Surface modification of biodegradable Mg alloy by adapting µ EDM capabilities with cryogenically-treated tool electrodes

Rahul Davis; Abhishek Singh; Kishore Debnath; Anup Kumar Keshri; Paulo Soares; Luciane Sopchenski; Herman A Terryn; Ved Prakash

doi:10.1007/s00170-023-11395-0

Surface modification of biodegradable Mg alloy by adapting µ EDM capabilities with cryogenically-treated tool electrodes

Int J Adv Manuf Technol. 2023;126(9-10):4617-4636. doi: 10.1007/s00170-023-11395-0. Epub 2023 Apr 23.

Authors

Rahul Davis¹, Abhishek Singh², Kishore Debnath³, Anup Kumar Keshri⁴, Paulo Soares⁵, Luciane Sopchenski⁶, Herman A Terryn⁶, Ved Prakash⁴

Affiliations

¹ Department of Mechanical Engineering, Vaugh Institute of Agricultural Engineering and Technology, Sam Higginbottom University of Agriculture, Technology and Sciences, Prayagraj, 211007 India.
² Department of Mechanical Engineering, National Institute of Technology Patna, Patna, 800005 India.
³ Department of Mechanical Engineering, National Institute of Technology Meghalaya, Shillong, 793003 India.
⁴ Department of Metallurgical and Materials Engineering, Indian Institute of Technology Patna, Patna, 801106 India.
⁵ Department of Mechanical Engineering, Pontifícia Universidade Católica Do Paraná, Curitiba, PR 80215-901 Brazil.
⁶ Department of Materials and Chemistry, Research Group Electrochemical and Surface Engineering, Vrije Universiteit Brussel, Brussels, Belgium.

Abstract

Biomaterials are engineered to develop an interaction with living cells for therapeutic and diagnostic purposes. The last decade reported a tremendously rising shift in the requirement for miniaturized biomedical implants exhibiting high precision and comprising various biomaterials such as non-biodegradable titanium (Ti) alloys and biodegradable magnesium (Mg) alloys. The excellent mechanical properties and lightweight characteristics of Mg AZ91D alloy make it an emerging material for biomedical applications. In this regard, micro-electric discharge machining (µEDM) is an excellent method that can be used to make micro-components with high dimensional accuracy. In the present research, attempts were made to improve the µEDM capabilities by using cryogenically-treated copper (CTCTE) and brass tool electrodes (CTBTE) amid machining of biodegradable Mg AZ91D alloy, followed by their comparison with a pair of untreated copper (UCTE) and brass tool electrodes (UBTE) in terms of minimum machining-time and dimensional-irregularity. To investigate the possible modification on the surfaces achieved with minimum machining-time and dimensional-irregularity, the morphology, chemistry, micro-hardness, corrosion resistance, topography, and wettability of these surfaces were further examined. The surface produced by CTCTE exhibited the minimum surface micro-cracks and craters, acceptable recast layer thickness (2.6 µm), 17.45% improved micro-hardness, satisfactory corrosion resistance, adequate surface roughness (R_a: 1.08 µm), and suitable hydrophobic behavior (contact angle: 119°), confirming improved biodegradation rate. Additionally, a comparative analysis among the tool electrodes revealed that cryogenically-treated tool electrodes outperformed the untreated ones. CTCTE-induced modification on the Mg AZ91D alloy surface suggests its suitability in biodegradable medical implant applications.

Keywords: Copper and brass tool electrodes; Dimensional-irregularity; Machining-time; Magnesium alloy; Micro-electric discharge machining; Surface modification.

© The Author(s), under exclusive licence to Springer-Verlag London Ltd., part of Springer Nature 2023, Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.