Prolonged Ball Milling Research Articles

Stabilizing high solid content slurries for SiC membrane preparation with enhanced separation performances

Silicon carbide (SiC) ceramic membranes are highly sought-after for their exceptional properties including high temperature resistance, corrosion resistance, good hydrophilicity, high flux, and high mechanical strength. However, achieving stable regulation of high solid content SiC slurries for membrane preparation remains a significant challenge. This study presents a novel approach to stabilize the dispersion of high solid content SiC slurries by controlling parameters such as solid content, pH, ball milling time and spray coating parameters. Furthermore, the impact of different milling durations on SiC particle size and membrane performance is systematically investigated, establishing, for the first time, a direct correlation between milling time and particle size. The investigations reveal that prolonged ball milling, specifically 18 h, results in a notable reduction in membrane pore size by approximately 40 %, accompanied by a remarkable enhancement in retention performance, as evidenced by a substantial increase in the average retention rate for 500 nm fluorescent microspheres from 54.61 % to 98.89 %. This study not only offers a practical method for the stable preparation of ceramic slurries, but also provide important reference for membrane morphology control and pore size regulation. These insights hold significant promise for advancing SiC membrane technology in applications such as wastewater treatment and resource recovery.

Influence of processing methods on the strength activity index for sludge as a supplementary cementitious material

Utilizing activated sludge as a partial substitute for cement can both curb cement consumption and address sludge reuse in an economically and environmentally-friendly manner. This study delves into the pozzolanic activity of mechanically-thermal (MT) activated sludge and alkali-mechanical-thermal (AMT) activated sludge, employing the strength activity index (SAI) method. Microscopic insights provided by X-ray diffraction (XRD), scanning electron microscopy (SEM), and laser particle size analysis aid in the interpretation of observed phenomena. The findings underscore the superiority of MT activation over AMT activation, with an SAI of 97 %. Optimal pozzolanic activity is achieved through a 2-hours holding time, slow heating at 10 °C/min, and rapid cooling. A calcination temperature of 800 °C effectively promotes the decomposition of active minerals and enhances the sludge's pozzolanic activity. Additionally, a ball milling time of 2 minutes proves sufficient to meet practical demands, as prolonged ball milling has a limited impact on sludge pozzolanic activity.

Microstructural Transformation and Hydrogen Generation Performance of Magnesium Scrap Ball Milled with Devarda's Alloy.

A method for magnesium scrap transformation into highly efficient hydroreactive material was elaborated. Tested samples were manufactured of magnesium scrap with no additives, or 5 and 10 wt.% Devarda's alloy, by ball milling for 0.5, 1, 2, and 4 h. Their microstructural evolution and reaction kinetics in 3.5 wt.% NaCl solution were investigated. For the samples with additives and of scrap only, microstructural evolution included the formation of large plane-shaped pieces (0.5 and 1 h) with their further transformation into small compacted solid-shaped objects (2 and 4 h), along with accumulation of crystal lattice imperfections favoring pitting corrosion, and magnesium oxidation with residual oxygen under prolonged (4 h) ball milling, resulting in the lowest reactions rates. Modification with Devarda's alloy accelerated microstructural evolution (during 0.5-1 h) and the creation of 'microgalvanic cells', enhancing magnesium galvanic corrosion with hydrogen evolution. The 1 h milled samples, with 5 wt.% Devarda's alloy and without additives, provided the highest hydrogen yields of (95.36 ± 0.38)% and (91.12 ± 1.19)%; maximum reaction rates achieved 470.9 and 143.4 mL/g/min, respectively. Such high results were explained by the combination of the largest specific surface areas, accumulated lattice imperfections, and 'microgalvanic cells' (from additive). The optimal values were 1 h of milling and 5 wt.% of additive.

Development and characterization of a novel Y-Ti-O based aluminum nano-composite processed by high energy ball-milling and spark plasma sintering

The present work reports synthesis and characterization of bulk Y 2 Ti 2 O 7 ‑aluminum nano-composites processed by high energy ball-milling followed by spark plasma sintering. Y-Ti-O based particles were synthesized by mechanical alloying (MA) a 1:2 stoichiometric mixture of Yttrium Oxide (Y 2 O 3 ) and Titanium Oxide (TiO 2 ), and further calcinating the ball-milled mixture at different temperatures. The calcinated powder was further ball-milled for different durations to fabricate the nanoparticles. The X-Ray Diffraction (XRD), Fourier Transform Infra-Red (FTIR) and Raman spectroscopy confirmed the formation of stable Y 2 Ti 2 O 7 . The XRD and Scanning Electron Microscope (SEM) of ball-milled powder reveal crystallite size and particle size of 5 nm and 30 nm, respectively. The XRD data indicates that prolonged ball-milling duration does not deteriorate the structural integrity of the Y 2 Ti 2 O 7 phase. The nano-dispersoids were reinforced in aluminum matrix to obtain dispersion strengthening. The compressive yield strength increased from 60 to 390 MPa by introducing 1 Wt% Y 2 Ti 2 O 7 . • Y 2 Ti 2 O 7 pyrochlore phase was successfully synthesized by ball milling & calcination. • Further ball-milling of calcinated powder has produced Y 2 Ti 2 O 7 nanoparticles of 30 nm. • Prolonged ball milling does not destabilize structural integrity of pyrochlore phase. • Seven times increase in yield strength is observed in Al-Y 2 Ti 2 O 7 nanocomposite.

No ball milling needed: Alternative ODS steel manufacturing with gas atomization reaction synthesis (GARS) and friction-based processing

Oxide dispersion strengthened (ODS) steels are promising structural materials for future fusion reactors. The high-density (∼1023/m3) of highly stable Y-(Ti)-O nano-oxides provide high sink strength for radiation resistance and high-temperature (> 650 °C) creep strength. Concomitantly, helium management is enabled by trapping high density (∼1023/m3) of small (< 3 nm) helium bubbles in the vicinity of nano-oxides. However, conventional route of making ODS steels involves prolonged ball milling, canning, degassing, and laborious thermo-mechanical processing (TMP). Such route, especially the batch-by-batch ball milling step, faces persistent challenge with scalability and high costs. Gas atomization reaction synthesis (GARS) method has demonstrated the potential of making precursor ODS steel powders without ball milling, but the nano-oxide density was around 1021/m3 in the final consolidated form by conventional TMP. Taking advantage of GARS precursor powder, we use friction-based processing, including friction consolidation and extrusion, to manufacture ODS steel with further improved nano-oxide characteristics. Preliminary results showed that Y/Ti/O species were intimately mixed and rapidly reacted to form nano-oxides with a number density of ∼1022/m3.

Microstructure development of Y–Ti–O dispersion strengthened Cu alloys fabricated by mechanical alloying

A Y–Ti–O oxide-dispersion-strengthened (ODS) Cu alloy has been successfully fabricated by mechanical alloying (MA) and spark plasma sintering (SPS). Excessive cold-welding during high energy ball-milling was effectively suppressed by mixing TiO2 and pre-alloyed Cu(Y) powders as the raw powders. Microstructural evolutions during the MA and SPS processes and the subsequent annealing were investigated with a focus on the Y–Ti–O nano-oxides. The 12 h ball-milling failed to achieve super-saturations of Y, Ti, and O in Cu, which led to the in-situ formation of various types of oversized Y/Ti-rich oxides with very irregular morphologies during the SPS. With a prolonged ball-milling of 48 h, the subsequent SPS + annealing processes can promote a high density precipitation of ultra-fine Y–Ti–O nano-oxides. These nano-oxides were further identified as Y2Ti2O7 mostly, with a high degree of coherency in Cu. Fabricating Y–Ti–O ODS-Cu alloys via MA was thus confirmed to be technically feasible, although the dispersion of nano-oxides desires further improvement.

Improvement of hydrogen storage characteristics of catalyst free magnesium nanoparticles prepared by wet milling

Magnesium is one of the potential candidates for on-board hydrogen storage, but slow hydrogenation kinetics and unfavourable thermodynamics limits its practical implementation. To improve the hydrogenation characteristics, nanocrystalline magnesium was prepared by a simple wet milling method without addition of heavy metal catalyst. Compared to micro-crystalline Mg, developed nanocrystalline Mg exhibits improved hydrogen storage properties showing extended plateau region in the pressure-composition-temperature curves with higher hydrogen storage capacity (6.24 wt% at 300°C). Hydrogenation and dehydrogenation kinetics is found to follow Kolmogorov−Johnson−Mehl−Avrami activation energy model confirming the involvement of nucleation-growth-impingement mechanism. Prolonged ball milling leads to quite fast hydrogenation kinetics (upto 90% of the saturation value in 15.5 minutes at 250°C) and leads to substantial decrease in the activation barrier. The activation energy for hydrogenation is found to be 68.88 kJ mol−1 for 8 hours ball milled sample. Present study established a simple and scalable method for nanocrystalline Mg, which can undergo reversible hydrogen absorption and desorption with improved performance without using any additional catalyst.

Effect of alumina source on the densification, phase evolution, and strengthening of sintered mullite-based ceramics from milled coal fly ash

Different alumina sources (Al(OH)3, Al2O3, and boehmite) were used to prepare mullite-based ceramics from milled coal fly ash. The effect of alumina source and sintering temperature on the densification and phase evolution of these ceramics was investigated. Among the three alumina sources, boehmite yielded the greatest densification and crystallization of the ceramics, and an optimal sintering temperature of 1100 °C was identified. The crystallinity and mullite phase increased with increasing boehmite addition, whereas the cristobalite phase decreased. Bulk density and flexural strength values of 2.72 g/cm3 and 155 MPa, respectively, were realized at a boehmite content of 11.8%. The sintered ceramic consisted of mullite and anorthite phases, and was characterized by a crystallinity of 82.8%. Furthermore, particle refinement of raw materials subjected to prolonged ball milling promoted densification and mullitization at relatively low temperatures. The strengthening of the sintered ceramics was attributed to the improved densification, enhanced crystallization, and increased mullite phase. These results will enable the successful reutilization of coal fly ash in the high-strength ceramic tiles.

Artificial neural network technique to predict the properties of multiwall carbon nanotube-fly ash reinforced aluminium composite

In this study, prediction of density and hardness properties using artificial neural network (ANN) and micro structural evolution of multi walled carbon nano tubes (MWCNT) and fly ashes (FA)/Al composites produced by powder metallurgy were investigated. The influence of content (wt.%) of reinforcements(MWCNTs and FA), ball milling time and sintering time on the mechanical properties were experimentally determined by measuring density and hardness values which are the outputs obtained from the artificial neural network. It was found that amount of reinforcements, ball milling time and sintering time play a major role in dispersion and enhancement of the properties. It was also demonstrated that ANN model is a powerful prediction technique to predict the mechanical properties of the composites. Blend powder morphology and sintered composite structure were investigated by scanning electron microscope (SEM). It was found that reinforcements were well dispersed for prolonged ball milling time and sintering time.

Effect of Ball Milling Process on Electrochemical Properties of Copper Hexacyanoferrate Active Material for Calcium-Ion Batteries

This study investigates the electrochemical properties of ball-milled copper hexacyanoferrate (CuHCF), a Prussian blue analogue, as a cathode material in aqueous calcium-ion batteries (CIBs). X-ray diffraction analysis confirmed that the ball milling process did not destroy the crystal structure of the CuHCF active material. The general grain size and crystal surface of the synthesized CuHCF active materials were confirmed from the scanning electron microscopy (SEM) images. The electrochemical test results revealed that prolonged ball milling improved the charge/discharge capacity in the initial cycle. After 200 cycles, structural collapse of the CuHCF electrode occurred, as observed by SEM.

Step annealing and fading studies on EPR signals of Durango apatite for various grain size fractions at the edge of the nano-scale; comparison with the corresponding luminescence results

Durango apatite is a material that exhibits very strong athermal fading (AF) of luminescence signal. In this study, the EPR signals of natural Durango apatite in various different grain dimensions (ball milled for various durations up to 48 h and microscale grain size) were studied. The obtained EPR signal at room temperature yielded three different components with g values 2.0534 (hole center), 2.0398 (hole center) and 1.9920 (electron center). These components were observed for the reference grain size fraction of 100–180 μm; however, prolonged ball milling erases the two hole centers. The behaviour of all obtained components was investigated by step annealing processes (a) between room temperature and 400 °C in steps of 25 °C for 5 min and (b) between 400 °C and 1100 °C, in steps of 100 °C for 1 h. The EPR component with g value 1.9918 was almost totally removed until 1100 °C, while those with g values 2.0534, 2.0398 were erased after annealing at 500 °C and 400 °C respectively. The fading of EPR components was investigated for each ball milling (BM) and microscale grain size independently, at different storage times between 0 and 1000 min. Based on the results of fading and step annealing studies, the EPR component with g value 2.0398 could be directly correlated to the main dosimetric TL trap, while the component with g value 1.9920 appears to be responsible for TA – OSL signal for microscale grain size apatite, corresponding thus to a very deep trap. The behaviour of remnant EPR signal versus storage time could be successfully described by equations based on quantum mechanical tunnelling mechanism.

Processing and characterization of Al-Al3Nb prepared by mechanical alloying and equal channel angular pressing

Mechanically alloyed Al with immiscible elements such as Nb can lead to a uniform distribution of nanoscaled precipitates which are highly stable compared to conventional alloying and with excellent interface, resulting in significant increase in strength without problems associated with nano ceramic particles in metal matrix composites. Although immiscible, Nb can be alloyed with Al through mechanical milling, forming trialuminide (Al3Nb), either directly or upon subsequent precipitation, which possesses high strength, stiffness and stability at elevated temperatures. In the present study, Al-5 at.% Nb supersaturated solid solution was achieved after prolonged ball milling and nano Al3Nb precipitates were formed during subsequent ageing at 530°C. The Al-Al3Nb powder was consolidated by equal channel angular pressing (ECAP) at 400°C, resulting in a fully dense material with a uniform distribution of nanoscaled Al3Nb precipitates in the Al matrix.

Hydration enthalpy of amorphous tricalcium phosphate resulting from partially amorphization of β-tricalcium phosphate

AbstractAs it was recently shown that β-tricalcium phosphate (β-TCP), similar to α-TCP, can be mechanically activated by prolonged ball milling, partially amorphized β-TCP is promising for the development of new bone cement formulations. Hence in the present study the hydration of partially amorphized β-TCP with different contents of an amorphous phase (amorphous tricalcium phosphate, ATCP) was investigated by isothermal calorimetry and quantitative X-ray diffraction (XRD) to obtain the hydration enthalpies of β-TCP and ATCP. Measurements were conducted at 23 °C, a 0.1 M Na

Influence of mechanical milling on structural and magnetic properties of Cu2+ substituted MnFe2O4

Polycrystalline ceramic powders of copper doped manganese ferrite (Mn1−xCuxFe2O4, x = 0.25, 0.50 and 0.75) synthesized by ceramic technique have been subjected to high-energy ball-milling to study the influence of mechanical milling on structural and magnetic properties through X-ray diffraction, scanning electron microscopy, fourier transform infrared spectroscopy and magnetization measurements. The compositional stoichiometry has been ascertained by energy dispersive analysis of X-rays mapping before commencement of high-energy ball milling of the powders. The X-ray diffraction patterns of all as prepared specimens show cubic (fcc) spinel structure with no traces of any impurity of ingredients or unexpected structural phase. The Jahn–Teller (JT) structural distortion evolves after 30 h of prolonged ball milling in all the samples, in fact the tetragonal distortion of the unit cell appears in the sample with x = 0.75 just after 18 h of milling duration. The saturation magnetization at 77 K temperature in the peak field of 5 kOe has been measured for each specimen and the Curie temperatures have been determined through thermal variation of low field (0.5 Oe) AC susceptibility. Infrared spectra also reflect the JT distortion of the unit cell due to ball milling.

Effect of processing conditions on the sliding-wear resistance of ZrC triboceramics fabricated by spark-plasma sintering

The conditions under which ZrC triboceramics are fabricated (high-energy ball-milling and spark-plasma sintering (SPS)) lead to major microstructural differences. The effects of these conditions on the resulting ceramic׳s lubricated sliding-wear resistance were investigated. One condition studied entailed SPS of the as-purchased micrometre powder, giving super-coarse-grained ceramics with little residual porosity. Another was SPS at the same temperature for a shorter time, with the powder having been subjected to short high-energy ball-milling, yielding near-dense, coarse-grained ceramics. The last was with the powder subjected to prolonged high-energy ball-milling, followed by SPS in smother conditions in terms of temperature and time, resulting in fully-dense, fine-grained ceramics. It was found that, while all three were highly wear resistant, the ceramic obtained by combining prolonged ball-milling with smooth SPS was the most so, with less damage and a lower steady-state wear rate coefficient, ascribable to the greater hardness and toughness deriving from the microstructural refinement and densification. The results therefore demonstrate the importance of the processing conditions in obtaining electrically-conductive ZrC triboceramics with superior wear resistance.

Synthesis of columnar carbon nanoscrolls by vibratory milling of expanded graphite

Columnar carbon nanoscrolls are synthesized by vibratory milling of expanded graphite under ambient atmosphere. Different from tubular carbon nanoscrolls, these nanoscrolls are solid and their compactly stacked layers are parallel to one another, with an interlayer spacing of 0.34nm. The columnar structure of the carbon nanoscrolls is independent of their diameters. The formation of this columnar structure can be attributed to the thinness of graphene nanosheets, the elevated temperature, and the vacancies of graphene nanosheets produced by prolonged ball milling.

Effect of structural evolution of aluminum powder during ball milling on hydrogen generation in aluminum–water reaction

Effect of milling time on structure of pure Al powder and consequently on efficiency of Al-water reaction and hydrogen production is studied. Progress in milling process is studied considering changes in morphology, size, lattice imperfections and grains orientation of Al particles. Morphology of particles before and after the reaction is studied to establish a role of size and shape of particles on kinetics of the reaction. It is demonstrated that the formation of interlayer spaces within the investigated Al particles effectively increases hydrogen yield. Moreover, prolonged ball milling eliminates the interlayer spaces and decreases the rate of reaction of water with the powders.

Effect of ball milling on structural and physicochemical characteristics of cassava and Peruvian carrot starches

AbstractPeruvian carrot and cassava starches were ground in a ball mill for 4, 8, 16, and 32 h and their structural and physicochemical characteristics were determined. Results obtained from HPAEC‐PAD, GPC, and amylose content indicated a breaking of hydrogen bounds and α‐(1 → 6) linkages of the starch molecules after treatment. X‐ray diffractograms showed that the milling provided a reduction in the crystalline area of the starch granules. Most of the starch granules displayed agglomeration after 4 h of milling, when observed under a scanning electron microscope, and after 16 h a shapeless mass was observed for Peruvian carrot starch. Solubility and water absorption capacity of the starches increased with an increase in the milling time, while RVA profiles showed a progressive reduction of peak, breakdown, and final viscosities, as well as the development of initial viscosity. Gelatinization temperatures and enthalpies were reduced. Prolonged ball milling accelerated the enthalpy relaxation in both starches. These results confirmed a partial gelatinization of the starches, which was 82.6% for Peruvian carrot and 65.4% for cassava starches after 32 h of milling. The Peruvian carrot starch was more affected by the ball milling because of both its lower amylose content and the defects in its crystalline structure.

A modified method for production of hydrogen from methane

SUMMARY The steam–methane-reformation (SMR) reaction has been modified by including sodium hydroxide in the reaction. It is found that the reaction: 2NaOH+CH4+H2O = Na2CO3+4H2 takes place at much lower temperatures (300–600°C) than the SMR reaction (800–1200°C). The reaction rate is enhanced with a nickel catalyst. We have studied the effect of variously ball-milled nickel on the reaction rate and determined the optimum particle size of the catalyst. Best results were achieved by grinding the catalyst for 2 h. Prolonged ball milling caused the nickel platelets to coalesce and grow in size decreasing the reaction rate. Copyright © 2011 John Wiley & Sons, Ltd.

Evaluation of Characteristics of Interfacial Phases Produced in Al/Ni&amp;lt;sub&amp;gt;3&amp;lt;/sub&amp;gt;Al Composite during Manufacturing

Metal matrix composites (MMCs) are currently being investigated because of their superior properties. The properties are mainly attributed to the efficiency of the load transfer from the matrix to the reinforcements through the matrix-reinforcement interface. The aim of this study is to investigate the effect of manufacturing parameters on the microstructure and morphology of the interface and the aluminide phases formed at the matrix-reinforcement interfaces. The parameters are: milling time to fabricate Ni3Al, method of mixing of Ni3Al and Al powders, compaction pressure and sintering temperature. The composite studied in this research was Al/5 Vol% Ni3Al made from two different types of Ni3Al powders. The results showed that compacting and sintering at higher levels lead to the transformation of Ni3Al particles to thin layers of Al3Ni. It was also shown that the prolonged milling time to produceNi3Alreinforcements and the prolonged ball milling procedure for mixing the powders, both, promote the diffusion process at reinforcement/matrix interface.