• 한국분말재료학회지
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• 제13권1호
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• pp.62-67
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• 2006

Friction welding of $Al_2O_3$ particulate reinforced aluminum composites was performed and the following conclusions were drawn from the study of interfacial bonding characteristics and the relationship between experimental parameters of friction welding and interfacial bond strength. Highest bonded joint efficiency (HBJE) approaching $100\%$ was obtained from the post-brake timing, indicating that the bonding strength of the joint is close to that of the base material. For the pre-brake timing, HBJE was $65\%$. Most region of the bonded interface obtained from post-brake timing exhibited similar microstructure with the matrix or with very thin, fine-grained $Al_2O_3$ layer. This was attributed to the fact that the fine-grained $Al_2O_3$ layer forming at the bonding interface was drawn out circumferentially in this process. Joint efficiency of post-brake timing was always higher than that of pre-brake timing regardless of rotation speed employed. In order to guarantee the performance of friction welded joint similar to the efficiency of matrix, it is necessary to push out the fine-grained $Al_2O_3$ layer forming at the bonding interface circumferentially. As a result, microstructure of the bonded joint similar to that of the matrix with very thin, fine-grained $Al_2O_3$ layer can be obtained.

• Journal of Mechanical Science and Technology
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• 제15권10호
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• pp.1386-1397
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• 2001

In this paper, the plane elasticity equations are used to investigate the in-plane normal (mode I) and shear (mode II) behavior of a crack perpendicular to and terminating at the interface in bonded media with a graded interfacial zone. The interfacial Bone is treated as a nonhomogeneous interlayer with the continuously varying elastic modulus between the two dissimilar, homogeneous semi-infinite constituents. For each of the individual loading modes, based on the Fourier integral transform technique, a singular integral equation with a Cauchy kernel is derived in a separate but parallel manner. In the numerical results, the values of corresponding modes of stress intensity factors are illustrated for various combinations of material and geometric parameters of the bonded media in conjunction with the effect of the material nonhomogeneity within the graded interfacial zone.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집A
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• pp.286-291
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• 2001

Applications of bonded dissimilar materials such as IC package, ceramic/metal and resin/metal bonded joints, are very increasing in various industry fields. It is very important to analyze the thermal stress and stress singularity at interface edges in bonded joints of dissimilar materials. In orer to understand the package crack emanating from the edge of Die pad and Resin, fracture mechanics of bonded dissimilar materials and material properties are obtained. In this paper, the thermal stress and its singularity index for the IC package were analyzed using 2-dimensional elastic boundary element method. Crack propagation angle and path by thermal stress were numerically simulated with boundary element method.

• 한국자동차공학회논문집
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• 제16권3호
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• pp.15-22
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• 2008

Applications of bonded dissimilar materials such as integrated circuit(IC) packages, ceramics/metal and resin/metal bonded joints, are very increasing in various industry fields. It is very important to analyze the thermal stress and stress singularity at interface edge in bonded joints of dissimilar materials. In order to investigate the IC package crack propagating from the edge of die pad and resin, the fracture parameters of bonded dissimilar materials and material properties are obtained. In this paper, the thermal stress and its singularity index for the IC package were analyzed using 2-dimensional elastic boundary element method(BEM). From these results, crack propagation direction and path by thermal stress in the IC package were numerically simulated with boundary element method.

• Journal of Welding and Joining
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• 제19권1호
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• pp.82-87
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• 2001

The creep-rupture and low cycle fatigue properties of transient liquid phase bonded joints of Ni-base single crystal superalloy, CMSX-2 was investigated using MBF-80 insert metal. The (100) orientation of bonded specimen was aligned perpendicular to the joint interface. CMSX-2 was bonded at 1523K for 1.8ks in vacuum, optimum bonding condition. The creep rupture strength and rupture lives of the joints were the almost identical to ones of the base metal. SEM observation of the fracture surfaces of joints after creep rupture test revealed that the fracture surfaces classified three types of region, ductile fracture surface, cleavage fracture surface and interfacial fracture surface. The low cycle fatigue properties of the joints were also the same level as those of base metal. The elongation and reduction of area values of joints were comparable to those of base metal while fell down on creep rupture condition of high temperature.

• 대한치과교정학회지
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• 제22권2호
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• pp.289-296
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• 1992

The purpose of this study was to evaluate and compare the shear bond strengths and failure sites of metal brackets bonded with chemically cured adhesive and light-cured adhesive. 10 brackets were bonded on prepared enamel surfaces with $Transbond^{circledR}$ (Unitek/3M; U.S.A.) light-cured orthodontic adhesive and another 10 brackets were bonded with $Ortho-one^{\circledR}$ (Bisco:U.S.A.) chemically cured orthodontic adhesive. 24 hours after bonding, the Instron universal testing machine was used to measure the shear bond strengths. The failure sites were examined under streoscopic microscope. The results were as follows: 1 . The mean shear bond strength of metal brackets bonded with light-cured adhesive was lower than that of metal brackets bonded with chemically cured adhesive, but the difference was not statistically significant (p < 0.05). 2. Regardless of the type of adhesives, the brackets were failed primarily at the bracket base-adhesive interface. 3. Bonding of metal brackets with light-cured adhesive is considered to be clinically acceptable.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2002년도 Proceedings of the International Welding/Joining Conference-Korea
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• pp.798-802
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• 2002

Metallurgical studies on the bonded interlayer of directionally solidified Ni-base superalloy GTD111 joints were carried out during transient liquid phase bonding. The formation mechanism of solid during solidification process was also investigated. Microstructures at the bonded interlayer of joints were characterized with bonding temperature. In the bonding process held at 1403K, liquid insert metal was eliminated by well known mechanism of isothermal solidification process and formation of the solid from the liquid at the bonded interlayer were achieved by epitaxial growth. In addition, grain boundary formed at bonded interlayer is consistent with those of base metal. However, in the bonding process held at 1453K, extensive formation of the liquid phase was found to have taken place along dendrite boundaries and grain boundaries adjacent to bonded interlayer. Liquid phases were also observed at grain boundaries far from the bonding interface. This phenomenon results in liquation of grain boundaries. With prolonged holding, liquid phases decreased gradually and changed to isolated granules, but did not disappeared after holding for 7.2ks at 1473K. This isothermal solidification occurs by diffusion of Ti to be result in liquation. In addition, grain boundaries formed at bonded interlayer were corresponded with those of base metal. In the GTD-ll1 alloy, bonding mechanism differs with bonding temperature.

• 접착 및 계면
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• 제7권4호
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• pp.10-12
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• 2006

The successful use of adhesively bonded parts depends on the defect-free bond of the components. Therefore it is necessary to detect relevant faults and defects in an early state of the production. A 100% test should be pursued, but especially at complicated structures the detection of defects is not easy. Possible testing methods, which show a high potential for the NDT of adhesively bonded parts, are thermography based NDT methods. At present mainly two different procedures of active thermography are being used: Pulse and Lock-In Thermography. With pulse thermography the examined material is warmed up with a short energy pulse (light, eddy current or ultrasonic pulse) and the heat response is recorded after a certain time. The result is an infrared image which indicates material defects in different depths. This paper presents a variety of images showing the capability of Lock-In Thermography to image subsurface defects. Several examples of adhesives joints qualify the ultrasonic Lock-In-Thermography for the in-process quality control for adhesive bonded components.

• 접착 및 계면
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• 제21권1호
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• pp.20-26
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• 2020

Single lap-shear joints (SLJ) specimens with and without partial round fillets were fabricated to measure the average shear strength of adhesives. The effects of the length of the adherend on the SLJ specimens were also investigated. An epoxy adhesive was used to bond aluminum alloy. Tensile tests were performed on the adhesive bulk specimens to measure the mechanical properties. The finite element analysis (FEA) method was used to measure the adhesive stress distributions, i.e., the peel and shear stresses, on the bonded part. The experimental results revealed that the specimen consisting short length of adherend and without the partial round fillets exhibited the smallest average shear strength of adhesive among the investigated specimens. FEA revealed that the low average shear strength for the specimen with a short adherend length was caused by high stress concentrations on the adhesive at the edge of the bonded part.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 G
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• pp.3313-3315
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• 1999

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. A bond characteristic on the interface was analyzed by using IT- IR. Si-F bonds on Si surface after HF pre-treatment are replaced by Si-OH during a DI water rinse. Consequently, hydrophobic wafer was bonded by hydrogen bonding of Si $OH{\cdots}(HOH{\cdots}HOH{\cdots}HOH){\cdots}OH-Si$. The bond strength depends on the HF pre-treatment condition before pre- bonding (Min:$2.4kgf/crn^2{\sim}Max:14.9kgf/crn^2$)