Investigation of the Machining, Structural and Antibacterial Properties on Ti6Al4V Alloy by PMEDM: Taguchi Optimizing the İnfluence of HA, Hbn And HA/Hbn Doping

Abstract

This study systematically investigates the individual and combined effects of hydroxyapatite (HA) and hexagonal boron nitride (hBN) nanopowders as dielectric additives during PMEDM processing of Ti6Al4V alloys, providing comparative insights into their influence on surface integrity, mechanical performance, and antibacterial properties. In this context, X-ray diffraction (XRD), optical and scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), surface roughness (SR), contact angle measurements were used to characterize the structural and morphological properties of the samples on the surface and subsurface. Powder additives were deposited onto the surfaces of the samples using different processing parameters during the EDM process, and XRD and EDS results revealed the presence of HA and hBN phases. In this regard, the surface roughness values varied between 2.03 μm and 3.97 μm on average, depending on the discharge current, pulse duration and the different powder ratios added to the dielectric liquid. In addition, while the cratered structures formed on the surfaces of the samples processed after EDM reduce the surface wettability, the best wettability was observed on the surface processed with a discharge current of 9 A, a pulse duration of 200 μs, and the addition of 15 g/l hydroxyapatite (HA) powder. In order to correlate processing performance with the effect of added dust concentrations on biofilm, cellular adhesion and proliferation were examined with Staphylococcus aureus bacterial strain at 2, 4, and 6 h. This showed that a 5 g powder additive promoted cellular activity growth, while a 10 g concentration inhibited it, except for HA/hBN particles. Extending exposure to 15 g further confirmed biofilm formation, highlighting the complexity of bacteria adhesion