Microstructural, Mechanical, and Tribological Evaluation of Cu-Al-based Coatings Deposited by APS and HVOF

Thermal-sprayed coatings have been extensively used in aerospace with the main purpose to overcome critical challenges such as abrasive wear, corrosion, and erosion under high temperatures and pressures. Cu-Al-based thermal sprayed coatings are commonly employed in tribological interfaces within gas turbine engines to improve the wear resistance. These coatings are typically deposited by more traditional thermal spray techniques such as Air Plasma Spray (APS), which can result in high amounts of oxidation within the coating. The main purpose of this study is to carefully analyze and assess a lower temperature deposition technique that is High Velocity Oxygen Fuel (HVOF). More specifically, commercially available Cu-10Al powders were deposited by APS and HVOF and compared in terms of their microstructural, mechanical properties, and tribological behavior at various temperatures. The results showed that the friction coefficient for both coatings was equivalent at room temperature while it was lower for the APS coating at high temperature when compared to the HVOF one. Similarly, the specific wear rates showed little difference between the different deposition processes at room temperature while the APS coating had a lower wear rate at elevated temperature when compared to the HVOF coating. The differences in the friction and wear behavior were attributed to differences in the interactions and phenomena that occur at the interface between the coating and counter balls.