Ball Milling For Different Periods Research Articles

Preparation, characterization and the antimicrobial properties of metal ion-doped TiO2 nano-powders

TiO2 samples doped with lithium, sodium, magnesium, iron or cobalt were prepared by high-energy ball milling for different periods of time. The crystalline phase, chemical composition, crystalline size and photo-absorption were characterized by X-ray diffraction spectroscopy (XRD), X-ray photoelectron spectroscopy (XPS) and Ultraviolet visible diffuse reflectance spectroscopy (UV - Vis - DRS), Fourier transform infrared spectroscopy (FT - IR) and scanning electron microscopy (SEM). The antimicrobial properties of the modified TiO2 samples were evaluated with E. coli and S.aureus assays. The results of the XRD show that the TiOSO4, Ti3O5, Li2TiO3 and NaTi2O4 phases appear along with Li, Na and Mg doped TiO2. However, XPS spectra indicated that Ti exists as both Ti3+ and Ti4+ in Na-doped TiO2 samples. Ti3+, due to its narrow band gap, is highly active in promoting visible light-induced photocatalytic activity. SEM images showed that the crystalline size of TiO2 is reduced and has a common-round and hexagonal plate morphology after milling. The modified TiO2 samples had the best antimicrobial activities after 3h of milling. In particular, the antimicrobial rate of TiO2 5% doped with transition metals (Co, Fe) reached 100% against E. coli, but the antibacterial rate against S. aureus for Co and Fe dopants was 98.4% and 98.2%, respectively.

Influencing the crystallization of Fe80Nb10B10 metallic glass by ball milling

Melt-spun amorphous Fe80Nb10B10 ribbons were subjected to ball milling for different periods. The results show that ball milling not only induces the formation of nano-crystalline α-Fe during milling, but also drastically changes the crystallization behavior of the residual amorphous phase. In contrast to the as-spun ribbon, which crystallizes during heating through the formation of the metastable Nb5Fe33B10 phase and subsequent decomposition into stable α-Fe and a small fraction of Fe2B and NbFeB, ball milling progressively suppresses the formation of Nb5Fe33B10 as primary crystallization product and promotes the formation of α-Fe at low temperatures. The ball-milled nano-crystalline/amorphous powders have a saturation magnetization 2.5–3 times higher than the as-quenched amorphous ribbon along with Curie temperature increase by about 70 K with respect to the parent as-spun material. The structure and related magnetic properties of the milled material do not significantly change in the bulk samples synthesized by powder consolidation at temperatures up to ∼900 K, which indicates that the stable nature of α-Fe makes this nano-crystalline/amorphous composite material potentially suitable for a wide range of high temperature applications.

Evaluation of ball-milling time on the physicochemical and antioxidant properties of persimmon by-products powder

Abstract Persimmon by-products are known to contain higher bioactive constituents and biological activities than several other plant by-products. The present study investigated the effect of ball-milling time on the physico-chemical and antioxidant properties of persimmon seed, peel and calyx powders. The by-products were ball-milled using a planetary ball-mill for different periods of time. Increasing ball-milling time from 12 to 24 h improved the specific surface area, solubility, and DPPH radical scavenging activities of all by-products. The variable milling time also did not have any deleterious effect on bioactive constituents, reducing power and iron chelating abilities of seed powder. Ball-milling reduced the water holding capacity of all by-products but did not affect the oil holding capacity. Based on FTIR spectroscopy, increasing milling time did not alter the major constituents of all the by-products. Thus, longer ball-milling time (24 h) at relatively higher rpm (500 rpm) has the potential to produce superfine powders with improved physicochemical and antioxidant activities, thereby adding value to various applications including food. Industrial relevance Cost effectiveness and eco friendliness are major consideration in the processing of materials. Planetary ball-mill treatment offers an alternative processing method for the utilization of fruit and vegetable industrial wastes. Owing to the nature of some materials, understanding processing time can help in the prediction and regulation of physicochemical, technological and antioxidant properties of materials.

Magnetic Characterization of Nanocrystalline Co-B-Si-Fe-Mo Alloys

Fabrication of nanocrystalline Co-B-Si-Fe-Mo magnetic alloys by means of mechanical alloying was the goal of this study. In this regard, different powder mixtures containing Co70B30−x Si x (x = 10, 15, 20) and Co70B20Si5Fe5−x Mo x (x = 0, 2.5, 5) (at.%) were mechanically milled in a planetary ball mill for different periods of time. The produced samples were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), and vibrating sample magnetometer (VSM). The produced alloys exhibit magnetic properties with the saturation of magnetization and coercivity in the range of 30–260 Oe and 100–180 emu/g, respectively. The highest saturation of magnetization and the lowest coercivity appear in alloys with higher B content. Moreover, Fe element has a suitable effect and Mo element has a destructive effect on soft magnetic properties of Co70B20Si5Fe5−x Mo x alloys.

고에너지 볼 밀링이 Skutterudite계 CoSb<sub>3</sub>의 열전 및 전하 전송 특성에 미치는 영향

In this study, we investigate the effect of high-energy ball milling on thermoelectric transport properties in double-filled <TEX>$CoSb_3$</TEX> skutterudite (<TEX>$In_{0.2}Yb_{0.1}Co_4Sb_{12}$</TEX>). <TEX>$In_{0.2}Yb_{0.1}Co_4Sb_{12}$</TEX> powders are milled using high-energy ball milling for different periods of time (0, 5, 10, and 20 min), and the milled powders are consolidated into bulk samples by spark plasma sintering. Microstructure analysis shows that the high-energy ball milled bulk samples are composed of nano- and micro-grains. Because the filling fractions are reduced in the bulk samples due to the kinetic energy of the high-energy ball milling, the carrier concentration of the bulk samples decreases with the ball milling time. Furthermore, the mobility of the bulk samples also decreases with the ball milling time due to enhanced grain boundary scattering of electrons. Reduction of electrical conductivity by ball milling has a decisive effect on thermoelectric transport in the bulk samples, power factor decreases with the ball milling time.

High energy ball milling of titania and titania–ceria powder mixtures

Titania alone and several titania–ceria blends of powders were milled by high energy ball milling for different periods of time. Phases, crystal size, particle size and morphology were evaluated. The research has demonstrated that milling reduces the mean crystallite size to less than 30nm for any time whereas powder particles coalesce into coarse agglomerates. At the same time anatase titania transforms to rutile after 3hour milling, but a thermal treatment at 700°C for 1h partially recovers the original crystal structure. The behaviour of ceria–titania blends is similar to that of titania alone, but the reversibility of the anatase–rutile transformation does not occur when the quantity of ceria is greater than a critical level which we have set between the composition with Ce/Ce+Ti ratios of 5 and 10wt.%.

Effect of ball-milling time on the structural characteristics of biomedical porous Ti–Sn–Nb alloy

The structural characteristics of biomedical porous materials are crucial for bone tissue to grow into a porous structure and can also influence the fixation and remodeling between the implant and the human tissues. The current study has been investigating the effect of the ball-milling variable of time on the structural characteristics and pore morphology of a biomedical porous Ti–16Sn–4Nb (wt.%) alloy. The alloy was synthesized using high-energy ball milling for different periods of time, and the porous Ti–16Sn–4Nb alloy was fabricated by using a space holder sintering process. The resultant powder particles, bulk, and porous samples were characterized using a scanning electron microscope (SEM), laser particle-size analyzer, chemical analysis, X-ray diffraction analysis (XRD), and the Vickers hardness test. The results indicated that the inner pore surface, pore wall architecture, degree of porosity, pore size and the inter-pore connectivity of the sintered porous alloy are all considerably affected by ball-milling time.

Mechanically activated self-propagating high-temperature synthesis of La 0.9Sr 0.1Ga 0.8Mg 0.2O 3− δ as an electrolyte for SOFC

In this paper, we report on synthesis of highly pure La 0.9Sr 0.1Ga 0.8Mg 0.2O 3− δ (LSGM9182) powder with high crystallinity by mechanically activated (MA) self-propagating high-temperature synthesis (SHS), in which the synergy effects of MA and SHS on final and intermediate products were mainly examined. In the experiments, raw materials of La 2O 3, SrCO 3, Ga 2O 3, Mg and NaClO 4 were fractured and well mixed by planetary ball milling for different periods from 0 h to 24 h, then the bottom surface of the green compacts were electrically ignited for producing pure LSGM9182 through the propagation of sustainable exothermic reaction. The final and intermediate products, shortly after MA treatment, were characterized by XRD, SEM, XRF and particle size analyzer. During the planetary ball milling, the raw materials became gradually amorphous due to disordering of crystal structure. Interestingly, the longer milling operation caused the larger particle size of the raw material because nanoparticles, generated by the milling, became easily massed together. More significantly, the MA pretreatment improved a reactivity of the SHS to purify the product. In particular, the combination of MA–SHS with ball milling of 24 h at 300 rpm gave the highest-grade LSGM9182 product of nano-sized primary particles. The results appealed that the SHS after the MA treatment was quite effective for initiating, activating, sustaining and completing the solid–solid reaction synthesis of functional perovskite-type oxide with mild exothermic heat.

Effects of micronization on properties of Chaenomeles sinensis (Thouin) Koehne fruit powder

Abstract Chaenomeles sinensis (Thouin) Koehne fruits were traditionally used for food and medicinal materials. With the aim of providing necessary reference about the micro-powder as ingredients in food and medicine, this study investigated the physicochemical properties and antioxidation of three C. sinensis (Thouin) Koehne fruit micro-powders, prepared by pulverizing its coarse fruit powder with planetary ball mill for different periods of time. The results demonstrated that planetary ball mill could effectively pulverize coarse powder to different micro-sizes. As milling time increased, the median diameter was significantly decreased and particle size distribution width narrowed, the angle of repose and swelling capacity improved to a different extent, oil holding capacity of micro-powder was not affected, the water holding capacity, total flavonoid content, DPPH and NO2− radical-scavenging capacity and reducing power were decreased. The results suggested that micronize processing could improve some properties of C. sinensis (Thouin) Koehne fruit powder. Industrial relevance The plant Chaenomeles sinensis (Thouin) Koehne is known locally as “Guang Pi Mu Gua”, one of the Chinese traditional food and drug fruits, has a golden color and with full-bodied fragrance, and is enriched in dietary fibre, organic acid and some biologically active pentacyclic triterpene acids such as oleanolic acid and ursolic acid. Moreover, its yield was very large, e.g. the total yield has over 100,000 tons in 2006 just in Baihe County, Shaanxi, China. So it is very significant to study its processing. Recently, there has also been a rapid development in micron technology applications along with nanotechnology to develop products that explore novel properties in food and drug industries. Physical and functional properties of some Chinese traditional medicines were found to change with particle size during superfine grinding. So, we begin this research.

CuZrAl amorphous alloys prepared by casting and milling

Several preparation methods are available for the production of amorphous alloys. During the experiment described in this paper (Cu58Zr42)100-xAlx (x = 0-14,8; in at%) amorphous alloys were prepared by casting and ball-milling. The ingots were produced by arc melting. Wedge-shaped samples were prepared from the ingots by centrifugal casting into copper mould. The microstructures of these samples were defined by SEM. The amorphous samples were analysed by DSC and the activation energy of the crystallization processes was calculated from the measured temperatures. The master alloys of identical composition were milled by ball-mill for different periods of time. The powders were analysed by XRD in order to define the amorphous fractions.

Direct Mechanochemical Synthesis of Nanocrystalline NiWO4

The possibilities of mechanochemical activation as a successful route for direct synthesis of NiWO4 have been studied. A stoichiometric mixture of NiO and WO3 in a 1:1 molar ratio was subjected to intense mechanical treatment in air using a planetary ball mill for different periods of time. The phase and structural transformations were monitored by X-ray diffraction (XRD), infrared spectroscopy (IR), and X-ray photoelectron spectroscopy (XPS). It was found that 7.5 h of milling of the reagents leads to complete crystallization of single nanostructured phase NiWO4 at room temperature.

Mechanochemical Synthesis of Nanocrystalline Nickel Molybdates.

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Mechanochemical synthesis of nanocrystalline nickel molybdates

The aim of this study is to establish the possibilities of mechanochemical activation as a successful route for the preparation of NiMoO 4 catalysts. A stoichiometric mixture of NiO and MoO 3 in a 1:1 molar ratio was subjected to intense mechanical treatment in air using a planetary ball mill for different periods of time. The phase and structural transformations were monitored by X-ray diffraction (XRD) and infrared spectroscopy (IR). The obtained products were analyzed by X-ray photoelectron spectroscopy (XPS). It was found that 5 h milling of the reagents led to complete crystallization to single-phase α-NiMoO 4 at room temperature. Mechanochemical activation for 2.5 h resulted in a high-temperature β-NiMoO 4 phase under very mild experimental conditions.

Si–Mn composite anodes for lithium ion batteries

Si–Mn composites were prepared by mechanical ball milling for different periods. The microstructure and electrochemical performance of the composites were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and electrochemical methods. XRD showed that the materials prepared by ball milling were composites consisting of Si and Mn powders. The particle size was about 1 μm from the SEM images. The Si–Mn composites after 60 h ball milling showed the best performance, especially when annealed at 300 °C for 2 h, which had a reversible capacity of 455 mAh g −1 and an initial Coulomb efficiency of 52%. Mn acted as an inactive buffer of the Si–Mn composite electrode and enhanced the cyclic performance of the active center (Si). It was also observed that nanosized Si–Mn particles merged together after the insertion/extraction of lithium ions, which decreased the electric contact between the active materials and copper substrate.

ＣｄＳ粉末の粉砕に伴う光電導性の変化 ＣｄＳ粉末の表面状態の変化

The effect of ball milling on the surface condition of CdS powders was investigated. The sample powders were precipitated from aqueous solution of cadmium sulfate. The mean particle sizes of the precipitates were about 10 and 2μm. The sample powders were ground in an alumina ball mill for different periods from 30min to 240hr. In the early stage of the grinding process, the particle size of the specimen having the initial particle size of 10μm decreased rapidly to about 2μm and it did not decrease any more even if grinding time was prolonged. On the other hand, the particle size of the specimen having the initial particle size of 2μm did not decrease any more. However, the degree of structural imperfections increased with increasing grinding time for both specimens.Using an interdigital electrode, the decrease in photocurrent associated with an adsorption of oxygen has been measured. The magnitude of the decrease in the photocurrent of ground CdS powders became larger with increasing grinding time. This suggests that the structural imperfections, generated by ball milling, act as adsorption sites for oxygen molecules.Corona-charging potentials of ground CdS powders have been measured as a function of relative humidity. The initial surface potentials decreased with increasing grinding time over a whole range of relative humidity for all specimens. This is attributable to a decrease in apparent resistivity of the powder layer, which is associated with an increase in adsorbed moisture. The adsorption of ambient moisture is enhanced by the ball milling.

Effects of Grinding on the Photoconductive Properties of CdS Powder

The effects of ball milling on the photoconductivity process in ground CdS powders were investigated. A sample powder was prepared from aqueous solution of cadmium sulphate. The powder was found to have a hexagonal structure, and the mean particle size was about 10μm. The powder was ground in an alumina ball mill for different periods from 30min to 30hr, In the early stage of the grinding process, the mean particle size decreased rapidly to about 2μm and it did not decrease any more even if grinding time was increased.The X-ray analysis showed the following results: (1) The transformation of CdS from hexagonal to cubic does not take place during grinding by using the alumina ball mill. (2) The degree of lattice distortion increases with increasing grinding time.Reflectance of the ground CdS powders decreased slightly with grinding time in the wavelength region of 550∼700nm. This reduction could be explained by an increase in lattice distortion.Using an interdigital electrode, the spectral response of photoconductivity, the photocurrent-light intensity characteristic and the decay of photocurrent were measured for the ground CdS powders. The photocurrent decreased considerably in the early stage of the grinding process, and then decreased gradually with increasing grinding time. This change was similar to the change of the mean particle size with grinding time. As the result of this similarity, it became evident that the considerable decrease in photocurrent by grinding is atributable to an increase in interparticle contact resistance of pressed CdS powders.The photoconductivity spectral response of the ground CdS powders showed a larger decrease in the short wavelength region than in the long wavelength region. This could be explained by structural imperfections generated near the CdS surface. The imperfections generated by grinding acted as the recombination centers and lowered the photosensitivity, especially in the short wavelength region. It was found also that the recombination centers facilitated the decay of photoconductivity. Moreover imperfections could also act as the trapping centers and lower the speed of response.

Effect of wet grinding on the particle size distribution and base exchange capacity of a non-plastic china clay

A sample of a coarse variety of china clay was ground in a laboratory ball mill for different periods. Particle size distribution and b.e.c. of the different sampled obtained were measured. It was found that by grinding, the coarse particles were considerably reduced in size whereas fine particles were not appreciably affected. A linear relation between b.e.c. and specific surface calculated from particle size distribution data was obtained.