Role of Surface Morphology Evolution in the Tribological Behavior of Superalloy Under High-Temperature Fretting

High-temperature fretting wear typically occurs on mechanical contact surfaces in high-temperature environments, with displacement amplitudes generally in the micrometer range (≤300 μm), such as the turbine disks and blades in aerospace engines, and the piston rings in automotive engines. The study performed tangential fretting wear tests between superalloy specimens and Si₃N₄ balls under 700 °C to investigate the influence of ground and milled surface morphologies on the high-temperature fretting wear behavior. The experimental results show distinct wear mechanisms for the two surface types: ground specimens exhibit adhesive and oxidative wear, while milled specimens experience fatigue and abrasive wear. Both wear modes intensify with increasing load and fretting frequency. A comprehensive surface morphology characterization method, combining fractal dimension (<i>FD</i>) and surface roughness, is proposed. The study reveals that the roughness parameters <i>Sa</i> and <i>Ra</i> are strongly correlated with the Coefficient of Friction, while <i>FD</i> is strongly correlated with the wear volume. This study provides a novel approach to characterizing the evolution of surface morphology during high-temperature fretting wear.