SYNTHESIS OF AN IONIC LIQUID-BASED MAGNETORHEOLOGICAL FLUID DISPERSING Fe84Nb3V4B9 NANOCRYSTALLINE POWDERS

2010 ◽  
Vol 24 (10) ◽  
pp. 1227-1234 ◽  
Author(s):  
LINGFEI CAO ◽  
HYUNSEO PARK ◽  
GJERGJ DODBIBA ◽  
TOYOHISA FUJITA
Keyword(s):  
Ionic Liquid ◽  
Mechanical Alloying ◽  
Nanocrystalline Powders ◽  
Magnetic Flux Density ◽  
Magnetic Clusters ◽  
Mr Fluid ◽  
Structure Morphology ◽  
Average Grain Size ◽  
Digital Microscope ◽  
20 Nm

A new magnetorheological (MR) fluid was synthesized by dispersing Fe 84 Nb 3 V 4 B 9 nanocrystalline powders in a nonvolatile ionic liquid (N,N-diethyl-N-methyl-N-(2-methoxyethyl) ammonium tetrafluoroborate), which is stable from 282K to 573K. The structure, morphology, and magnetization of Fe 84 Nb 3 V 4 B 9 nanocrystalline powders prepared by mechanical alloying were analyzed by using an X-ray diffractometer (XRD), a vibrating sample magnetometer (VSM), and a scanning electron microscopy (SEM), respectively. The magnetic clusters of the synthesized MR fluid were observed by using a digital microscope, and its MR properties were measured by using a cone-plate type viscometer. The experimental results showed that Fe 84 Nb 3 V 4 B 9 nanocrystalline powders with an average grain size of 10–20 nm can be prepared by mechanical alloying. The MR fluid is magnetic-field-responsive, behaves like non-Newtonian fluids, and its magnetorheological properties are influenced by the applied magnetic flux density and the width of magnetic clusters.

The Magnetic and Photo-Catalytic Properties of Fe Doped TiO2 Nanocrystalline Powder Synthesized by Mechanical Alloying

2007 ◽  
Vol 534-536 ◽  
pp. 229-232 ◽  
Author(s):  
Young Rang Uhm ◽  
S.H. Woo ◽  
Min Ku Lee ◽  
Chang Kyu Rhee
Keyword(s):  
Mechanical Alloying ◽  
Paramagnetic Phase ◽  
Uv Absorption ◽  
Spherical Particles ◽  
Nanocrystalline Powders ◽  
Ferromagnetic Phase ◽  
Nanocrystalline Powder ◽  
Mechanically Alloyed ◽  
Doped Tio2 ◽  
Average Grain Size

Fe-doped TiO2 nanocrystalline powders were prepared by mechanical alloying (MA) by varying Fe contents up to 8.0 wt.%. The TEM analyses were carried out to clarify morphologies and position of Fe within the mechanically alloyed powders. The Fe-doped powder consisted of spherical particles, and the average grain size was less than 10 nm. For the Fe-doped TiO2, the color of the powders changed from white to bright yellow with increasing concentration of Fe. The UVvis absorption showed that the UV absorption for the Fe-doped powder shifted to a longer wavelength (red shift) and the photo-efficiency was enhanced. The absorption threshold depends on the concentration of nano-sized Fe dopant. Mössbauer spectrum for 4 wt.% Fe showed the ferromagnetic phase (sextet) and paramagnetic phase (doublet). However, the only paramagnetic phase (doublet) was seen for 8 wt.% Fe. As the Fe concentration increased up to 4 wt.%, the UV-vis absorption and the magnetization were increased. The beneficial effect of Fe doping for photocatalysis and ferromagnetism was observed at the critical dopant concentration of 4 wt.%. Based on the UV absorption and magnetization, the dopant level was localized to the valence band of TiO2.

Reversible grain size changes in ball-milled nanocrystalline Fe–Cu alloys

1992 ◽  
Vol 7 (8) ◽  
pp. 1980-1983 ◽  
Author(s):  
J. Eckert ◽  
J.C. Holzer ◽  
C.E. Krill ◽  
W.L. Johnson
Keyword(s):  
Grain Size ◽  
Mechanical Alloying ◽  
Single Phase ◽  
Underlying Mechanism ◽  
Solution Hardening ◽  
Cu Alloys ◽  
Average Grain Size ◽  
20 Nm ◽  
Composition Changes ◽  
Fcc Structure

Nanocrystalline FexCu100−x solid solutions (x < 60) with single-phase fcc structure have been prepared by mechanical alloying. The average grain size of the powders (8–20 nm) depends on the composition of the material. Varying the composition changes the grain size reversibly. This can be explained by the underlying mechanism of plastic deformation and solution hardening during mechanical alloying coupled with the recovery behavior of the material.

Preparation of Al-Fe-V-Si Nanocrystalline Powders by Double Mechanical Alloying

2000 ◽  
Vol 331-337 ◽  
pp. 1225-1230 ◽  
Author(s):  
L.J. Zheng ◽  
J.X. Lin ◽  
B.S. Li ◽  
B.J. Zhang ◽  
M.K. Tseng
Keyword(s):  
Mechanical Alloying ◽  
Nanocrystalline Powders

Dynamic Evolution of Defect Structures during Spall Failure of Nanocrystalline Al

MRS Advances ◽  
2016 ◽  
Vol 1 (58) ◽  
pp. 3853-3858
Author(s):  
Kathleen Coleman ◽  
Garvit Agarwal ◽  
Avinash M. Dongare
Keyword(s):  
Shock Loading ◽  
Spall Strength ◽  
Dynamic Evolution ◽  
Defect Structures ◽  
Deformation And Failure ◽  
Average Grain Size ◽  
Initial Shock ◽  
Dynamics Simulations ◽  
20 Nm ◽  
Spall Failure

ABSTRACTThe dynamic evolution and interaction of defects under the conditions of shock loading in nanocrystalline Al with an average grain size of 20 nm is investigated using molecular dynamics simulations for an impact velocity of 1 km/s. Four stages of defect evolution are identified during shock deformation and failure that correspond to the initial shock compression (I), the propagation of the compression wave (II), the propagation and interaction of the reflected tensile waves (III), and the nucleation, growth, and coalescence of voids (IV). The results suggest that the spall strength of the nanocrystalline Al system is attributed to a high density of Shockley partials and a slightly lower density of twinning partials (twins) in the material experiencing the peak tensile pressures.

ATOMIC FORCE MICROSCOPY AND XRD ANALYSIS OF SILVER FILMS DEPOSITED BY THERMAL EVAPORATION

2006 ◽  
Vol 20 (02) ◽  
pp. 217-231 ◽  
Author(s):  
MUHAMMAD MAQBOOL ◽  
TAHIRZEB KHAN
Keyword(s):  
Atomic Force Microscopy ◽  
Grain Size ◽  
Surface Characterization ◽  
Room Temperature ◽  
Thermal Evaporation ◽  
Xrd Analysis ◽  
Force Microscopy ◽  
Atomic Force ◽  
Average Grain Size ◽  
20 Nm

Thin films of pure silver were deposited on glass substrate by thermal evaporation process at room temperature. Surface characterization of the films was performed using X-ray diffraction (XRD) and atomic force microscopy (AFM). Thickness of the films varied between 20 nm and 72.8 nm. XRD analysis provided a sharp peak at 38.75° from silver. These results indicated that the films deposited on glass substrates at room temperature are crystalline. Three-dimension and top view pictures of the films were obtained by AFM to study the grain size and its dependency on various factors. Average grain size increased with the thickness of the deposited films. A minimum grain size of 8 nm was obtained for 20 nm thick films, reaching 41.9 nm when the film size reaches 60 nm. Grain size was calculated from the information provided by the XRD spectrum and averaging method. We could not find any sequential variation in the grain size with the growth rate.

Transport Properties of B-, P-Doped and Undoped 50 kHz PECVD Microcrystalline Silicon

1989 ◽  
Vol 164 ◽  
Author(s):  
M.A. Hachicha ◽  
Etienne Bustarret
Keyword(s):  
Grain Size ◽  
Hall Mobility ◽  
Solid Phase ◽  
Grazing Angle ◽  
Dc Conductivity ◽  
X Ray Diffraction ◽  
Crystalline Fraction ◽  
Average Grain Size ◽  
20 Nm ◽  
Solid Phase Density

AbstractUndoped 500 nm-thick silicon layers with a crystalline fraction around 95% and an average grain size of 20 nm have been deposited at 350°C by 50 kHz triode PECVD in a H2/SiH4 mixture, in the presence of a magnetic field. Their room temperature (rt) dc conductivity μrt is 0.03 Δ−1cm−1 for a Hall mobility of 0.8 cm 2V−1s−1.The study by SIMS, infrared absorption, grazing angle x-ray diffraction and Raman scattering spectroscopies of the doped samples shows how the crystalline fraction and the grain size drop as the B2H6/SiH4 and PH3/SiH4 volumic ratios increase from 10 ppm to 1%.The rt dc conductivity reaches 2 Δ−1 cm−1 (Hall mobility: 15 cm2V−ls−1) for a solid phase density of 1019 cm−3 boron atoms, and 30 Δ−1cm−1 (Hall mobility: 55 cm2V−ls−1) at the maximum P incorporation of 8 × 1020cm−3.

scholarly journals Material Characterization of a Magnetorheological Fluid Subjected to Long-Term Operation in Damper

Materials ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2195 ◽  
Author(s):  
Dewi Utami ◽  
Ubaidillah ◽  
Saiful Mazlan ◽  
Fitrian Imaduddin ◽  
Nur Nordin ◽  
...  
Keyword(s):  
Dynamic Testing ◽  
Testing Machine ◽  
Morphological Observation ◽  
Magnetic Flux Density ◽  
Damping Force ◽  
Stroke Length ◽  
Mr Fluid ◽  
Term Operation ◽  
Operating Cycles

This paper investigates the field-dependent rheological properties of magnetorheological (MR) fluid used to fill in MR dampers after long-term cyclic operation. For testing purposes, a meandering MR valve was customized to create a double-ended MR damper in which MR fluid flowed inside the valve due to the magnetic flux density. The test was conducted for 170,000 cycles using a fatigue dynamic testing machine which has 20 mm of stroke length and 0.4 Hz of frequency. Firstly, the damping force was investigated as the number of operating cycles increased. Secondly, the change in viscosity of the MR fluid was identified as in-use thickening (IUT). Finally, the morphological observation of MR particles was undertaken before and after the long-term operation. From these tests, it was demonstrated that the damping force increased as the number of operating cycles increases, both when the damper is turn on (on-state) and off (off-state). It is also observed that the particle size and shape changed due to the long operation, showing irregular particles.

scholarly journals Investigation of Primary Recrystallization and Decarbonization with Different Heating Rates of Intermediate Annealing Using Nb-Containing Grain-Oriented Silicon Steel

Metals ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1655
Author(s):  
Xin Tian ◽  
Shuang Kuang ◽  
Jie Li ◽  
Jing Guo ◽  
Yunli Feng
Keyword(s):  
Heating Rate ◽  
Electron Backscatter Diffraction ◽  
Optical Microscope ◽  
Primary Recrystallization ◽  
Silicon Steel ◽  
Intermediate Annealing ◽  
Heating Rates ◽  
Average Grain Size ◽  
The Matrix ◽  
20 Nm

An Nb-containing grain-oriented silicon steel was produced through double-stage cold rolling in order to investigate the effect of the heating rate during intermediate annealing on primary recrystallization and decarburization behavior. The microstructure and texture were observed and analyzed by an optical microscope and an electron backscatter diffraction system. A transmission electron microscope was used to observe the precipitation behavior of inhibitors. The decarburization effect during intermediate annealing was also calculated and discussed. The results show that primary recrystallization takes place after intermediate annealing. As the heating rate increases, the average grain size decreases gradually. The textures of {411}<148> and {111}<112> were found to be the strongest along the thickness direction in all of the annealed specimens and are mainly surrounded by HEGB and HAGB (> 45°). A large number of inhibitors with the size of 14~20 nm precipitate are distributed evenly in the matrix. The above results indicate that the higher heating rate during intermediate annealing contributes to both an excellent microstructure and magnetic properties. From the calculation, as the heating rate increases, decarbonization tends to proceed in the insulation stage, and the total amount of carbonization declines.

Study on Microstructure and Property of the SHS Welding Joint

2012 ◽  
Vol 590 ◽  
pp. 51-55
Author(s):  
Hui Yang ◽  
Guo Dong Zhang ◽  
Yuan Mei Fei
Keyword(s):  
Base Metal ◽  
Large Scale ◽  
Welded Joint ◽  
Automatic Measurement ◽  
Weld Interface ◽  
Hardness Tester ◽  
Metallurgical Bonding ◽  
Structure Morphology ◽  
Digital Microscope ◽  
Welding Metal

With the self-designed welding powder formula,this experiment employed the SHS reaction to weld the base metal,which was steel Q235 here,then respectively used Olympus large-scale horizontal digital microscope to analyze the structure morphology of the welding seam's different regions,JEOL SEM to point-analyze and line-analyze elements' distribution near the the weld interface and HV-1000 CCD automatic measurement microscopic vickers hardness tester to measure the microhardness of the pure copper's welding seam.The experiment's result shows the hardness of different part of the welded joint varies largely,and that the join of alloy elements can increase the microhardness of the welding metal,and that the welding metal and base metal interdiffuse,grow and mix remarkably near the fusion line,realizing wonderful metallurgical bonding.

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