Effect Of Ball Milling Process Research Articles

Effect of Ball-Milling Process on Microwave Absorption Behaviors of Flaky Carbonyl Iron Powders.

Electromagnetic (EM) wave absorption performance is greatly affected by the microscopic morphology of the absorbing material particles. In this study, a facile and efficient ball-milling method was applied to increase the aspect ratio of particles and prepare flaky carbonyl iron powders (F-CIPs), one of the most readily commercially available absorbing materials. The effect of ball-milling time and rotation speed on the absorption behaviors of the F-CIPs was investigated. The microstructures and compositions of the F-CIPs were determined using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The EM parameters were measured using a vector network analyzer (VNA) in the frequency range of 2-18 GHz. The results indicated that the ball-milled flaky CIPs exhibited a better absorption ability than the raw spherical CIPs. Among all the samples, the sample milled at 200 r/min for 12 h and the sample milled at 300 r/min for 8 h showed remarkable EM parameters. The ball-milling sample with 50 wt.% F-CIPs had a minimum reflection loss peak of -14.04 dB at a thickness of 2 mm and a maximum bandwidth (RL < -7 dB) of 8.43 GHz at a thickness of 2.5 mm, a result that conformed with the transmission line theory. Hence, the ball-milled flaky CIPs were considered to be beneficial for microwave absorption.

Effect of Ball-Milling Process on Microstructures and Mechanical Properties of Heterostructured 2024Al Alloy Prepared by Powder Thixoforming

Effect of Ball-Milling Process on Microstructures and Mechanical Properties of Heterostructured 2024Al Alloy Prepared by Powder Thixoforming

Preparation and wear resistance of dual-scale structure cemented carbide spherical teeth

Based on commercially available WC (particle sizes of 0.9 μm and 2.4 μm) and Co, a dual-scale structure WC-6Co cemented carbide was prepared via conventional roller ball milling and following vacuum sintering. Effect of ball milling process on the microstructure, densities and mechanical properties were investigated together with the toughening mechanism of the dual-scale structure. The results showed that the dual-scale structured cemented carbide has excellent comprehensive mechanical properties, and its transverse rupture strength, hardness and fracture toughness are 3077 MPa, 1570 HV30 and 10.6 MPa m1/2, respectively. The drilling spherical teeth was prepared by the optimized technology and subjected to impact wear test, the failure mechanism of cemented carbide spherical teeth in drilling operations is studied. The CM-2 spherical teeth had a more reasonable distribution structure of coarse and fine of WC, and exhibited more excellent impact wear resistance in the impact wear test of granite.

Effect of ball milling process on the mechanical and thermal properties of the nanodiamond/2024Al composites

In this study, 5 wt.% nanodiamond (ND) reinforced 2024Al matrix composites (ND/2024Al) were fabricated with various ball milling processes. The microstructure, compressive yield strength (σyc) and coefficient of thermal expansion (CTE) of ND/2024Al composites were investigated. It is found that the addition of 5 wt.% NDs significantly increases the σyc and decreases the CTE of 2024Al. High energy ball milling further increases σyc and decreases CTEs of ND/2024Al composite due to it enhances the fine grain strengthening of α-Al matrix and the dispersion strengthening of NDs, decreases the thermal mismatch stress at the ND/α-Al matrix interface, and increases the constraint of NDs on α-Al. The composites fabricated by the combinations of ball milling speeds and times of (5−7) h×(200−250)rpm and 9 h×300 rpm have the highest σyc and the lowest CTE respectively. Considering the different influence of ball milling parameters on σyc and CTEs, a evaluation coefficient α=σycC⋅εkcCσycM⋅εkcM⋅CTEMCTEC is proposed to evaluate the synergistic influence of mechanical properties and CTEs on the dimensional stability of ND/2024Al composites. Large value of α may lead to high dimensional stability of material, hence the α can be used to determine the ball milling parameters.The ball milling process of 250−300 rpm ball milling speeds and 5−7 h ball milling times are recommended based on α, which causes a 95–100 % increase in σyc and a 30–35 % decrease in CTE compared with 2024Al alloy, respectively.

Effect of ball-milling process in combination with the addition of carbide microparticles on the microstructure and wear resistance of a Co–Cr–W alloy prepared by powder metallurgy method

Co–Cr–W alloys were widely used in the inlet exhaust valve of aeroengine. However, the traditional manufacturing process of Co–Cr–W alloys can not meet the demand for higher comprehensive performance, and an optimum method needs to be developed. Herein, a Co–Cr–W alloy reinforced by exogenous carbides was prepared by the powder metallurgy method. Effect of ball-milling time on the microstructure and wear resistance of the alloy was investigated, and the formation mechanisms of the reinforcing phases were discussed. Results showed that with prolonging the ball-milling time, the uniformity of the reinforcing phases was improved, grain refinement was achieved, the hardness increased, a suitable bonding interface was formed between the matrix and reinforcing phases, and better wear resistance was thus achieved. However, when the ball-milling time increased from 60 h to 70 h, local segregation of the reinforcing phases occurred, the hardness decreased from 64 HRC to 60 HRC, and the friction coefficient increased from 0.53 to 0.58. Based on our experimental results, we proposed two formation mechanisms of the reinforcing phases (carbides): In-situ precipitation from the matrix and in situ autogenic reaction between the elements of the matrix and the added carbides (WC and Cr3C2 particles). Both mechanisms contributed to the formation of M23C6 and M6C carbides. Our results underscore the importance of added reinforcing phases and help to optimize the ball-milling process in preparing the Co–Cr–W alloys.

Influence of ball milling process on microstructure and properties of Ni-based coating by laser cladding

Ni50/(Ti, W)C composite coating was produced by laser cladding. The effect of ball milling process on the homogenization of coating microstructure and coating properties was studied. The microstructure, phase composition, microhardness, and wear resistance of the coating were investigated. The formation and growth of in situ synthesized ceramic particles were analyzed. The results showed that the coating presented a dense and homogeneous microstructure with few pores and no cracks. Ceramic particles (Ti, W)C were in situ synthesized in Ni-based coating. The fining of different kinds of powders can also lead to different microstructure of coatings. A large number of fine and irregular (Ti, W) C precipitated from the composite coating by laser cladding with ball milled Ti + W powder. When the composite powders were milled, the coating was not only reinforced phase, but also the matrix phase γ-(Fe, Ni) content increased. After laser cladding, the composite powders which only ball milling Ti + W powders, the microhardness and wear resistance of the composite coating were improved.

Effect of ball milling process on the photocatalytic performance of CdS/TiO2composite

AbstractCdS/TiO2composite photocatalysts were made by the method of secondary ball milling at different ball milling speeds, milling time, and material ratios. After the secondary ball milling process, parts of the samples were calcined at high temperatures. X-ray diffraction (XRD) and UV-Vis diffuse reflectance spectroscopy (DRS) were used to observe the powder particle size, structural defect, bandgap, and absorption spectrum of the samples. Combined with the observation results, the effects of ball milling speed, time, material ratio, and high-temperature calcination on the photocatalytic performance of CdS/TiO2composite samples were analyzed. Furthermore, the methyl orange (MO) was chosen to simulate pollutants, and the photocatalytic degradation rate of CdS/TiO2composite photocatalysts for MO was evaluated under sunlight and UV irradiation conditions. The photocatalytic degradation efficiency of CdS/TiO2photocatalyst under UV irradiation is much higher than that under sunlight irradiation. The experimental results reveal that secondary ball milling can effectively promote the formation of CdS/TiO2composite nanostructure and the high-temperature calcination can reduce the bandgap width, which makes the samples easier to be excited. When the ball milling speed, time, and material ratio were respectively 400 rpm, 10 h, 25:75, and then calcined at high temperature, after 2 h of irradiation under UV light, CdS/TiO2composite photocatalysts exhibited maximum photocatalytic degradation efficiency of 57.84%.

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

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

Fabrication and Analysis of Vanadium-Based Metal Powders for Selective Laser Melting

Vanadium Alloy is a type of advanced nuclear material with many ideal properties compared as traditional nuclear materials, which has very wide and important application in first-wall and blanket structural material for fusion power plant applications. So it has attracted increasing attentions, especially on new manufacturing methods, such as selective laser melting and so on. In this paper, the comparative study of the powders obtained by mechanical mixing method, dry grinding method and wet grinding method respectively was performed to evaluate the effect of ball milling process on the microstructure and degree of alloying of the vanadium-based powder mixtures with the nominal composition of V5Cr5Ti vanadium alloy. The powders prepared by dry grinding method exhibits better spherical-like morphology and degree of alloying than those prepared by mechanical mixing method and wet grinding method, which indicates that dry grinding method can be used to prepare the superfine vanadium alloy powders for selective laser melting. This work provides a new method as well as important insights into the preparation of superfine vanadium alloy powders for selective laser melting additive manufacturing technology.

Effect of ball milling process on coercivity of nanocrystalline SmCo5 magnets

In this paper, the effect of ball milling process on remanence and coercivity of nanocrystalline SmCo5 magnets was systematically investigated. Nanocrystalline SmCo5 magnets were prepared by high energy ball milling and spark plasma sintering. And their vast difference of remanence and coercivity were analyzed thoroughly. The anisotropic SmCo5 magnets prepared by wet-milling with surfactant (oleylamine, OY) have high remanence, but the coercivity is much lower than the isotropic magnets prepared by dry-milling. Further analysis indicates the milling process induced changes on the size and shape of grains are the key factors influencing the coercivity. The amorphous powders prepared by dry-milling were crystallized during sintering and the magnets have small and homogeneous grains, while the anisotropic nanoflakes prepared by wet-milling could be well oriented but the magnets have lower coercivity due to the larger and inhomogeneous grains.

Effect of ball milling process on the structure of local clay and its adsorption performance for Ni(II) removal

The effect of ball milling process on the properties of the natural local clay including structural changes and adsorption capacity for the removal of Ni(II) ions from aqueous solutions, was investigated. The local clay was ground at varying times from 5 to 20h with a 10:1 or 20:1 weight ratio of the balls to powder, which produced six different ball milled clays (BM-Clay1 to BM-Clay6). Ground clays were then characterized by particle size measurement, X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy analysis, and adsorption experiments. These analyses were performed to evaluate the changes in particle size distribution, morphology, crystallinity, and adsorption characteristics. According to XRD analysis, the degree of amorphization increased with grinding time, and the present crystalline phase in the final ball milled clay was found to be quartz, which was the associated phase in the original unmilled clay mineral. FTIR studies indicated the destruction of the layers of the montmorillonite upon milling. Adsorption experiments revealed that under similar conditions, BM-Clay2 has the most adsorption capacity for Ni(II) ions. Adsorption characteristics of this ball milled clay for the removal of Ni(II) ions from aqueous solutions was examined in batch adsorption studies under different conditions of contact time, solution pH, adsorbent dose, and initial Ni(II) concentration. The Langmuir maximum adsorption capacity was found to be 29.76mg/g at pH7 and 25°C. The adsorption kinetics data showed better agreement with the pseudo second-order kinetic model. Also, both surface adsorption and intra-particle diffusion contributed to the rate limiting steps in the adsorption of Ni(II) on clay adsorbent. In conclusion, grinding of local clay using ball milling process can significantly increase the adsorption capacity of the clay for Ni(II) removal from aqueous solutions.

A comparison of field-dependent rheological properties between spherical and plate-like carbonyl iron particles-based magneto-rheological fluids

This work proposes different sizes of the plate-like particles from conventional spherical carbonyl iron (CI) particles by adjusting milling time in the ball mill process. The ball mill process to make the plate-like particles is called a solid-state powder processing technique which involves repeated welding, fracturing and re-welding of powder particles in a high-energy ball mill. The effect of ball milling process on the magnetic behavior of CI particles is firstly investigated by vibrating sample magnetometer. It is found form this investigation that the plate-like particles have higher saturation magnetization (about 8%) than that of the spherical particles. Subsequently, for the investigation on the sedimentation behavior the cylindrical measurement technique is used. It is observed from this measurement that the plate-like particles show slower sedimentation rate compared to the spherical particles indicating higher stability of the MR fluid. The field-dependent rheological properties of MR fluids based on the plate-like particles are then investigated with respect to the milling time which is directly connected to the size of the plate-like particles. In addition, the field-dependent rheological properties such as the yield stress are evaluated and compared between the plate-like particles based MR fluids and the spherical particles based MR fluid. It is found that the yield shear stress of the plate-like particles based MR fluid is increased up to 270% compared to the spherical particles based MR fluid.

Effect of Ball Milling Process on the in Situ Synthesis of Nano-TiB Whiskers

Ball milling process has an important effect on the microstructure and the morphology of final powder products and the corresponding as-sintered samples. In the present study, Ti-7Al-0.2B (wt%) mixed powder was ball-milled by low-energy and high-energy types of ball mills, and then the milled powder was sintered by hot-pressing. On this basis, the morphology evolution of the powder was analyzed, and the microstructures of the reinforcements in the as-sintered composite were investigated. Research results show that in the low-energy ball milling process, mechanical alloying occurs between the powder particles. TiB whiskers formed in sintering process are long and thin without linked coarse crystals bars or clusters. Under the high-energy milling, the average particle size of the powder is refined remarkably to 1 μm, and Ti(Al) supersaturated solid solution or even amorphous structure is formed during the milling process. In the following sintering process, nano-scale TiB whiskers are synthesized and they are uniformly distributed in the matrix.

Carbon dioxide storage in olivine basalts: Effect of ball milling process

The goal of this study is to propose a cost-effective method for the optimization of the ex situ carbonation of basaltic rocks. The ball milling process was applied to a sample of olivine basalt from the Troodos ophiolite complex (Cyprus) for the first time, in order to fabricate novel nanomaterials for CO2 storage. The purpose was to accelerate the kinetics of rock–fluid reactions during the carbonation procedure. Various methodologies were used for the characterization of the starting rock material and the ball-milled samples. Preliminary results reveal that only a few hours of wet ball milling with ethanol as process control agent can induce significant changes to olivine basalt towards improvement of its performance for CO2 storage. Specifically, CO2 uptake measurements via the use of the temperature-programmed desorption (TPD) technique indicate that 4h of ball milling with 50wt.% ethanol can lead to an enhancement of the carbonation of olivine basalt by 295%. The experimental results strongly suggest that (i) olivine basalts have important CO2-storage capacity and are very promising lithotypes for ex situ carbonation, and (ii) the ball milling process provides hopes for its use at an industrial scale as a preparation technique for the safe and permanent ex situ storage of CO2.

The Effect of Ball Milling Process on Sintering and Densification Enhancement of W-Bronze Composites

Τhe miscibility of W in Sn and Cu is extremely poor. The wettability of W by those two elements is limited. To tackle this problem, two step ball milling process of the W–bronze elemental powders was proposed in this study. The softness of Sn in the first step was exploited to modify the surface morphology of the W particles. In the second step Cu was added to the ball milled mixture. To achieve this goal, two different sets of W50wt. %–pre mix bronze compacts of ball milled and of as received powders were utilized. Sintering process was performed at 1150°C. The two–step ball milled powders yielded sintered compacts of fine polygonal and homogeneous W network skeletal dispersed in bronze matrix. Sintered compacts of about 95% theoretical density were produced by this technique.

A novel low temperature synthesis technique of sol–gel derived nanocrystalline alumina abrasive

The effect of ball milling process, co-doped seed and two step sintering technique on the properties of sol–gel derived alumina abrasive sintered at low temperature was investigated. The results showed that ball milling time with 10 h can be effective in enhancing the activity of the precursor and the microstructural uniformity of sintered alumina abrasive. A small amount of Al2O3–(NH4)3AlF6 co-doped seed addition had potential synergistic effects for reducing α-Al2O3 phase transformation temperature and improving the mechanical property of alumina abrasive. A remarkable suppression of grain growth was achieved by controlling sintering temperature with two-step sintering method. Therefore, by using ball milling process, co-doping α-Al2O3–(NH4)3AlF6 seed and two-step sintering technique, the sol–gel derived uniform nanocrystalline alumina abrasive is easily achieved at low temperature. Nanocrystalline alumina abrasive prepared at these conditions exhibited excellent mechanical properties and wear resistance compared to fused corundum abrasive and those sol–gel derived corundum abrasive with conventional sintering methods.

Effect of ball milling process on the microstructure of titanium-nanohydroxyapatite composite powder

Abstract Titanium-nanohydroxyapatite (Ti-nHA) composite powders, composed of titanium with 10 vol.% and 20 vol.% of nano-hydroxyapatite, were milled in a planetary ball mill using alcohol media to avoid excessive heat. XRD and SEM were performed for characterization of the microstructure, and the homogeneity of Ti/HA nanocomposite powder was evaluated by EPMA with prolonged ball milling time. The results show that under the condition of wet milling, the grain size of Ti-nHA composite powders is decreased with the increase in ball milling time and the amount of the addition of nHA. While for milling of 30 h. the nanocomposite powder with fine structure, which consists of the nano-hydroxyapatite (nHA) particles and titanium (Ti) phase, is obtained. Three stages of milling can be observed from the element mapping of Ti, Ca. and P by EPMA; meanwhile, it is found that the nHA would be more homogenously distributed after milling for 30 h.

The effects of ball milling process on the diameter dependent fracture of single walled carbon nanotubes

The effect of ball milling process on the fracture of single walled carbon nanotubes (SWNT) is investigated using gel electrophoresis and Raman spectroscopy. A comparative Raman spectroscopy analysis, performed on the migrated nanotubes in the gel, shows that large diameter tubes are cut shorter and move faster in the gel. The D peak of Raman spectrum increases after an extended operation of the ball milling process, while that of the ultrasonicated nanotubes does not show an apparent change.