硫酸浴からのZn-Co合金めっきの腐食挙動 [in Japanese] Corrosion Behavior of Electroplated Zn-Co Alloys from Sulfate Solutions [in Japanese]
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We studied corrosion by Zn-Co alloys electroplated from sulfate solutions onto iron substrate in a salt spray test (SST) by using scanning electron, X-ray diffraction, and X-ray photoelectron spectroscopy (XPS).<br>We found Zn-Co alloy surfaces corroded by SST to be covered by corrosion products (white rust) consisting of Zn(OH)<sub>2</sub>, ZnO, Zn<sub>5</sub>(CO<sub>3</sub>)<sub>2</sub>(OH)<sub>6</sub>, and ZnCl<sub>2</sub>·4Zn(OH)<sub>2</sub> due to the dissolution of Zn. For γ-phase alloys consisting of 10∼20wt%Co, a corrosion product with low electrical conductivity (ZnCl<sub>2</sub>·4Zn(OH)<sub>2</sub>) formed mainly with the corrosion product apparently effective subsequently as a barrier against further corrosion. The good corrosion resistance of γ-phase films can be attributed to conversion to a more noble-metal site due to Co concentrating on the corroded surface as corrosion advanced.
- Jitsumu Hyomen Gijutsu
Jitsumu Hyomen Gijutsu 47(6), 524-528, 1996-06
The Surface Finishing Society of Japan