• Transactions of Materials Processing
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• v.16 no.2 s.92
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• pp.138-143
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• 2007

Superplastic forming/diffusion bonding (SPF/DB) processes were analyzed using a 3-D rigid visco-plastic finite element method. A constant-triangular element based on membrane approximation and an incremental theory of plasticity are employed for the formulation. The coulomb friction law is used for interface friction between tool and material. Pressure-time relationship for a given optimal strain rate is calculated by stress and pressure values at the previous iteration step. In order to improve the contact searching, hierarchical search algorithm has been applied and implemented into the code. Various geometries including sandwich panel and 3 sheet shape for 3-D SPF/DB model are analyzed using the developed program. The validity fer the analysis is verified by comparison between analysis and results in the literature.

• Journal of the Korean Chemical Society
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• v.36 no.5
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• pp.627-631
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• 1992

A simple one dimensional model was proposed to describe a hydrogen bonding in crystals, which was based on the Lippincott's empirical potential. The model was used to calculate internal stretching vibrational frequencies of $NH_4I$ crystal at high pressures. The calculated results were in agreement with Raman experimental results qualitatively. At relatively lower high pressures, as pressure increases internal stretching vibrational frequencies shift lower due to increase of the hydrogen bonding effect. At higher pressures, the frequencies shift higher due to the repulsive contribution of interatomic potential induced by the reduction of interatomic distance as pressure increases.

• Transactions of Materials Processing
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• v.31 no.6
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• pp.337-343
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• 2022

Electrically assisted pressure joining (EAPJ) utilizes electric current-induced kinetic enhancement to achieve solid state diffusion bonding within a short time. In this study, aluminum alloy specimens, which are known as a hard-to-weld metal, were successfully solid-state joined through EAPJ. The bonding process was performed in two ways: continuous direct current (CDC), which applies relatively low current density, and pulsed direct current (PDC), which applies high current density. It was observed that the bonding strength was higher in PDC than in CDC. The microstructure of the joint was characterized using 3D X-ray microscopy (XRM) and electron backscatter diffraction (EBSD).

• Proceedings of the KIEE Conference
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• 2002.07c
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• pp.2020-2022
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• 2002

SiC direct bonding technology is very attractive for both SiCOI(SiC-on-insulator) electric devices and SiC-MEMS fileds because of its application possibility in harsh environements. This paper presents on pre-bonding according to HF pre-treatment conditions in SiC wafer direct bonding using PECVD oxide. The PECVD oxide was characterized by XPS and AFM, respectively. The characteristics of bonded sample were measured under different bonding conditions of HF concentration and applied pressure, respectively. The bonding strength was evaluated by tensile strength method. Components existed in the interlayer were analyzed by using FT-IR. The bond strength depends on the HF pre-treatment condition before pre-bonding (Min : 5.3 kgf/$cm^2{\sim}$ Max : 15.5 kgf/$cm^2$).

• Proceedings of the KWS Conference
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• 2006.05a
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• pp.233-235
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• 2006

This study was performed to find the best bonding conditions by comparing mechanical properties in solar collector. The solar collector that consists of copper plate and tube was successfully bonding by ultrasonic seam welding. In this experiment, we varied the values of welding pressure and welding amplitude and fixed the values of speed and frequency. Consequently, it was find that the welding pressure had higher effort on bonding strength than the welding amplitude.

• Restorative Dentistry and Endodontics
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• v.29 no.4
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• pp.339-345
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• 2004

The aim of this study was to measure and compare the micro shear bond strengths of the following dentin bonding systems to the dentin surfaces under simulated pulpal pressure: All Bond $2^{\circledR},{\;}Second^{\circledR},{\;}AdheSE^{\circledR}$, Adper Prompt $L-Pop^{\circledR}$. The occlusal surfaces of 180 extracted human molars were prepared so the dentin bonding surfaces could be exposed. The teeth were randomly assigned to 3 equal groups of 60 each and subdivided. The dentin surfaces were treated with the above mentioned bonding system and resin composite cylinders were built up under a simulated pulpal pressure when saline (Group II) or diluted bovine serum (Group III) was used as the pulpal fluid. As a control. the same procedures were performed in the dried dentin surfaces (Group I). After one day of storage in water. the micro shear bond strengths were measured using an EZ tester. Group II and III showed significantly lower shear bond strength than Group I statistically (p < 0.05). $SEbond^{\circledR}{\;}and{\;}AdheSE^{\circledR}$ showed no difference among the different dentin condition. In the Adper Prompt $L-Pop^{\circledR}$. a simulated pulpal pressure were applied to the specimens using diluted bovine serum. which showed a higher strength than the specimens in which saline was used (p < 0.05).

• Composites Research
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• v.24 no.5
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• pp.23-28
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• 2011

In this paper, the bonding strengths of co-cured T800 carbon/epoxy composite-aluminum single lap joints with and without additional pressures were investigated using the pressure information induced by the fiber tension during a filament winding process. The specimens of all the tests were fabricated by an autoclave vacuum bag de-gassing molding being controlled forming pressures (absolute pressures of 0.1MPa, 0.3MPa and 0.7MPa including vacuum). A special device which can act uniform additional pressures on the joining part of the single lap joint specimen was designed to measure the bonding strengths of composite-aluminum liners of type III hydrogen pressure vessel fabricated by a filament winding process. After the three different additional pressures (absolute pressures of 0.1MPa, 0.3MPa and 0.7MPa) were applied to the specimens the effect of the additional pressures on the bonding strengths of the co-cured single-lap joints were evaluated.

• Journal of Welding and Joining
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• v.18 no.1
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• pp.70-76
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• 2000

A rolled steel for structural parts and lead bronze alloy were bonded each other by a new semi-solid diffusion bonding process to investigate the effect of the process parameters, for example bonding temperature and bonding time, on the interface characteristics, and bonding behavior. It can be possible that manufacture of the bonded steel/lead bronze which has a cylindrical shape with inserted the lead bronze alloy into the steel ring by the diffusion bonding process under the semi-solid condition of the lead bronze alloy without any pressure and flux. It has been know that the control of the amount of the liquid phase in semi-solid lead bronze alloy was very important to obtain soundness interface, since the shear strength of the bonded steel/lead bronze at 850℃ for 60 minutes under the condition of about 40% of the liquid phase in the lead bronze alloy shows maximum value, 210 MPa. The shear strength increases with an increase in bonding time and show maximum value, and then decreases.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.447-450
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• 2001

Abstract-Si direct bonding(SDB) technology is very attractive for both Si-on-insulator(SOI) electric devices and MEMS applications because of its stress free structure and stability. This paper presents on pre-bonding according to HF pre-treatment conditions in Si wafer direct bonding. The characteristics of bonded sample were measured under different bonding conditions of HF concentration, and applied pressure. The bonding strength was evaluated by tensile strength method. The bonded interface and the void were analyzed by using SEM and IR camera, respectively. Components existed in the interlayer were analysed by using FT-lR. The bond strength depends on the HF pre-treatment condition before pre-bonding (Min : 2.4kgf/cm$^2$∼Max : 14.9kgf/cm$^2$).

• Journal of the Semiconductor & Display Technology
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• v.10 no.2
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• pp.103-108
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• 2011

Ultrasonic welding is widely used in bonding of the same kind or dissimilar materials. The important variable of ultrasonic bonding is the bonding pressure, bonding time and applied amplitude energy. These variables have to be optimized in order to obtain the optimum bonding results. In this research, the important factor to optimal bonding between metal and glass were experimentally investigated by applying design of experiment.