• Resources Recycling
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• v.19 no.4
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• pp.51-57
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• 2010

As a recycling of Si sludge from Si wafer process, a Si-SiC-CuO-C composite material was synthesized and investigated as an anode material for lithium batteries. The Si sludge consisted of Si, SiC, machine oil, and metallic impurities. The oil and metal impurities was removed by organic washing, magnetic separation, and acid washing. The Si-SiC-CuO-C composite from the recovered Si-SiC mixture was prepared by high-energy mechanical milling. According to the electrochemical tests such as charge-discharge capacity and cycling behavior, it showed the improved cycle performance. The SiC and CuO-related phases were presumed to restrain the volume expansion of the anode and Fe, however, should be removed below 10 ppm prior to synthesis of the composite because it caused the capacity loss of the active material itself.

• Journal of the Korean Society for Heat Treatment
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• v.9 no.1
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• pp.1-11
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• 1996

Mechanical alloying is an effective process to finely distribute inert dispersoids in an Al-TM(TM is a transition metal) system. It has been considered that high melting point aluminides are formed by precipitation from supersaturated Al(Ti) powder. This analysis is based on the fact that much higher content of TM than the solubioity can be dissolved in alpha aluminum during the high energy ball milling. Thus, decomposition behavior of Ti in the Al(Ti) was considered very important. But it is confirmed that the higher portion of Ti than Al(Ti) solid solution is existed as nano-sized Ti particles in the MA powders by high energy ball nilling from the XRD spectrum and TEM analysis in this study. Therefore, the role of undissolved TM particles affect the formation of aluminides should be suitably considered. In this study, we present experimental observation on the formation of $Al_3Ti$ fron mechanical alloyed Al-Ti alloys in the hyperperitectic region. This study showed that, in the mechanically alloyed Al-20wt%Ti specimen, intermediate phase of cubic $Al_3Ti$ and tetragonal $Al_{24}Ti_8$ formed at $300{\sim}400^{\circ}C$ and $400{\sim}500^{\circ}C$, respectively, before the MA state reaches to equilibrium at higher temperatures. The formation behavior of $Ll_2-Al_3Ti$ is interpreted by interdiffusion of Al and Ti in solid state based on the fact that large amount of nano-sized Ti particles exist in the milled powder. Present analysis indicated undissolved Ti particles of nanosize should have played an important role initiation the formation of $Al_3Ti$ phase during annealing.

• Korean Journal of Materials Research
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• v.10 no.10
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• pp.715-720
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• 2000

By the mechanical alloying method. Ni-WC composite materials were prepared to improve the deformation-resistance for creep and sintering of Ni-anode at the operating temperature of $650^{\circ}C$. Mechanically alloyed powder w was initially fabricated by ball milling for 80hr, and then amorphization was occurred by the destruction of ordered crystals based on XRD analysis. In order to investigate the electrochemical performance and sheet characteristics of Ni-WC anode, tape casting process was adopted. Finally, the obtained sheet thickness of Ni- we after sintering at $1180^{\circ}C$ for 60 minutes in $H_2$ atmosphere was O.9mm and the average pore size was $3~5{\mu\textrm{m}}$ with porosities of 55%. The second phase was not observed in Ni- W matrix while W particles were finely and uniformly distributed in Ni matrix. This fine and uniform distributed W particles in Ni matrix are expected to enhance the mechanical properties of Ni anode through the dispersion and solid solution hardening mechanisms.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.8
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• pp.847-853
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• 2011

In this study, a hybrid powder-extrusion process involving the control of temperature dwelling time for improving the formability of Zn-22Al powder was developed and the effect of dwelling time on the mechanical properties of a spur gear with a pitch circle having a diameter of 1.8 mm was investigated. General extrusion experiments were carried out at different temperatures such as 290, 300, and $310^{\circ}C$. Spur gears with good qualities and without any surface defects were obtained in the case of extrusion temperature of $310^{\circ}C$ and ball-milling duration of 32 h. The Vickers hardness distribution was non-uniform, and after the sintering process, an internal crack was generated because of the different deformation energy between gear central part and teeth. To overcome the abovementioned problems, research on controlling the dwelling time of the extrusion temperature in the powder-extrusion process was carried out. Good-quality spur gears were obtained when the dwelling time was 15 min.

• Korean Journal of Materials Research
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• v.8 no.4
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• pp.328-336
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• 1998

In metal-carbon system with no mutual solubility between matrix and alloying elements as solid or liquid phases, Cu-C-X nanocomposite metal powders were prepared by high energy ball milling for solid-lubricating bronze bearings. Elemental powder mixtures of Cu-lOwt.%C- 5wt. %Fe and Cu- lOwt. %C- 5wt. %Al were mechanically alloyed with an attritor in an argon atmosphere, and then microstructural evolution of the Cu-C-X nanocomposite metal powders was examined. It has been found that after 10 hours of MA, the approximately 10$\mu\textrm{m}$ sized Cu-C- X nanocomposite metal powders can be produced in both compositions. Morphological characteristics and microstructural evolution of the Cu-C-X powders have shown a similar MA procedure compared to those of metal-metal system. As a result of X - ray diffraction analysis, diffraction peaks of Cu and C were broaden and peak intensities were decreased as a function of MA time. Especially, the gradual disappearance of C peaks in the X- ray spectra is proved to be due to the lower atomic scattering factor of C. The calculated Cu crystallite sizes in Cu- C- X nanocomposite metal powders by Williamson- Hall equation were about lOnm size, on the other hand, the observed ones by TEM were in the range of 10 to 30nm.

• Journal of Powder Materials
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• v.20 no.4
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• pp.269-274
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• 2013

The present work investigated the dispersion behavior of $Y_2O_3$ particles into AISI 316L SS manufactured using laser cladding technology. The starting particles were produced by high energy ball milling in 10 min for prealloying, which has a trapping effect and homogeneous dispersion of $Y_2O_3$ particles, followed by laser cladding using $CO_2$ laser source. The phase and crystal structures of the cladded alloys were examined by XRD, and the cross section was characterized using SEM. The detailed microstructure was also studied through FE-TEM. The results clearly indicated that as the amount of $Y_2O_3$ increased, micro-sized defects consisted of coarse $Y_2O_3$ were increased. It was also revealed that homogeneously distributed spherical precipitates were amorphous silicon oxides containing yttrium. This study represents much to a new technology for the manufacture and maintenance of ODS alloys.

• Korean Journal of Metals and Materials
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• v.49 no.2
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• pp.174-179
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• 2011

We investigated the surface morphology changes of a lithium/sulfur battery using multi-walled canbon nanotube added sulfur electrode during charge-discharge cycling. The Li/S cell showed the first discharge capacity of 1286 mAh/g-S, which utilized is 71% of the theoretical value. It decreased to 328 mAh/g-S at the 100th cycle, which corresponds to about 19% utilization of the total sulfur in the cathode. The spherical lumps of the reaction product were observed on the surface of the sulfur electrode. This material was verified as lithium sulfide by X-ray diffraction measurement. The pores in the separator were filled with reaction product. Thus the diffusion of the $Li^+$ ion decreased, which resulted in the decreased capacity of the Li/S cell.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2000.04a
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• pp.9-10
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• 2000

An important business-field of world-wide steel-industry is the coating of thin metal-sheets with zinc, zinc-aluminum and aluminum based materials. These products mostly go into automotive industry. in particular for the car-body. into building and construction industry as well as household appliances. Due to mass-production, the processing is done in large continuously operating plants where the mostly cold-rolled metal-strip as the substrate is handled in coils up to 40 tons unwind before and rolled up again after passing the processing plant which includes cleaning, annealing, hot-dip galvanizing / aluminizing and chemical treatment. In the liquid Zn, Zn-AI, AI-Zn and AI-Si bathes a combined action of corrosion and wear under high temperature and high stress onto the transfer components (rolls) accounts for major economic losses. Most critical here are the bearing systems of these rolls operating in the liquid system. Rolls in liquid system can not be avoided as they are needed to transfer the steel-strip into and out of the crucible. Since several years, ceramic roller bearings are tested here [1.2], however, in particular due to uncontrollable Slag-impurities within the hot bath [3], slide bearings are still expected to be of a higher potential [4]. The today's state of the art is the application of slide bearings based on Stellite\ulcorneragainst Stellite which is in general a 50-60 wt% Co-matrix with incorporated Cr- and W-carbides and other composites. Indeed Stellite is used as the bearing-material as of it's chemical properties (does not go into solution), the physical properties in particular with poor lubricating properties are not satisfying at all. To increase the Sliding behavior in the bearing system, about 0.15-0.2 wt% of lead has been added into the hot-bath in the past. Due to environmental regulations. this had to be reduced dramatically_ This together with the heavily increasing production rates expressed by increased velocity of the substrate-steel-band up to 200 m/min and increased tractate power up to 10 tons in modern plants. leads to life times of the bearings of a few up to several days only. To improve this situation. the Mechanical Alloying (MA) TeChnique [5.6.7.8] is used to prOduce advanced Stellite-based bearing materials. A lubricating phase is introduced into Stellite-powder-material by MA, the composite-powder-particles are coated by High Energy Milling (HEM) in order to produce bearing-bushes of approximately 12 kg by Sintering, Liquid Phase Sintering (LPS) and Hot Isostatic Pressing (HIP). The chemical and physical behavior of samples as well as the bearing systems in the hot galvanizing / aluminizing plant are discussed. DependenCies like lubricant material and composite, LPS-binder and composite, particle shape and PM-route with respect to achievable density. (temperature--) shock-reSistibility and corrosive-wear behavior will be described. The materials are characterized by particle size analysis (laser diffraction), scanning electron microscopy and X-ray diffraction. corrosive-wear behavior is determined using a special cylinder-in-bush apparatus (CIBA) as well as field-test in real production condition. Part I of this work describes the initial testing phase where different sample materials are produced, characterized, consolidated and tested in the CIBA under a common AI-Zn-system. The results are discussed and the material-system for the large components to be produced for the field test in real production condition is decided. Outlook: Part II of this work will describe the field test in a hot-dip-galvanizing/aluminizing plant of the mechanically alloyed bearing bushes under aluminum-rich liquid metal. Alter testing, the bushes will be characterized and obtained results with respect to wear. expected lifetime, surface roughness and infiltration will be discussed. Part III of this project will describe a second initial testing phase where the won results of part 1+11 will be transferred to the AI-Si system. Part IV of this project will describe the field test in a hot-dip-aluminizing plant of the mechanically alloyed bearing bushes under aluminum liquid metal. After testing. the bushes will be characterized and obtained results with respect to wear. expected lifetime, surface roughness and infiltration will be discussed.

• Journal of Hydrogen and New Energy
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• v.10 no.1
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• pp.27-40
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• 1999

By hydrogen induced planetary ball milling process, $Mg_2NiH_x$ hydrogen absorbing materials were successfully alloyed mechanically at room temperature, using pure Mg and Ni chips. The Mg & Ni chips were mixed by 45:55 weight ratio and Mechanical Alloying(M.A.) was carried out : the hydrogen pressure induced in the jar was varied from 1 to 20 bars and the M.A. times were 24 and 48 hours. The XRD results revealed that the homogeneous $Mg_2NiH_x$ was incresed with the hydrogen pressure increasing, and that $MgH_x$ was detected by unalloyed Ni chips. The shape and size of the mechanically alloyed particles didn't depend on the induced hydrogen pressure. The results of TGA showed that the hydrogen quantities of $Mg_2NiH_x$ has 1.1~3.9 wt%.

• Journal of Powder Materials
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• v.24 no.2
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• pp.133-140
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• 2017

This study investigates the oxidation properties of Fe-14Cr ferritic oxide-dispersion-strengthened (ODS) steel at various high temperatures (900, 1000, and $1100^{\circ}C$ for 24 h). The initial microstructure shows that no clear structural change occurs even under high-temperature heat treatment, and the average measured grain size is 0.4 and $1.1{\mu}m$ for the as-fabricated and heat-treated specimens, respectively. Y-Ti-O nanoclusters 10-50 nm in size are observed. High-temperature oxidation results show that the weight increases by 0.27 and $0.29mg/cm^2$ for the as-fabricated and heat-treated ($900^{\circ}C$) specimens, and by 0.47 and $0.50mg/cm^2$ for the as-fabricated and heat-treated ($1000^{\circ}C$) specimens, respectively. Further, after 24 h oxidation tests, the weight increases by 56.50 and $100.60mg/cm^2$ for the as-fabricated and heat-treated ($1100^{\circ}C$) specimens, respectively; the latter increase is approximately 100 times higher than that at $1000^{\circ}C$. Observation of the surface after the oxidation test shows that $Cr_2O_3$ is the main oxide on a specimen tested at $1000^{\circ}C$, whereas $Fe_2O_3$ and $Fe_3O_4$ phases also form on a specimen tested at $1100^{\circ}C$, where the weight increases rapidly. The high-temperature oxidation behavior of Fe-14Cr ODS steel is confirmed to be dominated by changes in the $Cr_2O_3$ layer and generation of Fe-based oxides through evaporation.