• Journal of Welding and Joining
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• v.18 no.4
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• pp.96-103
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• 2000

This study investigated the effects of bonding temperature and bonding atmosphere on high temperature mechanical properties of transient liquid phase(TLP) bonded joints of heat resistant alloy using MBF-50 insert metal. Specimens were bonded at 1,423~1,468K for 600s. Microconstituents of {TEX}$Cr_{7}(C,B)_{3}${/TEX}were formed in the bonded region when the bonding temperature was low. The amount of microcostituents in the bonded layer decreased with increasing the bonding temperature, and the microconstituents in the bonded layer disappeared at the bonding temperature above 1,468K. The tensile strength of the joints at elevated temperatures increased with the increase the bonding temperature and was the same level as one of the base metal in the bonding temperature over 1,453K. Microstructure and alloying element distributions of the bonded region bonded in Ar and $N_2$atmosphere were similar to those of the bonded in vacuum. The creep rupture strength and rupture lives of joints were almost identical to those of base metal.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.04a
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• pp.778-782
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• 1996

By the use of a similar numerical method as that in the previous paper, the forming limit strain of bonded sheet metals is investigated, in which the FEM is applied and J2G(J2-Gotoh's corner theory) is utilized as the plasticity constitutive equation. Bonded two-layer sheets and sheets bonded with dissimilar sheets on both surface planes are stretched in a plane-strain state, with various work-hardening exponent n-values and thicknesses of each layer. Processes of shear-band formation in such composite sheets are clearly illustrated. It is concluded that, in the bonded state, the higher limiting strain of one layer is reduced due to the lower limiting strain of the other layer and vice versa, and does not necessarily obey the rule of linear combination of the limiting strain of each layer weighted according thickness.

• Journal of Welding and Joining
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• v.32 no.4
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• pp.46-54
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• 2014

In this study, the effect of bonding temperature and bonding pressure on deformation and tensile properties of diffusion bonded joint of STS304 compact heat exchanger was investigated. The diffusion bonds were prepared at 700, 800 and $900^{\circ}C$ for 30, 60 and 90 min in pressure of 3, 5, and 7 MPa under high vacuum condition. The height deformation of joint decreased and the width deformation of joint increased with increasing bonding pressure at $900^{\circ}C$. The ratio of non-bonded layer and void observed in the joint decreased with increasing bonding temperature and bonding pressure. Three types of the fracture surface were observed after tensile test. The non-bonded layer was observed in diffusion bonded joint preformed at $700^{\circ}C$, the non-bonded layer and void were observed at $800^{\circ}C$. On the other hand, the ductile fracture occurred in diffusion bonded joint preformed at $900^{\circ}C$. Tensile load of joint bonded at $800^{\circ}C$ was proportional to length of bonded layer and tensile load of joint bonded at $900^{\circ}C$ was proportional to minimum width of pattern. The tensile strength of joint was same as base metal.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.10 no.1
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• pp.127-132
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• 2001

By the use of a similar numerical method as the forming limit strain by coating method of coated sheet metals is investigated, in which the FEM is applied and J2G(J2-Gotohs Corner Theory) is utilized as the plasticity constitutive equa-tion. Circular bonded sheet metals with dissimilar sheets on both surface planes are stretched in a plane -strain state, with various work-hardening exponent n-values and thicknesses of each layer. Processes of shear-band formation in such com-posite sheets are clearly illustrated. It is concluded that, it the bonded state, the higher limiting strain of one layer is reduced due to the lower limiting strain of the other layer and vice versa, and does not necessarily obey the rule of linear combination of the limiting strain of each layer weighed according thickness.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.04a
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• pp.921-926
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• 1997

SOI(Silicon On lnsulator) technology is many advantages in the gabrication of MOS(Metal-Oxide Semiconductor) and CMOS(Complementary MOS) structures. These include high speed, lower dynamic power consumption,greater packing density, increased radiation tolearence et al. In smiple form of bonded SOL wafer manufacturing, creation of a bonded SOI structure involves oxidizing at least one of the mirror polished silicon surfaces, cleaning the oxidized surface and the surface of the layer to which it will be bonded,bringing the two cleanded surfaces together in close physical proximity, allowing the subsequent room temperature bonding to proceed to completion, and than following this room temperature joining with some form of heat treatment step,and device wafer is thinned to the target thickness. This paper has been performed to investigate the possibility of the bonded SOI wafer manufacturing Especially, we focused on the bonding quality and thinning method. Finally,we achieved the bonded SOI wafer that Si layer thickness is below 3 .mu. m and average roughness is below 5.angs.

• Journal of the Korean Ceramic Society
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• v.46 no.5
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• pp.534-539
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• 2009

Reaction Bonded Silicon Carbide(RBSC) has been used for engineering ceramics due to low-temperature fabrication and near-net shape products with excellent structural properties such as thermal shock resistance, corrosion resistance and mechanical strength. Recently, attempts have been made to develop hot gas filter with gradient pore structure by RBSC to overcome weakness of commercial clay-bonded SiC filter such as low fracture toughness and low reliability. In this study a fabrication process of porous RBSC with multi-layer pore structure with gradient pore size was developed. The support layer of the RBSC with multi-layer pore structure was fabricated by conventional Si infiltration process. The intermediate and filter layers consisted of phenolic resin and fine SiC powder were prepared by dip-coating of the support RBSC in slurry of SiC and phenol resin. The temperature of $1550^{\circ}C$ to make Si left in RBSC support layer infiltrate into dip-coated layer to produce SiC by reacting with pyro-carbon from phenol resin.

• Journal of Welding and Joining
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• v.23 no.6
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• pp.67-71
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• 2005

This paper is concerned with a study on fracture strength of composites in an adhesive single lap joint. The tests were carried out on joint specimens made with hybrid stacked composites consisting of the polyester and bamboo natural fiber layer. The main objective of this work was to evaluate the fracture properties adjacent to adhesive bonded joint of natural fiber reinforced composite specimens. From the results, natural fiber reinforced composites have lower tensile strength than the original polyester. But tensile-shear strength of natural fiber reinforced composites with bamboo layer far from adhesive bond is as high as that of the original polyester adhesive bonded joints. Spew filet at the end of the overlap reduced the stress concentration at the bonded area. Spew fillet and position of bamboo natural fiber layer have a peat effect on the tensile-shear strength of natural fiber reinforced composites including adhesive bonded joints.

• Journal of Welding and Joining
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• v.24 no.5
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• pp.43-48
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• 2006

This paper is concerned with a fracture strength study of composite adhesive lap joints. The tests were carried out on specimen joints manufactured hybrid stacked composites such as the polyester and bamboo natural fiber layer. The main objective of the work was to test the fracture strength using hybrid stacked composites with a polyester and bamboo natural fiber layer. Tensile and peel strength of hybrid stacked composites are tested before appling adhesive bonding. From results, Natural fiber reinforced composites have lower tensile strength than the original polyester. and The load directional orientation and small amount and low thickness of bamboo natural fiber layer have a good effect on the tensile and peel strength of natural fiber reinforced composites. The failure strength of these materials applied adhesive bonding is also affected by fiber orientation and thickness of bamboo natural fiber layer. There for, Fiber orientation of bamboo natural fiber layer have a great effect on the tensile-shear strength of natural fiber reinforced composites including adhesive bonded joints.

• Journal of Powder Materials
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• v.4 no.3
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• pp.196-204
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• 1997

Joining of AIN ceramics to W and Cu by active-metal brazing method was tried with use of (Ag-Cu)-Ti alloy as insert-metal. Joints were produced under various conditions of temperature, holding time and Ti-content in (Ag-Cu) alloy Reaction and microstructural development in bonded interface were investigated through observation and analysis by SEM/EDS, EPMA and XRD. Joint strengths were measured by shear test. Bonded interface consists of two layers: an insert-metal layer of eutectic Ag- and Cu-rich phases and a reaction layer of TiN. Thickness of reaction layer increases with bonding temperature, holding time and Ti-content of insert-metal. It was confirmed that the growth of reaction layer is a diffusion-controlled process. Activation energy for this process was 260 KJ/mol which is lower than that for N diffusion in TiN. Maximum shear strength of 108 MPa and 72 MPa were obtained for AIN/W and AIN/Cu joints, respectively. Relationship between processing variables, joint strength and thickness of reaction layer was also explained.

• Structural Engineering and Mechanics
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• v.48 no.4
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• pp.479-500
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• 2013

This paper presents the experimental as well as analytical study conducted on layer-bonded scrap tire rubber pad (STRP) isolators to develop low-cost seismic isolators applicable to structures in developing countries. The STRP specimen samples were produced by stacking the STRP layers one on top of another with the application of adhesive. In unbonded application, the STRP bearings were placed between the substructure and superstructure without fastening between the contact surfaces which allows roll-off of the contact supports. The vertical compression and horizontal shear tests were conducted with varying axial loads. These results were used to compute the different mechanical properties of the STRP isolators including vertical stiffness, horizontal effective stiffness, average horizontal stiffness and effective damping ratios. The load-displacement relationships of STRP isolators obtained by experimental and finite element analysis results were found to be in close agreement. The tested STRP samples show energy dissipation capacity considerably greater than the natural rubber bearings. The layer-bonded STRP isolators serve positive incremental force resisting capacity up to the shear strain level of 150%.