Thermal Cycling에 따른 자가중합 레진의 결합강도에 관한 연구

조혜원,하점임,Cho, Hye-Won,Ha, Jum-In 대한치과보철학회 1997 대한치과보철학회지 Vol.35 No.4

The purpose of this study was to evaluate the effects of two metal adhesive primers on the shear bond strengths of self-curing resin to Ni-Cr a]toy and the effects of 1000 thermal cycling on the durability of the bond. The two selected metal adhesive primers were Metal Primer II(G-C corp., Japan) and MR Bond(Tokuyama corp., Japan) and no treatment groups were used as control. All specimens were divided into two groups according to thermal cycling. In the group without thermal cycling, the specimens were stored in water for 24 hours. In the group with thermal cycling, the specimens were thermocycled 1000 times at temperature of $5^{\circ}C\;and\;55^{\circ}C$. Shear bond strengths were measured using the Universal testing machine(Zwick 145641, Germany) with a crosshead speed of 0.5 mm/min. The results were as follows: 1. MR Bond significantly improved the shear bond strength of resin to Ni-Cr alloy before and after thermal cycling. 2. There were no difference in the shear bond strength of resin to Ni-Cr alloy between Metal Primer II treated group and no treatment group. 3. Regardless of the type and the use of adhesive primers, there were tendency of decrease in shear bond strength with 1000 thermal cycling.

제동디스크의 코팅 두께에 따른 열응력 2D 해석 모델 연구

전지훈,이호용,김민수 한국산학기술학회 2022 한국산학기술학회논문지 Vol.23 No.12

A braking system is a structure in which a braking force is generated by friction between friction material and a braking disc. Wear occurs due to braking action, which causes the occurrence of fine dust, which has recently become an issue. Eco-friendly research is being actively conducted domestically and abroad to reduce fine dust. In order to reduce fine dust, a coating layer should be formed on the surface of the braking disc in various ways to reduce wear and maintain braking performance. However, high heat is generated due to friction, and as a result, heat is accumulated on the surface of the braking disc, thereby generating high thermal stress. Research is needed to minimize thermal stress because the difference in the thermal expansion rate between the coated layer, the base material part, and the bond layer that bonds the two layers generates higher thermal stress, which greatly affects the braking disc. Therefore, in this study, the thermal stress according to the thickness of the coating layer and bond layer was derived from the coating surface of a braking disc through thermal-structure linkage analysis. The correlation between the coating thickness and thermal stress was analyzed. A micro-structured 2D analysis model is proposed to correlate the coating layer, bonding layer, base material parts, and materials with various thicknesses and to save analysis time. The thermal stress of each layer was derived based on braking test data. Using the analysis of the results, a model for optimization was obtained. 일반적으로 제동시스템의 특징은 마찰재와 제동디스크 사이의 마찰 작용에 의해 제동력이 발생되는 구조이다. 이때 제동작용으로 인해 마모가 발생하고 이는 최근에 이슈가 되고 있는 미세먼지의 발생 원인이 된다. 이때 발생하는 미세먼지 저감을 위한 국내외에서는 친환경적인 연구가 활발하게 진행되고 있다. 미세먼지를 저감하기 위해서는 제동디스크의 표면에 다양한 방법으로 코팅층을 형성하여 마모량을 줄이고 제동 성능을 유지할 수 있도록 설계해야 한다. 하지만, 마찰로 인해 높은 열이 발생되고 이로 인해 제동디스크 표면에 열이 축적되어 높은 열응력을 생성한다. 또한 코팅층과 모재부 그리고 두층을 접합시켜주는 본드층의 열팽창률 차이로 인해 더 높은 열응력이 발생되고, 열응력은 제동디스크 균열에 큰 영향을 미치기 때문에 열응력을 최소화하는 연구가 필요하다. 따라서 본 연구에서는 열-구조 연계해석을 통해 제동디스크의 코팅표면에서 코팅층 및 본드층의 두께에 따른 열응력 해석결과를 도출하고 코팅 두께와 열응력과의 상관관계를 분석하였다. 다양한 두께를 갖는 코팅층, 본드층 및 모재부와 각층을 구성하는 재료들의 상관관계를 분석하고, 정밀한 모델링과 유사하면서 해석시간을 절약할 수 있는 미세구조의 2D 해석 모델을 제안하였으며, 제동시험 데이터를 기준으로 온도 조건을 부여하여 각 층의 열응력을 도출하였다. 또한 결과 분석을 통해 코팅층 및 본드층 각각의 두께가 증가함에 따라 열응력이 변화하는 상관관계를 해석하고 최적화를 위한 모델을 제시하고자 하였다.

열초음파 접합 공정과 접합부의 신뢰성 평가에 관한 연구

신영의,박진석,손선익,Shin, Young-Eui,Pak, Jin-Suk,Son, Sun-Eik 한국전기전자재료학회 2009 전기전자재료학회논문지 Vol.22 No.8

In this thesis, lateral thermosonic bonding with ACFs was investigated as a process to make high reliability joints for FPD fabrication. Conditions for thermosonic and thermocompression bonding with ACFs were determined and used to make specimens in a driving test jig for testing of bond reliability by thermal shock. The results showed that thermosonic bonding temperature of $199\;^{\circ}C$ and bonding time of 1s produced bonds with good reliability. Additionally, thermosonic bonding temperature and time were reduced and thermal shock test results compared to this proposed curing condition. It is concluded that theromosonic bonding with ACFs can be effectively applied to reduce bonding temperature and time compared with that of thermocompression bonding.

고강력 직물의 열융착 라미네이팅을 통한 충격 완화용 에어쿠션 소재로의 적용 가능성 검토 연구

김지연,김훈민,민문홍 한국염색가공학회 2020 韓國染色加工學會誌 Vol.32 No.3

In order to study wearable air cushion materials capable of responding to massive impact in high-altitude fall situation, high tenacity woven fabrics were bonded by heat only depending on various type of thermoplastic films and then mechanical properties were measured. Tensile strength, elongation, and 100% modulus measurement results for 4 types of films show that TPU-2 has higher impact resistance and easier expansion than PET-1. After thermal bonding, the combination with the highest tensile strength was a material with a TPU-2 film for nylon and a PET-2 film for PET, so there was a difference by type of fabric. The tear strength of the bonded materials were increased compared to the fabric alone, which shows that durability against damage such as tearing can be obtained through film adhesion. All of the peel strengths exceeded the values r e quired by automobile airbags by about 5 times, and the TPU-2 bonded fabric showed the highest value. The air permeability was 0 L/dm2/min. For both the film and the bonded material, which means tightness between the fabric and the film through thermal bonding. It is expected to be applied as a wearable air cushion material by achieving a level of mechanical properties similar to or superior to that of automobile airbags through the method of bonding film and fabric by thermal bonding.

A Study on Diffusion Bonding Performance of Inconel 617 Heat Exchanger

송찬호,Il Hwan Cho,최준석 한국정밀공학회 2015 International Journal of Precision Engineering and Vol. No.

This paper proposes diffusion bonding characteristics of a heat exchanger whose material is Inconel. In order to respond to high temperature and pressure operating conditions, the diffusion bonding technology and Inconel 617 material were applied to the heat exchanger. However, it is difficult to estimate how well the diffusion-bonded Inconel heat exchanger is made. In this paper, the bonding performance for the diffusion-bonded heat exchanger was examined and analyzed. The analysis with measuring thermal and mechanical properties such as thermal diffusivity and tensile strength were conducted and parametric studies about bonding temperature and pressing force were carried out. The bonding condition of 1200oC, 50 ton was found to be suitable for this heat exchanger. Through thermal resistance model, impurity management with 10 μm level would be expected to be necessary. Besides pressure-resistant test, the deformation in the stacking direction of the plates was found to be important observation element. The heat exchanger was tested for evaluating its capability where the performance showed 10 kW for capacity and 0.7 for effectiveness at 1.5 kg/min. From the results, we were able to establish the base technology for the manufacture of Inconel 617 heat exchanger through the application of the diffusion bonding.

IPA 저온 접합법을 이용한 PMMA Micro CE Chip의 제작

차남구,박창화,임현우,조민수,박진구,Cha, Nam-Goo,Park, Chang-Hwa,Lim, Hyun-Woo,Cho, Min-Soo,Park, Jin-Goo 한국재료학회 2006 한국재료학회지 Vol.16 No.2

This paper reports an improved bonding method using the IPA (isopropyl alcohol) assisted low-temperature bonding process for the PMMA (polymethylmethacrylate) micro CE (capillary electrophoresis) chip. There is a problem about channel deformations during the conventional processes such as thermal bonding and solvent bonding methods. The bonding test using an IPA showed good results without channel deformations over 4 inch PMMA wafer at $60^{\circ}C$ and 1.3 bar for 10 minutes. The mechanism of IPA bonding was attributed to the formation of a small amount of vaporized acetone made from the oxidized IPA which allows to solvent bonding. To verify the usefulness of the IPA assisted low-temperature bonding process, the PMMA micro CE chip which had a $45{\mu}m$ channel height was fabricated by hot embossing process. A functional test of the fabricated CE chip was demonstrated by the separation of fluorescein and dichlorofluorescein. Any leakage of liquids was not observed during the test and the electropherogram result was successfully achieved. An IPA assisted low-temperature bonding process could be an easy and effective way to fabricate the PMMA micro CE chip and would help to increase the yield.

A review on the failure behavior and countermeasures of thermal barrier coatings

Jiahang Liu,Zhe Lu,Yanwen Zhou,Jing Zhang,Guanlin Lyu 한양대학교 청정에너지연구소 2023 Journal of Ceramic Processing Research Vol.24 No.2

Thermal barrier coatings are widely used in high-temperature components in aircraft thrusters, power generation, and marineengines, enabling gas turbines to operate at elevated temperatures for extended periods by reducing the superalloys' surfacetemperature. During service, high-temperature oxidation, hot corrosion, and sintering occur inside the thermal barriercoatings, resulting in changes in the macro and microstructure of the coatings, and thermal-mechanical propertiesdegradation, eventually leading to coating failure. The main factors that lead to the failure of thermal barrier coatings andaffect the life of thermal barrier coatings are reviewed, including the formation of thermally grown oxides on the surface ofthe bond coat, the corrosion caused by the deposits on the surface of the coating and the sintering of the high-temperatureceramic layer, and the failure mechanism of the coating is analyzed. The countermeasures to prolong the service life of coatingsare reviewed from thermal barrier coating materials, coating structure, coating preparation methods, and post-treatment.

인코넬 617을 이용한 고온고압용 미세채널 열교환기의 확산접합 공정에 관한 연구

송찬호(Chan Ho Song),윤석호(Seok Ho Yoon),최준석(Joon Seok Choi) 대한설비공학회 2015 설비공학 논문집 Vol.27 No.2

Recently, the heat exchangers are requiring higher performance and reliability since they are being used under the operating condition of high temperature and pressure. To satisfy these requirements, we need special materials and bonding technology. This study presents a manufacturing technology for high temperature and high pressure micro channel heat exchanger using Inconel 617. The bonding performance for diffusion bonded heat exchanger was examined and analyzed. The analysis were conducted by measuring thermal and mechanical properties such as thermal diffusivity and tensile strength, and parametric studies about bonding temperature and pressing force were also carried out. The results provided insight for bonding evaluation and the bonding condition of 1200℃, and 50 tons was found to be suitable for this heat exchanger. From the results, we were able to establish the base technology for the manufacturing of Inconel 617 heat exchanger through the application of the diffusion bonding.

Thermal-pressure loading effect on containment structure

Kwak, Hyo-Gyoung,Kwon, Yangsu Techno-Press 2014 Structural Engineering and Mechanics, An Int'l Jou Vol.50 No.5

Because the elevated temperature degrades the mechanical properties of materials used in containments, the global behavior of containments subjected to the internal pressure under high temperature is remarkably different from that subjected to the internal pressure only. This paper concentrates on the nonlinear finite element analyses of the nuclear power plant containment structures, and the importance for the consideration of the elevated temperature effect has been emphasized because severe accident usually accompanies internal high pressure together with a high temperature increase. In addition to the consideration of nonlinear effects in the containment structure such as the tension stiffening and bond-slip effects, the change in material properties under elevated temperature is also taken into account. This paper, accordingly, focuses on the three-dimensional nonlinear analyses with thermal effects. Upon the comparison of experiment data with numerical results for the SNL 1/4 PCCV tested by internal pressure only, three-dimensional analyses for the same structure have been performed by considering internal pressure and temperature loadings designed for two kinds of severe accidents of Saturated Station Condition (SSC) and Station Black-out Scenario (SBO). Through the difference in the structural behavior of containment structures according to the addition of temperature loading, the importance of elevated temperature effect on the ultimate resisting capacity of PCCV has been emphasized.

Thermal-pressure loading effect on containment structure

곽효경,권양수 국제구조공학회 2014 Structural Engineering and Mechanics, An Int'l Jou Vol.50 No.5

Because the elevated temperature degrades the mechanical properties of materials used in containments, the global behavior of containments subjected to the internal pressure under high temperature is remarkably different from that subjected to the internal pressure only. This paper concentrates on the nonlinear finite element analyses of the nuclear power plant containment structures, and the importance for the consideration of the elevated temperature effect has been emphasized because severe accident usually accompanies internal high pressure together with a high temperature increase. In addition to the consideration of nonlinear effects in the containment structure such as the tension stiffening and bond-slip effects, the change in material properties under elevated temperature is also taken into account. This paper, accordingly, focuses on the three-dimensional nonlinear analyses with thermal effects. Upon the comparison of experiment data with numerical results for the SNL 1/4 PCCV tested by internal pressure only, threedimensional analyses for the same structure have been performed by considering internal pressure and temperature loadings designed for two kinds of severe accidents of Saturated Station Condition (SSC) and Station Black-out Scenario (SBO). Through the difference in the structural behavior of containment structures according to the addition of temperature loading, the importance of elevated temperature effect onthe ultimate resisting capacity of PCCV has been emphasized.