Frictional Frequency-Dependent Tribocorrosion Behaviors of Atmospheric Plasma-Sprayed FeCoCrNiMn High-Entropy Alloy Coatings in Simulated Seawater
摘要
FeCoCrNiMn high-entropy alloy coatings were deposited on 304 stainless steel substrates via atmospheric plasma spraying, and the tribocorrosion wear behaviors of these FeCoCrNiMn high-entropy alloy (HEA) coatings in 3.5 wt.% NaCl solution at various frictional frequencies were investigated. The as-sprayed coating exhibited a typical FCC structure. The hardness of the HEA coating was 221.1 HV0.2, which was 39.0% higher than the substrate. During the tribocorrosion test, both the friction coefficient and wear rate increased as the frictional frequency increased from 0.5 to 2 Hz. The self-corrosion current density increased from 1.28 × 10−7 A cm−2 at static state to 1.22 × 10−5 A cm−2 at 2 Hz, and self-corrosion potential shifted negatively from − 0.35 to − 0.45 V as the frictional frequency increased from 0.5 and 2 Hz. These behaviors were attributed to enhanced mechanical depassivation and insufficient re-passivation with increasing frequency. The main wear mechanism was dominated by fatigue wear, together with an enhanced abrasion at higher frequencies. Quantitative analysis of the corrosion–wear synergy showed that the proportion of the wear-accelerated corrosion increased from 1.6 to 6.5% due to an increased frictional frequency.