The potential dependence of the faradaic impedance of carbon steels in 3.5% NaCl solution was measured by ac impedance technique. The polarization resistance, and also the cathodic protection efficiency obtained from ...The potential dependence of the faradaic impedance of carbon steels in 3.5% NaCl solution was measured by ac impedance technique. The polarization resistance, and also the cathodic protection efficiency obtained from weight loss, maximized at 0.70 V with respect to saturated Ag/AgCl electrode . Consequently, the potential at faradaic impedance maximum corresponds well to the optimum cathodic protection potential. The study asults showed that the ac impedance technique is a promising method for monitoring and determining the optimum cathodic protection potential.展开更多
The corrosion-protective performance of plasma-polymerized (PP) coatings on pretreated aluminum substrates has been investigated by cathodic polarization curve measurement. The surface composition and electronic prope...The corrosion-protective performance of plasma-polymerized (PP) coatings on pretreated aluminum substrates has been investigated by cathodic polarization curve measurement. The surface composition and electronic properties of the pretreated and PP film coated metal surfaces were also characterized by XPS and the temperature-programmed photoelectron emission (TPPE). A PP coating was prepared on the pretreated surfaces by plasma polymerization of a mixture of tetraethoxysilane (TEOS) monomer vapor and oxygen using a 13.56MHz radiofrequency generator. The polarization curve of PP film coated samples was measured in NaCl aqueous solution. The weight loss rate calculated from the value of the corrosion current of the curve was used to estimate the protective performance of the PP film coated samples. Argon plasma treatment of the metal surface gave much better corrosion-protective performance than pretreatments such as oxidation by heating in air and diamond scratching. The XPS analysis indicated that the silicon oxide assigned to SiO2 was formed on the PP film coated surface. The TPPE analysis revealed that the electron emission characteristics for the metal surfaces pretreated only were strongly influenced by the pretreatments, while all the PP film coated samples exhibited nearly the same electron emission trend with a much decreased intensity.展开更多
A new cathode with Ti2 Ni alloys and Ni/Mo electrocatalyst has been developed for alkaline water electrolysis. The characterization for hydrogen evolution reaction (HER)is carried out in a 30 wt% potassium hydroxide (...A new cathode with Ti2 Ni alloys and Ni/Mo electrocatalyst has been developed for alkaline water electrolysis. The characterization for hydrogen evolution reaction (HER)is carried out in a 30 wt% potassium hydroxide (KOH) solution. The cathode shows a low hydrogen overpotential(η=60 mV at 70℃ in 30 wt% KOH) and ezcellent stability under conditions of continuous electrolysis and intermittent electrolysis with power interruption .展开更多
The effects of relative humidity (RH) on a printed circuit board finished with electroless nickel immersion gold (PCB-ENIG) under an adsorbed thin electrolyte layer (ATEL) were investigated in situ via the measurement...The effects of relative humidity (RH) on a printed circuit board finished with electroless nickel immersion gold (PCB-ENIG) under an adsorbed thin electrolyte layer (ATEL) were investigated in situ via the measurement of cathodic polarization curves, electrochemical impedance spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy to clearly elaborate the corrosion behavior of PCB-ENIG in the atmospheric environment. Results indicated that the cathodic process of PCB-ENIG under ATEL was dominated by the reduction of dissolved oxygen, corrosion products, and H2O. The cathodic current density of PCB-ENIG increased progressively with increasing RH. Moreover, its cathodic current density in the solution was greater than that under ATEL. This result demonstrated that the diffusion process was not the controlling step during the limiting reduction of cathodic oxygen. When the polarization potentials were located in a more negative region, the cathodic polarization current density gradually decreased under 75% and 85% RH. Notably, the anodic process became the controlling step in the extremely thin liquid film during the remainder of the experiment.展开更多
文摘The potential dependence of the faradaic impedance of carbon steels in 3.5% NaCl solution was measured by ac impedance technique. The polarization resistance, and also the cathodic protection efficiency obtained from weight loss, maximized at 0.70 V with respect to saturated Ag/AgCl electrode . Consequently, the potential at faradaic impedance maximum corresponds well to the optimum cathodic protection potential. The study asults showed that the ac impedance technique is a promising method for monitoring and determining the optimum cathodic protection potential.
文摘The corrosion-protective performance of plasma-polymerized (PP) coatings on pretreated aluminum substrates has been investigated by cathodic polarization curve measurement. The surface composition and electronic properties of the pretreated and PP film coated metal surfaces were also characterized by XPS and the temperature-programmed photoelectron emission (TPPE). A PP coating was prepared on the pretreated surfaces by plasma polymerization of a mixture of tetraethoxysilane (TEOS) monomer vapor and oxygen using a 13.56MHz radiofrequency generator. The polarization curve of PP film coated samples was measured in NaCl aqueous solution. The weight loss rate calculated from the value of the corrosion current of the curve was used to estimate the protective performance of the PP film coated samples. Argon plasma treatment of the metal surface gave much better corrosion-protective performance than pretreatments such as oxidation by heating in air and diamond scratching. The XPS analysis indicated that the silicon oxide assigned to SiO2 was formed on the PP film coated surface. The TPPE analysis revealed that the electron emission characteristics for the metal surfaces pretreated only were strongly influenced by the pretreatments, while all the PP film coated samples exhibited nearly the same electron emission trend with a much decreased intensity.
文摘A new cathode with Ti2 Ni alloys and Ni/Mo electrocatalyst has been developed for alkaline water electrolysis. The characterization for hydrogen evolution reaction (HER)is carried out in a 30 wt% potassium hydroxide (KOH) solution. The cathode shows a low hydrogen overpotential(η=60 mV at 70℃ in 30 wt% KOH) and ezcellent stability under conditions of continuous electrolysis and intermittent electrolysis with power interruption .
基金Project(51271032)supported by the National Natural Science Foundation of ChinaProject(2014CB643300)supported by the National Basic Research Program of ChinaProject supported by the National Environmental Corrosion Platform,China
文摘The effects of relative humidity (RH) on a printed circuit board finished with electroless nickel immersion gold (PCB-ENIG) under an adsorbed thin electrolyte layer (ATEL) were investigated in situ via the measurement of cathodic polarization curves, electrochemical impedance spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy to clearly elaborate the corrosion behavior of PCB-ENIG in the atmospheric environment. Results indicated that the cathodic process of PCB-ENIG under ATEL was dominated by the reduction of dissolved oxygen, corrosion products, and H2O. The cathodic current density of PCB-ENIG increased progressively with increasing RH. Moreover, its cathodic current density in the solution was greater than that under ATEL. This result demonstrated that the diffusion process was not the controlling step during the limiting reduction of cathodic oxygen. When the polarization potentials were located in a more negative region, the cathodic polarization current density gradually decreased under 75% and 85% RH. Notably, the anodic process became the controlling step in the extremely thin liquid film during the remainder of the experiment.
