• Economic and Environmental Geology
• /
• v.25 no.1
• /
• pp.51-60
• /
• 1992

The pluton rocks in Kwangyang-Seungju area consist of two mica granite, hornblende diorite, Rimunri quartz diorite, grnodiorite porphyry and granophyre. The analysis of the geochronological data by the methods of K-Ar for the hornblende from Rimunri quartz diorite and hornblende diorite show that the ages are found to be $86{\pm}3.3$ Ma and $108{\pm}4$ Ma, respectively, and K-Ar age for chlorite from the altered two mica granite which intruded by the hornblende diorite of the Bonjeong mine shows $108{\pm}4$ Ma; K-Ar age for sericite from the greisenized hornblende diorite, which is closely associated with the Bonjeong ore deposits, is dated as $94.2{\pm}2.4$ Ma. They correspond to the igneous activity of the Bulgugsa Disturbance periods in the area. In chemical feature for oxides versus silica and AFM triagular diagrams of the pluton rocks in the study area, there is a suggestion of the possibility that these rock facies area a Calc-alkali series of differentiated products by low-pressure crystal fractionation processes in $SiO_2$-undersaturated suites. Compared with hornblende diorite, andesite and granodiorite porphyry, two mica granite, Rimunri quartz diorite and granophyre exhibit a wider range of normalized REE abundance and negative Eu anomalies. Such anomalies imply more extensive feldspar fractionation during crystallization. The Rimunri quartz diorite and hornblende diorite occurring in the margin of four mines(Bonjeong, Okdong, Soungchei and Saungyeul) of this area have high contents of As, Sb, Cu and Zn which have been shown as the best indicators in hypogene gold deposits and low contents of Ba, Cr served as more sensitive indicators. And the granitoids are regarded as the rocks associated with gold and sulfide mineralization of the area.

• Proceedings of the Korean Institute of Surface Engineering Conference
• /
• 2018.06a
• /
• pp.69.1-69.1
• /
• 2018

산업 현장에서 자주 사용되는 알루미늄 합금은 순도가 높은 알루미늄에 비해 경제성, 기계적 성질이 우수한 장점이 있다. 하지만 이런 합금들은 물리적, 화학적 성질이 순수 알루미늄과 달라 양극산화와 같은 표면처리가 쉽지 않다. 양극산화는 표면처리 기술의 대표적인 방법 중 하나로 인위적으로 산화피막을 형성하는 기술이다. 순도가 높은 알루미늄은 산성 전해질에서의 양극산화를 통해 다공성 산화피막을 형성할 수 있으며 그 구조로 인해 내식성, 내마모성 등 기계적, 화학적인 다양한 장점이 있다. 하지만, Mg, Si, Cr과 같은 성분이 함유된 알루미늄의 경우 산성 전해질에서 산화물을 형성되지 않는다. 본 연구에서 기존의 산성 전해질에서의 양극산화 방법이 아닌$K_2HPO_4$를 함유하는 고온의 글리세롤 전해질을 사용하여 양극산화를 진행하였다. 사용한 알루미늄은 산업용으로 자주 사용되는 3000계열의 알루미늄을 사용하였으며 균일한 양극산화를 위해 샌드페이퍼를 통한 연마과정을 통해 표면을 평탄화 하였다. 이후 전기화학적 에칭 과정을 거쳐 표면에 있는 자연산화막을 제거하여 표면 분석을 용이하게 하였다. 양극산화는 10wt%의 $K_2HPO_4$/글리세롤 전해질에서 전해질의 온도와 인가 전압을 달리 하여 진행하였다. 결과 $150^{\circ}C$ 이상의 온도에서 알루미늄 합금의 양극산화를 확인할 수 있었고 $170^{\circ}C$의 온도에서 인가 전압을 20V로 하였을 때 가장 정렬된 다공성 구조를 얻을 수 있었다. 본 연구 결과를 통해 산업용 알루미늄 합금의 양극산화를 통해 다공성 나노구조 산화물을 형성 시킬 수 있었다.

• Journal of Sensor Science and Technology
• /
• v.16 no.6
• /
• pp.419-427
• /
• 2007

Single crystal $ZnIn_{2}S_{4}$ layers were grown on a thoroughly etched semi-insulating GaAs(100) substrate at $450^{\circ}C$ with the hot wall epitaxy (HWE) system by evaporating the polycrystal source of $ZnIn_{2}S_{4}$ at $610^{\circ}C$ prepared from horizontal electric furnace. The crystalline structure of the single crystal thin films was investigated by the photoluminescence and double crystal X-ray diffraction (DCXD). The carrier density and mobility of single crystal $ZnIn_{2}S_{4}$ thin films measured with Hall effect by van der Pauw method are $8.51{\times}10^{17}\;electron/cm^{-3}$, $291{\;}cm^{2}/v-s$ at 293 K, respectively. The photocurrent and the absorption spectra of $ZnIn_{2}S_{4}$/SI(Semi-Insulated) GaAs(100) are measured ranging from 293 K to 10 K. The temperature dependence of the energy band gap of the $ZnIn_{2}S_{4}$ obtained from the absorption spectra was well described by the Varshni's relation, $E_g(T)$=2.9514 eV. ($7.24{\times}10^{-4}\;eV/K$)$T^{2}$/(T+489 K). Using the photocurrent spectra and the Hopfield quasicubic model, the crystal field energy(${\Delta}cr$) and the spin-orbit splitting energy(${\Delta}so$) for the valence band of the $ZnIn_{2}S_{4}$ have been estimated to be 167.8 meV and 14.8 meV at 10 K, respectively. The three photocurrent peaks observed at 10 K are ascribed to the $A_{1}$-, $B_{1}$-, and $C_{41}$-exciton peaks.

• Corrosion Science and Technology
• /
• v.11 no.1
• /
• pp.9-14
• /
• 2012

The formation of the Fe-Al inhibition layer in hot-dip galvanizing is a confusing issue for a long time. This study presents a characterization result on the inhibition layer formed on C-Mn-Cr and C-Mn-Si dual-phase steels after a short time galvanizing. The samples were annealed at $800^{\circ}C$ for 60 s in $N_{2}$-10% $H_{2}$ atmosphere with a dew point of $-30^{\circ}C$, and were then galvanized in a bath containing 0.2 %Al. X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) was employed for characterization. The TEM electron diffraction shows that only $Fe_{2}Al_{5}$ intermetallic phase was formed. No orientation relationship between the $Fe_{2}Al_{5}$ phase and the steel substrate could be identified. Two peaks of Al 2p photoelectrons, one from metallic aluminum and the other from $Al^{3+}$ ions, were detected in the inhibition layer, indicating that the layer is in fact a mixture of $Fe_{2}Al_{5}$ and $Al_{2}O_{3}$. TEM/EDS analysis verifies the existence of $Al_{2}O_{3}$ in the boundaries of $Fe_{2}Al_{5}$ grains. The nucleation of $Fe_{2}Al_{5}$ and the reduction of the surface oxide probably proceeded concurrently on galvanizing, and the residual oxides prohibited the heteroepitaxial growth of $Fe_{2}Al_{5}$.

• Transactions of Materials Processing
• /
• v.24 no.1
• /
• pp.44-51
• /
• 2015

The current study seeks to examine the effects of V and C additions on the mechanical and low thermal expansion properties of a high strength invar base alloy. The base alloy (Fe-36%Ni-0.9%Co-2.75%Mo-0.7Cr-0.23Mn-0.17Si-0.3%C, wt.%) contains $Mo_2C$ carbides, which form as the main precipitate. In contrast, alloys with additions of 0.4%V+0.3%C (alloy A) or 0.4%V+0.45%C (alloy B) contain $Mo_2C$+[V, Mo]C carbides. The average thermal expansion coefficients of these high strength invar based alloys were measured in the range of $5.16{\sim}5.43{\mu}m/m{\cdot}^{\circ}C$ for temperatures of $15{\sim}230^{\circ}C$. Moreover, alloy B showed lower thermal expansion coefficient than the other alloys in this temperature range. For the mechanical properties, the [V, Mo]C improved hardness and strengths(Y.S. and T.S.) of the high strength invar base alloy. T.S.(tensile strength) and Y.S.(yield strength) of hot forged alloy B specimen were measured at 844.6MPa and 518.0MPa, respectively. The tensile fractography of alloy B exhibited a ductile transgranular fracture mode and voids were initiated between the [V, Mo]C particles and the matrix. Superior properties of high strength and low thermal expansion coefficient can be obtained by [V, Mo]C precipitation in alloy B with the addition of 0.4%V and 0.45%C.

• Journal of Korean Society of Water and Wastewater
• /
• v.14 no.4
• /
• pp.303-310
• /
• 2000

This study is conducted in order to find more improved solidifying effects than the former converter slag solidification technology. The converter slag is used as a solidifying agent, and the quick lime and the gypsum are used as solidifying aids. Several tests are performed for the purpose of investigating the solidifying effects and the applicability of the solidified sludge as a daily or intermediate landfill cover. The unconfined uniaxial compressive strength, pH and leaching of heavy metal are investigated. In the case of using both quick lime and gypsum as solidifying aids, the compressive strength of specimen has significantly increased that of specimen which used quick lime only. The compressive strength of each specimen cured for 7 days which is mixed with quick lime and gypsum as mixing ratios 7:1, 5:1 and 3:1 are $0.59kg/cm^2$, $1.18kg/cm^2$, and $1.25kg/cm^2$, respectively. The results of all the leaching tests of specimen cured for 7 days show that the concentrations of leachate heavy metals(Cu, Pb, Cd and $Cr^{6+}$) are lower than the Korea toxic waste criteria. The microstructure analysis by SEM shows that needlelike crystals appear as the solidification proceed. The analysis of these crystals by EDS confirms that these main components are Ca. Si etc. Also, XRD analysis shows that the main solidification products are CSH and Ettringite; in addition, $Ca(OH)_2$ CAH are observed. When the added gypsum is used as a solidifying aid, more improved solidifying effects are obtained and the solidified sludge may be appropriately used as a daily or intermediate landfill cover.

• Journal of Powder Materials
• /
• v.18 no.5
• /
• pp.430-436
• /
• 2011

Joining of NiO-YSZ to 316 stainless steel was carried out with B-Ni2 brazing alloy (3 wt% Fe, 4.5 wt% Si, 3.2 wt% B, 7 wt% Cr, Ni-balance, m.p. 971-$999^{\circ}C$) to seal the NiO-YSZ anode/316 stainless steel interconnect structure in a SOFC. In the present research, interfacial (chemical) reactions during brazing at the NiO-YSZ/316 stainless steel interconnect were enhanced by the two processing methods, a) addition of an electroless nickel plate to NiO-YSZ as a coating or b) deposition of titanium layer onto NiO-YSZ by magnetron plasma sputtering method, with process variables and procedures optimized during the pre-processing. Brazing was performed in a cold-wall vacuum furnace at $1080^{\circ}C$. Post-brazing interfacial morphologies between NiO-YSZ and 316 stainless steel were examined by SEM and EDS methods. The results indicate that B-Ni2 brazing filler alloy was fused fully during brazing and continuous interfacial layer formation depended on the method of pre-coating NiO-YSZ. The inter-diffusion of elements was promoted by titanium-deposition: the diffusion reaction thickness of the interfacial area was reduced to less than 5 ${\mu}m$ compared to 100 ${\mu}m$ for electroless nickel-deposited NiO-YSZ cermet.

• Journal of IKEEE
• /
• v.19 no.4
• /
• pp.535-540
• /
• 2015

A microstrip gas chamber (MSGC), applied to digital radiography system, was designed and constructed. The microstrip electrodes were fabricated with Chrome(Cr.). by photolithography process on Silicon(Si) wafer and glass substrate. The width of anode and cathode electrodes was $10{\mu}m$, and $290{\mu}m$, respectively. The distance of the electrodes was $100{\mu}m$, and the active area was $50{\times}50mm^2$. And the number of anode was 80. The microstrip electrodes were damaged when discharges occurred over the 600 V of anode voltage. As the result of experiments. It detected the typical output signals of the pulse width, 20 ns, under the condition that the detecting gas was Ar(90%) + $CH_4$(10%), X-ray tube voltage was 42 kV, and tube current was 1 mA.

• Proceedings of the Korean Vacuum Society Conference
• /
• 1999.07a
• /
• pp.139-139
• /
• 1999

다이아몬드는 지구상에서 가장 단단한 물질로 잘 알려져 있을 뿐만 아니라 공업적 측면에서 볼 때, 여러 가지 특출한 성질들을 동시에 지니고 있다. 인장강도, 압축강도, 탄성계수 등 기계적 특성이 우수하고 넓은 광투과성과 내열, 내화학, 내방사성을 지니고 있으며, 열전도율이 높고 전기적으로 절연체이다. 또한 hole이동도가 높고 도핑에 의해서 반도체적 특성을 나타낸다. 이와 같이 매우 뛰어난 성질을 공업적으로 응용하기 위하여 이전부터 많은 연구가 행해져 왔으며, 1980년대에 들어와 박막이나 코팅 형태로의 합성이 가능한 기상합성법이 큰 발전을 보임으로써 다이아몬드의 우수한 특성을 여러 분야에서 폭넓게 응용할 수 있게 되었다. 특히 마찰 응용분야에 최적의 재료로 추천되고 있다. 지금도 Epitaxial 다이이몬드를 기지 위에 성장시키고 다결정질박막을 여러 가지 비다이아몬드(Si, W, Mo 등) 기지 위에 성장시키는 연구가 계속되고 있으며 공구강 위엥 경질코팅으로써 한층 개선된 다이아몬드박막 제조를 위한 수많은 연구노력들이 집중되고 있다. 그러나 일반탄소강에 다이아몬드박막을 성장시키기 위한 많은 노력들은 크게 바람직하지 않은 non-diamond carbon(black carbon or graphitic soot)의 형성 때문에 방해를 받고 있다. 계면에서 이들의 형성은 증착된 다이아몬드박막과 금속기지의 저조한 밀착력을 나타내게 된다. 이외 같이 다이아몬드박막의 응용을 위하여 다이아몬드피막에 요구되는 중요한 조건은 기지에 대해서 강한 밀착력을 나타내는 것이며, 동시에 상대물에 대하여 낮은 마찰계수를 가져야 한다. 그러나 다이아몬드와 금속기지는 서로 다른 열챙창계수(각각 0.87$\times$10-6K-1, 12$\times$10-6K-1)의 차이로 인하여 밀착력이 현저히 떨어진다는 단점으로 인해 산업화에 많은 제약을 받아왔다. 이러한 문제점을 해결하기 위하여 본 연구에서는 다이아몬드박막과 금속기지 사이에 중간층을 이용하는 방법을 제안하였다. 이러한 시도는 일반적으로 중간층 형성 금속인 Ti 또는 TiN 등이 적용되었으나 원하는 결과를 얻지 못하였다. 즉 carbon과 Fe의 상호확산, non-diamond carbon상의 형성 그리고 열잔류응력을 완화시키고 일반탄소강 위에 다이아몬드박막을 형성시켜 우수한 밀착력을 얻기 위한 목적에 미흡하였던 것이다. 이에 중간층으로 Cr 또는 Cr계 화합물 박막을 이용하였는 바, 이 중간층을 이용한 결과 우수한 밀착력을 나타내는 다이아몬드박막을 얻었으며 열적, 구조저으로 모재와 다이아몬드에 적합한 결과를 얻을 수 있었다. 본 연구에 의해 얻어진 결과들은 재료 가공을 위하여 높은 경도와 내마모성등이 요구되는 절삭공구나 금형의 수명 향항에 크게 기여할 것이며 산업적으로 큰 응용이 기대된다.

• Transactions on Electrical and Electronic Materials
• /
• v.3 no.1
• /
• pp.30-37
• /
• 2002

A focusing grating coupler (FGC) was not fabricated by the 'Continuous Path Control'writing strategy but by an electron-beam lithography system of more general exposure mode, which matches not only the address grid with the grating period but also an integer multiple of the address grid resolution (5 nm). To more simplify the fabrication, we are able to reduce a process step without large decrease of pattern quality by excluding a conducting material or layer such as metal (Al, Cr, Au), which are deposited on top or bottom of an e-beam resist to prevent charge build-up during e-beam exposure. A grating pitch period and an aperture feature size of the FGC designed and fabricated by e-beam lithography and reactive ion etching were ranged over 384.3 nm to 448.2 nm, and 0.5 $\times$ 0.5 mm$^2$area, respectively. This fabrication method presented will reduce processing time and improve the grating quality by means of a consideration of the address grid resolution, grating direction, pitch size and shapes when exposing. Here our investigations concentrate on the design and efficient fabrication results of the FGC for coupling from slab waveguide to a spot in free space.