• Journal of Welding and Joining
• /
• 제25권5호
• /
• pp.45-50
• /
• 2007

The Ni-base superalloy GTD111 DS is used in the first stage blade of high power land-based gas turbines. Advanced repair technologies of the blade have been introduced to the gas turbine industry over recent years. The effect of the filler metal powder on Transient Liquid Phase bonding phenomenon and tensile mechanical properties was investigated on the GTD111 DS superalloy. At the filler metal powder N series, the base metal powders fully melted at the initial time and a large amount of the base metal near the bonded interlayer was dissolved by liquid inter metal. Liquid filler metal powder was eliminated by isothermal solidification which was controlled by the diffusion of B into the base metal. The solids in the bonded interlayer grew from the base metal near the bonded interlayer inward the insert metal during the isothermal solidification. The bond strength of N series filler metal powder was over 1000 MPa. and ${\gamma}'$ phase size of N series TLP bonded region was similar with base metal by influence of Ti, Al elements. At the insert metal powder M series, the Si element fluidity of the filler metal was good but microstructure irregularity on bonded region because of excessive Si element. Nuclear of solids formed not only from the base metal near the bonded interlayer but also from the remained filler metal powder in the bonded interlayer. When the isothermal solidification was finished, the content of the elements in the boned interlayer was approximately equal to that of the base metal. But boride and silicide formed in the base metal near the bonded interlayer. And these boride decreased with the increasing of holding time. The bond strength of M series filler metal powder was about 400 MPa.

• 한국세라믹학회지
• /
• 제25권2호
• /
• pp.143-153
• /
• 1988

김천규석으로부터 합성한 질화규소와 시약급의 AIN과 $Y_2O_3$를 출발원료로 하여 $Si_3N_4-0.1Y_2O_3-0.9AIN$의 tie line에서 X=0.6, 0.4(금속고용량)인 조성으로부터 AIN 의 양을 감소시킨 조성과 $Y_2O_3$를 증가시키는 조성으로 1750~1800도에서 소결시켜 부분 안정화 $\alpha$-Sialon을 제조하였다. $\alpha$-Sialon 생성에는 $Y_2O_3$ 첨가량보다 AIN 첨가량에 밀접하게 관련되며 AIN은 $\beta$단위격자 보다 $\alpha$ 단위격자로 우선적으로 고용되었으며 $Y_2O_3$가 과잉으로 첨가된 조성에서는 melillite 형성과 입자 조대화 및 $\alpha$-Sialon의 분배로 인하여 yttrium silicide 와 금속 Si를 형성하였으며 기계적 물성은 저하하였다. 본 실험에서 얻은 기계적 물성의 최고 값은 모두 1780도에서 얻어졌으며 그 값은 꺽임강도 723MPa, 파괴 인성 4.5MN/m^3/2, 경도 19.3GPa이었다.

• Nuclear Engineering and Technology
• /
• 제45권7호
• /
• pp.847-858
• /
• 2013

Since 2001, a series of five irradiation test campaigns for atomized U-Mo dispersion fuel rods, KOMO-1, -2, -3, -4, and -5, has been conducted at HANARO (Korea) in order to develop high performance low enriched uranium dispersion fuel for research reactors. The KOMO irradiation tests provided valuable information on the irradiation behavior of U-Mo fuel that results from the distinct fuel design and irradiation conditions of the rod fuel for HANARO. Full size U-Mo dispersion fuel rods of 4-5 $g-U/cm^3$ were irradiated at a maximum linear power of approximately 105 kW/m up to 85% of the initial U-235 depletion burnup without breakaway swelling or fuel cladding failure. Electron probe microanalyses of the irradiated samples showed localized distribution of the silicon that was added in the matrix during fuel fabrication and confirmed its beneficial effect on interaction layer growth during irradiation. The modifications of U-Mo fuel particles by the addition of a ternary alloying element (Ti or Zr), additional protective coatings (silicide or nitride), and the use of larger fuel particles resulted in significantly reduced interaction layers between fuel particles and Al.

• 한국재료학회지
• /
• 제10권4호
• /
• pp.301-304
• /
• 2000

Si FEA로 부터 tip의 표면을 Co 금속으로 silicidation한 새로운 3극형 Co-silicided Si FEA를 제작하고 이의 전계 방출특성을 조사하였다. $10^{-8}Torr$의 고진공상태에서 제작된 소자의 단위 pixel(pixel 면적 : $250{\mu\textrm{m}}{\times}250{\mu\textrm{m}}$, tip 어레이 : $45{\times}45$)를 통해 측정된 turn-on 전압은 약 35V로, 아노드 전류는 $V_A=500V,\;V_G=55V$ 바이어스 아래에서 약 $1.2{\mu\textrm{A}}(0.6nA/tip)$로 나타났다. 제작된 소자는 초기 과도상태를 제외하면 장시간의 동작을 통해 전계방출 전류의 감소없이 매우 안정된 전기적 특성을 나타내었다. Co-silicided Si FFA 의 낮은 turn-on 전압과 높은 전류안전성은 Si tip 표면에 형성된 실리사이드 박막의 열화학적 안전성과 낮은 일함수에 기인하는 것으로 판단된다.

• 한국재료학회지
• /
• 제14권5호
• /
• pp.305-309
• /
• 2004

Mechanical alloying (MA) of Ti-25.0～37.5at%Si powders was carried out in a high-energy ball mill, and in situ thermal analysis was also made during MA. In order to classify the synthesis behavior of the powders with respect to at%Si, the synthesis behavior during MA was investigated by in situ thermal analysis and X-ray diffraction (XRD). In situ thermal analysis curves and XRD patterns of Ti-25.0～26.1at%Si powders showed that there were no peaks during MA, indicating $Ti_{5}$ $Si_3$ was synthesised by a slow reaction of solid state diffusion. Those of Ti-27.1～37.5at%Si powders, however, showed that there were exothermic peaks during MA, indicating $_Ti{5}$ $Si_3$ and$ Ti_3$Si phase formation by a rapid exothermic reaction of self-propagating high-temperature synthesis (SHS). For Ti-27.1～37.5at%Si powders, the critical milling times for SHS decreased from 38.1 to 18.5 min and the temperature rise, ΔT (= peak temperature - onset temperature) increased form $19.5^{\circ}C$ to $26.7^{\circ}C$ as at%Si increased. The critical composition of Si for SHS reaction was found to be 27.1at% and the critical value of the negative heat of formation of Ti-27.1at%Si to be -1.32 kJ/g.

• 한국재료학회지
• /
• 제10권11호
• /
• pp.738-741
• /
• 2000

사이클로펜타디에닐 디카보닐 코발트 (Co(η(sup)5-C(sub)5H(sub)5) ($CO_2$)의 반응성 화학 기상 증착법에 의해 $600^{\circ}C$ 근처의기판온도에서 (100)Si 기판 위에 균일한 에피택셜 CoSi2 층이 후열처리를 거치지 않고 직접 성장되었다. (100) Si 기판 위에서 에피택셜 CoSi(sub)2 층의 성장 속도론을 $575^{\circ}C$에서 $650^{\circ}C$의 온도 구간에서 조사하였다. 증착 초기 단계에서 판(plate)모양의 CoSi(sub)2 스차이크가 쌍정의 구조를 가지고 (100) Si 기판에서 <111> 방향을 따라서 불연속적으로 핵생성되었다. {111}과 (100)면을 가진 불연속의 CoSi(sub)2 판은 (100) Si 위에서 평평한 계면으로 이루어진 에피택셜 층으로 성장했다. (100) Si 위에서 에피택셜 CoSi(sub)2 층을 통한 Co의 확산에 의해 제어되는 것으로 나타났다.

• 한국전기전자재료학회논문지
• /
• 제16권7호
• /
• pp.573-578
• /
• 2003

Low temperature selective epitaxial growth of Si and SiGe has been obtained using an industrial single wafer chemical vapor deposition module operating at reduced pressure. Epitaxial Si and heteroepitaxial SiGe deposition with Ge content about 20 % has been studied as extrinsic base for self-aligned heterojunction bipolar transistors(HBTs), which helps to reduce the parasitic resistance to obtain higher maximum oscillation frequencies(f$\_$max/). The dependence of Si and SiGe deposition rates on exposed windows and their evolution with the addition of HCl to the gas mixture are investigated. SiH$_2$Cl$_2$ was used as the source of Si SEG(Selective Epitaxial Growth) and GeH$_4$ was added to grow SiGe SEG. The addition of HCl into the gas mixture allows increasing an incubation time even low growth temperature of 675∼725$^{\circ}C$. In addition, the selectivity is enhanced for the SiGe alloy and it was proposed that the incubation time for the polycrystalline deposit on the oxide is increased probably due to GeO formation. On the other hand, when only SiGe SEG(Selective Epitaxial Growth) layer is used for extrinsic base, it shows a higher sheet resistance with Ti-silicide because of Ge segregation to the interface, but in case of Si or Si/SiGe SEG layer, the sheet resistance is decreased up to 70 %.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2003년도 추계학술대회 논문집 Vol.16
• /
• pp.167-171
• /
• 2003

We report the material and electrical properties of $CoSi_2$ and $NiSi_2$contacts to n-type 4H-SiC depending on the post-annealing and the metal covering conditions. The Ni and Co silicides are deposited by RF sputtering with Ni/Si/Ni and Co/Si/Co films separately deposited on 4H-SiC substrates. The deposited films are annealed at $800\;^{\circ}C$ in $Ar:H_2$ (9:1) gas ambient. Results of the specific surface resistivity measurements show that the resistivity of the Co-based metal contact was the one order lower than that of the Ni-based contact. The specific contact resistance was measured by a transmission line technique, and the specific contact resistivity of $1.5{\times}10^{-6}\;{\Omega}\;cm^2$ is obtained for Co/Si/Co metal structures after a two-step annealing; at $550\;^{\circ}C$ for 10 min and $800\;^{\circ}C$ for 3min. The physical properties of the contacts were examined by using XRD and AES, and the results indicate that the Co-based metal contacts have better structural stability of silicide phases formed after the high temperature annealing.

• 한국재료학회지
• /
• 제11권2호
• /
• pp.71-75
• /
• 2001

The reaction stability of nickel with side-wall materials of SiO$_2$ and Si$_3$N$_4$ on p-type 4"(100) Si substrate were investigated. Ni on 1300 $\AA$ thick SiO$_2$ and 500 $\AA$ - thick Si$_3$N$_4$ were deposited. Then the samples were annealed at 400, 500, 750 and 100$0^{\circ}C$ for 30min, and the residual Ni layer was removed by a wet process. The interface reaction stability was probed by AES depth Profiling. No reaction was observed at the Ni/SiO$_2$ and Ni/Si$_3$N$_4$, interfaces at 400 and 50$0^{\circ}C$. At 75$0^{\circ}C$, no reaction occurred at Ni/SiO$_2$ interface, while $NiO_x$ and Si$_3$N$_4$ interdiffused at Ni/Si$_3$N$_4$ interface. At 100$0^{\circ}C$, Ni layers on SiO$_2$ and Si$_3$N$_4$ oxidized into $NiO_x$ and then $NiO_x$ interacted with side-wall materials. Once $NiO_x$ was formed, it was not removed in wet etching process and easily diffused into sidewall materials, which could lead to bridge effect of gate-source/drain.

• 전기전자학회논문지
• /
• 제25권3호
• /
• pp.467-472
• /
• 2021

고온에서도 반도체 소자의 안정적인 동작이 필요하다. 반도체 소자의 구조중에서 고온에서 불안정한 전기적 응답을 야기할 수 있는 영역은 금속과 반도체가 접합하는 콘택층이다. 본 연구에서는 p형 SiC 층위에 니켈-실리사이드(NiSix)의 콘택층을 형성하는 공정과정에 포함되는 어닐링 공정 조건이 콘택 저항의 비저항과 전체 저항에 미치는 효과를 고찰하였다. 이를 위해, 4인치 p형 SiC층 위에 전송길이 이론(transfer length method: TLM) 측정을 위한 알련의 전극 패턴들을 형성하였고, 어닐링 온도(1700와 1800℃)와 어닐링 시간(30와 60분)을 달리하여 4종의 시료를 제조하였으며, TLM을 이용한 저항을 측정하였다. 그 결과, 어닐링 조건이 콘택층의 저항과 소자의 전기적 안정성에 영향을 미치는 사실을 확인하였다.