Milling Time Research Articles

Experimental and theoretical study of size-dependent phase evolution in NaCl-KCl alloys

In the present investigation, the formation of nanocrystalline bi-alkali halide (NaCl+KCl) obtained by combined low temperature (cryomilling) with room temperature (RT) milling was reported. The cryomilling, which is endowed with special ability to accelerated fracture and form free ionic salt crystals, is utilized for rapid refinement. This is followed by RT milling to form biphasic nanocrystallites. The bi-phase formation with the time of milling was characterized using a scanning electron microscope (SEM) and transmission electron microscope (TEM). The change in lattice parameter and introduction of micro-strain in the lattice (due to cold work and bi-phase formation) have been characterized using X-ray diffraction and deduce using theoretical calculations. The investigation reveals the influence of milling time on the shape and size of the crystallites along with formation of biphasic NaCl-KCl crystallites with inner core being NaCl surrounded by KCl crystals. The KCl powder particles get deposited on the surface of NaCl crystals to maintain the charge neutrality during ball milling. The shape of NaCl undergoes change from cuboid to cuboctahedron with the progression of milling time due to plastic deformation induced roughing. The temperature-dependent mechanical behaviour and associated mechanism of the milled NaCl-KCl system were discussed and supported by the thermodynamic modal. It is evident, NaCl-KCl is phase separating system, which accentuated at nanosized and hence, the formation of biphasic crystalline structure is observed during combined cryo and RT milling.

Effect of mechanical milling time on powder characteristic, microstructure, and mechanical properties of AA2024/B4C/GNPs hybrid nanocomposites

In this study, hybrid nanocomposites consisting of an AA2024 matrix reinforced with 1 wt% B4C nanoparticles and 1 wt% GNPs were produced using a powder metallurgy method assisted by mechanical milling. This study aimed to systematically investigate the effect of grinding time on powder characteristics (particle size, microhardness, and morphology) as well as microstructure, densification, and mechanical performance to optimize processing conditions for superior material properties. Microstructural characterization of powders and bulk samples were carried out using a SEM device equipped with EDS. The results indicate that with increasing milling time, the particle size significantly decreased, while the particle hardness increased substantially. Additionally, the sample milled for 8 h achieved the highest relative density among the hybrid nanocomposites, reaching a value of 95.3 %. Mechanical tests revealed that after 8 h of milling, the hardness and tensile strength reached peak values of 164 HB and 314 MPa, corresponding to increases of 56 % in hardness and 43 % in tensile strength compared to the unreinforced alloy. The analysis results confirm that the optimal properties were obtained after 8 h under all conditions.

Two-ways regulation of the emulsion gel properties of curdlan by dry ball milling treatment and their relationships with the microstructures, emulsification characteristics and gel properties of ball milled curdlan

Ball milling treatment could affect the microstructures, improve the emulsification properties of curdlan (CL) and regulate the emulsion gel properties of CL based emulsion gel in two-ways. With increasing ball milling time (1 h–8 h), the particle size first decreased and then increased, the relative crystallinity decreased, and the contact angle increased. Ball milled curdlan (BMCL)-6 h showed the best emulsifying property and stability, which was the combined effects of decreased particle size and increased hydrophobic property. Ball milling 1 h and 2 h significantly improved the hardness and chewiness of CL-based emulsion gels, while, ball milling 4 h–8 h could make the emulsion gels much softer and ice cream-like. When the emulsion gels were heated twice consecutively, the visual appearance and texture properties did not change significantly, indicating the excellent thermal stability of these emulsion gels. The BMCL based emulsion gel with adjustable gel properties and good thermal stability has a wide range of uses in the food system.

Machine Learning Modeling of the Mechanical Properties of Al2024-B4C Composites

Aluminum-based composites are in high demand in industrial fields due to their light weight, high electrical conductivity, and corrosion resistance. Due to its unique advantages for composite fabrication, powder metallurgy is a crucial player in meeting this demand. However, the size and weight fraction of the reinforcement significantly influence the components' quality and performance. Understanding the correlation of these variables is crucial for building high-quality components. This study, therefore, investigated the correlations among various parameters—namely, milling time, reinforcement ratio, and size—that affect the composite’s physical and mechanical properties. An artificial neural network model was developed and showed the ability to correlate the processing parameters with the density, hardness, and tensile strength of Al2024-B4C composites. The predicted index of relative importance suggests that the milling time has the most substantial effect on fabricated components. This practical insight can be directly applied in the fabrication of high-quality Al2024-B4C composites.

Investigation of Microhardness, Microstructural, Tribological, and Thermal Properties of Al7075/TiO2/Kaoline Hybrid Metal Matrix Composites Produced by Powder Metallurgy Process

The shift from traditional, single‐component metals and alloys continues, and researchers are currently investigating alternative materials. This evolution has led to the creation of innovative materials, including hybrid metal‐matrix composites. The present study aims to investigate the microstructural, surface morphological, and thermal properties of a novel Al7075/TiO2/Kaoline hybrid metal‐matrix composite prepared using high‐energy ball milling and sintering methods. In this study, phases related to the composite components are formed depending on the milling time, no undesirable phase is formed, but the peak intensities decreas as the milling time increases. Particle size increases from 63 to 215 μm with increasing milling time. Increasing the kaoline reinforcement ratio and sintering temperature increases the microhardness from 62.27 ± 2 to 75.83 ± 2 HV, and reduces the friction coefficient from 0.82 ± 0.01 to 0.62 ± 0.01. The wear rate of the composite without kaoline addition is 2.1 (mm3 m−1) × 10−3, while with 6 wt% kaoline addition, it decreases to 1.5 (mm3 m−1) × 10−3. There are no cracks in the composite other than plastic deformation due to sintering and wear. Peaks indicating endothermic and exothermic reactions during continuous heating occurr in the 635–750 °C temperature range.

Investigation of the Effect of Milling Time on Elemental Powders of Oxi‐Reduction Nickel and Hydrogenation–Dehydrogenation Titanium

Mechanical alloying (MA) is widely applied in the synthesis of blended elemental or prealloyed powders. This work evaluates the effect of milling time on elemental nickel and titanium powders produced by oxi‐reduction and the hydrogenation–dehydrogenation process, respectively. The powders are characterized by scanning electron microscopy, X‐ray diffraction, particle size, powder yield, and differential scanning calorimetry. It is observed that increasing the milling time promotes the formation of a structure composed of thin lamellae of nickel and titanium, which results in the beneficial effect of lowering the temperature for the formation of the intermetallic of the Ni–Ti system and in the powder yield achieved. The reduction of milling time in the MA process of NiTi alloys enhances technological efficiency by decreasing their overall processing time.

Dual‐Modal Sensing Skin Adaptive to Daylight, Darkness, and Ultraviolet Light for Simultaneous Full‐Field Deformation Measurement and Mechanoluminescence Responses

AbstractMechanoluminescence (ML) and digital image correlation (DIC) have emerged as promising optical methods to visualize and measure deformation fields. In this study, a dual‐modal sensing skin, called the ML‐DIC skin is introduced, that is capable of emitting ML and facilitating DIC measurements under various lighting conditions, including daylight, night or darkness, and UV irradiation. Four ML‐DIC skins are fabricated with or without carbon nanotubes (CNTs) using a composite powder consisting of SrAl2O4: Eu,Dy (SAO), and acrylic resin, with CNT milling times of 48, 72, and 96 h for three of four skins, respectively. DIC measurements are performed under multiple lighting conditions for measuring photoluminescence, persistence luminescence, and reflection. Uniaxial tension tests demonstrate the superior performance of ML‐DIC skins with CNTs compared with pristine SAO skins, with the skin subjected to 48 h of CNT dispersion exhibiting optimal performance. Further investigations focus on ML emission and DIC measurements near the crack‐tip vicinity of static and propagating cracks as well as on surfaces above subsurface cracks. The integration of ML and DIC techniques offers a versatile approach for comprehensive deformation analysis applicable to diverse environments, with implications for materials science, engineering, and structural health monitoring.

Impact of morphology of hydrophilic and hydrophobic bentonites on improving the pour point in the recycling of waste cooking oils

Waste Cooking Oils (WCOs) are generated worldwide through industrial food processing and household use, posing environmental concerns upon disposal. Bentonites often showed to be effective in removing minor contaminants in vegetable oil refining. The present research focused on the processing of raw WCOs using four bentonites, two commercials and two obtained by ball milling of the latest. The different bentonites (hydrophobic and hydrophilic) were characterized before and after ball milling (BM) procedure, including an exhaustive analyses of crystal structure, morphology and surface area via x-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and N2-physisorption technique. Optimization of BM processing in terms of milling time was achieved within 60 min. The milled powders were then tested as adsorbents for recycling WCOs with different degrees of decomposition (expressed in terms of free fatty acids, FFAs, content). Employing a design of experiments approach, the impact of five parameters (FFAs content, temperature, specific surface area, stirring, BM time) on the resulting pour point (PP), taken as a quality benchmark for recycled oil, was assessed. Quantitative multivariate statistical analysis revealed temperature's negligible role and identified the significant impact of two characteristics of the bentonite (specific superficial area and ball milling time), as well as the relevant role of the stirring during the treatment. At the end, hydrophilic bentonite resulted able to improve the PP of waste oils with a low content of free fatty acids of about 10 °C.

Effects of Degree of Milling on Nutritional and Edible Quality of High-Resistant Starch Rice

The aim of this study was to investigate the effects of milling degree on nutrient content, especially resistant starch (RS), and edible quality of starch rice variety Youtangdao3 (YTD3) with high RS. High RS rice variety YTD3 was processed with different milling times (0, 10, 20, 30, and 40s) to evaluate the effects on nutritional components, mineral content, vitamins, pasting properties, and cooking/eating quality. With the increase in milling time, the average milling reduction rate increased from 0 to 8.54, 11.81, 13.27, and 16%, which correlated with a decrease in the yield of head rice, crude fat, crude protein, and ash content. Minerals and vitamins, especially vitamin E and B vitamins, decreased significantly with increasing milling time. Sensory analysis revealed a decrease in rice hardness and an increase in viscosity with longer milling, suggesting improved palatability. However, excessive milling reduced the nutritional value of the rice. The study highlights the need for an optimal balance between the degree of milling (DOM) and the preservation of nutritional value to improve the overall quality of rice products. The results are important for guiding rice processing practices to maintain the health benefits of RS while preserving the sensory appeal of rice.

Waste to Wealth: One-Step Exfoliating of Spent Graphite to Build a Low-Cost Cathode for Lithium-Sulfur Batteries.

With the booming development of Li-ion batteries (LIBs), the recycling and reusing of spent graphite (SG) from LIBs is becoming increasingly crucial. Meanwhile, developing low-cost and efficient carbon hosts for lithium-sulfur (Li-S) batteries has gained widespread attention in the past decade. Nevertheless, the processing of carbon materials as sulfur hosts is often energy-consuming and complex. Herein, a simple and environmental-friendly strategy is proposed to reuse the SG to prepare graphene/sulfur composite cathode for Li-S batteries. Due to expanded layer spacing and defects of SG, sulfur molecules can strip it into a graphene-type host via ball milling. By optimizing the S/SG ratio and ball milling time, the as-prepared graphene/sulfur composite cathode with 70 wt.% sulfur content exhibits a high capacity of 1000 mAh g-1. With a high sulfur loading of 4.68 mg cm-2, the graphene/sulfur cathode can maintain 526 mAh g-1 after 400 cycles. This work provides a novel waste-to-wealth perspective for recycling spent graphite from LIBs to reuse in Li-S batteries.

Interface misfit of conventionally milled and novel hybrid full-arch implant-supported titanium frameworks

ObjectiveA hybrid manufacturing technique that combines selective laser melting (SLM) and computer numerical control (CNC) has been developed for the fabrication of implant-platform/framework interfaces (PFIs) for mandibular and maxillary full-arch implant-supported titanium frameworks. The aim of this study was to compare the discrepancies in specimens fabricated using the hybrid technique (termed SLM/m hereafter) with those in specimens fabricated by conventional CNC milling.Materials and methodsBased on a mandibular four-PFI CAD model and a maxillary six-PFI CAD model, four groups of titanium frameworks (eight per group, totaling 32) were fabricated according to the fabrication technique (SLM/m or milling) and number of PFIs (four or six). The frameworks were scanned by a structured light scanner and aligned with the CAD model in Geomagic Control X. Discrepancy was defined as the difference between the PFIs of the scanned framework and those of the CAD model. Discrepancies were measured and evaluated by multilevel analysis using a mixed-effects model (α = 0.05), followed by independent samples t-tests (α = 0.0125). Furthermore, the manufacturing times and raw-material costs were recorded and compared.ResultsThe maximum discrepancy values for the four-PFI and six-PFI hybrid frameworks were 52.2 and 64.3 μm, respectively. Multilevel analysis revealed that the fabrication technique and the number of PFIs had no significant effect on the discrepancy value. However, a significant interaction between the two factors was observed (P = 0.020). The discrepancies for the four-PFI hybrid frameworks were significantly lower than those for the four-PFI milled frameworks (P = 0.001). No significant difference in discrepancies between the six-PFI hybrid frameworks and six-PFI milled frameworks was observed (P = 0.697). Furthermore, the hybrid frameworks required only 11% of the raw materials and 25% of the milling time required for the conventionally milled frameworks.ConclusionSLM/m hybrid frameworks are viable, accurate alternatives to CNC-milled frameworks, with the added benefit of substantial cost reduction.

Mechanical processing of wet stored fly ash for use as a cement component in concrete

Wet storage effects on fly ash mean that processing may be necessary to achieve the physical properties required for use in concrete. This paper considers drying, de-agglomeration and milling of various wet stored fly ashes at laboratory and pilot/benchtop scales, towards meeting these. In the laboratory, different batch quantities and milling times with as-received/pre-screened materials were examined using a ball mill. Greater particle size reductions were obtained with increased milling time but at gradually reducing rates. Pre-screening and batch quantity had relatively minor effects on particle size reductions, with small differences also found between wet and dry stored fly ash. Extended milling time resulted in a darkening of colour; slight increases in loss-on-ignition, the main oxides content and crystalline components; reductions in water requirement (to a point); and greater reactivity. Similar effects were generally noted in concrete for the superplasticising admixture dose to achieve a target slump and compressive (cube) strength. At pilot/benchtop scale, a dryer-pulveriser and spiral jet mill were used, which gave general agreement with the behaviour noted in the laboratory, but with the effects tending to be less. Fineness levels in Standards were achievable, with subsequent performance in concrete, appearing to depend on the milling process used.

Response surface methodology and process optimization of spark plasma sintered parameters of Ti20Al20Cr5Nb5Ni19Cu12Co19 high entropy alloy

Study was carried out on the effect of milling and sintering process parameters on the relative density and microhardness property of a septenary non-equiatomic Ti20Al20Cr5Nb5Ni19Cu12Co19 high entropy alloy fabricated via spark plasma sintering (SPS) process at 100 °C/min constant heating rate, 5 min dwell time, and at a pressure of 50 MPa. A predictive model was developed through response surface methodology (RSM) using the SPS sintering temperature (ST) and milling time (MT) as the process variables. In order to reduce the number of experimental runs, the design of experiment (DOE) technique was used, to eventually avoid the trial-and-error process associated with conventional experimental procedures. The user-defined design (UDD) of the RSM was used to forecast the optimal operating parameters, and the outcome was validated by experiments. Findings indicate that MT and ST are important in achieving high densification, which leads to high densification and mechanical properties. Optimization model shows that, at MT of 7.20115 h and ST of 899.742 °C, desirable responses of 99.9 % relative density, percentage porosity of 0.0999994 % and a micro-hardness value of 835.21 HV can be attained.

Effect of processing parameters and carbon to metal ratio on microstructure and mechanical properties of (MoTaTiVW)Cx high entropy carbide produced by reactive spark plasma sintering

(MoTaTiVW)Cx high entropy ceramics with varying carbon to metal ratio in the range of 0.75-0.97 were synthesized by by reactive spark plasma sintering. The effect of ball milling time on particle size, phase evolution and carbon pick-up due to toluene decomposition were studied. Formation of single-phase high entropy carbide having face-centered cubic (FCC) crystal structure was confirmed by X-ray diffraction (XRD), electron backscattered diffraction (EBSD) and Selected area diffraction pattern (SAED) analysis of the sintered compacts. Transmission Kikuchi Diffraction images revealed presence of equiaxed nature of the grains. Transmission electron microscopy images revealed the presence of an intergranular phase at grain boundaries and triple junctions. 3D-Atom Probe Tomography studies showed uniform distribution of elements within the grains with some segregation of impurity elements Fe and Co to the grain boundaries indicating minor contribution of liquid phase sintering to densification. The grain size of single-phase sintered compacts ranged between 1.69 ± 0.60 μm to 4.6 ± 1.0 μm. A low sintering temperature and higher milling time resulted in finer grain size The microhardness was found to increase with milling time and C/M ratio. The microhardness, Young’s modulus and indentation fracture toughness lied between 2221 HV0.1 to 2732 HV0.1, 370 GPa to 473 GPa, 3.6 MPa.m1/2 to 4.4 MPa.m1/2, respectively. The highest microhardness and indentation fracture toughness was found to be 2732 ± 80 HV0.1 and 4.4 MPa.m1/2 on par with reported literature for other high entropy carbides.

The influence of ball milling conditions on the powder characteristics and sintering densification of Mo[sbnd]Cu alloy

Mechanical alloying was utilized to produce Mo-30Cu(wt%) composite powder. The effects of milling conditions on the powder characteristics and sintering densification were investigated. The morphological evolution during the mechanical alloying process can be categorized into four stages: 1-individual Mo and Cu particles, 2-coexistence of Mo particles and blocky MoCu composite particles, 3-coarse irregular composite particles, and 4-refined near-spherical composite particles or lamellar MoCu composite particles, depending on whether process control agent (PCA) is added. The mechanical alloying degree of the MoCu composite powder was deepened gradually from stage 1 to 4, which is influenced by the ball milling parameters. As the milling speed and milling time increase, the lattice strain and the alloying degree of the MoCu composite powders increase while the grain size of molybdenum particles decreases, which is conducive to accelerating the sintering density. Among these ball milling parameters, an elevated milling speed notably accelerates the mechanical alloying process and the sintering density. Under the milling speed of 600 r/min, ball to powder ratio (BPR) of 10:1, and milling time of 4 h, the grain size, lattice strain, and average particle diameter of the composite powder were measured to be 48.4 nm, 0.247 %, and 21.04 μm, respectively, with the particle morphology being nearly spherical. The sintered density of the MoCu composite reached 98.1 %, larger than the other composites.

Experimental validation of the amplitude ratio as a metric for milling stability identification

This paper presents the experimental validation of the amplitude ratio, a metric for milling stability identification. The amplitude ratio quantifies the severity of chatter by comparing the amplitude of the expected frequency content of a milling signal (i.e., tooth passing frequency, runout frequency, and harmonics) to the amplitude of the chatter frequency, if present. Through multiple iterations of a milling time domain simulation, the amplitude ratio diagram, which characterizes stable and unstable milling behavior over a range of spindle speeds and axial depths of cut, may be generated. In this paper, a comparison of the simulated and measured amplitude ratios for a series of milling test cuts is presented. It is shown that the amplitude ratio is suitable for identifying milling stability in both simulations and experiments. Additionally, it is shown that through judicious selection of low-cost sensors, implementation of the amplitude ratio is cost efficient. Direct comparison of the simulated and measured amplitude ratios demonstrates the effectiveness of the approach.

Zero-valent iron on graphite-cellulose biochar catalysts for the Fenton degradation of tetracycline from water

Tetracycline (TC), an antibiotic widely used in the treatment of animal and human diseases and promotion of animal growth. However, its uncontrolled discharge to water sources can also cause the promotion of antibiotic resistant bacteria and genes. In this study, graphite and cellulose were used as raw materials to construct a graphite-biochar (G-BC) by carbothermal reactions. This graphite-biochar was subsequently mixed with ZVI with various mass ratios by ball milling to produce graphite-biochars supported ZVI (ZVI/G-BC) catalysts, further used in the heterogeneous Fenton degradation of tetracycline. The materials were fully characterized by different techniques. The removal of TC by BC, G-BC and ZVI/G-BC was tested under different reaction conditions. The best synthesis conditions were achieved at a heating temperature of 700 °C, a graphite content of 20 %, a ball milling speed of 500 rpm, a ball milling time of 5 h, as well as a G-BC and ZVI mass ratio of 1:3. Graphite improves the conductivity and micropore area of the material, which enhances the removal of TC by ZVI/G-BC catalysts in Fenton-like reactions. TC was first oxidized to intermediate products and then further mineralized to CO2 and H2O. The best TC removal performance was obtained with a catalyst dosage of 1.1 g·L1, a hydrogen peroxide concentration of 140 mM and an initial pH value of 3. The reaction data fitted properly a pseudo first-order kinetic equation. TC removal as high as 91 % was achieved even in the 3rd round of reuse. This study reports a novel ZVI material with high conductivity and good TC removal performance.

Microstructure and magnetic properties of surfactant-assisted ball milling NdFe8Co2Mo2 powders and their nitrides

The NdFe8Co2Mo2 alloy ribbons were prepared by melt-spinning. The powder was prepared through surfactant-assisted ball milling, followed by nitriding to produce the NdFe8Co2Mo2Nx alloy. The alloy ribbons grain size decreases as the copper roller speed increases. At the speed of 30 m/s, a pure 1:12 phase alloy ribbons were produced. The grain size decreases with increasing the ball milling time, but the composition phases almost unchanged of the alloy powder. The grain size refine after nitriding, but the grain volume expands when the nitriding temperature exceeds 500 °C. With increasing ball milling time and nitriding temperature, the remanence (Mr) and coercivity (Hc) of the alloy powder increase first and then decrease. The alloy powder obtained from ball milling for 3 h after nitriding at 475 ℃ for 3 h, resulting in Mr was 44.43 Am2/kg, Hc was 0.434 T, and saturation magnetization (Ms) was 74.89 Am2/kg.

Experimental and simulation studies to optimize the mechanical alloying process of ODS-FeCrAl alloy powder

Oxide dispersion strengthened (ODS) FeCrAl alloy exhibits superior mechanical qualities at high temperatures and resistance to neutron irradiation, making it a highly promising material for accident-tolerant fuel cladding. The preparation of ODS-FeCrAl alloy powder by mechanical alloying can mix Y2O3 and FeCrAl alloy powder uniformly and promote the uniform dispersion of nanoscale oxide particles in the alloy matrix. The preparation of ODS-FeCrAl alloy powder by the mechanical alloying method is greatly influenced by the rotational speed. Therefore, this study uses a combination of experiments and numerical simulation to investigate the effects of different rotational speeds on the microscopic morphology, particle size and force of alloy powder during the ball milling process. The mechanically alloyed powder was subjected to XRD inspection to determine the optimum ball milling time at each rotational speed by means of the maximum lattice distortion, and then the powder micromorphology and particle size were analyzed. Then the forces on the powder and grinding ball during the ball milling process were analyzed by numerical simulation, and it was found that the collision force and normal force played a dominant role in the ball milling process. The combined experimental and simulation results determined that the ODS-FeCrAl alloy powder obtained by ball milling at 300 rpm for 35 h had the largest lattice distortion, fine grain size and uniform particle size, which achieved the best mechanical alloying effect.

Tuning optical properties of sustainable inorganic bismuth-based perovskite materials with organic ligands

We report a facile and environmentally friendly ball milling method for synthesizing Cs3Bi2Cl9 nanocrystals at different ball milling times: 30 min (BM1), 120 min (BM2), and 240 min (BM3). Structural analysis confirmed the formation of crystalline nanostructures. Optical studies revealed a tunable bandgap influenced by particle size, with a blue shift observed for smaller nanocrystals. Importantly, Cs3Bi2Cl9 demonstrated potential for optoelectronic applications as indicated by its interaction with 2,3-diaminonaphthalene and reduced charge carrier lifetime. These findings contribute to the growing interest in lead-free perovskites as sustainable alternatives for light-harvesting and conversion technologies. Increasing ball milling time from 120 to 240 minutes improved thermal stability between 200 °C and 610 °C. BM1 perovskite crystals showed significantly lower thermal stability, suggesting that the synthesis process influences crystal structure and thermal properties. However, thermogravimetric analysis (TGA) showed that BM2 and BM3 perovskite crystals exhibited exceptional thermal stability, withstanding temperatures up to 438.6 °C and 439 °C, respectively, without significant weight loss. This superior stability expands potential applications to high-temperature environments like concentrated solar power systems.