Protection of Zn–Ti–Cu alloy by cerium trichloride as corrosion inhibitor

Zinc alloys with additions of Ti and Cu present excellent creep resistance and an improvement in strength and hardness compared with pure Zn. However, these elements cause a decrease in localised corrosion resistance due to the presence of TiZn 15 intermetallic particles. In the present work, the corrosion behaviour of the Zn–0.084 %Ti–0.18%Cu alloy in a NaCl solution, with and without cerium salts, has been studied. Polarization curves recorded in the non-inhibited solution reveal a corrosion mechanism under cathodic control with a corrosion rate of about 1.6×10 −5 A/cm 2. Localized attack can be observed in the rolling direction after immersion in the electrolyte. A three-dimensional layer is formed on the surface when inhibitor is added to the electrolyte. This layer is due to the precipitation of insoluble cerium hydroxide on the cathodic areas, which correspond to TiZn 15 intermetallic particles. Inhibition percentages up to 98% after immersion for 4 h with 500 and 1000 ppm concentrations have been obtained.