High Energy Planetary Ball Mill Research Articles

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.

Synthesis and characterization of nanocrystalline high entropy alloy powder

In the present study, non-equiatomic nanocrystalline high entropy alloys (Fe, Al, Cr, Mn, and Ni) powder was synthesized using a high-energy planetary ball mill. During milling, a small amount of powder was collected after a different interval of milling time (2 h, 5 h, 10 h, and 20 h). The milled powders after different milling times were characterized using X-ray diffraction (XRD), and Differential Scanning Calorimetry (DSC). The crystallite size of the milled powder was calculated by analyzing XRD results using the Williamson-Hall method. XRD analysis exhibits that the crystallite size of 20 h milled powder particles is in the nano regime. Besides, lattice parameter, micro-strain and dislocation density of the milled powders were calculated. The melting point of milled powder was analyzed using DSC. The characterization of milled powder suggests the successful formation of nanocrystalline high entropy alloys powder using high-energy ball milling.

A study on factors affecting the densification ofspark plasma sintered ball milled 40 wt% Ni-Fe nanopowder

Using High Energy ball milling, the particle size of average 80 µm and 25 µm, 40 wt% Ni-Fe alloy powder was produced by mechanical alloying respectively. For different time intervals of 16, 32 and 64 hrs, at room temperature, high energy planetary ball milling was done. On “DR.SINTER.LABTM (SPS 5155) machine” spark plasma sintering (SPS) was performed. At constant temperature and pressure of 650 °C and 30Mpa respectively, all samples were sintered. The research is applied on same alloy, as milling hour increases, porosity increases and densification decreases of the samples, this is because of some reasons that are “increase in the surface area of the milled nanopowder (i.e. Reduction of particle size), low green body density of long milling powders by agglomeration of powders and oxidation of powders during a milling process”. As milling hour increases, for perfect densification, more temperature and pressure is needed. In 16 h of milling 85.4% densification was achieved.

Mechanochemical conversion kinetics of red to black phosphorus and scaling parameters for high volume synthesis

Adopting black phosphorus (BP) as a material in electronic and optoelectronic device manufacturing requires the development and understanding of a large-scale synthesis technique. To that end, high-energy planetary ball milling is demonstrated as a scalable synthesis route, and the mechanisms and conversion kinetics of the BP phase transformation are investigated. During the milling process, media collisions rapidly compress amorphous red phosphorus (RP) into crystalline, orthorhombic BP flakes, resulting in a conversion yield of ≈90% for ≈5 g of bulk BP powder. Milling conversion kinetics, monitored via ex situ x-ray diffraction, manifest a sigmoidal behavior best described by the Avrami rate model with each impact of sufficient energy (>25 mJ) producing BP nuclei; the process appears to be limited by grain growth. Using a kinematic model for ball trajectories and impact energies, the optimum milling condition is determined to be an impact energy near ≈25 mJ and a milling dose near ≈100 kJ/gram. Photoexcitation of exfoliated BP flakes reveals emission in the near-infrared, indicating the formation of few-layer BP, a promising advance for optoelectronic device applications.

Synthesis and Characterization of Nanocrystalline Ni-Cr-Al Alloy Powder

The present study primarily focuses on the synthesis of nanocrystalline (NC) Ni-10Cr-10Al (wt%) alloy powder using a high energy ball mill. The composition of Ni-10Cr-10Al alloy was selected in such a way that the complete Al 2 O 3 layer would form on the outer surface of the NC Ni-Cr-Al alloy at high temperatures. For the synthesis of nanocrystalline alloy, powder metallurgy route was preferred in which the as-received powders of required composition were milled using planetary high energy ball milling for 20 h. The milled powders were collected from the mill at milling time of 0 h, 2 h, 5 h, 10 h, 15 h, and 20 h for studying the effect of milling on the powder. The milled powder was characterized using X-ray diffraction (XRD) and Differential Scanning Calorimetry (DSC). The crystallite size was calculated using the Williamson-Hall method and found to be near about 21 nm. Also, the effect of milling on the lattice parameter, micro-strain, dislocation density developed in the milled powder was analyzed using the XRD results. DSC was used to estimate the melting temperature of Ni-10Cr-10Al alloy. The characterization of milled powder suggests the successful formation of NC Ni-10Cr-10Al alloy powder using high-energy ball milling.

Enhancement of cooling rate using nanofluid and hybrid nanofluid in cooling hot titanium plate

Ceramic based nanoparticles are having great potential to improve the thermo physical properties of nanofluids for heat transfer applications. Hot Titanium grade-9 (Ti3Al2.5V) plate is quenched in two different fluids, namely aluminium oxide (Al2O3)/water nanofluid (NF) and aluminium oxide - titanium oxide (Al2O3-TiO2)/water hybrid nanofluid [HyNF] to remove high heat flux. The performance of nanofluids was analyzed through cooling rate determination. High energy planetary ball milling technique was used to prepare Al2O3 and TiO2 nanoparticles. A K-type thermocouple was embedded on the bottom surface of the plate to measure the temperature. The time–temperature data were recorded by the help of a data acquisition system. Experimental results revealed that the nanofluid as well as hybrid nanofluid surprisingly enhanced the cooling efficiency of titanium plate. Al2O3-TiO2/water hybrid nanofluid shows significantly higher value of cooling rate (around 15%) as compared to the conventional cooling fluids. Also hybrid nanofluid exhibit marginally higher efficiency compared to Al2O3/water nanofluid.

Mn2+- doped Zn2SnO4 green phosphor for WLED applications

Eco-friendly phosphors based on non-rare-earth elements have received increasing interest in the field of fabricating white light-emitting diodes (WLEDs). In this work, Mn2+- activated Zn2SnO4 green phosphors were synthesized by high energy planetary ball milling followed by annealing at 1000 °C in a reducing gas environment. The effects of the annealing temperature and the Mn2+ doping concentration on the structural and optical properties were studied. Photoluminescence spectrum displays a green emission band peaking at 523 nm with full width at half maximum of about 32 nm, which is assigned to the spin forbidden d-d transition (4T1(4G) → 6A1(6S)) of the Mn2+ ions. The photoluminescence excitation spectrum of Zn2SnO4:5%Mn2+, monitored at 523 nm, presents five distinct peaks at 359, 380, 424, 435, and 444 nm, which are in good agreement with Mn2+ absorption transitions. The absorption peak at 444 nm well coincides with the peak wavelength of a blue LED emission. By coating the prepared phosphor on a blue LED chip, a green-emitting LED was successfully fabricated. Moreover, a series of white LEDs were made based on 450 nm chip coated with a blend of the Zn2SnO4:5%Mn2+ phosphor with a red phosphor (Zn2SnO4:3%Cr3+,0.6%Al). Warm white light with the correlated color temperature of 3858 K and a high color rendering index of 91 was achieved. These results indicate that the Zn2SnO4:5%Mn2+ phosphor is a promising material for applications in phosphor-converted WLEDs.

Structural Features of High-Entropy HfTaTiNbZr Alloy Fabricated by High-Energy Ball Milling

The HfTaTiNbZr high-entropy alloy (HEA) of equimolar concentration is fabricated from powder components by high-energy ball milling (HEBM) and spark plasma sintering (SPS). The treatment of the initial powders was performed in a planetary high-energy ball mill for 20, 40, 60, and 90 min. It is shown based on the studied surface morphology, microstructure, and phase composition of HEA samples that the multicomponent powder mixture Hf + Ta + Ti + Nb + Zr is subjected to substantial structural variations during HEBM. Starting from X-ray diffraction analysis (XRD) data, it is established that mill treatment for 20 min leads to the formation of a Hf-based solid solution with an fcc structure (Fm3m). Subsequent HEBM for 40 min promotes the formation of a Ta-based solid solution with a bcc structure (Im3m). Peaks of Hf-based and Ta-based solid solutions in the diffraction pattern completely merge after 60-min treatment, forming one common asymmetric peak in an angle range of ~35°–51°. It is revealed that the formation of the HEA with the HfTaTiNbZr composition and bcc structure is observed after 90-min HEBM. The material has a homogeneous structure according to scanning electron microscopy (SEM) data, and the results of energy-dispersive analysis showed that initial elements Hf, Ta, Ti, Nb, and Zr are uniformly distributed in the material bulk. The powders formed after 90-min HEBM are sintered at t = 1150 and 1350°C for 10 min. The results of XRD, SEM, and energy-dispersive spectrometry of SPS-consolidated high-entropy alloys at t = 1350°C show that the material preferentially consists of one phase with the bcc structure and a small amount of Hf2Fe and ZrO. The hardness of the sintered HEA material (10.7 GPa) exceed the hardness of the material consolidated from the mixture of initial elements (6.2 GPa) by a factor 1.8. Density of the samples sintered from initial and HEA powders at t = 1350°C is 9.49 g/cm3 (95.8%) and 9.87 g/cm3 (99.7%), respectively.

The use of pomegranate seed activated by mechanochemical process as a novel adsorbent for the removal of anionic dyestuffs: response surface method approach

This study aims to reveal the potential of using pomegranate seed (PS) as an alternative, new and cost-effective adsorbent for the removal of anionic dyestuffs such as Congo Red (CR) and Remazol Brillant Blue R (RBBR) from aqueous solutions. In addition, the PS was activated by a high-energy planetary ball milling. It was seen that the activated PS (APS) has a higher adsorption capacity and mechanical activation has a positive effect on the adsorption process. The effects of experimental factors were evaluated using both conventional univariate methods and multivariate methods such as response surface methodology (RSM) approach. The effects of experimental factors and possible interactions on both dyestuff removal and adsorption capacity were expressed in mathematical equations. The removal efficiencies over 90% were achieved for both dyestuffs at optimum conditions determined by central composite design (CCD). As a result of isothermic, kinetic, and thermodynamic evaluations, the nature of adsorption was best explained by the Temkin isotherm model and the adsorption mechanism was defined as a chemically controlled, exothermic, and spontaneous reaction. The functional groups and the morphological properties of the adsorbent were determined by Fourier transform infrared spectrophotometry (FTIR) and scanning electron microscopy (SEM) in order to explain the possible interactions between adsorbent and adsorbent molecules.

Effect of milling time on XRD phases and microstructure of a novel Al67Cu20Fe10B3 quasicrystalline alloy

The quasicrystalline materials represent a new materials group with definite crystallite structural characteristics, in which the AlCuFe(B) quasicrystalline alloys have been widely studied owing to its various technological advantages such as easily accessible in nature, thermal stability, affordability as well as not having toxic constituent elements. Although these materials can be achieved by different procedures, the synthesis of more extensive amounts of AlCuFeB quasicrystalline single-phase powders is more complicated. In this study, the Al67Cu20Fe10B3 quasicrystalline alloys were synthesized through the mechanical alloying process and afterward consolidated to the bulk specimens by cold isostatic pressing (CIP) technique. The structural and microstructural evolutions, as well as the morphology of as-milled powders and phase transformations, were studied during the ball milling process using field-emission scanning electron microscopy (FESEM) and x-ray diffractometry (XRD), while the thermal behavior was investigated using differential thermal analysis (DTA). The most fascinated result revealed that the stable AlCuFeB single quasicrystalline phase could be directly synthesized in short milling times (around ∼4 h) by a high-energy planetary ball milling. It was appreciated that the icosahedral phase is stable up to 300 °C, which is misplaced stability at superior temperatures and transforms into crystalline phases. The microhardness of consolidated ball-milled powders at various milling times was determined and it was figured out that the icosahedral phase has an extreme microhardness as much as 10.73 GPa.

“Effect of milling and adding yttrium on sorption characteristics of Zr-Co based nanostructure chemical getter”

Due to recent technological development, requirements, and advances in Hi-Tech systems, the demands for a high vacuum atmosphere and its long-term preservation are important challenges. Chemical getters are appropriate candidates for this goal. In this research, the effect of milling and adding yttrium on getter performance in a Zr-Co based compound was studied. In this research, powder composition with 75%wt Zr and 25%wt Co as a control sample and powder composition with 75%wt Zr, 22% wt Co and 3% wt Y were milled in a high energy planetary ball mill for different times. To activate the getters, they were subjected to heat treatment. According to the vacuum preserving time in different samples, the optimum condition for heat treatment was heating at 360 °C for 80 min. The results showed that the addition of yttrium to the Zr-Co based getter reduced the activation temperature of 70 °C. The vacuum preserving time was evaluated in the range of 0.001–0.1 mmHg. In no getter case, this time was 345 s, and for unmilled and milled Zr75Co25 were 2080 and 3140 s, respectively; and for Zr75Co22Y3 this time was 4955 s. These values highlight the importance of using getter in vacuum systems, emphasize the impact of milling to achieve fine microstructure, as well as the paramount effect of yttrium as a catalyst.

Hydrogenation properties and kinetic study of MgH2 - x wt% AC nanocomposites prepared by ball milling.

The high de-/hydrogenation temperature of magnesium hydride is still a challenge in solid-state hydrogen storage system for automobiles applications. To improve the hydrogenation properties of MgH2, we select activated carbon/charcoal (AC) as a catalyst. A systematic investigation was performed on the hydrogen storage behaviors of MgH2 and MgH2-5wt% AC nanocomposites, which were prepared by a high-energy planetary ball mill. These synthesized nanocomposites were characterized by X-ray diffraction (XRD), high-resolution transmission electron microscope (HRTEM) for phase identification, surface morphology and microstructural analysis. The pressure-composition-temperature (PCT) isotherm investigation shows the maximum hydrogen storage capacity ~ 6.312wt% for MgH2-AC nanocomposites, while 3.417wt% for MgH2 at 300°C. The onset temperature for MgH2-AC nanocomposites is shifted towards lower side than the 50h milled MgH2. The HRTEM study show the activated carbon helps to reduce oxygen from MgO phase in MgH2, so that significantly improvement achieved in the absorption capacity and kinetics also for the MgH2-AC nanocomposites. The presence of β- and γ-phases of MgH2 in MgH2-AC nanocomposites also supports the high hydrogenation properties and with the support of XRD data.

Mechanochemical Processes in the System “Titanium - Heptane” during Ball Milling

The transformations of the solid and liquid phases at high energy planetary ball milling of heptane together with titanium powder were investigated. The sequence of structural heptane transformations using UV-and FT-IR spectroscopy was investigated. Phase constitutions of ball milled titanium powders were studied by X-ray diffraction. It is shown that mechanically induced destruction of heptane occurs by the mechanism of catalytic cracking. The main solid products of the mechanosynthesis were hexagonal (HCP) and cubic (FCC) titanium carbohydrides. Evolution of lattice parameters, crystallite sizes, and micro-stresses of the solid phases during ball milling as a function of the ball milling time have been discussed.

Influences of ball-milled limestone particle sizes and shapes on asphalt mastic stress relaxation behavior

Asphalts often have filler particles added to improve their mechanical properties. Three distinct filler particle fractions were produced by a planetary high-energy ball mill from limestone aggregates (2.36–4.75 mm). Their particle sizes and shapes were studied by binary image processing and related to milling time and aperture size. The relaxation properties of asphalt mastics prepared with fillers of various sizes and shapes were investigated at a constant strain. Insights into the effects of particle size and shape on mastic relaxation behavior were gained by single regression analysis (SRA) in conjunction with grey relational analysis (GRA). The results show that particle size distributions had noticeable local differences in their slopes and spread, while particle shape distributions showed a narrow range of variability for the studied shape descriptors. Based on stress relaxation curves, fine particles were found to cause binders to become stressed more rapidly than coarse particles. Modified mastics showed much faster stress relaxation than corresponding base mastics at stage I, and exhibited higher stable stress levels than base mastics at stage II. A stress relaxation model was established and found to agree well with experimental data, indicating that mastic relaxation properties can be effectively modeled. Furthermore, the SRA coupled with GRA can provide a simple and effective approach to predicting the effects of particle size and shape on mastic relaxation behavior.