Zn-Fe and Y-modified Zn-Fe coatings on 42CrMo steel via pack cementation

摘要

Zn-Fe and Y-modified Zn-Fe coatings were prepared on 42 CrMo steel through pack cementation processes at 370,390 and 410℃ for 4 h.Y modification was achieved through the co-deposition of Zn and Y_(2)O_(3).The effects of Y modification on microstructure,formation and corrosion behavior of the Zn-Fe coating were investigated.The coating thickness increased with an increase in temperature.The Y-modified Zn-Fe coating was thicker than the plain Zn-Fe coating.Both the Zn-Fe coating and Y-modified Zn-Fe coating showed single-layered structures,but the overall microstructure was improved by Y modification.The activation energies for Zn-Fe coating and Y-modified Zn-Fe coating were 113.15 and80.65 kJ·mol^(-1),respectively.The Zn-Fe coating consisted of FeZn_(13) and Fe11Zn40 phases.The effects of Y modification on the corrosion behavior of the Zn-Fe coating were evaluated through an immersion test and polarization measurements.The results showed that the corrosion resistance was improved by Y modification.