Wetting assessment using the dispensed drop method in the field of hot-dip galvanizing

Marie-Laurence Giorgi (1) , Alexey Koltsov (2)

1 LGPM - Laboratoire de Génie des Procédés et Matériaux - EA 4038
2 ArcelorMittal Maizières Research SA

In hot-dip galvanizing, the steel strip is annealed in an atmosphere of N2 and H2, containing only traces of water. One of the main purposes of this heat treatment is to reduce the iron oxides present at the steel surface, in order to improve the wettability by liquid zinc. At the same time, the less-noble alloying elements (Mn, Si, P, Cr, Al) of the steel segregate to the surface and preferentially oxidize. The steel surface is then composed of metallic iron (wetted by liquid zinc) and oxide particles or films (non-wetted by liquid zinc). The main features of wetting are first presented (surface energy, triple line, contact angle) together with simple models to estimate the equilibrium contact angle (Young's, Wenzel's and Cassie's models). Two examples of studies performed by means of the dispensed drop technique in the field of hot-dip galvanizing will then be presented: the forced wetting of a partly oxidized steel by liquid Zn-Al and the final contact angle of a liquid Zn-Al droplet on iron / silica heterogeneous surfaces. Keyword: Selective oxidation, heterogeneous wetting, kinetic and surface energies

Domaines: Matériaux

Marie-Laurence Giorgi, Alexey Koltsov. Wetting assessment using the dispensed drop method in the field of hot-dip galvanizing. Galvatech 2017, Nov 2017, Tokyo, Japan. ⟨hal-01810788⟩