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Vol.51, No.9, 655 ~ 665, 2013
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| Title |
| Effect of Surface Roughness on the Bonding Interface Properties of Hot-Pressed Cu/Al Clad Material |
| 이상목 Sang Mok Lee , 이종섭 Jong Sup Lee , 김용배 Yong Bae Kim , 이근안 Geun An Lee , 이상필 Sang Pill Lee , 손인수 In Soo Son , 이진경 Jin Kyung Lee , 배동수 Dong Su Bae |
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| Abstract |
| This study investigates the effect of surface roughness on bonding interface properties, such as micro hardness, diffusion layer thickness, intermediate phases, bonding strength, etc., in hot pressed Cu/Al clad material for electric conductors. Different surface roughnesses at the bonding surfaces of oxygen free copper (OFC) and Al 1050 matrix materials were obtained by emery paper grinding and buff polishing. The Cu/Al clad materials were prepared by hot-pressing under 200 MPa at 450 ℃ for 15 min. Microstructures of the Cu/Al interfaces were observed using an optical micrograph (OM), a Field Emission Gun-Scanning Electron Microscope (FEG-SEM) and an Energy Dispersed X-ray Analyser (EDX) in order to investigate the effects of surface roughness on the bond properties of the Cu/Al clad materials. A shear fracture test was performed to evaluate the bonding strengths of the Cu/Al clad materials. A Micro Knoop hardness test was used to measure the micro hardness in the diffusion layer at the Cu/Al interface. The 3-layer diffusion layer was observed at the Cu/Al interfaces. The thickness of the diffusion layer decreased and an additional intermediate phase ξ2 was formed with the increase of surface roughness. The Micro Knoop hardness increased rapidly mainly due to the formation of η2 and ξ2 phases and then decreased gradually with the increase of surface roughness. The bonding strength of the Cu/Al interface increased rapidly in the initial stage and increased slowly up to the peak value and then decreased slightly with the increase of surface roughness. The shear fracture surfaces of the Cu/Al bonding interface were flat and had an even shape in the sample with a low surface roughness, but had a rough and uneven shape in high surface roughness conditions. |
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| Key Words |
| composites, surface roughness, joining, interfaces intermetallics, scanning electron microscopy |
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