PSI - Issue 3

Vittorio Di Cocco et al. / Procedia Structural Integrity 3 (2017) 224–230 Author name / StructuralIntegrity Procedia 00 (2017) 000–000

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Fig. 3. Kinetics formation of Zn-Sn3% coatings: intermetallic phases (etching nital 2%) on the left, thicknesses on the right.

Presence of Ti strongly influences the phases formation in the coatings. Indeed, as shown in figure 4, the section is characterized by the presence of a  phase near the steel substrate and by the presence of a multiphase layer which is the main component of coating (the multiphase layer can be considered as the coatings at lower dipping time; for this dipping time  phase is not well developed).

Fig. 4. Kinetics formation of Zn-Ti0.5% coatings: intermetallic phases (etching nital 2%) on the left, thicknesses on the right.

Thickness increases more or less in linear manner up to 360s; after this dipping time thickness increase is weak. However, the absolute values of thicknesses in Zn-Ti bath are greater than thicknesses obtained by Zn-Sn bath. The maximum thickness obtained by Zn-Sn bath at 900s is about 160  m; this value of thickness can be obtained using Zn-Ti bath with less than 180s.

Fig. 5: Multiphase layer: (A) matrix, (B) lamellar phase, (C) position of compact phase, (D) compact phase.