Corrosion Behavior Evaluation in Simulated Body Fluid of a Modified Ti–6Al–4V Alloy by DC Glow Plasma Nitriding

Abstract

DC glow discharge plasma nitriding is the process of surface hardening through the spread of nitrogen atoms to the metal surface under special conditions of the plasma nitriding. Titanium and titanium alloys are the most common alloys used in medical applications. Titanium and its alloys are lightweight, corrosion resistant, and have good fatigue properties but lack wear resistance under aggressive environments. The plasma nitriding process was used for a titanium alloy (Ti–6Al–4V) rod with different parameters at a vacuum chamber of air (2 mbar), 680 volts and 30 mA. The plasma nitriding process was performed at different nitriding times (5, 10, and 15 h), and the effect of plasma nitriding was examined on the chemical compassion of Ti–6Al–4V alloy and the appearance of phases was studied by optical microscopy (OM), scanning electron microscopy and field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), Tafel potential polarization, and cyclic polarization. The results indicate that the formation of layers and phases Ti₂N and Ti₂N_3−x on a surface of the alloy were achieved, which would improve the surface characteristics of chemical corrosion in simulated body fluid.