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A new approach was adopted to improve the corrosion behavior of the chromium nitride (CrNx) hard coating through magnetron sputtering deposition at different nitrogen flow rates. The influence of the nitrogen flow rates on the chemical composition, microstructure, mechanical property and corrosion behavior in artificial seawater of the CrNx coatings was investigated. The results show that with the increase of the nitrogen flow rates, the growth structure of the coatings varied from dense granular growth to coarse columnar growth. Increasing the nitrogen flow rates was helpful to decrease the Cr/N ratio and induce the phase transforming from mixed hexagonal Cr2N and face-centered cubic CrN to single CrN. However, the coatings under different nitrogen flow rates significantly improved the corrosion resistance and hardness of the steel substrate. Furthermore, at high nitrogen flow rate, the coating had high corrosion velocity and low protective capability against the substrate corrosion due to the fast corrosion channels acted by the columnar grain boundaries. While at the middle nitrogen flow rate, the coating with CrN phase, densely granular growth structure and moderate grain size resulted in excellent corrosion resistance and highest hardness. [ABSTRACT FROM AUTHOR]

The lack of durability in superhydrophobic coatings has restricted the practical applications of coatings in the fields of marine and construction. In this paper, the composite coatings of epoxy resin (EP), polydimethylsiloxane (PDMS) and SiO 2 nanoparticles were prepared by using the room-temperature liquid spraying and laser curing methods. The effects of the laser curing powers on the microstructure, hydrophobicity, durability in terms of corrosion and friction of the coatings were researched. The results demonstrate that there were micropores and aggregated SiO 2 nanoparticles on the surface of coatings. The coatings had the growth structure with SiO 2 nanoparticles partially embedded into the PDMS and EP bottom layer, and PDMS in the bottom layer migrating upward. With the increase of laser curing powers, the nanoparticles gathered significantly and the micropores was decreased. Under different laser curing powers, the coatings had the Si-(CH 3) 2 hydrophobic group and exhibited superhydrophobicity. All the coatings showed excellent self-cleaning performance in muddy water and ink. As the laser curing power increased, the superhydrophobicity of the coating was increased (the maximum contact angle of the coating was up to 161.90 ± 1.85°). Moreover, the coatings had strong corrosion resistance after being immersed in artificial seawater for 72 h. The coatings still had the superhydrophobicity after 100 cycles of load friction. With the increase of laser curing power, the friction resistance of the coating was improved, and the corrosion resistance was first improved and then reduced. This study provides a new idea for obtaining superhydrophobic and strong durable coatings. [Display omitted] • Laser curing was effective applied to improve durability of EP + PDMS/SiO 2 coatings. • All the coatings exhibit superhydrophobic and self-cleaning performances in sewage. • Coatings still exhibit superhydrophobicity after 100 cycles of 200 g load friction. • Superhydrophobicity and friction resistance improve by increasing laser curing power. • Coatings are strong corrosion resistance against artificial seawater exceed 72 h. [ABSTRACT FROM AUTHOR]