Subjects: Materials Science >> Materials Science (General) submitted time 2023-03-31 Cooperative journals: 《中国腐蚀与防护学报》
Abstract： The effect of strain on the pitting behavior of Q235 carbon steel in solutions of NaHCO3+ NaCl was studied by means of potentiodynamic polarization measurement, EIS and XPS. The results show that in a solution of 0.2 mol稬-1 NaHCO3+0.01 mol稬-1 NaCl, a strain of 8% leads to an obvious increase of the pitting potential Eb of Q235 steel, but as the Cl- concentration increased, the difference between the Eb values of strain and strain free samples decreased. When the Cl- concentration increased to 0.1 mol稬-1, the difference of Eb values disappeared. Besides, strain caused lower impedance, smaller charge transfer resistance Rct and decreased the ratio Fe3+/Fe2+ in the passive film, thereby reduced the stability of passive film. The phenomenon that strain caused the increase of Eb was attributed to that the strain promoted the anodic dissolution of Fe which in turn promoted the preferential adsorption of HCO3- on the surface, as the result the harmful effect of Cl- on the passive film was inhibited. As the ratio HCO3-/Cl- in the solution decreased, the effect of HCO3- decreased and finally disappeared.
Subjects: Materials Science >> Materials Science (General) submitted time 2023-03-31 Cooperative journals: 《腐蚀科学与防护技术》
Abstract： Corrosion behaviour of four cast magnesium alloys (ZK60, AM60, AZ31 and AZ91D) was investigated in a simulated body fluid (SBF) for 72 h by weight-loss method, as well as electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization measurements. Their surface morphology after immersion tests was observed by scanning electron microscopy (SEM). The results show that among the four alloys, AZ91D exhibits uniform corrosion with the lowest corrosion rate; AZ31 suffers serious pitting corrosion with the highest corrosion rate; while AM60 and ZK60 alloys exhibit similar corrosion behavior.
Subjects: Materials Science >> Materials Science (General) submitted time 2023-03-31 Cooperative journals: 《腐蚀科学与防护技术》
Abstract： The Effect of NO2- on the early stages of pitting corrosion of Q235 carbon steel in a simulated concrete pore solution (pH=11) was studied by means of polarization curves, Mott-Schottky curves and XPS methods. It was found that, NO2- inhibits both the stable pitting corrosion and the metastable pitting corrosion. The metastable pitting corrosion potential and the stable pitting corrosion potential increase with the increase of NO2- concentration and follow the similar trend. The nucleation process of pits can apparently be inhibited by a low content of NO2-, however this effect increases only slightly as the NO2- content higher than a critical value about 0.03 mol/L. With the increase of NO2- concentration, more Fe2 + in the passive film can be oxidized into Fe3 + and thereby, the defect density related with oxygen vacancies decreases, so the nucleation process of pits may be inhibited.
Subjects: Materials Science >> Materials Science (General) submitted time 2023-03-31 Cooperative journals: 《腐蚀科学与防护技术》
Abstract： A corrosion resistant coating for AZ91D magnesium alloy was prepared by adding pure magnesium particles, aluminium triphosphate (SAP) and ceria in an epoxy coating. The performance of the coating in 3%NaCl solution was studied with methods of Machu test, electrochemical impedance measurement and scanning electron microscope. The results show that the Mg-rich epoxy coating failed and the magnesium substrate was corroded after immersion for about 2000 h, while no corrosion was observed beneath the coating with SAP and ceria addition after immersion for 4448 h . Distinctly the added SAP and ceria can decrease the activity of magnesium particles in the Mg-rich epoxy and thereby prolong the life time of the coating. On the other hand, the compactness and the barrier property of the coating are improved as well.
Subjects: Materials Science >> Materials Science (General) submitted time 2017-03-31 Cooperative journals: 《腐蚀科学与防护技术》
Abstract：利用电化学阻抗、红外光谱、电镜等方法研究了8-羟基喹啉改善环氧富锌涂层性能的作用。在环氧富锌涂层中用5%的8-羟基喹啉替代锌粉后，锌粉的电荷转移电阻Rct增加，且锌粉/溶液界面双电子层电容Qdl降低，锌粉的反应过程被抑制，因此，虽然锌粉的含量降低了，但是锌粉的阴极保护作用时间却明显延长。另一方面，8-羟基喹啉改性后的环氧富锌涂层的电阻Rc升高，电容Qc降低，涂层孔隙率P降低，涂层的屏蔽性增强。上述两方面的作用，可以显著改善涂层的保护性能，延长涂层寿命。
Hits
Hits
Downloads
Comment