Development and optimization of trivalent chromium electrodeposit on 304L stainless steel to improve corrosion resistance in chloride-containing environment

In this study, we developed and optimized a trivalent chromium coating electrodeposited on 304L stainless steel (SS) from a Cr-trivalent bath. The results reveal that the Cr coatings at all bath temperatures except for 80 °C showed clusters of polyhedral grains, however, the grain sizes decreased with an increase in bath temperature. Also, the coatings deposited at bath temperatures of 30, 50, and 60 °C experienced networks of cracks, which decreased in population density as temperature increased. However, the coatings deposited at bath temperatures of 70 and 80 °C were crack-free due to surface modification, confirmed by 3D profile results with an advanced power spectral density and a multi-Gaussian histogram analysis. The mechanical test results demonstrate that the adhesion and wear resistance of the Cr-coatings formed on the SS substrate significantly improved, with the optimal coefficient of friction of 0.18. Likewise, electrochemical behavior observations of the Cr coatings show that pitting resistance improved with the increase in bath temperature conditions, as shown in the pitting potential values which increased from 272.6 mV to 436.2 mV as bath temperature increases from 30 °C to 80 °C. From this study, it is proposed that the Cr-coatings deposited at a bath temperature of 80 °C presents the optimal coating performance concerning a combination of all the target qualities aimed, such as better tribological behavior and improved pitting resistance. Thus, enabling the establishment of an innovative method to overcome the conventional issues encountered in Cr electrodeposition of SSs.