Oxide film thickening on the surface of iron-chromium alloys in relation to anion type and concentration
✍ Scribed by J.M. Abd El Kader; F.M. Abd El Wahab; M.G.A. Khedr; A.M. Shams El Din
- Publisher
- Elsevier Science
- Year
- 1982
- Weight
- 607 KB
- Volume
- 7
- Category
- Article
- ISSN
- 0390-6035
No coin nor oath required. For personal study only.
✦ Synopsis
The variation with time of the open Cll'CUlt potentials of four Fe-Cr alloys of increasing Cr content is followed m strongly aerated solutions of CI', Br', I-, NO~, SO~-, WO4-, CrO~-, and H2PO 4 of varying molaritles, till the attainment of steady state values Difference m behavlour is noted between Alloy I (7*/, Cr) and the other three Alloys (/> 13'/, Cr) With Alloy I, film thickening is noted only m very dilute salt solutions, whilst film destruction and dissolution operates m more concentrated media With the three other alloys film formation describes the behavlour Film thickening m all solutions follows a dtrect logarithmic law, with rates depending on the nature of amon m solution, and alloy composition The action of the various amons is spectflc In solution of the same amon the thickness of the oxide film increases with the Cr content of the alloy Phosphate solutions produce sxgnlflcantly thicker passlvatmg fdms
The behavlour of the Fe-Cr alloys m CrO]" solutions is unexpected Wlulst pass~vatlon xs expected, the changes m potential denote fdm destruction
The steady-state potentials measured m solutions of equtrnolar concentrations of the various anxons are not the same These potentials tend towards more negative values with the increase of anion-content of the solution Under other-w~se the same conditions, the steady-state potentials tend towards nobler values with the increase of the Cr-content of the alloys