Mill In Order Research Articles

GUIDELINES FOR THE CONSTRUCTION OF A BALL MILL FOR GRINDING SOLIDS IN THE LABORATORY

In this paper, we show the construction of a low-cost, high-quality ball mill for obtaining finely divided powders, with the goal of presenting guidelines for achieving the best results for the milling process. This equipment allows for the adjustment of the size of the mill in order to process different quantities of material. The construction of mechanical and electrical components that provide increased efficiency, the choice of milling medium, and frequent problems experienced with homemade ball mills are discussed.

Mills Can't Think: Leibniz's Approach to the Mind-Body Problem

In the Monadology Leibniz has us imagine a thinking machine the size of a mill in order to show that matter can't think. The argument is often thought to rely on the unity of consciousness and the notion of simplicity. Leibniz himself did not see matters this way. For him the argument relies on the view that the qualities of a substance must be intimately connected to its nature by being modifications, limitations of its nature. Leibniz thinks perception is not a modification of matter because it is active and matter is passive. At the same time, there are traces in Leibniz of a different argument that relies on the notion of internal action, which may involve the notion of simplicity. Critics have sometimes charged that the Mill Argument is an argument from ignorance, but Leibniz was aware of this problem and made clear that he did not make that mistake.

서스펜션 플라즈마 용사를 이용한 이트리아 안정화 지르코니아 (7.5 wt% Y2O3-ZrO2) 코팅 증착 및 특성

Yttria-stabilized zirconia (YSZ) coatings are fabricated via suspension plasma spray (SPS) for thermal barrier applications. Three different suspension sets are prepared by using a planetary mill as well as ball mill in order to examine the effect of starting suspension on the phase evolution and the microstructure of SPS prepared coatings. In the case of planetary-milled commercial YSZ powder, a deposited thick coating turns out to have a dense, vertically-cracked microstructure. In addition, a dense YSZ coating with fully developed phase can be obtained via suspension plasma spray with suspension from planetary-milled mixture of <TEX>$Y_2O_3$</TEX> and <TEX>$ZrO_2$</TEX>.

Green Extraction: Enhanced Extraction Yield of Asiatic Acid from Centella asiatica (L.) Nanopowders

Nanopowders of Centella asiatica (L.) were produced using planetary ball mill in order to investigate the differences of water extraction yield of asiatic acid as compared to micropowders of Centella asiatica. Effect of extraction time (20–60 min) on extraction yield of asiatic acid from Centella asiatica was examined. Results showed that water extraction of asiatic acid using Centella asiatica nanopowders exhibits was almost 50% higher extraction yield with 7.09 mg/g as compared to the micropowders of Centella asiatica. It was concluded that nanopowders contributed in enhancing water extraction yield of asiatic acid as compared to micropowders. Thereby utilizing nanopowders in water extraction could improve the extraction of asiatic acid via clean, eco-friendly, and less expensive process.

Ex situ Al–Al2O3 ultrafine grained nanocomposites produced via powder metallurgy

Commercial purity aluminum powder and Al2O3 nano-particles were ground by high energy ball milling in order to embed and disperse the ceramic phase in the soft metal matrix. The composite powders were consolidated by ECAP. SEM and EBSD analysis were performed to investigate the microstructure of metal matrix and the distribution of reinforcement. The specific powder metallurgy route proposed in this work revealed to be an effective method for the production of ex situ ultra-fine grained matrix nano-composites characterized by homogeneous dispersion of discrete nano-particles and by improved hardness.

Preparation of red-emitting phosphor (Y,Gd)BO3:Eu3+ by high temperature ball milling

The red-emitting phosphor (Y,Gd)BO3:Eu3+ was prepared by high temperature ball milling in order to improve the color purity and decrease the calcining temperature. The phosphor was characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and luminescence spectra. The results showed that the phosphor(Y,Gd)BO3:Eu3+ could be obtained at 600 °C, i.e. at a much lower temperature in contrast to conventional solid state reaction. The phosphor can be effectively excited by VUV radiation at 147 nm. In its emission spectrum, the strongest peak at 628 nm correlating to red emission was ascribed to the forced electric dipole transition 5D0→7F2 of Eu3+ ions. Its chromaticity coordinates (CIE) were calculated to be x=0.65, y=0.35. Significantly, the intensity ratio of Y0.65Gd0.1Eu0.25BO3 phosphors of the red (5D0→7F2) to the orange (5D0→7F1) transition (R/O value) is 2.39, which is higher than 2.15 of the phosphor prepared by solid state reaction. The color purity was significantly improved. The particles with narrow distribution range and spherical morphology were approximately 200 nm in size. The luminescent properties of the (Y,Gd)BO3:Eu3+ sample with 25 mol% doping concentration of Eu3+ were optimal. Therefore, high temperature ball milling is of help to (Y,Gd)BO3:Eu3+ phosphor for improving the color purity and decreasing the calcining temperature in the future applications.

Microstructure and martensitic transformation in Si-coated TiNi powders prepared by ball milling

Si was coated on the surface of Ti–49Ni (at%) alloy powders by ball milling in order to improve the electrochemical properties of the Si electrodes of secondary Li ion batteries and then the microstructure and martensitic transformation behavior were investigated by means of scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and differential scanning calorimetry (DSC). Ti–Ni powders coated with Si were fabricated successfully by ball milling. As-milled powders consisted of highly deformed Ti–Ni powders with the B2 phase and amorphous Si layers. The thickness of the Si layer coated on the surface of the Ti–Ni powders increased from 3–5μm to 10–15μm by extending the milling time from 3h to 48h. However, severe contamination from the grinding media, ZrO2 occurred when the ball milling time was as long as 48h. By heating as-milled powders to various temperatures in the range of 673–873K, the highly deformed Ti–Ni powders were recovered and Ti4Ni4Si7 was formed. Two-stage B2–R–B19′ transformation occurred when as-milled Si-coated Ti–49Ni alloy powders were heated to temperatures below 873K, above this temperature one-stage B2–B19′ transformation occurred.

Synergistic hydrogen desorption of HCS MgH2 + LiAlH4 composite

MgH2 was prepared by HCS (hydriding combustion synthesis) method, and the as-prepared product (HCS MgH2) was further combined with LiAlH4 by mechanical milling in order to form a new composite of HCS MgH2 + LiAlH4. Structural and hydrogen storage properties of the HCS MgH2 + LiAlH4 composite have been investigated systematically by XRD (X-ray diffraction), SEM (scanning electron microscope), DSC (differential scanning calorimetry) and hydrogenation/dehydrogenation measurements. A mutual destabilization effect has been observed between HCS MgH2 and LiAlH4 during hydrogen desorption. The dehydrogenation mechanism of the composite has been revealed. Compared with commercial MgH2 (Com MgH2) + LiAlH4 composite, the HCS MgH2 + LiAlH4 composite shows more pronounced synergistic hydrogen desorption with notably decreased dehydrogenation temperature owing to the unique microstructures of the HCS MgH2, which may provide favorable channels for diffusion of hydrogen atoms and promote synergistic hydrogen desorption of the composite. The dehydrogenation barrier of the HCS MgH2 + LiAlH4 composite is lower than that of the Com MgH2 + LiAlH4 composite. Moreover, the HCS MgH2 + LiAlH4 composite exhibits fast re-hydrogenation kinetics in the first two cycles.

微小径エンドミル加工における溝加工精度に関する研究 (第2報)

In previous paper, groove position error and groove warp are substantially generated in micro tool-width end milling process. Therefore, finish milling following the tool-width milling is required to append for improving the groove accuracy. In this paper, it is discussed experimentally how to mill on side walls with position error or groove warp on finish milling. It is made clear that up-milling is less influential on the position error on a side wall than down-milling, because cutting force in down-milling is more cumulative in forming a chip segment from engaging rotating angle to a side wall angle(θ=π), although cumulative cutting force to mill a side wall can be ignored in up-milling. As the above-mentioned reason, up-milling is recommended as finish milling in order to remove a position error and groove warp on side walls.

UNSAFE ACT AS THE RISK FACTORS OF ACCIDENTS IN USING MILL IN ROOF TILE INDUSTRY AT PEJATEN VILLAGE TABANAN REGENCY

The use of mill and hand press machines had been increased the productivity ofroof tile home industry at Pejaten Village Tabanan Regency. But the increased ofproductivity followed by increased of working accidents. Many effort had been done toreduced the accident such as equipped the mill machine with machine’s cover, footprotective devices, and training to the new employees; but, the accident still happen.Although the incident of accident was lower but the disability was severed such as loss ofhand, loss oh finger, or other physical defects of the body part. Such physical defectscaused a serious effect on worker’s daily lives and social activities. To find out the unsafeacts as the risk factors of accident, a retrospective study was done using interview and onthe spot observation to the milling process. The results are found: there are three riskfactors contributed to the accidents, namely: the human factor, the tools and theenvironment. The human factor contributed highest one for the accident. From humanfactors it was found that there are many unsafe acts, such as: careless, going up to theupper inlet of mill to push mixing raw material with foot or hand, moving the millwithout turn off the machine, cleaning the mill without turn off the mill, taking out thestone which trapped the rollers using hand, operating the machine without guarding,working with tired condition, working without knowing the operation procedure, withouttraining, improver lighting, working without personal protective devices, etc. The highestincidents come from pushing the raw materials on inlet of mill in order to speed-up themilling process. To solve the problems some actions must be done such as providing themill with the appropriate equipments; by doing so, the operator can push the materialsafely to speed-up the mill process, turn off the machine before cleaning, appropriatetraining before operating of mill, using the personal protective devices, and doing goodhouse keeping and inspection, regularly.

Post-combustion capture of CO2 at an integrated steel mill – Part I: Technical concept analysis

In this study different possibilities for applying post-combustion capture at an integrated steel mill in order to reduce carbon dioxide emissions were studied. Implications of different amounts of CO2 captured, different solvents for post-combustion capture and different heat supply options for solvent regeneration to the energy balance and greenhouse gas emissions of the steel mill are compared to that of the base case for the steel mill.The case study is based on Ruukki Metals Ltd.’s Raahe steel mill that is situated on the coast of the Gulf of Bothnia. It is the largest integrated steel mill in the Nordic countries producing hot rolled steel plates and coils. It is also the largest CO2 point source in Finland emitting approximately 4Mt/year.Carbon capture processes were modelled using Aspen Plus process modelling software and results were used to estimate the potential for reducing CO2 emissions at an integrated steel mill from a plant operator's point of view. Different heat integration options and heat utilization scenarios were investigated. The heat available for solvent regeneration varied between these heat utilization scenarios and thus partial capture of CO2 was investigated with the CO2 amount captured depending on the heat available for solvent regeneration in the different case studies.The results of the study show a significant CO2 reduction potential using CCS. Approximately 50–75% of the emissions from the site could be captured using post-combustion capture. Capturing a larger amount of emissions would be technically less feasible due to the large number of small stacks around the large, integrated steel mill site.

Bovine Bone Processing for Biofilter Application

This work involves the processing of bovine bone for use as biofilter collector of heavy metals in water. Before processing, it was necessary to clean the bone selected for removing the organic material adhered thereto. Drying was done in weathered during 18 days. Then the bones were calcined at a constant temperature of 750°C for 6 hour. The bone grinding was performed by means of an analytical mill in order to obtain a finer grain size. Once processed, the bovine bone powder was characterized by X-ray diffraction and fluorescence analyses. The results showed that the powder phase is less crystalline hydroxyapatite, when compared to highly crystalline synthetic hydroxyapatite, which favors the sorption capacity of lead by bovine bone.

Effect of prior mechanical refining on biobleaching of wheat straw pulp with laccase/xylanase treatment

Wheat straw pulp was mechanochemically processed in a PFI mill in order to improve the effect of laccase/xylanase system (LXS) treatment before bleaching. The delignification and bleachability of the prepared pulp were investigated. The delignification of the prepared pulp could be enhanced with the mechanochemical processing (refining) and LXS treatment. The delignification was increased by 29.8% with refining 7000 revolutions and 5 IU/g enzyme dosage. The LXS treatment after the mechanochemical process could save 28.6% effective usage of chlorine in the subsequent hypochlorite bleaching process, compared with the traditional bio-bleaching. The crystallinity of cellulose was increased by the co-treatment with mechanochemistry and LXS treatment. This result was further supported by the observations from SEM. This co-treatment with mechanochemistry and bio-treatment enhanced the delignification and bleachability of pulp.

Investigations on Interaction between Recrystallization and Precipitation at Finishing Steps of Seamless Tube Rolling

Conventional controlled rolling is normally used in a hot strip mill in order to refine the microstructure and, consequently, to meet a good combination of mechanical strength and toughness in low carbon steels. Nb microalloying are used for this purpose once this rolling technique requires the occurrence of strain induced precipitation before that any recrystallization process takes place. In a hot strip mill, the transfer time between roughing and finishing steps is considered fast enough to keep all Nb, previously solubilized in plate furnace, in solid solution just before finishing. As a consequence, the thermodynamic driving force required for strain induced precipitation remains high, accelerating its kinetics and preventing the occurrence of recrystallization. On the other hand, in a seamless tube rolling, the transfer time between roughing and finishing steps is about 20 times longer than in a hot strip mill. As a consequence, Nb can precipitate in the recrystallized austenite after roughing, decreasing the driving force for strain induced precipitation at finishing. Transmission electron microscopy investigations on samples simulating the material just before finishing rolling in a seamless tube mill show that both grain boundary precipitation and co-precipitation on TiN particles takes place during transfer time. Based on these findings, this paper discusses the effect of long times after roughing steps on the driving force for strain induced precipitation at finishing rolling in seamless tube. Thermo-Calc software was used to evaluate the possible amount of Nb that remains in solid solution just before finishing. Due to previous precipitation, the driving force to be considered in the Dutta-Sellars equations for onset of precipitation decreases and a comparison between recrystallization and precipitation curves shows that recrystallization takes place before the start of strain induce precipitation.

FABRICATION AND CHARACTERIZATION OF AL-AL4C3 NANOCOMPOSITE BY MECHANICAL ALLOYING

Aluminum carbide ( Al 4 C 3) seems to be an ideal reinforcement for producing aluminum matrix composites. Al 4 C 3 has high hardness and shear strength as well as a high melting point. The dispersion of Al 4 C 3 particles in the matrix produces a pinning effect that reduces aluminum grain growth, which improves the mechanical properties. In this study, aluminum powders were mixed with 4.5 wt.% graphite and mechanically alloyed using a high-energy ball mill in order to produce Al - Al 4 C 3 nanocomposite. The structural evaluation of powder particles after different milling times was studied by X-ray diffractometry, scanning electron microscopy and microhardness measurements. The aluminum crystallite size estimated with broadening of XRD peaks by Williamson–Hall formula. XRD results suggested that the grain size of aluminum decreased to nanometer range (30 nm) during ball milling. No Al 4 C 3 formed during the mechanical alloying process. Milled powders were then annealed at 300-600 °C for 1 h under argon atmosphere. Annealing at temperatures higher than 300 °C led to formation of Al 4 C 3 phase which increased as annealing temperature increased. Aluminum grain size remained in nanometer range after annealing process. The microhardness of powder particles increased after annealing. Both effects are due to the formation of nanosized Al 4 C 3 particles.

Study on Machinability of Laser Sintered Materials Fabricated By Layered Manufacturing System: Influence of Different Hardness of Sintered Materials

This paper investigates machinability of laser sintered materials fabricated by layered manufacturing system. Different types of sintered materials; chromium molybdenum (SCM) sintered material and maraging steel (MAS) sintered material were fabricated by using selective laser melting (SLM) method. Measurement of cutting force and cutting temperature were carried out by using ball end mill in order to understand the influence of different hardness of sintered materials on machinability. Bulk carbon steel (JIS S55C) was selected as reference steel. Experimental results show that MAS sintered material is difficult to machine material where cutting force of MAS sintered material was higher than SCM sintered material. However, even though MAS sintered material has higher hardness than SCM sintered material, cutting temperature was low due to high thermal conductivity. From these results, MAS sintered material can be considered as good material to produce mold due to its high hardness and good machinability.

The effect of heat treatment and re-calcination on magnetic properties of BaFe12O19/Fe3O4 nano-composite

In this study a mixture of barium hexaferrite (BaFe12O19) and graphite was subjected to intensive milling in a planetary ball mill in order to synthesize BaFe12O19/Fe3O4 magnetic nano-composite. The effects of milling time and post-synthesis heat treatment on the powder characteristics were investigated using XRD, VSM and HRTEM techniques. XRD results showed that barium hexaferrite partially reduced during high-energy ball milling and nano-composite of BaFe12O19/Fe3O4 was obtained after 15h milling of the initial mixture. Analysis of the 40h milled and then heat-treated samples revealed that reduction of iron oxides proceeded at temperatures above 650°C. The most intensive peaks of α-Fe were observed in XRD patterns of the samples heat treated at 850 and 950°C. Magnetic property measurements showed that saturation magnetization of the milled sample increased considerably and coercivity decreased by heat treating at 950°C. Re-calcination of the aforementioned sample resulted in an increase in coercivity value to 3444.62Oe. HRTEM image showed nano-crystalline Fe3O4 in the structure of 40h milled sample.

Modeling and Simulation of the Dynamics of the Milling of Ball End Milling

A dynamic modal of the milling of ball end milling is presented for the simulation and analyzing the influence of the milling parameters on milling in order to avoid the vibration. The milling cutter and constrains are simplified to be a system with the two modes of vibration, the modal is developed considering effective cutting area of the cutting edge and regenerative effect, which directly reflects the cutter-in and the cutter-out. The mode testing and identifying determine the equation coefficients. It is found that reducing the milling depth can improve the stability and avoid self-excited vibration milling when the depth less than the critical milling depth, the frequency of the milling system will change while changing the rotate speed of the spindle, the self-excited is prone to occur when the frequency is close to the natural frequency. The results of simulation are benefit of the milling and optimal design of the parallel machine tools.

A new approach to enhance oral bioavailability of Silybum Marianum dry extract: Association of mechanochemical activation and spray congealing

The aim of the work was to produce a delivery system for Silybum Marianum dry extract with enhanced oral bioavailability by combining two technologies (mechanochemical activation and spray congealing). Initially, the active was coground with sodium croscarmellose in a planetary mill in order to reach an activated state more prone to dissolution. DSC, XRD, FT-IR and LD analyses showed the formation of nanosized particles of dry extract, with reduced degree of crystallinity of the main crystalline flavolignans (silybine A and B). Then, microparticles containing the activated coground and, as comparison, the corresponding physical mixture of extract and polymer and the dry extract alone were produced by spray congealing technology using Gelucire ® 50/13 as a hydrophilic low m.p. carrier. Microparticles containing the activated coground were produced spherical in shape, achieved satisfactory yield and high encapsulation efficiency. These microparticles, in addition to a favourable in vitro solubilisation kinetic, in a preliminary in vivo study in five rats demonstrated their ability to improve very significantly the oral bioavailability of the main flavolignans of Silybum Marianum dry extract (silybin A and B). These results suggested that the association of mechanochemical activation and spray congealing could be considered an innovative and very useful approach to the oral delivery of Silybum Marianum. Furthermore, for the first time the possibility of successfully applying the spray congealing technology for the preparation of a herbal drug delivery system was shown.

Densification of additive-free polycrystalline β-SiC by spark-plasma sintering

Additive-free β-SiC nanopowders were densified by spark-plasma sintering in the temperature range 1650–2200 °C, holding time 1–30 min, and pressure 50–150 MPa. The starting nanopowder was further refined and mechanically activated by ball milling in order to promote densification. In a detailed parametric study, temperature, holding time, and/or pressure were varied to investigate their effect on the densification and grain growth during sintering. High densifications were obtained for temperatures greater than 1800 °C. Full densification (98.0 ± 0.6%) was reached at a sintering temperature of 2100 °C. Depending on the sintering conditions, nanostructured materials can be produced with grain sizes between 90 and 100 nm, and microstructured materials with grain sizes between 0.22 and 2.39 μm. Pressure has a major effect on the grain size, it being necessary to use a pressure of 150 MPa to obtain nanostructured materials.