High-speed electrodeposition of bright Cu with excellent mechanical properties utilizing friction of hard particles.

The electrodeposition rate is important for improving the application prospects and fabrication efficiency of Cu electrodeposition. However, high electrodeposition rates may result in reduced mechanical properties and surface quality of the deposited layer. In this article, high-speed electrodeposition of bright Cu with low surface roughness and excellent mechanical properties was achieved using friction-assisted electrodeposition (FAED). The mechanisms of the high luminance and low roughness on the deposited surface after FAED were analyzed from the perspective of geometrical optics. The results showed that mirror luminance with a low roughness of R_a 0.613 μm was obtained with hard particles by reducing the diffuse reflection and bulges on the deposited surface. The electrochemical behaviors of FAED and traditional electrodeposition were compared using electrochemical tests. The results indicated that hard particles increased the limiting current density by thinning the diffusion layer; thus, a high electrodeposition rate of 7.1 μm min⁻¹ was realized in FAED because it could proceed at higher current densities. Moreover, FAED achieved grain refinement and heterostructures because hard particles allowed periodic overpotential by disturbing the electroreduction process. The heterostructure provided an unusual synergy between high strength (486 MPa) and superior ductility (20.1%) by back-stress strengthening and hardening. The results not only broaden new understanding in the mechanism of FAED, but also lay the foundation for extending the applications of Cu electrodeposition. [ABSTRACT FROM AUTHOR]