Constructing surface micro/nano structures and preparing nano-coatings could endow the material surface with special performance. In this work, the special functions of surface micro/nano structures, as well as the main methods and processing technologies for preparing surface micro/nano structures and nano-coatings were mainly reviewed. Firstly, the applications of surface micro/nano structures in superhydrophobicity, optical superlens, friction and wear were introduced. Secondly, the research progress of lithography technology, laser processing technology, self-assembly technology, additive manufacturing technology (3D printing), processing methods of surface micro/nano structures and nano-coatings, such as deposition method and sol-gel method, was described, respectively. Finally, the problems and development trend of different preparation methods of surface micro/nano structures and nano-coatings were summarized.

Functional nano-coatings have been a research hotspot in recent years. The nano-size composition units provide good volume effect and surface effect for functional nano-coatings, and greatly optimize the mechanical properties, corrosion resistance, oxidation resistance and wear resistance of the coatings. The preparation technology and properties of functional nano-coatings determine the application range of nano-coatings. However, most reviews focus on certain properties, preparation methods or applications of functional nano-coatings, and lack of reviews on the integrity of functional nano-coatings. Firstly, this work introduced the concept and classification of functional nano-coatings briefly. Secondly, the preparation techniques of functional nano-coatings were described in detail, including traditional chemical vapor deposition, physical vapor deposition and sol-gel method, the latest plasma spraying technology and other preparation techniques. Moreover, the principles, advantages and disadvantages of various nano-coatings preparation technologies and the application of nano-coatings in materials were analyzed and summarized. Finally, the latest and popular applications of functional nano-coatings were reviewed in detail, and the application prospect and potential of functional nano-coatings were prospected.

As a new spraying method, suspension plasma spraying (SPS) can prepare biological coatings with uniform microstructures and few defects. In the paper, the principle of hydroxyapatite (HA) nano biological coatings prepared by SPS was introduced. The formation mechanisms of structure of sintering zones and densification zones were summarized, and the droplet evolution of the suspension during flight was analyzed. The effects of process parameters on HA biological coatings by SPS were discussed, and the deposition mechanisms of HA coatings were revealed. Besides, the mechanical properties, antibacterial properties, cell compatibility and in vitro bioactivity of HA coatings prepared by SPS were summarized.

In a cold and high humidity environment, ice and frost are easy to condense on the surfaces of aircraft, railway transportation, wind turbine blades, transmission lines and other equipment, thus reducing work efficiency, affecting the proper use of equipment, and causing huge security risks. Therefore, how to effectively delay the formation of frost on the surfaces of solid materials and promote the removal of ice has become a research hot topic in the field of high-performance materials. Conventionalde-icing methods including mechanical, chemical, and thermal de-icing have the problems of high energy consumption, excessive de-icing waste liquidlow de-icing efficiency, and easy to damage the surface of equipment, which are contrary to the sustainable development concept of “green, environmental protection, high efficiency and energy saving”. Inspired by natural biology, researchers have developed some new passive superhydrophobic anti-icing technologies, which have the advantages of low cost, low energy consumption and excellent anti-ice performance, and perform high application prospect. In this paper, for the new superhydrophobic anti-icing materials, the theoretical progress of superhydrophobic wetting of solid surfaces and the icingand anti-icing mechanism of solid surfaces were reviewed. The top-down preparation methods (laser etching, chemical etching, template method, etc.) and bottom-up preparation methods (coating technology, magnetron sputtering technology, sol-gel technology and electrodeposition technology, etc.) of superhydrophobic anti-icing surface were summarized. Finally, the limitations of superhydrophobic anti-icing materials were discussed, and their application prospect and development trend were forecasted.

For improving the surface hardness and high temperature friction wear properties of Inconel 718 alloy, CrAlN/CrN coating was prepared on the alloy surface by multi-arc ion plating technique. The microstructure and mechanical properties of the coating were analyzed and characterized using X-ray diffractometer (XRD), X-ray photoelectron spectrometer (XPS), scanning electron microscopy (SEM), nanoindentation and scratching instruments. In addition, the friction properties of the coating were tested at room temperature, 350 ℃ and 650 °C using a UMT friction and wear tester, and the morphological characteristics, elemental distribution and physical phases of the wear marks were analyzed to discuss the friction and wear mechanisms of coatings at different temperatures. Results showed that the nano-multilayer CrAlN/CrN coating with dense microstructure was mainly composed of face-centered cubic CrN phase, which presented a selective orientation of (200) crystal plane. The CrAlN/CrN coating had good mechanical properties on the surface of Inconel 718 alloy with hardness and bonding force of (29.3±1.2) GPa and 70.4 N, respectively. Meanwhile, the coating had excellent wear resistance at room temperature and 350 ℃, with wear rates as low as 1.5×10^-6 mm³/(N·m) and 1.7×10^-6 mm³/(N·m), respectively, and the dominant wear mechanisms were abrasive wear and fatigue wear respectively. At 650 ℃, the coating reached the lowest coefficient of friction (0.33), but the wear rate increased, mainly in the form of abrasive wear.

In order to prolong the service life of magnesium alloy, a stable superhydrophobic coating was prepared on AZ31b magnesium alloy substrate by spraying method. Firstly, an epoxy resin bonding layer was coated on the surface of substrate, and micron SiO₂ particles were sprayed on the epoxy resin bonding layer to construct a micron framework. Subsequently, nano polytetrafluoroethylene particles were sprayed to provide hydrophobic particles. The prepared superhydrophobic coating had a contact angle of ~157.40° and sliding of only 2°. Results showed that the superhydrophobic coating had excellent chemical and mechanical stability, good corrosion resistance, self-cleaning and anti-fouling properties.

In order to meet the application requirements of polymer composite coating under high temperature conditions and promote the practical application of polymer organic composite coating in the field of high temperature protection, polyimide (PI) was selected as the resin matrix, and the heat resistance was modified and enhanced by adding nano-Si₃N₄. Moreover, the effects of silane coupling agent KH550 and different content of Si₃N₄ on the surface state and heat resistance of the coating were studied. Results showed that the glass transition temperature (T_g) of the composite coating with 10% (mass fraction) Si₃N₄ increased to 495 ℃, which was higher than that of pure PI coating (483 ℃). After the addition of KH550, on one hand, KH550 introduced amino functional groups on the Si₃N₄ surface to cross-link it with the PI molecular chain; on the other hand, KH550 directly interacted with PI molecules to enhance the viscosity of the coating, so that the dispersion of Si₃N₄ and the binding force of the coating and the substrate were significantly improved. Besides, the PI composite coatings with different contents of Si₃N₄ were prepared for comparison, and it could be found that the PI composite coating with 10% Si₃N₄ exhibited the optimal heat resistance and surface quality.