Study on growth factors of intermetallic layer within hot-dipped 25 % Al-Zn alloy coating on steel

Abstract

25% Al-Zn alloy coating performs better than hot dip galvanized coating and 55% Al-Zn-Si coating with regard to general seawater corrosion protection. This study deals with the interfacial intermetallic layer's growth, which affects considerably the corrosion resistance and mechanical properties of 25% Al-Zn alloy coatings, by means of three-factor quadratic regressive orthogonal experiments. The regression equation shows that the intermetallic layer thickness decreases rapidly with increasing content of Si added to the Zn-Al alloy bath, increases with rise in bath temperature and prolonging dip time. The most effective factor that determined the thickness of intermetallic layer was the amount of Si added to Zn-Al alloy bath, while the effect of bath temperature and dip time on the thickness of intermetallic layer were not very obvious.