• Journal of Korea Foundry Society
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• v.20 no.1
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• pp.38-45
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• 2000

The remelting for recycling or thin aluminum scrap, such as aluminum chip generally involves melting of these pieces submerged in molten salt flux. In this study, the effects of salt flux compositions and alloying elements on the aluminum dropletscoalescence and oxide film removal were studied in 99.8%Al, Al-1.01%Cu, Al-1.03%Si, and Al-1.38%Mg alloys as a function of holding time at $740^{\circ}C$ Salt fluxes based on NaCl-KCl(1:1) with addition of 5wt.% fluorides(NaF, $Na_3AlF_6$, $CaF_2$) or 5 wt.% chloride($MgCl_2$, $AlCl_3$) were used. The experimental results show that NaCl-KCl(1:1) with addition of 5 wt.% fluorides exhibits better coalescence ability than that with chlorides. The oxide film is not removed by NaCl-KCl(1:1) with addition of 5 wt.%chlorides, while it is removed by NaCl-KCl(1:1) with addition of 5 wt.% fluorides. The aluminum droplets coalescence and oxide film removal by salt fluxes are related to interfacial tension tension between metal and salt flux.

• Proceedings of the KIEE Conference
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• 1999.07d
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• pp.1919-1921
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• 1999

AlN thin films were fabricated by sputter for the application of MIS device with Al/AlN/Si structure. We controled that sub-temperature room-temperature. Sputtering pressure 5 mTorr, flow ratio Ar:$N_2$=1:1(4sccm:4sccm), and appended hydrogen gas $0{\sim}5%$. AlN thin films thickness fabricated to maintain $2700{\AA}$ time control. Before the experiment remove to the contaminated material use the Ultrasonic every 10 minute use the acetone and ethanol, then use the HF remove oxide-substance at 10 second. To analyze characteristic of the $H_2$ gas addition period, C-V and I-V characteristic make and experiment $H_2$ gas at addition period progressive capability of I-V and C-V characteristic.

• Transactions of Materials Processing
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• v.8 no.3
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• pp.227-227
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• 1999

The effects of intermediate annealing (IA) and the final cold rolling (CR) condition on the microstructure and sagging resistance during brazing were investigated using three layer clad sheets composed of the Al-7.5 wt.%Si alloy (filler, thickness: 10 ㎛)/Al-1.3 wt.%Mn based alloy (core, 80㎛)/Al-7.5 wt.%Si alloy (filler, 10㎛). Also, the effect of 1.2∼2 wt.% Zn addition into the core on the sagging resistance of the clad sheets was determined. It was revealed that all the clad sheets fabricated by the optimum condition (IA at 690 K and CR to 20∼45%) show excellent sagging resistance with a limited erosion due to the formation of a coarsely recrystallized grain structure in the core during brazing. It was also revealed that the recrystallization behavior of the Al-1.3 wt.%Mn based alloy is hardly affected by the addition of 1.2-2 wt.%Zn during the brazing cycle. Therefore, the sagging resistance of the clad sheets is found to be governed not by the Zn content added in the A1-1.3wt.%Mn based core, but by the intermediate annealing and final cold rolling condition.

• Journal of the Korean Society for Heat Treatment
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• v.11 no.4
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• pp.274-282
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• 1998

The effect of Al addition on the fatigue properties of austenitic Fe-25Mn-Al-0.5C steels was studied. When Al was not added to the Fe-25Mn 0.5C steel, the strain induced ${\varepsilon}$ martensites, deformation twins and slip bands were formed during fatigue deformation. When 2wt% of Al was added to the steel, the deformation twins and slip bands were formed during fatigue deformation. When 5wt% of Al was added, only slip bands were formed. In low cycle fatigue test, the alloys containing 0wt% and 2wt%Al showed the cyclic hardening due to ${\varepsilon}$ martensites and deformation twins, resulting in shorter fatigue lives than the alloy containing 5wt%Al. In fatigue crack propagation test, the alloy without Al showed the highest crack propagation rate. The fracture surface of the alloy without Al was flat, whereas that of the alloy with 2% or 5%Al was rough. The ${\Delta}K_{th}$, values of the alloys with 0%, 2% and 5%Al were 16, 17.5, and $20.5MPam^{1/2}$, respectively.

• Journal of Welding and Joining
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• v.18 no.6
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• pp.102-107
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• 2000

It was attempted to improve the wear resistance of Al alloy under the load condition by making a formation of the thick surface hardening alloy layers. The thick surface hardening alloy layers were formed on 6061 Al alloys overlayed by MIG welding process with WC-12%Co powder addition. Effects of the dispersion of WE-12%Co powders on hardness and wear characteristics of alloys were investigated. The following results were obtained. Most of WE-12%Co powders are dispersed nearly uniform as unmelted particles in the matrix alloy. A part of WC-12%Co powders are melted in the molten pool, and during solidification {TEX}$Al_{9}Co_{2}${/TEX} appeared. With increasing addition of WC-12%Co powders, the hardness and specific wear resistance of the overlay weld alloys increased and reached Hv450 at WC-12%Co powder addition rate of 54g/min. It is considered that excellent wear resistance of the overlayed alloys was due to dispersed WC-12%Co powders and increased 10 times at WC-12%Co powder addition rate of 54 g/min than that of the WC-free overlaying layers.

• Korean Journal of Materials Research
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• v.32 no.10
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• pp.403-407
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• 2022

This research investigated the effect of Si addition on the microstructure, mechanical properties, electric and thermal conductivity of as-extruded Al 6013 alloys. As the content of Si increased, the area fraction of the second phase increased. As the Si content increased, the average grain size decreased remarkably, from 182 (no Si addition) to 142 (1.5Si), 78 (3.0Si) and 77 ㎛ (4.5Si) due to dynamic recrystallization by the dispersed second particles in the aluminum matrix during the hot extrusion. As the Si content increased, the yield strength and ultimate tensile strength increased. The maximum values of yield strength and ultimate tensile strength were 224 MPa and 103 MPa for the 6013-4.5Si alloy. As the amount of Si added increased, the electrical and thermal conductivity decreased. The electrical and thermal conductivity of the Al6013-4.5Si alloy were 44.0 % IACS and 165.0 W/mK, respectively. The addition of Si to Al 6013 alloy had a significant effect on its thermal conductivity and mechanical properties.

• Bulletin of the Korean Chemical Society
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• v.33 no.8
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• pp.2513-2516
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• 2012

This study examined the effects of the epoxidized castor oil (ECO) and $Al_2O_3$ content on the thermal stability and fracture toughness of the diglycidylether of bisphenol-A (DGEBA)/ECO/$Al_2O_3$ ternary composites using a range of techniques. The thermal stability of the composites was decreased by the addition of ECO and $Al_2O_3$ nanoparticles. The fracture toughness of the composites was improved significantly by the addition of ECO and $Al_2O_3$ nanoparticles. The composite containing 3 wt % $Al_2O_3$ nanoparticles showed the maximum flexural strength. Scanning electron microscopy (SEM) revealed tortuous cracks in the DGEBA/ECO/$Al_2O_3$ composites, which prevented deformation and crack propagation.

• Journal of the Korean Institute of Telematics and Electronics
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• v.27 no.6
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• pp.886-894
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• 1990

Sinterbility, microstructure, mechenical and electrical properties of yttriastabilized zirkconiz (92 mole % ZrO2 + 8 mole % Y2O3) doped with 0.5 mole % SiO2 and 0-2.O mole% Al2O3 were studied as a functin of Al2O3 addition. Sintered density increased with increasing Al2O3 addition up to o.5 mole%but decreased up to 1.0mole% Al2O3. Vickers hardness is proportional to sintered density. The specimen added 0.5mole% Al2O3 and 0.5mole% SiO2 exhibited a maximum conductivity. And the specimen added 0.5 mole % Al2O3 and 0.5 mole% SiO2 was measured a maximum electromotive force for a characteristics of oxyzen partial pressure.

• Journal of Korea Foundry Society
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• v.25 no.3
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• pp.128-133
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• 2005

The effects of Mn and Cr on the crystallization behaviors of Fe-bearing intennetallics in A356 alloy were studied. Coarse and acicular ${\beta}-Al_{5}$FeSi phase in A356-0.20wt.%Fe alloy was modified into small ${\alpha}$-Al(Fe,Mn)Si and ${\alpha}$-Al(Fe,Cr)Si phases in response to Mn and Cr addition, respectively. Increasing of Mn addition amount elevates the crystallizing temperature of ${\alpha}$-Al(Fe,Mn)Si and the Mn/Fe ratio in the ${\alpha}$-Al(Fe,Mn)Si. Cr is more effective to modify ${\beta}-Al_{5}$FeSi in comparison with Mn. ${\alpha}$-Al(Fe,Mn)Si phase had BCC/SC dual structure.

• Journal of the Korean Society for Heat Treatment
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• v.27 no.4
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• pp.185-190
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• 2014

The influences of small amount of Sn addition on microstructure and creep resistance of AZ91-0.4%Ca alloy have been investigated. The microstructure of the AZ91-0.4%Ca alloy was characterized by ${\alpha}$-(Mg) dendrite cells surrounded by eutectic ${\beta}(Mg_{17}Al_{12})$ and $Al_2Ca$ phases. The 0.5%Sn addition resulted in the formation of rod-shaped CaMgSn particles with the extinction of $Al_2Ca$. The Sn-containing alloy exhibited better creep resistance below $175^{\circ}C$, but the tendency was reversed above $200^{\circ}C$. The reason was discussed in relation to the change in thermal stability of ${\beta}$ phase in response to the Sn addition.