Abstract
In this study, the aim was to deposit layers of the Ni22Cr10Al1Y coating using the vacuum plasma spray process to protect gas turbine engine components from oxidation and high-temperature corrosion. The coating can significantly affect the properties of the substrate because it forms a composite together with the substrate. The type of the coating deposition process and coating heat treatment, together with the substrate, significantly affect its resistance to high temperature creep. Ni22Cr10Al1Y powder was deposited with a vacuum plasma spray system of the Plasma Technik AG company using the control panel A-2000 and the plasma gun F4. The coating deposited on the substrate of INCONEL X-750 alloy was thermally treated at 1100 o C for 2 hours in a protective atmosphere of argon. The particle morphology was tested by scanning electron microscopy.The microhardness of layers was tested by the HV0.3 method and the bond strength was tensile tested, in accordance with the standard Pratt & Whitney. The microstructure of the deposited coating layers was examined under a light microscope. Coating etching was done by mixing 2.5 ml of nitric acid HNO3 with 7.5 ml of hydrofluoric acid HF. The microstructure of the etched coating before and after heat treatment, as well as the thickness of the diffusion zone, were analysed under a light microscope, based on which the coating quality was later assessed.
Highlights
The components of hot sections, such as gas turbine blades, have to withstand various stresses and severe environmental conditions at the operating temperatures of 900°C to 1000°C
MCrAlY alloys have been widely used while vacuum plasma spraying (VPS) is the leading process used for depositing coatings on hot sections such as blades which are exposed to aggressive gases at high temperatures
The lower value of the microhardness of the VPS Ni22Cr10Al1Y coating compared to the APS coating is caused by the absence of oxygen in the vacuum chamber, which prevents oxidation of molten particles in the deposition process
Summary
The components of hot sections, such as gas turbine blades, have to withstand various stresses and severe environmental conditions at the operating temperatures of 900°C to 1000°C. Examinations have shown that the microstructure of the MCrAlY coating thermally processed at 1000°C for 1 hour and cooled with argon to the room temperature for 15 min consists of a γ- solid solution rich in Ni, Co and Cr, which contains the dispersed phases of β-NiAl and γ'(Ni,Cr) (Funk, et al, 2011, pp.2233-2241), (Tang, et al, 2006, pp.106). In case of the Ni22Cr10Al1Y coating, vacuum deposited on the substrate of the 1N738LC nickel alloy, and after thermal processing in vacuum at a temperature of 1100°C for 2 hours, its microstructure shows the presence of fine globular particles of the -NiAl phase (dark gray) and uniformly distributed in the matrix of γ-Ni(Cr) + γ'-Ni3Al which is light gray (Funk, et al, 2011, pp.2233-2241). Because of the diffusion of chemical elements from the substrate, the lower layers of the coating contain the elements Ni and Ti which build fine γ'-Ni3(Al,Ti) precipitates with aluminum (Itoh, Tamura, 1999, pp.476-483), (Gómez-Acebo, et al, 2004, pp.237-251), (Dahl, et al, 2006, pp.73-78)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
