High Energy Planetary Ball Mill Research Articles

The Cu Matrix Strengthened by TiH₂-C In-Situ Synthesized via Mechanical Milling and Spark Plasma Sintering.

The present work is focused on the fabrication and the investigation of microstructures of copperbased TiC nanocomposites produced by mechanical milling in a high energy planetary ball mill. TiH₂, carbon and copper powders were used as starting materials in which In-Situ reaction between carbon and TiH₂ occurs to form TiC nanoparticles. The mixture powders of Cu-TiH₂-C were milled for 12 h at 450 rpm in Argon gas. Annealing treatment process at 950 °C for 2 h was applied for as-milled composite powders to enhance In-Situ reaction. The consolidation of composite powders was conducted by spark plasma sintering under uniaxial pressing of 70 MPa. Sintering procedure was done at 950 and 1000 °C for 5 min. The results indicated that as TiC nanoparticles are formed after sintering at 950 °C and the TiC particles are increased up at higher sintering temperature of 1000 °C. Fracture surface of sintered samples shows ductile mode. HR-TEM image showed the crystal size of copper was about 10 nm for sample sintered at 1000 °C. The hardness and relative density of the nanocomposites increase when increasing sintering temperature.

Size and strain induced phase formation and ferromagnetism in reduced TiO2 powders

We investigate the strain evolution, phase formation and ferromagnetism of nanocrystalline TiO2 powders prepared by high energy planetary ball milling technique. Pure TiO2 shows the anatase phases in the structural analysis and more than 0.25 h of milled powder turns into Rutile and Magneli phases. The crystallite size and strain were calculated from the X-ray diffraction pattern using the Williamson-Hall equation and the uniform deformation energy density model. Pure TiO2 exhibits paramagnetic nature, which transforms into ferromagnetic one with a moderate moment 0.15 emu/g for 60 h milled powders at an applied field of 12 kOe. The Micro-Raman analyses show the presence of Magneli phase (Ti3O5) along with a shift in the active Eg(1) band for milled powders. X-ray photoelectron spectroscopy results show an oxygen-deficiency peak at 457.7 eV in milled powders. The electron paramagnetic resonance study shows the evidence of oxygen-deficiency which is clear from the resonance signal at 338 mT in milled powders. Further, the electronic structures are investigated by the spin-polarized plane-wave self-consistent field calculation based on density functional theory (DFT) with generalized gradient approximation (GGA) and Hubbard U corrections. The elastic properties are also calculated for pure, oxygen vacancies TiO2 and pure Magneli phase (Ti3O5) crystal. Our results demonstrate the effects of size and strain engineering on the formation of the Magneli phase due to defect induced oxygen vacancy and show the ferromagnetism in TiO2 nanoparticles, which are important for spintronics and other potential applications.

Li2TiO3 pebble fabrication by freeze granulation & freeze drying method

Lithium titanate (Li2TiO3) ceramic is one of the candidate tritium breeding material for fusion reactor. Li2TiO3 in the form of spherical pebbles are kept inside the canisters of the fusion blanket. Prior to pebble fabrication, Li2TiO3 powder was prepared by using Li2CO3 and TiO2 as precursor materials by solid-state reaction method. To make the powder-fine, they were mixed and milled together inside the high energy planetary ball mill followed by calcination at 1000 °C for 5 h. An experimental setup based on the freeze granulation and freeze-drying method was developed in-house, where the green pebbles of 1.5–2 mm were prepared by dropping Li2TiO3 slurry into liquid nitrogen through the 0.6 mm nozzle opening. The pebble drying was performed by the sublimation process at – 60 °C under vacuum followed by the sintering of green pebbles at 950 °C, 1050 °C, and 1150 °C. Various characterizations of the powder and pebbles were carried out to ascertain its phase purity, surface morphology, porosity, pore-size distribution, etc. The results of those characterizations confirm the single-stage reaction, phase purity, desired dimension of pebbles, and their physical and thermal properties. The details of those characterizations along with the dependence of sintering temperatures with the pore size distribution and bulk density of pebbles are discussed in this paper.

Parameters of crystal and electronic structure and magnetic properties of mechanically alloyed Ni3C cubic carbide

The cubic Ni3.3C carbide has been fabricated by mechanical alloying of elemental Ni powder and the multiwalled carbon nanotubes in a high energy planetary ball mill. Crystal structure of carbide obtained belongs to the defective structure of ZnS sphalerite type according to x-ray diffraction data. Parameters of the electronic structure of Ni3.3C were calculated by linearized muffin-tin orbitals method within the plane-wave approximation using as an input the defined parameters of crystal structure. Magnetic properties, such as temperature and field dependences of the magnetic susceptibility of Ni3.3C have been studied. Based on experimental data obtained by studying the crystal structure and magnetic properties of Ni3.3C, as well as on the basis of calculations of electronic structure parameters, a preferred displacement of the carbon atoms in tetrahedral voids of Ni crystal lattice has revealed.

Mechanochemical synthesis of intermetallic compounds in the system gallium – ruthenium

The interaction of a solid inert metal Ru with liquid active metal Ga during mechanical activation in a high-energy planetary ball mill was studied using the X-ray diffraction and the high resolution scanning electron microscopy with energy dispersive X-ray microanalyses. This paper considers mechanical activation effects on formation of intermetallic compounds GaxRuy and their solubility in concentrated acids. Gallium is a surface-active substance with respect to Ruthenium. Under intensive mechanical treatment, liquid Gallium penetrates into grain boundaries of polycrystalline Ruthenium particles and sharply reduces their strength. Because of severe mechanical deformation, an intensive increase of contact surface between solid and liquid metals observed, which a place of rapid formation of intermetallic compounds. This processing leads to high reactive products of mechanical activation of Ga + Ru. Their interaction with a mixed concentrated hydrochloric and nitric acid allows Ruthenium (~37%) to pass into an acidic solution, forming complex compounds of the HxRuCly type (H2RuCl6).

Crystal structure and magnetic properties study on barium hexaferrite (BHF) and cobalt zinc ferrite (CZF) in composites

The composite of BaFe12O19 (BHF) and CoFe1·75Zn0·25O4 (CZF) with different weight percentages have been synthesized by using the high energy planetary ball mill technique. The obtained powders have been characterized by employing the X-ray diffraction, Field Emission Scanning Electron Microscope, and Energy Dispersive X-ray analysis techniques. The lattice parameters and phase percentage have been obtained by the Rietveld refinement analysis of XRD peaks. The crystallite sizes of BHF are greater than the CZF. The magnetic hysteresis loops have been recorded by using the Vibrating Sample Magnetometer (VSM) for all samples. The magnetic interaction between BHF and CZF in the composite has been investigated by plotting the loop width (ΔH) versus magnetization (M). The shape of these curves between loop width versus magnetization is changed with a different weight percentage of BHF and CZF. The saturation magnetization increases with an increase in the concentration of CZF in the composites. Vegard's law is used for comparing the theoretical and experimental magnetic parameters. The squeezing in hysteresis loop at H = 0 vanishes for (55)% BHF + (45)%CZF sample below 150 K and interesting magnetic interaction between two phases has been observed.

Electrical studies on Na and Sm substituted strontium bismuth titanate (SBTi) ceramics

Single-phase Sodium (Na), Samarium (Sm) substituted Strontium Bismuth Titanate (SNSBTi I-V) ceramics were synthesized by solid-state double sintering approach via high energy planetary ball mill for 20 hours grinding. X-ray diffraction (XRD) study confirms the primary structure and orthorhombic distortion of crystal. Scanning electron microscopy (SEM) shows the grain orientation and densified plate-like grain structure of SNSBTi I-V. The complex impedance spectroscopy method was used to study the temperature and frequency dependent electric properties of the material using a high-frequency LCR meter. Z'' versus frequency plots have shown the peak shifting to higher frequencies with increasing concentration of Na, Sm. It is also found that the magnitude of the peaks decreases with increasing temperature. The grain and grain boundary relaxation mechanisms of SNSBTi I-V have been identified using Nyquist plots; the resistance, capacitance and relaxation times were obtained from Z-view software. It is seen that the grain and grain boundary resistances decreased with the increasing concentration of Na and Sm of SBTi ceramics.

Separating the reaction and spark plasma sintering effects during the formation of TiC–Cu composites from mechanically milled Ti–C–3Cu mixtures

The goal of this work was to separate the reaction and spark plasma sintering (SPS) effects during the in-situ synthesis of TiC in mechanically milled Ti–C–3Cu powder mixtures. The powders were milled for 3–10 min in a high-energy planetary ball mill. Structural changes occurring in the reaction mixtures during thermal explosion (TE) in a furnace and SPS in a graphite die were compared. Although the maximum temperature of TE reached the melting point of copper in some samples, no evidence of extensive melting was observed in the microstructure of the products of TE. The ignition and maximum temperatures of TE were found to decrease with increasing milling time of the mixture. In the mixture milled for 10 min, the maximum temperature of TE was only 820 °C. Melting of copper at the inter-particle contacts during SPS was observed in samples milled for 5–10 min (SPS at 900–980 °C) and caused the formation of TiC-depleted regions in the microstructure. Those regions were the re-solidified melt partially filling the pores between the agglomerates. Based on the analysis of the TE parameters in the mixtures and microstructures of the products of TE and SPS, melting during SPS was attributed to the effect of electric current (a high electric current density at the inter-particle contacts) and not to the heat of reaction. The hardness, compressive strength and Young's modulus of the sintered composites are reported. A TiC–Cu composite (milling time 5 min, SPS at 980 °C, relative density 93%) shows a compressive yield strength of 890 MPa and an ultimate compressive strength of 920 MPa.

Microstructure, Magnetic and Mössbauer Studies of Mechanically Alloyed FeCoNi Nanocrystalline Powders

Magnetic structures have attracted a great interest due to their multiple applications, from physics to biomedicine. Iron, nickel and cobalt are among the most important ferromagnetic elements, therefore the synthesis of Fe-based alloys processed by ball milling from the Fe, Ni and Co powders is of particular interest. This subject mainly concerned the structural and magnetic properties evolution of Fe50Co25Ni25 nanocrystalline powder mixture prepared by mechanical alloying in a high-energy planetary ball mill under argon atmosphere. For extended milling time of 100 h, two nanocrystalline Fe (Co,Ni) (∼ 87 nm) and fcc-Co-rich (∼ 47 nm) phases were identified. This phase transformations, dependent on the alloying time, are related to the increase in dislocations and accumulation of stacking faults. Dislocation density of 1.25 × 1015 m−2 is estimated after 100 h of milling. The milled FeCoNi alloy displays a soft ferromagnetic behavior with single magnetic domain (Hc ∼ 12.5 Oe and Mr/Ms ∼ 0.007 for 100 h milling). Mossbauer analysis gives three main magnetic components: two different components attributed to metallic Fe species located in bcc and fcc Fe–Co–Ni domains and a magnetic component characterized by larger hyperfine fields and isomer shifts typical of Fe3+, Fe2+ species and Fe ions.

Microstructure and property relationship between Al-4.5Cu alloy and Al-4.5Cu-Al2O3 composite developed by mechanical alloying

The present work aims to fabricate an alloy (Al-4.5Cu) and a composite (Al-4.5Cu-Al 2 O 3 ) with the help of the mechanical alloying method. As compared to the high-temperature melting and casting process, mechanical alloying is a solid-state synthesis process, which requires low temperature for the synthesis of alloy and composite through powder metallurgy route. A high energy planetary ball mill mechanically alloy the Al, Cu, and Al 2 O 3 powders for 10 h with 200 revolutions per minute to milled the alloy and composite powder mixture. Then the milled powder mixtures are compacted in a single punch die compaction machine and then sintered at 550 and 660 °C for 1hr. XRD analysis of the sintered alloy and composite predicts the formation of a new phase, i.e., CuAl 2 . A comparative study of density, hardness, and compressive strength values of the alloy with the composite depicts that the un-sintered and sintered composite have better properties (density, hardness, and compressive strength) due to the presence of Al 2 O 3 and CuAl 2 . With increasing the sintering temperature from 550 to 660 °C, the properties further enhanced for both the alloy and composite.

Synthesis and characterization of nano-alumina powder by milling of Al and MnO2 powder mixture

There are extensive study on nano composites because of its outstanding mechanical properties when compared with the monolithic materials. The manufacturing of nano particles presents an increasing interest. There are two basic strategy for the synthesis of nano particles, they are bottom up and top down approach. Nano particles are built atom by atom in the bottom up approach. In the synthesis of nano particles, top down approach is most applied one. In this approach, bulk materials are broken down gradually into smaller sizes until they reach nano size. Ball milling is most widely used method for the top down approch. Ball milling process involves milling of constituent powders in a vial where mechanical deformation and chemical reactions takes place between the powders to form new phase. In the present study, constituent powder mixture of Al (1.845 μm) and MnO2 (0.75 μm) are subjected to high energy planetary ball milling to form new phase which is of nano alumina (Al2O3). Initially, Al and MnO2 powder mixture are taken in the ratio of 1:2.416 by weight for different milling duration of 120 min, 240 min and 360 min. The constant speed of the mill was maintained at 300 rpm. The powder mixture inside the mill subjected to impact force between ball to ball and between ball to wall of the container undergo cyclic deformation, cold welding and fracture ensures the generation of nano alumina particles in the range of 50 nm to 560 nm. The effect of mechanical alloying on the microstructure of the powder mixture have been studied by scanning electron microscope (SEM), X-ray diffraction (XRD) and EDS. Toluene was used during milling appears effective process control agent to avoid severe agglomeration and to enhance milling effect.

Effect of Bi3+ on magnetic properties of nanosized La0.7-xBixSr0.3MnO3

Nanoparticles of La0.7-xBixSr0.3MnO3 (0 ≤ x ≤ 0.40) manganites, prepared by high energy planetary ball mill using the top-down approach, have been subjected to structural and magnetization studies to understand the influence of Bi3+ substitution. In the present work, we compare the properties of nanoparticles of all compositions prepared by milling up to 48 h. The structural analysis carried out on the X-ray diffractograms using Rietveld refinement method suggest that as Bi3+ content increases, the structure changes from rhombohedral (space group R-3c, in hexagonal setting) for × ≤ 0.20 to orthorhombic (space group Pnma) for × ≥ 0.30. We also find that the particle size of ∼ 17 nm observed in × = 0.0 sample, increases to ∼ 40 nm for × = 0.35 sample. It is interesting to note that along with changes in the structure and particle size, we observe a cross-over from ferromagnetism (FM) in × = 0.0 (TC = 370 K) to antiferromagnetism (AFM, for × ≥ 0.40). With increase in Bi3+, FM decreases and AFM evolves in the system. For × = 0.40, no long-range ferromagnetism has been noticed. The observed changes in the structural and physical properties could be attributed to the 6 s lone pair character of Bi3+ ions. In the present work, details of structural analysis and magnetization measurements will be presented and discussed.

Study of resistance of ultra-high molecular weight polyethylene to mechanochemical and radiation exposure

Ultra-high molecular weight polyethylene is a promising composite material to protect against ionizing radiation. The effect of mechanical activation and radiation exposure on the polymer structure has been studied. Mechanical activation of ultra-high molecular weight polyethylene was carried out for 30 s, 1, and 2 min in a high-energy water-cooled planetary ball mill AGO-2, followed by its further investigation using X-ray diffraction, X-ray crystallography, IR spectroscopy, scanning electron microscopy, and differentialscanning calorimetry.

Effect of milling on structure and magnetism of nanocrystalline La0.7-xBixSr0.3MnO3 (x = 0.35, 0.40) manganites

Polycrystalline bulk samples of La0.7-x BixSr0.3MnO3 (x = 0.35 and 0.40) manganites have been subjected to high energy planetary ball milling to prepare nanoparticles by using the top-down approach. A significant drop in the particle size has been observed with an increase in milling time. The high temperature magnetic transitions get broader and suppressed while the low temperature maxima in magnetic susceptibility overshadows the high temperature transition. The field dependent magnetization studies describe the competitive coexistence of antiferromagnetic (AFM) and ferromagnetic (FM) interactions in x = 0.35, whereas for x = 0.40, the magnetic ground state is dominantly AFM. The magnitude of magnetization reduces with milling, which could be explained by core-shell model. Detailed analysis of X-ray diffraction, neutron diffraction, and magnetization studies are presented to understand the role of Bi3+ as well as particle size on structure and magnetism.

Application of discrete element simulation in mechanical activation of boron concentrate

We have studied the change of the specific surface area of the ground powder and the dynamics of balls and powders with several milling parameters such as the ball to powder ratio, the size of balls, the filling ratio, and the rotational speed of the vial in the mechanical activation process of boron concentrate by high-energy planetary ball mill. The results have shown that the ball movement regime for good grinding efficiency of the planetary ball mill is “cascading” or light “cataracting”, and contact forces have a greater effect on the grinding of powders than collision forces. The grinding efficiency is related to the compressive force, the contact force, the kinetic energy of the balls, and the number of contacts, however, the compressive force and contact force seem to have a significant effect. The greater the compression and contact forces, the greater the grinding efficiency of powders.

Leaching of indium and tin from waste LCD by a time-efficient method assisted planetary high energy ball milling

The phenomenon of the long leaching time and low leaching rate is presented in the acid leaching process under the conventional conditions of low reaction temperature and acid concentration. In order to promote leaching rates of indium and tin in waste liquid crystal display, an optimized process combining rapid milling and acid leaching has been proposed, which is more time and energy-efficient, environmentally sound compared with the traditional acid leaching process. Leaching mechanism analysis was conducted to uncover the different leaching behavior of indium and tin. And the external factors affecting the leaching rates of indium and tin were studied to optimize. In this process, the fine powder with a weight ratio of 97.6%, which particle size less than 0.075 mm, was obtained with the optimal milling time of 30 min by rapid grinding in the planetary high energy ball milling. About −0.003 l/s of grinding rate constant was performed in the grinding size fraction from 3 mm to 0.075 mm. The research results indicated that the particle size less than 0.035 mm was agglomerated, and the addition of H2O2 reduced the leaching rate for the particle size less than 0.075 mm. Moreover, 86.3% and 76.1% of indium and tin were leached in a short leaching time of 10 min by using 3 M H2SO4 at 85 °C for particle size range from 0.075 to 0.035 mm, while 96.9% and 85.6%, respectively in 90 min.

Enhancing the electrical conductivity of in-situ reduced graphene oxide-zirconia composites through the control of the processing routine

Graphene oxide (GO) was mixed with 3 mol% yttria tetragonal zirconia polycrystal (3YTZP) using two powder processing routines: a colloidal method in an aqueous solution and a combination of ultrasonication with high-energy planetary ball milling in wet conditions. Highly densified 3YTZP composites with reduced GO (rGO) were consolidated by Spark Plasma Sintering. The in-situ reduction of GO was successfully achieved during the high-temperature sintering process and a detailed study of the restoration of the graphene structure in the sintered composites has been made by Raman spectroscopy. Although no differences between the composites prepared by the two processing methods were found in the distribution of the rGO throughout the 3YTZP matrix for high rGO contents (i.e. the composites with 5 and 10 vol% rGO), a better distribution of the graphene phase was found in the composites with 1 and 2.5 vol% rGO prepared by planetary ball milling. This result, together with a better reduction of the GO in these composites, led to the obtaining of rGO/3YTZP composites with a better behavior in terms of electrical conductivity: an electrical percolation threshold below 2.5 vol% rGO and a high electrical conductivity value (~610 S/m for 10 vol% rGO).

Synthesis and characterization of barium hexaferrite (BaFe12O19) nanoparticles from iron ore waste and their possible application in water treatment

In this work hard magnetic glass ceramics has been fabricated using Egyptian Bahariya oasis ore; which contains not less than 51% of its weight as pure iron. High energy planetary ball mill was used to convert the prepared magnetic sample into nanoparticles. Different mechanical milling times were applied to study its effect on the properties of the produced magnetic glass ceramic. Scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray florescence analysis (XRF), differential thermal analysis (DTA), X-ray diffraction analysis (XRD), Raman spectroscopy and Vibrating sample magnetometer (VSM) analysis techniques were performed to characterize the prepared glass ceramic samples before and after exposing to mechanical milling process. XRD revealed crystallization of barium hexaferrite as major phase with average crystallite size ∼26 nm. Saturation magnetization Ms depicted 21.2 emu/g after 5 hours milling. The produces nanoparticles after 5 hours milling showed a good performance in removal of pollutants like methylene blue and Congo red from water by adsorption.

Mechanical and structural behaviour of TiAlV nanocrystalline elaborated by mechanical milling technique

The aim of this study is to fabricate the Ti50Al40X10 nanostructured alloy (X: V) from pure titanium, aluminium, and vanadium powders by using a high-energy planetary ball mill with increasing milling time from 10 to 80 h. Morphology, structural, and mechanical properties of this alloy were investigated by a SEM, XRD, and nano-indentation testing. The effect of milling time on structural, morphological, and mechanical properties has been investigated. Microstructural characterisation showed a decrease of average particle size during milling time. Crystallite size decreased from 49 to 6.02 nm and lattice strain increased from 0.15% to about 0.89% during mechanical alloying. In addition, the mechanical properties of Ti50Al40V10 nanostructured materials were strongly depended on the microstructure and crystallite size of new phases that appear during mechanical milling. Microhardness of the Ti50Al40V10 alloy increases with milling time from 261 to 738 Hv. These changes could be attributed to the crystallite size and the strain variations during milling.

Mechanical and Tribological Behavior of Mechanically Alloyed Ni-TiC Composites Processed via Spark Plasma Sintering.

Titanium carbide (TiC) reinforced nickel (Ni) matrix composites were processed via mechanical alloying (MA) followed by spark plasma sintering (SPS) process. Mechanical alloying has gained special attention as a powerful non-equilibrium process for fabricating amorphous and nanocrystalline materials, whereas spark plasma sintering (SPS) is a unique technique for processing dense and near net shape bulk alloys with homogenous microstructure. TiC reinforcement varied from 5 to 50 wt.% into nickel matrix to investigate its effect on the microstructure and mechanical behavior of Ni-TiC composites. All Ni-TiC composites powder was mechanically alloyed using planetary high energy ball mill with 400 rpm and ball to powder ratio (BPR) 15:1 for 24 h. Bulk Ni-TiC composites were then sintered via SPS process at 50 MPa pressure and 900–1200 °C temperature. All Ni-TiC composites exhibited higher microhardness and compressive strength than pure nickel due to the presence of homogeneously distributed TiC particles within the nickel matrix, matrix grain refinement, and excellent interfacial bonding between nickel and TiC reinforcement. There is an increase in Ni-TiC composites microhardness with an increase in TiC reinforcement from 5 to 50 wt.%, and it reaches the maximum value of 900 HV for Ni-50TiC composites.