Laser Sintered Ti-6Al-4V Alloy Coated with Plasma Electrolytic Oxidation: Influence of Duty Cycle and Frequency on Morphological, Structural, and Corrosion Properties

The effect of electrical process parameters like frequency and duty cycle on structural, morphological, and corrosion behaviour of nanocrystalline ceramic oxide coatings developed by plasma electrolytic oxidation (PEO) with pulsating DC power on laser sintered Ti-6Al-4V alloy is investigated in this study. Samples were coated with different combinations of frequency (1 kHz and 50 Hz) and duty cycle (90 and 20%). XRD patterns affirm that the coatings are predominantly comprised of anatase and rutile phases. The SEM analysis shows significant variation in pore size (2-10 µm) and thickness of coatings (10.1-13.2 µm). The high-frequency PEO coating exhibited a smoother surface. Overall, the findings suggest that duty cycle and frequency considerably impact pore morphology, surface roughness, and corrosion behaviour of laser sintered Ti-6Al-4V alloy coatings. The sample treated with 90% duty cycle and 1 kHz frequency reported three folds increase in corrosion resistance than the uncoated substrate.