Tribological Behavior of Binder-Jetted STS316L Sintered Bodies and Cu-Infiltrated Composites

Binder-jetted metallic components retain residual porosity after sintering, which can substantially affect their mechanical and tribological performance. This study clarifies how sintering-induced pore evolution and Cu infiltration influence the wear mechanisms of binder-jetted STS316L. STS316L specimens were sintered at 1100, 1200, and 1300 °C, and corresponding Cu/STS316L composites were fabricated by molten Cu infiltration. Their microstructures and wear behavior were analyzed using Filed-emission scanning electron microscopy (FE-SEM), Energy-dispersive X-ray spectroscopy (EDS), Confocal laser scanning microscopy (CLSM), X-ray diffraction (XRD), and cross-sectional Transmission electron microscopy (TEM). As the sintering temperature increased, the relative density and hardness of the sintered specimens increased from 72.75% to 80.69% and from 194 to 243.8 HV, respectively. Nevertheless, their average coefficient of friction increased from approximately 0.25 to 0.71, while the wear width and maximum depth increased from 932.8 to 1492.0 μm and from 24.7 to 60.3 μm, respectively. Abrasive and adhesive wear predominated at 1100 and 1200 °C, whereas repeated formation, cracking, and delamination of an approximately 2.5 μm thick oxygen-rich tribolayer caused severe oxidative delamination at 1300 °C. Cu infiltration increased the relative density to 90.68–95.69%. The composites exhibited similar friction behavior, with an average coefficient of friction of approximately 0.6, and were governed primarily by adhesive wear associated with Cu transfer and plastic deformation. These results demonstrate that increased densification does not necessarily improve wear resistance and that pore structure and Cu transfer critically determine the dominant wear mechanisms.