A long time immersion experiment of mortar specimens is carried out to investigate their degradation mechanism by sulfuric acid.Water-cement ratios of mortar are ranging from 0.5 to 0.7 and the pH value of sulfuric ac...A long time immersion experiment of mortar specimens is carried out to investigate their degradation mechanism by sulfuric acid.Water-cement ratios of mortar are ranging from 0.5 to 0.7 and the pH value of sulfuric acid is 3.5 and 4.0 respectively.The pH meter is used to monitor the soak solution and the titration sulfuric acid with given concentration is added to maintain original pH value,through which the acid consumption of mortar is recorded.A theoretical reaction rate model is also proposed based on concentration boundary layer model.The results show that theoretical model fits the experimental results well and the corrosion mechanism can be modeled by a diffusion process accompanied with an irreversible chemical reaction when pH value of soak solution is no less than 3.5.展开更多
The ethanolic extract of Kleinia grandiflora leaves was characterized and tested for its potential anticorrosion properties on mild steel in 1 M H2SO4 medium using mass-loss analysis, potentiodynamic polarization meas...The ethanolic extract of Kleinia grandiflora leaves was characterized and tested for its potential anticorrosion properties on mild steel in 1 M H2SO4 medium using mass-loss analysis, potentiodynamic polarization measurements, electrochemical impedance spectroscopy, Fourier-transform infrared spectroscopy, scanning electron microscopy, UV–visible spectroscopy, and X-ray diffraction analysis. The effect of temperature on the corrosion behavior of mild steel was studied in the range of 308 to 328 K. The inhibition efficiency was observed to increase with increasing concentration of the extract. Polarization curves revealed that the Kleinia grandiflora leaf extract is a mixed inhibitor. Impedance diagrams revealed that an increase of Kleinia grandiflora leaf extract concentration increased the charge transfer resistance and decreased the double-layer capacitance. The adsorption process obeys Langmuir＇s model, with a standard free energy of adsorption（ΔGads） of-18.62 k J/mol. The obtained results indicate that the Kleinia grandiflora leaf extract can serve as an effective inhibitor for the corrosion of mild steel in a sulfuric acid medium.展开更多
基金Funded by the National Natural Science Foundation of China(No.51078175)Natural Science Foundation of Yunnan Province (No.2008E038M)Education Foundation of Yunnan Province(No. 08Y0066)
文摘A long time immersion experiment of mortar specimens is carried out to investigate their degradation mechanism by sulfuric acid.Water-cement ratios of mortar are ranging from 0.5 to 0.7 and the pH value of sulfuric acid is 3.5 and 4.0 respectively.The pH meter is used to monitor the soak solution and the titration sulfuric acid with given concentration is added to maintain original pH value,through which the acid consumption of mortar is recorded.A theoretical reaction rate model is also proposed based on concentration boundary layer model.The results show that theoretical model fits the experimental results well and the corrosion mechanism can be modeled by a diffusion process accompanied with an irreversible chemical reaction when pH value of soak solution is no less than 3.5.
文摘The ethanolic extract of Kleinia grandiflora leaves was characterized and tested for its potential anticorrosion properties on mild steel in 1 M H2SO4 medium using mass-loss analysis, potentiodynamic polarization measurements, electrochemical impedance spectroscopy, Fourier-transform infrared spectroscopy, scanning electron microscopy, UV–visible spectroscopy, and X-ray diffraction analysis. The effect of temperature on the corrosion behavior of mild steel was studied in the range of 308 to 328 K. The inhibition efficiency was observed to increase with increasing concentration of the extract. Polarization curves revealed that the Kleinia grandiflora leaf extract is a mixed inhibitor. Impedance diagrams revealed that an increase of Kleinia grandiflora leaf extract concentration increased the charge transfer resistance and decreased the double-layer capacitance. The adsorption process obeys Langmuir＇s model, with a standard free energy of adsorption（ΔGads） of-18.62 k J/mol. The obtained results indicate that the Kleinia grandiflora leaf extract can serve as an effective inhibitor for the corrosion of mild steel in a sulfuric acid medium.
