• 대한금속재료학회지
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• 제50권12호
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• pp.939-948
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• 2012

A 3-ply clad metal consisting of aluminum and copper was fabricated by roll bonding process and the microstructures and mechanical properties of the roll-bonded and post-roll-bonding heat treated Cu/Al/Cu clad metal were investigated. A brittle interfacial reaction layer formed at the Cu/Al interfaces at and above $400^{\circ}C$. The thickness of the reaction layer increased from $12{\mu}m$ at $400^{\circ}C$ to $28{\mu}m$ at $500^{\circ}C$. The stress-strain curves demonstrated that the strength decreased and the ductility increased with heat treatment up to $400^{\circ}C$. The clad metal heat treated at $300^{\circ}C$ with no indication of a reaction layer exhibited an excellent combination of the strength and ductility and no delamination of layers up to final fracture in the tensile testing. Above $400^{\circ}C$, the ductility decreased rasxpidly with little change of strength, reflecting the brittle nature of the intermetallic interlayers. In Cu/Al/Cu clad heat treated above $400^{\circ}C$, periodic parallel cracks perpendicular to the stress axis were observed at the interfacial reaction layer. In-situ optical microscopic observation revealed that cracks were formed in the Cu layer due to the strain concentration in the vicinity of horizontal cracks in the intermetallic layer, promoting the premature fracture of Cu layer. Vertical cracks parallel to the stress axis were also formed at 15% strain at $500^{\circ}C$, leading to the delamination of the Cu and Al layers.

• 한국정밀공학회지
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• 제19권11호
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• pp.120-128
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• 2002

Interfacial cracks in a piezoelectric layer bonded to dissimilar elastic layers under the combined anti-plane mechanical shear and in-plane electrical leadings are considered. By using Fourier cosine transform, the mixed boundary value problem is reduced to a singular integral equation which is solved numerically to determine the stress intensity factors. Numerical results for the effects of the material properties and layer geometries on the stress intensity factors are obtained.

• 대한설비공학회지:설비저널
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• 제16권6호
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• pp.606-612
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• 1987

In this study, numerical model was developed to predict behavior of several layers in a solar pond and was solved by finite difference method. The empirical correlation that described heat and salt fluxes across interfacial boundary layer between mixed layer and diffusive layer in a solar pond were obtained from experiments and utilized in developing numerical model. As the results of this study, heat and salt fluxes across the interfacial boundary layer was found to depend on density ratio ${\beta}{\Delta}M_s/{\alpha}{\Delta}T.$ It was also found that the predicted value obtained by using the modified Weinberger's stability criteria showed a good agreement with experiment data.

• Membrane and Water Treatment
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• 제15권1호
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• pp.31-39
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• 2024

The flow in a nanopore of filtration membrane is often multiscale and consists of both the adsorbed layer flow and the intermediate continuum fluid flow. There is a controversy on which interface the slippage should occur in the nanopore filtration: On the adsorbed layer-pore wall interface or on the adsorbed layer-continuum fluid interface? What is the difference between these two slippage effects? We address these subjects in the present study by using the multiscale flow equations incorporating the slippage on different interfaces. Based on the limiting shear strength model for the slippage, it was found from the calculation results that for the hydrophobic pore wall the slippage surely occurs on the adsorbed layer-pore wall interface, however for the hydrophilic pore wall, the slippage can occur on either of the two interfaces, dependent on the competition between the interfacial shear strength on the adsorbed layer-pore wall interface and that on the adsorbed layer-continuum fluid interface. Since the slippage on the adsorbed layer-pore wall interface can be designed while that on the adsorbed layer-continuum fluid interface can not, the former slippage can result in the flux through the nanopore much higher than the latter slippage by designing a highly hydrophobic pore wall surface. The obtained results are of significant interest to the design and application of the interfacial slippage in nanoporous filtration membranes for both improving the flux and conserving the energy cost.

• 한국세라믹학회지
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• 제42권7호
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• pp.509-515
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• 2005

Interfacial reactions at LSGM electrolyte and NiO-GDC anode interfaces were thoroughly investigated with Environmental Scanning Electron Microscopy (ESEM-PHlLIPS XL-30) and Energy Dispersive X-ray (EDX-Link XL30). According to the analysis, serious reaction zone was observed at LSGM/NiO-GDC interface. It was found that the reaction layer was originated from the chemical reaction between NiO and LSGM. The reaction products were identified as La deficient form of LSGM based perovskite and Ni-La-O compounds such as LaSrGa$_{3}$O$_{7}$ and LaNiO$_{3}$ from the X-Ray Diffraction (XRD, Philips) analysis. According to the electrical characterization, interfacial layer was very electrically resistive which would be the cause of high internal resistance and low power generating characteristic of the unit cell.

• Membrane and Water Treatment
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• 제12권1호
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• pp.37-41
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• 2021

This paper presents the multiscale calculation results of the very fast volume transport in micro/nano cylindrical tubes with the wall slippage. There simultaneously occurs the adsorbed layer flow and the intermediate continuum fluid flow which are respectively on different scales. The modeled fluid is water and the tube wall is somewhat hydrophobic. The calculation shows that the power loss on the tube no more than 1.0 Watt/m can generate the wall slippage even if the fluid-tube wall interfacial shear strength is 1 MPa; The power loss on the scale 104 Watt/m produces the volume flow rate through the tube more than one hundred times higher than the classical hydrodynamic theory calculation even if the fluid-tube wall interfacial shear strength is 1 MPa. When the wall slippage occurs, the volume flow rate through the tube is in direct proportion to the power loss on the tube but in inverse proportion to the fluid-tube wall interfacial shear strength. For low interfacial shear strengths such as no more than 1 kPa, the transport in the tube appears very fast with the magnitude more than 4 orders higher than the classical calculation if the power loss on the tube is on the scale 104 Watt/m.

• The Korean Journal of Ceramics
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• 제1권1호
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• pp.7-12
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• 1995

When a $Ta_O_5$ dielectric film is deposited on a bare silicon, the growth of $SiO_2$ at the $Ta_O_5$/Si interface cannot be avoided. Even though the $SiO_2$ layer is ultrathin (a few nm), it has great effects on the electrical properties of the capacitor. The concentration depth profiles of the ultrathin interfacial $SiO_2$ and $SiO_2/Si_3N_4$ layers were obtained using an Auger electron spectroscopy (AES) equipped with a cylindrical mirror analyzer (CMA). These AES depth profiles were quantitatively analyzed by comparing with the theoretical depth profiles which were obtained by considering the inelastic mean free path of Auger electrons and the angular acceptance function of CMA. The direct measurement of the interfacial layer thicknesses by using a high resolution cross-sectional TEM confirmed the accuracy of the AES depth analysis. The $SiO_2/Si_3N_4$ double layers, which were not distinguishable from each other under the TEM observation, could be effectively analyzed by the AES depth profiling technique.

• 한국진공학회지
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• 제6권3호
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• pp.263-266
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• 1997

$In_{0.1}Ga_{0.9}As$/GaAs의 계면 특성을 상온에서 photoreflectance(PR) 측정을 통하여 연구 하였다. 에피층의 두께가 증가함에 따라 PR 신호에서 Franz-Keldysh oscillation(FKO)의 주 기가 감소하였고, 계면 전기장은 감소되었다. 이것은 InGaAs와 GaAs의 이종접합계면 부근 에서 격자부정합에 의한 결함이 증가되었기 때문으로 생각된다. 에피층의 두께가 300$\AA$보다 적은 경우 두께가 얇아짐에 따라 InGaAs층이 임계 두께에 가까워져 strain의 영향으로 밴 드갭 에너지가 크게 이동하였다.

• 한국주조공학회지
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• 제13권3호
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• pp.276-284
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• 1993

The interfacial phenomena between intermetallic compounds and Al matrix have been studied at $680^{\circ}C$ for various holding time under argon atmosphere. Model experiments were performed using Fe, Ni and Ti wire to observe the interfacial phenomena. The interfacial phenomena between intermetallic compounds and Al matrix were analysed by optical microscope, SEM and EDX. The results of EDX and XRD showed that the interfacial zones of intermetallic compounds/Al matrix were composed of several intermetallic layers. The reaction layer was varied with holding time and heating temperature. The investigation of interfacial zones in the specimen as a function of heat treatment time at $680^{\circ}C$ indicated that the best heat treatment condition for squeeze casting was $680^{\circ}C$ for 5min.

• Steel and Composite Structures
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• 제20권2호
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• pp.413-429
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• 2016

A theoretical method to predict the interfacial stresses in the adhesive layer of reinforced concrete beams strengthened with externally bonded carbon fiber-reinforced polymer (CFRP) plate is presented. The analysis provides efficient calculations for both shear and normal interfacial stresses in reinforced concrete beams strengthened with composite plates, and accounts for various effects of Poisson's ratio and Young's modulus of adhesive. Such interfacial stresses play a fundamental role in the mechanics of plated beams, because they can produce a sudden and premature failure. The analysis is based on equilibrium and deformations compatibility approach developed by Tounsi. In the present theoretical analysis, the adherend shear deformations are taken into account by assuming a parabolic shear stress through the thickness of both the reinforced concrete beam and bonded plate. The paper is concluded with a summary and recommendations for the design of the strengthened beam.