Application of secondary ion mass spectrometry with flight of time analyzer (TOF-SIMS) to study the corrosion resistance of conversion layers produced by reaction of chromium(III) on zinc coatings on carbon steel

摘要

Samples of C steel coated with a 8 pm thick layer of Zn were treated with HNO3 soln. and then passivated in com. Cr(III) salt solns. to produce conversion layers. Corrosion resistance of the layers was detd. on basis of polarization curves, impedance measurements and salt chamber tests. The chem. compn. of the layers was analyzed by using TOF-SIMS. The Cr compds. reacting with Zn during passivation resulted in formation of mixed ZnCrxOy, oxides. Furthermore, the corrosion rate detd. by elecirochem. methods and saline chamber test depended on the content of F ions in the passive layer.