1963 年 12 巻 5 号 p. 226-228
Studies were carried out on the anodic behaviours of stainless steels in HNO3 containing halogen ions.
The results obtained were as follows:
(1) In HNO3 solution containing halogen ions, the critical current density in active state was larger than in H2SO4 solution.
(2) Of the halogen ions added to HNO3 solution, the one that had the strongest action in preventing the passivation of metallic Ni was found to be Br- ion, while for Fe, Fe-Cr, Fe-Ni and Fe-Cr-Ni alloys it was Cl- ion.
(3) The oxidation action of HNO3 made Ni and Fe-Ni alloys depolarize, and, thereby, the anodic dissolution of Ni and Fe-Ni was made much easier than that in H2SO4 solution. But Fe-Cr alloys which become passive easily were found to become passive as soon as they are set as alloy anodes.
While in the passive state, the oxidation action of HNO3 had the two effects: one makes the passive film steady and the other inhibits the indirect dissolution reaction as Cr6+→Cr3++3e-by Cl- ion.