Surface modification of ductile iron produced by an innovative in-situ casting technique

ABSTRACT

In this study, a chromium carbide layer was fabricated by an in-situ casting technique on ductile iron cast components. The procedure consists of (i) applying a ferrochrome slurry at the surfaces of silica sand moulds to create a surface layer (e.g. coating) and (ii) use a ductile iron alloy to cast the coated moulds. The microstructure of the realised surface layer was characterised and analysed via Scanning Electron Microscopy (SEM), optical microscopy (OM) and X-ray Diffraction (XRD).The corrosion behaviour of the samples was analysed by an electrochemical method using 0.03 M NaCl. The wear tests and Vickers hardness measurements were performed to determine the properties of the surface layer. It was determined that the layer is composed of chromium carbide (Cr₇C₃), ledeburite and pearlite. The ‘chromium carbide’constituent improved significantly both the wear resistance and the hardness of the surface layer. Electrochemical measurements have indicated that the carbide-based layer exhibits a lower corrosion resistance than the substrate (e.g. casting).

KEYWORDS:

• Wear resistance
• electrochemical test
• in-situ surface modification
• ductile iron

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

Financial support from the Basque Government (Project: FRONTIERS II: Superficies multifuncionalesen la frontera del conocimiento, ELKARTEK 2016 KK-2016/00093) is gratefully appreciated.