SURFACE MORPHOLOGY AND MICROHARDNESS BEHAVIOR OF 316L IN HAP-PMEDM

The development of biomaterials for implants nowadays requires materials with superior mechanical and physical properties for enhanced osseointegration and sustained longevity. This research work was conducted to investigate the influence of nano hydroxyapatite (HAp) powder mixed electrical discharge machining (PMEDM) on surface morphology and microhardness of modified 316L stainless steel surface. The chosen process parameters were discharge current, pulse on/off duration and gap voltage in order to analyze the selected output responses. HAp concentration (15 g/l) along with reverse polarity was kept constant for current experimentation. The experimental results testified that surface morphology of PMEDM surface was significantly improved along with augmentation of 79% in microhardness (HV) of HAp modified surface of medical grade stainless steel. Furthermore, XRD and SEM characterization confirmed the deposition of calcium, phosphorous and inter-metallic compounds on HA-PMEDMed surface. The surface thus produced is expected to facilitate better bone-implant adhesion and bioactivity

EXPERIMENTAL INVESTIGATION OF OPTIMAL ED MACHINING PARAMETERS FOR Ti-6Al-4V BIOMATERIAL

The present study investigates optimal parameters for machining of Ti-6Al-4V using EDM with graphite electrode. Herein, another technique of modifying surface properties and enhancing machining rate using electrical discharge machining (EDM) was developed. In the present study, design of experiment (D.O.E) was developed using the Taguchi’s orthogonal array to examine the effect of the input machining factors on the machining characteristics, and to forecast the optimized EDM parameters in terms of peak current, pulse-on time, pulse-off time and applied gap voltage. Each experiment was performed to obtain a hole of 1mm depth on the workpiece. From the results, it is found that the discharge current has significant influence on material removal rate (MRR) and surface roughness (SR) followed by other selected parameters, i.e. pulse-on time, pulse-off time. The MRR augmented steeply with the current and was recorded as maximum at 4 Amps. In-vitro bioactivity test was conducted in the simulated body fluid to examine bioactivity confirming a significant apatite growth on the surface treated with ED sparks. The surface and chemical alteration were analyzed by using Scanning Electron Microscopy (SEM) and X-Ray Diffraction (XRD) along with the identification of the substantially enhanced morphology for clinical success

Enhancing Corrosion and Wear Resistance of Ti6Al4V Alloy Using CNTs Mixed Electro-Discharge Process

This paper presents wear and corrosion resistance analysis of carbon nanotubes coated with Ti-6Al-4V alloy processed by electro-discharge treatment. The reported work is carried out using Taguchi’s L18 orthogonal array to design the experimental matrix by varying five input process parameters i.e., dielectric medium (plain dielectric, multi-walled carbon nanotubes (MWCNTs) mixed dielectric), current (1–4 A), pulse-on-time (30–60 µs), pulse-off-time (60–120 µs), and voltage (30–50 V). The output responses are assessed in terms of microhardness and surface roughness of the treated specimen. X-ray diffraction (XRD) spectra of the coated sample reveal the formation of intermetallic compounds, oxides, and carbides, whereas surface morphology is observed using scanning electron microscopy (SEM) analysis. For the purpose of the in-vitro wear behavior of treated samples, the surface with superior microhardness values in plain dielectric and MWCNTs mixed dielectric is compared using a pin-on-disc type wear test. Furthermore, electrochemical corrosion test is also conducted to portray the dominance of treated substrate of Ti-6Al-4V alloy for biomedical applications. It is concluded that the wear-resistant and the corrosion protection efficiency of the MWCNTs treated substrate enhanced to 95%, and 96.63%, respectively