Characterization of ta-C film on micro arc oxidation coated titanium alloy in simulated seawater

The harsh marine environment puts forward higher performance requirements for titanium alloy parts, and it is urgent to develop advanced surface protection technology. In this paper, micro arc oxidation (MAO)/tetrahedral amorphous carbon (ta-C) composite coatings were fabricated via MAO processing and filtered cathodic vacuum arc (FCVA) system on TC4 titanium alloy. The surface morphologies, tribological properties and corrosion resistance in simulated seawater of the coatings were investigated. The results showed that, compared with the monolayer of MAO coating or ta-C film, the MAO/ta-C composite coating still showed porous characteristics and had an improved bonding force. Due to compact oxide ceramic coating of MAO coating and self-lubrication of taC film, the MAO/ta-C composite coating had the lowest friction coefficient (0.13) and width of wear scar (356.84 um) in all samples. The lowest corrosion current density (8.321 x 10-9 A/cm2) and highest corrosion potential (-0.012 V) in the simulated seawater solution confirmed the most effective corrosion protection provided by the MAO/ta-C coating. These research results could provide important support for promoting the application of titanium.