Corrosion performance improvement of hot-dipped galvanized (HDG) steels by electro-deposition of epoxy-resin-ester modified bis-[tri-ethoxy-silyl] ethane (BTSE) coatings

A water-based epoxy-resin-ester modified bis-[tri-ethoxy-silyl] ethane (BTSE) organosilane coated by electro-deposition was tried on hot-dipped galvanized (HDG) steel for corrosion protection. Various resin ratios were tested with different electro-deposition cathodic currents. FTIR showed a more cross-linked siloxane network (SiOSi) by electro-deposition than by immersion. AFM, SEM, EDX examined the morphology and interface between the coating and substrate. Performance tests of salt spray test (SST), electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization showed the corrosion resistance of BTSE-resin film was dramatically increased by electro-deposition. A corrosion protection morphology was proposed according to the results in this work.