工艺参数对冷喷涂WC-17Co/Ni 复合涂层性能影响

Aluminum alloys are widely used in aerospace applications such as aircraft structures, engine components, and cabin walls owing to their excellent specific strength, superior machinability, and light weight. However, they still face certain challenges, including wear resistance, corrosion resistance, and durability, in practical applications. To enhance the properties of aluminum alloys, WC-17Co hard-alloy coatings have been applied for surface protection. Cold spraying, as an advanced solid-phase deposition technology, has the advantage of significantly reducing the working temperature compared with traditional thermal spraying. This low temperature enables cold spraying to effectively avoid metal oxidation and harmful interfaces at high temperatures, ensuring that the microstructure and properties of the spraying material are not degraded, extending the service life, and improving the material’s durability. Accordingly, WC-17Co/Ni composite coatings with a volume fraction of 80vol.% WC-17Co were prepared on AA2024 substrate via cold spraying. The microstructure, mechanical properties, and bending properties of the AA2024 substrate were analyzed via optical microscopy, scanning electron microscopy, microhardness testing, and a universal material testing machine. The effects of gas pressure, gas temperature, and standoff distance on the deposition efficiency, microstructure, mechanical properties, and bending properties of the cold-sprayed 80vol.% WC-17Co/Ni composite coating were investigated via a three-factor, three-level orthogonal test design. The results showed that gas pressure had the greatest effect on the coating thickness, hard-phase content, and porosity, followed by gas temperature; the standoff distance had no significant effect. Higher gas pressures and temperatures can increase the particle velocity and improve the coating deposition quality. When the spraying process parameters are high (4, 5 MPa; 650, 750 ℃), the 80vol.% WC-17Co/Ni composite coating exhibits a relatively dense structure (the porosity decreases to ~1%) and high deposition efficiency (the coating thickness exceeds 300 μm), and the WC-17Co volume fraction in the coating exceeds 60vol.%. Additionally, the composite coating exhibited excellent mechanical properties. The bonding strength was slightly affected by the spraying parameters; all coatings exhibited good bonding ability (the bonding strength exceeded 30 MPa), and the coating microhardness was the most sensitive to gas pressure changes. Higher gas pressures enhanced the work-hardening effect of the composite coating by increasing the particle velocity and effectively increasing its microhardness. When the gas pressure reached 5 MPa, the average coating microhardness exceeded 400 HV_0.3. Furthermore, to further evaluate the influence of changes in the cold-spraying process parameters on composite coating durability, the WC-17Co/Ni composite coatings were tested at 90° three-point bending. The bending performance of the cold-sprayed 80vol.% WC-Co/Ni composite coating under different process parameters did not differed significantly. Although cracks appeared in the bent part of the coating, no spalling phenomenon was observed in the coating, which was caused by the WC-Co and Ni particles deeply embedded in the substrate. The WC-Co/Ni composite coating exhibits good adhesion to the AA2024 substrate. Based on experimental results, the optimal process parameters were identified as follows: gas pressure: 5 MPa; gas temperature: 750 ℃; and standoff distance: 20 mm, ensuring high-performance 80vol.% WC-17Co/Ni composite coatings. These findings provide crucial experimental data and a theoretical framework for designing superior surface coatings tailored to aerospace aluminum alloys. Overall, this study provides valuable insights into the influence of cold-spraying process parameters on the microstructure and properties of WC-17Co/Ni composite coatings. This highlights the efficacy of cold spraying in enhancing the surface protection of aerospace aluminum alloy components and promising advancements in materials engineering and application practices within the aerospace industry.