ISSN:
1572-8838
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
,
Electrical Engineering, Measurement and Control Technology
Notes:
Abstract A study has been made on the inhibitive efficiency of some thioureas (urea, thiourea, phenylthiourea and naphthylthiourea), in the concentration range 0.0025 to 2%, in relation to dissolution of some aluminium alloys (1060, 1100, 3003 and 5052) in 20% nitric acid solution at temperatures of 25, 35 and 45° C. It was found that the structures of the thioureas affected the inhibitive efficiency but the mechanism of inhibition remained the same. The compounds exhibited maximum protection in the concentration range 0.025 to 0.03%. A gradual lowering in the efficiency of the compounds above the concentration of 0.03% has been observed. At the concentration of 1.5%, urea appears to be a corrosion accelerator and causes localized attack on the alloy surface; the other compounds still showed some degree of inhibition. The additives were most efficient towards 1060 alloy, followed by 1100, 3003 and 5052 alloys. The protecting power of all the compounds other than urea was found to improve with increase in temperature. All the compounds appeared to inhibit corrosion by adsorbing at cathodic sites. A distinctive hump (i.e. a current maximum) is observed in the steady-state potentiostatic anodic polarization curves of the alloys. This hump is found to be affected by the inhibitors. At higher concentrations, the compounds act as cathodic depolarizers, which is confirmed by measuring steady-state corrosion potentials and cathodic polarization diagrams.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00615169
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