Faculty Publications

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Laser surface melting of Mg-Zn-Dy alloy for better wettability and corrosion resistance for biodegradable implant applications
(Elsevier B.V., 2019) K.r, R.; Bontha, S.; M.r, R.; Das, M.; Balla, V.K.
In order to improve the performance of magnesium (Mg) for resorbable implant applications, Mg-1Zn-2Dy alloy was developed and the surface of the alloy has been modified by melting using lasers. Laser melted samples, at different laser energy density, were then subjected to microstructural, hardness, wettability and in-vitro degradation assessment. The microstructure of the Mg-Zn-Dy alloy mainly consisted of ?-Mg and eutectic phase (Mg 8 ZnDy). The melted region of the alloy surface evolved with fine grain microstructure at the near surface region and columnar grains near to the liquid solid substrate. The degree of grain size refinement obtained at the melted zone in the order of 1–2 ?m. The cross sectional microhardness of the modified zone was measured by Vickers microhardness tester. Due to these microstructural refinements and solid solution strengthening the surface hardness of laser treated alloy increased by two-fold. It was found that as the energy density increased the surface roughness along with the surface energy also increased. The wetting behaviour of the surface was estimated through measuring the contact angle by dropping the polar and non-polar liquid. Results showed that the surface energy is also found to change with LSM due to changes in the surface morphology, microstructure and chemical composition of the material. The detailed degradation study was carried out by immersing the samples in hanks balances salt solution (HBSS).The improvement in the degradation behaviour followed by laser surface melting is related to the microstructural refinement as a result of rapid heating and cooling of the melted zone. © 2019 Elsevier B.V.
Effect of Wire-EDM textures on corrosion performance of Bio-Degradable Mg alloy
(Elsevier B.V., 2024) Aswith Babu, I.; Kumar Manjhi, S.; Sekar, P.; Narendranath, S.; Balan, A.S.S.
Magnesium (Mg) is the most suitable material for biodegradable implant applications owing to its nontoxic behaviour and comparable Young's modulus to human bone. However, poor corrosion resistance limits its application. Therefore, surface texturing can be a more suitable and cost-effective technique to mitigate these issues. Hence, wire electric discharge machining (WEDM) is used to create various textures (wavy texture, microchannels, and micro-pillars) and investigate their influence on the corrosion resistance of Mg-Zn-Ca alloy. The results revealed that micropillar texture exhibited significantly lower surface roughness (Ra = 1.049 µm) and a higher contact angle indicative of hydrophobicity (130.3°), resulting in superior corrosion resistance (corrosion rate: 0.816 mm/year) compared to other textures and standard WEDM surfaces. These findings suggested that textured surfaces generated through WEDM hold the potential for enhancing the corrosion resistance of biodegradable Mg implants. © 2024 Elsevier B.V.
Investigating the role of WEDM surface texturing in the degradation and biocompatibility of Mg–Zn–Ca alloy
(KeAi Publishing Communications Ltd., 2025) Aswith Babu, I.; Sekar, P.; Prabhu, A.; Narendranath, S.; Balan, A.S.S.
Magnesium (Mg) alloy-based biodegradable implants are gaining popularity for their low density, high strength, and biocompatibility. The corrosion and wear performance of Mg is poor in physiological environments, leading to premature failure. Surface modification, particularly through surface texturing, reduces the effective contact area of Mg–Zn–Ca alloy with corrosive media and tribological partners, potentially optimizing its degradation kinetics and cytocompatibility. Wire Electric Discharge Machining (WEDM) offers a stable oxide layer on the surface, unlike laser surface texturing, which may thermally damage the Mg alloy. In this study, three types of textures, mainly Wavy Texture (WT), microchannels (MC), and micropillars (MP), were created using WEDM on the Mg–Zn–Ca samples, and their corrosion, wear, cytotoxicity, and cell adhesion performance were evaluated. Texturing on the surface of the samples enhanced the corrosion performance, from 3.14 mm/year for the untextured sample to 0.98 mm/year for the micropillar textured sample, representing a 68.8 % reduction. This improvement after texturing is attributed to the superior surface finish (1.049 ?m) and increased hydrophobicity (130.3°), equating to a 50.8 % improvement. The coefficient of friction (COF) value decreased from 0.364 for an untextured sample to 0.208 for microchannels, a 42.9 % reduction, due to the entrapment of debris in the textures and effective heat transfer. The samples' cell adhesion and cell viability have been improved after texturing. The combination of cytocompatibility, appropriate mechanical properties, and a reduced bio-corrosion rate highlights the potential of this surface texturing method, utilizing WEDM, as a promising approach to enhance biodegradable implant materials. © 2025 The Authors. Publishing services by Elsevier B.V. on behalf of KeAi Communications Co. Ltdé This is an open access article under the CC BY license. http://creativecommons.org/licenses/by/4.0/

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