Nanocrystalline hard chromium electrodeposition from trivalent chromium bath containing carbamide and formic acid: Structure, composition, electrochemical corrosion behavior, hardness and wear characteristics of deposits

• Published in: Applied surface science 2011-07, Vol.257 (18), p.8048-8053
• Main Authors: Danilov, F.I., Protsenko, V.S., Gordiienko, V.O., Kwon, S.C., Lee, J.Y., Kim, M.
• Format: Article
• Language: English
• Subjects: Atomic structure; Carbamides; Chromium; Coatings; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Deposition; Electrodeposition, electroplating; Exact sciences and technology; Formic acid; Hard chromium electrodeposition; Hardness; Materials science; Mechanical and acoustical properties; Methods of deposition of films and coatings; film growth and epitaxy; Nanocrystalline coatings; Nanocrystals; Physical properties of thin films, nonelectronic; Physics; Structure and morphology; thickness; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Thin film structure and morphology; Trivalent chromium; Trivalent chromium bath; Wear; Wear characteristics
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2011.04.095

► The Cr–C electrodeposits have a nanocrystalline type of structure. ► Carbon is present as chromium carbide. ► The deposits exhibit an absence of the active dissolution range in acid solution. ► The hardness and wear characteristics were investigated. The paper is devoted to the structure, composition and properties investigations of coatings obtained from a sulfate trivalent chromium bath containing formic acid and carbamide as the complexing agents. The results indicate that the deposits have a nanocrystalline type of structure—there are regions with atomic ordered arrangement in bulk material with the average size of 3–5nm. Carbon is present as chromium carbide within the coating and it is distributed uniformly inside of the deposit. The deposits under study exhibit particular electrochemical behavior (absence of the active dissolution range in acid solution). The hardness of these coatings does not differ noticeably from that typical of coatings obtained in Cr(VI)-based baths. The wear characteristics of the deposits from the proposed bath are somewhat better than in the case of a common hexavalent chromium bath.