Mechanical Activation of Nb75Al Powder Mixtures with Different Process Control Agents

2008 ◽  
Vol 591-593 ◽  
pp. 160-167 ◽  
Author(s):  
Valéria S. Gonçalves ◽  
Cláudio José da Rocha ◽  
Ricardo Mendes Leal Neto
Keyword(s):  
Process Control ◽  
Stearic Acid ◽  
Mechanical Activation ◽  
Milled Powder ◽  
Aggregate Size ◽  
High Energy ◽  
Powder Mixtures ◽  
Powder Charge ◽  
Energy Ball ◽  
Constant Heating

The behavior of different process control agents (PCAs) during mechanical activation of Nb75Al powder mixtures was investigated. Mechanical activation by high-energy ball milling was carried out on a shaker mill (SPEX®8000) for 1 hour. Each PCA (Stearic acid, ethanol and methanol) was added to the powder charge in two proportions (1 and 2 wt%). Shape and microstructure of activated powders (aggregates) were analyzed by scanning electron microscopy. Milled powder mixtures were uniaxially pressed in cylindrical compacts that were further vacuum reacted at a constant heating rate (30°C/min) in order to produce NbAl3 intermetallic compound. The temperature of the samples was monitored by an S-type thermocouple. The results show that the shape and the microstructure of the milled powders were strongly affected by the type and quantity of PCAs, therefore changing the reaction behavior and the densification of the produced pellets. Although ethanol was more effective to control aggregate size, best densification results were attained with 2 wt% of stearic acid.

ROLE OF PROCESS CONTROL AGENT ON MECHANICAL ALLOYING OF NANO STRUCTURED TiAl-BASED ALLOY

2008 ◽  
Vol 22 (18n19) ◽  
pp. 2933-2938 ◽  
Author(s):  
H. BAHMANPOUR ◽  
S. HESHMATI-MANESH
Keyword(s):  
Process Control ◽  
Stearic Acid ◽  
Milled Powder ◽  
High Energy ◽  
Control Agent ◽  
X Ray Diffraction ◽  
Process Control Agent ◽  
Crystallite Sizes ◽  
Energy Ball ◽  
Milled Powders

High energy ball milling was performed on a mixture of titanium and aluminum elemental powders with a composition of Ti -48(at.%) Al . Stearic acid was added to this powder mixture as a process control agent (PCA) to study its effect on the microstructure evolution and crystallite size of the milled powder after various milling times. Phase compositions and morphology of the milled powders were evaluated using X-ray diffraction and scanning electron microscopy. Crystallite sizes of milled powders were determined by Cauchy-Gaussian approach using XRD profiles. It was shown that addition of 1wt.% of stearic acid not only minimizes the adhesion of milling product to the vial and balls, but also reduces its crystallite sizes. It has also a marked effect on the morphology of the final product.

An Investigation of the use of Stearic Acid as a Process Control Agent in High Energy Ball Milling of Nb-Al and Ni-Al Powder Mixtures

2003 ◽  
Vol 416-418 ◽  
pp. 144-149 ◽  
Author(s):  
Cláudio José da Rocha ◽  
Ricardo Mendes Leal Neto ◽  
Valéria S. Gonçalves ◽  
L.L. Carvalho ◽  
Francisco Ambrozio Filho
Keyword(s):  
Process Control ◽  
Stearic Acid ◽  
Ball Milling ◽  
High Energy ◽  
Control Agent ◽  
High Energy Ball Milling ◽  
Process Control Agent ◽  
Powder Mixtures ◽  
Energy Ball ◽  
Al Powder

In Situ Synthesis of TiC-TiB2 Composites via High Energy Ball Milling and Pressureless Sintering

2013 ◽  
Vol 401-403 ◽  
pp. 635-638
Author(s):  
Ping Luo ◽  
Shi Jie Dong ◽  
Zhi Xiong Xie ◽  
Wei Yang ◽  
An Zhuo Yangli
Keyword(s):  
Ball Milling ◽  
Milled Powder ◽  
High Energy ◽  
High Energy Ball Milling ◽  
Sintering Process ◽  
Composite Ceramics ◽  
X Ray Diffraction ◽  
Powder Mixtures ◽  
Energy Ball

TiC-TiB2 composite ceramics were successfully fabricated via planetary ball milling of 72 mass% Ti and 28 mass % B4C powders, followed by low temperature sintering process at 1200°C. The microstructure of the ball-milled powder mixtures and composite ceramics were characterized by Differential thermal analysis equipment (DTA), field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD). The results showed that the ball-milled powder mixtures (Ti and B4C powders) were completely transformed to TiC-TiB2 composite ceramics as the powders were milled for 60 h and sintered at 1200°C for 1 h. The formation mechanism of the TiC-TiB2 composite was discussed. The high energy ball milling and necessary sintering for the powder mixtures plays an important role in the formation of the composites.

An Investigation on the Mechanical Alloying of TiFe Compound by High-Energy Ball Milling

2010 ◽  
Vol 660-661 ◽  
pp. 329-334 ◽  
Author(s):  
Railson Bolsoni Falcão ◽  
Edgar Djalma Campos Carneiro Dammann ◽  
Cláudio José da Rocha ◽  
Ricardo Mendes Leal Neto
Keyword(s):  
Ball Milling ◽  
High Energy ◽  
High Energy Ball Milling ◽  
Low Density Polyethylene ◽  
Low Density ◽  
Powder Mixtures ◽  
Milling Parameters ◽  
Process Route ◽  
Partial Formation ◽  
Energy Ball

This work reports the efforts to obtain TiFe intermetallic compound by high-energy ball milling of Ti and Fe powder mixtures. This process route has been used to provide a better hydrogen intake in this compound. Milling was carried out in a SPEX mill at different times. Strong adherence of material at the vial walls was seen to be the main problem at milling times higher than 1 hour. Attempts to solve this problem were accomplished by adding different process control agents, like ethanol, stearic acid, low density polyethylene, benzene and cyclohexane at variable quantities and keeping constant other milling parameters like ball to powder ration and balls size. Better results were attained with benzene and cyclohexane, but with partial formation of TiFe compound even after a heat treatment (annealing) of the milled samples.

scholarly journals Influence of mechanical activation of AL2O3 on synthesis of magnesium aluminate spinel

2004 ◽  
Vol 36 (2) ◽  
pp. 73-79 ◽  
Author(s):  
Zhang Zhihui ◽  
LI. Nan
Keyword(s):  
Grain Size ◽  
Mechanical Activation ◽  
Bulk Density ◽  
Milling Time ◽  
High Energy ◽  
Magnesium Aluminate ◽  
Reaction Sintering ◽  
Air Atmosphere ◽  
Energy Ball ◽  
Analytical Reagent

Magnesium aluminate (MA) spinel is synthesized by reaction sintering from alumina and magnesia. The effects of mechanical activation of Al2O3 on reaction sintering were investigated. Non-milled a - Al2O3 and a - Al2O3 high-energy ball milled for 12h, 24h and 36h were mixed with a MgO analytical reagent according to the stoichiometric MA ratio, respectively and pressed into billets with diameters of 20mm and height of 15mm. The green-body billets were then sintered at high temperature in an air atmosphere. The results show that bulk density, relative content of MA and grain size of MA increase with increasing high-energy ball milling time of Al2O3. However prolonged milling time over 24h has a small beneficial effect on the densification of MA. Bulk density and grain size of a sample of a- Al2O3 milled for 24h are 3.30g/cm3 and 4-5 mm, respectively.

On sinterability of nanostructured W produced by high-energy ball milling

2007 ◽  
Vol 22 (5) ◽  
pp. 1200-1206 ◽  
Author(s):  
R. Malewar ◽  
K.S. Kumar ◽  
B.S. Murty ◽  
B. Sarma ◽  
S.K. Pabi
Keyword(s):  
Sintered Density ◽  
Sintering Temperature ◽  
High Energy ◽  
Deformation Bands ◽  
Dramatic Decrease ◽  
Powder Charge ◽  
Grinding Media ◽  
Energy Ball ◽  
High Level ◽  
First Time

The present investigation reports for the first time a dramatic decrease in the sintering temperature of elemental W from the conventional temperature of ≥2500 °C to the modest temperature range of 1700–1790 °C by making the W powder nanostructured through high-energy mechanical milling (MM) prior to sintering. The crystallite size of the initial W powder charge with a particle size of 3–4 μm could be brought down to 8 nm by MM for 5 h in WC grinding media. Further milling resulted in a high level of WC contamination, which apparently was due to work hardening and the grain refinement of W. A sintered density as high as 97.4% was achieved by sintering cold, isostatically pressed nanocrystalline (8 nm) W powder at 1790 °C for 900 min. The microstructure of the sintered rods showed the presence of deformation bands, but no cracks, within a large number of W grains. The mechanical properties, when compared with the hardness and elastic modulus, of the sintered nano-W specimen were somewhat superior to those reported for the conventional sintered W.

Structure and Thermal Stability of Nanostructured Iron-doped Zirconia Prepared by High-energy Ball Milling

1999 ◽  
Vol 14 (4) ◽  
pp. 1343-1352 ◽  
Author(s):  
J. Z. Jiang ◽  
F. W. Poulsen ◽  
S. Mørup
Keyword(s):  
Ball Milling ◽  
Unit Cell Volume ◽  
High Energy ◽  
High Energy Ball Milling ◽  
Iron Ions ◽  
Monoclinic Zirconia ◽  
Maximum Solubility ◽  
Powder Mixtures ◽  
Energy Ball ◽  
Thermal Stability Of

Fully stabilized cubic zirconia doped with iron oxide has been synthesized by high-energy ball milling from powder mixtures of monoclinic zirconia and hematite. It is found that the iron ions dissolved in cubic ZrO2 are in substitutional positions with a maximum solubility of approximately 18.5 mol% α–Fe2O3. The unit-cell volume of the cubic ZrO2 phase decreases with increasing iron content. During heating the cubic-to-tetragonal transition occurs at approximately 827 °C and the tetragonal-to-monoclinic transition seems to be absent at temperatures below 950 °C. During cooling the tetragonal-to-monoclinic transition occurs at 900–1100 °C.

Fabrication of Biocompatible β-Ti-Nb-Sn Alloy by Pulsed Current Activated Sintering Using High Energy Ball Milled Powder

2009 ◽  
Vol 1 (2) ◽  
pp. 205-211 ◽  
Author(s):  
Abdel-Nasser Omran ◽  
Kee Do Woo ◽  
Eui Pyo Kwon ◽  
Nasser A. Barakat ◽  
Hyun Bom. Lee ◽  
...  
Keyword(s):  
Milled Powder ◽  
High Energy ◽  
Pulsed Current ◽  
Activated Sintering ◽  
Energy Ball
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