Formation mechanism of electrical discharge TiC-Fe composite coatings

Murray, J.W.; Algodi, Samer J.; Fay, Mike W.; Brown, Paul D.; Clare, Adam T.

Abstract

Comparison of electric discharge (ED) processed single deposit and continuum TiC-Fe cermet coatings, formed from a sacrificial powder metallurgy TiC tool electrode at negative polarity, on 304 stainless steel, provided insight into the ED coating (EDC) formation mechanism. A deposit from a single spark event was dominated by TiC, phase separated from a ∼2 wt% Fe matrix, with strongly aligned grains and banded microstructure, indicative of solidification from the coating/substrate interface. Conversely, a continuum coating, subjected to ∼200 spark events per location, exhibited a more complex, banded microstructure, with a mixture of equiaxed and columnar TiC grains within a ∼30 wt% Fe-based matrix, along with some concentrations of carbon from the oil dielectric. It is considered that each sparking event remelts previously solidified coating material, with or without further TiC particle incorporation, leading to gradual TiC dilution and the development of a TiC-Fe composite coating with increasing levels of substrate material forming the matrix.

Citation

Murray, J., Algodi, S. J., Fay, M. W., Brown, P. D., & Clare, A. T. (in press). Formation mechanism of electrical discharge TiC-Fe composite coatings. Journal of Materials Processing Technology, 243, https://doi.org/10.1016/j.jmatprotec.2016.12.011

• Journal Article Type: Article
• Acceptance Date: Dec 15, 2016
• Online Publication Date: Dec 16, 2016
• Deposit Date: Jan 12, 2017
• Publicly Available Date: Jan 12, 2017
• Journal: Journal of Materials Processing Technology
• Print ISSN: 0924-0136
• Electronic ISSN: 0924-0136
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• Volume: 243
• DOI: https://doi.org/10.1016/j.jmatprotec.2016.12.011
• Keywords: EDM, Electrical discharge coating, TEM, Crystal growth, Metal matrix composite, Titanium carbide
• Public URL: http://eprints.nottingham.ac.uk/id/eprint/39806
• Publisher URL: http://www.sciencedirect.com/science/article/pii/S092401361630454X
• Copyright Statement: Copyright information regarding this work can be found at the following address: http://creativecommons.org/licenses/by/4.0