Influence of sodium aluminate concentration and process duration on microstructure, mechanical and electrochemical behavior of PEO coatings formed on CP-Ti.

Mixed titanium-aluminum oxide coatings were successfully grown on grade-2 commercially pure titanium substrates by using plasma electrolytic oxidation technique. The mechanical features and the resistance against corrosion were attributed to microstructural, morphological and surface changes resulting from different preparation conditions. The formation of bulk metal oxides consisting of a dominant TiAl 2 O 5 /Ti 2 Al 6 O 13 structure together with α-Al 2 O 3 and γ-Al 2 O 3 phases in the coatings accompanied by fully oxidized metal atoms on top of the surface showed a maximum 24.5 GPa hardness and 45 N adhesive critical load, respectively. Best corrosion performance of the coatings in 3.5% NaCl was found to be two orders of magnitude higher when compared to uncoated Ti. [Display omitted] • Preparation of PEO oxide layers on grade 2 CP-Ti by galvanostatic regime • Successfully grown titanium-aluminum mixed oxides on Ti substrates • Additional α-Al 2 O 3 and γ-Al 2 O 3 formation inside the coatings • Excellent adhesion and microhardness of coatings to the substrate • Superior corrosion resistance of PEO layers compared to pure Ti [ABSTRACT FROM AUTHOR]