Mechanical and Tribological Properties of High Velocity Air Fuel-Sprayed IN625 and IN718 Coatings

Abstract

This study explores the mechanical and tribological behavior of IN625 and IN718 coatings deposited on Ni-based IN718 alloy substrates using the high-velocity air fuel, HVAF technique. Microstructural analysis revealed that the IN625 coating exhibited more visible splats, weaker bonding, and a greater presence of unmelted and partially melted regions than IN718. Both IN625 and IN718 coatings retained the original constituent phases from the powder. The IN718 coating, however, demonstrated superior mechanical properties, with its hardness and adhesion strength surpassing those of IN625 by 56% and 30%, respectively. Notably, the adhesion strength was highest in a 0.5 mm thick IN718 coating, reaching 63 MPa. At room temperature, both the coatings had significant coefficient of friction (COF) values, while the wear volume loss for IN718 was reduced by 52% compared to IN625, although IN625 showed wider wear scars with more pits, deeper grooves, and peeling. IN718 formed a glaze layer, enhancing its wear resistance. These findings suggest that optimally thick IN718 HVAF coatings hold significant promise for improving performance in various repair and cladding applications.