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: 《中国腐蚀与防护学报》
Abstract: The synergistic corrosion inhibition effect related with inhibitors and synergistic agents was firstly introduced. Then the research progress of synergistic corrosion inhibition effect worldwide in recent years was summarized. The different synergistic combinations were classified into nine categories according to the sorts of corrosion inhibitors and synergistic agents, while the synergistic mechanisms were discussed. Furthermore, the research directions in the future on synergistic inhibition effect were prospected as well.
Subjects: Materials Science >> Materials Science (General) submitted time 2023-03-31 Cooperative journals: 《腐蚀科学与防护技术》
Abstract: The influence of crude oil on the inhibition performance of three corrosion inhibitors in H2S/CO2 containing brines was investigated by using dynamic mass loss method and potentiodynamic polarization technology. The crude oil could lower the inhibition efficiency of the water-soluble inhibitor significantly when its dosage was low, but have little impact when its concentration was high. The crude oil could also lower the inhibition efficiency of oil-soluble and water-dispersible inhibitor of different concentrations to some extent. The inhibition efficiency of oil-soluble inhibitor was declined in the presence of the crude oil significantly. By measuring the concentration of inhibitor in the water phase it follows that after the aqueous solution containing inhibitors was mixed with crude oil, most of the water- soluble inhibitor stayed in the aqueous solution; while most of the oil-soluble and water-dispersible inhibitor stayed in the aqueous solution and the rest went into the oil phase; and almost all of the oil-soluble inhibitor went into the oil phase.
Subjects: Materials Science >> Materials Science (General) submitted time 2023-03-31 Cooperative journals: 《腐蚀科学与防护技术》
Abstract: Corrosion behavior of epoxy coating induced by immersion in real seawater as well as immersion in 3.5%NaCl solution and salt spray in laboratory was characterized by means of electrochemical impedance spectroscopy (EIS). Then the relationship between the electrochemical impedance (|Z |0.01 Hz) of the coating tested in the two laboratory environments and that in seawater immersion test were analyzed. It follows that the degree of corrosion severity of the above three test environments could be ranked as: 3.5%NaCl solution<seawater immersion<salt spray. The salt spray test exhibited c.a. 2.3 fold stronger corrosivity for the epoxy coating, or say c.a. 2.3 acceleration effect on the corrosion of epoxy coating in comparison with the real seawater corrosion.
Subjects: Materials Science >> Materials Science (General) submitted time 2023-03-31 Cooperative journals: 《腐蚀科学与防护技术》
Abstract: Effect of Na2MoO4 and triethanolamine (TEA) on pitting corrosion inhibition of Q235 carbon steel was studied with methods of potentiodynamic polarization, microcell potential scanning, EIS and XPS etc. The results show that when Na2MoO4 is compounded with TEA the pitting potential Eb of the steel in 0.02 mol/L NaCl+0.1 mol/L NaHCO3 solution is obviously increased. Under an applied potential of 0.3 V, some potential peaks are observed at active sites on the surface, and the compound of Na2MoO4+TEA can effectively inhibit the number of the active sites and decrease the intensity of the potential peaks. In the solution with Na2MoO4 and TEA, the formed inhibition film on steel surface is composed of mainly Fe2(MoO4)3, Fe2O3 and TEA. The adsorption of TEA may improve the compactness of the inhibition films induced by Na2MoO4 and further increase the inhibition effect.
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: 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。