diffraction. The formation mechanism of the products was discussed. Results show that the products have a size range of 20-150 nm. The graphite and nickel in the products all exhibit a high crystallinity.

DIFFUSION OF Ni63 IN IRON, COBALT, NICKEL, AND TWO IRON–NICKEL ALLOYS

1959 ◽  
Vol 37 (10) ◽  
pp. 1629-1636 ◽  
Author(s):  
J. R. MacEwan ◽  
J. U. MacEwan ◽  
L. Yaffe
Keyword(s):  
Surface Activity ◽  
Nickel Alloys ◽  
Nickel Content ◽  
The Self ◽  
Iron Cobalt ◽  
Self Diffusion ◽  
Cobalt Nickel ◽  
Iron Nickel ◽  
Iron Nickel Alloys ◽  
Cobalt And Nickel

The self-diffusion of nickel and the diffusion of Ni63 into iron, cobalt, and two iron–nickel alloys was studied using the technique of decrease in surface activity, The nickel self-diffusion results are compared to previously reported values. Nickel is found to diffuse more slowly than iron in the iron-rich portion of the iron–nickel system. The rate of nickel diffusion increases with increasing nickel content. A comparison is made between the present results for diffusion of Ni63 into iron, cobalt, and nickel with reported values for diffusion of Co60 and Fe59 in the same metals. In each solvent, the magnitudes of the activation energies, Q, are such that QNi > QCo > QFe.

Morphology and Chemical Composition of Silicon Carbide Surfaces Interacting with Iron, Cobalt, and Nickel in Microscratching

2018 ◽  
Vol 284 ◽  
pp. 363-368 ◽  
Author(s):  
V.A. Nosenko ◽  
A.V. Fetisov ◽  
V.Ye. Puzyrkova
Keyword(s):  
Silicon Carbide ◽  
Electron Microscope ◽  
Chemical Composition ◽  
Iron Cobalt ◽  
Beam Electron ◽  
X Ray ◽  
Metal Atoms ◽  
Dual Beam ◽  
Structure Of Metal ◽  
Cobalt And Nickel

The paper dwells upon the specifics of worn spots being formed on a silicon-carbide crystal in microscratching of iron, cobalt, and nickel. Analysis was done using a Versa 3D dual-beam electron microscope. The chemical composition of worn spots was studied by local X-ray microanalysis. It was found out that the amount of metal transferred to the silicon-carbide worn spot was associated with the electron structure of metal atoms.

scholarly journals XXI.—On the Curves of Magnetisation for Films of Iron, Cobalt, and Nickel

1897 ◽  
Vol 38 (3) ◽  
pp. 757-764
Author(s):  
J. C. Beattie
Keyword(s):  
Magnetic Properties ◽  
Iron Cobalt ◽  
Iron Nickel ◽  
Very High ◽  
Cobalt And Nickel

By films of iron, nickel, and cobalt are here meant electrolytic deposits of these metals on platinised glass. The magnetic properties of such films are interesting in various ways. For example, when they are longitudinally magnetised, we have the case of a magnet where the ratio of length to breadth is very great, and where, consequently, the demagnetising force is very small, e.g., with a film of a 5000th part of a millimetre in thickness, and 5 mms. in length, we have a ratio in length to thickness of 25,000: 1; at the same time the film is so small that it can be tested in very high uniform fields.

Hydrogenation Properties of Mg-Co and Its Related Alloys

2005 ◽  
Vol 475-479 ◽  
pp. 2453-2456
Author(s):  
Y. Zhang ◽  
Y. Tsushio ◽  
Hirotoshi Enoki ◽  
Etsuo Akiba
Keyword(s):  
Binary Alloys ◽  
Lattice Parameter ◽  
Ternary Alloys ◽  
Body Centered Cubic ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Co Concentration ◽  
Bcc Structure ◽  
Co Alloys

Novel Mg-Co binary alloys with BCC (body-centered cubic) structure have been successfully synthesized by means of mechanical alloying technique. The formation of BCC structure was confirmed by X-ray diffraction and transmission electron microscopy. Mg-Co alloys were found in the range of Co concentration between 37 and 80 atomic %. All the Mg-Co alloys synthesized absorbed hydrogen below 373K. The maximum hydrogen capacity of these alloys reaches 2.7 mass %. However, desorption of hydrogen at 373 K has not been observed yet. Mg- Co-X (X = B and Ni) ternary alloys with BCC structure have also been synthesized. The lattice parameter of both alloys is lower than that of Mg-Co binary alloys, meanwhile the maximum hydrogen content of both alloys also decreased.

STEM investigation of the chemistry and bonding changes associated with the grain boundary embrittlement of Cu by Bi

1996 ◽  
Vol 54 ◽  
pp. 526-527
Author(s):  
V. J. Keast ◽  
J. Bruley ◽  
D. B. Williams
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
High Current Density ◽  
High Current ◽  
Fracture Path ◽  
Scanning Electron Micrograph ◽  
Edge Structure ◽  
X Ray ◽  
Grain Boundary Embrittlement ◽  
Electron Energy Loss

It has long been known that trace amounts of Bi can embrittle Cu after appropriate heat treatments. The Bi segregates to the grain boundaries and weakens them such that failure occurs through intergranular fracture without plastic deformation. This behavior is demonstrated in the scanning electron micrograph of a typical Cu-Bi fracture surface in Figure 1. It is known that the Bi extends for only a few atomic layers into the grains on either side of the grain boundary. This narrow segregation width was been confirmed using Energy Dispersive X-ray Spectroscopy (EDS) on a VG HB603 STEM. Figure 2 shows the ratio of Bi to Cu as the probe is stepped across the grain boundary.The segregation behavior is well understood, however it is not yet properly understood how the Bi causes embrittlement once it is at the grain boundaries. The Bi must change the bonding at the boundaries so that the boundaries become weak and hence the most likely fracture path. The Electron Energy Loss Near Edge Structure (ELNES) coupled with the small probes and high current density available in a field emission STEM can provide information about the localized electronic structure and hence bonding at grain boundaries. Previous investigations indicated that the near edge structure of Cu was altered at the grain boundaries due to the presence of Bi.

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