Comparative Oxidation Performance of NiCoCrAlY Coatings Deposited by HVAF and HVOF for Thermal Barrier Applications

High Velocity Air Fuel (HVAF) and High Velocity Oxy Fuel (HVOF) are advanced thermal spray techniques developed to produce dense, oxidation-resistant coatings. These methods are particularly important for thermal barrier coating (TBC) applications in the aerospace industry. HVAF, in particular, has shown greater potential for producing dense bond coats with minimal in-flight particle oxidation, making it ideal for TBC systems. In this study, NiCoCrAlY coatings were deposited on Hastelloy-X substrates using both HVAF and HVOF techniques, and their oxidation performance was evaluated at an elevated temperature over varying durations. This approach provided insights into the oxidation mechanisms and kinetics as they evolved over time. Deposition parameters were thoroughly characterized using AccuraSpray diagnostics, while the microstructure and oxide formation were examined using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). Oxidation tests revealed that HVAF-deposited coatings have greater potential those deposited via HVOF, demonstrating superior oxidation resistance. These findings highlight the effectiveness of HVAF for producing high-performance bond coats for TBC applications, particularly in environments requiring long-term oxidation resistance.