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Effect of Organic Inhibitor on Corrosion of Mild Steel in Hydrochloric Acid
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Abstract
The inhibition effect of thiourea, hexamethylenetecramine
and N-N I -dicyclohexylthiourea on mild steel
corrosion in hydrochloric acid solutions has been examined by
means of a hydrogen-evolution measurement and
the surface observation of corroded specimens. The evoiltion
-rate of hydrogen by the steel was kept constant in
the acid solution with thiourea. In contrast, the evo-
1ution-rate redueced with time in the acid solution with
the other inhibitors. The inhibitor concentration at
which the inhibitor efficiency was over 90% was 500ppm
for thiourea and only 50ppm for the other inhibitors.
The surface of corroded specimens was much smoother in the
acid solution with hexamethylenetetramine than in the acid
solution with thiourea, regardless of the corrosion-rate.
Thus, hexamethylenetetramine has been found as an excellent
inhibitor for the corrosion of mild steel in hydrochloric
acid solution