Historical Metallurgy DOIHistorical Metallurgy20165412937943 : Evolution of High Tin Bronze Technology in Korea as Observed in BronzeObjects of the Unified Silla Period, Excavated from the National GyongjuMuseum SiteJang Sik ParkJin Ok JooHongik UniversityKorea is famous for its long history of manufacturing high tin bronze objects of near peritectic composition by the application of forging and rapid cooling at approximately 700 C. Not much is known, however, of the origin and developmental processes of this technique. Fortunately, valuable evidence for assessing the associated technological evolution was found by examining the microstructure and chemistry of bronze objects excavated in the National Gyongju Museum construction site. Initial awareness of thetechnique was clearly visible in the selection of unleaded high tin bronze alloys of varying tin levels and the application of special thermo-mechanical treatments involving forging and quenching from the - or - phase field of the Cu-Sn system. This observation along with the excavation contexts suggests that the high tin technology was gradually established in Korea by a long period of experimentation, starting from the 8th century AD or earlier.Korea, high tin bronze, technological evolutionJ. S. Park and J. O. Joo, Korean J. Met. Mater. 54, 937 (2016).10.3365/KJMM.2016.54.12.937

Biomaterials & Nanomaterials DOIBiomaterials & Nanomaterials2015533220230 Mg-4Zn-0.5Ca Si, Mn, Sn Effect of Si, Mn, Sn on Tensile and Corrosion Properties of Mg-4Zn-0.5Ca Alloys for Biodegradable Implant MaterialsDae Hyun ChoJi Hoon Nam, Byeong Woo Lee, Ji Yong Park, Hyun Jung Shin, Ik Min ParkPusan National UniversityEffect of elements Si, Mn, Sn on tensile and corrosion properties of Mg-4Zn-0.5Ca alloys were investigated. The results of tensile properties show that the yield strength, ultimate tensile strength andelongation of Mg-4Zn-0.5Ca alloy increased significantly with the addition of 0.6 wt% Mn. This is considered the grain refinement effect due to addition of Mn. However addition of 0.6 wt% Si decreased yield strength, ultimate tensile strength and elongation. The bio-corrosion behavior of Mg-4Zn-0.5Ca-X alloys were investigatedusing immersion tests and potentiodynamic polarization test in Hank's solution. Immersion test showed that corrosion rate of Mg-4Zn-0.5Ca-0.6Mn alloy was the lowest rate and addition of 1.0 wt% Snaccelerated corrosion rate due to micro-galvanic effect in -Mg/CaMgSn phases interface. And corrosion potential (Ecorr) of Mg-4Zn-0.5Ca-0.6Mn alloy was the most noble among Mg-4Zn-0.5Ca-X alloys.biomaterials, casting, corrosion, scanning electron microscopy (SEM), magnesium alloyDae Hyun Cho, Ji Hoon Nam, Byeong Woo Lee, Ji Yong Park, Hyun Jung Shin, and Ik Min Park, Korean J. Met. Mater. 53, 220 (2015).10.3365/KJMM.2014.53.3.220Biomaterials & Nanomaterials20155311820826 Growth Mechanism of Multi-Layer Graphene at Low-Temperature by Plasma Enhanced Chemical Vapor DepositionKayoung YunDasol CheangJiyeon HyunAeran RohSun HeoLanxia ChengJiyoung KimPil-Ryung ChaJagab LeeHo-Seok NamKookmin University, University of Texas at DallasMulti-layer graphene is considered to be a potential replacement of copper wiring for LSI (large-scale integration). PECVD (plasma enhanced chemical vapor deposition) is one of the most reliablesynthesis techniques to manufacture high-quality, large-scale graphene at low temperature. Compared with thermal CVD graphene, the relatively lower quality of PECVD graphene is its main drawback. In order to suggest a solution for this problem, we studied the growth mechanism of multi-layer graphene deposited onto nickel by PECVD at 400 . We found that both segregation and solution-precipitation models affect the growth behavior of multi-layer graphene. To support this, we analyzed the influences of Ni-film thickness, cooling rate, and plasma energy on multi-layer graphene growth. The results from this study would be useful for optimizing graphene growth conditions for many applications.graphene, PECVD, growth mechanism, synthesis, nickel catalystKayoung Yun, Dasol CheangJiyeon HyunAeran RohSun HeoLanxia ChengJiyoung KimPil-Ryung ChaJagab LeeHo-Seok Nam, Korean J. Met. Mater. 53, 820 (2015).10.3365/KJMM.2015.53.11.820Biomaterials & Nanomaterials2016547526532Au Au-Pd Fabrication of Au-Pd Core-shell Nanoparticles using Au Thin-Film Dewetting at High Temperature and ChemicalSynthesis MethodsMin-Gyu KimHye-Jung Lee, and Yong-Jun OhHanbat National Univ.Au-Pd bimetallic nanoparticles (NPs) have received a lot of attention in the fields of catalysts and hydrogen sensors. In this study, Au-Pd core-shell NP arrays were successfully fabricated using two steps:formation of the ordered array of Au NPs cores via solid-state dewetting of a Au thin film on a topographic silica substrate, and Pd shell formation via chemical synthesis using two different surfactants (CTAB and CTAC). Using the CTAB surfactant in particular, a 2-D composite structure comprised of an ordered array of Au-Pd NPs, with smaller Pd NPs on the nanoscopic gaps between the Au-Pd NPs, could be formed. This structure is expected to have potential application in resistance-base hydrogen sensors.nanostructured materials, chemical synthesis, surface, X-ray diffraction, gas sensorsM.-G. Kim, H.-J. Lee, and Y.-J. Oh, Korean J. Met. Mater. 54, 526 (2016).10.3365/KJMM.2016.54.7.526Biomaterials & Nanomaterials20165412925930Ti-39Nb-6Zr Effect of Aging Time and Temperature on Microstructure and Mechanical Properties of Ti-39Nb-6Zr AlloyHyun Jun KwonKa Ram Lim, Yong Tae Lee, Dong Geun Lee,Jun Hee Lee, and Seung Eon KimKorea Institute of Materials ScienceThe aim of this study is to optimize the microstructure and mechanical properties of Ti-39Nb-6Zr (TNZ40) for bio-implant applications. TNZ40 was designed to have a low elastic modulus (~40 GPa) and good biocompatibility. However, the alloy shows relatively low strength compared to other titanium alloys for bio-implant. In the present study, we tried to obtain the proper combination of elastic modulus andstrength by tailoring the direct aging conditions after severe plastic deformation. The mechanical properties are closely linked to characteristics including the distribution and volume fraction of precipitates.implant, titanium alloy, low elastic modulus, direct aging, microstructure, mechanicalpropertiesH. J. Kwon, K. R. Lim, Y. T. Lee, D. G. Lee, J. H. Lee, and S .E. Kim, Korean J. Met. Mater. 54, 925 (2016).10.3365/KJMM.2016.54.12.925

Casting&Solidification&Heat ... DOICasting/Solidification/Heat Treatment20155314350Nb-Si-B Nb+T2 Microstructure of the Nb-Si-B Alloys in the Nb+T2 RegionSoo-Hyun ChooYoung Do Kim, Sung-Tag Oh, Seong Lee, Sung-Soo Ryu,Myung-Jin SukKangwon National University, Hanyang University, Seoul National University of Science and Technology, Agency for Defence Development, Korea Institute of Ceramic Engineering and TechnologyIntermetallic-based materials are interesting for high temperature structural applications because of their good mechanical properties and enhanced oxidation resistance. In this study microstructuralexamination of the Nb-Si-B alloys at Nb-rich compositions was performed. The Nb-rich corner of the Nb-Si-B system is very attractive because the constituent phases are Nb (a ductile and tough phase with a high melting temperature) and T2 (a very hard intermetallic compound with favorable oxidation resistance), which make a good combination for high temperature structural materials. At compositions lower than 82 at%Nb the microstructure shows the T2 primary phase and eutectic (T2+Nb), while the Nb primary phase and eutectic were formed at higher compositions. Hardness tests (Rockwell A-scale and micro Vickers) were carried out to estimate the optimal composition for good mechanical properties.intermetallics, solidification, microstructure, hardness test, T2 phaseSoo-Hyun Choo, Young Do Kim, Sung-Tag Oh, Seong Lee, Sung-Soo Ryu,and Myung-Jin Suk, Korean J. Met. Mater. 53, 43 (2015).10.3365/KJMM.2014.53.1.43Casting/Solidification/Heat Treatment2015534277286 CZ Design of insulators in a Czochralski silicon furnace by numerical analysisJong-Sik ShinWang-Ki Choi, Ki-Young KimKorea University of Technology and Education, Hana MaterialsThe effect of insulators in a Czochralski furnace on the power consumption and the oxygen content in the melts as well as in the Si ingots was investigated with no radiation shield by using a commercial software, Femag-Cz. Location and thickness of the insulator were changed. The calculated results with no radiation shield were compared to those with radiation shield. The top insulator showed better results than the top-side and bottom insulators for the power consumption and Si melt temperature in the calculations of separately installed insulators. The oxygen content in the melt decreased with increasing the thickness of insulators for the top and top-side insulators. Installation of insulators at the three locations at the same time, the power consumption and the oxygen content in the melt and the Si ingot were improved comparedto those of separately installed insulators.semiconductors, crystal growth, solidification, computer simulation, czochralskiJong-Sik Shin, Wang-Ki Choi, and Ki-Young Kim, Korean J. Met. Mater. 53, 277 (2015).10.3365/KJMM.2014.53.4.277Casting & Solidification & Heat Treatment2015535352358CaO-SiO2-Al2O3 Ca Al A study on the Solubility of Ca and Al in CaO-SiO2-Al2O3 slag systemDong Jun MinEun Jin Jung, Sang Hoon Lee, Wan Ho KimYonsei University, Research Institute of Industrial Science and Technology, PoscoThermodynamic study for CaO-SiO2-Al2O3 slag system was carried out to understand the refining ability of Ca and Al in ferrosilicon. The effect of slag composition and oxygen partial pressure on refining ability of slag was also thermodynamically evaluated. Experimental results indicated that equilibrium concentration of Ca and Al are both decreased with increasing SiO2 activity of slag and oxygen partial pressure. Also, the effect of activity coefficients of Ca and Al in molten alloy was not significant while activities of each component in slag were important determining factors. Refining ability of Ca and Al of CaO-SiO2-Al2O3 slag from ferrosilicon is possibly increased by controlling interfacial oxygen partial pressure and activities of components of slags.ferrosilicon, metals, purification, thermodynamics propertiesDong Jun Min, Eun Jin Jung, Sang Hoon Lee, Wan Ho Kim, Korean J. Met. Mater. 53, 352 (2015).10.3365/KJMM.2015.53.5.352Casting/Solidification/Heat Treatment2015539627636 Al-Zn A Study on Development of High Strength Al-Zn Based alloy for Die Casting Kyoung-Mook Lim, Ik-Min ParkSang-Soo Shin, Gil-Young Yeom, Hyun-Jin SonPusan National University, Korea Institute of Industrial Technology, Oh-Sung Co. LtdIn this study, the microstructural evolution and various characteristics of Al-20~45wt%Zn alloyswere investigated. In terms of microstructure, as the amount of Zn addition to the alloys increased, the-phase size decreased and the + non-equilibrium solidification phase fraction increased. Also, increasingZn content improved the wear resistance of the alloys, but reduced the damping capacity and toughness ofthe alloys. Their physical properties of the Al-Zn alloy with high Zn content, specifically the wear resistanceand toughness, were superior to those of commercial ALDC12 alloys for die-casting. Based on these results,we considered the possibility of application of the developed Al-Zn alloy as a structural material.alloys, casting, mechanical properties, hardness test, impact testKyoung-Mook Lim, Ik-Min Park, Sang-Soo Shin, Gil-Young Yeom, Hyun-Jin Son, Korean J. Met. Mater. 53, 627 (2015).10.3365/KJMM.2015.53.9.627Casting & Solidification & Heat Treatment2016543194203SKD61 SKH51 Effects of Powder Feeding Rate on the Crack Formation in Laser-Surface Alloying-Hardened SKD61 Hot Die Steel using SKH51 PowderSeong-Won ChoiKwang-Hyeon Lee, Jeong Suh, Myeong-Hwan Oh and Chung-Yun KangPusan National University, Korea Institute of Machinery & MaterialsA laser surface-melting alloying process using a laser beam is a new surface-hardening process of obtaining an alloying layer that melts the surfaces of substrates and alloying powder at the same time. Thisstudy used SKD61 hot die steel as a substrate and SKH51 powder as an alloying powder. The laser beam speed and the laser power were fixed at 70 mm/sec and 2 kW. The power feeding rate was changed from 0 rpm to 6 rpm (step: 1 rpm). The alloying layer showed high hardness (710~830 Hv), but cracks occur at a high powder feeding rate. Cracks occur at more than 5 rpm, and the lengths of cracks become longer as the powder feeding rate increases. Moreover, cracks were observed at the dendrite boundary, and dendrite protrusions were observed on the fracture surfaces. As the powder feeding rate increases, the concentration of the Mo, V, and W in alloying layer increase. The liquidus and solidus temperatures decreased by as muchas 6 and 26 . As a result of calculating the aspect ratio (penetration depth/width) of the molten zone, it was found that there is no difference as the powder feeding rate increases. Therefore, strain by solidification contraction was constant with an increase in the powder feeding rate, but cracks occur, and the number of cracks increases because the solidus temperature decreases and the ductility of alloying layer reduces.surface modification, melting, optical microscopy, laser surface alloying hardeningS.-W. Choi, K.-H. Lee, J. Suh, M.-H. Oh and C.-Y. Kang, Korean J. Met. Mater. 54, 194 (2016).10.3365/KJMM.2016.54.3.194Casting & Solidification & Heat Treatment2016544261269 Effect of Convection on the Isothermal Coupled Peritectic Solidification in the Single Crystal SuperalloyJiho GuChanghoon Sung, Jongho Shin, Seongmoon Seo and Jehyun LeeChangwon National University, Doosan Heavy Industries & Construction Co. Ltd, Korea Institute of Materials ScienceThe / two-phase growth commonly observed at interdendritic regions in Ni-base superalloys is known to be the eutectic microstructure. However, it is still unclear whether this is due to a eutectic or peritectic reaction. Directional solidification experiments of the Ni-base superalloy CMSX-10 were performed at low solidification rates in order to induce the coupled growth of / phases and to investigate their growth behavior. The and phases were found to grow simultaneously, maintaining an isothermal interface. Directional solidification experiments in a thin tube (0.8 mm ID) suggest that convection enhances the formation of two phase peritectic growth with a planar interface and the / might be the couped peritectic.alloy, solidification, microstructure, scanning electron microscopy (SEM), eutecticJ.H. Gu, C.H. Sung, J.H. Shin, S.M. Seo, and J.H. Lee, Korean J. Met. Mater, 54. 261 (2016).10.3365/KJMM.2016.54.4.261Casting/Solidification/Heat Treatment2016548585591 625 Microstructure and Mechanical Properties of Inconel 625 Alloy on Low Carbon Steel by Heat Treatment after Overlay WeldingSeungpil KimJaeho Jang, Jungsoo Kim, Byung Jun Kim, Keun Yong Sohn, and Dae-Geun NamKorea Institute of Industrial Technology, Inje UniversityOverlay welding technique is one of methods used to improve metal mechanical properties such as strength, toughness and corrosion resistance. Generally, Inconel 625 alloy is used for overlay weldinglayer on low carbon steels for economic consideration. However, the method produces some problems in the microstructure of the cast structure and some defects, caused by the elevated temperatures of the overlay welding process. To resolve these problems, heat treatments are required. In this study, Inconel 625 alloy was welded on a low carbon steel by the overlay welding process to investigate the resulting microstructure and mechanical properties. A double heat treatment was performed to improve the mechanical properties of the welding and substrate layers. It was found that Inconel 625 alloy had an austenite microstructure after the first heat treatment, but the low carbon steel had a ferrite-pearlite microstructure after the secondheat treatment. After the double heat treatment, the sample showed the optimum hardness because of grain refinement and homogenization of the microstructure.metals, welding, microstructure, hardness test, double heat treatmentS. Kim, J. Jang, J. Kim, B. J. Kim, K. Y. Sohn and D.-G. Nam, Korean J. Met. Mater. 54, 585 (2016).10.3365/KJMM.2016.54.8.585Casting/Solidification/Heat Treatment20165496596711Cr-1.25Mo-0.25V Solidification Segregation and Homogenization Behavior of 1Cr-1.25Mo-0.25V Steel IngotDong-Bae KimYoung-Sang Na, Seong-Moon Seo, and Je-Hyun LeeDae-gu Mechatronics & Materials Institute, Korea Institute of Materials Science, Changwon National UniversityAs a first step to optimizing the homogenization heat treatment following high temperature upset forging, the solidification segregation and the homogenization behaviors of solute elements werequantitatively analyzed for 1Cr-1.25Mo-0.25V steel ingot by electron probe micro-analysis (EPMA). The random sampling approach, which was designed to generate continuous compositional profiles of each solute element, was employed to clarify the segregation and homogenization behaviors. In addition, ingot castings of lab-scale and a 16-ton-sized 1Cr-1.25Mo-0.25V steel were simulated using the finite element method in three dimensions to understand the size effect of the ingot on the microsegregation and its reduction during the homogenization heat treatment. It was found that the microsegregation in a large-sized ingot was significantly reduced by the promotion of solid state diffusion due to the extremely low cooling rate. On the other hand, from the homogenization point of view, increasing the ingot size causes a dramatic increase in the dendrite arm spacing, and hence the homogenization of microsegregation in a large-sized ingot appears to be practically difficult.1Cr-1.25Mo-0.25V steel, solidification segregation, homogenization, secondary dendrite armspacing, residual segregation indexD.-B. Kim, Y.-S. Na, S.-M. Seo, and J.-H. Lee, Korean J. Met. Mater. 54, 659 (2016).10.3365/KJMM.2016.54.9.659Casting/Solidification/Heat Treatment2016549672680 STD61 Study on the Surface Microstructure of a Modified STD61 Steel Mold Used for the Die Casting ProcessHa-Young YuSeung-Joon Lee, Minwoo Kang, Suk-Jin Lee, Won Jon Yang, Jae Suk Jeong,Byung-Hoon Kim, and Young-Kook LeeYonsei University, Hyundai Motor Company, Korea Institute of Materials Science, Doosan Heavy Industries & ConstructionThe surface microstructure and crack formation of an aluminum die-casting mold were investigated. The mold was made of a modified STD61 steel, and was used for more than 165,000 cycles. Themold surface consisted of four layers; an oxidized layer, a decarburized layer, a network carbide layer and a tempered martensite matrix. The depth down to the hardest network carbide layer was ~200 m. Insidethe matrix, M3C transition carbides were dissolved so that solute C joined pre-existing M23C6 and MC carbides to make them coarse. About 60% of thermal fatigue cracks had a depth less than 200 m due to the hard network carbide layer, which obstructed the propagation of cracks. Cracks of over 200 m were filled with oxide wedges of Al and Si which was which flown from the molten alloy as well as the Fe oxide.alloys, casting, microstructure, scanning electron microscopy (SEM), thermal fatigue crackH.-Y. Yu, S.-J. Lee, M. Kang, S.-J. Lee, W. J. Yang, J. S. Jeong,B.-H. Kim, and Y.-K. Lee, Korean J. Met. Mater. 54, 672 (2016).10.3365/KJMM.2016.54.9.672Casting/Solidification/Heat Treatment20165411838845CM247LC Evolution of the Solidification Microstructures in Directionally Solidified CM247LC RodJeongseok LeeSeokhwan Kown, Byunggwan Yoon, Byungmoon Chang, Yongil Jung, and Jehyun LeeChangwon National University, Korea Lost-Wax Co.Directional solidification of CM247LC was performed at a constant growth velocity (300 mm/h) using a Bridgman type furnace. Microstructural features, including the number of grains, PDAS, and EBSD IPF map, were investigated with progressive positions from the starter block. As directional solidification proceeded, the number of grains decreased and PDAS increased. These results indicate that the thermal gradient decreases with distance from the starter block. Thermal gradient changes were estimated by dendrite spacing change in the directionally solidified rod. The EBSD IPF map showed that almost all of the grains were close to the preferred direction, but with heights of about 300 mm from the starter block, some grains at the center of the specimen exhibited quite different crystallographic directions near the gate instead of the preferred direction.Ni base superalloy, solidification, electron backscattering diffraction(EBSD)J. Lee, S. Kwon, B. Yoon, B. Chang, Y. Jung, and J. Lee, Korean J. Met. Mater. 54, 838 (2016).10.3365/KJMM.2016.54.11.838Casting/Solidification/Heat Treatment2017552132138Alloy 738 4 mm Numerical and Experimental Analysis on the Cavity Formation and Shrinkagefor Investment Cast Alloy 738 4 mm-Thick Rectangular TubeMyeong-Il ParkKyeong-Min Kim, Yeong-Chul Lee, Jung-Seok Lee, Jae-Hyun Lee,Jae-Hyun Yoo, Sang-Hu Park, and Yoon Suk ChoiSchool of Materials Science and Engineering, Pusan National UniversityInvestment casting for the thin (4 mm thick) rectangular tube (40 mm wide, 80 mm high and 200 mm long) was carried out numerically and experimentally for Alloy 738, which is a precipitation-hardenedNi-base superalloy. Two types of rectangular tubes, one with a regular array (10 mm by 10 mm square array) of protruded rods (3 mm in diameter and 3mm in height) embedded on the outer surface and the other with just smooth surface, were investment-cast at the same time through the side feeding mold design. The investment casting simulation predicted the presence of cavities, particularly in the area away from the gate for both types of rectangular tubes. In particular, for the rectangular tube with embedded protruded rods cavities were found mainly in the areas between the protruded rods. This simulation result was qualitatively consistent with the experimental observation from the X-ray analysis. Also, both prediction and experiment showed that the dimensional shrinkage (particularly in the longitudinal direction) of the investment-cast rectangular tube is reduced by having protruded rods embedded on the outer surface. Additional numerical attempts were made to check how the amount of cavities and dimensional shrinkage change by varying the preheating temperature and the thickness of the mold. The results predicted that theamount of cavities and the dimensional shrinkage are significantly reduced by increasing the preheating temperature of the mold by 200 . However, an increase in mold thickness from 10 mm to 12 mm showed almost no difference in cavity population and a slight decrease in dimensional shrinkage.Alloy 738, Ni-base superalloy, investment casting, shrinkage, cavity, simulationM.-I. Park, K.-M. Kim, Y.-C. Lee, J.-S. Lee, J.-H. Lee, J.-H. Yoo, S.-H. Park, and Y. S. Choi, Korean J. Met. Mater. 55, 132 (2017).10.3365/KJMM.2017.55.2.132

Composite Materials DOIComposite Materials20155317581TiC Nb Effect of Nb Addition on the Deformation Behavior of TiC Matrix Solid Solution at High TemperatureSoon-Gi ShinKangwon National UniversityIn order to clarify the effect of Nb addition on the deformation properties of a sintered TiC matrix solid solution at high temperature, we made a study using a compression test at temperatures from 983 to 2223 K and at the strain rates from 2.1104 to 5.2102/s. Further, X-ray photoelectron spectroscopic (XPS) measurements were carried out. We found that solid solution hardening in the Nb added TiC matrix was smaller than that in a Mo added TiC matrix solid solution, though the size misfit parameter in the Nb added TiC matrix was larger than that in Mo added TiC matrix, which had an extremely high strength, being 15 to 20 times higher than TiC. The work softening phenomenon was for the first time clearly observed in the present investigation. This phenomenon shows the presence of a frictional resistance to dislocation motion. The deformation equation of state at the yield stress can be expressed by p=A (y/G)mexp (Q/RT) where m=9 and Q=112 kJ/mol in the low temperature range at and below 1083 K and where m=10 and Q=343 kJ/ mol in the high temperature range at and above 1873 K. The XPS measurement suggests that dislocationsolution atom interaction resulting from a change in electronic structure should be effective for solution hardening.composites, sintering, mechanical properties, compression test, solid solutionSoon-Gi Shin, Korean J. Met. Mater. 53, 75 (2015).10.3365/KJMM.2014.53.1.75Composite Materials2015532145150 LED ZnO-Bi2O3-P2O5 A Study of Optical Properties of a Glass Composition of a ZnO-Bi2O3-P2O5 Glass/Phosphor Composite for a White LEDIl-Gu KimYoung-Seok Kim, Jong-Hwan Kim, Jae-Yeop Jung, Su-Yeon Choi, Hyun-Jun Park, Bong-Ki RyuPusan National UniversityFor implement the white light-emitting diode (LED) package, glass-phosphor composite was produced with different glass composition and glass/phosphor ratio. To maximize the LED light emission characteristic, the glass frit was required a low firing temperature and high refractive index. We selected the bismuth phosphate glass due to their low melting and high refractive index. With further addition of Bi2O3, the value of Tg ,Ts was decrease and coefficient of thermal expansion, refractive index were increased,due to the Bi2O3 acts as modifier in the glass increasing the non-bridging oxygens. The refractive index changes of the glass frit affect the optical property of the composite. With higher contents of Bi2O3 glass composition, the transmittance and emission intensity of the composite was increased. These results suggest that the difference in refractive index between the phosphor and glass frit is minimized, the loss of light is minimized.composites, sintering, optical properties, thermal analysis, white LEDIl-Gu Kim, Young-Seok Kim, Jong-Hwan Kim, Jae-Yeop Jung, Su-Yeon Choi, Hyun-Jun Park, and Bong-Ki Ryu, Korean J. Met. Mater. 53, 145 (2015).10.3365/KJMM.2015.53.2.145Composite Materials20155312911918 AlN/Cu AlN Fabrication of AlN/Cu Composites Using Electroless Plating and Evaluationof Their Thermal Properties according to AlN Particle SizeSung Chul ChoSe-Hyun Ko, Hye Sung Kim, Jae-Pyung Ahn, Jun Hyun HanChungnam National University, Korea Institute of Industrial Technology, Pusan National University,Korea Institute of Science & TechnologyAlN/Cu composite powders with a core-shell structure were synthesized by a new technique using electroless plating of Cu on AlN particles and consolidated by spark plasma sintering (SPS). Dependence of the thermal conductivity and coefficient of thermal expansion (CTE) of the AlN/Cu composites on the particle size of AlN were studied. The thermal conductivity and coefficient of thermal expansion were significantly dependent on the existence of both boundary pores surrounding the Cu-coated AlN particles and the internal pores of the AlN particles. In order to eliminate the pores, the temperature and pressure of SPS were increased and the AlN particles were heat-treated at high temperature. Adoption of the core-shell AlN/Cu composite powders facilitated the fabrication of AlN/Cu composites with low porosity and uniform distribution in the AlN in Cu matrix.composites, powder processing, thermal conductivity, coefficient of thermal expansion (CTE),scanning electron microscopy (SEM)Sung Chul Cho, Se-Hyun Ko, Hye Sung Kim, Jae-Pyung Ahn, Jun Hyun Han, Korean J. Met. Mater. 53, 911 (2015).10.3365/KJMM.2015.53.12.911Composite Materials2016542138144 Cu Estimation of the Infiltration Potential of Cu-Alloy for Core BitsKi Ho KimWoo Young YoonEHWA Diamond Ind. Co. Ltd, Korea UniversityTo estimate the infiltration potential in metal binders, a new parameter, the EII (Effective Infiltration Index), which can be determined with the surface tension and viscosity data of each liquid metal used in the binder, is introduced. The parameter was found to be closely related to the measured infiltration distance. As an infiltrant for core bits, the Cu-Sn alloy with a higher EII value was selected and compared with the conventional Cu-Zn alloy. For the formation of harder rock, a finer W size in the matrix is generally used to maintain the cutting rate. However, in such a case, the infiltration potential becomes lower and a fully infiltrated microstructure cannot be obtained. In this study, the matrix with the Cu-Sn alloy showed an evenly infiltrated and sound microstructure up to a W size of 1 m and had a longer tool life than the conventional Cu-Zn alloy in a simulated drilling test.composites, infiltration, thermodynamic properties, hardness test, core bitK. H. Kim and W. Y. Yoon, Korean J. Met. Mater. 54, 138 (2016).10.3365/KJMM.2016.54.2.138Composite Materials2016544288294Hydrogenation Behaviors of MgHx-Graphene Composites by Reactive Mechanical GrindingHydrogenation Behaviors of MgHx-Graphene Composites by Reactive Mechanical GrindingMin-hyuk JangSo-Hyun Park and Tae-Whan HongKorea National University of TransportationIn order to mitigate the disadvantage of the Mg hydrides, several studies have been conducted that have used MgHx intermixed with carbon. Graphene is a kind of carbon allotrope that is easily subject to a desorption reaction at low temperatures because such a reaction is exothermic. In this work, an MgHx-graphene mixture has been prepared by reactive mechanical grinding. The synthesized powder was characterized by X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and simultaneous thermogravimetric (TG) and differential scanning calorimetric (DSC) analyses. The hydrogenation behaviors were evaluated using a Sieverts type automatic pressure-composition-temperature (PCT) apparatus without activation treatment. From the characteristics of the absorption kinetics and the curves observed, the role of graphene as a catalyst in hydrogen absorption was determined. According to the results of the PCI curve, the available hydrogen storage amounts for MgHx-5 wt% graphene composites had maximum values of 3.69, 5.09, and 5.72 wt% at 423, 523, and 623 K, respectively. Those values for MgHx-10 wt% graphene were 5.08, 5.45, and 5.83 wt% at 423, 523, and 673K, respectivelyhydrogen absorbing materials, mechanical alloying/milling, hydrogen, X-ray diffraction, MgHx-graphene compositesM.-H. Jang, S.-H. Park, and T.-W. Hong, Korean J. Met. Mater. 54, 288 (2016).10.3365/KJMM.2016.54.4.288Composite Materials2016545364369 SiCTi3SiC2 Effect of Pressurizing during Compaction and Sintering on the Formationof Reaction-Bonded SiCTi3SiC2Sun-Han KimYang-Il Jung, Young-Woo Rhee, Dong-Jun Park, Jung-Hwan Park, Jeong-Yong Park, Hyun-Gil Kim and Yang-Hyun KooKAERIA reaction-bonded SiC-Ti3SiC2 ceramic composite was produced for use in a ceramic-metal composite cladding tube. The diffusion reaction between TiC and Si was investigated with respect to process pressure. The mole-fraction of TiC and Si was controlled to be 3:2 to obtain a Ti3SiC2 phase in the ceramic composite. Sintering was conducted at 1450 C where TiC particles could react with melted Si. SiC ceramic composites consisting of Ti3SiC2 and TiSi2 matrix phases were obtained. The formation of the constituent phases was strongly related to the processing pressure. The number of second phases in the SiC-Ti3SiC2 composite was controlled by adjusting the processing pressure. When the powder compacts were not pressurized, no Ti3SiC2 phase was formed. However, the Ti3SiC2 phase was formed under pressurizing during compaction and/or sintering. The higher the pressure the higher the purity of SiC-Ti3SiC2. The dual-phased SiC-Ti3SiC2 composite, however, revealed the decreased resistance to high-temperature oxidation. It is suggested that the incorporation of TiSi2 in the composite increases the oxidation resistance as well as mechanical property.ceramics, sintering, microstructure, X-ray diffraction, oxidation resistanceS.-H. Kim, Y.-I. Jung, Y.-W. Rhee, D.-J. Park, J.-H. Park, J.-Y. Park, H.-G. Kim and Y.-H. Koo, Korean J. Met. Mater. 54. 364 (2016).10.3365/KJMM.2016.54.5.364Composite Materials2016549688697 Ni Al-Ni Effect of Added Ni on the Deposition State of Kinetic Sprayed Al-Ni CompositeJaeick KimSeungtae Lee and Changhee LeeKinetic Spray Coating Laboratory (NRL), Division of Materials Science and Engineering, Hanyang UniversityThe liners of shaped charges, a type of weapon, should possess good penetration ability and explosive power. Conventionally this is achieved by fabricating reactive Al-Ni composite layers on the Cu liners, which by themselves have fine penetration ability but poor explosive power. However, there are no studies related to the deposition behavior and interfacial state of a mixed Al-Ni composite applied by kinetic spraying, despite its importance in terms of the effect on reactivity. Thus, this study investigated pure Al and mixed Al-Ni composites that were deposited by kinetic spray process and the effect of Ni on the deposition and interfacial bonding state. The deposition efficiency was degraded by addition of Ni, but the density and bond strength were enhanced with the increase in Ni fraction. The primary cause of the lowered deposition efficiency was insufficient particle velocity, with the intense effect of strain hardening of Ni. However, the tamping effect induced by harder Ni particles contributed to a reduction in pores, and improvement of the interfacial bonding state.Al-Ni composite, kinetic spray process, deposition behavior, interfacial stateJ. Kim, S. Lee, and C. Lee, Korean J. Met. Mater. 54, 688 (2016).10.3365/KJMM.2016.54.9.688

Corrosion & Surface Treatment DOICorrosion & Surface Treatment20155312027 316L End Grain Attack Failure Analysis of End Grain Attack and Pit Corrosion in 316L StainlessSteel PipeUn Bong Baek,Byung Hak Choe, Jin Hee Lee, Jong Hun Shim, Eui Soo Kim, Sung Hoon NamKorea Research Institute of Standards and Science, Gangneung-Wonju National University, National Forensic ServiceThe aim of this paper was to analyze the cause of surface cracks and pit corrosion on 316L pipe. An End Grain Attack (EGA) as a kind of pit mechanism was conducted on the pipe surface. The early stage of the EGA may come from under-deposit of caustic-water formation compositions like Na+, K+, Ca+, and Mg+ etc. The under-deposit corrosion is caused by the corrosion layer on the pipe surface followed by crevice corrosion due to accumulation of Cl or S composition between the corrosion layer and the pipe surface. In the early stage, the EGA occurred in all grain boundaries beneath the under-deposit corrosion. In the later stage of EGA, almost all the early attacked grain boundaries stopped at a limited depth of about 10 m. Meanwhile, only the smallest number of the attacked boundaries progressed into the pipe as pit corrosion and resulted in leak failure.316L pipe, pit corrosion, under-deposit, end grain attackUn Bong Baek, Byung Hak Choe, Jin Hee Lee, Jong Hun Shim, Eui Soo Kim, and Sung Hoon Nam, Korean J. Met. Mater. 53, 20 (2015).10.3365/KJMM.2014.53.1.20Corrosion & Surface Treatment2015532104109 Microstructure of Carbon Film Deposited Using Hot-Filament Chemical Vapor DepositionDo-Hyun KwonJong-Keuk Park, Wook-Seong Lee, Young-Joon BaikElectronic Materials Research CenterThe microstructure of carbon film, deposited using hot-filament chemical vapor deposition, was investigated in relation to deposition pressure and methane concentration as deposition variables. Methane concentration in hydrogen gas was varied from 0.5 to 5% in volume. Deposition pressures were 5, 15, 45 and75 Torr. Filament temperature and deposition temperature were fixed at 2100 and 950 , respectively. With increasing methane concentration, the surface morphology changed its microstructure from microcry- stalline diamond, to nanocrystalline diamond, to graphite. Raman spectroscopic analysis and X-ray diffraction analysis confirmed the bonding structures corresponding to each microstructure. At 5 Torr, the surface showed a fine grained morphology, different from the microstructures in the other pressure cases; however, the bonding nature also changed from diamond to graphite with increasing methane concentration.carbon and graphite, deposition, microstructure, SEM, diamondDo-Hyun Kwon, Jong-Keuk Park, Wook-Seong Lee, and Young-Joon Baik, Korean J. Met. Mater. 53, 104 (2015).10.3365/KJMM.2014.53.2.104Corrosion & Surface Treatment2015532110115 Tunable Structural Design and Thermal Characteristics of SiO2 Hybrid on Cu2O Pigment via Dual-Effect of NH4OH CatalystRi YuJiYeon Yun, Heeseung Yang, Jae-Hwan Pee, YooJin KimKorea Institute of Ceramic Engineering & TechnologyThis paper reports the tunable structural design and thermal characteristics of a SiO2 layer onCu2O pigment via a dual-effect of NH4OH catalyst. We prepared octahedron Cu2O 200~300 nm in size andsuccessfully synthesized a core-shell Cu2O@SiO2 structure using a modified Stober method in which theNH4OH concentration was adjusted. The NH4OH solution dipping time was controlled such that the Cu2Ocore was generated with a yolk-shell and a hollow-shell. The silica-coated Cu2O raw materials were calcinedat various temperatures (150~500 ). The thermal and color effects of the silica on the Cu2O were charact-erized by scanning electron microscopy, CIE L*a*b* color parameter measurements, transmission electronmicroscopy, and X-ray diffraction.Cu2O, nanostructured materials, surface modification, phase transformation, transmission electronmicroscopy (TEM)Ri Yu, JiYeon Yun, Heeseung Yang, Jae-Hwan Pee, and YooJin Kim, Korean J. Met. Mater. 53, 110 (2015).10.3365/KJMM.2014.53.2.110Corrosion & Surface Treatment2015532116122SiO2 ZrO2 Microstructure Changes of Aluminum Titanate Refractory Doped SiO2 and ZrO2 in Molten SteelDami KimHyung-Tae Kim, Sung-Soo Ryu, Hyeong-Jun KimKorea Institute of Ceramic Engineering and TechnologyAluminum titanate (AT) ceramics has high potential as alloy casting refractory materials due totheir good thermal shock resistance which results from their low coefficient of thermal expansion. In aprevious study, AT doped SiO2 and ZrO2 were developed to achieve stability and mechanical strength athigh temperature. In this work, the changes of microstructure of AT doped SiO2 and ZrO2 were investigatedin molten steel. A finger rotating test of sintered AT was carried out at 1300 for 30 min, 1 h, 2 h, and 3h. Even if there was no reaction between AT and molten steel, a new surface was formed, followed by thedecomposition of AT by the heat from molten steel, which was dominantly constituted of Al and Si due todecomposition of AT and Mullite phases. Some of the new surface layer was found to have been eroded byfluctuations of the molten steel.aluminum titanate, high-temperature corrosion, low thermal expansion, high-temperaturestrengthDami Kim, Hyung-Tae Kim, Sung-Soo Ryu, and Hyeong-Jun Kim, Korean J. Met. Mater. 53, 116 (2015).10.3365/KJMM.2014.53.2.116Corrosion & Surface Treatment2015534231236 PEMFC Pt/C Performance and Durability of Pt/C Catalyst for PEMFC Modified byE-beam IrradiationWon Jun JoHyein Hwang, Mincheol Choi, Dongwook Lim, Sang Eun Shim,Sung-Hyeon Baeck,Byung Cheol LeeInha UniversityThe influence of electron beam irradiation on the catalytic activity of Pt/C for polymer electrolytemembrane fuel cell (PEMFC) was investigated using a 2.5 MeV electron beam. Pt catalysts supported onVulcan XC-72R were synthesized by a polyol method using chloroplatinic acid hydrate (H2PtCl66H2O) as aPt precursor. Before and after e-beam irradiation, all synthesized catalysts were characterized by variousphysical and electrochemical techniques. Crystallinity change before and after e-beam irradiation wasinvestigated by X-ray diffraction (XRD). Transmission electron microscopy (TEM) was utilized to examinethe particle size of Pt. Pt loading amounts were determined by thermal gravimetric analysis (TGA). Thecatalytic activity for PEMFC was measured by both a half cell test and full cell test. The results show thatthe proper e-beam irradiation significantly improved the electrochemical activity of Pt/C.PEMFC, Pt/C catalyst, e-beam, electrodeWon Jun Jo, Hyein Hwang, Mincheol Choi, Dongwook Lim, Sang Eun Shim, Sung-Hyeon Baeck, and Byung Cheol Lee, Korean J. Met. Mater. 53, 231 (2015).10.3365/KJMM.2014.53.4.231Corrosion & Surface Treatment2015534237243 CeO2-Na2O-SiO2 Hydrophobicity behavior in the crystalized CeO2-Na2O-SiO2 glassHyun-Joon ParkYoung-Seok Kim, Jong-Hwan Kim, Il-Gu Kim, Jae-Yeop Jung, Su-Yeon Choi,Bong-Ki RyuPusan National UniversityMetal atoms in rare-earth oxides (REOs) have a different electronic structure, where the unfilled 4f orbitals are shielded from interactions with the surrounding environment by the full octet of electrons in the 5s 2p 6 outer shell. Thus, these metal atoms would have a lower tendency to exchange electrons and form a hydrogen bond with interfacial water molecules. In this study, we have prepared (10+x)CeO2-30Na2O-(60-x)SiO2 (in mol%, x=0,5,10) glass system and examined the characterization of hydrophobicity behavior of crystallized Na2O-SiO2 glass containing CeO2. In addition, we confirmed the change in the wettability of the glass surface due to change the heat treatment time for crystallization and a change amount of CeO2. It was found that the contact angles of crystallized specimens (CNS glasses) got higher by about 40~50 by the addition of CeO2 and 0~18 hr-heating, compared with the specimens without CeO2 and 0~8 hr heat treatment.In order to explain the hydrophobicity behavior of CNS glasses, surface structure through FT-IR ATR ranging from 3000 cm1 to 4000 cm1 was examined. The band characteristic of -OH bridges at about 3200 cm1, 3400 cm1 and 3600 cm1 are attributed to the existence of hydrogen bond. At 3700 cm1, as the intensity ofpeaks (0.006~0.036) gets higher, the contact angles increase by 51 to 73glasses, crystal growth, wetting, scanning electron microscopy (SEM), CeO2Hyun-Joon Park, Young-Seok Kim, Jong-Hwan Kim, Il-Gu Kim, Jae-Yeop Jung, Su-Yeon Choi, and Bong-Ki Ryu, Korean J. Met. Mater. 53, 237 (2015).10.3365/KJMM.2014.53.4.237Corrosion & Surface Treatment2015536389397 Evaluation of Failure Probability and Remaining Gas-Pipe Lifetime usingStatistics with Hypothetical Pit DataByung Hak ChoeSeong Jun Kim, Jong Heon Shim, Woo Sik Kim, Chul Man KimGangneung-Wonju National University, Korea Gas Corporation (KOGAS)Corrosion data obtained from in-line inspection can be applied to assess present integrity as well as to predict future integrity of gas pipelines. This can be accomplished by using a combination ofprobabilistic analyses and simulation. With a deterministic method, failure models (e.g., NG 18 or ASMEB31G)can only provide Safe or Fail criteria for corroded pipelines. However, a probabilistic method can offer Probability of Failure (POF) using the same models. This paper is focused on determining the POF for hypothetical corrosion-pit data of a gas pipeline. The study presented a ten-step procedure for obtaining the POF of a gas pipeline using three statistical methods (i.e., Monte Carlo, FOSM: First-Order Second-Moment, and FORM: First-Order Reliability Method). Furthermore, the coefficient of variance, regarding the value of POF sensitivity in relation to data variation, was mostly affected by the corrosion-depth parameter of the pit data.gas pipeline, corrosion data, probability of failure, statistical method, Monte Carlo, FOSM, FORMByung Hak Choe, Seong Jun Kim, Jong Heon Shim, Woo Sik Kim, Chul Man Kim, Korean. J. Met. Mater. 53, 389(2015)10.3365/KJMM.2015.53.6.389Corrosion & Surface Treatment2015536398405 QT ( ) Plasma Nitrocarburizing Techiques with Quenchingand Tempering for Manufacture of Vehicle PartsInsup LeeDongeui UniversityPlasma nitrocarburizing (PNC) treatment of quenching and tempering (QT)-treated SNCM220steel samples was carried out at 570 for 5 hours in plasma-nitriding equipment. The PNC in a gas mixtureof N2:H2:CH4 (85:13.75:1.25 by vol%) produced a compound layer composed mainly of -Fe2-3(N,C)-phase onthe surface of SNCM220 steel. The thickness of the compound layer decreased with increasing CH4 contentwhen N2 composition was fixed to 85%. The amount of -Fe2-3 (N,C)-phase in the compound layer increased with increasing CH4 gas content up to 1.25 vol%. When there was more than 1.5% CH4 in the gas mixture, the cementite phase started to form, which reduced the thickness of the compound layer. The gas carbo nitriding (GCN) treatment was performed at 860 for 2 hours followed by oil quenching at 130 and tempering at 180 for 2 hours. The GCN treatment produced a hardened layer with a martensite structurecontaining high carbon content (0.6 wt%). The effective case-depth (550 HV0.3) was about 300 m. Compared with the GCN, the PNC and QT-treated SNCM220 steel had a higher surface- hardness (by 150-200 HV0.1), but lower near-surface hardness and bulk hardness (by 300-400 HV0.1). However, PNC treatment of QTtreatedSNCM220 steel showed better wear resistance. This was due to a smaller worn-wear-track section and a lower friction-coefficient, compared with the result from GCN treatment. Therefore, in the very near future, it is expected that gas carbo nitriding treatment could be replaced by the combined QT+Plasma nitrocarburizing process for manufacturing vehicle parts.plasma nitrocarburizing, metals, surface modification, wear, hardness testInsup Lee, Korean J. Met. Mater. 53, 397 (2015).10.3365/KJMM.2015.53.6.398Corrosion & Surface Treatment2015536406411Corrosion of Fe-Al Alloys at 600 and 700 in a Gas Mixture of H2O, H2S, N2Corrosion of Fe-Al Alloys at 600 and 700 in a Gas Mixture of H2O, H2S, N2Dong Bok LeeMin Jung KimSungkyunkwan UniversityFe-(4.8, 9.2, and 14.3 wt%)Al alloy were significantly corroded at 600 and 700 for up to 60 h in a mixed gas consisting of 0.031 atm of H2O, 0.0044 atm of H2S, and balance of N2. The Fe-4.8Al alloy corroded rapidly, forming outer FeS scales and inner (FeS, Fe2AlO4)-mixed scales. These were formed because the sulfidation of Fe to form FeS in the outer scales facilitated the oxidation of Al to Fe2AlO4 in the inner scales. The Fe-(9.2, 14.3)Al alloys formed much thinner scales, which consisted primarily of outer FeS scales and inner Al2O3 scales that effectively provided corrosion resistance.metals, casting, oxidation, scanning electron microscopy, H2S corrosion, H2O corrosionDong Bok Lee, Min Jung Kim, Korean. J. Met. Mater. 53, 405(2015)10.3365/KJMM.2015.53.6.406Corrosion & Surface Treatment2015537464473F53 The Localized Corrosion Behavior Associated with Microstructureof F53 Super Duplex Stainless SteelSoon-Tae KimIn-Sung Lee, Kyeong-Ho Kong, Yong-Soo Park, Jong-Hoon Lee,and Won-Jon YangYonsei University, Korea Institute of Materials ScienceThe localized corrosion behavior associated with microstructure of F53 super duplex stainlesssteel (SDSS) was investigated using a potentiodynamic polarization test, a critical crevice temperature test,an electron probe micro-analyzer analysis, and scanning electron microscopy-energy dispersivespectroscopy analyses. Crevice corrosion was initiated at the / phase boundaries, MOx inclusions (whereM is Cr, Mn, Al, Fe, or Ti), as well as Cr and Mo depleted areas adjacent to the -phases precipitated in theF53 SDSS alloy. This alloy had been annealed at 1050 followed by improper water-cooling, and thecorrosion was propagated into the -phases because the pitting resistance equivalent number (PREN) of the-phase was smaller than that of the -phase. As cooling rate increased, the variation of the -phasesdecreased, and the content of the Cr and Mo rich -phases decreased, thereby increasing the corrosionresistance.alloys, annealing, corrosion resistance, scanning electron microscopy, microstructureSoon-Tae Kim, In-Sung Lee, Kyeong-Ho Kong, Yong-Soo Park, Jong-Hoon Lee, and Won-Jon Yang, Korean J. Met. Mater. 53, 464 (2015).10.3365/KJMM.2015.53.7.464Corrosion & Surface Treatment2015538535540Na2WO4 Effect of Na2WO4 in electrolyte on mechanical properties of oxide layer on Al alloy via plasma electrolytic oxidationYoung Gun Ko, Dong Hyuk ShinHae Woong Yang, Yeon Sung Kim, Joo Hyun Park, Gye Won KimYeungnam University, Hanyang UniversityThis paper investigates with the mechanical properties of Al alloy samples coated by plasma electrolytic oxidation (PEO) using a phosphate electrolyte with a Na2WO4 solution. Under an A Ccondition of 60Hz, PEO coatings were applied for 300 seconds at a current density of 100mA/cm2. Microstructural observations of the PEO-coated samples revealed that the size and fraction of the micro-pores remained nearly constant while WO3 and W were additionally in corporated in the oxide layer using the Na2WO4 solution. During PEO coating, the Na2WO4 solution dissociated into Na+ and WO4 2- and the high dielectric voltage exceeding the ignition voltage activated the electrochemical reactions of WO42- in the anode, leading to the formation of WO3 and W. The incorporation of WO3 and W is expected to lead to enhancement of the hardness and wear resistance of the PEO-coated Al sample.Al alloy, coating, plasma electrolytic oxidation, mechanical properties, scanning electronmicroscopy(SEM)Hae Woong Yang, Yeon Sung Kim, Joo Hyun Park, Gye Won Kim, Young Gun Ko, and Dong Hyuk Shin. Korean J. Met. Mater. 53, 535 (2015).10.3365/KJMM.2015.53.8.535Corrosion & Surface Treatment2015538541548 Silicon carbide thin film deposited by unbalanced magnetron sputtering methodYoung-Joon BaikKyung-Eun Bae, Ki-Woong Chae, Jong-Keuk Park, Wook-Seong LeeKorea Institute of Science and Technology, University of Science and Technology, Hoseo UniversityThe effect of sputter target power and substrate bias voltage on the deposition of silicon carbide thin film was investigated. Films were deposited using unbalanced magnetron sputtering method with sintered silicon carbide target connected to a direct current electric power from 50 to 200 W. Ar gas was used as a sputtering gas. The distance between the target and the substrate was 7.5 cm and the deposition pressure was 3 m Torr. We used a Si single crystal wafer as a substrate, which was heated at 450. The substrate bias voltage was varied between 0 and -100V. Deposited films consisted of columnar grains with several nm width, which formed a texture whose orientation was influenced by the bias voltage. Most of thegrains were crystalline which was confirmed by transmission electron microscopy. The hardness measured by a nano-indentation method showed a super-hardness of about 50 GPa.thin films, sputtering, microstructure, transmission electron microscopy(TEM)Young-Joon Baik, Kyung-Eun Bae, Ki-Woong Chae, Jong-Keuk Park, Wook-Seong Lee, Korean J. Met. Mater. 53, 541 (2015).10.3365/KJMM.2015.53.8.541Corrosion & Surface Treatment2015538549554 CrZrSiN Effect of the substrate bias voltage on the mechanical properties of nanocomposite CrZrSiN thin filmsSang-Yul LeeKyu-Sung Kim, Hoe-Kun Kim, Joung-Hyun La, Kwang-Bae KimKorea Aerospace UniversityNanocomposite CrZrSiN thin films were deposited with various substrate bias voltages from 0 to-200 V using unbalanced magnetron sputtering. The crystalline structure, microhardness, microstructure,and adhesion properties of the CrZrSiN thin films were evaluated by X-ray diffraction, Fischer scope,field-emission scanning electron microscopy, and a scratch tester. The surface roughness and depositionrate decreased with an increase in the substrate bias voltage. The substrate bias voltage increased and thehardness increased to 36 GPa at -100 V, then decreased to 32 GPa as the substrate bias voltage furtherincreased to -200V. The CrZrSiN thin films maintained their hardness up to 800 while the hardness ofCrZrN film decreased rapidly over 500. The critical load (Lc3) increased from 8 N to 35 N up to a substratebias voltage of -100 V, while the critical load decreased to 8 N with further increase of the substrate biasvoltage.thin films, plasma deposition, mechanical properties, transmission electron microscopy(TEM)Sang-Yul Lee, Kyu-Sung Kim, Hoe-Kun Kim, Joung-Hyun La, Kwang-Bae Kim, Korean J. Met. Mater. 53, 549 (2015).10.3365/KJMM.2015.53.8.549Corrosion & Surface Treatment2015539618626 DLC Effect of Reduction in Lateral Friction Coefficient due to Stable DLC Coating onDicing Performance and Durability of Diamond Micro-BladesSong-Hee KimJaecheol JangKangwon National UniversityA DLC coating was deposited onto diamond micro-blades with Cu/Sn bond metal doped with WS2and MoS2 as a solid lubricant to enhance the cutting efficiency. In comparison with blades without the DLCcoating, the blades with the DLC coating showed a decreased specific wear rate in a ball-on-disc wear testand less momentary energy consumption in a dicing test. This is ascribed to reduction of the lateral frictioncoefficient with the work piece. A qualitative analysis of the reduction of momentary energy consumptionwas carried out to evaluate the effect of DLC coating on dicing performance. Chipping sizes of the dicedworkpiece surfaces were reduced by the DLC coating, which is beneficial for accurate machining.DLC coating, dicing efficiency, diamond micro-blades, friction coefficient, momentary energyconsumptionSong-Hee Kim, Jaecheol Jang, Korean J. Met. Mater. 53, 618 (2015).10.3365/KJMM.2015.53.9.618Corrosion & Surface Treatment20155310711720 Haynes230 Kinetics for Aluminum Coatings and Degradation Properties of Aluminide - Coated and pre-oxidized Haynes230 Alloys via Pack Cementation RouteMin Seok KimJin Soo Park, Young Il Son, Joon Sik ParkHanbat National Unversit, Republic of Korea 23D Printing Department, INSTECH, Republic of Korea 3Agency for Defense SystemSA 508 Gr.3 Mn-Mo-Ni low alloy steel forgings thicker than 200 mm are used for reactor pressure vessels in nuclear power plants. The cooling rate difference along the thickness direction during thequenching process causes variation in the microstructure and mechanical properties. The microstructural variation and its influence on the fracture toughness of RPV steels were investigated in this study. Thecleavage fracture toughness in the transition region were evaluated with the ASTM E1921 master curve method for samples at different locations from the inner surface to the center thickness of the RPV steel.The microstructural features, such as the area fraction, and the size and distribution of precipitates were quantitatively evaluated at each sampling position. Microstructure observations showed that at near thesurface position, bainite laths are finer, and furthermore, the carbides are smaller and homogeneously distributed. The fracture toughness at the surface was better than those at deeper positions. The referencetemperature T0 showed a linear relationship with the area fraction of the carbides bigger than a certain critical size. It is concluded that the size of the precipitates caused by the cooling rate gradient may have adominant role in controlling the cleavage fracture toughness variation along the thickness direction for a very thick RPV steel.low alloy steels, forging, fracture toughness, mechanical properties, SA508 Gr.3Min Seok Kim,Jin Soo Park, Young Il Son, Joon Sik Park, Korean J. Met. Mater. 53, 711 (2015).10.3365/KJMM.2015.53.10.711Corrosion & Surface Treatment20155311761769 304 Crevice Corrosion Evaluation of 304 Stainless Steel Pipe Joint for Potable Water System with Chloride Ion ConcentrationSun-Ah ParkJin-Ho Kim, Jung-Gu Kim, Yeong-Ho KimSungkyunkwan University, POSCO Technical Research LabThe crevice-corrosion behavior of 304 stainless steel at several chloride concentrations was investigated with two types of specimens: plate and pipe joint. There is a good correlation of crevicecorrosion behavior between the plate specimen and pipe joint specimen. The crevice-corrosion of both specimens initiated when the chloride ion concentration exceeded 200 ppm. Four stages of crevice-corrosion were observed: isolated pits, coalescing pits, crystallographic attack, and polishing attack. Consequently,the critical chloride ion concentration of crevice-corrosion is affected by the intrinsic property of the material.metals, joining, corrosion, image analysis, potable waterSun-Ah Park, Jin-Ho Kim, Jung-Gu Kim, Yeong-Ho Kim, Korean J. Met. Mater. 53, 761 (2015).10.3365/KJMM.2015.53.11.761Corrosion & Surface Treatment20155311770777Alloy 600 Effects of hydrogen charging and electrotransport treatment on the anodic polarization behavior and mechanical property of Alloy 600Jin-Seok ParkYong-Sang Kim, Tae-Heum Nam, Jung-Gu KimSungkyunkwan UniversityElectrotransport treatment is a new method to remove the hydrogen from inside metals. Potentiodynamic polarization tests, electrochemical impedance spectroscopy (EIS), and tensile tests wereused to investigate the effect of electrotransport treatment on the anodic behavior and hydrogen embrittlement characteristics of Alloy 600. The hydrogen-charged specimen exhibited a higher anodiccurrent than that of the uncharged specimen. In particular, the anodic current was reduced so that the electrotransport treatment had features similar to that of the uncharged specimen. The EIS results showed that the capacitance loop of the hydrogen-charged specimen was smaller than that of the electrotransport treatment specimen. Results regarding tensile behavior revealed that electrotransport treatment enhanced the mechanical property of hydrogen-charged specimens.metals, deformation, hydrogen, tensile test, electrotransport treatmentJin-Seok Park,Yong-Sang Kim, Tae-Heum Nam, Jung-Gu Kim, Korean J. Met. Mater. 53, 770 (2015).10.3365/KJMM.2015.53.11.770Corrosion & Surface Treatment20155312859866 Mn TWIP Oxidation of High Mn TWIP Steels in Reheating Furnace ConditionsDong Bok LeePoonam YadavSungkyunkwan UniversityHigh Mn TWIP steels were oxidized at 1150-1250 for up to 2h in 85%N2-10%CO2-5%O2 gas to determine their oxidation behavior in the reheating furnace. They oxidized fast to form thick, nonadherent oxide scales and the internal oxidation zone. The oxide scales consisted primarily of FeO, Fe2O3, MnO, MnAl2O4, and FeMn2O4, indicating that Mn, Fe, and Al were the dominant oxidizing species. They grew primarily through the outward diffusion of cations. Internal oxides formed intra- and inter-granularly through the inward diffusion of oxygen ions. They consisted of oxides of Mn, Fe, Al, Si, Cr and Cr.metals, casting, oxidation, scanning electron microscopy (SEM), high Mn TWIP steelDong Bok Lee, Poonam Yadav, Korean J. Met. Mater. 53, 859 (2015).10.3365/KJMM.2015.53.12.859Corrosion & Surface Treatment20155312867872 Effect of Atmospheric Plasma Treatment on Interlayer Formation and Adhesion Strength between Substrate and Coating LayerDong-Yong KimHong-Seok Park, Kwang-Jin Bae, Jong-Gu Kim, and Young-Rae ChoPusan National UniversityThe effect of atmospheric plasma treatment on change in the interlayer and the adhesion strength between the substrate and the coating layer was investigated. Soda-lime glass and indium-tin oxide (ITO) coated glass plates were used as the substrate, and the surface energy was calculated from the wetting angle of liquids on the substrates. To study the effect of surface treatment on the adhesion strength between the substrate and the coating layer, chrome (Cr) thin film was deposited on the surface treated substrates by sputtering. For the analysis of the interlayer, auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS) were used. The surface energy of the substrates increased as a function of exposure time for atmospheric plasma surface treatment. When the exposure time exceeded 20 sec, the surface energy increased to a saturated value of 76 mJ/m2. The adhesion strength between the substrate and Cr coatinglayer according to the surface treatment showed a similar trend of the surface energy. The atmospheric plasma surface treatment using argon and oxygen gases promoted the formation of an interlayer that wasidentified as chrome oxide (Cr2O3). The thicker chrome-oxide interlayer contributed to the increase in adhesion strength between the substrates and the Cr coating layer.thin films, surface modification, interfaces, auger electron spectroscopy, adhesion strengthDong-Yong Kim, Hong-Seok Park, Kwang-Jin Bae, Jong-Gu Kim, and Young-Rae Cho, Korean J. Met. Mater. 53, 867 (2015).10.3365/KJMM.2015.53.12.867Corrosion & Surface Treatment201654117Study of the effect of Pyrophosphate in low voltage Plasma Electrolytic Oxidation on the corrosion resistance of AZ31B Magnesium alloyStudy of the effect of Pyrophosphate in low voltage Plasma Electrolytic Oxidation on the corrosion resistance of AZ31B Magnesium alloyJae Gon YunEng Chan Kim and Ki Hong KimYeungnam University, Catholic University of DaeguIn this study, low voltage Plasma Electrolytic Oxidation (PEO) was utilized to eliminate the drawbacks of high voltage PEO such as high cost, dimensional deformation, and porosity. Low voltage PEO produces a thin coating, which leads to low corrosion resistance. In order to solve this problem, 0.1~0.6 M pyrophosphates were added to a bath containing 1.4 M NaOH and 0.35 M Na2SiO3.PEO at 70Vwas conducted at 25 for 3 minutes. The chemical composition, morphology, and corrosion resistance of the anodized coating were analyzed. The anodized film was composed of MgO, Mg2SiO4, and Mg2O7P2. Themorphology of the film showed a inappropriately dense structure and low porosity in the anodized layers. It is found that low voltage Plasma Electroly tic Oxidation in cooperation with phosphating treatment can provide good corrosion protection for the AZ31B magnesium alloy.magnesium, AZ31B, plasma electrolytic oxidation, pyrophosphate, low voltageJae Gon Yun, Eng Chan Kim and Ki Hong Kim, Korean J. Met. Mater. 54, 01 (2016).10.3365/KJMM.2016.54.1.01Corrosion & Surface Treatment2016541814Oxidation behavior of amorphous boron carbide film deposited using the unbalanced magnetron sputtering methodOxidation behavior of amorphous boron carbide film deposited using the unbalanced magnetron sputtering methodKyung Eun BaeJong-Keuk Park, Wook-Seong Lee and Young Joon BaikKorea Institute of Science and TechnologyThe oxidation behavior of amorphous boron carbide thin film, deposited using the unbalanced magnetron sputtering method, was investigated. Weight change was measured using thermo gravity analysis under the condition of dry flowing air (100 mL/min), with increasing temperature of up to 1200 as well as at constant temperature. For the isothermal oxidation experiment, dry Ar gas was used until the oxidation temperature was stabilized; then, the Ar gas was replaced with dry air. The weight gain was negligibly small under 600 and then increased rapidly with increasing temperature. The isothermal oxidation curves show decreasing weight gain rate with oxidation time. At 1000 , the weight gain was shown to become negative after a certain period. This isothermal weight change behavior can be ascribed to diffusional oxidation and weight loss due to the evaporation of liquid boron oxide. The possibility of the transition of boron oxide to boric acid at room temperature under an ambient atmosphere was also discussed.thin films, sputtering, oxidation, raman spectroscopy, thermal gravimetric analysis.Kyung Eun Bae, Jong-Keuk Park, Wook-Seong Lee and Young Joon Baik, Korean J. Met. Mater. 54, 08 (2016).10.3365/KJMM.2016.54.1.08Corrosion & Surface Treatment20165411521 Al2O3 Effect of Microstructural Features on Optical Transmittance Mechanism in Vacuum Kinetic Sprayed Al2O3 FilmJinyoung KimHyungkwon Park, Jin-su Nam, Kyung Soo Son, Young Tae Im, Jae Wook Lee, Bong Geun Chung and Changhee LeeHanyang University, LG Electronics, Sogang UniversityGlass materials have been applied in various industrial fields. Research on improvement of mechanical properties has consistently been performed due to this materials intrinsically vulnerable characteristics. Surface modification is considered as the promising method to supplement the weakness; especially, ceramics are thought of as appropriate materials for film materials because of their outstanding mechanical properties and their chemical stability. However, unfortunately, the optical transmittance of ceramic materials is poor, and can rather restrict this materials utilization in glass. In this regard, the optical transmittance mechanism of vacuum kinetic sprayed Al2O3 film was investigated. To control and analyze the films optical property, the gas flow rate, as a main process variable, was controlled; then, post heat-treatment was performed. Consequently, the films optical property was determined by threemicrostructural factors. That is, crystallite size, defects (including lattice distortion), and amorphous phase, generated during particle deposition, were found to strongly affect the transmittance.glass, coating, optical property, UV-vis spectrometer, vacuum kinetic sprayJinyoung Kim, Hyungkwon Park, Jin-su Nam, Kyung Soo Son, Young Tae Im, Jae Wook Lee, Bong Geun Chung and Changhee Lee, Korean J. Met. Mater. 54, 15 (2016).10.3365/KJMM.2016.54.1.15Corrosion & Surface Treatment20165426878 (Cr, Mn) Effects of Alloying Elements (Cr, Mn) on Corrosion Properties of Carbon Steel in Synthetic SeawaterYoungmin HyunHeesan KimHongik UniversityEffects of alloying elements, manganese and chromium, on corrosion resistance of carbon steel were examined using weight loss test and electrochemical tests (polarization test and electrochemicalimpedance spectroscopy (EIS)) in synthetic seawater at 60 . The results from the weight loss test showed that chromium effectively improved corrosion resistance of carbon steel during the entire immersion time, but manganese improved corrosion resistance after the lowered corrosion resistance at the beginnings of immersion. Unlike the weight loss test, the electrochemical tests showed that the corrosion resistance did not increase with immersion time, in all the specimens. This disagreement is explained by the presence of rust involved in electrochemical reaction during electrochemical tests. The analysis of rust with transmission electron microscopy (TEM)energy dispersive spectroscopy (EDS) showed that theamorphous-like rust layer located at the metal/rust interface with enriched alloying element (Cr, Mn) prevents diffusion of corrosive species into a metal/rust interface effectively, which leads to increasedcorrosion resistance. The initial corrosion behaviour is also affected by the rust types. In other words, manganese accelerated the formation of spinel oxides, negatively affecting corrosion resistance.Meanwhile, chromium accelerated the formation of goethite but impeded the formation of spinel oxides, positively affecting the corrosion resistance. From the above results, the corrosion resistance of steel is closely related with a rust type.alloys, annealing, corrosion, transmission electron microscopy (TEM), X-ray diffractionY. M. Hyun and H. S. Kim, Korean J. Met. Mater. 54, 68 (2016).10.3365/KJMM.2016.54.2.68Corrosion & Surface Treatment2016544237245 Cu Effects of Plating Conditions on Thickness and Surface Roughness of Electroless-Plated Cu DepositsKee Hwan LeeSang Jin Park and Jun Hyun HanChungnam National UniversityCopper thin films were coated on polyethylene terephthalate(PET) substrates by electroless plating. The effects of the ultra-sonication, the initial roughness of the PET substrates, and the plating time on the thickness and roughness of the electroless-plated Cu deposits were studied. The thickness and roughness of the Cu deposits were measured by scanning electron microscopy(SEM) observations and a surface profiler. In the early stage of Cu plating, the ultra-sonication and high initial roughness of the PET substrates promoted an increase in the thickness of the Cu deposits, but they suppressed the increase in thickness of the Cu deposits when plated for a long time. The surface roughness of the Cu deposits plated on PET with a very low initial roughness increased with plating time due to the agglomeration of Cu atoms. However, the surface roughness of the Cu deposits on the PET with a high initial roughness decreased with increasing plating time, since the deep valleys of the rough PET surface were filled with Cu atoms preferentially.thin films, plating, surface, ultrasonics, roughnessK. H. Lee, S. J. Park, and J. H. Han, Korean J. Met. Mater. 54, 237 (2016).10.3365/KJMM.2016.54.4.237Corrosion & Surface Treatment2016545304312Effect of Propargyl Alcohol on Ni-Diamond Composite Electrodeposition forEnhancing Cutting PerformanceEffect of Propargyl Alcohol on Ni-Diamond Composite Electrodeposition forEnhancing Cutting PerformanceSanghyuk LeeDonghyun Kim, Kyungsik Son, Yongje Choi, Wonsub ChungPusan National University, Hyosung Corporation, Korea Institute of Industrial TechnologyA typical brightener-propargyl alcohol-was added to enhance the cutting performance during Ni-diamond composite electrodeposition. Electrochemical analysis was performed and mechanical properties such as hardness and wear resistance were examined. In addition, the surface morphology of composite coating layers was observed using an optical microscope, and using image analysis software, thedispersivity of the diamond particles was analyzed to calculate the number of single diamond particles. A galvanostatic test was employed to identify the electrodeposition mechanism as a function of the concentration of propargyl alcohol. When 0.1 mg/ of propargyl alcohol was added, the dispersivity and adhesion performances of the Ni-diamond coating layer were optimized for cutting tools.composites, deposition, wear, image analysis, diamondS. Lee, D. Kim, K. Son, Y. Choi, and W. Chung, Korean J. Met. Mater. 54, 304 (2016).10.3365/KJMM.2016.54.5.304Corrosion & Surface Treatment2016545313321 Mg-4Al-2Sn-xCa Corrosion behavior of die-cast Mg-4Al-2Sn-xCa alloyKyung Chul ParkDae Hyun Cho, Byeong Ho Kim, Kyung Ro Kim, Ik Min ParDefence Agency for Technology and Quality, Pusan National UniversityIn the present work, the effect of Ca additions on microstructure and corrosion characteristics of high pressure die-cast Mg-4Al-2Sn alloy has been investigated. Mg-4Al-2Sn-xCa (x= 0, 0.3 and 0.7wt.%)alloy was prepared by using a high pressure die-casting method. Results indicated that the microstructure of Mg-4Al-2Sn alloy consisted of -Mg, Mg17Al12 and Mg2Sn phase. With increase of Ca additions, CaMgSn phase was newly formed and grain size was sharply decreased. From the test results, the corrosionresistance of die-cast Mg-4Al-2Sn alloy was significantly improved by Ca addition. It is considered that stabilization of Mg(OH)2 layer and refinements of microstructure with increase of Ca additions.metals, casting, corrosion, scanning electron microscopy (SEM)K. C. Park, D. H. Cho, B. H. Kim, K. R. Kim, and I. M. Park, Korean J. Met. Mater. 54, 313 (2016).10.3365/KJMM.2016.54.5.313Corrosion & Surface Treatment2016546390399CaO Effect of CaO Addition on the High-Temperature Oxidation of Mg AlloysSoon Yong ParkShae Kwang Kim and Dong Bok LeeSungkyunkwan University, Korea Institute of Industrial TechnologyCaO-added Mg alloys were cast in air, hot extruded to thin plates, and oxidized in air at high temperatures. During the casting process, the CaO was decomposed into Ca in the -Mg matrix and formed Al2Ca precipitates along grain boundaries. A thin, nonuniform CaO-rich layer was formed on the surface during the casting and oxidation. Based on this study, the oxidation mechanism of the CaO-added Mg alloys during casting and oxidation is proposed.alloy, casting, oxidation, thermal analysis, magnesiumS. Y. Park, S. K. Kim, and D. B. Lee, Korean J. Met. Mater. 54, 390 (2016).10.3365/KJMM.2016.54.6.390Corrosion & Surface Treatment2016547492502 Cu, Sb 409L Comparison of Corrosion Behavior of Low-Alloy Steel Containing Copper and Antimony with 409L StainlessSteel for a Flue Gas Desulfurization SystemSun-Ah ParkSu-Bin Shin, and Jung-Gu KimSungkyunkwan UniversityThe corrosion behavior of low alloy steel containing Cu, Sb and 409L stainless steel was investigated for application in the low-temperature section of a flue gas desulfurization (FGD) system. The electrochemical properties were evaluated by potentiodynamic polarization testing and electrochemical impedance spectroscopy (EIS) in 16.9 vol% H2SO4 + 0.35 vol% HCl at 60 . The inclusions in these steels were identified by electron probe microanalyzer (EPMA). The corrosion products of the steels were analyzed using scanning electron microscope (SEM) with energy dispersive spectroscopy (EDS) and transmission electron microscopy (TEM). The corrosion rate of the low alloy steel containing Cu, Sb was about 100 times lower than that of 409L stainless steel. For stainless steel without passivation, active corrosion behavior was shown. In contrast, in the low alloy steel, the Cu, Sb compounds accumulated on the surface improved the corrosion resistance by suppressing the anodic dissolution reaction.low alloy steel, copper, precipitation, corrosion, flue gas desulfurization (FGD) systemS.-A. Park, S.-B. Shin, and J.-G. Kim, Korean J. Met. Mater. 54, 492 (2016).10.3365/KJMM.2016.54.7.492Corrosion & Surface Treatment2016548552558 Fabrication of Decorative Coating/Patterning of Ceramic Pigment Powder Using Vacuum Kinetic Spraying ProcessHyungkwon ParkJinyoung Kim, Hansol Kwon, Seongtae Lee, and Changhee LeeHanyang UniversityVacuum kinetic spraying (VKS) is a relatively advanced process, by which a dense film can be fabricated at room temperature. Various materials including ceramic, metal, polymer and composite can beused as the substrate and coating materials. In this research, red and blue color films were successfully fabricated on glass substrates using Co(Al, Cr)2O4 and C9H13CdN2O4SSe ceramic pigment powders in a VKS system. Although the deposition behavior of each powder differed according to particle size and/or materials, it was confirmed that the brightness and transmittance of the color film could be easily changed by controlling the process parameters. Furthermore, using masking technology, design color patterns were fabricated. As a result, it is cautiously expected that the VKS process can be utilized to produce decorative coating/patterning for product design.vacuum kinetic spray (aerosol deposition), decorative coating, optical property, ceramics,patterning systemH. Park, J. Kim. H. Kwon, S. Lee, and C. Lee, Korean J. Met. Mater. 54, 552 (2016).10.3365/KJMM.2016.54.8.552Corrosion & Surface Treatment2016549645651High Temperature Oxidation Behavior of Mg-5% Ca-1% Zn AlloysKwon Yong JiDong Bok LeeSungkyunkwan UniversityPure Mg, Mg-5wt%Ca, and Mg-5wt%Ca-1wt%Zn alloys were cast, and their high-temperature oxidation behavior was investigated to determine the roles of Ca and Zn in oxidation. Ca and Zn additions refined the microstructure by formation of Mg2Ca and Ca2Mg6Zn3, respectively, at grain boundaries. Ca increased the oxidation resistance by forming a thin, compact CaO scale on the surface. However, Zn decreased the oxidation resistance because of the formation of Ca2Mg6Zn3, which increased the MgO-forming tendency.alloys, casting, oxidation, scanning electron microscopy (SEM), Mg-Ca-Zn alloysK. Y. Ji and D. B. Lee, Korean J. Met. Mater. 54, 645 (2016).10.3365/KJMM.2016.54.9.645Corrosion & Surface Treatment2016549652658 Effect of Potassium Persulfate on Current Efficiency for Gold PlatingInjoon SonHo-Sang Sohn, and Kyung Tae KimKyungpook National University, Korea Institute of Materials ScienceIn this study, the effect of potassium persulfate on current efficiency for gold plating was investigated using electrochemical techniques. The current efficiency in the low-current-density range greatly decreased when potassium persulfate was added to the gold plating solution. However, the current efficiency in the high-current-density range did not change with the addition of potassium persulfate. The measured contact resistances of the resulting gold-plated layers showed almost similar values, regardless of the addition of potassium persulfate, suggesting that potassium persulfate does not affect the property of the gold layers. Linear sweep voltammetry and partial polarization curves showed that the persulfate ion was reduced when the noble potential was more than that of the gold ion. Therefore, the current efficiency for gold plating decreased when potassium persulfate was added in the low-current-density range becauseat such a current-density the reduction of persulfate preferentially occurs.electroplating, gold plating, current efficiency, potassium persulfate, connectorI. Son, H.-S. Sohn, and K. T. Kim, Korean J. Met. Mater. 54, 652 (2016).10.3365/KJMM.2016.54.9.652Corrosion & Surface Treatment20165410723731 Mg Effect of Added Magneisum on the Coating Properties of Galvanized Steel SheetsMoon-Hi HongDeok-Gu Kang, Doo-Jin Paik, Hyeon-Seok Hwang, and Sung-ho ParkPOSCO Steel Production DivisionThe effect of a small amount of added Mg on the microstructure, Fe-Al inhibition layer, corrosion resistance and welding properties of hot-dip galvanized and galvannealed steel sheets were investigated.Both the microstructure and distribution of Mg were measured by scanning electron microscopy, transmission electron microscopy, glow discharge spectrometer and electron probe micro analyzer. A thinMg layer was inhomogeneously precipitated between the Zn-coating and Al inhibition layer. During the annealing process around 470-510 , the Mg layer was completely diffused into the inside and/or extreme surface of the Zn coating. The corrosion resistance of galvannealed steel sheets produced in a commercial galvanizing line was significantly improved by adding a small amount of Mg into the molten zinc pot. Fe content, the formation of the Fe-Al inhibition layer and weldability were also influenced by the Mg addition.Mg addition, corrosion resistance, galvanized and galvannealed coatingsM.-H. Hong, D.-G. Kang, D.-J. Paik, H.-S. Hwang, and S.-H. Park, Korean J. Met. Mater. 54, 723 (2016).10.3365/KJMM.2016.54.10.723Corrosion & Surface Treatment20165411817825Effects of Induction Heat Bending and Heat Treatment on the Boric Acid Corrosion of Low Alloy Steel Pipefor Nuclear Power PlantsKi-Tae KimMin-Chul Shin, Hyun-Young Chang, Heung-Bae Park, Gi-Ho Sung, and Young-Sik KimAndongNational University, KEPCO E&C, Sungil SIM Co. LtdIn many plants, including nuclear power plants, pipelines are composed of numerous fittings such as elbows. When plants use these fittings, welding points need to be increased, and the number of inspections also then increases. As an alternative to welding, the pipe bending process forms bent pipe by applying strain at low or high temperatures. This work investigates how heat treatment affects on the boric acid corrosion of ASME SA335 Gr. P22 caused by the induction heat bending process. Microstructure analysis and immersion corrosion tests were performed. It was shown that every area of the induction heat bent pipe exhibited a high corrosion rate in the boric acid corrosion test. This behavior was due to the enrichment of phosphorous in the ferrite phase, which occurred during the induction heat bending process. This caused the ferrite phase to act as a corrosion initiation site. However, when re-heat treatment was applied after the bending process, it enhanced corrosion resistance. It was proved that this resistance was closely related to the degree of the phosphorus segregation in the ferrite phase.low alloy steel, induction heat bending, boric acid corrosion, phosphorusK.-T. Kim, M.-C. Shin, H.-Y. Chang, H.-B. Park, G.-H. Sung, and Y.-S. Kim, Korean J. Met. Mater. 54, 817 (2016).10.3365/KJMM.2016.54.11.817Corrosion & Surface Treatment20165412885892(Sour) Effects of Alloying Elements on the Corrosion Properties of High StrengthSteel in a Sour EnvironmentYoungmin HyunHeesan KimSchool of Mater. Sci. and Eng. Hongik UniversityThe effects of alloying elements (Mn, Cr, and C) on the corrosion resistance of steel were examined using weight loss test, polarization test in a sour environment, analysis of rust, and the prediction of stable corrosion product. Carbon was found to improve corrosion resistance after 7-day immersion, while manganese and chromium negatively affected the corrosion resistance of steels during the entire immersion time. The negative effect of manganese and chromium on the corrosion resistance in the sour environment was explained, in that both manganese and chromium were stable as ionic species were dissolved in the sour solution, which was proved by the prediction of stable phases based on phase equilibria. The positive effect of carbon, on the other hand, was due to the formation of amorphous carbon distributed near the metal/rust interface, which may improve the adhesion of the corrosion product to the matrix. This is consistent with not only the formation of adhesive rust on the high carbon-containing steels but also the change in the corrosion behaviour of the high carbon-containing steels, from linear to parabolic behaviour, with time.alloys, hot rolling, corrosion, TEM, E-pH diagramY. Hyun and H. Kim, Korean J. Met. Mater. 54, 885 (2016).10.3365/KJMM.2016.54.12.885Corrosion & Surface Treatment20175529197Fe-(20, 45) wt% Gd Study on the Mechanical Properties and Corrosion Behaviors of Fe-(20, 45) wt% Gd IntermetallicsBo Kyeong KangYoul Baik, Yong Choi, and Byung Moon MoonDankook University, Department of Materials Science and EngineeringFe-(20, 45 wt%) Gd intermetallics were vacuum arc melted as the mother alloy of a neutron shielding and absorbing material. The structure of the cast Fe-20 wt% Gd intermetallics had primary dendrites with a short width of about 2 m, which became coarse with increasing Gd content. The final compositions of the Fe-20 wt% Gd and Fe-45 wt% Gd intermetallics determined by Rietveld refinementwere mainly Fe3Gd with 26.6 at% Fe2Gd, and Fe3Gd with various intermetallics like 13.9 at% Fe2Gd, 7.3 at% Fe9Gd and 3.9 at% Fe17Gd2, respectively. The micro-hardnesses, yield strength, ultimate compressive strength and elongation of the Fe-20 wt% Gd intermetallics were 62912 Hv, 753 MPa, 785 MPa and 4%,respectively, and those of the Fe-45 wt% Gd intermetallics were 74113 Hv, 772 MPa, 823 MPa and 3%. Passivity was not present in artificial sea water at room temperature. The corrosion potentials and the corrosion rates of the Fe-20 wt% Gd and Fe-45 wt% Gd intermetallics were 624 mVSHE, 2.771 mA/cm2, and 804 mVSHE, 3.397 mA/cm2, respectively. The corroded surface of the Fe-Gd intermetallics contained corrosion products like gadolinium with iron, which detached to leave a trail of pits.gadolinium, gd intermetallics, rietveld refinement, mechanical properties, corrosion behaviorsB. K. Kang, Y. Baik, Y. Choi, and B. M. Moon, Korean J. Met. Mater. 55, 91 (2017).10.3365/KJMM.2017.55.2.91

Electronic Materials DOIElectronic Materials2015532123132N- Bi2 (Te0.95 Se0.05)3 Characterization of the Structural Modulations in n-type Bi2 (Te0.95Se0.05)3 Thermoelectric CompoundSung Ho YoonKap Ho Lee, Soon Jik HongChungnam National University, Kongju National UniversityAn n-type Bi2Te3 thermoelectric compound was analyzed by using a high resolution transmission electron microscopy, and was further analyzed by using an image processing unit. A sinusoidal strain contrast of the structural modulations appeared in a multi-beam image and the fringes showed a wavelength of 12 nm with a wave vector parallel to the {101.10} planes. A numerous dislocations were found to glide on to the (0001) plane with a Burgers vector of 1/3-type on the strain field. In order for the elastic strain energy to be relieved, the resultant 1/3-type dislocation was thought to be dissociated into two partial dislocations gliding on the {1.015} planes. The variation in stacking periodicity of the 5-layers lamellar structure with respect to the basal plane of Bi2Te3 was also observed locally. However, this stacking variation is not responsible for the formation of structural modulations. The displacement of the sinusoidal strain field on the structural modulations seems to be generated by dislocation, with presence of dipoles that are about a few nanometers apart. It is understandable that phonons should be scattered throughout the strain field of the structural modulation. Hence, the lattice thermal conductivity is expected to be decreased due to the phonon scattering on sinusoidal strain field of the structural modulations.thermoelectric materials, structural modulations, dislocation, transmission electron microscopy(TEM), extrusionSung Ho Yoon, Kap Ho Lee, and Soon Jik Hong, Korean J. Met. Mater. 53, 123 (2015).10.3365/KJMM.2015.53.2.123Electronic Materials2015533192197Selenization CuInSe2 Change in the Properties of CuInSe2 Thin Film according to Selenization pressure conditionsGwanghoon ParkYounghee Ko, Hang-Ju Ko, Jun-Seok HaChonnam University, Korea Photonics Technology InstituteWe studied the physical properties of CuInSe2(CIS) thin films fabricated using a cracked selenium (Se) source in the selenization processes. The crystalline CIS films were characterized by energy-dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM), X-ray diffraction (XRD), and a Hall effect measurement system. Precursors with the same amount of Se were prepared with a co-sputtering system equipped with Se Knudsen cells. The precursors were heated under four kinds of Se pressure conditions (0.02, 0.1, 1, 2 Pa) for 15 minutes at 425 , which is a selenization process for crystalline CIS films. The low Se pressure conditions in selenization processes were more reactive than the higher Se pressure conditions. The Se pressure in selenization tends to increase the CIS grain size, which was confirmed by investigation of the surface morphology of SEM and of the crystal size in the XRD. We found that the Se pressure in the selenization processes influences the preferred crystalline orientations and the electrical properties of CIS thin films.solar cells, sputtering, interfaces, X-ray diffraction, CuInSe2 filmGwanghoon Park, Younghee Ko, Hang-Ju Ko, and Jun-Seok Ha, Korean J. Met. Mater. 53, 192 (2015).10.3365/KJMM.2014.53.3.192Electronic Materials2015533198205V2O5-P2O5 B2O3 (II)Effects of Substituting B2O3 for P2O5 on the Structures and Properties of V2O5-P2O5 Glass Systems (II)Su-Yeon ChoiYoung-Seok Kim, Jong-Hwan Kim, Jae-Yeop Jung, Il-Gu Kim, Hyun-Joon Park,Jong-Sung Bae, Bong-Ki RyuPusan National University, Korea Basic Science Institute Busan CenterIn this study, we verify the relationship among the catalytic effect, electrical conductivity, and structure of vanadium borophosphate glasses that have a coincidence of BO3 and BO4 and a coincidence of V4+ and V5+. We prepared vanadium borophosphate glasses with various compositions, given by 70V2O5- xB2O3-(70-x) P2O5(x=0-10mol%), and analyzed the catalytic effect, electrical conductivity, FT-IR spectroscopy, X-ray photoelectron spectroscopy, thermal properties, density, and molar volume. In V2O5-P2O5 binary glasses, the electrical conductivity increased from 0. 4073 ? 10.7/ to 20.167 ? 10.7/ but the catalytic effect for oxidation reactions of linoleic and stearic acid decreased with an increasing B2O3. From these results, we can deduce that electrons shift from V4+ to V5+ with an increasing B2O3. FT-IR analysis showed an occurrence peak at 680 cm.1 and XPS analysis showed that a V4+ decrease and a V5+ increase are the basis of the electron shift from V4+ to V5+. We also verify the structure and change in properties from quantitative properties such as thermal properties, density, and molar volume.glasses, solidification, electrical conductivity, thermal analysis, catalytic effectSu-Yeon Choi, Young-Seok Kim, Jong-Hwan Kim, Jae-Yeop Jung, Il-Gu Kim, Hyun-Joon Park, Jong-Sung Bae, and Bong-Ki Ryu, Korean J. Met. Mater. 53, 198 (2015).10.3365/KJMM.2014.53.3.198Electronic Materials2015534287293Electrical Conductivity of Ni-YSZ Anode for SOFCs According tothe Ni Powder Size Variations in Core-shell StructureElectrical Conductivity of Ni-YSZ Anode for SOFCs According tothe Ni Powder Size Variations in Core-shell StructureYoung Jin KangSung-Hun Jung, Yong-Tae An, Byung-Hyun Choi, Mi-Jung JiKorea Institute of Ceramic Engineering & Technology (KICET)Ni-YSZ (Y2O3-stabilized ZrO2) core-shell structures were prepared by a high-speed mixing method,starting from Ni particles of three different average sizes of 0.2, 0.4, and 1.8 m. The Ni-YSZ core-shellstructures prepared using Ni particles of size 0.2, 0.4, and 1.8 m exhibited dense core, porous core, andrandom-morphology core, respectively. Subsequently, nanostructured cermet anodes were fabricated usingthe prepared Ni-YSZ core-shell powders. During the formatio