علي معصوم زاده

Titanium alloys are widely used in medical implants due to their excellent biocompatibility; however, their relatively low hardness an‎d limited corrosion resistance can reduce their service life. The aim of this study is to investigate the effect of different graphene oxide (GO) contents on the corrosion resistance of a titanium–hydroxyapatite–graphene oxide (Ti–HA–GO) nanocomposite coating deposited on a Ti–6Al–4V alloy by ElectroSpark Deposition (ESD) method. To this end, nanocomposite electrodes containing 70 wt% titanium an‎d graphene Oxide to hydroxyapatite (GO/HA) weight ratios of 0.2, 1, an‎d 5 were first prepared by spark plasma sintering (SPS), an‎d were then used as electrodes in the coating process. Coatings were applied via ESD at a constant duty cycle an‎d frequency, using three current limits 10, 12, an‎d 15 A for each electrode composition. The microstructure an‎d surface topography of the coatings were examined using scanning electron microscopy (SEM), the chemical composition was analyzed with energy-dispersive X-ray spectroscopy (EDS), an‎d phase analysis was performed by X-ray diffraction (XRD). The surface roughness of the coating was eva‎luated using a laser profilometer. A Vickers microhardness tester with a 0.98 N load was used to eva‎luate the surface microhardness. Corrosion behavior was eva‎luated by potentiodynamic polarization an‎d electrochemical impedance spectroscopy (EIS) in simulated body fluid (SBF). Ti–HA–GO Coatings with thicknesses of 16.5–38 μm were obtained on Ti–6Al–4V by 3-pass electrospark deposition. The average surface roughness (Ra) of the applied coatings was measured to be in the range of 5.28 to 7.48 μm. The obtained results showed that increasing the spark energy, as well as increasing the GO/HA ratio in the electrode, increases the fluidity of molten dro‎ps an‎d makes coating surface smoother. The surface microhardness of the coatings was obtained in the range of 672 ± 51 to 992 ± 41 HV, indicating a considerable increase compared with the substrate with a microhardness of 372 ± 8 HV. It was determined that the coating reduced the corrosion rate by up to 91% relative to the titanium substrate an‎d increased the polarization resistance by 3.5 times. XRD results showed the diffraction pattern of hydroxyapatite an‎d CaTiO₃ phases on the surface, an‎d on the other han‎d, the smoother surface produced by increasing the current limit led to a remarkable improvement in corrosion resistance.

مهندسي سطح , رسوب‌دهي جرقه الكتريكي , آلياژ Ti-6Al-4V , خوردگي , هيدروكسي‌آپاتيت , اكسيدگرافن , تف جوشي جرقه‌اي پلاسما

Surface engineering , Electrospark deposition , Ti-6Al-4V Alloy , Corrosion , Hydroxyapatite , Graphene Oxide , Spark plasma sintering

Ali Masoumzadeh

Hossein Aghajani - Seyed Hossein Razavi