04 May 2020
Research Paper

Tailoring vapor-deposited ZnMg-Zn bilayer coating for steels by diffusion-driven phase transformation

S. Sabooni, E. Galinmoghaddam, L.Q. Lu, Y.T. Pei; University of Groningen, The Netherlands
A.A. Turkin; National Science Center “Kharkiv Institute of Physics and Technology”, Kharkiv, Ukraine
R.J. Westerwaal, C. Boelsma, E. Zoestbergen; Tata Steel, IJmuiden, The Netherlands

This study reports a “high temperature fast annealing” approach to tailor the microstructure of ZnMgeZn bilayer coatings through a diffusion-driven phase transformation and to improve the adhesion strength and corrosion resistance, simultaneously. Selection of the appropriate annealing condition, 250 C for 3 min, promotes the formation of MgZn2 on the topmost surface of the coating and Mg2Zn11 at the interface of ZnMg/Zn. This results to an increase of the adhesion strength from 65 MPa in the asdeposited condition to 82 MPa after annealing as well as a reduction in the corrosion current density from 0.91 to 0.52 mA/cm2, indicating enhanced corrosion resistance. The diffusion of the elements at high temperatures is also modeled to predict the stability region of phases during the annealing treatment. An excellent correlation is obtained between simulation and the experimental results.

Article published in 'Journal of Alloys and Compounds' 836(2020) 155448, available online 4 May 2020

DOI available