scholarly journals Mechanochemical Synthesis of Nanocrystalline Hydroxyapatite from Ca(H2PO4)2.H2O, CaO, Ca(OH)2, and P2O5 Mixtures

Nanomaterials ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 2232
Author(s):  
Sneha Dinda ◽  
Ajay Bhagavatam ◽  
Husam Alrehaili ◽  
Guru Prasad Dinda
Keyword(s):  
Crystallite Size ◽  
Ball Milling ◽  
Mechanochemical Synthesis ◽  
Lattice Strain ◽  
Milled Powder ◽  
High Energy ◽  
Mechanochemical Reaction ◽  
Reactor Wall ◽  
Powder Mixtures ◽  
Nanocrystalline Hydroxyapatite

This paper reports the progress of the mechanochemical synthesis of nanocrystalline hydroxyapatite (HA) starting from six different powder mixtures containing Ca(H2PO4)2.H2O, CaO, Ca(OH)2, and P2O5. The reaction kinetics of HA phase formation during high-energy ball milling was systematically investigated. The mechanochemical reaction rate of the Ca(H2PO4)2.H2O–Ca(OH)2 powder mixture found to be very fast as the HA phase started to form at around 2 min and finished after 30 min of ball milling. All six powder mixtures were transformed entirely into HA, with the crystallite size between 18.5 and 20.2 nm after 1 h and between 22.5 and 23.9 nm after 2 h of milling. Moreover, the lattice strain was found to be 0.8 ± 0.05% in the 1 h milled powder and 0.6 ± 0.05% in all six powders milled for 2 h. This observation, i.e., coarsening of the HA crystal and gradual decrease of the lattice strain with the increase of milling time, is opposite to the results reported by other researchers. The gradual increase in crystallite size and decrease in lattice strain result from dynamic recovery and recrystallization because of an increase in the local temperature of the powder particles trapped between the balls and ball and reactor wall during the high-energy collision.

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.

Synthesis and Characterization of Nanostructured Tungsten-30 Atomic % Chromium Produced by Mechanical Attrition and Hydrogen Sintering

2015 ◽  
Vol 830-831 ◽  
pp. 59-62
Author(s):  
Anshuman Patra ◽  
Swapan Kumar Karak ◽  
Shyamal Kumar Pabi
Keyword(s):  
Electron Microscopy ◽  
Mechanical Alloying ◽  
Crystallite Size ◽  
Milling Time ◽  
Lattice Strain ◽  
Milled Powder ◽  
High Energy ◽  
Dark Field ◽  
Nanoindentation Test ◽  
Scanning Electron

Nanostructured W70Cr30powders were produced by mechanical alloying (MA) of elemental tungsten (W), Chromium (Cr) powders in a high energy planetary ball-mill using tungsten carbide as grinding media and toluene as a process control agent. The crystallite size and lattice strain of the nanostructured powders at different milling time (0 h to 10 h) was calculated from X-ray diffraction patterns (XRD). The crystallite size of W in W70Cr30powder reduced from 100 μm at 0 h to 32.8 nm at 10 h of milling with increase in lattice strain of 0.43% at 10 h of milling. The lattice parameter of tungsten shows initial expansion of lattice upto 0.56% at 5 h of milling and contraction of lattice upto 0.93% at 10 h of milling. The scanning electron microscopy (SEM) micrograph also revealed mixed morphology of elemental W and Cr powders consist of spherical and elongated particles during mechanical alloying (0 h to 10 h). The dark-field transmission electron microscopy (TEM) observations indicated that the crystallite size (~30 nm) of W in W-Cr alloy in the as-milled powder is in good agreement with calculated crystallite size from XRD. Maximum solid solubility of 4.4 at.% Cr in W was found at 10 h of milling. The dislocation density increases from 6.75 (1016/m2) to 17.56 (1016/m2) with increase in the milling time from 0 h to 20 h. No cracks in the sintered pellets were visible under scanning electron microscope (SEM). Hardness and Elastic Modulus of sintered W70Cr30alloy determined by nanoindentation test are less compared to pure W.

scholarly journals The Synthesis of Aluminum Matrix Composites Reinforced with Fe-Al Intermetallic Compounds by Ball Milling and Consolidation

2021 ◽  
Vol 11 (19) ◽  
pp. 8877
Author(s):  
Roberto Ademar Rodríguez Díaz ◽  
Sergio Rubén Gonzaga Segura ◽  
José Luis Reyes Barragán ◽  
Víctor Ravelero Vázquez ◽  
Arturo Molina Ocampo ◽  
...  
Keyword(s):  
Composite Material ◽  
Crystallite Size ◽  
Ball Milling ◽  
Intermetallic Phase ◽  
Aluminum Matrix ◽  
Mechanochemical Reaction ◽  
Aluminum Matrix Composites ◽  
Sintering Process ◽  
Powder Mixtures ◽  
Uniform Dispersion

In this study, a nano-composite material of a nanostructured Al-based matrix reinforced with Fe40Al intermetallic particles was produced by ball milling. During the non-equilibria processing, the powder mixtures with the compositions of Al-XFe40Al (X = 5, 10, and 15 vol. %) were mechanically milled under a low energy regime. The processed Al-XFe40Al powder mixtures were subjected to uniaxial pressing at room temperature. Afterward, the specimens were subjected to a sintering process under an inert atmosphere. In this thermal treatment, the specimens were annealed at 500 °C for 2 h. The sintering process was performed under an argon atmosphere. The crystallite size of the Al decreased as the milling time advanced. This behavior was observed in the three specimens. During the ball milling stage, the powder mixtures composed of Al-XFe40Al did not experience a mechanochemical reaction that could lead to the generation of secondary phases. The crystallite size of the Al displayed a predominant tendency to decrease during the ball milling process. The microstructure of the consolidated specimens indicated a uniform dispersion of the intermetallic reinforcement phases in the Al matrix. Moreover, according to the Vickers microhardness tests, the hardness varied linearly with the increase in the concentration of the Fe40Al intermetallic phase present in the composite material. The presented graphs indicate that the hardness increased almost linearly with the increasing dislocation density and with the reduction in grain sizes (both occurring during the non-equilibria processing). The microstructural and mechanical properties reported in this paper provide the aluminum matrix composite materials with the ideal conditions to be considered candidates for applications in the automotive and aeronautical industries.

Effect of Boron and Carbon Addition on the Phase Transformations during High-Energy Ball Milling and Subsequent Sintering of Si3N4+B and Si3N4+C Powder Mixtures

2016 ◽  
Vol 869 ◽  
pp. 58-63
Author(s):  
Luiz Otávio Vicentin Maruya ◽  
Bruna Rage Baldone Lara ◽  
Belmira Benedita de Lima ◽  
Vanessa Motta Chad ◽  
Gilberto Carvalho Coelho ◽  
...  
Keyword(s):  
Phase Transformations ◽  
Ball Milling ◽  
Weight Ratio ◽  
High Energy ◽  
Ceramic Composites ◽  
Nitrogen Atmosphere ◽  
Carbon Addition ◽  
Powder Mixtures ◽  
X Ray ◽  
Milled Powders

This study reports on effect of boron and carbon addition on the phase transformations during ball milling and subsequent sintering of Si3N4+B and Si3N4+C powder mixtures. Ball milling at room temperature was conducted using stainless steel vials (225 mL) and balls (19mm diameter), 300 rpm and a bal-to-powder weight ratio of 10:1. The as-milled powders were uniaxially compacted in order to obtain cylinder samples with 10 mm diameter, which were subsequently sintered under nitrogen atmosphere at 1500°C for 1h. Characterization of the as-milled powders and sintered samples was performed by X-ray diffraction, scanning electron microscopy, and energy dispersive spectrometry. Only peaks of Si3N4 were identified in X-ray diffractograms of as-milled Si3N4+B and Si3N4+C powders, suggesting that metastable structures were found during milling. After sintering at 1500°C for 1h, the Si3N4+BN and Si3N4+SiC ceramic composites were formed from the mechanically alloyed Si3N4+B and Si3N4+C powders.

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.

Probing the Effect of High Energy Ball Milling on the Structure and Properties of LiNi1/3Mn1/3Co1/3O2 Cathodes for Li-Ion Batteries

2016 ◽  
Vol 13 (3) ◽  
Author(s):  
Malcolm Stein ◽  
Chien-Fan Chen ◽  
Matthew Mullings ◽  
David Jaime ◽  
Audrey Zaleski ◽  
...  
Keyword(s):  
Particle Size ◽  
Electrochemical Performance ◽  
Crystallite Size ◽  
Ball Milling ◽  
Lithium Ion ◽  
High Energy ◽  
Li Ion Batteries ◽  
Structure And Properties ◽  
Transfer Resistance ◽  
Li Ion

Particle size plays an important role in the electrochemical performance of cathodes for lithium-ion (Li-ion) batteries. High energy planetary ball milling of LiNi1/3Mn1/3Co1/3O2 (NMC) cathode materials was investigated as a route to reduce the particle size and improve the electrochemical performance. The effect of ball milling times, milling speeds, and composition on the structure and properties of NMC cathodes was determined. X-ray diffraction analysis showed that ball milling decreased primary particle (crystallite) size by up to 29%, and the crystallite size was correlated with the milling time and milling speed. Using relatively mild milling conditions that provided an intermediate crystallite size, cathodes with higher capacities, improved rate capabilities, and improved capacity retention were obtained within 14 μm-thick electrode configurations. High milling speeds and long milling times not only resulted in smaller crystallite sizes but also lowered electrochemical performance. Beyond reduction in crystallite size, ball milling was found to increase the interfacial charge transfer resistance, lower the electrical conductivity, and produce aggregates that influenced performance. Computations support that electrolyte diffusivity within the cathode and film thickness play a significant role in the electrode performance. This study shows that cathodes with improved performance are obtained through use of mild ball milling conditions and appropriately designed electrodes that optimize the multiple transport phenomena involved in electrochemical charge storage materials.

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.

AN INVESTIGATION INTO MECHANOCHEMICAL SYNTHESIS OF NANOCRYSTALLINE HEXAFERRITE POWDER

2011 ◽  
Vol 25 (07) ◽  
pp. 987-993
Author(s):  
S. SADEGHI-NIARAKI ◽  
S. A. SEYYED EBRAHIMI ◽  
SH. RAYGAN
Keyword(s):  
Crystallite Size ◽  
Single Phase ◽  
Sol Gel ◽  
Milled Powder ◽  
Particle Morphology ◽  
Average Crystallite Size ◽  
Phase Evolution ◽  
High Energy ◽  
Strontium Hexaferrite ◽  
Electron Microscopes

Nanocrystalline strontium hexaferrite powder has been prepared by a new mechanochemical method in which the single phase hexaferrite was obtained via a sol–gel autocombustion process followed by an intermediate high energy milling step and subsequent annealing. The effects of the intermediate milling on the phase evolution, crystallite size and annealing behavior of the final products were investigated using the X-ray diffraction (XRD) technique. The single phase strontium hexaferrite was obtained at an annealing temperature of 800°C, while this temperature was 1,000°C for the powder synthesized without milling. It could be seen that an intermediate milling accelerates the formation of strontium hexaferrite during the calcination process. The results showed that in the milled powder, the average crystallite size of the ferrite was about 40 nm and much smaller than that of the nonmilled powder. Magnetic properties were also measured by a vibrating sample magnetometer (VSM). The particle morphology was then studied by scanning and transmission electron microscopes (SEM and TEM).

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