Influences of alloyed Si on the corrosion resistance of Co–Cr–Mo alloy to molten Al by iso-thermal oxidation in air. (November 2015)

• Record Type: Journal Article
• Authors: Tunthawiroon, Phacharaphon; Li, Yunping; Chiba, Akihiko
• Is Part Of: Corrosion science. Volume 100(2015)
• Page Start: 428
• Page End: 434
• Publication Date: 2015-11
• Subjects: A. Cobalt -- B. SEM -- C. Interfaces -- C. Oxide coatings; Corrosion and anti-corrosives -- Periodicals; 620.11223
• DOI: 10.1016/j.corsci.2015.08.014
• Languages: English
• ISSNs: 0010-938X

Abstract

Graphical abstract: Highlights: Si addition improved the formation of smooth Cr2 O3 film. Si enhanced the corrosion resistance of alloy to molten Al. Si-rich layer retarded the expansion of corrosion areas. Co-29Cr-6Mo alloy with added Si is appropriate for use in Al die casting. Abstract: The corrosion resistance of Co–Cr–Mo alloys with various Si concentrations after oxidation to molten Al was investigated. Si was helpful in forming a more homogeneous, compact Cr2 O3 film after oxidation. Correspondingly, the Cr2 O3 -dominant film was more effective in enhancing the corrosion resistance than the duplex film of CoO and Cr2 O3 of alloy with low Si concentration. In addition, local defects such as the cracks acted as initiation sites of failure in oxide film. Ascribed to its higher stability, Si-rich layer beneath the oxide film delayed the reaction between Al and matrix even after the failure of oxide film.