1992년도 추계 학술강연 및 발표대회 개요 - 재료물성 ( 발표 21 ) : 금속복합재료의 젖음성 향상을 위한 섬유 피복 방법

백경호,성환진,이규창 대한금속재료학회 ( 구 대한금속학회 ) 1992 대한금속재료학회 학술대회 개요집 Vol.1992 No.1

기계적 합성된 분말로부터 펄스전류활성 소결에 의한 나노구조 Ti3Al-Al2O3 복합재료 제조 및 기계적 특성

손인진 ( In Jin Shon ),왕희지 ( Hee Ji Wang ),서창열 ( Chang Yul Suh ),조성욱 ( Sung Wook Cho ),김원백 ( Won Baek Kim ) 대한금속재료학회(구 대한금속학회) 2011 대한금속·재료학회지 Vol.49 No.5

Nano-powders of Ti3Al and 2(Al2O3) were synthesized from 3Ti(O2) and 5Al powders by high energy ball milling. A nanocrystalline Al2O3 reinforced composite was consolidated by pulsed current activated sintering within 2 minutes from mechanochemically synthesized powders of Al2O3 and Ti3Al. Nanocrystalline materials, have received much attention as advanced engineering materials due to their improved physical and mechanical properties. The relative density of the composite was 99.5%. The average obtained hardness and fracture toughness values were 1510 kg/mm2 and 9 MPa·m1/2, respectively.

와이어 브러싱한 알루미늄 판재 표면 및 압연접합 계면의 미세조직 및 기계적 성질

김수현 ( Su Hyeon Kim ),김형욱 ( Hyoung Wook Kim ),강주희 ( Joo Hee Kang ),어광준 ( Kwang Jun Euh ) 대한금속재료학회(구 대한금속학회) 2011 대한금속·재료학회지 Vol.49 No.5

Wire brushing, which is a typical surface preparation method for roll bonding, has recently been highlighted as a potentially effective method for surface nanocrystallization. In the present study, the microstructure evolution and hardness of the wire-brushed surface and roll-bonded interface of a 1050 aluminum sheet were investigated. Wire brushing formed protruded layers with a nanocrystalline structure and extremely high surface hardness. After roll bonding, the protruded layers remained as hard layers at the interface. Due to their hardness and brittleness the interface hard layers, can affect the interface bonding properties and also play an important role determining the mechanical properties of multi-layered clad sheets.

균일침전법을 이용한 아나타제형 TiO2 분말의 제조 및 특성 평가

최순옥 ( Soon Ok Choi ),조지희 ( Jee Hee Cho ),임성환 ( Sung Hwan Lim ),정은영 ( Eun Young Chung ) 대한금속재료학회(구 대한금속학회) 2011 대한금속·재료학회지 Vol.49 No.5

This paper studies the experimental method that uses the homogeneous precipitation method to prepare mica flakes coated with anatase-type titania pearlescent pigment with urea as precipitant. The optimum technology parameters, the chemical composition, the microstructure, and the color property of resulting pigments are discussed. The coating principle of mica coated titania with various coating thickness is analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy(TEM) and tested by spectrophotometer analysis. The colored nanocrystalline pigments with different morphology and coating thickness 45-170 nm were prepared by homogeneous precipitation treatment of TiOSO4(titanum oxysulfate) aqueous solutions. Characterizations on the pigments show that the pearlescent effects of the pigments depend mainly on mica size, thickness of the metal oxide deposit, its chemical composition, and crystal structure.

루테늄이 첨가된 텅스텐 산화물을 이용한 마이크로 가스 센서의 암모니아 가스 감지 특성

이회중 ( Hoi Jung Lee ),윤진호 ( Jin Ho Yoon ),김범준 ( Bum Joon Kim ),장현덕 ( Hyun Duck Jang ),김정식 ( Jung Sik Kim ) 대한금속재료학회(구 대한금속학회) 2011 대한금속·재료학회지 Vol.49 No.5

In this study, micro gas sensors for ammonia gas were prepared by adopting MEMS technology and using a sol-gel process. Three types of sensors were prepared via different synthesis routes starting with W sol and Ru sol mixture. This mixture was deposited on a MEMS platform and the platform was subsegueny heated to a temperature of 350℃. The topography and crystal structure of the sensing film were studied using FE-SEM and XRD. The response of the gas sensor to NH3 gas was examined at various operating temperatures and gas concentrations. The sensor response increased almost linearly with gas concentration and the best sensing response was obtained at 333℃ for 5.0 ppm NH3 for the specimen prepared by coating WO3 powders with the Ru sol mixture.

플립칩 패키징용 Sn-0.7Cu 전해도금 초미세 솔더 범프의 제조와 특성

노명훈 ( Myong Hoon Roh ),이희열 ( Hea Yeol Lee ),김원중 ( Won Joong Kim ),정재필 ( Jae Pil Jung ) 대한금속재료학회(구 대한금속학회) 2011 대한금속·재료학회지 Vol.49 No.5

The current study investigates the electroplating characteristics of Sn-Cu eutectic micro-bumps electroplated on a Si chip for flip chip application. Under bump metallization (UBM) layers consisting of Cr, Cu, Ni and Au sequentially from bottom to top with the aim of achieving Sn-Cu bumps 10×10×6 ㎛in size, with 20㎛ pitch. In order to determine optimal plating parameters, the polarization curve, current density and plating time were analyzed. Experimental results showed the equilibrium potential from the Sn-Cu polarization curve is -0.465 V, which is attained when Sn-Cu electro-deposition occurred. The thickness of the electroplated bumps increased with rising current density and plating time up to 20 mA/cm2 and 30 min respectively. The near eutectic composition of the Sn-0.72wt%Cu bump was obtained by plating at 10 mA/cm2 for 20 min, and the bump size at these conditions was 10×10×6 ㎛. The shear strength of the eutectic Sn-Cu bump was 9.0 gf when the shearing tip height was 50% of the bump height.

Effect of Ni Addition on the Wear and Corrosion Resistance of Fe-20Cr-1.7C-1Si Hardfacing Alloy

( Sung Hoon Lee ),( Ki Nam Kim ),( Seon Jin Kim ) 대한금속재료학회(구 대한금속학회) 2011 대한금속·재료학회지 Vol.49 No.10

In order to improve the corrosion resistance of Fe-20Cr-1.7C-1Si hardfacing alloy without a loss of wear resistance, the effect of Ni addition was investigated. As expected, the corrosion resistance of the alloy increased with increasing Ni concentration. The wear resistance of the alloy did not decrease, even though the hardness decreased, up to Ni concentration of 5 wt.%. This was attributed to the fact that the decrease in hardness was counterbalanced by the strain-induced martensitic transformation. The wear resistance of the alloy, however, decreased abruptly with increases of the Ni concentration over 5 wt.%.

전기화학적 방법에 의한 산화아연 나노튜브의 합성과 형성 기구

문진영 ( Jin Young Moon ),김형훈 ( Hyung Hoon Kim ),이호성 ( Ho Seong Lee ) 대한금속재료학회(구 대한금속학회) 2011 대한금속·재료학회지 Vol.49 No.5

ZnO nanotube arrays were synthesized by a two-step process: electrodeposition and selective dissolution. In the first step, ZnO nanorod arrays were grown on an Au/Si substrate by using a homemade electrodeposition system. ZnO nanorod arrays were then selectively dissolved in an etching solution composed of 0.125 M NaOH, resulting in hollow ZnO nanotube arrays. It is suggested that the formation mechanism of the ZnO nanotube arrays might be attributed to the preferred surface adsorption of hydroxide ion (OH-1) on a positive polar surface followed by selective dissolution of the metastable Zn-terminated ZnO (0001) polar surface caused by the difference in the surface energy per unit area between the ZnO nanorod and nanotube.

전자석 시스템의 절연 구조물용 유리섬유강화 복합재료의 층간 파괴인성

송준희 ( Jun Hee Song ),김학근 ( Hak Kun Kim ),김연직 ( Yon Jig Kim ) 대한금속재료학회(구 대한금속학회) 2011 대한금속·재료학회지 Vol.49 No.10

In this study, the interlaminar fracture behaviors of laminated GFRP composites were investigated, and the results could be used for damage tolerance design based on fracture mechanics. Three types of laminated GFRP composites that can be used as high voltage insulating materials in magnet systems were fabricated in order to study the interlaminar fracture behavior according to the molding process. The values of interlaminar fracture toughness for the VPI, prepreg, and HPL laminate were 1.9 MPa · 1/2, 1.7 MPa · 1/2, and 2.2 MPa · 1/2, respectively. HPL laminate showed the best fracture resistance. The failure modes of HPL and VPI were similar to that of an adhesive joint, and prepreg laminates showed partial cohesive failure mode due to internal voids.

Influence of Calcium on the Formation of Aluminosilicate Inorganic Polymer Binder

( Sang Wook Ahn ),( Young Kue Choi ),( Byeong Kil Shin ),( Jung Woo Lee ),( Hee Soo Lee ),( Kwun Nam Hui ) 대한금속재료학회(구 대한금속학회) 2011 대한금속·재료학회지 Vol.49 No.5

Aluminosilicate inorganic polymer binder has been studied as an alternative to ordinary Portland cement due to its higher physical properties, chemical resistance and thermal resistance. This study has been carried out in an attempt to understand the hardening characteristics of aluminosilicate binder by varying the content of calcium. Samples with four different ratios of Al, Si, and Ca were synthesized in this study with the Al:Si:Ca mol ratio being 1.00:1.85~1.98:0.29~2.12. Furthermore, an alkali silicate solution was prepared with the sodium hydroxide (NaOH) and sodium silicate (NaSi). The hardening characteristics of the specimens were analyzed using XRD, SEM, and TG/DTA. In addition, compressive strength and sintering time of specimens were measured as a function of calcium content. The results showed that the specimen containing 2.12 mol% calcium offered the highest compressive strength. However, the compressive strength of the specimen containing 0.26 mol% calcium was lower relative to the other specimens. The results displayed a distinct tendency that as more calcium was added to the inorganic polymer, setting time became shorter. When calcium was added to the inorganic polymer structure, a second phase was not formed, indicating that the addition of calcium does not affect the crystalline structure.