Ball-milled Powders Research Articles

Effect of Ball-Milled Steatite Powder on the Latent Heat Energy Storage Properties and Heat Charging-Discharging Periods of Paraffin Wax as Phase Change Material.

Phase change materials (PCMs) serve as an advantage in thermal energy storage systems utilizing the available sensible and latent heat. The PCMs absorb the thermal energy during the charging process and release it into the environment during the discharging process. Steatite is low cost and eco-friendly, with a thermal stability up to 1000 °C, and it is abundantly available in nature. This study investigates the steatite–paraffin wax-based PCM and the effect on the cyclic loads using a horizontal triplex-tube latent heat energy storage system. The thermal conductivity value of the milled steatite-based PCM composite was 7.7% higher than pure PCM. The PCM with the ball-milled steatite-fabricated composite exhibited better discharging characteristics, increasing the discharge time by 50% more than that of the pure paraffin wax. Moreover, the milled steatite-based PCM outperformed that incorporated with non-milled steatite with paraffin.

Fe-Ag pseudo-alloys obtained by wire electric explosion, ball milling and spark plasma sintering

• Fe-Ag pseudo-alloys formed by wire electric explosion and spark plasma sintering. • WEE powder was ball-milled to improve its structural uniformity. • In pseudo-alloy formed from milled powder, silver grains were 300-500 nm in size. • Material sintered from ball-milled powder showed a higher microhardness. • Porous silver with a uniform structure was obtained from sintered material. Structural features of Fe-25 wt.% Ag pseudo-alloys obtained by spark plasma sintering of the product of wire electric explosion (WEE) and the product of WEE processed by ball milling were comparatively investigated for the first time. In the sintered pseudo-alloy produced from the WEE powder, inclusions of iron 5-10 μm were found in the Fe-Ag composite matrix. The size of silver grains was of the order of 1 μm and 300-500 nm in the sintered materials produced from the WEE powder and ball-milled powder, respectively. The pseudo-alloys sintered from the ball-milled powder showed a higher microhardness than the material sintered from the WEE powder. Porous silver obtained from the pseudo-alloy sintered from the WEE powder by selectively dissolving iron showed micrometer-sized pores in the former places of iron particles of those sizes. In contrast, porous silver obtained from the pseudo-alloy sintered from the ball-milled powder had a uniform structure free from large pores.

Effect of particle size on the physicochemical and antioxidant properties of Forsythia suspensa (Thunb.)Vahl leaf powders

Four powders of Forsythia suspensa leaf were prepared by coarse grinding and subsequent ball milling. The effects of particle size on the physicochemical and antioxidant properties of the powders were evaluated. The results showed that the particle size of the powder decreased from 107.99 to 29.20 μm by ball milling for 5 h. In addition, the ball-milled powders had substantial advantages in water holding, solubility and swelling capacities. Thus, the ball-milled powders had a better dissolution of phenolic, flavonoid, and polysaccharide components (25.45, 1.99 and 44.19 mg/g of powder for 5 h of ball milling), ultimately resulting in a superior antioxidant activity (maximum reductions of 14.96% and 19.20% for DPPH and ABTS radicals, respectively). The FTIR analysis showed that the structure of the active ingredients remained intact after ball milling. In conclusion, ball milling is a promising technique for preparing Forsythia suspensa leaf powder with improved physicochemical and biological properties. • Forsythia suspensa powders were obtained by coarse grinding and ball milling. • The properties and activities of the powder are correlated with the milling time. • The hydration properties of ball-milled powders rise with decreasing particle size. • Decline of the flow and thermal properties after ball milling treatment was found. • Antioxidant activity enhanced with higher active ingredients of ball-milled powders.

Synthesis of single-phase (ZrTiTaNbMo)C high-entropy carbide powders via magnesiothermic reduction process

Preparation of high-entropy carbides in bulk quantities and in powder form via simple methods at relatively low temperature is challenging. Here, we report the first synthesis of (ZrTiTaNbMo)C high-entropy carbide (HEC) powders via magnesiothermic reduction process. In this, a mixture of individual metallic oxides, graphite and magnesium is treated at a temperature of 1350 °C under Ar atmosphere. The (ZrTiTaNbMo)C powders are obtained after acid leaching, deionized water cleaning and drying process, and synthesized powders shows single-phase face-centered cubic (fcc) structure with the oxygen content of only 0.35 wt% and particle-size range of 5–60 µm. Such powders are in potential demand for additive manufacturing techniques, while high dense HEC bulk ceramic is fabricated by hot pressing sintering using ball-milled HEC powders in preliminary researches. The successful synthesis of (ZrTiTaNbMo)C powders may guide the way towards synthesis of many other high-entropy carbide powders via magnesiothermic reduction process.

Properties of Cold Sprayed Coatings Produced from Boron-Based Ball-milled Powder Mixture

Properties of Cold Sprayed Coatings Produced from Boron-Based Ball-milled Powder Mixture

The effect of process parameters on the physical and mechanical properties of Ti fabricated by selective laser melting using ball milled powders

In this study, influences of the processing parameters on the physical and mechanical properties of Ti parts fabricated by selective laser melting (SLM) using ball milled powders were investigated systematically. Single-tracks experiment indicated that when significant depth (dint) of the molten pool overlap area was greater than 68.49 μm and a high-quality morphology of the molten pool was formed, fully dense SLM-ed samples can be obtained. The tensile strength and elongation of SLM-ed samples fabricated at different process parameters were in the range of 940–985 MPa and 9.5–17.3%, respectively. When the laser beam power, scan speed and hatch spacing were 175 W, 600 mm/s, and 0.09 mm, respectively, the samples exhibited the highest mechanical properties with a tensile strength of 985.4 MPa and an elongation of 17.3%, which exceeded the ASTM B265-15 Ti-6Al-4V alloy level. The outcomes of this work have facilitated in developing titanium parts using low-cost modified HDH-Ti powder, and have also opened many dimensions for future investigations.

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.

Mechanical Activation-Assisted Solid-State Aluminothermic Reduction of CuO Powders for In-Situ Copper Matrix Composite Fabrication

In this study, combustion synthesis involving mechanical milling and subsequent sintering process was utilised to fabricate Cu/AlxCuy/Al2O3 in-situ composite through the aluminothermic reduction of CuO powders. First, CuO and Al powders were mixed, and ball milled for 30–150 min to facilitate self-propagating high-temperature synthesis (SHS). Then, mechanically activated Al-CuO powders were mixed with elemental Cu powders and experienced subsequent cold compaction and sintering processes. The reactions during synthesis were studied utilising differential thermal analysis (DTA), X-ray diffraction (XRD), and scanning electron microscopy (SEM). Densification and hardness of green and sintered bodies were also obtained. The results indicated that despite the negative free energy of the aluminothermic reaction, an initial activation energy supply is required, and mixed Al-CuO powders did not show significant progress in the combustion synthesis method. The aluminothermic reaction became probable whenever the activation energy was entirely provided by high-energy ball milling or by the sintering of ball-milled Al-CuO mixed powders. DTA results showed that the aluminothermic reaction temperature of Al-CuO decreased with milling times, whereas after 150 min of ball milling, the reaction was completed. XRD patterns revealed that the formation of Al2Cu and Al2O3 reinforcing phases resulted from CuO reduction with Al. Al4Cu9, Cu solid solution, and Al oxide phases were observed in sintered samples. The relative density of the samples was reduced compared to the green compacted parts due to the nature of the Cu-Al alloy and the occurrence of the swelling phenomenon. The hardness results indicated that in-situ formation of reinforcing phases in samples that experienced thermally assisted thermite reaction yielded superior hardness.

Effect of microstructural parameters of ball-milled Si powder on reactivity with water to produce H2: Way forward for on-demand H2 production

Silicon (Si) nanoparticles prepared by ball-milling technique can show many exciting properties including improved reactivity with water to produce hydrogen (H2) compared to that of the bulk. This is attributed to the change in microstructural parameters such as particle size and dislocation density of nano-crystalline Si during the milling process. The understanding of such effects is of great importance for the technological applications of these Si nanoparticles in H2 generation from water for fuel cells, and our present work deals with this crucial aspect. In our present investigation, we found that ball-milling technique can be used to tailor the microstructural parameters of milled Si sample where milling time can greatly influence the particle size and dislocation density. In water-splitting experiment, we noticed that these microstructural parameters as well as state of agglomeration of milled Si samples in water have profound effect on the reactivity of Si with water to evolve H2. Furthermore, selecting the right alkali can speed up such H2 release, making rapid on-demand production of H2 viable, particularly for fuel cell applications.

Correlation between milling-induced strain, microstructure, and magnetic properties in anisotropic SrFe12O19 powders

Strontium hexaferrite (SrFe12O19) powders synthesized via conventional solid-state route are mechanically milled using air jet-mill and ball-mill techniques to produce anisotropic SrFe12O19 powders. Jet-milled and dry ball-milled powders showed higher strain (0.13%) compared to wet ball-milled powders (0.05%). On annealing, jet-milled powder exhibited better recovery of strain compared to the ball-milled powders. Enhancement in coercivity after annealing is maximum in jet-milled samples (1.7 kOe to 5.2 kOe). Angle-dependent magnetic hysteresis measurements suggest a difference in the nature of strain induced in jet-mill and ball-mill methods. Maximum remanence (0.81) is observed in both jet-milled and dry ball-milled powders, however, jet-milled powders showed a better retention of remanence (0.74) after annealing than the ball-milled powders (0.64). A stark contrast in the microstructure of jet-milled and ball-milled powders is revealed from SEM images. Particle size distribution curves confirm a considerable re-agglomeration in the ball-milled samples. The role of milling-induced strain and microstructure in obtaining anisotropic SrFe12O19 powders with optimum remanence and coercivity is discussed.

Facile and Low-Cost Fabrication of Cu/Zn/Sn-Based Ternary and Quaternary Chalcogenides Thermoelectric Generators

In this work, Cu/Zn/Sn-based ternary and quaternary chalcogenides inks were synthesized via hot injection and/or from ball-milled powders. The synthesized inks were used to fabricate thermoelectric generators (TEGs) based on p-type chalcogenide and n-type aluminum-doped zinc oxide (AZO) thin films via spin-coating and magnetron sputtering, respectively. This work highlights the first-ever attempt in a facile and scalable method to fabricate thin-film TEGs using safe, low-cost, and abundant materials. Four different TEGs were fabricated using Cu2ZnSnS4 (CZTS), Cu2ZnSnSe4 (CZTSe), Cu2.125Zn0.875SnS3Se (CZTSSe), and Cu2SnS3 (CTS) chalcogenides. Thermoelectric transport analysis confirmed the respective p- and n-type natures of the chalcogenides and AZO, with their Seebeck coefficients compatible to be coupled in a p–n device. In addition, a full-device analysis has been carried out, and several factors affecting the performance of TEGs were investigated, including the composition, density, and presence of secondary phases in chalcogenide thin films. The maximum power per unit active planar area obtained for CZTS, CZTSe, CZTSSe, and CTS TEGs at a temperature difference (ΔT) of 160 K was ∼43, ∼188, ∼23, and ∼59 nW/cm2, respectively, making CZTSe/AZO TEG the champion device.

Waste to Hydrogen: Elaboration of Hydroreactive Materials from Magnesium-Aluminum Scrap

Ball-milled hydroreactive powders of Mg-Al scrap with 20 wt.% additive (Wood’s alloy, KCl, and their mixture) and with no additives were manufactured. Their hydrogen yields and reaction rates in a 3.5 wt.% NaCl aqueous solution at 15–35 °C were compared. In the beginning of the reaction, samples with KCl (20 wt.%) and Wood’s alloy (10 wt.%) with KCl (10 wt.%) provided the highest and second-highest reaction rates, respectively. However, their hydrogen yields after 4 h were correspondingly the lowest and second-lowest percentages—(45.6 ± 4.4)% and (56.0 ± 1.2)% at 35 °C. At the same temperature, samples with 20 wt.% Wood’s alloy and with no additives demonstrated the highest hydrogen yields of (73.5 ± 10.0)% and (70.6 ± 2.5)%, correspondingly, while their respective maximum reaction rates were the lowest and second-lowest. The variations in reaction kinetics for the powders can be explained by the difference in their particle sizes (apparently affecting specific surface area), the crystal lattice defects accumulated during ball milling, favoring pitting corrosion, the morphology of the solid reaction product covering the particles, and the contradicting effects from the potential formation of reaction-enhancing microgalvanic cells intended to induce anodic dissolution of Mg in conductive media and reaction-hindering crystal-grain-screening compounds of the alloy and metal scrap components.

Spark plasma sintering treatment of cold sprayed materials for synthesis and structural modification: A case study using TiC-Cu composites

Materials obtained by cold spraying (CS) are subjected to post-spray treatment to increase cohesion between the particles. In this work, spark plasma sintering (SPS) was used for reactive processing of cold spray deposits for the first time. A mixture of a Ti-C-3Cu ball-milled powder and copper was used as a feedstock material for the formation of Cu matrix composites by CS. SPS treatment of CS deposits was used for the in-situ synthesis of TiC, formation of a dense structure and elimination of microcracks at the interface between the substrate and the deposit. The mechanism of structural changes in the composite agglomerates upon reaction was discussed. The TiC-Cu composite particles in the microstructure of the SPS-treated material possess a microhardness of 390 ± 40 HV0.025, which makes them suitable as reinforcing elements of composite nature in the design of Cu matrix materials. This study shows that SPS treatment is a promising solution for post-spray processing of cold spray coatings.

The Effect of Slag on the Mechanical Properties of Coralline-Activated Materials and the Formation and Transformation of Mineral Crystals

In this study, coralline-activated materials were prepared using ball-milled coral powder as cementitious material and coral sand as fine aggregate. XRF (X-ray fluorescence) and chemical dissolution tests were carried out to determine the content and reactivity of various elements in coral powder. The compressive strength of the developed composites was evaluated at different ages, and the formation and transformation of mineral crystals in coralline-activated samples were further analyzed by XRD (X-ray diffractometer). The results show that the calcium content in coral powder was as high as 89.5% (loss on ignition). However, only 56% of the active calcium could participate in the polymerization reaction. The silicon and aluminum content was too low, and the slag addition could improve the deficiency of silicon and aluminum in coral powder. With the increase in slag content (from 0% to 50%), the compressive strength of the composites increases significantly. Nevertheless, the enhancement is not pronounced when the slag content exceeds 50%. The increase in slag amount can stimulate the transformation of calcium minerals, e.g., aragonite and calcite, into hydrated calcium silicate and calcium aluminosilicate gels, which significantly enhances the resulting compressive strength.

Manufacturing of Textured Bulk Fe-SmCo5 Magnets by Severe Plastic Deformation.

Exchange-coupling between soft- and hard-magnetic phases plays an important role in the engineering of novel magnetic materials. To achieve exchange coupling, a two-phase microstructure is necessary. This interface effect is further enhanced if both phase dimensions are reduced to the nanometer scale. At the same time, it is challenging to obtain large sample dimensions. In this study, powder blends and ball-milled powder blends of Fe-SmCo5 are consolidated and are deformed by high-pressure torsion (HPT), as this technique allows us to produce bulk magnetic materials of reasonable sizes. Additionally, the effect of severe deformation by ball-milling and severe plastic deformation by HPT on exchange coupling in Fe-SmCo5 composites is investigated. Due to the applied shear deformation, it is possible to obtain a texture in both phases, resulting in an anisotropic magnetic behavior and an improved magnetic performance.

FeCoNiCu Alloys Obtained by Detonation Spraying and Spark Plasma Sintering of High-Energy Ball-Milled Powders

FeCoNiCu Alloys Obtained by Detonation Spraying and Spark Plasma Sintering of High-Energy Ball-Milled Powders

Mechanochemically synthesized Al–Fe (oxide) composite with superior reductive performance: Solid-state kinetic processes during ball milling

Recently, mechanical ball milling (BM), a simple and green powder processing method, has been successfully applied to improve the performance of zero-valent metals (ZVMs) for efficient water treatment. However, until now BM is still regarded as a “black box” in which the processes of the solid-state reaction during activation remain unclear. In this paper, firstly, FeSO4·7H2O crystal was used to activate and modify inert microscale zero-valent aluminum (mZVAl) by BM to synthesize Al–Fe (oxide)bm composite that showed superior reactivity in reductive removal of various contaminants and excellent reusability, which may be mainly ascribed to the newly formed iron oxide layer on mZVAl by mechanochemical reaction. At the same time, the formation of iron oxides on mZVAl was closely related to BM parameters. Further kinematic analysis revealed that the occurrence of mechanochemical reaction depended on the impact energy and input energy, which BM speed and BM time were two main factors determining reaction extent on the premise that the precursors were full dose. Moreover, kinetic fitting uncovered the solid-state reaction mechanism between mZVAl and FeSO4·7H2O conformed to three-dimensional diffusion and phase boundary reaction models. This study ponders deeply upon the mechanochemical process and solid reaction mechanism during the preparation of Al–Fe (oxide)bm composite, which deepens comprehensions of material synthesis procedures by BM and promotes applications of ZVM-based composite in polluted water or wastewater treatment.

Ball-milling treatment of gas-atomized Ti 48Al 2Cr 2Nb powder and its effect on preventing smoking during electron beam powder bed fusion building process

Smoking is the explosive powder-scattering by Coulomb interaction, and it is a difficult issue to avoid in electron beam powder bed fusion (EB-PBF) process. In this study, we investigated the effectiveness of mechanical ball milling to prevent powder-bed smoking in EB-PBF using gas-atomized Ti 48Al 2Cr 2Nb powder. The surface of the gas-atomized powder was confirmed to be composed of outer porous TiO 2 + Al 2 O 3 and inner dense Al 2 O 3 rich bilayer oxide film that gives rise to a high electrical resistance. The electrical resistivity after ball milling with 300 rpm (BM300) was significantly decreased due to the formation of the degenerated TiO 2 and Ti n O 2n–1 -type suboxide. The electrical equivalent circuit of the powder bed of BM300 was essentially a single resistor-capacitor (RC) circuit, owing to the mechanically deformed outer oxide film. Besides, through ball milling at 300 rpm for 30 min, the relaxation time of the gas-atomized powder was significantly decreased 1/16 times, and its electrostatic force decreased approximately 1/57 times. Finally, the suppressing effect of smoking on the EB-PBF building process was experimentally examined using ball-milled powders. It was clearly demonstrated that mechanical ball milling is an effective method to restrict smoking during the EB-PBF building process without any chemical treatment and composition change.

Effect of V addition on tribocorrosion wear behavior of boride layer produced on AISI 1040

In this study, the effect of the addition of vanadium (V) on the densification, microstructure, and wear behavior of borosintered powder metallurgy steels was investigated. Ball-milled powders containing 0, 1, 5 and 10 wt.% V were cold-compacted under 200 MPa pressure and then subjected to borosintering at 1100°C for 2 h in ambient air. The characterization of the boride layers formed after borosintering was conducted by scanning electron microscopy, X-ray diffraction, microhardness tests, nanoindentation, surface roughness measurements, and ball-on-disk-type wear tests. Wear testing was carried out under 10 N load for a total sliding distance of 250 m in ambient air and in a 3.5% sodium chloride (NaCl) solution. While the thickness of the boride layer decreased with increasing V content, its hardness and modulus of elasticity also increased, owing to the formation of additional vanadium boride (VB) and vanadium carbide (V2C) phases. Wear resistance increased with increasing V content, and the samples tested in 3.5% NaCl displayed lower coefficients of friction and higher wear resistance compared to the samples tested in ambient air. Reduced wear in 3.5% NaCl was attributed to the cooling and lubricant effects provided by the 3.5% NaCl solution.

Microstructural Transitions during Powder Metallurgical Processing of Solute Stabilized Nanostructured Tungsten Alloys

Exploiting grain boundary engineering in the design of alloys for extreme environments provides a promising pathway for enhancing performance relative to coarse-grained counterparts. Due to its attractive properties as a plasma facing material for fusion devices, tungsten presents an opportunity to exploit this approach in addressing the significant materials challenges imposed by the fusion environment. Here, we employ a ternary alloy design approach for stabilizing W against recrystallization and grain growth while simultaneously enhancing its manufacturability through powder metallurgical processing. Mechanical alloying and grain refinement in W-10 at.% Ti-(10,20) at.% Cr alloys are accomplished through high-energy ball milling with transitions in the microstructure mapped as a function of milling time. We demonstrate the multi-modal nature of the resulting nanocrystalline grain structure and its stability up to 1300 °C with the coarser grain size population correlated to transitions in crystallographic texture that result from the preferred slip systems in BCC W. Field-assisted sintering is employed to consolidate the alloy powders into bulk samples, which, due to the deliberately designed compositional features, are shown to retain ultrafine grain structures despite the presence of minor carbides formed during sintering due to carbon impurities in the ball-milled powders.