• 열처리공학회지
• /
• 제13권3호
• /
• pp.143-150
• /
• 2000

Ferritic plasma nitrocarburising was performed on pure iron using a modified DC plasma unit. This investigation was carried out with various gas compositions which consisted of nitrogen, hydrogen and carbon monoxide gases, and various gas pressures for 3 hours at $570^{\circ}C$. After treatment, the different cooling rates(slow cooling and fast cooling) were used to investigate its effect on the structure of the compound layer. The ${\varepsilon}$ phase occupied the outer part of the compound layer and ${\gamma}^{\prime}$ phase existed between the ${\varepsilon}$ phase and the diffusion zone. The gas composition of the atmosphere influenced the constitution of the compound layer produced, i.e. high nitrogen contents were essential for the production of ${\varepsilon}$ phase compound layer. It was found that with increasing carbon content in the gas mixture the compound layer thickness increased up to 10%. In the gas pressure around 3 mbar, the compound layer characteristics were slightly effected by gas pressure. However, in the low gas pressure and high gas pressure, the compound layer characteristics were significantly changed. The constitution of the compound layer was altered by varying the cooling rate. A large amount of ${\gamma}^{\prime}$ phase was transformed from the ${\varepsilon}$ phase during slow cooling.

• 접착 및 계면
• /
• 제12권4호
• /
• pp.144-150
• /
• 2011

폴리스티렌을 저수축제로 사용하고 Zn-stearate를 이형제로 사용하여 함량변화에 따라 벌크 몰드컴파운드의 표면형태 및 기계적 물성에 미치는 영향을 고찰하였다. XPS, 접촉각 측정기 등을 이용하여 표면과 깊이 방향에 대한 원소함량과 접촉각을 측정하였고, 표면형태는 FESEM을 이용하여 관찰하였으며, 표면조도 측정은 AFM을 이용하였다. 저수축제를 첨가하지 않은 경우에 비교하여 저수축제를 9.0 wt% 첨가하였을 경우에는 체적수축률은 0.35%에서 0.05%로 감소하였으며, 표면조도는 $0.27{\mu}m$에서 $0.12{\mu}m$로 감소하였다. 이형제의 함량을 1.8 wt%에서 3.6 wt%로 증가시켰을 경우에는 이형제가 주로 표면에 존재하고 표면조도를 증가시키는 것을 확인하였다. 저수축제의 함량을 5.0 wt%에서 9.0 wt%로 증가시킴에 따라 굴곡탄성율과 충격강도가 약 30% 감소하였다.

• 대한치과교정학회지
• /
• 제26권3호
• /
• pp.301-307
• /
• 1996

본 연구의 목적은 도재의 표면처리가 인장접착강도에 어떠한 영향을 미치는가를 알아보는 것이었다. 120개의 도재시편을 각 군당 10개씩 12군으로 나눈 후, 1군은 표면처리를 하지않았고, 2군에서 5군까지는 단독 표면처리를 6군에서 12군까지는 복합으로 표면처리를 시행하였으며 그후 교정용 레진으로 통상적인 방법에 따라 브라켓을 접착하고나서 각 군의 인장접착강도를 측정하여 다음과 같은 결론을 얻었다. 1. 모든 단독표면처리군(G2,G3,G4,G5)은 표면처리를 하지않은 군(G1)보다 인장접착강도가 통계적으로 유의성 있는 증가(P<0.05)를 나타내었으며, 단독표면처리군 중 샌드블라스팅군(G5)의 인장접착강도가 $10.34{\pm}2.50MPa$로 가장 높았다. 2. 복합표면처리군(G6,G7,G8,G9,G10,G11,G12)에서는 9-11.5MPa의 인장접착강도를 나타내었고 이들 상호간에는 통계적으로 유의차가 없었다. 3. 단독표면처리군 중 샌드볼라스팅군(G5)은 복합표면처리군(G6-G12)과 통계적으로 유의차가 없었다.

• 한국주조공학회지
• /
• 제31권2호
• /
• pp.66-70
• /
• 2011

Hot dip aluminizing (HDA) is widely used in industry for improving corrosion resistance of material. The formation of intermetallic compound layers during the contact between dissimilar materials at high temperature is common phenomenon. Generally, intermetallic compound layers of $Fe_2Al_5$ and $FeAl_3$ are formed at the Al alloy and Fe substrate interface. In case of cast iron, high contact angle of graphite existed in the matrix inhibits the formation of intermetallic compound layer, which carry with it the disadvantage of a reduced reaction area and mechanical properties. In present work, the process for the removal of graphite existed on the surface of specimen has been investigated. And also HDA was proceeded at $800^{\circ}C$ for 3 minutes in aluminum alloy melt. The efficiency of graphite removal was increased with the reduction of particle size in sanding process. Graphite appears to be present both in the region of melting followed by re-solidification and in the intermetallic compound layer, which could be attributed to the fact that the surface of cast iron is melted down by the formation of low melting point phase with the diffusion of Al and Si to the cast iron. Intermetallic compound layer consisted of $Fe(Al,Si)_3$ and $Fe_2Al_5Si$, the layer formed at cast iron side contained lower amount of Si.

• 한국재료학회:학술대회논문집
• /
• 한국재료학회 2010년도 춘계학술발표대회
• /
• pp.35.1-35.1
• /
• 2010

The Cu(In,Ga)Se2(CIGS) thin film solar cells have been achieved until almost 20% efficiency by NREL. These solar cells include chemically deposited CdS as buffer layer between CIGS absorber layer and ZnO window layer. Although CIGS solar cells with CdS buffer layer show excellent performance, many groups made hard efforts to overcome its disadvantages in terms of high absorption of short wavelength, Cd hazardous element. Among Cd-free candidate materials, the CIGS thin film solar cells with Zn compound buffer layer seem to be promising with 15.2%(module by showa shell K.K.), 18.6%(small area by NREL). However, few groups were successful to report high-efficiency CIGS solar cells with Zn compound buffer layer, compared to be known how to fabricate these solar cells. Each group's chemical bah deposition (CBD) condition is seriously different. It may mean that it is not fully understood to grow high quality Zn compound thin film on the CIGS using CBD. In this study, we focused to clarify growth mechanism of chemically deposited Zn compound thin film on the CIGS, especially. Additionally, we tried to characterize junction properties with unfavorable issues, that is, slow growth rate, imperfect film coverage and minimize these issues. Early works reported that film deposition rate increased with reagent concentration and film covered whole rough CIGS surface. But they did not mention well how film growth of zinc compound evolves homogeneously or heterogeneously and what kinds of defects exist within film that can cause low solar performance. We observed sufficient correlation between growth quality and concentration of NH3 as complex agent. When NH3 concentration increased, thickness of zinc compound increased with dominant heterogeneous growth for high quality film. But the large amounts of NH3 in the solution made many particles of zinc hydroxide due to hydroxide ions. The zinc hydroxides bonded weakly to the CIGS surface have been removed at rinsing after CBD.

• 한국재료학회지
• /
• 제11권12호
• /
• pp.1063-1067
• /
• 2001

The effect of the pulse parameters(pulse ratio and frequency) on the characteristics of the nitrided layer in the pulsed plasma nitrified SCM435 Steels was investigated. Material properties of the nitrided layer were analysed by employing optical microscope, scanning electron microscope(SEM), X-ray diffractometer(XRD) and micro-Vickers hardness tester. It was found that both the compound layer thickness and the surface hardness decreased with decreasing of pulse ratios. At high pulse ratio, the compound layer thickness and the surface hardness were rapidly decreased with decreasing frequency compared to lower pulse ratios.

• 한국표면공학회지
• /
• 제34권5호
• /
• pp.455-464
• /
• 2001

Effect of bombardment of the growing film by energetic particles on its properties is know over many years and is widely used for modification of the film properties. Despite of this there are no final answers on such questions as: what is the mechanism of compositional changes that take place for some compound films deposited under the ion bombardment, how the ion bombardment influences the epitaxial growth, what mechanisms govern the growth of the film on its early stages during deposition under the ion bombardment. The role of composition of film-forming species in formation of film structure is barely investigated or even not investigated at all. Experimental evidence and discussion of the influence of ion bombardment and composition of film-forming species on structure and composition of compound films are briefly considered in the review.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2002년도 춘계학술대회 논문집
• /
• pp.287-292
• /
• 2002

This paper presents a reverse engineering method for compound surfaces using vision system. A CNC machining center is used as a measuring station, which is equipped with slit beam generator and vision probe. Since obtained data using slit beam or laser scanner may have much data loss along the edge of compound surfaces, an algorithm is presented in this study to recover missing geometric data at such region. First, b-spline interpolation is applied to extract edge information of the surface, and as a next step, b-spline approximation is applied to recover the missing geometric data. Finally, b-spline skinning method is applied to regenerate the surface information. Appropriate simulation and experimental works are preformed to very the effectiveness of the proposed methods.

• 한국안광학회지
• /
• 제5권2호
• /
• pp.211-219
• /
• 2000

한국산(韓國産) 파리매아과(亞科)에 속하는 6속(屬) 6종(種)의 복안표면 미세구조를 주사전자현미경과 화상분석시스템을 이용하여 형태학적으로 연구하였다. 개안의 형태는 다양하게 나타났으나, 공통적으로 개안표면직경은 부분에 따라 차이를 보여 내측, 중간부, 외측이 구분되었다. 검정파리매(Trichomachimus scutellaris(Coquillett))에서는 전체적인 개안표면에서 특징적인 미세구조가 관찰되었으며 다른 종과는 형태적인 차이를 보여 종(種) 수준의 분류에 유용하였다.

• 한국표면공학회지
• /
• 제35권1호
• /
• pp.47-52
• /
• 2002

Intermetallic compound on the soldered interface plays important role on the bondability and mechanical properties of soldered joint. The formation of intermetallic compounds are influenced by many factors such as temperature, holding time, base metals and so on. On this study the effect of number of reflow times on the intermetallic growth was investigated. For the experimental materials, Sn-3.5Ag-0.7Cu solder ball of 0.3mm diameter and RMA-type flux were used. Thickness of intermetallic compound of solder ball by 2nd reflow showed nearly 60% higher than that of 1st reflow, and shear strength showed 10% higher value. Thickness and shear strength according to the position of interface such as upper side or lower side between two substrates were also investigated.