Influence of calcium on the morphology and corrosion performance of hot-dip Al-Si coatings

Hot-dip aluminizing coatings are gaining attention owing to their corrosion resistance under harsh conditions and economic viability. Although Ca incorporation into metal alloy coatings has been demonstrated to improve the corrosion resistance, Ca addition to hot-dip aluminizing coatings is yet to be reported. Here, we investigated the effect of the Ca content on the microstructures and electrochemical properties of hot-dip aluminizing coatings on commercial quality steel. Defect-free coatings were obtained by optimizing the hot-dipping parameters. Ca promoted the precipitation of CaAl2Si2, altering the morphology of the coating and improving the corrosion resistance. However, owing to the limited stability of the passive layer, the inclusion of Ca did not significantly affect the long-term corrosion characteristics of the Al alloy coating.