Zinc deposition with pack cementation on low carbon steel substrates

The structure of Zn coatings formed with pack cementation at 250, 350, 380, 400 and 450 °C have been studied with Scanning Electron Microscopy, X-ray diffraction and microhardness measurments. From this investigation it turned up that these coatings are composed of two layers referring to Γ-Fe11Zn40 and δ-FeZn10 phases of the Fe–Zn phase diagram, while inclusions were also detected, composed of Fe and Zn at almost equal concentrations. Furthermore it was deduced that the coating thickness at 400 and 450 °C is a function of t1/2, where t is the heating time. However, the microstructure is similar in every case. Finally, it was concluded that the microhardness of the pack coatings is higher than the microhardness of the hot-dip galvanized coatings.