The Effect of Detonation Frequency on the Linear Reciprocating Wear Behavior of Detonation Sprayed Ni-20%Cr Coatings at Elevated Temperatures

The study explores the impact of detonation frequency (3 and 6 Hz) on the temperature-dependent linear reciprocating wear behavior of Ni-20%Cr coatings deposited by detonation spraying on a nickel-based superalloy (IN718). Dry sliding experiments were carried out at both ambient (25 °C) and high (420 °C) temperatures, using an alumina (Al₂O₃) ball as the counter material and different loads (5, 10, and 20 N). HV_0.2 microhardness indentations were used to test material hardness variations attributed to heat exposure. X-ray diffraction (XRD), Raman spectroscopy, and field emission scanning electron microscopy with energy-dispersive spectroscopy (FESEM with EDS) were used to investigate the wear characteristics and mechanisms. Furthermore, surface roughness and profiles of worn surfaces (including track depth, breadth, and wear volume) enabled the calculation of wear rates using confocal optical 3D profilometry. The results showed the 6 Hz Ni-20%Cr coating showed better wear resistance than the 3 Hz coating. However, a higher wear rate and low friction coefficient at 420 °C were observed due to partial oxide particles, which were insufficient to restrict direct ball-to-metal contact. The research delves into wear maps, tribolayer formation, wear mechanisms, and sub-mechanisms.