Inspired by the “Lotus Leaf Effect” in nature, the phenomenon of superhydrophobia has attracted tremendous attention from researchers. Due to their special surface wettability, the superhydrophobic surfaces have been found to have broad potential applications in the fields of marine engineering, medical equipment, and aerospace. Based on the introduction of the principles of wettability, the advantages and disadvantages of various preparation methods for superhydrophobic surfaces were studied and summarized in this paper. The research progress on superhydrophobic surfaces in marine engineering applications was analyzed according to their self-cleaning, anti-corrosion, heat transfer, drag reduction, anti-fouling, ant-icing, and oil/water separation properties. Finally, to advance practical applications, the current challenges associated with superhydrophobic surfaces are highlighted, and potential future development directions are proposed.

A composite ceramic coating containing h-BN particles was prepared on the ZL109 alloy via plasma electrolytic oxidation. The h-BN particles were modified by Polyethylene glycol to improve the dispersibility. The results revealed that the h-BN particles in the electrolyte were inertly incorporated into the coating. Meanwhile, the incorporation of h-BN particles can reduce the porosity and slightly increase the roughness of the composite ceramic coating. Furthermore, the growth rate of the coating and the conversion of γ-Al₂O₃ and α-Al₂O₃ were promoted by the incorporation of h-BN particles via the change of the current. In addition, due to the presence of h-BN particles, the composite ceramic coating had a lower friction coefficient and a lower wear rate under dry sliding condition.

Particulate pollutants mixed in hydraulic oil will lead to the failure of the marine hydraulic system. Nowadays, the current identification methods of particulate pollutants in oil make it challenging to obtain the specific parameters of pollutants. For this reason, this paper proposes a recognition method of marine-hydraulic-oil-particle pollutants based on OpenCV. The image of particles in the marine hydraulic oil was preprocessed by OpenCV software and using the Canny operator edge detection algorithm to extract the contour of particle pollutants to obtain their area and perimeter. The recognition accuracy reached 95%. Using the Douglas–Peucker algorithm for fit polygons, then image moments to obtain the angle-distance waveform of particulate pollutants, the shape of marine-hydraulic-oil particulate pollutants was successfully identified. The designed method has the advantages of fast calculation efficiency, high accuracy, and real-time detection of various parameters of particulate pollutants in marine hydraulic oil. It has great significance for the fault diagnosis of hydraulic systems and prolonging the working life of hydraulic equipment. This research provides a new idea for the condition monitoring and fault diagnosis of ships and offshore engineering equipment.

A fluorine-free cerium palmitate superhydrophobic surface on an aluminum plate was fabricated via a two-step electrodeposition method. The mechanical durability, anti-corrosion performance, water repellency and drag reduction properties were tested. The results indicate that a superhydrophobic surface with a densely packed convex island shape with micro-pores and nano-scale strips was formed on the aluminum plate. Furthermore, the as-prepared surface exhibits excellent water-repelling ability with a water contact angle of 162.3° and a sliding angle of 1.5°. Owing to the protective effect of the convex island structure on the surface, the surface also shows superb mechanical durability, which is a shortcoming of ordinary electrodeposited surfaces. Moreover, compared with bare aluminum, the corrosion inhibition efficiency of the superhydrophobic surface is 99.55% and the surface drag decreases by 65.3% at a lower flow rate. Therefore, it is believed that the environmentally friendly fluorine-free superhydrophobic surface has promising potential applications in marine engineering.