Prestressing steel strands are vulnerable to chloride-assisted corrosion fatigue because localized pits can concentrate cyclic stress before appreciable section loss occurs. This study compared eight surface states, from bare steel to silane/polydopamine (PDA) bilayers grown for 3-24 h, using surface characterization, electrochemical testing, humid chloride aging, and corrosion-fatigue testing. Silane/PDA-12h provided the best overall response, with a thickness of 176.6 f 15.1 nm, scratch critical load of 6.86 f 0.88 N, initial |Z|0.01 Hz of 9.11 x 105 Omega cm2, and corrosion current density of 0.194 f 0.069 & micro;A cm-2. After 56 humid chloride cycles, its maximum pit depth was 17.0 f 3.7 & micro;m versus 108.8 f 16.9 & micro;m for bare steel; at a 500 MPa stress range, mean fatigue life increased from 0.35 x 106 to 1.44 x 106 cycles. The 24 h film was thicker but less durable, showing that barrier continuity, resistance to electrolyte uptake, and adhesion are more important than maximum thickness.
[1]Kunming Met Coll, Fac Environm & Chem Engn, Kunming 650033, Yunnan, Peoples R China.
[2]Kunming Met Coll, Fac Architecture Engn, Kunming 650033, Yunnan, Peoples R China.
[3]Kunming Met Coll, Logist & Infrastructure Management Ctr, Kunming 650033, Yunnan, Peoples R China.
(8.0+极速模式)