**4. Conclusions**

This study analyzed the corrosion resistance of the oil impregnated AAO surface of aluminum 7075 to sugges<sup>t</sup> a way to improve the corrosion protection for subsea application. The cylindrical shape was investigated as well as the plate shape. The contact angle was measured, and the interfacial tension between the water and the surfaces were calculated using the proposed equations. The salt spray test was conducted in the case of the plate shape, whereas the pressure test was carried out in the case of the cylindrical shape. Although salt spray and pressure tests were conducted, the oil in the pores of the AAO surface remained. The contact angle of the oil impregnated AAO surface was increased after the salt spray and pressure tests. That is, the nanoporous structure and the remaining oil in the pores help to maintain a high contact angle. The calculated interfacial tension coincided with the measurement of the contact angle. Corrosion was not indicated in the oil impregnated AAO surface for the 720 h salt spray test. The impregnated oil in the pores can endure a high-pressure condition (600 bar). Enhanced aluminum 7075 by AAO and oil impregnation can be used for subsea equipment.

**Author Contributions:** Conceptualization, J.-Y.J.; Methodology, J.C.; Validation, S.L.; Formal Analysis, Y.S.; Writing—Original Draft Preparation, Y.S.; Writing—Review & Editing, J.-Y.J.

**Funding:** This research was supported by a gran<sup>t</sup> from the Endowment Project of "Development of the Surface Modification Technologies based on Metal-Oxide for Offshore Equipment" (PES9320) and "Development of Technology to Support the Rapid Search and Rescue of Marine Accidents" (PES3130) funded by Korea Research Institute of Ships and Ocean Engineering.

**Conflicts of Interest:** The authors declare no conflict of interest.
