Development of thermal barrier coating on single crystal superalloy CMSX-4 by two-source evaporation EB-PVD and hot corrosion performance of the coating in a simulated aero-engine environment

• Published in: Surface & coatings technology 2024-06, Vol.485, p.130885, Article 130885
• Main Authors: Vaiyapuri, Santhosh Kumar, Moganraj, Arivarasu, Nowotnik, Andrzej, Mrowka-Nowotnik, Grazyna
• Format: Article
• Language: English
• Subjects: CMSX-4; EB-PVD; Hot corrosion; Oxidation; Single crystal superalloys; TBC
• ISSN: 0257-8972; 1879-3347
• DOI: 10.1016/j.surfcoat.2024.130885

Superalloys are crucial in high-temperature applications, particularly in the gas turbine industries. With the development of high-temperature superalloy materials, efforts are still being made to improve the turbine entry temperature (TET), which will ultimately raise the efficiency of gas turbines. In this research, a second-generation single-crystal superalloy CMSX-4 based on nickel was prepared. The surface was coated by thermal barrier coating (TBC) with a bond coat of NiCoCrAlY with vacuum plasma spray (VPS) and a top coat with Yttria Stabilized Zirconia (YSZ) by Electron Beam Physical Vapor Deposition (EB-PVD) with a minimal current of 2.3 A with two sources compared to the conventional high-current that has been currently employed. These CMSX-4 specimens, both the as-cast and TBC coated, were used to test the effects of cyclic oxidation and hot corrosion at 1000 °C, simulating an aircraft engine. Also, a hot corrosion test using salt compositions (Wt%) of 60Na2SO4 - 40NaCl was performed simulating an aviation engine environmental condition. A FE-SEM/EDS analysis was used to examine the surface and cross-section microstructures of oxidized, hot-corroded as-cast, and hot-corroded TBC-coated CMSX-4 and its corrosion products. Using the XRD technique, the phases that were found in the oxidized and hot-corroded samples were identified. The outcome demonstrated that the EB-PVD TBC-coating on CMSX-4 with beam switching technique and a lower electron beam current has adequate protection without any damage to the coatings at 1000 °C. •EBPVD processes with a beam-switching with continuous evaporation of two targets•Beam switching increased the coating window increasing productivity.•Successful coating with a 23 % lower electron beam current, was achieved.•Optimized scanning trajectory increased the aggressiveness of the electron beam.