Microstructural Characterization and Electrochemical Corrosion Behavior of TiO _x Coatings Prepared by Anodization and Magnetron Sputtering

ABSTRACT Titanium alloys are susceptible to localized corrosion in fluoride environments. This study compares TiO 2 coatings fabricated by anodic oxidation and magnetron sputtering for corrosion protection. The anodized film is porous and nonuniform; the sputtered TiO x coating exhibits a dense, nanocrystalline structure (avg. grain: ~62 nm), high adhesion ( L c : 3.85 N), and stable friction coefficient (0.18). Electrochemical tests show the sputtered coating significantly outperforms the anodized film and substrate: lower corrosion current density (0.197 μA·cm − 2 ), higher corrosion potential (0.151 V). Under potentostatic conditions (cathode, 0.6 V), it maintains the lowest steady‐state current density (0.184 μA·cm − 2 ). EIS reveals its charge transfer resistance (5.445 × 10 5 Ω·cm 2 ) greatly surpasses the anodic film (4.961 × 10 3 Ω·cm 2 ) and substrate (2.549 × 10 4 Ω·cm 2 ), confirming superior corrosion resistance. These findings aid durable coating design for titanium alloys in fluoride‐rich acidic media.