Evolution of hard Fe–C electrodeposits with temperature

ABSTRACT

The high microhardness of electrodeposited Fe–C coatings with around 800 HV after electrodeposition increased to about 1300 HV by dedicated annealing, reflecting a huge potential for surface engineering. The coatings remain nanocrystalline during annealing, but co-deposited carbon and oxygen result in temperature-induced phase transformations. Energy-dispersive synchrotron diffraction revealed that carbides and oxides form during annealing of the as-deposited coating, which consisted mainly of carbon-free ferrite. The understanding of occurring precipitations was supplemented and verified by in-situ thermal analysis, which revealed the temperatures of thermal events related to decomposition reactions, the evolution of gasses and associated mass changes during annealing.

KEYWORDS:

• X-ray diffraction
• coating
• nanocrystalline
• annealing
• phase transformations
• electrodeposition
• iron-carbon
• hardened

Acknowledgements

The authors are grateful to Christoph Genzel, Manuela Klaus and Daniel Apel (HZB, Germany) for experimental support at the beamline EDDI of BESSY II. Flemming Bjerg Grumsen (DTU, Denmark) is acknowledged for TEM analysis and Thomas Lundin Christiansen (DTU, Denmark) is acknowledged for discussions on thermal analysis.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

The financial support by OCAS NV, ArcelorMittal Global R&D Gent (Belgium), a. h. nichro Haardchrom (Denmark) and Fast Track – Societal Partnership (Denmark), funded by the Innovation Fund Denmark (IFD), is kindly acknowledged.