Low voltage environmentally friendly plasma electrolytic oxidation process for titanium alloys

Abstract

Plasma electrolytic oxidation (PEO) is a surface-treatment process extensively used to protect the surfaces of light metals such as Mg, Al, and Ti. Here, we report an environmentally friendly PEO process that uses nitrogen-containing electrolytes and low voltages (120 V) to form ~ 12 micron thick, uniform, adherent and porous oxide coatings on T1 titanium alloy surfaces. We evaluated the influence of nitrogenation by comparing the coatings to alloys treated in PEO baths without nitrogen-containing compounds. Both sets of samples exhibited basalt-like morphologies with distinct variation in the pore structures. The composition analyses showed that the coatings were primarily composites of titanium oxides and silicates. The T1 Ti alloys treated with nitrogen-containing electrolytes also contained TiC and TiN. This is the first ever report of producing TixOy, Ti–Si–O, TiC, and TiN composite coatings using a single PEO bath without carbide/nitride nanoparticles. The bandgaps of the coatings suggested visible light functionality. The use of nitrogen-based compounds in the PEO baths improved the hardness of the oxide layers but introduced stress-induced cracking which are potentially responsible for the reduction in corrosion resistance of the nitride and carbide containing coatings.

Antibacterial Coatings for Titanium Implants: Recent Trends and Future Perspectives

“…To enhance antibacterial activity and create a favorable healing environment, inorganic biofunctional metal ions [ 34 ], nanoparticles [ 35 ], and non-metals like iodine [ 36 ] and fluorine [ 37 ] are incorporated into the titanium surface. The incorporation is done either directly or by modifying the titanium surface through various methods, e.g., electrochemical treatment, plasma ion implantation [ 38 ], plasma electrolytic oxidation [ 39 ], sol-gel [ 40 ], micro-arc oxidation [ 28 ], etc. The antibacterial nature of these agents is often dictated by the appropriate concentration of the ions and their release into the surrounding tissues [ 34 ].…”

Synthesis of nanofibrous chitosan/Fe3O4/TiO2@TiO2 microspheres with enhanced biocompatibility and antibacterial property

“…In addition, for Ti 2p (Figure 3C), the two obvious binding energies centered at 458.28 and 463.98 eV are normally assigned to the Ti 2p3/2 and Ti 2p1/2 peak of anatase/rutile‐type TiO 2 23–26 . The peak at 471.48 eV should be attributed to satellite feature typical of titanium oxides 27 …”

“…[23][24][25][26] The peak at 471.48 eV should be attributed to satellite feature typical of titanium oxides. 27 Figure 4 shows FT-IR spectra of chitosan, TiO 2 NPs, Fe 3 O 4 NPs, and ChFeTi and ChFeTi@TiNW microspheres. Chitosan had two absorption bands at 2927 and 2855 cm −1 for CH 2 -groups and the wide peak at 1540 cm −1 for NH 2 groups.…”

Characteristics of Hydroxyapatite-Modified Coatings Based on TiO2 Obtained by Plasma Electrolytic Oxidation and Electrophoretic Deposition

“…The SEM micrographs from Figure 2 show the complex porous surface of the oxidized titanium samples in different stages. According to the PEO process mechanism described in the literature [ 5 ], initially, at low voltage values, a uniform, dense, and thin (nano-scaled) oxide layer is formed on the surface of the samples. As soon as the applied voltage reaches the breakdown potential of the previously formed film, various sparking phenomena appear, leading to the formation of discharge channels, where temperature and pressure achieve higher values and different processes, such as melting and oxidation, may occur.…”

“…Still, once high contact loads are applied combined with reducing or low oxygen environments, the native oxide film may be rapidly damaged, promoting galvanic or crevice corrosion. Consequently, several superficial treatment processes are frequently applied to enhance surface characteristics [ 3 , 4 ], including physical vapor deposition, thermal oxidation, plasma spraying, anodizing, or plasma electrolytic oxidation (PEO) [ 5 ]. Moreover, the tribological behavior of Ti-based materials can be significantly improved by applying an appropriate surface modification strategy [ 6 ].…”