Oxidation Behavior of NiCoCrAlY Coatings Deposited by Vacuum Plasma Spraying and High-Velocity Oxygen Fuel Processes

To reduce the formation of detrimental complex oxides, bond coatings in thermal barrier for gas turbines are typically fabricated using vacuum plasma spraying (VPS) or high-velocity oxygen fuel (HVOF) process. Herein, VPS and HVOF processes were applied NiCoCrAlY + HfSi-based powder to assess oxidation behavior both coating processes. Each coated sample was subjected 50 cyclic heat treatments at 950 °C 23 h cooling 1 20 with nitrogen gas, weight change during treatment measured evaluate behavior. After test, layer analyzed X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS). The exhibited faster gain than because alumina particles generated initial inhibited diffusion. formed a dense thick growth oxide (TGO) until middle test remained stable end evaluation. However, demonstrated rapid loss final cycles. Alumina within coat suppressed diffusion internal elements prevented Al from being supplied surface. isolation accelerated spinel TGO due Ni, Co, Cr near as-coated showed higher hardness lower interfacial bonding strength did. Diffusion induced by after furnace (FCT) led similar strengths layers. improve quality process, densification layer, suppression formation, uniform on surface must be additionally implemented.