• Title/Summary/Keyword: Substrate angle

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Effect of Dewpoints on Annealing Behavior and Coating Characteristics in IF High Strength Steels Containing Si and Mn (Si, Mn함유 IF 고강도강의 소둔거동 및 도금특성에 미치는 이슬점 온도의 영향)

  • Jeon, Sun-Ho;Shin, Kwang-Soo;Sohn, Ho-Sang;Kim, Dai-Ryong
    • Korean Journal of Metals and Materials
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    • v.46 no.7
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    • pp.427-436
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    • 2008
  • The effect of dewpoints on annealing behavior and coating characteristics such as wettability and galvannealing kinetics was studied by annealing 0.3wt%Si - 0.1~0.4wt% Mn added interstitial-free high strength steels(IF-HSS). The 0.3wt%Si-0.1wt%Mn steel exhibited good wettability with molten zinc and galvannealing kinetics after annealing when the dewpoint of $H_2-N_2$ mixed gas was above $-20^{\circ}C$. It is shown that the wettability and galvannealing kinetics are directly related to the coverage of the external(surface) oxide formed by selective oxidation during annealing. At $N_2-15%H_2$ annealing atmosphere, the increase of dewpoint results in a gradual transition from external to internal selective oxidation. The decrease of external oxidation of alloying elements with a concurrent increase of their subsurface enrichment in the substrate, showing a larger surface area that was free of oxide particles, contributed to the improved wettability and galvannealing kinetics. On the other hand, the corresponding wettability and galvannealing kinetics were deteriorated with the dewpoints below $-20^{\circ}C$. The continuous oxide layer of network and/or film type was formed on the steel surface, leading to the poor wettability and galvannealing kinetics. It causes a high contact angle between annealed surface and molten zinc and plays an interrupting role in interdiffusion of Zn and Fe during galvannealing process.

Numerical and experimental investigation for monitoring and prediction of performance in the soft actuator

  • Azizkhani, Mohammadbagher;sangsefidi, Alireza;Kadkhodapour, Javad;Anaraki, Ali Pourkamali
    • Structural Engineering and Mechanics
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    • v.77 no.2
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    • pp.167-177
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    • 2021
  • Due to various benefits such as unlimited degrees of freedom, environment adaptability, and safety for humans, engineers have used soft materials with hyperelastic behavior in various industrial, medical, rescue, and other sectors. One of the applications of these materials in the fabrication of bending soft actuators (SA) is that they have eliminated many problems in the actuators such as production cost, mechanical complexity, and design algorithm. However, SA has complexities, such as predicting and monitoring behavior despite the many benefits. The first part of this paper deals with the prediction of SA behavior through mathematical models such as Ogden and Darijani, and its comparison with the results of experiments. At first, by examining different geometric models, the cubic structure was selected as the optimal structure in the investigated models. This geometrical structure at the same pressure showed the most significant bending in the simulation. The simulation results were then compared with experimental, and the final gripper model was designed and manufactured using a 3D printer with silicone rubber as for the polymer part. This geometrical structure is capable of bending up to a 90-degree angle at 70 kPa in less than 2 seconds. The second section is dedicated to monitoring the bending behavior created by the strain sensors with different sensitivity and stretchability. In the fabrication of the sensors, silicon is used as a soft material with hyperelastic behavior and carbon fiber as a conductive material in the soft material substrate. The SA designed in this paper is capable of deforming up to 1000 cycles without changing its characteristics and capable of moving objects weigh up to 1200 g. This SA has the capability of being used in soft robots and artificial hand making for high-speed objects harvesting.

Investigation of the Influence of Radius and Corner Position on the Residual Stress Distribution in the Vicinity of the Repaired Region via Directed Energy Deposition by using Finite Element Analysis (유한 요소 해석을 이용한 DED 공정의 코너 반경 및 위치에 따른 보수 영역 부근 잔류응력 분포 영향성 조사)

  • Alissultan, Aliyev;Lee, Kwang-Kyu;Ahn, Dong-Gyu
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.20 no.7
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    • pp.33-40
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    • 2021
  • Current industrial flow is directed toward reducing the usage of raw materials by reusing parts, which is referred to as a circular economy (CE). Repair is one of the most value-added approaches in CE, which can be efficiently accomplished via additive manufacturing. The repair technology of metallic parts via the directed energy deposition process, which includes the selective removal and redeposition of damaged regions of metallic parts. Residual stress characteristics depend on the shape of the part and the shape of the redeposition region. The objective of this study is to investigate the effects of the radius and corner position of the substrate on the residual stresses for repair by using finite element analysis (FEA). The residual stress distribution of the 45° angle groove at the edge of the circular shape models on the outer and inner radii was analytically investigated. The analysis was accomplished using SYSWELD software by applying a moving heat source with defined material properties and cooling conditions integrated into the FEA model. The results showed a similar pattern of concentrated stress distribution for all models except the 40-mm and 60-mm radii, for which the maximum stress locations were different. The maximum residual stresses are high but lower than the yield strength, suggesting the absence of cracks and fractures due to residual stresses.

The physical properties of several HTS coated conductors

  • Lee, Nam-Jin;Oh, Sang-Soo;Song, Kyu-Jeong;Ha, Dong-Woo;Kim, Ho-Sup;Ha, Hong-Soo;Ko, Rock-Kil;Kim, Tae-Hyung;Kim, Sang-Cheol;Yu, Kwon-Kuk;Moon, Seung-Hyun;Youm, Do-Jun
    • Progress in Superconductivity and Cryogenics
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    • v.9 no.4
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    • pp.19-23
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    • 2007
  • The superconducting properties of several HTS coated conductors (CC), which had different tape structures, fabricated by KERI, X and Y institutes were compared. We have fabricated the $high-J_c$ SmBCO CC, which has 273.5 A/cm, $1.2MA/cm^2$ and 93.5 K for $I_C,\;J_C\;and\;T_{c-zero}$, respectively, using the EDDC (Evaporation using Drum in Dual Chambers) process. Both X and Y institutes CCs, however, were purchased. The n-values of KERI, X and Y institutes CCs are 58.5, 40.7 and 31.5 in $V=1{\sim}10{\mu}V$ criterion, respectively. The in-field properties of $I_C$ at 77K were investigated and the $J_C(B)/J_C(0G)$ at 0.5 T with $B{\perp}$ ab-plane are 0.31, 0.19 and 0.24 for KERI, X and Y institutes CCs, respectively. From the $I_C-{\theta}-B$ measurement, we observed that the ab-plane of ReBCO phase was tilted for the ab-plane of substrate in the KERI and X institutes CCs. The tilted angle is about 5 degree. We confirmed that the peak shift (as an inclined texture) was observed by X-ray (102) pole figures of the SmBCO for the KERI CC.

Liquid Crystal Orientation on LaGaO Thin Films Induced by a Brush Coating Process (브러시 코팅 공정에 의해 유도된 LaGaO 박막의 액정 배향)

  • Byeong-Yun Oh
    • Journal of IKEEE
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    • v.28 no.3
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    • pp.261-270
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    • 2024
  • In this study, a lanthanum gallium oxide (LaGaO) solution was prepared using a sol-gel method. By simply forming a LaGaO thin film through adjusting the curing temperature after applying the solution onto the substrate using a brush coating process, the potential for use as a liquid crystal (LC) alignment film in the LC display industry was validated. Through optical microscope observation, it was confirmed that the LC molecules were uniformly aligned as the curing temperature of the LaGaO thin film increased. It was confirmed that the LaGaO thin film cured at 230℃ had low pretilt angle, and that LaGaO particles were formed in a single direction as observed through an atomic force microscope. Through X-ray photoelectron spectroscopy, it was found that the LaGaO metal oxide thin film was well formed. Finally, it has been confirmed that LaGaO metal oxide has the potential as a novel LC alignment film material, as it exhibits excellent electrical and optical properties, along with high optical transmittance.

Temperature Analysis for the Point-Cell Source in the Vapor Deposition Process

  • Park, Jong-Wook;Kim, Sung-Cho;Hun Jung
    • Journal of Mechanical Science and Technology
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    • v.18 no.9
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    • pp.1680-1688
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    • 2004
  • The information indicating device plays an important part in the information times. Recently, the classical CRT (Cathod Ray Tube) display is getting transferred to the LCD (Liquid Crystal Display) one which is a kind of the FPDs (Flat Panel Displays). The OLED (Organic Light Emitting Diodes) display of the FPDs has many advantages for the low power consumption, the luminescence in itself, the light weight, the thin thickness, the wide view angle, the fast response and so on as compared with the LCD one. The OLED has lately attracted considerable attention as the next generation device for the information indicators. And also it has already been applied for the outside panel of a mobile phone, and its demand will be gradually increased in the various fields. It is manufactured by the vapor deposition method in the vacuum state, and the uniformity of thin film on the substrate depends on the temperature distribution in the point-cell source. This paper describes the basic concepts that are obtained to design the point-cell source using the computational temperature analysis. The grids are generated using the module of AUTOHEXA in the ICEM CFD program and the temperature distributions are numerically obtained using the STAR-CD program. The temperature profiles are calculated for four cases, i.e., the charge rate for the source in the crucible, the ratio of diameter to height of the crucible, the ratio of interval to height of the heating bands, and the geometry modification for the basic crucible. As a result, the blowout phenomenon can be shown when the charge rate for the source increases. The temperature variation in the radial direction is decreased as the ratio of diameter to height is decreased and it is suggested that the thin film thickness can be uniformed. In case of using one heating band, the blowout can be shown as the higher temperature distribution in the center part of the source, and the clogging can appear in the top end of the crucible in the lower temperature. The phenomena of both the blowout and the clogging in the modified crucible with the nozzle-diffuser can be prevented because the temperature in the upper part of the crucible is higher than that of other parts and the temperature variation in the radial direction becomes small.

Effects of Interface Soaking on Strain Modulation in InAs/GaSb Strained-Layer Superlattices (계면 흡착에 의한 InAs/GaSb 초격자의 응력변조 효과)

  • Shin, H.W.;Choe, J.W.;Kim, J.O.;Lee, S.J.;Kim, C.S.;Noh, S.K.
    • Journal of the Korean Vacuum Society
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    • v.20 no.1
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    • pp.35-41
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    • 2011
  • In this study, the interface soaking effect in InAs/GaAs strained-layer superlattice (SLS) on crystalline phase modulation has been analyzed by the x-ray diffraction (XRD) curve. The strain variation induced by As and/or Sb soaking was determined by the separation angle between the substrate peak and the 0th-order superlattice satellite peak in the XRD spectra. Contrated that the As/InAs soaking arises minor GaAs-like interfacial layer, the Sb/GaSb soaking induces InSb-like one. The Fourier-transformed curves of the Pendellosung interference oscillation shows that the optimum soaking times of As/InAs and Sb/GaSb are 2 sec and 12 sec, at which the highest crystallineity has, respectively. An anomalous twin-peak phenomenon that a satellite peak splits into two peaks was observed in the SLS structure co-soaked by As and Sb at InAs${\rightarrow}$GaSb interfaces. We suggest that it may be resulted from coexistence of two kinds crystalline phases of InAsSb and GaAsSb due to intermixing of In${\leftrightarrow}$Ga and Sb${\leftrightarrow}$As.

Formation of Passivation Layer and Its Effect on the Defect Generation during Trench Etching (트렌티 식각시 식각 방지막의 형성과 이들이 결함 생성에 미치는 영향)

  • Lee, Ju-Wook;Kim, Sang-Gi;Kim, Jong-Dae;Koo, Jin-Gon;Lee, Jeong-Yong;Nam, Kee-Soo
    • Korean Journal of Materials Research
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    • v.8 no.7
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    • pp.634-640
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    • 1998
  • A well- shaped trench was investigated in view of the defect distribution along trench sidewall and bottom using high resolution transmission electron microscopy. The trench was formed by HBr plasma and additive gases in magnetically enhanced reactive ion etching system. Adding $0_2$ and other additive gases into HBr plasma makes it possible to eliminate sidewall undercut and lower surface roughness by forming the passivation layer of lateral etching, resulted in the well filled trench with oxide and polysilicon by subsequent deposition. The passivation layer of lateral etching was mainly composed of $SiO_xF_y$ $SiO_xBr_y$ confirmed by chemical analysis. It also affects the generation and distribution of lattice defects. Most of etch induced defects were found in the edge region of the trench bottom within the depth of 10$\AA$. They are generally decreased with the thickness of residue layer and almost disappeared below the uni¬formly thick residue layer. While the formation of crystalline defects in silicon substrate mainly depends on the incident angle and energy of etch species, the region of surface defects on the thickness of residue layer formed during trench etching.

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Flexible Durability of Ultra-Thin FPCB (초박형 FPCB의 유연 내구성 연구)

  • Jung, Hoon-Sun;Eun, Kyoungtae;Lee, Eun-Kyung;Jung, Ki-Young;Choi, Sung-Hoon;Choa, Sung-Hoon
    • Journal of the Microelectronics and Packaging Society
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    • v.21 no.4
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    • pp.69-76
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    • 2014
  • In this study, we developed an ultra-thin flexible printed circuit board(FPCB) using the sputtered flexible copper clad laminate. In order to enhance the adhesion between copper and polyimide substrate, a NiMoNb addition layer was applied. The mechanical durability and flexibility of the ultra-thin FPCB were characterized by stretching, twisting, bending fatigue test, and peel test. The stretching test reveals that the ultra-thin FPCB can be stretched up to 7% without failure. The twisting test shows that the ultra-thin FPCB can withstand an angle of up to $120^{\circ}$. In addition, the bending fatigue test shows that the FPCB can withstand 10,000 bending cycles. Numerical analysis of the stress and strain during stretching indicates the strain and the maximum von Mises stress of the ultra-thin FPCB are comparable to those of the conventional FPCB. Even though the ultra-thin FPCB shows slightly lower durability than the conventional FPCB, the ultra-thin FPCB has enough durability and robustness to apply in industry.

Cell Patterning on Various Substrates Using Polyelectrolyte Multilayer and Microstructure of Poly(Ethylene Glycol) (다양한 기판 위에서 고분자 전해질 다층 막과 폴리에틸렌글리콜 미세 구조물을 이용한 세포 패터닝 방법)

  • Shim, Hyun-Woo;Lee, Ji-Hye;Choi, Ho-Suk;Lee, Chang-Soo
    • Korean Chemical Engineering Research
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    • v.46 no.6
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    • pp.1100-1106
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    • 2008
  • In this study, we presented rapid and simple fabrication method of functionalized surface on various substrates as a universal platform for the selective immobilization of cells. The functionalized surface was achieved by using deposition of polyelectrolyte such as poly(allyamine hydrochloride) (PAH), poly(diallyldimethyl ammonium chloride) (PDAC), poly(4-ammonium styrene sulfonic acid) (PSS), poly(acrylic acid) (PAA) and fabrication of poly(ethylene glycol) (PEG) microstructure through micro-molding in capillaries (MIMIC) technique on each glass, poly(methyl methacrylate) (PMMA), polystyrene (PS) and poly(dimethyl siloxane) (PDMS) substrate. The polyelectrolyte multilayer provides adhesion force via strong electrostatic attraction between cell and surface. On the other hand, PEG microstructures also lead to prevent non-specific binding of cells because of physical and biological barrier. The characteristic of each modified surface was examined by using static contact angle measurement. The modified surface onto several substrates provides appropriate environment for cellular adhesion, which is essential technology for cell patterning with high yield and viability in the micropatterning technology. The proposed method is reproducible, convenient and rapid. In addition, the fabrication process is environmentally friendly process due to the no use of harsh solvent. It can be applied to the fabrication of biological sensor, biomolecules patterning, microelectronics devices, screening system, and study of cell-surface interaction.