Surface enhancement by micro-arc oxidation induced TiO2 ceramic coating on additive manufacturing Ti-6Al-4V

This study investigates the utilization of micro-arc oxidation (MAO) TiO 2 ceramic coating for the enhancement of surface quality of Ti-6Al-4V (TC4) samples manufactured through selective laser melting (SLM) and selective electron beam melting (SEBM). Prior to treatment with the MAO process in a Na 2 SiO 3 system solution at various voltages, the samples were pre-polished to eliminate adhesion powders. The study systematically compares and assesses the surface roughness and corrosion resistance of as-built TC4 samples with MAO TiO 2 ceramic coating. The outcomes indicate that the combination of pre-polishing and MAO surface treatment decreases the surface roughness of SEBM samples from 13.386 μm to 9.343 μm. By contrast, this two-step surface treatment leads to an increment in surface roughness for SLM samples due to their initial low values and the porous nature of surface coating with high roughness. Furthermore, the MAO treatment considerably enhances the corrosion resistance of the original samples. Specifically, the corrosion current density Icorr of SLM samples decreases from 10.37×10 -7 A/cm 2 to 6.89×10 -7 A/cm 2 (420 V), and that of SEBM samples reduces from 8.013×10 -6 A/cm 2 to 1.672×10 -6 A/cm 2 (400 V). Therefore, MAO is an extremely effective surface treatment method that can considerably enhance the surface properties of TC4 produced through additive manufacturing.