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The microstructural features and mechanical properties of a B 4 C particle-reinforced Cu matrix composite prepared by friction stir welding (FSW) were investigated. For this purpose, the FSW process was carried out along a 0.6-mm-width gap, between two Cu plates, filled with boron carbide (B 4 C) particles. Microstructural observations taken in the stir zone (SZ) revealed that the presence of B 4 C particles led to the evolution of fine grains (∼2 μm). Based on the hardness measurements of the FSW-fabricated samples, the hardness values were significantly improved after the B 4 C particles were incorporated. [ABSTRACT FROM AUTHOR]

Carbon fiber reinforced plastic (CFRP) is increasingly considered for various industrial applications. CFRP has been applied to the automotive industry to increase fuel efficiency due to its excellent strength and lightweight. Therefore, the demand for dissimilar material joining techniques is gradually increasing. In this study, we investigated the intense pulsed light (IPL) as surface treatment for CFRP. The IPL surface treatment requires a very short processing time and can be easily automated compared with other processes such as chemical and mechanical treatments. The change in morphology and chemical composition of the CFRP-treated surfaces was analyzed using scanning electron microscopy, profiler, and X-ray photoelectron spectroscopy. The bonding strength due to varying IPL exposure time was evaluated by the lap shear test. The apparent shear strength increased by up to 159% in this study. The IPL treatment is very simple and requires short processing time to produce enhanced adhesive joints. [ABSTRACT FROM AUTHOR]

Abstract We investigated the effect of Ag-coated multi-walled carbon nanotubes (Ag-MWCNT) on the microstructures and electromigration behaviors of a Sn58%Bi solder and organic solderability preservative (OSP) surface finished on the FR-4 printed circuit board (PCB) joint under a current stress of 3000 A/cm2 at 100 °C. Electromigration of Ag-MWCNT Sn58%Bi composite solder was investigated by daisy-chain test-kit. Reaction layers formed at the anode side and cathode side of the Sn58%Bi solder joints consisted of three microstructures; Bi-rich layer, Sn-rich layer, and intermetallic compounds (IMCs, Cu 6 Sn 5 and Cu 3 Sn). The Bi-rich layer was mainly formed at the anode side in the couple of the Sn58%Bi solder joint with various times of applying current stress. The Bi-rich layer of the Ag-MWCNT Sn58%Bi composite solder joint was approximately 2 times thinner than that of the Sn58%Bi solder joint because the Ag-MWCNT acts as a diffusion barrier. Also, the Cu 6 Sn 5 and Cu 3 Sn IMCs that formed at the interface between the Ag-MWCNT Sn58%Bi composite solder joints were thinner than those of the Sn58%Bi solder joints. The time to failure (TTF) was longest at the 0.05% Ag-MWCNT Sn58%Bi composite solder joint. Therefore, Ag MWCNT is expected to improve the reliability of electromigration in the Sn58%Bi composite solder joint. Highlights • The electromigration of the Ag-MWCNT Sn58%Bi composite solders were investigated. • Ag-coated MWCNTs were widely distributed in the Sn58%Bi solder joint. • MWCNT suppressed growths of Cu-Sn IMCs and Bi-rich layer under current stress. • TTF value of the 0.05 wt% Ag-MWCNT Sn58%Bi composite solder joint was the longest. [ABSTRACT FROM AUTHOR]