Influence of the Spray Angle, Standoff Distance, and Traverse Speed of the Spray Gun on the Tribomechanical Properties of Cold-Sprayed Inconel 718 Coatings

Abstract Superalloys such as Inconel 718 are the preferred materials for highly stressed components in turbine jets as they offer a combination of high strength and excellent resistance to oxidation and corrosion. Despite their exceptional properties, these materials are subject to intense wear, thermal cycling and high-temperature oxidation during operation, which results in high costs and poses risks to safety-critical components. Cold gas spraying presents a promising and very flexible method for coating and repairing such components. However, there are still significant gaps in our understanding of how process guidance influences coating formation and the resulting properties. In this study, the influence of different handling parameters of the robotic motion system (specifically the spray angle, standoff distance, and traverse speed) on the mechanical coating properties (microhardness, porosity, and roughness), the tensile strength, the microstructure formation, and the tribological performance during high-pressure cold gas spraying of Inconel 718, utilizing nitrogen as the process gas, was investigated. It has been found that the spray angle is the most critical factor influencing the deposition rate, the microstructure / porosity, the tensile strength, and the roughness of the coatings, whereas the microhardness remained unaffected. At the lowest spray angle of 90°, significant coating defects and lowest deposition rate were observed. Coatings applied with varying spray angles were also examined for their sliding wear and friction properties. The primary wear mechanism identified was abrasion, characterized by the presence of aluminum oxide debris within the wear track. No significant influence of the spray angle on the wear behavior of the coatings was observed.