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A Study on the Impact of Extract of Green Coffee Beans as a Green Corrosion Inhibitor of Mild Steel in Simulated Concrete Pore Solution

Khalili Azar, Mojtaba | 2020

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 53396 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Afshar, Abdollah
  7. Abstract:
  8. In this study, the effect of green coffee extract powder, as a green corrosion inhibitor of steel in a concrete simulation environment was investigated. In this study, the green coffee extract was obtained by the Maceration method and its performance was investigated by weight loss method, electrochemical methods including Polarization, Electrochemical Impedance Spectroscopy. Scanning Electron Microscopy images were also used to visualize the corroded areas. The results of the polarization test showed that 450 mg/lit of coffee extract powder at 25 °C has the corrosion inhibiting efficiency of about 82% and the corrosion rate of the bare sample reduced from 6 to 1.16 mpy. The dosage of 550 mg/lit at 40 °C improved the corrosion inhibition efficiency to about 96% and decreased the corrosion rate of the sample from 13 mpy to 0.57 mpy. With the increase of temperature, more concentrations of inhibitors are needed. Thus, 650 mg/lit of the green inhibitor causes corrosion inhibition efficiency of about 97% at 55 °C. At this temperature, the corrosion rate in the absence of green coffee extract powder reached 19 mpy and in the presence of 650 mg/lit green inhibitor reached about 0.61 mpy. Also, the impedance spectroscopy test in concrete simulation medium and 25 °C showed that the presence of 450 mg/lit of coffee extract powder increases the charge transfer resistance from 4036, for the control sample, to 25369. Scanning Electron microscope images confirm the proper performance of green coffee extract powder. The images exhibit the sever corroded areas and corrosion products of the bare sample after 20 days of immersion at 25 °C, while with the presence of 450 mg/lit green corrosion inhibitor, the corroded regions are dramatically decreased
  9. Keywords:
  10. Natural Extract ; Green Corrosion Inhibitor ; Concrete ; Corrosion ; Simulated Concrete Pore Solution ; Green Coffee Bean Extract ; Mild Steel ; Steel Corrosion

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