| The volatile corrosion inhibitors were made from dozens of natural plants by the ultrasonic assisted ethanol extraction method in this paper and its corrosion inhibition efficiency was measured. The Nyquist results showed that two kinds of plant-type volatile corrosion inhibitor which were extracted from garlic and myrcia had great corrosion inhibition efficiency on copper under 100?l 1mol/L NaCl and 1mol/L NaCl(pH=3.5) thin electrolyte layer at 30°C, respectively. And their inhibition efficiency are 84.1%? 72.2% under the condition of preparing membrane.The corrosion inhibition efficiency and corrosion inhibition mechanism were investigated by the electrochemical measurements, weight loss and modern instrument analytical technique. Headspace gas chromatography-mass spectrometry method(HS-GCMS) was applied to identify the volatiles of plant extracts and find out the inhibition active ingredients. The influences of pre-filmed time, temperature and the concentration of NaCl on the corrosion inhibition efficiency were investigated by electrochemical measurement technique. The corrosion inhibition efficiency of diallyl trisulfide(DATS) which is major volatile component of garlic extracts was studied on copper under thin electrolyte layer. The synergistic effect of garlic extracts and industrial corrosion inhibitor benzotriazole(BTA) was also investigated. The static weight loss was applied to evaluate the corrosion inhibition efficiency of plant-type volatile corrosion inhibitor. At the same time, the corrosion reaction activation energy is also calculated by the Arrhenius equation. The inhibition active compositions of plant extracts were further verified by the modern surface analysis technique(FSEM?ATR-FTIR?Raman?XPS). The results showed that sulfur compounds from garlic extracts and volatile compounds(Eudesmol, Terpinyl Acetate) from myrcia extracts can adsorb well on the surface of copper to form compact protective film. |
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