기술해설 및 Q&A : 고압 또는 고압,고온 조건에서의 부식 시험 방법

허주열 ( Joo Youl Huh ) 한국부식방식학회 2009 부식과 방식 Vol.8 No.1

연구논문 - 박막 및 전자재료 - : 정합계의 열역학 및 상평형 특성

허주열 ( Joo Youl Huh ) 대한금속재료학회 ( 구 대한금속학회 ) 1996 재료.물성 심포지엄 Vol.- No.-

근접승화법을 이용한 CdTe박막의 성장에 관한 연구

이민석,허주열,김동환,Lee, Min-Suk,Huh, Joo-Youl,Kim, Dong-Hwan 한국재료학회 1998 한국재료학회지 Vol.8 No.5

Cadmium telluride films were grown by close-spaced sublimation(CSS) technique. The effects of various deposition parameters such as ambient pressure, source- to-substrate spacings and temperatures on the growth rate and the microstructure were investigated. The growth mode of CdTe films showed a transition as the ambient pressure changed. This transition was interpreted in terms of the diffusion limited transport and the sublimation limited transport of Cd and $Te_2$ vapors. Experimental results indicated that the transition of growth mode was related with the mean free path of gas molecules. The growth rate and the microstructure of CdTe films were affected by the source type- bulk or powder. This change was due to the temperature difference at the source surface. XRD and SEM analysis showed that the growth rate was one of the main factors to determine CdTe microstructures. 고효율 박막형 태양전지 제조를 위해 근접승화법에 의한 CdTe박막의 성장을 연구하였다. 내부압력의 변화, 기판과 소스 사이의 거리, 기판과 소스의 온도 등의 변수가 성장속도와 미세구조에 미치는 영향을 관찰했다. 내부압력의 변화에 따라 성장과정이 diffusion limited transport와 sublimation limited transport로 나뉘어지며, 이 두가지 성장방식의 분기점은 기체분자의 평균자유행정거리에 의해 결정되었다. 소스의 형태에 따라서 박막의 성장속도와 미세구조는 큰 차이를 보였으며, 실험을 통해 이러한 차이가 증발표면의 온도강하에 의한 현상임을 규명하였다. 기판과 소스사이의 간격에 따른 성장속도를 해석하기 위해 일방향열해석을 통해 기판과 소스표면의 온도를 계산하였다. X선 회절분석과 표면형상의 관찰을 통해 성장속도가 박막의 미세구조에 영향을 줌을 알았다. 기판의 온도가 증가하면서 박막성장시 (111)로의 우선성장방위가 관찰되었지만 고온이 되면서 다시 random orientation의 경향을 나타냈다.

590 MPa TRIP강의 선택적 표면산화 거동과 표면 산화막이 도금특성에 미치는 영향

김성환 ( Seong Hwan Kim ),임준모 ( Jun Mo Im ),허주열 ( Joo Youl Huh ),이석규 ( Suk Kyu Lee ),박노범 ( Rho Bum Park ),김종상 ( Jong Sang Kim ) 대한금속재료학회(구 대한금속학회) 2011 대한금속·재료학회지 Vol.49 No.4

In order to gain better understanding of the selective surface oxidation and its influence on the galvanizability of a transformation-induced plasticity (TRIP) assisted steel containing 1.5 wt.% Si and 1.6 wt.% Mn, a model experiment has been carried out by depositing Si and Mn (each with a nominal thickness of 10 nm) in either monolayers or bilayers on a low-alloy interstitial-free (IF) steel sheet. After intercritical annealing at 800℃ in a N2 ambient with a dew point of -40℃, the surface scale formed on 590 MPa TRIP steel exhibited a microstructure similar to that of the scale formed on the Mn/Si bilayer-coated IF steel, consisting of Mn2SiO4 particles embedded in an amorphous SiO2 film. The present study results indicated that, during the intercritical annealing process of 590 MPa TRIP steel, surface segregation of Si occurs first to form an amorphous SiO2 film, which in turn accelerates the out-diffusion of Mn to form more stable Mn-Si oxide particles on the steel surface. During hot-dip galvanizing, particulate Fe3O4, MnO, and Si-Mn oxides were reduced more readily by Al in a Zn bath than the amorphous SiO2 film. Therefore, in order to improve the galvanizability of 590 TRIP steel, it is most desirable to minimize the surface segregation of Si during the intercritical annealing process.

팔라듐 표면처리를 통한 Massive Spalling 현상의 억제

이대현 ( Dae Hyun Lee ),정보묵 ( Bo Mook Chung ),허주열 ( Joo Youl Huh ) 대한금속재료학회 ( 구 대한금속학회 ) 2010 대한금속·재료학회지 Vol.48 No.11

The reactions between a Sn-3.0Ag-0.5Cu solder alloy and electroless Ni/electroless Pd/immersion Au (ENEPIG) surface finishes with various Pd layer thicknesses (0, 0.05, 0.1, 0.2, 0.4 μm) were examined for the effect of the Pd layer on the massive spalling of the (Cu,Ni)6Sn5 layer during reflow at 235℃. The thin layer deposition of an electroless Pd (EP) between the electroless Ni (7 μm) and immersion Au (0.06 μm) plating on the Cu substrate significantly retarded the massive spalling of the (Cu,Ni)6Sn5 layer during reflow. Its retarding effect increased with an increasing EP layer thickness. When the EP layer was thin (≤0.1 μm), the retardation of the massive spalling was attributed to a reduced growth rate of the (Cu,Ni)6Sn5 layer and thus to a lowered consumption rate of Cu in the bulk solder during reflow. However, when the EP layer was thick (≥0.2 μm), the initially dissolved Pd atoms in the molten solder resettled as (Pd,Ni)Sn4 precipitates near the solder/(Cu,Ni)6Sn5 interface with an increasing reflow time. Since the Pd resettlement requires a continuous Ni supply across the (Cu,Ni)6Sn5 layer from the Ni(P) substrate, it suppressed the formation of (Ni,Cu)3Sn4 at the (Cu,Ni)6Sn5/Ni(P) interface and retarded the massive spalling of the (Cu,Ni)6Sn5 layer.

리플로우 솔더링시 솔더/Cu 계면반응속도에 미치는 Cu- 첨가 솔더의 영향

허주열,강대웅 대한금속재료학회(대한금속학회) 2000 대한금속·재료학회지 Vol.38 No.1

We have investigated the effects of Cu additions to pure Sn and eutectic Sn-Pb solders on the morphology and growth kinetics of the intermetatllics (Cu_6Sn_5) and on the consumption rate of Cu substrate during isothermal reflow soldering. The consumption rate of Cu substrate could be reduced with increasing Cu content in both Sn and Sn-Pb solders up to the respective solubilities at reflow temperatures. The effect of Cu addition was more significant for the Sn solder which had a higher Cu solubility. The Cu addition also resulted in morphological changes of the intermetallic layer. With increasing Cu content, the interface between Cu_6Sn_5 layer and solder roughened for pure Sn solder whereas it flattened fur the eutectic Sn-Pb solder. When the time(t) dependence of the intermatallic layer thickness(X￣) was modelled as X￣ = a×t^n, the growth constant a appeared to increase with the Cu content whereas the growth exponent n decreased. It was shown that the growth kinetics of the intermetallic layer could be well interpreted by a model of grain boundary diffusion controlled growth.

비정질 Cu-Ag-Ce 합금과 Sn 솔더의 계면반응

이성욱,허주열 대한금속재료학회(대한금속학회) 1999 대한금속·재료학회지 Vol.37 No.6

The interfacial reaction behavior between the melt-spun, amorphous 54.8 at% Cu-39.6 at% Ag-5.6 at% Ce alloy and the pure Sn solder was investigated at 240℃ and 180℃ and was compared with that between the crystalline alloy obtained by a crystallization treatment of the amorphous alloy and the Sn solder. The amorphous and crystalline alloys showed no qualitative difference in reaction behavior at 240℃. The reaction zone with a layered structure of Cu_6Sn_5/Ce_5Sn₃/Cu_6Sn_5+Sn(l)/(Cu-Ce)+Sn(l) grew fast as the liquid Sn dissolved preferentially Ag of the alloys. During the annealing of the Sn-wetted alloys at 180℃ for 100 hours, the reaction zones formed in the amorphous and crystalline alloys showed similar layered structures but the growth behavior of the reaction zone was significantly different: a reaction-limited growth in the amorphous alloy and a diffusion-limited growth in the crystalline growth. The difference can be at-tributed to the fact that the bulk diffusivity of Sn in the amorphous alloy is much lower than the grain boundary diffusivity of Sn in the crystalline alloy.

Zr-1.0Nb 합금의 부식 및 기계적 특성에 미치는 최종열처리의 영향

정용환,허주열,박정용,하승원 대한금속재료학회(대한금속학회) 2001 대한금속·재료학회지 Vol.39 No.10

The corrosion behavior and mechanical properties were investigated for Zr-1.0Nb alloys which were prepared by vacuum arc remelting and received different final heat-treatments. Corrosion tests were carried out in a static autoclave containing aqueous solution of 360℃ water and 360℃ LiOH (70 ppm). Microstructures of the tested alloys were analyzed using optical microscopy and TEM, and the cross-sectional surface of oxide layer was analyzed using SEM. All of the tested alloys showed higher corrosion rates in the 360℃ aqueous LiOH solution than in 360℃ water. As for the corrosion behavior in the 360℃ aqueous LiOH solution, the alloys exhibited a transition in corrosion rate as early as 30-45 days exposure. With respect to final annealing temperature, Zr-1.0Nb alloy having partialy recrystallized structure in this study showed higher corrosion resistance compared with the alloys having stress relieved, or fully recrystallized structure. It was concluded from TEM study that corrosion behavior would be related to the distribution and size of second phase particles. The yield strength, ultimate tensile strength and hardness decreased as the final annealing temperature increased.

TiNi 형상기억합금에서 항온열처리가 변태 및 기계적 성질에 미치는 영향

김상주,허주열 대한금속재료학회(대한금속학회) 1985 대한금속·재료학회지 Vol.23 No.9

There are many problems to be solved for more wide practical applications of near-equiatomic TiNi shape memory alloys. In this point of view, a study has been made of the effect of isothermal heat treatment in the temperature range of 450℃ to 750℃ on the transition temperatures, especially M_s and A_f, and on the mechanical properties and the effect of thermal cycling on the electric resistivity curve. For this investigation, a Ti-rich TiNi shape memory alloy containing 52.36 at.% Ti was prepared. Thermal cycling caused the electric resistivity peak and the decrease of M_s. but did not affect T_R, the temperature at which electric resistivity started increasing. Both M_s and A_f increased with the temperature of isothermal heat-treatment above 450℃. when the increasing rate of M_s was higher than that of A_f. Elongation and tensile strength were highly increased by long-time (100 hr) isothermal heat-treatment and these were dependent on the holding time rather than the temperature. There also existed the variation in the fracture mode about 550℃.