Synergistic effects between sodium tripolyphosphate and zinc sulfate in corrosion inhibition for copper in neutral tap water
- National Univ. of Singapore (Singapore)
The corrosion inhibition behavior of sodium tripolyphosphate (Na{sub 5}P{sub 3}O{sub 10}, or TPP) and zinc sulfate and the synergistic effects between them were studied for copper in neutral simulated tap water using electrochemical methods, x-ray photoelectron spectroscopy, and scanning electron microscopy. Zn{sup 2+} alone showed few inhibiting effects on copper corrosion. The film formed in the presence of Zn{sup 2+} was porous and composed mainly of cuprous oxide, which was similar in morphology and composition to films formed in the absence of the inhibitor. In the presence of TPP, a smooth and compact film, believed to be of Cu(II)-TPP compounds, formed on the copper surface. More protective films were formed in solutions containing TPP and Zn{sup 2+} as a blend. High zinc content (15% to 19%) was detected by XPS. Synergistic effects of TPP and Zn{sup 2+} were believed to result from formation of Zn(II)-TPP compounds that incorporated in the films, with Cu(II)-TPP in the upper layer and Cu{sub 2}O in the inner layer. The zinc compounds increased the anodic diffusion resistance of copper ions in the films and enhanced polarization of the cathodic reduction of dissolved oxygen.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 514784
- Journal Information:
- Corrosion, Journal Name: Corrosion Journal Issue: 7 Vol. 53; ISSN 0010-9312; ISSN CORRAK
- Country of Publication:
- United States
- Language:
- English
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