Akademik Veri Yönetim Sistemi
JOM, 2025 (SCI-Expanded, Scopus)
This study investigates the effect of electroless Ni-B coatings and subsequent heat treatments on the corrosion behavior of spring steels used in high-speed railway systems. Ni-B coatings were deposited via a commercial electroless plating bath, followed by heat treatment at 250 degrees C and 400 degrees C for 1 h. Surface morphology, elemental composition, and phase structure were characterized using SEM, EDS, and XRD analyses. Vickers microhardness measurements and pin-on-disk wear tests were conducted to evaluate the mechanical performance of the coatings. Corrosion resistance was evaluated by a 720-h salt spray test in accordance with EN ISO 9227. The results revealed that heat-treated Ni-B coatings exhibited improved mechanical properties, including a notable increase in surface hardness from 324 HV (uncoated) to 948 HV (400 degrees C heat-treated), and substantial reduction in wear loss. Ni-B coatings markedly enhanced corrosion resistance versus uncoated steel; however, post-deposition heat treatment reduced this benefit (HT-250 > HT-400 in corrosion). Crystalline Ni-borides and surface NiO formed upon annealing increase hardness and wear resistance, but introduced grain boundary-assisted corrosion pathways, lowering corrosion resistance. Corrosion performance was reported via time-to-full-rust and mass-loss-based corrosion rates. Time-to-full-rust improved from 1 h (uncoated) to 720 h (Ni-B), 240 h (HT-250), and 24 h (HT-400); corresponding corrosion rates decreased by similar to 6.6 x, similar to 3.1 x, and similar to 1.8 x.