Fabrication and performance of carbon-sol-reinforced Cu composite coatings

This study successfully developed a series of carbon-sol-reinforced copper (Cu-CS) composite coatings by electrodeposition employing a superiorly dispersed carbon sol (CS) to avoid nanoparticle aggregation. The CS, characterized using transmission electron microscopy and zeta potential analysis, consisted of carbon particles with an approximate diameter of 300 nm uniformly distributed in the electrolytes. The characteristics of the composite coating were examined via scanning electron microscopy to observe its microstructures, X-ray diffraction to detect its phase constituents, and durability testing to determine the wear and corrosion resistance. Results indicated a significant improvement in coating thickness, density, and uniformity achieved for the Cu-CS composite coating with the addition of 20 mL/L CS. Moreover, the Cu-CS composite coating exhibited a low wear volume (1.15 × 10⁻³ mm³), a high hardness (HV_0.5 137.1), and a low corrosion rate (0.191 mm/a). The significant contribution of carbon particles to the improvement of coating performance is mainly influenced by two factors, namely, the strengthening and lubricating effects resulting from the incorporated carbon particles. Nevertheless, overdosage of CS can compromise the microstructure of the Cu-CS composite coating, creating defects and undermining its functionality.