• Composites Research
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• v.26 no.5
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• pp.295-302
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• 2013

In this study, Al5052/CFRP composites were fabricated for an automobile component by compression molding process inside a U-channel mold. Al5052 sheet were treated by sand blasting with two different particle sizes. Accordingly, surface roughness (Ra) values of $4.25{\mu}m$ and $1.85{\mu}m$ were obtained for the treated Al5052 sheets. The effect of surface roughness of Al5052 sheets on the adhesion and mechanical properties of Al5052/CFRP composites have been evaluated. Shear lap test and 3-point bending test were conducted. Results showed that the shear load for the composite fabricated by using the treated Al5052 sheets with Ra value of $1.85{\mu}m$ and $4.25{\mu}m$ were 3 and 5 times higher than Ra value of $0.73{\mu}m$ of the composite fabricated by using the untreated sheet. The bending stress of 200MPa was obtained for the composite fabricated with untreated Al5052 sheets. The bending stress increased to 400MPa when the composite fabricated from treated sheets. However, the bending stress was not influenced by treating condition through sand blasting.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2017.05a
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• pp.116.2-116.2
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• 2017

DLC (Diamond like carbon) 박막을 전극 재료로 활용하기 위해서는 높은 전기 저항과 금속성 기판에 대한 낮은 접착력을 극복해야 한다. 본 연구에서는 PECVD에 의해 합성 된 DLC/Ti 전극의 아크 중간층, 질소 도핑, 증착 및 열처리 온도가 접착 강도와 전기적 및 전기 화학적 특성에 주는 영향을 체계적으로 조사 하였다. 그 결과, arc ion plating (AIP) 법에 의해 증착 된 Ti/TiC 중간층의 도입은 스크래치 테스트와 전기화학적 싸이클 테스트에서 향상된 접착 강도 및 수명을 가져온다는 것을 확인 하였다. 그리고 arc 중간층에서의 arc droplet은 DLC 박막의 표면적을 넓혀 전기 화학적 활성도를 높이는 긍정적인 역할을 하였다. 소량의 질소 도핑은 DLC 막의 비저항을 크게 낮춰주었고, 전기화학적 활성도를 증가시켰다. 증착 온도가 높을수록 DLC 막의 sp2/sp3 비율이 증가하였고, 이에 따라 비저항은 감소하였으며 전기 화학적 활성도는 증가하였다. 반면, 가장 높은 전기화학적 전위창은 $300^{\circ}C$ 에서 얻어졌으며 더 높은 온도에서 감소하였다. 열처리 온도를 높일수록 비저항의 감소 및 전기 화학적 활성도가 증가한 반면, 전기화학적 전위창은 지속적으로 감소하였고, 높은 열처리 온도에서는 DLC 전극의 수명이 줄어드는 것을 확인 하였다.

• Journal of Adhesion and Interface
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• v.23 no.3
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• pp.87-93
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• 2022

To analyze the interfacial property between the fiber and the matrix, work of adhesion was used generally that was calculated by surface energies. In this paper, it was determined what types of contact angle measurement methods were more accurate between static and dynamic contact angle measurements. 4 types of glass fiber and epoxy resin were used each other to measure the contact angle. The contact angle was measured using two types, static and dynamic contact angle methods, and work of adhesion, W_a was calculated to compare interfacial properties. The interfacial property was evaluated using microdroplet pull-out test. Generally, the interfacial property was proportional to work of adhesion. In the case of static contact angle, however, work of adhesion was not consistent with interfacial property. It is because that dynamic contact angle measurement comparing to static contact angle could delete the error due to microdroplet size to minimize the surface area as well as the meniscus measuring error.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.6
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• pp.783-790
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• 2004

Adhesive-bonded joints are widely used in the industry. Recently, applications of adhesive bonding joints have been increased extensively in automobile and aircraft industry. The strength of adhesive joints is influenced by the surface roughness, adhesive shape, stress distribution, and etc. However, the magnitude of the influence has not yet been clarified because of the complexity of the phenomena. In this study, as the fundamental research of adhesive bonding joints, the effects of adhesive shape and loading speed on bonding strength properties and durability of aluminum to polycarbonate single-lap joints were studied. To evaluate the effect of adhesive shape, several modified shapes were used, and loading speeds were varied from 0.05 to 5 mm/min. As a result, the load-displacement distribution was shown a brittle fracture tendency. The trigonal edged single lap and bevelled lap joints showed the higher strength than the plain single lap, trigonal single lap, joggle lap and double lap joints in same adhesive area. The fractures of trigonal single lap and trigonal edged single lap joints that had the higher strength level were shown as the mixture type of the cohesive and interfacial-failure, mostly joggle lap joints that had the lower strength level were shown as the adhesive-failure.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.12
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• pp.143-148
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• 2007

Polyethylene is a typical hydrophobic material and it is difficult to bond the polyethylene material with metal material. Thus, it is important to modify the surface of polyethylene material to improve the bonding strength between the polyethylene and the metal materials. In this study, the surface modification of polyethylene material was investigated to improve the interfacial strength between the polyethylene and the steel materials. Polyethylene material was surface-modified in a plasma cleaner using an oxygen gas. Two cases of composites (surface-modified pelyethylene/steel composite and regular (as-received) pelyethylene/steel composite) were fabricated using a secondary bonding method. Shear and bending tests have been performed using the two cases of composites. The results showed that the contact angle did not change much as the modification time increased. However, the contact angle decreased from ${\sim}76^{\circ}\; to\;{\sim}41^{\circ}$ with the modification. The results also showed that the shear strength and the bending strength were improved about 3030 % and 7 %, respectively when the polyethylene was plasma-modified using an oxygen gas.

• Journal of Adhesion and Interface
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• v.6 no.2
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• pp.6-12
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• 2005

The plasma generally, ionized gas state, is the 4th material state composed the universe. Generating the plasma artificially has been studied by spending energy and it has a lot of applications in human's life. There are several merits to modify the surface of polymer using plasma. Above all, plasma maintains the property of polymer because of it changes the property of surface only. Also, it doesn't use a organic solvent and it is the environment friendship because of there are no waste under processing. Furthemore, in case of high-pressure plasma, it is possible that automated-processing continuously. In this study, we tried the reforming of surface to rise the adhesive strength between the material of polymer, experimented the rising of adhesive strength through a experiment of peel strength by virtue of processing time and using gas, confirmed the change of polymer's surface through measuring the surface contact angle analyzer and scanning electron microscopy (SEM).

• Transactions of the Korean Society of Mechanical Engineers A
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• v.32 no.4
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• pp.354-361
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• 2008

Cold rolled steel sheet for automotive was treated by Ar/$O_2$ atmospheric pressure plasma to improve the adhesive bonding strength. Through the contact angle test and calculation of surface free energy for cold rolled steel sheet, the changes of surface properties were investigated before and after plasma treatment. The contact angle was decreased and surface free energy was increased after plasma treatment. And the change of surface roughness and morphology were observed by AFM(Atomic Force Microscope). The surface roughness of steel sheet was slightly changed. Based on Taguchi method, single lap shear test was performed to investigate the effect of experimental parameter such as plasma power, treatment time and flow rate of $O_2$ gas. Results shows that the bonding strength of steel sheet treated in Ar/$O_2$ atmospheric pressure plasma was improved about 20% compared with untreated sheet.

• Composites Research
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• v.22 no.4
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• pp.13-19
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• 2009

Adhesive joints are widely used for structural joining applications in various fields and environmental conditions. Polyurethane adhesive is using for LNG carrier with cryogenic temperature condition. Even if similar polyurethane adhesive is used for different substrate, it shows different adhesion properties. Specially, variation of adhesion properties depending on the resin system or fiber is very important factor for selection of adhesive on industrial application. In present study, we got different peel strength according to the different test temperature when different polyurethane adhesive was used for same fiber reinforced composite. The main cause was investigated using by SEM and it was proven that the different adhesion property between glass fiber on composite surface and polyurethane adhesives at cryogenic temperature.

• Journal of Adhesion and Interface
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• v.9 no.2
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• pp.24-31
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• 2008

In this work, calcium hydroxide and magnesium carbonate as metal ionic crosslinking agents were used to introduce ionic crosslinking points to the ethylene vinylacetate (EVA) emulsions for the enhancement of water resistance and mechanical properties of emulsion films. The properties of EVA emulsion film were investigated in crosslinking density, thermal features, surface energy, and mechanical properties, such as tensile strength, elongation at break and tear strength. With the increasing content of metal ionic crosslinking agent, the crosslinking density of the EVA emulsion film increases, resulting into the improvement of water resistance. The surface energy and mechanical properties of the EVA emulsion film, however, showed somewhat different behaviors. The highest surface energy, tensile strength, and tear strength were observed when 0.4% for calcium hydroxide and 0.5% for magnesium carbonate was added respectively, because the EVA emulsion containing carboxylic acid forms strong carboxylate-metal bond of ionically-crosslinked system. Therefore, it can be concluded that metal ionic crosslinking agents, such as magnesium carbonate and calcium hydroxide are considered to improve water resistance and mechanical properties of the EVA emulsion.

• Journal of Adhesion and Interface
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• v.4 no.1
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• pp.18-27
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• 2003

Interfacial properties and microfailure degradation mechanisms of the oxygen-plasma treated biodegradable poly(p-dioxanone) (PPDO) fiber/poly(L-lactide) (PLLA)composites were investigated for the orthopedic applications as implant materials using micromechanical technique and surface wettability measurement. PPDO fiber reinforced PLLA composite can provide good mechanical performance for long hydrolysis time. The degree of degradation for PPDO fiber and PLLA matrix was measured by thermal analysis and optical observation. IFSS and work of adhesion, $W_a$ between PPDO fiber and PLLA matrix showed the maximum at the plasma treatment time, at 60 seconds. Work of adhesion was lineally proportional to the IFSS. PPDO fiber showed ductile microfailure modes at We initial state, whereas brittle microfailure modes appeared with elapsing hydrolysis time. Interfacial properties and microfailure degradation mechanisms can be important factors to control bioabsorbable composites performance because IFSS changes with hydrolytic degradation.