Optimum Milling Time Research Articles

Regulating the surface area increase of zero-valent iron (ZVI) during ball milling: A study of the mechanical mechanism and low-carbon milling

This study investigates the effect of milling parameters on the specific surface area (SSA) increase of zero-valent iron (ZVI) powder, which is crucial for its environmental applications. Combining experimental and orthogonal design methodologies, the research explores how the parameters modulate the SSA. The operational factors are analyzed from the perspectives of bead momentum, kinetic energy, and energy efficiency. A regression model is proposed for the precise fabrication of ZVI with predetermined SSA. Furthermore, the study identifies optimized parameters that minimize energy consumption and carbon emissions. The results suggest that the optimal milling time is 10 min, with larger beads (2.0 mm), higher quality beads (0.75 kg), and higher shaft rotational speed (2000 rpm) significantly enhancing SSA. Discrete Element Method (DEM) simulations reveal micro-mechanical interactions, supporting the parameter selection scheme for maximizing SSA. The findings contribute to optimizing the milling process of the ductile ZVI powder for environmental clean-up.

Wood waste ash as sole solid precursor in a novel alkali-activated material: Influence of the ash particle size

Wood waste ash (WWA) was utilized as sole solid precursor in alkali-activated material (AAM) with NaOH as alkaline activator. WWA was milled at different times (15–30-60–120-180–240-300–360-600 min) to obtain the optimum milling time. Characterization results showed that WWA was mainly composed of SiO2 (68.6 wt%); XRD identified amorphous phase, quartz, and calcite; and volume moment mean diameter (D[4,3]) was 9.97 µm after 240 milling minutes. XRD/FTIR of pastes showed that WWA reacted with NaOH, chemical shrinkage concluded that occurred formation of expansive reaction products, and SEM/EDS identified poorly compacted and layered Na-Si reaction products. Compressive strength of mortars reached 17.0 ± 0.8 MPa (3 days at 65 °C) and 5.0 ± 0.2 MPa (7 days at 25 °C). Highest reaction development and strength were obtained for AAM produced with WWA milled for 240 min.

Obtaining ultra-high hardness in spark plasma sintered Ge40As40Se20 bulk glass

In order to overcome the narrow glass-forming compositional range with traditional melt-quenching method, we here performed the mechanical milling and Spark Plasma Sintering technology to fabricate a high Ge content chalcogenide glass, the Ge40As40Se20 glass, which locates edge of the Ge-As-Se glass-forming domain. By using the optimal ball milling time of 50 h and sintering stress of 37.5 MPa, the large size Ge40As40Se20 bulk glasses were obtained, which possesses both a large Vickers hardness of 369 kgf/mm2 and a relative high infrared optical transmission of 43 % (@5 and 9 μm). Moreover, it was found there are pores in the sintered glasses more or less, and the pore size and number significantly affect the transmission, i.e., the optimal Ge40As40Se20 bulk glasses were demonstrated has the smallest and least pores via scanning electron microscope. The combination of mechanical milling and low-temperature sintering methods has been confirmed can be used to improve the glass formability and then obtain the high Ge content component with a potential high hardness glass to break through the limited mechanical property of chalcogenides.

Boosting the thermoelectric properties of layered SnSb2Te4 compound by microstructure regulation combined with heterovalent halogen substitution

The layered IVV2Te4-based compounds have recently received significant attention due to their intrinsically low lattice thermal conductivities. However, the influence of microstructure regulation and halogen doping on their thermoelectric properties has been scarcely studied. In this work, we systematically investigated the anisotropic thermoelectric transport properties of pristine SnSb2Te4 compounds with varied microstructures manipulated by ball milling. With the help of thermoelectric transport models, the optimal ball milling time is estimated based on the calculation of quality factor. Furthermore, the remarkably improved Seebeck coefficient is achieved by the introduction of halogen elements into Te sites, which is attributed to reduced carrier concentration and converged carrier pockets. As a result, a maximal zT ∼0.4 at 725 K is achieved in SnSb2(Te0·94I0.06)4 sample aligned with the SPS pressure direction with a ball-milling time of 1 h, which demonstrates a 35 % enhancement over the pristine sample. This work provides an insightful guide to elevate the thermoelectric properties of layered IVVI2Te4-based compounds.

A Study on the Adsorption of Methylene Blue by Acid-Modified Coal Measures Kaolin

In this paper, coal measure kaolin after flotation decarburization was made into an adsorbent by ball milling and acid modification to absorb methylene blue in water, achieving the treatment of waste with waste. The objective of this paper is to expand the application of coal measure kaolin, reduce its stock, and lower the raw material cost of adsorbents while treating wastewater containing methylene blue. The optimum milling time, acid boiling conditions, and adsorption conditions were investigated. Furthermore, the adsorption mechanism was investigated by kinetic calculation. The results show that the optimum milling time is 7 h. Relatively good acid modification conditions include a boiling temperature of 100 °C, a stirring time of 135 min, a stirring speed of 1000 r·min−1, and a concentration of hydrochloric acid of 8 mol·L−1. When 0.05 g of flotation kaolin adsorbent was used to adsorb the solution with pH 12 and a methylene blue concentration of 100 mg·L−1, the optimal adsorption conditions were a 38.05 °C adsorption temperature, a 160 r·min−1 stirring speed, and a 31.02 min stirring time. Under these optimal conditions, the adsorption quantity reached 39.92 mg·g−1. The adsorption process involves physical adsorption and spontaneous adsorption. The adsorption type is known as the quasi-second-order adsorption kinetic model. The adsorption form is heterogeneous adsorption in which a monolayer and a multi-molecular layer coexist.

Influence of Synthesis Parameters on the Short-Range Structure and Electrochemical Performances of Li2MnO2F.

In the last years, disordered rocksalt structure (DRS) materials were proposed as a positive electrode for lithium-ion batteries. In particular, the fluorinated DRS materials were proposed to be more stable upon cycling than pure oxide counterparts. These materials are mainly obtained by mechanosynthesis in order to incorporate a significant number of F ions and maintain a disordered structure. Since the local structural arrangement is crucial for battery application, we aim to monitor its evolution upon the synthesis of Li2MnO2F from two sets of precursors: Mn2O3, Li2O, and LiF or LiMnO2 and LiF. The synthesis progress was thus followed, by 7Li and 19F MAS NMR coupled to XRD to probe the structure at different scales. This allowed us to identify an optimal milling time to reach the final compounds. We show that they exhibit similar morphology (by SEM), medium- and short-range orders (by XRD, 7Li and 19F NMR, EXAFS), and average Mn oxidation degree (by XANES). The electrochemical performances of the two compounds are almost similar, with high specific capacities of 319 mAh·g-1 ("from LiMnO2") and 304 mAh·g-1 ("from Mn2O3") for the first charge to 4.8 V vs Li+/Li, proving their interest as post-NMC candidates as positive electrode materials.

Nanoscale Stolephorus sp. powder fabrication using high-energy milling for bioactive materials in dentistry.

The application of natural products in dentistry has been widely explored. Anchovy (Stolephorus in Latin) has been examined for its bioactive content (calcium, phosphorus and fluoride) as an agent for bone stimulation and tooth development, topical fluoridation and pulp capping. Ball milling has been used to prepare calcium oxide nanoparticles from snakehead fish bone. The aim of the study was to reduce the particle size of Stolephorus sp. powder to the nanoscale using high-energy ball milling for 8, 12 and 24 h, and to analyze the optimal milling time by comparing the powder characteristics. The Stolephorus sp. were oven-dried at 50°C for 6 h, after which the entire fish were crushed into powder. The fish powder was produced by blending the material for 5 min and passing it through a 200-mesh sieve. The remaining dried fish was blended again for 5 min until it passed through the sieve. The top-down approach to the particle size reduction was performed using high-energy milling at 3 distinct time points (8, 12 and 24 h). The characteristics of the powder were evaluated using a particle size analyzer, a Fourier-transform infrared spectrometer (FTIR) and scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS). The Stolephorus sp. powder contained 64.50% protein, 7,420 mg/kg sodium, 28,912 mg/kg calcium, and 1,924 mg/kg magnesium. The high-energy milling process resulted in a reduction of the particle size from the microscale to the nanoscale. The analysis of the average particle size and polydispersity index indicated that 24 h of milling showed the most optimal results. Furthermore, the functional groups exhibited no significant alteration at 3 milling times (p ≥ 0.05, FTIR analysis). The high-energy milling method has the potential to reduce the particle size of Stolephorus sp. powder to the nanoscale at the 8- and 24-h milling periods. The powder resulting from the 24-h milling process had a size of 789.3 ±170.7 nm, smooth size distribution, good size uniformity, a polydispersity index of 0.763, no significant change in organic and inorganic compound content, and a calcium/phosphorus ratio that was the closest to that of hydroxyapatite (HAp).

P/M 18Cr ODS steels produced by mechanical alloying and hot powder forging

Mechanical alloying in attritor mill and powder consolidation through hot forging were employed to produce 18Cr ODS steels. Elemental powders were mechanically alloyed with nano-size yttria powder for up to 12 h. The effect of milling time on powder morphology, crystallite size and lattice strain were studied. Optimum milling time of mechanical alloying was determined for dissolution of constituents in the ferrite matrix. Further milling led to peak broadening. TEM confirmed the presence of fine crystallites in milled powders. HRTEM fringes were taken on the oxide particles. Their FFT confirmed that Y2O3 and TiO2 particles were present in the milled powders. The milled powders were consolidated through hot powder forging. Addition of Ti and Y2O3 significantly reduce the grain size in forged alloys. It also leads to formation of fine complex Y-Ti-O oxides. The powder forged alloys exhibited fine grained recrystallized microstructure. Reasons for this are discussed.

Effect of Milling on Forest Residue-Derived Biochar with High Energy Milling Ellipse 3 Dimension

The research on the synthesis of nanoparticles using the high-energy ball milling method technique is limited in Indonesia. This work aims to reduce the size of the remaining biochar powder from the lignocellulosic residual forest (twig) into a nanoparticle. High-Energy Ball Milling-Ellipse 3 Dimension (HEM-E3D) was used to grind the biochar through 212 um mesh with time variations of 0, 2, 3, and 4 hours. The speed of the HEM-E3D is 180 rpm, while the milling on and off times are 10 minutes and 1 minute, respectively. The Particle Size Analyzer (PSA) characterization data show that 4 hours is the optimal milling time with 282,7 nm and evenly distributed particles. The morphology of powder biochar resemblant sheets and an average size of 205 nm at 60000x magnification. There were no discernible and damaged functional group alterations in the surface functional groups as determined by Fourier Transform Infrared Spectroscopy (FTIR). The adsorption experiment using a thin film method shows that powder biochar could reduce heavy metal concentrations of Cr (VI).

Curcuma particle size evolution by application of bead milling process and curcuminoids content determination

SummaryThe aim of this research was to investigate the effect of curcuma dispersion bead milling on particle size evolution over time. The study of 10 wt.% and 20 wt.% curcuma dispersions revealed that dispersions' polydispersity was decreasing up to 180 min which was found to be the optimum milling time with the volume mean diameter (d4,3) of (11.47 ± 0.85) μm. This diameter was the most effective with respect to the curcuma powder coagulation process attributed to the effect of curcuma oils after the milling time of 180 min. The mechanochemically atomized curcuma was used as a potential source of curcuminoids. By differential scanning calorimetry (DSC), two endothermic peaks were observed and related to curcuma melting effects. Curcumin powder exhibited one broad melting peak at 176 °C. Obtained data indicated that effective mechanochemical treatment makes curcuma powder a highly beneficial supplement applicable in food matrices of the human diet.

Effects of ball milling time on the microstructure and hydrogen storage performances of Ti21.7Y0.3Fe16Mn3Cr alloy

TiFe alloy can store hydrogen at room temperature and low hydrogen pressure, and its theoretical hydrogen storage capacity is up to 1.8 wt%. However, TiFe alloy needs to be activated at high pressure (5 MPa hydrogen) and high temperature (673–723 K), which limits the practical application of TiFe alloy. The as-cast Ti 21.7 Y 0.3 Fe 16 Mn 3 Cr alloy was milled for 0, 0.5, 0.75, 1, and 3 h to study the effects of ball milling on phase structures and hydrogen storage performances. Emphasis was focused on the activation process of as-milled alloys at different temperatures, including the activation process at 483, 443, and 403 K. The results show that the alloys were consisted of TiFe phase, and [Fe, Cr] solid solution. The nanocrystalline boundary produced by milling and the phase boundary provided by the second phase provide a large number of channels for hydrogen diffusion and promote the improvement of hydrogen storage performances. The time required for activation process of as-milled alloys was significantly reduced, and the activation time of as-milled (0.75 h) was only 4 min, and its enthalpy variation for hydrogen absorption and desorption was 22.943 and 26.215 kJ mol −1 H 2 , respectively. • The phase composition and micro-structure of the milled Ti 21.7 Y 0.3 Fe 16 Mn 3 Cr alloy were studied. • Nanocrystalline boundary produced by milling provides many channels for hydrogen diffusion. • Ball milling improves the activation process of the alloy and shortens the activation time. • The optimum milling time of the alloy is 45 min, and its activation time is shortened to 4 min.

Fabrication of silicon carbide ceramics by combination of slip casting and spark plasma sintering

In this work, first, a systematic study has been done to optimize the rheological behavior of silicon carbide (SiC) slurries to produce 20 mm disc-shaped green bodies with the highest relative density by adding sintering aids and changing the most effective parameters of the slip casting process. In the second step, slip-casted SiC green bodies were sintered via spark plasma sintering (SPS) under the same conditions: at a heating rate of 200 °C/min and under a vacuum atmosphere (10−2 Torr), the temperature reached 1900 °C and was maintained for 15 min, then, a pressure of 50 MPa was applied, and sintering was performed for 15 min. Initial powders, as well as green bodies, were well characterized via different methods. Also, the microstructure, physical, and mechanical properties of sintered samples were investigated. Results showed that the optimal concentration of tetramethylammonium hydroxide (TMAH) as a dispersant agent for slurry with 60 wt% of SiC was 2 wt%. In addition, the optimal milling time for slurries containing sintering aids was 24 h. The sintered SiC samples containing a mixture of Al2O3 and Y2O3 powder as a liquid phase sintering aid in a range of 5–10 wt% showed low sinterability and as a result, their microstructures contained pores. In contrast, the use of B4C powder as a solid phase sintering aid in a range of 5–10 wt% resulted in forming of sintered SiC samples with completely uniform and dense structures without visible pores. The optimal percentage of B4C was 7 wt%, and the relative density and the hardness of the corresponding sintered sample were 99.5% and 3300 ± 20 Hv, respectively.

Microstructure and Hydrogen Storage Performance of Ball-Milled MgH2 Catalyzed by FeTi

A high-energy ball-milling method was applied for different milling times (1 h, 3 h, and 10 h) to synthetize nanocrystalline MgH2 powder samples catalyzed by Fe2Ti. Morphology and microstructure of the powders were characterized by scanning electron microscopy and X-ray diffraction. The recorded diffraction profiles were evaluated by the convolutional multiple whole profile fitting algorithm, in order to determine microstructural parameters of the composites, such as average crystallite size and average dislocation density. Differential scanning calorimetry was performed to investigate the dehydrogenation characteristics of the alloys. It was obtained that there exists an optimal milling time (3 h) when desorption occurs at the lowest temperature. X-ray diffraction of partially dehydrided states confirmed a two-step H-release, including the subsequent desorption of γ-MgH2 and α-MgH2. The effect of milling time on the H-sorption performance was investigated in a Sievert-type apparatus. The best overall hydrogenation performance was obtained for the composite milled for 3 h.

Mechanochemical Preparation of a Novel Slow-Release Fertilizer Based on K2SO4-kaolinite

In this study, a novel slow-release fertilizer (SRF) consisting of kaolinite and K2SO4 was prepared, employing the process of mechanochemical milling in a planetary ball mill. To obtain the optimum milling time and speed, several samples were made at fixed mass ratios of kaolinite: K2SO4 (3:1). The milling rotational speed ranged from 200 to 700 rpm for 120 min. Different milling times ranging from 60 to 180 min at fixed 600 rpm milling speed were also investigated to evaluate the incorporation of K2SO4 and to measure the liberation of K+ and SO42− ions into solution. The properties of the studied samples were analyzed by Fourier transformation infrared spectrometry (FTIR), thermal gravimetric analysis (TGA), and ion chromatography (IC). The mechanochemical process is a green chemistry procedure that is successfully applied to incorporate K2SO4 into the amorphous kaolinite structure. The slow-release performance was evaluated by determining the K+ and SO42− content in the aqueous solution upon leaching. The optimum released amount of K+ after 24 h was 32 mg L−1 for the milling conditions of 180 min and 700 rpm, indicating that K2SO4-kaolinite has good slow-release properties. The novel SRF is cost-effective, environmentally friendly, and improves the fertilizer’s efficiency in many agricultural applications.

Effect of ball milling time on microstructure and mechanical properties of graphene nanoplates and TiBw reinforced Ti–6Al–4V alloy composites

Ti–6Al–4V (TC4) matrix composites with graphene nanoplatelets (GNPs) and TiB whiskers (TiBw) were synthesized by ball milling, Fast Hot-Press Sintering (FHPS), and hot rolling (HR) method. The microstructures of the ball-milled powders, the as-sintered and as-rolled composites were characterized by Raman spectroscopy, scanning electron microscopy, and transmission electron microscopy. It revealed that there was an optimal ball milling time existed for obtaining GNPs with uniform dispersion and an acceptable degree of defects. The Raman results indicated that the defects increased and the number of GNPs layers decreased with the increasing ball milling time. Tensile tests revealed that the ultimate tensile strength of the 8-h-ball-milling composites increased from 1098 MPa to 1182 MPa and the elongation only dropped slightly from 16.0% to 15.1% compared with that of TC4 alloy fabricated under the same procedure. The failure mechanism of composites was further discussed by analyzing the fracture surface morphologies. Overall, this study highlights the effect of ball milling time on the structure integrity and dispersion homogeneity of GNPs, which is crucial to make full use of the excellent properties of GNPs in TC4 matrix composites.

Ni-Mn-Al Heusler Alloy Samples Preparation by Mechanical Alloying Method and Study of their Investigated Properties

Objective: In this work, ternary Ni-Mn-Al Heusler alloy powder samples were fabricated using mechanical alloying technique to study its alloy formation mechanism and the effects of mechanical alloying on the investigated properties. Methods: The samples were prepared using high energy planetary ball mill under argon conditions. The milling time of 0 h (hour/hours), 5 h, 10 h and 15 h were selected to see the progress of alloy formation. The microstructural, compositional, thermal and magnetic studies of ball milled powder samples were conducted. Findings: Compositional study reveals stoichiometric Heusler composition (X2YZ) of Ni-Mn-Al alloy with no contamination. The optimum milling time required for the formation of alloy by mechanical alloying resulted through the proper selection of milling parameters. The average crystallite size obtained reveals that nanocrystalline structure of Ni-Mn-Al alloy was achieved during the ball milling operation. The successive heating of powder particles in differential scanning calorimetry showed crystallization and alloy formation. Novelty/Applications: The magnetic study indicated soft ferromagnetic nature of the selected ball milled powder sample suggesting the alloy can be developed for possible ferromagnetic shape memory alloy applications. Keywords: Ni-Mn-Al; Heusler alloy; Mechanical alloying; Ball milling; Structural properties

On the synthesis and sintering behavior of a novel Mg-Ca alloy, Part I: Mechanical alloying

A novel Mg-0.7Ca alloy was prepared by the mechanical alloying (MA) process. Different variables were examined in order to obtain the optimum sample with the best milling behavior and potential sinterability. The structural studies were carried out using X-ray Diffractometer (XRD) and scanning electron microscopy (SEM). Crystallite size and lattice strain of the milled samples were examined by Scherrer and Williamson-Hall methods in order to finalize the investigation.
 The optimum milling time was found to be 60 minutes. In addition, a starch-containing sample with a fraction of 2.5 weight percent seemed to have the best microstructural properties, based on SEM observations and crystallite size assessments. Due discussions about the effective phenomena during the mechanical alloying were also included.

Effect of Ball Milling Technology on Properties of Refractory Waste

With the popularization of "sponge city" in the whole country, the use of permeable bricks is increasing every year. Although the raw materials required for the preparation of permeable bricks are widely sourced, there are few reports on the process of using refractory waste to prepare permeable bricks. It is the ball milling process of refractory waste. The effects of ball milling time, ball mill rotation speed, and ball-to-material ratio on the properties of refractory waste were mainly studied. Through the experimental results and analysis, the following conclusions can be drawn: with the increase of ball milling time, ball milling speed and ball-to-material ratio, the particle size of refractory waste powder gradually decreases. Through research, it is concluded that the optimal ball milling time is 4h, the ball milling speed is 100r/min, and the ball-to-material ratio is 2:1.

Eu-Doped Gd2MoB2O9 Phosphors for Latent Fingerprints Detection

The luminescent powders from rare-earth ions doped oxides have been successfully used for latent fingerprint detection due to high efficiency, high contrast and low background interface. The Gd2MoB2O9:Eu3+ phosphors with varying compositions of Eu3+ions were synthesized by solid state reaction method. These phosphors were investigated by X-ray diffraction (XRD), diffuse reflectance spectroscopy, photoluminescence (PL), and decay curves studies. Multiphoton relaxation decay rate and coupling strength was evaluated using phonon side band spectrum showing 0.4 mol% doped samples show less non radiative decay rate. The 0.40 mol% of Eu3+ ion concentration doped in the Gd2MoB2O9 host lattice show highest photoluminescence emission intensity at 613 nm, in orange red region, monitored at 394 nm excitation. The Gd2MoB2O9:Eu3+ phosphors samples were optimized to 900 °C sintering temperature and optimum milling time at 3 min in the present work. The latent fingerprints detection that developed from Gd2MoB2O9:Eu3+ phosphors in this work exhibited clearly ridge characteristics under UV illumination. The results revealed thatGd2MoB2O9:Eu3+ phosphors are potential practical forensic science applications.

Sustainable Preparation of Nanoporous Carbons via Dry Ball Milling: Electrochemical Studies Using Nanocarbon Composite Electrodes and a Deep Eutectic Solvent as Electrolyte.

The urgent need to reduce the consumption of fossil fuels drives the demand for renewable energy and has been attracting the interest of the scientific community to develop materials with improved energy storage properties. We propose a sustainable route to produce nanoporous carbon materials with a high−surface area from commercial graphite using a dry ball−milling procedure through a systematic study of the effects of dry ball−milling conditions on the properties of the modified carbons. The microstructure and morphology of the dry ball−milled graphite/carbon composites are characterized by BET (Brunauer–Emmett–Teller) analysis, SEM (scanning electron microscopy), ATR−FTIR (attenuated total reflectance–Fourier transform infrared spectroscopy) and Raman spectroscopy. As both the electrode and electrolyte play a significant role in any electrochemical energy storage device, the gravimetric capacitance was measured for ball−milled material/glassy carbon (GC) composite electrodes in contact with a deep eutectic solvent (DES) containing choline chloride and ethylene glycol as hydrogen bond donor (HBD) in a 1:2 molar ratio. Electrochemical stability was tracked by measuring charge/discharge curves. Carbons with different specific surface areas were tested and the relationship between the calculated capacitance and the surface treatment method was established. A five−fold increase in gravimetric capacitance, 25.27 F·g−1 (G40) against 5.45 F·g−1, was found for commercial graphene in contact with DES. Optimal milling time to achieve a higher surface area was also established.