Evaluation of microstructure and mechanical properties of thermally sprayed NiCrAlY bond coats on Superni C-263 aero engine combustor liner alloy

Abstract

• Comparative analysis of APS and HVOF thermal spray processes reveals superior microstructural and mechanical performance of HVOF-sprayed NiCrAlY bond coats. • HVOF coatings exhibit 40 % higher tensile bond strength (54 MPa vs. 34 MPa) and significantly lower porosity (1.56 Vol. % vs. 5.63 %) than APS coatings. • Enhanced hardness (486 HV vs. 420 HV) and reduced surface roughness (Ra = 3.5 μm vs. 5.2 μm) in HVOF coatings contribute to improved durability and wear resistance. • First-time evaluation of NiCrAlY coatings on Superni C-263 alloy highlights their potential as advanced thermal barrier coatings for aero-engine components. • Findings establish HVOF as a superior deposition technique for next-generation bond coats, ensuring improved service life and performance in high-temperature aerospace applications. Thermal spray coatings are widely used for protecting aero engine hot section components. The present investigation aimed at assessing the microstructural and mechanical properties of thermally sprayed NiCrAlY bond coats deposited over the nickel based super alloy Superni C-263 combustor liner alloy used in aero engines. To understand the microstructural and mechanical characteristics, Atmospheric Plasma Spray (APS) and High velocity oxy fuel (HVOF) spray NiCrAlY bond coatings were compared. The micro and mechanical results showed that HVOF sprayed coatings have dense microstructure, higher microhardness, and improved tensile bond strength as compared to APS process. The HVOF sprayed NiCrAlY bond coats show lesser porosity values (1.56 Vol. % vs. 5.4 Vol. %), higher microhardness (486 HV vs. 422 HV), and low surface roughness (Ra = 9.2 μm compared to Ra = 10.6 μm). Further, tensile bond strength of coatings deposited using the HVOF process was 40 % higher than APS (54 MPa vs. 34 MPa). The results indicate that HVOF-sprayed NiCrAlY bond coats have strong potential to develop thermal barrier coatings for aero engine components made by Superni C-263 combustor liner alloy