• Journal of the Korean Society for Heat Treatment
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• v.8 no.3
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• pp.222-228
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• 1995

Mechanical alloying behaviour was investigated after adding 6, 8, 12wt% Fe powder into A1 matrix, respectively, in order to develop Al alloy. And the mechanical characteristics of the alloy which was produced by the above method were studied. The hardness and ultimata tensile strength of the material with different compositions were found to be increased with annealing temperatures and holding times. Intermetallic compound of $Al_3Fe$ and carbide of $Al_4C_3$ phases, which were generated from the different compositions during annealing, were found. It was suggested that enhancement of mechanical properties of Al-Fe alloy system was due to the presence of these preapitates that constrained grain growth and blocked dislocation movement in the alloy system.

• Korean Journal of Materials Research
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• v.26 no.8
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• pp.438-443
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• 2016

We developed an Al sputtering process by varying the plasma power, process temperature, and film thickness. We observed an increase of hillock distribution and average diameter with increasing plasma power, process temperature, and film thickness. Since the roughness of a film increases with the increase of the distribution and average size of hillocks, the control of hillock formation is a key factor in the reduction of Al corrosion. We observed the lowest hillock formation at 30 W and $100^{\circ}C$. This growth characteristic of sputtered Al thin films will be useful for the reduction of Al corrosion in the future of the electronic packaging field.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.8
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• pp.974-980
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• 2014

Aluminum acts as sacrificial anode and corrosion protection with Al2O3 formation. If the same current on material for Al ships with steel ships supplies, the more hydrogen would be occurred, that result is bring about over-protection. For this reason, the damage by hydrogen embrittlement leads to the serious accident. In this study, we evaluate electrochemical behavior with rotation speed of 5083-H116 Al alloy material for Al ship in seawater. To examine the electrochemical characteristics with rotation speed and its effects on performance, experiments were conducted at four rotation speed. Results of experiments, the corrosion current density and damage were increased by applying the rotation speed compared to static state.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.8
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• pp.775-779
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• 2006

In this study, sputtered $Al_2O_3$ thin films were evaluated as a passivation layer in the process of InGaN-based blue LEDs in order to improve the brightness of LED lamps. In terms of packaged LED lamps, lamps with $Al_2O_3$ passivation layer emanated higher brightness than those with $SiO_2$ passivation layer, and LED lamps with 90 nm $Al_2O_3$ passivation layer were the brightest among four kinds of lamps. Although lamps with $Al_2O_3$ passivation had a slight increase in operating voltage, their brightness was improved about 13.6 % compare to the lamps made of conventional LEDs without the changes of emitting wavelength.

• Journal of Korea Foundry Society
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• v.1 no.2
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• pp.2-9
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• 1981

Graphite spheroidization and scaling resistance of cast iron containing 5-10% Al were investigated. It is impossible to obtain spheroidal graphite in cast iron containing Al with 8 % and over, but possible to obtain spheroidal graphite even in cast iron with an Al content of about 10 % by increasing Si content. In the scaling test carried out under the heating condition of $950^{\circ}C$ in air for total of 50 hours, the scaling resistance of cast iron containing Al with 8 % and over was remarkably superior, and also spheroidal graphite cast iron was superior to flake graphite cast iron. The scale became thinner more compacts and more protective with increasing Al content.

• Journal of Electrochemical Science and Technology
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• v.3 no.2
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• pp.63-67
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• 2012

We prepared various $LiNi_{0.8}Co_{0.15}Al_{0.05}O_2-LiFePO_4$ mixed-cathode electrodes by changing the content of $LiNi_{0.8}Co_{0.15}Al_{0.05}O_2$ and $LiFePO_4$ used, and we analyzed the electrochemical characteristics of the cathodes. We found that the reversible specific capacity of the cathodes increased and that the capacity retention ratios of the cathodes decreased during cycling as the content of $LiNi_{0.8}Co_{0.15}Al_{0.05}O_2$ increased. Conversely, we found that although the reversible specific capacity of the cathodes decreased because of the material composition, the cycle property of the cathodes increased when the $LiFePO_4$ content increased. We analyzed the thermal stability of the $LiNi_{0.8}Co_{0.15}Al_{0.05}O_2-LiFePO_4$ mixed-material cathodes by differential scanning calorimetry and found that it increased as the $LiFePO_4$ content increased.

• Journal of the Microelectronics and Packaging Society
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• v.24 no.1
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• pp.1-8
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• 2017

Fe-9.8Si-6.0Al mother alloy was manufactured using by Fe-3.5Si recycled scrap and Si powder. And then, soft magnetic alloy powder of $D_{50}$ size and sphere type were prepared by gas atomization process. To obtain the soft magnetic powder of a high aspect ratio, in the first, we conducted the ball milling process for 8 hours. And heat treatment was performed under $650^{\circ}C$, 2 hours and $N_2$ atmosphere condition for reducing the residual stress of the powder. Based on these process, we made around $50{\mu}m$ diameter Fe-9.8Si-6.0Al powder, which morphology and shape was a similar to the commercial Fe-Si-Al powder. Finally, the soft magnetic sheets were prepared by tape casting process using by those powders. The permeability of the tape casting sheet was measured, and we confirmed the possibility of reusing to the soft magnetic materials of Fe-Si electric sheet scrap.

• Bulletin of the Korean Chemical Society
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• v.35 no.2
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• pp.357-364
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• 2014

Size controlled, $LiNi_{0.8}Co_{0.15}Al_{0.05}O_2$ cathode powders were prepared by co-precipitation method followed by heat treatment at temperatures between 750 and $850^{\circ}C$. The synthesized samples are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and electrochemical performance. The synthesized $LiNi_{0.8}Co_{0.15}Al_{0.05}O_2$ after calcined at $750^{\circ}C$ has a good electrochemical performance with an initial discharge capacity of $190mAhg^{-1}$ and good capacity retention of 100% after 30 cycles at 0.1C ($17mAg^{-1}$). The capacity retention of $LiNi_{0.8}Co_{0.15}Al_{0.05}O_2$ after calcined at $750^{\circ}C$ is better than that at 800 and $850^{\circ}C$ without capacity loss at various high C rates. This is ascribed to the minimized cation disorder, a higher conductivity, and higher lithium ion diffusion coefficient ($D_{Li}$) observed in this material. In the differential scanning calorimetry DSC profile of the charged sample, the generation of heat by exothermic reaction was decreased by calcined at high temperature, and this decrease is especially at $850^{\circ}C$. This behavior implies that the high temperature calcinations of $LiNi_{0.8}Co_{0.15}Al_{0.05}O_2$ prevent phase transitions with the release of oxygen.

• Nuclear Engineering and Technology
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• v.46 no.1
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• pp.117-124
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• 2014

The effect of various process variables on the powder properties of recycled $U_3O_8$ from MnO-$Al_2O_3$ doped large grain $UO_2$ pellets and the effect of those recycled $U_3O_8$ powders on the sintered density and grain size of MnO-$Al_2O_3$ doped large grain $UO_2$ pellets have been investigated. The evolution of morphology, size, and BET surface area of the recycled $U_3O_8$ powders according to the respective variation of the thermo-mechanical treatment variables of oxidation temperature, powder milling, and sequential cyclic heat treatment of oxidation and then reduction was examined. The correlation between the BET surface area of recycled $U_3O_8$ powder and the sintered pellet properties of MnO-$Al_2O_3$ doped pellets showed that the pellet density and grain size of doped pellets were increased and then saturated by increasing the BET surface area of the recycled $U_3O_8$ powder. The density and grain size of the pellets were maximized when the BET surface area of the recycled $U_3O_8$ powder was in the vicinity of $3m^2/g$. Among the process variables applied in this study, the cyclic heat treatment followed by low temperature oxidation was a potential process combination to obtain the sinter-active $U_3O_8$ powder.

• Journal of the Korean Ceramic Society
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• v.33 no.11
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• pp.1209-1216
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• 1996

MoSi2-Al2O3 composites were prepared by thermal explosion mode of self-propagating high temperature syn-thesis (SHS) using element powders of MoO3 Mo Si and Al. The combustion products of MoSi2 which have 10, 20, 30 and 40 wt% Al2O3 showed the molten state in the range of Mo to MoO3 6:1-9.5:1, 2:1-8:1, 1:1-5:1, and 1:1-3:1 (molar ratio) respectively. The combustion products which made least seperation the molten phase from the slag phase were in Mo/MoO3=9, 5:1, 8:1, 5:1 and 3:1 (molar ratio) respectively. Particles size of MoSi2 and Al2O3 in the combustion product were decreased as the molar ratio of Mo to MoO3 increase. By XRD analysis only MoSi2 and $\alpha$-Al2O3 peaks were identified in the combusion products, In case of MoSi2 containing 20wt% Al2O3 5.1wt% Al existed into MoSi2 grains and 30.7wt% Si and 7.7wt% Mo existed into Al2O3 grains. The relative density of MoSi2 containing 10, 20, 30 and 40 wt% Al2O3 were 82.7, 85.2, and 81.9% respectively. The fracture strength of MoSi2-Al2O3 composites increased with increasing Al2O3 and that of MoSi2-20wt% Al2O3 composite was 195 MPa.