Mechanical Alloying Effect of Hematite and Graphite

2004 ◽  
Vol 449-452 ◽  
pp. 257-260 ◽  
Author(s):  
Chung Hyo Lee ◽  
S.H. Lee ◽  
S.Y. Chun ◽  
Sang J. Lee ◽  
Joo Sun Kim
Keyword(s):  
Solid State ◽  
Mechanical Alloying ◽  
Saturation Magnetization ◽  
Ball Mill ◽  
Room Temperature ◽  
Milling Time ◽  
Mechanochemical Reaction ◽  
Alloying Effect ◽  
State Reduction ◽  
Solid State Reduction

The mechanochemical reaction of hematite with graphite by mechanical alloying (MA) has been investigated at room temperature. The solid state reduction of hematite to Fe3O4 and FeO has been observed after 120 hours of MA by a planetary ball mill. Saturation magnetization is gradually increased with milling time up to 80 h, and then deceased after 120 h of MA, indicating the transformation of Fe3O4 into nonmagnetic FeO through further reduction. Neither the solid state reduction of Fe2O3 by graphite nor a sizable grain refinement is observed in the MA process using a horizontal ball mill.

Nanocomposite Formation in the Fe2O3-M (M=Al, Ti, Zn, Cu) Systems by Mechanical Alloying

2004 ◽  
Vol 449-452 ◽  
pp. 253-256 ◽  
Author(s):  
Chung Hyo Lee ◽  
S.H. Lee ◽  
S.Y. Chun ◽  
Sang Jin Lee ◽  
Young Soon Kwon
Keyword(s):  
Solid State ◽  
Mechanical Alloying ◽  
Saturation Magnetization ◽  
Room Temperature ◽  
Oxide Systems ◽  
State Reduction ◽  
Metal Metal ◽  
Pure Metals ◽  
Solid State Reduction ◽  
Nanocomposite Powders

Nanocomposite formation of metal-metal oxide systems by mechanical alloying (MA) has been investigated at room temperature. The systems we chose are the Fe2O3-M(M=Al,Ti,Zn,Cu), where pure metals are used as reducing agent. It is found that nanocomposite powders in which Al2O3and TiO2are dispersed in Fe matrix with nano-sized grains are obtained by mechanical alloying Fe2O3with Al and Ti, respectively. However, the reduction of Fe2O3with Cu by MA is not occurred. And the system of Fe2O3-Zn results in the formation of FeO plus ZnO after 120 h of milling. It is also shown that the magnetic evidence for the solid state reduction by mechanical alloying through changes in saturation magnetization and coercivity.

Nanocrystalline Formation and Magnetic Properties in Fe2O3–C System by Mechanical Alloying

2021 ◽  
Vol 21 (7) ◽  
pp. 3791-3794
Author(s):  
Chung-Hyo Lee
Keyword(s):  
Heat Treatment ◽  
Solid State ◽  
Mechanical Alloying ◽  
Saturation Magnetization ◽  
Two Phase ◽  
Reaction Heat ◽  
State Reduction ◽  
Heat Treated ◽  
Average Grain Size ◽  
Solid State Reduction

The effect of mechanical alloying (MA) on the solid state reaction of hematite and graphite system with a positive reaction heat was investigated using a mixture of elemental Fe2O3–C powders. The solid state reduction of hematite to Fe3O4 has been obviously observed after 3 hours of MA by a vibrating ball mill. A two-phase mixture of Fe3O4 and remaining Fe2O3 is obtained after 5 hours of MA. Saturation magnetization gradually increases with MA time due to the formation of Fe3O4 and then reaches 23 emu/g after 5 hours of MA. In addition, a Fe3O4 single phase is obtained by MA after 3 hours and subsequently heat treated up to 700°C. X-ray diffraction result shows that the average grain size of Fe3O4 prepared by MA for 5 hours and heat treatment to be in the range of 92 nm. The saturation magnetization of Fe3O4 prepared by MA and heat treatment reaches a maximum value of 56 emu/g for 5 hours MA sample. It is also observed that the coercivity of 5 hours MA sample annealed at 700 °C is still high value of 113 Oe, suggesting that the grain growth of magnetite phase during annealing process tends to be suppressed.

scholarly journals Spatially resolved solid-state reduction of graphene oxide thin films

2018 ◽  
Vol 5 (6) ◽  
pp. 1176-1184 ◽  
Author(s):  
Maria C. Morant-Miñana ◽  
Jonas Heidler ◽  
Gunnar Glasser ◽  
Hao Lu ◽  
Rüdiger Berger ◽  
...  
Keyword(s):  
Thin Films ◽  
Graphene Oxide ◽  
Solid State ◽  
Spatial Resolution ◽  
Room Temperature ◽  
Oxide Thin Films ◽  
State Reduction ◽  
Spatially Resolved ◽  
Solid State Reduction

Controlled reduction of GO thin-films at room temperature with spatial resolution simply by application of a voltage, without the intentional use of electrolytes, has been demonstrated.

Fabrication and Characterization of Magnetic Nanocomposite Powders in Hematite-Ca System by Mechanical Alloying

2017 ◽  
Vol 753 ◽  
pp. 78-83
Author(s):  
Chung Hyo Lee
Keyword(s):  
Grain Size ◽  
Mechanical Alloying ◽  
Ball Milling ◽  
Milling Time ◽  
Magnetic Nanocomposite ◽  
State Reduction ◽  
Treatment Conditions ◽  
Average Grain Size ◽  
Solid State Reduction ◽  
Nanocomposite Powders

We have applied mechanical alloying technique to produce magnetic nanocomposite material using a mixture of Fe2O3 and Ca powders at room temperature. An optimal ball milling and heat treatment conditions to obtain magnetic α-Fe/CaO composite with fine microstructure were investigated by X-ray diffraction, scanning electron microscope and vibrating sample magnetometer measurements. We have revealed that the magnetic α-Fe /CaO nanocomposite powders can be produced by solid state reduction during ball milling. It is found that α-Fe/CaO nanocomposite powders in which CaO is dispersed in α-Fe matrix with a grain size of 45 nm are obtained by mechanical alloying of Fe2O3 with Ca for 5 hours. The saturation magnetization of ball-milled powders increases with increasing milling time and reaches to a maximum value of 65 emu/g after 7 hours of MA. The average grain size of a-Fe in 5 hours MA powders estimated by diffraction line-width are gradually decreased with increasing milling time, and tend to reach at 45 nm. The magnetic hardening due to the reduction of the α-Fe grain size by MA is also observed.

scholarly journals SOLID STATE REDUCTION OF MoO3 WITH CARBON VIA MECHANICAL ALLOYING TO SYNTHESIZE NANO-CRYSTALINE MoO2

2012 ◽  
Vol 05 ◽  
pp. 441-447 ◽  
Author(s):  
M. SAGHAFI ◽  
A. ATAIE ◽  
S. HESHMATI-MANESH
Keyword(s):  
Solid State ◽  
Milling Time ◽  
High Energy ◽  
State Reduction ◽  
Nano Crystalline ◽  
Peak Broadening ◽  
Powder Particles ◽  
Higher Temperature ◽  
Diffraction Patterns ◽  
Solid State Reduction

In this research, effect of milling time on solid state reduction of MoO 3 with carbon has been investigated. It was found that mechanical activation of a mixture of MoO 3 and carbon at ambient temperature by high energy ball milling was not able to reduce MoO 3 to metallic molybdenum. MoO 3 was converted to MoO 2 at the first stage of reduction and peaks of the latter phase in X-ray diffraction patterns were detected when the milling time exceeded from 50 hours. The main effect of increased milling time at this stage was decreasing of MoO 3 peak intensities and significant peak broadening due to decrease in size of crystallites. After prolonged milling, MoO 3 was fully reduced to nano-crystalline MoO 2 and its mean crystallite size was calculated using Williamson–Hall technique and found to be 17.5 nm. Thermodynamic investigations also confirm the possibility of reduction of MoO 3 to MoO 2 during the milling operation at room temperature. But, further reduction to metallic molybdenum requires thermal activation at higher temperature near 1100 K. XRD and SEM techniques were employed to evaluate the powder particles characteristics.

scholarly journals Effect of Milling Parameters on the Development of a Nanostructured FCC–TiNb15Mn Alloy via High-Energy Ball Milling

Metals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1225
Author(s):  
Cristina García-Garrido ◽  
Ranier Sepúlveda Sepúlveda Ferrer ◽  
Christopher Salvo ◽  
Lucía García-Domínguez ◽  
Luis Pérez-Pozo ◽  
...  
Keyword(s):  
Mechanical Alloying ◽  
Ball Mill ◽  
Milling Time ◽  
High Energy ◽  
Planetary Mill ◽  
Nominal Composition ◽  
Mechanically Alloyed ◽  
Milling Parameters ◽  
Energy Ball ◽  
Full Conversion

In this work, a blend of Ti, Nb, and Mn powders, with a nominal composition of 15 wt.% of Mn, and balanced Ti and Nb wt.%, was selected to be mechanically alloyed by the following two alternative high-energy milling devices: a vibratory 8000D mixer/mill® and a PM400 Retsch® planetary ball mill. Two ball-to-powder ratio (BPR) conditions (10:1 and 20:1) were applied, to study the evolution of the synthesized phases under each of the two mechanical alloying conditions. The main findings observed include the following: (1) the sequence conversion evolved from raw elements to a transitory bcc-TiNbMn alloy, and subsequently to an fcc-TiNb15Mn alloy, independent of the milling conditions; (2) the total full conversion to the fcc-TiNb15Mn alloy was only reached by the planetary mill at a minimum of 12 h of milling time, for either of the BPR employed; (3) the planetary mill produced a non-negligible Fe contamination from the milling media, when the highest BPR and milling time were applied; and (4) the final fcc-TiNb15Mn alloy synthesized presents a nanocrystalline nature and a partial degree of amorphization.

scholarly journals Structure-Phase Transformations in the Course of Solid-State Mechanical Alloying of High-Nitrogen Chromium-Manganese Steels

Metals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 301
Author(s):  
Kirill Lyashkov ◽  
Valery Shabashov ◽  
Andrey Zamatovskii ◽  
Kirill Kozlov ◽  
Natalya Kataeva ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Solid State ◽  
Mechanical Alloying ◽  
Ball Milling ◽  
Ball Mill ◽  
Subsequent Annealing ◽  
High Nitrogen ◽  
Transmission Electron ◽  
Structure Phase ◽  
Manganese Steels

The solid-state mechanical alloying (MA) of high-nitrogen chromium-manganese austenite steel—MA in a planetary ball mill, —was studied by methods of Mössbauer spectroscopy and transmission electron microscopy (TEM). In the capacity of a material for the alloying we used mixtures of the binary Fe–Mn and Fe–Cr alloys with the nitrides CrN (Cr2N) and Mn2N. It is shown that ball milling of the mixtures has led to the occurrence of the α → γ transitions being accompanied by the (i) formation of the solid solutions supersaturated with nitrogen and by (ii) their decomposition with the formation of secondary nitrides. The austenite formed by the ball milling and subsequent annealing at 700–800 °C, was a submicrocrystalline one that contained secondary nano-sized crystalline CrN (Cr2N) nitrides. It has been established that using the nitride Mn2N as nitrogen-containing addition is more preferable for the formation and stabilization of austenite—in the course of the MA and subsequent annealing—because of the formation of the concentration-inhomogeneous regions of γ phase enriched with austenite-forming low-mobile manganese.

scholarly journals Feasibility of nickel extraction from Indian chromite overburden by solid state reduction and smelting route

2020 ◽  
Vol 56 (2) ◽  
pp. 229-235
Author(s):  
P. Ganesh ◽  
Dishwar Kumar ◽  
S. Agrawal ◽  
Mandal Kumar ◽  
N. Sahu ◽  
...  
Keyword(s):  
Solid State ◽  
Horizontal Tube ◽  
Low Grade ◽  
State Reduction ◽  
Nickel Extraction ◽  
Reducing Atmosphere ◽  
Chromite Overburden ◽  
Solid State Reduction ◽  
Horizontal Tube Furnace ◽  
Direct Smelting

The present work demonstrates the extraction of nickel from low-grade chromite overburden by using solid state reduction and direct smelting route. Goethite & Quartz are present as major phases whereas chromite, hematite were identified as minor phases in the mineral. Solid state reduction of pellets were carried out inside a horizontal tube furnace at 1000?C, 1200?C, 1400?C for 30, 60, 90 and 120 minutes respectively with creating reducing atmosphere. Pellets of varying basicity (i.e. 0.5, 0.6, 0.7, 0.8 and 0.9) were used directly in the EAF for smelting studies. Highest percent of nickel (2%) having ~ 91% recovery were obtained in solid state reduction route for pellets which was reduced at 1400?C for 120 minute. Similar recovery (~90%) of nickel was obtained inside the ingot (0.67% Ni ) by using pellets of 0.9 basicity through smelting route. From the present investigation, it could be concluded that the solid state reduction as well as smelting routes are feasible for the recovery of nickel from low grade chromite overburden. The production of nickel pig (low grade ferronickel) could also be feasible by smelting route.

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