• Journal of Welding and Joining
• /
• v.34 no.6
• /
• pp.28-34
• /
• 2016

Galvannealed(GA) steels are now generally used in car body manufacturing for corrosion resistance. In this study, the weldability and joint mechanical behavior of a newly developed 1.2GPa grade GA ultra high strength TRIP(transformation induced plasticity) steel was investigated for three joining processes, such as adhesive bonding, resistance spot welding and weldbonding. Under both shear and peel stress conditions, the failure mode of the adhesive joints were the mixture of the adhesive cohesive failure, adhesive interface failure and coating layer failure. It means that the adhesion strength of GA coating onto the base metal was similar to that of adhesive bonding onto the GA coating. Under the shear stress condition, the weldbonding exerted to expand the optimal spot welding condition of 1.2GPa GA TRIP steel because the strength of adhesive bond overwhelmed that of the resistance spot weld. Under the peel stress condition, the weldbonding also exerted to expand the optimal spot welding condition of 1.2GPa GA TRIP steel by inducing the tear fracture mode rather than the partial plug fracture mode.

• Structural Engineering and Mechanics
• /
• v.83 no.5
• /
• pp.693-707
• /
• 2022

Bonded joints have proven their performance against conventional joining processes such as welding, riveting and bolting. The single-lap joint is the most widely used to characterize adhesive joints in tensile-shear loadings. However, the high stress concentrations in the adhesive joint due to the non-linearity of the applied loads generate a bending moment in the joint, resulting in high stresses at the adhesive edges. Geometric optimization of the bonded joint to reduce this high stress concentration prompted various researchers to perform geometric modifications of the adhesive and adherends at their free edges. Modifying both edges of the adhesive (spew) and the adherends (bevel) has proven to be an effective solution to reduce stresses at both edges and improve stress transfer at the inner part of the adhesive layer. The majority of research aimed at improving the geometry of the plate and adhesive edges has not considered the effect of temperature and water absorption in evaluating the strength of the joint. The objective of this work is to analyze, by the finite element method, the stress distribution in an adhesive joint between two 2024-T3 aluminum plates. The effects of the adhesive fillet and adherend bevel on the bonded joint stresses were taken into account. On the other hand, degradation of the mechanical properties of the adhesive following its exposure to moisture and temperature was found. The results clearly showed that the modification of the edges of the adhesive and of the bonding agent have an important role in the durability of the bond. Although the modification of the adhesive and bonding edges significantly improves the joint strength, the simultaneous exposure of the joint to temperature and moisture generates high stress concentrations in the adhesive joint that, in most cases, can easily reach the failure point of the material even at low applied stresses.

• Proceedings of the KACD Conference
• /
• 2001.11a
• /
• pp.560.1-560
• /
• 2001

To evaluate the micro-shear bond strength of current adhesive systems to cervical and mid-coronal enamel. Materials and Two commercially available resin adhesives were investigated; a self-etching primer system(Clearfil SE Bond, Kyraray) and a one-bottle adhesive system(Single Bond, 3M) intended for use with the total-etch wet-bonding technique were employed. Two regions of enamel, cervical and mid-coronal regions, were chosen from the buccal surface of extracted molars and were then bonded with each adhesive system and submitted to the micro-shear bond test.(중략)

• Elastomers and Composites
• /
• v.52 no.4
• /
• pp.295-302
• /
• 2017

Polyurethane dispersion (PUD) polymers were synthesized by using polyether and polyester polyol. The effect of ionomeric centers, r(NCO / OH) values, chain extender process, and chain extender types on the adhesion properties was investigated. In the case of polyether-based PUD, the ionic center, r value, chain extension process and chain extender types were not adjusted even after adjustment. In the case of polyester-based PUD, when the ionic center content was more than 2.5%, the state of adhesive strength was $2.0kgf/cm^2$ or more. On the other hand, the initial adhesive strength was excellent at about $1kgf/cm^2$ when the ionic center content was over 3.5%. When the r value was 1.3 or more, it was found that the initial bonding strength and the state of bonding strength were excellent at about $1kgf/cm^2$ and $2.1kgf/cm^2$ or higher, respectively. An IR spectrum analysis of the synthesized PUD confirmed that PUD was composed of urethane based on the N-H characteristic peak at $3340cm^{-1}$ and the urethane characteristic peak at $1730cm^{-1}$. Moreover, the characteristic peaks of the isocyanate ($2260cm^{-1}$) used in the preparation of the prepolymer were not observed. As a result, the residual -NCO was not observed, and urethane was completely synthesized.

• Journal of Korea Technical Association of The Pulp and Paper Industry
• /
• v.46 no.4
• /
• pp.44-53
• /
• 2014

This research were aimed at developing starches which have high preservability and high bonding strength from corn starch, modified cationic and oxidized corn starches, as compared to the fermented wheat starch. On the lining that attaching the base paper on the back of the work with paste, the coating weight was determined by the solid contents of the paste rather than the viscosity of paste. Adhesive strength and stiffness were also determined by the solid contents of the paste. Corn starch had lower solid contents, higher viscosity, and higher adhesive strength than other starches. In the iodine stain to the surface of peeled base paper off, paste deeply penetrated into the traditional Hanji than modern Hanji. And oxidized starch paste deeply penetrated into the paper layer than the cationic starch.

• Composites Research
• /
• v.23 no.6
• /
• pp.32-38
• /
• 2010

The effect of the atmospheric pressure plasma(APP) treatments is experimentally investigated to ascertain the optimum condition to yield the best adhesive properties between a polyamide woven fabric and acrylonitrile butadiene rubber(NBR). For the atmospheric pressure flame plasma(APFP) treatment, the optimum number of treatment at given conditions is 2 times. The thermal deformation of the fabric is more serious with increasing the number of APFP treatment. The adhesive strength of the case with APFP treated fabric is increased about 35% when compare to the case with non-APFP treated one for the interface(bonding agent one or two coatings). When the surface is coated twice with the bonding agent, the adhesive energy with APFP treated fabric is increased about 4 times. It was found that the surface modification of polyamide woven fabric by APFP treatment is a fast, economic and applicable method to improve the adhesive properties between woven fabric and rubber when compared to other APP treatments.

• The Journal of Advanced Prosthodontics
• /
• v.1 no.1
• /
• pp.41-46
• /
• 2009

STATEMENT OF PROBLEM. The poor chemical bonding of a denture base resin to cast titanium framework often introduces adhesive failure and increases microleakage. PURPOSE. This study evaluated the shear bond strengths of a heat cure denture base resin to commercially pure titanium, Ti-6Al-4V alloy and a cobalt-chromium alloy using two adhesive primers. MATERIAL AND MATHODS. Disks of commercially pure titanium, Ti-6Al-4V alloy and a cobalt-chromium alloy were cast. Specimens without the primer were also prepared and used as the controls. The shear bond strengths were measured on a screw-driven universal testing machine. RESULTS. The primers significantly(P < .05) improved the shear bond strengths of the heat cure resin to all metals. However, the specimens primed with the Alloy $primer^{(R)}$(MDP monomer) showed higher bond strength than those primed with the MR $bond^{(R)}$(MAC-10 monomer) on titanium. Only adhesive failure was observed at the metal-resin interface in the non-primed specimens, while the primed specimens showed mixed failure of adhesive and cohesive failure. CONCLUSIONS. The use of appropriate adhesive metal primers makes it possible not only to eliminate the need for surface preparation of the metal framework before applying the heat cure resins, but also reduce the need for retentive devices on the metal substructure. In particular, the Alloy $primer^{(R)}$, which contains the phosphoric acid monomer, MDP, might be clinically more acceptable for bonding a heat cure resin to titanium than a MR $bond^{(R)}$, which contains the carboxylic acid monomer, MAC-10.

• The korean journal of orthodontics
• /
• v.42 no.1
• /
• pp.32-38
• /
• 2012

Objective: The aim of this study was to compare the effects of different enamel conditioning techniques for bracket bonding. Methods: Ninety-one human premolars were randomly divided in six groups of 15 specimens each. The enamel surfaces of the teeth were etched with 35% orthophosphoric acid in Group 1, with a self-etching primer in Group 2, sandblasted in Group 3, sandblasted and etched with 35% orthophosphoric acid in Group 4, conditioned by Er:YAG laser in Group 5 and conditioned by Er:YAG laser and etched with 35% phosphoric acid gel respectively in Group 6. After enamel conditioning procedures, brackets were bonded and shear bonding test was performed. After debonding, adhesive remnant index scores were calculated for all groups. One tooth from each group were inspected by scanning electron microscope for evaluating the enamel surface characteristics. Results: The laser and acid etched group showed the highest mean shear bond strength (SBS) value ($13.61{\pm}1.14$ MPa) while sandblasted group yielded the lowest value ($3.12{\pm}0.61$ MPa). Conclusions: Although the SBS values were higher, the teeth in laser conditioned groups were highly damaged. Therefore, acid etching and self-etching techniques were found to be safer for orthodontic bracket bonding. Sandblasting method was found to generate inadequate bonding strength.

• Journal of the Korean Wood Science and Technology
• /
• v.39 no.4
• /
• pp.344-350
• /
• 2011

In this study, LVLs of radiata pine were fabricated with non-preservative treated veneers, CuAz treated veneers, and ACQ treated veneers, using aqueous vinyl urethane adhesive and phenol modified resorcinol resin adhesive. Then density gradient, bonding strength, bending properties and decay resistance of LVLs were evaluated. As results, the cone-shaped and higher density gradient pattern was found in layer close to glueline. After cyclic water boiled test, the LVL bonded with aqueous vinyl urethane resin adhesive was delaminated in all layers or partly delaminated including check, chasm in glueline layer. In the case of LVL bonded with phenol modified resorcinol resin adhesive, despite slight cupping due to great glueline stress and vertical check between glueline layers, it was observed that the bonding strength to delamination was higher, owing to most absence of delamination through overall glueline. On the other hand, in the decay test, mass loss by brown rot fungi was greater than white rot fungi in LVL bonded with aqueous vinyl urethane resin adhesive. However, in LVL bonded with phenol modified resorcinol resin adhesive, the mass loss by brown rot fungi was slight and non-preservative treated LVL was low. The mass loss of preservative-treated LVL was 0 (zero), showing the high decay resistance effect.

• Steel and Composite Structures
• /
• v.20 no.3
• /
• pp.671-692
• /
• 2016

FRP stay-in-place (SIP) formworks are designed as a support for casting concrete and as a tension reinforcement when concrete is cured. Bond development between SIP formwork and concrete is critical for FRP tension element to be effective. This paper reports the bond strength between FRP formwork and concrete for different interfacial treatments. A novel experimental setup is prepared for observing the bond behaviour. Three different adhesives with varying workability have been investigated. Along with the load-deformation characteristics, bond slip and strains in the formwork have been measured. A finite element numerical simulation was conducted for the experiments to understand the underlying mechanism. The results show that the adhesive bonding has the best bond strength.