Properties of Cr–C–Al₂O₃ Deposits Prepared on a Cu Substrate Using Cr³⁺-Based Plating Baths

Cr–C–Al₂O₃ deposits with different Al₂O₃ concentrations were successfully prepared on a Cu substrate from Cr³⁺-based electroplating baths. The microstructures of the Cr–C–Al₂O₃ deposits were examined using optical, scanning, and transmission electron microscopes. The hardness values, the corrosion and wear resistance of the Cr–C and Cr–C–Al₂O₃ deposited specimens were evaluated. Based on the experimental results, Al₂O₃ nanoparticles were uniformly distributed within the Cr–C deposits after electroplating in a Cr³⁺-based plating bath. The hardness values of the Cr–C–Al₂O₃ deposits increased with the Al₂O₃ concentration in the electroplating bath. The corrosion resistance of the Cr–C-deposited specimens could be noticeably improved by adding Al₂O₃ nanoparticles to the deposit. This is attributed to decrease in the number of cracks in the Cr–C specimens codeposited with Al₂O₃ nanoparticles. According to the transmission electron microscopy study, the crack-reduction mechanism in the Cr–C–Al₂O₃ deposits was proposed. The Cr–C–Al₂O₃ deposited specimen, which was prepared in an electroplating bath with an Al₂O₃ concentration of 50 g/L, had a relatively high corrosion resistance compared to the other specimens.