High-speed Ball Milling Research Articles

Comparative study on the hydrogen storage performance of as-milled MgRENi rapid quenched alloy catalyzed by metal sulfides

The composites of Mg20Pr1Sm3Y1Ni10 as-quenched alloy and 3 wt.% M (M = CoS, CoS2, MoS2) catalyst were prepared by high-speed vibration ball mill. The effects of metal sulfides on the hydrogenation and dehydrogenation dynamics of alloys were compared. The results show that the as-milled composites contain a large number of amorphous embedded by a small amount of nanocrystals, and there are many point defects. After ball milling, the crystal grain size in the composites containing CoS is relatively larger, followed by CoS2 and MoS2 again. After hydrogenation, the amorphous phase is crystallized to form Mg2NiH4, YH3, Pr8H18.96, Sm3H7, Mg, Co or Mo phases, however, Mg2Ni, YH2, PrH2 and Ni3Y phases appeared after dehydrogenation. The maximum hydrogenation capacity of the composites containing CoS, CoS2 and MoS2 are 3.939, 4.265 and 4.507 wt.%, respectively. The hydrogenation saturation ratio of composite containing MoS2 is higher than that of the composites containing CoS and CoS2. The dehydrogenation activation energy of the composites containing CoS, CoS2 and MoS2 is 107.76, 68.43 and 63.28 kJ.mol−1.H2. On the improvement of hydrogen storage performance of Mg20Pr1Sm3Y1Ni10 alloy, the catalytic effect of MoS2 sulfide is better than that of CoS2 sulfide, and which is better than CoS sulfide.

Electronic Impacts on the Solvent-Free Mechanochemical Synthesis of Salophen Ligands in Ball Mill

To realize the scope of the solid-solid reaction, the functional solid diamines reacted with solid 3-ethoxysalicylaldehyde under high-speed ball milling in a solvent-free environment. The findings showed that a wide range of Salophen ligands could be produced in good to excellent yields. In comparison to the similar Salophen synthesis to date, the current study provided solvent-free, fast reaction, high yield, and easy work-up.

Fatigue behavior and tribological properties of laser additive manufactured aluminum alloy/boron nitride nanosheet nanocomposites

Laser additive manufacturing is a promising approach to prepare near-neat shape parts from Al nanocomposites with high mechanical and tribological properties. Owing to its lubricious nature, boron nitride nanosheets (BNNSs) were added into AlSi10Mg alloy via high-speed ball milling and laser metal deposition (LMD) to manufacture self-lubricating Al alloy nanocomposites with outstanding wear resistance and fatigue performance. The study shows that number of cycles-to-failure due to tensile fatigue increased from 103 for pure AlSi10Mg to 106 upon adding only 0.1 wt% of BNNSs. At 0.2 wt% BNNSs, the friction coefficient and wear-out volume of AlSi10Mg alloy decrease by 58% and 57%, respectively. Scanning electron microscopy micrographs show that pure AlSi10Mg has a worn surface of grooves, wide ridges, debris and large protrusions of worn material along the groove edges. The wear mechanism is mainly plastic deformation, delamination and adhesion in pure AlSi10Mg. On the other hand, the LMD-built AlSi10Mg/BNNS composites exhibit less rough surface with clear wear trails due to the thin lubricant layer formed from the extruded BNNSs during the test. An extended finite element model for the crack propagation during fatigue testing is developed, where the obtained results are in accord with the experimental measurements. The present study shows that additive manufacturing technology is capable to fabricate Al matrix composites with tailored properties for various design applications.

Soft magnetic composites FeSiAl/MoS2 with high magnetic permeability and low magnetic loss

Choosing Two-Dimensional (2-D) layered semiconductor material MoS2 as the insulator, FeSiAl/MoS2 composites were synthesized by mixing MoS2 and aerosolized FeSiAl in a certain mass ratio. The structure, morphology and magnetic properties of FeSiAl/MoS2 composites were measured by XRD, SEM, XPS, VSM and B-H analyzer. The SEM results show that high-speed ball milling breaks the binding of weak Van der Waals force between MoS2 layers, and nano-thick MoS2 micron flakes wrapped on the FeSiAl spherical surface. The results of magnetic properties show that not only the FeSiAl/MoS2 composite achieves a higher magnetic permeability due to the thin MoS2 flakes clinging to the FeSiAl particle surface, but also the eddy current between the metallic particles is blocked, resulting in a great reduction of eddy current loss. The permeability results show that the relaxation frequency of FeSiAl/MoS2 composites exceeds 1 MHz, which is suitable for application at high frequency. The magnetic loss of FeSiAl/1 wt%MoS2 composite reaches 454kWm−3 under the condition of f= 0.1 MHz and B= 0.1 T, which is about three quarters of that of FeSiAl soft magnetic composites for commercial application.

“Effect of tungsten carbide (WC) on electrochemical corrosion behavior, hardness, and microstructure of CrFeCoNi high entropy alloy”

High-entropy alloy HEA (CrFeCoNi) was reinforced with variety of weight percentages of 5:20 wt.% WC particles. The alloy samples were mechanically prepared in a ball roll mill for 25 h by 10:1 ball to powder ratio at 180 rpm. Then WC was mixed with the prepared alloys in a high-speed ball mill for 1 h by 350 rpm under a controlled atmosphere. The mixed samples were compacted by a uniaxial press under 700 MPa and then sintered at 1200 °C for 90 min under air atmosphere. The corrosion behavior of the tested samples in 3.5 wt.% NaCl solution was investigated using electrochemical polarization measurements. The microstructure of the sintered samples with high relative density showed three phases, which were FCC matrix, W-rich carbide, and Cr-rich carbide and homogeneously distributed all over the alloy matrix. The hardness of the (CrFeCoNi)1-X (WC)X HEAs was increased gradually with the increasing of WC content from about 336.41 HV up to 632.48 HV at room temperature. The results indicated that the addition of WC improves the corrosion resistance. Especially, the 20 wt.% of WC addition remarkably enhanced the comprehensive corrosion resistance and easy passivation of (CrFeCoNi)1-X(WC)X HEAs. Also, the wear rate of 0 wt.% WC HEA is (1.70E-04) which is approximately 4.5 times higher than the wear rate of 20 wt.% WC HEA (3.81E-05); this means that wear resistance is significantly improved with the increase of WC content.

The dehydrative etherification of benzyl alcohols via mechanochemical reaction

A facile, solvent-free, lower-cost, and efficient high-speed ball milling reaction catalyzed by Cu(NO3)2·3H2O/P2O5 is developed for the synthesis of symmetric ethers from dehydration of benzyl alcohols by taking a benzylic carbocation as intermediate.

Preparation and properties of lead-free FeS/Cu-Bi composites by flake powder metallurgy via shift-speed ball milling

Lead-free FeS/Cu-Bi (FCB) self-lubricating composites were prepared via shift-speed ball milling (SSBM) and powder metallurgy. The microstructure and evolution of mixed powders were studied, and the mechanical and tribological properties of the FCB composites were tested. SSBM includes long-term low-speed ball milling (LSBM) and short-term high-speed ball milling (HSBM). In the early LSBM, the matrix phase CuSn10 powder was flattened into flakes, and the lubricating phases FeS and Bi were refined and gradually dispersed on the CuSn10 flakes. After short-term HSBM, FeS and Bi were further trapped on the CuSn10 flakes, which not only improved the bonding performance between the lubricating phase and copper alloy but also protected the continuity of the copper alloy matrix from additional damage. 6 + 1 h SSBM (6 h LSBM + 1 h HSBM) improved the mechanical properties, antifriction and wear resistance of FCB composites. Compared with traditional HSBM, SSBM provides a new way to prepare FCB self-lubricating composites with better comprehensive properties.

Preparation of ultramicroporous volume carbon using high-speed ball-milling and its selective adsorption of CH4 in low-concentration coalbed methane

Preparation of ultramicroporous volume carbon using high-speed ball-milling and its selective adsorption of CH4 in low-concentration coalbed methane

Tailoring mechanical and in vitro biological properties of calcium‒silicate based bioceramic through iron doping in developing future material

Dense iron-doped akermanite ceramics with 0.3, 0.6 and 0.9 mol% of Fe3+ were synthesized via high-speed planetary ball milling and subsequently subjected to sintering at 1200 and 1250 °C. The aim of the current work was to investigate the effect of trivalent iron (Fe3+) in tuning the physicomechanical and in vitro biological properties of akermanite. The incorporation of Fe3+ into akermanite host and sintering at a high temperature of 1200 °C resulted in a synergistic effect in enhancing the sinterability and densification of akermanite ceramics. Although varying the Fe3+ content, it was found that similar densification and mechanical properties (i.e., diametral tensile strength, Vickers microhardness and fracture toughness) were observed for the doped ceramics at 1250 °C, indicating that this newly developed formulation is temperature-dependent. Fe3+-doped akermanite ceramics revealed greater in vitro bioactivity as compared to undoped akermanite, demonstrated by better coverage of needle-like apatite precipitates after 21 days of immersion in simulated body fluid. Additionally, Rat-1 cells cultured in direct contact with Fe3+-doped akermanite ceramics showed almost double levels of cell proliferation than their undoped counterpart on both 3 and 7 days of culture. Our finding suggests that 0.9Fe-AK ceramic is a suitable formulation to be considered for future bone substitute material as it provides sufficient mechanical strength as well as good bioactivity and the ability to encourage cell proliferation.

Tailoring Cu nano Bi self-lubricating alloy material by shift-speed ball milling flake powder metallurgy

A novel method for preparing lead-free Cu nano Bi (CNB) alloy materials by nano Bi powder and shift-speed ball milling (SSBM) flake powder metallurgy was proposed. To improve the mechanical and tribological properties of the alloy materials, the spherical CuSn10 powder was firstly extruded and sheared into flakes by low-speed ball milling (LSBM) in the SSBM system. Meanwhile, the nano Bi powder was evenly dispersed and coated on the CuSn10 flakes. The mechanical alloying between mixed powders and the cold welding of flake CuSn10 flakes containing nano Bi into layered particles were then realized through short-time high-speed ball milling (HSBM) in the SSBM system. While promoting the uniform dispersion of lubricating phase Bi, the surface area of matrix CuSn10 flake was increased so as to achieve better combination of CuSn10 matrix in the material. Results show that the mechanical properties of the CNB material prepared through nano Bi powder and SSBM flake powder metallurgy improved compared with the Cu-Bi material prepared by HSBM. In addition, the antifriction and wear resistance improved by 30% and 80%, respectively.

A novel economically viable method of preparation of graphene-rubber masterbatch for its application in tyre compound

Properties of rubber composites can be improved by the incorporation of graphene. However, it is practically not feasible to use graphene in tyre compound because of its high-cost and difficult to disperse it in the rubber matrix. The present study demonstrates the development of a novel, cost-effective method of manufacturing graphene-rubber masterbatch (GRMB). Aqueous dispersion of graphene (10 wt%) was prepared by high-speed ball milling (500 RPM for 7 h) of graphite in presence of surfactant (5% w/w with respect to graphite). The graphene thus produced was characterized through X-ray diffraction (XRD), Raman spectroscopy, and atomic force microscopy (AFM). The XRD results confirmed the exfoliation of graphitic layers, defect generation in graphene was identified from Raman spectroscopy and AFM image proved the formation of graphene sheets. The graphene dispersion thus produced was mixed with natural rubber (NR) latex using magnetic stirrer at 500 RPM for 3 h maintaining 15% of graphene in GRMB. After mixing, the mass was dried in a vacuum oven at 80 °C. After that 3.33 phr (parts per hundred parts of rubber by weight) of GRMB (0.5 phr graphene) was added in truck and bus radial (TBR) tyre tread compound. The addition of GRMB significantly improved tensile modulus (21.5%), tensile strength (3.8%), hardness (5.1%) and tear strength (17.4%) of the regular TBR tyre tread compound. In GRMB, graphene was in pre-dispersed form enabling easy dispersion in final tyre compound. The graphene thus produced was economically viable since no expensive materials, and complicated synthesis and purification methods were used.

Mechanochemical ring-opening metathesis polymerization: development, scope, and mechano-exclusive polymer synthesis.

Ruthenium-alkylidene initiated ring-opening metathesis polymerization has been realized under solid-state conditions by employing a mechanochemical ball milling method. This method promotes greenness and broadens the scope to include mechano-exclusive products. The carbene- and pyridine-based Grubbs 3rd-generation complex outperformed other catalysts and maintained similar mechanistic features of solution-phase reactions. High-speed ball milling provides sufficient mixing and energy to the solid reaction mixture, which is composed of an initiator and monomers, to minimize or eliminate the use of solvents. Therefore, the solubility and miscibility of monomers and Ru-initiators are not limiting factors in solid-state ball milling. A wide variety of solid monomers, including ionomers, fluorous monomers, and macromonomers, were successfully polymerized under ball milling conditions. Importantly, direct copolymerization of immiscible (ionic/hydrophobic) monomers exemplifies the synthesis of mechano-exclusive polymers that are difficult to make using traditional solution procedures. Finally, the addition of a small amount of a liquid additive (i.e., liquid-assisted grinding) minimized chain-degradation, enabling high-molecular-weight polymer synthesis.

A mechanochemical domino reaction: From α-methylbenzyl alcohols to diacylfuroxans

A domino reaction was discovered in which diacylfuroxans were prepared directly from α-methylbenzyl alcohols in a solvent-free reaction through the intermediates of the corresponding acetophenones by combining the reagents of Fe(NO3)3·9H2O and P2O5 under high-speed ball milling reaction condition.

α‐Amino Acids and α,β‐Dipeptides Intercalated into Hydrotalcite: Efficient Catalysts in the Asymmetric Michael Addition Reaction of Aldehydes to N‐Substituted Maleimides

AbstractIn this work, a series of α‐amino acids (L‐Phe, D‐Phe, L‐Trp) and several α,β‐dipeptides (H2N‐L‐Val‐N‐Bn‐β‐Ala‐COOH and H2N‐L‐Leu‐N‐Bn‐β‐Ala‐COOH) intercalated into hydrotalcite (Mg/Al, x=0.333) were prepared by high speed ball milling (HSBM) assisted rehydration/reconstruction methods, followed by sonication and mechanical stirring. All organic‐inorganic hybrid samples were characterized by powder X‐ray diffraction (XRD) and FTIR‐ATR spectroscopy. The catalytic activity of the resulting hydrotalcite‐supported materials (natural and hybrid) was evaluated in the asymmetric Michael addition reaction of α,α‐disubstituted‐aldehydes to N‐substituted‐maleimides. Pristine (HTS), calcined (HTC) and water‐reconstructed (HTR‐l) hydrotalcite‐derived materials exhibited very low catalytic activities, affording racemic mixtures of the anticipated Michael adduct. By contrast, hybrid materials showed better activities, especially HTR‐α‐amino acid catalysts afforded Michael products in up to 94 % yield and with rather high enantioselectivity (enantiomeric ratio (e.r.) up to 99 : 1) at room temperature under neat reaction conditions. The effect of solvents and Brønsted basic or acidic additives was evaluated using the best hybrid catalyst, HTR‐L‐Phe. In addition, recycling and reuse of the catalyst (up to 4 cycles) and large‐scale experiments was successfully carried out.

Mechanochemical sulfonation of aromatic compounds using NaHSO4·H2O/P2O5

A series of aromatic sulfonic acids is synthesized by subjecting arenes and NaHSO4·H2O to high-speed ball milling in the presence of P2O5. It is suggested the aromatic sulfonation occurs via in situ generated H2SO4 to give aromatic sulfonic acids. In some cases, formation of diaryl sulfones was observed.

Mechanochemical Regulation of Unstable Acyl Azide: Ir(III)-Catalyzed Nitrene Transfer C–H Amidation under Solvent-Free Ball Milling Conditions

In this study, we investigate the mechanochemical activation of acyl azide for direct C–H amidation with excellent C–N bond selectivity, fast rate, enhanced reactivity, solvent-free condition, and broad scope. Thermally unstable acyl azide, prone to Curtius rearrangement, was found to be controllable under mechanochemical ball milling conditions. Investigation of the mechanochemical process window of acyl azide led us to define highly selective Cp*Ir(III)-catalyzed acyl azide activation to acyl nitrene species and direct C–H amidation protocol. In addition to the expected merits of mechanochemistry, the newly developed high-speed ball milling method allows for carbamoyl azide utilization, which showed a limited scope under thermal solution conditions, registering to a list of mechanochemically preferred reactions.

Structural and magnetic properties of hard-soft BaFe12O19/(Zn0.5Co0.5)Fe2O4 ferrites

Hard-soft nanocomposites of (1 − x) BaFe12O19/x(Zn0.5Co0.5)Fe2O4, for x = 0.00, 0.25, 0.50, 0.75 and 1.00, were prepared via co-precipitation and high-speed ball milling techniques, respectively. The synthesized samples were characterized via x-ray diffraction, transmission electron microscope, Fourier transform infrared (FTIR), and vibrating sample magnetometer. XRD revealed the formation of hard-soft nanocomposites. TEM indicated that the two phases are well distributed and the particle size distribution is narrower for low content of soft phase, leading to better exchange coupling between the grains. Magnetic measurements were performed at 300 K and 77 K. The results showed a good single-phase magnetic behavior, verifying the good exchange coupling between hard and soft phases. For low (Zn0.5Co0.5)Fe2O4 content, the dipolar interactions were dominated by the exchange-coupling interactions. Additionally, the optimum values of saturation and remanent magnetizations, coercivity, and squareness ratio were obtained for x = 0.5. This was attributed to the dominance of exchange-coupling interaction. The enhancement of magnetic properties and energy product (BH)max for nanocomposites at low temperature is skilled in the reduction of the thermal fluxes of magnetic moments at the surface. The maximum energy product (BH)max was observed in C2 at both temperatures with a smaller value than that of pure BaFe12O19.

Fabrication and characterization of a novel environment-friendly inorganic fireproof adhesiveused for fire resistant doorsets

A novel environment-friendly inorganic fireproof adhesive was prepared with sodium silicate, fumed silica, light calcium carbonate, aluminum hydroxide and magnesium hydroxide by high-speed mixing and ball milling. The bond strength, formaldehyde and VOC emissions, thermal properties and fire performance of such adhesive were investigated. The bond strength of the adhesive was increased with the adding of the fumed silica, which reached 1.8 MPa when the amount of fumed silica was 1.5 wt.%. Formaldehyde and VOC emissions of this adhesive were far lower than those of the requirements in Chinese standards. The combustion grade of this adhesive could achieve A1 and its smoke toxicity grade could achieve AQ1, which was the safest grade of flammability for building materials.

Exchange spring behaviour in BaFe12O19/CoFe2O4 magnetic nanocomposites

Abstract In this work, nanopowders of BaFe12O19 and CoFe2O4 and nanocomposites of (1−x) BaFe12O19/xCoFe2O4, for x = 0.00, 0.25, 0.50, 0.75 and 1.00, were prepared via co-precipitation and high-speed ball milling techniques, respectively. For structural analysis, the X-ray diffraction revealed the formation of hexagonal BaFe12O19 and spinel CoFe2O4 ferrites, and the average crystallite sizes were about 35 nm and 15 nm, respectively. The transmission electron microscope indicated that the two phases are well distributed and the grain sizes of the composite powders are verified employing the size distribution histograms where two peaks were obtained separately for both ferrites. From EDX spectra, it was shown that all samples exhibit an excellent compositional homogeneity verifying the presence of both phases in the obtained nanocomposite powders. Magnetic measurements were performed via a vibrating sample magnetometer at 300 K and 77 K. The results showed a good single-phase magnetic behavior, proving the good exchange coupling between hard and soft phases. For low CoFe2O4 content, the dipolar interactions were dominated by the exchange-coupling interactions. Additionally, the optimum values of saturation and remanent magnetizations as well as the squareness ratio were obtained for the x = 0.5. This was attributed to the dominance of exchange-coupling interaction. Magnetic properties for nanocomposites were improved as the temperature falls from room temperature down to 77 K. This increase is skilled to the reduction in the thermal fluxes of magnetic moments at the surface.

Mechanically induced solvent-free esterification method at room temperature.

Herein, we describe two novel strategies for the synthesis of esters, as achieved under high-speed ball-milling (HSBM) conditions at room temperature. In the presence of I2 and KH2PO2, the reactions afford the desired esterification derivatives in 45% to 91% yields within 20 min of grinding. Meanwhile, using KI and P(OEt)3, esterification products can be obtained in 24% to 85% yields after 60 min of grinding. In addition, the I2/KH2PO2 protocol was successfully extended to the late-stage diversification of natural products showing the robustness of this useful approach. Further application of this method in the synthesis of inositol nicotinate was also discussed.