Tribo-corrosion behavior of WEDM-induced micro textured Mg-2Zn-Ca biodegradable alloy

Abstract

Magnesium (Mg) alloys offer significant potential use in biodegradable implants due to their exceptional biocompatibility and mechanical properties that closely resemble those of natural bone. Despite their promise for biodegradable implants, the rapid degradation and poor wear resistance of magnesium alloys lead to premature failure due to a wear-corrosion synergy. This research focuses on enhancing the surface quality and machining performance of Mg–2Zn–Ca alloy through Wire Electrical Discharge Machining (WEDM), aiming to develop micro-textures and assess their influence on tribo-corrosion resistance. A complete factorial design was employed to analyze how WEDM parameters, pulse on time (P_on), pulse off time (P_off), and servo voltage (SV), affect surface roughness (R_a), material removal rate (MRR), and corrosion rate (CR). Optimization was carried out using a combined Multi-Objective Genetic Algorithm (MOGA) and the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS), resulting in optimal values of R_a at 4.62 μm, MRR at 12 mm³/min, and CR at 3.6 mm/year. Based on these optimized settings, three distinct surface textures were produced, with the micro-pillar (MP) configuration demonstrating superior tribo-corrosion resistance by effectively capturing wear debris, improving lubrication, and facilitating the formation of a protective oxide layer. MP textures demonstrated a better open-circuit potential and reduced friction by 46.7% compared to untextured samples, which is linked to a refined microstructure and increased hardness (79.6 HV). These results suggest that WEDM-textured Mg–2Zn–Ca alloys offer controlled degradation and improved wear resistance for biodegradable implant applications.