科研之友
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摘要
The anti-tamish film was formed on brass for coinage by 1-phenyl-5-mercaptotetrazole (PMTA), which was studied by accelerated corrosion test (metallic coatings-thioacetamide corrosion test), polarization curves and electrochemical impedance spectroscopy (EIS) in synthetic sweat solution. The accelerated corrosion test showed that PMTA exhibited better anti-tarnish performance on brass than that of traditional anti-tarnish agent benzotriazole (BTA). The polarization measurements showed that PMTA could be classified as a mixed inhibitor for it could restrain both anodic and cathodic reactions. EIS measurements indicated that the inhibition efficiency of PMTA on brass was over 98.4% in synthetic sweat solution. All these results showed that PMTA was an excellent anti-tamish agent of the brass for coinage, the optimum treating conditions of which were 0.5 gL(-1), pH = 3, 55 degrees C-85 degrees C, 7 min.
