Electrochemical Deposition and PVD Coatings as Alternatives to Chromium (VI)-Based Coatings: A Review

Chromium trioxide (hexavalent chromium) is listed as a substance of very high concern in Annex XIV of the REACH Regulation (EC) No 1907/2006. To manage risks and encourage replacement with safer alternatives, its use requires specific authorization. Due to their unique properties, acid baths with hexavalent chromium are widely used to create decorative and functional coatings, and replacing them with a single alternative is challenging. Chromium electroplating using solutions containing trivalent chromium is the most widely analyzed technology cited by applicants seeking authorization for its use as an alternative to chromium deposition from electrolytes containing hexavalent chromium. However, other technologies such as physical vapor deposition, nickel electro/electroless plating, and thermal spraying account for a considerable proportion of the analyzed technologies used to replace hexavalent-chromium-based solutions, as listed by the applicants for authorization. This work briefly reviews the research on the most promising alternatives to conventional chromium electroplating using hexavalent-chromium-containing baths and analyzes the industrial transition towards more sustainable alternatives.