Microstructure and mechanical properties of copper surface composite layers reinforced by nano and microscale SiC particles via friction stir processing

Abstract

Although the high thermal and electrical conductivity properties of copper (Cu) have resulted in its widespread industrial applications, its weak surface properties usually caused some limitations. In this study, the effect of graphite (Gr) and silicon carbide nanoparticles (SiCNPs) on the surface properties of copper metal-matrix composites (CMMCs) was investigated. Friction stir processing (FSP) was applied to the preparation of the Cu/SiCNPs, Cu/Gr and Cu/SiCNPs+Gr CMMCs. Then the microstructures, hardness and wear properties of the prepared surface composites were investigated and compared with samples in the absence of reinforcement particles. Evaluation of the microstructure of composites showed an extensive reduction in grain size compared to FSPed metal (e.g., 70 µm in FSPed copper to an average of 300 nm in the Cu/SiCNPs). The results also showed that the hardness of Cu/SiCNPs composites is 100 HV, which is much higher than that of FSPed copper (with the hardness of about 60 HV). The wear test results showed that the presence of SiCNPs alone and with SiCNPs+Gr particles increase the coefficient of friction, relative to FSPed copper, while the presence of Gr particles alone results in a significant reduction of this parameter.

Keywords:

• copper metal matrix composites
• friction stir processing
• nano-sized silicon carbide
• graphite
• wear
• microhardness

Disclosure statement

No potential conflict of interest was reported by the authors.