Firstly, substrate surface pretreatment is the foundation for improving the adhesion of the coating. Before thermal spraying, it is usually necessary to carry out surface treatments such as degreasing, sandblasting, and roughening on the substrate. Among them, sandblasting treatment is particularly important, as it can remove surface oxides, oil污, and other impurities, while increasing the roughness of the substrate surface, providing an 'anchor' effect for the coating, enhancing mechanical interlocking, and thus significantly improving the adhesion of the coating.

　　Secondly, choosing appropriate spraying process parameters is crucial for improving adhesion. Parameters such as spraying distance, spraying angle, particle velocity, and temperature will affect the coating quality. For example, in high-velocity oxygen fuel (HVOF) or plasma spraying, higher particle velocity and appropriate temperature are helpful for the particles to melt better and impact the substrate surface, forming a dense and tightly bonded coating structure.

　　Moreover, selecting the appropriate spraying material is also one of the key factors for improving adhesion. Different materials have different thermal expansion coefficients and wettability. Choosing a spraying material with a thermal expansion coefficient similar to that of the substrate can reduce thermal stress and prevent the coating from cracking or peeling off during the cooling process. In addition, introducing an intermediate layer or bonding layer, such as NiCr, CoCr, etc., during the spraying process also helps to improve the interface bonding strength between the coating and the substrate.



Finally, the heat treatment process after spraying can also effectively improve the adhesion of the coating. Through appropriate heat treatment (such as annealing), the internal residual stress of the coating can be reduced, promoting the diffusion bonding between the coating and the substrate, further enhancing the adhesion and overall performance of the coating.



In summary, improving the adhesion of thermal spraying coatings is a systematic project, involving multiple links such as substrate pretreatment, optimization of spraying parameters, material selection, and post-treatment. Only by doing scientific and reasonable work at each link can the advantages of thermal spraying technology be fully utilized, obtaining functional coatings with excellent performance and strong adhesion that meet the high standards of material performance in different industrial fields.