Enhanced abrasive-mixed-µ-EDM performance towards improved surface characteristics of biodegradable Mg AZ31B alloy

Abstract

The non-degradable metallic implants, such as bone screws, often act as the source of dysfunction and harmful corrosion products in the aqueous environment inside the human body. Many of these implants are fixed either temporarily or permanently into the human body, and therefore, both need to match tight tolerances with a remarkably finished surface to eradicate burrs or striations. In this regard, the new generation of degradable magnesium (Mg) alloy implants with excellent osseointegration and low elasticity (like that of human bone), minimizing stress shielding, have been identified as potential candidates to challenge surgical procedures reintervention. However, the biological response of an implant toward the cells in vivo can be predominantly regulated by modifying the surface chemistry, morphology, and corrosion characteristics. Powder or abrasive-mixed-micro-electric discharge machining (A-M- µ -EDM) is gaining attention for executing precision machining and achieving a simultaneous surface modification on micro-manufactured surfaces, suitable for clinical applications. Therefore, the present research aimed at improving the surface characteristics of Mg AZ31B alloy via an augmented performance of A-M- µ -EDM by adopting copper and brass-micro-electrodes (C- µ -E and B- µ -E) in association with distinct abrasive particle concentrations (APCs: 0, 1.5, 3, 4.5, and 6 g/l) of bioactive zinc abrasives. To enhance the A-M- µ -EDM capabilities, the experiments were designed with a one-variable-at-a-time (OVAT) strategy, and the trial runs were conducted using different combinations of µ -electrodes and APCs. The superior performance of A-M- µ -EDM was noticed with the fusion of C- µ -E and 3 g/l APC in terms of minimum machining time (MT) and dimensional deviation (DD). The additional outcomes of this work reported favorable improvements in surface morphology, chemistry, topography, wettability, microhardness, and corrosion resistance on the A-M- µ -EDMed sample of interest.

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

“…Therefore, a few studies have proposed the addition of conductive abrasive particles to EDM (AM-EDM) to substantially lessen the structuring of micro-cracks on the processed Mg alloys. For instance, as outlined by two recent experimental investigations, Zn-abrasive-assisted µ EDM minimized the surface micro-cracks and thus achieved remarkable surface modification in terms of superior corrosion resistance on Mg alloys over the unmachined specimen [ 18 , 30 ]. However, it can be argued that the studies on AM-EDM of Mg alloys suffered from certain weaknesses, such as excess thickness and inadequate uniformity of recast layer, which resulted in the poor surface quality of Mg alloys [ 31 , 32 ].…”

Effect of the Cryogenically Treated Copper Nozzle Used in Plasma Arc Machining of S235 Steel

“…Te analysis revealed that the cryogenic treatment would reduce electrode wear and improve MRR. Davis stated that [8] cryogenic treatment reduced adhering particles, micropores, and cracks on the surface of the sample. Davis and Singh stated that [9] powder or abrasive-mixed-microelectric discharge machining (A-M-EDM) is gaining popularity for performing precise machining and simultaneously modifying micromanufactured surface tables for clinical applications.…”