DSC study of the deposition reactions of zinc pack coatings up to 550°C
- 82 Downloads
Zn pack coating formation takes place in three steps as differential scanning calorimetry shows. The initial step (at 193.9°C) is endothermic and involves the transformation of α-NH4Cl to β-NH4Cl and the NH4Cl decomposition to NH3 and HCl. During the second step (at 248.6°C), which is exothermic, Zn2+ salts are formed and most probably ZnCl2. Finally at 264.1°C (endothermic reaction) it seems that ZnCl2 is decomposed to form Zn that is deposited on the ferrous substrate. The as-cast Zn diffuses in the iron substrate forming the gamma and delta phase of the Fe–Zn phase diagram. Al2O3 is not involved in the above-mentioned mechanism and acts only as filler.
Keywordschemical vapor deposition DSC characterization metallic coatings pack cementation
Unable to display preview. Download preview PDF.
- 2.J. W. Cambel in ‘Hot-dip coatings’, Vol. Corrosion, ASM, 2000, pp. 436–445.Google Scholar
- 3.Galvanizers Association et al. 2000The engineers and architects’ guide to hot dip galvanizingGalvanizers AssociationSutton ColdfieldGoogle Scholar
- 4.Maass, P, Peissker, P, et al. 1993Handbuch FeuerverzinkenWiley-VCHWeinheim Google Scholar
- Cr5.G. W. Goward and L. L. Seigle, in ASM Handbook, Vol. Surface Treatments, ASM, 1999, pp. 611–617.Google Scholar
- 6.He, Y, Li, D, Wang, D, Zhang, Z, Qi, H, Gao, W 2002Mater. Lett.56554Google Scholar
- 10.Alexeev, V, et al. 1975Analyse QualitativeEditions MIRMoscouGoogle Scholar