With the development of nanotechnology, the combination of nanotechnology and coating technology can leverage its comprehensive advantages to achieve excellent mechanical, thermal, and electromagnetic properties of materials, meeting the needs of structural performance (strength, toughness, etc.) and environmental performance (wear resistance, corrosion resistance, high temperature resistance, etc.). Nano ceramic coatings have special physical and chemical properties, making them exhibit characteristics in terms of functional protection that conventional materials do not possess. Therefore, nano ceramic coatings have broad application prospects in thermal insulation, anti-corrosion and rust prevention, insulation protection, self-cleaning and anti fouling, absorption and energy conservation, sealing and high temperature resistance, etc.

fracture toughness

Fracture toughness is a performance indicator that reflects the resistance of materials to crack instability and propagation. There is a two-phase structure composed of matrix phase obtained by melting and solidification of nanoparticles and incompletely melted nanoparticles in nanoceramic coatings. When cracks extend to the interface between unmelted or semi melted particles and the matrix phase, these particles not only absorb crack propagation energy, but also have the effect of preventing and deflecting crack propagation. In conventional ceramic coatings, the bonding between layered structures is poor, and cracks are easy to propagate along the layers. Therefore, the toughness of nano ceramic coatings is better than that of conventional ceramic coatings.

hardness
Hardness is one of the important performance indicators of ceramic coatings.
The hardness of nano coatings has a low dependence on the heterogeneity of spraying process parameters and coating structure. The refinement of grain size results in a significantly higher hardness of nano ceramic coatings than that of micro ceramic coatings.
Wear resistance
The improvement of hardness and toughness of nanostructured coatings is the main reason for the improvement of wear resistance. During the wear process of nano ceramic coatings, there may be shear of micro convex bodies or incomplete melting of particles at pores that detach from the coating surface. These small particles disperse in the lubricating oil film between the coating and the friction part, playing a "micro bearing" role, reducing the friction coefficient of the coating and improving wear resistance.
Bond strength
The bonding strength of ceramic coatings includes the interface bonding strength between the coating and the substrate, as well as the bonding strength of the coating itself. The release effect of unexpanded interlayer cracks on residual stress in the coating and the higher flight speed of nanostructured feed during the spraying process are beneficial for improving the bonding strength compared to ordinary powders. After spraying nano powder, the melting state of particles can be improved, resulting in a significant reduction in coating pores, and some of the pores are located inside the deformed particles, which helps to improve the bonding strength of the coating.

porosity
Appropriate coating pores are beneficial for lubricating friction and high-temperature insulation workpieces, but harmful for corrosion resistance, high-temperature oxidation resistance, and high-temperature erosion resistance workpieces. Research has found that porosity is related to flame temperature and velocity; It is also related to particle velocity, and as the particle velocity increases, there is a downward trend in porosity.
Thermal conductivity
Thermal conductivity is the main performance indicator of thermal barrier coatings, which decreases with decreasing grain size. As the grain size decreases, the micro interfaces inside the coating increase and the interface distance decreases, resulting in a decrease in the average free path of particles during the heat conduction process and a decrease in the material's thermal conductivity.