The Al/hBN abradable seal coating is mainly used on the wall of the stator casing of the medium and low pressure compressor of aero-engine. Previous studies have found that the addition of dendritic Cu to Al/hBN powder reduces the hBN burn-off ratio in the as-deposited coating, the distribution of non-metallic components is more uniform, and the abradability of the coating is higher. This paper aims to further analyze the effect of powder hBN content on the wear performance of CuAl/hBN wear-resistant seal coating at 450 ℃ based on this research. The adopted methods include: using atmospheric plasma spraying process to prepare CuAl/hBN coatings with hBN content of 10%, 15%, 20% and 25%, respectively. The Rockwell hardness of the spray coating surface is characterized by the QUALITEST Surface Rockwell hardness tester. Using the high temperature friction and wear testing machine produced by Bruker, and setting a constant axial load, the wear morphology and mass wear ratio of the coating and the friction pair under the condition of low linear speed and 450 ℃ were studied and analyzed. Theoretical mechanism of coating wear behavior. The research results show that as the hBN content in the original powder increases from 10% to 25%, the surface Rockwell hardness of the as-sprayed coatings decreases gradually, which are 69HR15Y, 56HR15Y, 46HR15Y, and 36HR15Y, respectively. The mass wear ratios between the coating and the friction pair are -0.88%, -0.25%, -0.13%, and -1.40%, respectively. When the hBN content in the original powder is 20%, the mass wear ratio is closer to 0, indicating that in the hBN Under the content parameter, the coating wear performance is better, the quality change of the corresponding friction pair is more controllable, and the protection effect on the friction pair is better. During the relative friction between the coating and the friction pair, the wear and spalling of the coating is the main factor. The mixed transfer layer was also observed on the contact surface of the friction pin, and with the increase of the hBN content of the coating, the quality of the transfer layer on the contact surface first decreased and then increased, the surface coating degree was smoother, and the morphology fluctuation was more uniform. The increase of hBN is beneficial to improve the microstructure of the coating and improve the overall wear performance of the coating, but this is not the case in the actual IQR data statistics. The reason for this phenomenon may be that under the condition of low linear velocity, the thermal effect of friction has a high influence on the morphology of the coating and the friction pair and the wear behavior between them. Studies have shown that the thermal diffusivity of the material affects the overall frictional thermal effect between the coating and the friction pair. The increase of hBN content, on the one hand, increases the proportion of non-metallic components in the as-sprayed coating, and reduces the overall hardness of the coating. At low line speeds, the coating hardness is proportional to the thermal diffusivity. Therefore, the CuAl/hBN coating with high hBN content tends to have a lower thermal diffusivity, and the heat distribution of the friction pair is more in the wear test. Under the condition of material softening, the wear degree of the friction pair is increased. On the other hand, the thermal conductivity of hBN relative to the metal component is poor, and because hBN is mostly distributed on the boundary of the metal phase, the transfer of frictional heat is easily hindered at the boundary between hBN and the metal component, resulting in local overheating and aggravating the wear of the coating. Good wear level. Therefore, for the seal coating as a whole, the hBN component has an optimal value in theory, which ensures that the seal coating obtains the best wear performance. In general, the CuAl/20%hBN coating has better friction compatibility with the friction pair. © 2023 Chongqing Wujiu Periodicals Press. All rights reserved.
