Search results

The purpose of this paper is to study the variations of composition and properties of the passive film on 316 L stainless steel surface in 80°C, 0.5 mol L-1 H2SO4 + 2 mg L-1 NaF solution, is helpful to understand the mechanisms of corrosion resistancethe of plated Pd on 316 L ss.

The variations of composition and properties of the passive film on 316 L stainless steel surface in 80°C, 0.5 mol L-1 H2SO4 + 2 mg L-1 NaF solution after connected to Pd electrode were studied with methods of potential monitor, X-ray photoelectron spectroscopy analysis and electrochemical impedance spectrum (EIS) measurement.

By connecting to a Pd electrode, the potential of the SS sample increased from the active region to the passive region. By connecting to the Pd electrode, the contents of Cr, Cr(OH)3 and Fe3O4 in passive film increased obviously. With increased Pd/SS area ratio, the Cr(OH)3 content in passive film increased but the Fe3O4 content changed little. The results show that after connecting to Pd the corrosion resistance of the passive film on 316 L stainless steel increases obviously, which may be attributed to the more compact passive film because of higher Cr, Cr(OH)3 and Fe3O4 contents and less point defects in the film.

The effects and mechanism of Pd on passivation of SS was studied.

The purpose of this paper is to study the influence of Zr content on immersion and electrochemical corrosion behavior of Zr-containing Ti-based (TiZr) alloys.

The phase analysis of as-cast TχZAB alloys was carried out using X-ray diffraction. The microstructure of corrosion surfaces of the samples was observed using optical metallographic microscopy and scanning electron microscopy, equipped with energy dispersive spectroscopy.

The immersion test reveals that the corrosion is alleviated in the presence of a high amount of Zr, whereas pitting corrosion occurs when the Zr content is up to 40 Wt.%. Furthermore, the electrochemical analysis demonstrates that the corrosion resistance TiZr alloys is improved with increasing Zr content.

The TiZr alloys are promising candidates for high-end applications because of their excellent comprehensive properties. These alloys are usually used in marine or other harsh corrosive environments; therefore, it is essential to study their corrosion behavior.

The purpose of this study was to investigate the effects of deformation-induced martensite on electrochemical corrosion behaviors of 304 austenitic stainless steel in a simulated primary water environment of a pressurized water reactor nuclear power plant with boric acid and lithium hydroxide contaminated with chloride by potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), Mott–Schotty curves and X-ray photoelectron spectroscopy (XPS).

The effects of deformation-induced martensite transformation on electrochemical corrosion behaviors of 304 austenitic stainless steel was investigated in a simulated primary water environment of a pressurized water reactor nuclear power plant with boric acid and lithium hydroxide contaminated with 0.1 M Cl⁻ by potentiodynamic polarization, EIS, Mott–Schotty curves and XPS in this paper.

The results revealed that the martensitic phase contents increased with the level of cold deformation. The general corrosion current density and the corrosion potential increased and decreased, respectively, with the increase of cold deformation degree. However, the pitting potential decreased as the cold deformation increased up to 20 per cent, then a slight increase was observed at 35 per cent cold working. It was found from Mott–Schottky curves and XPS analysis that as the cold deformation degree increased from 0 to 35 per cent, the doping concentrations of the oxide films increased; however, the film thickness decreased, which indicates that both density and integrity of the films are degraded significantly as the deformation degree increases, and this ultimately contributes to the significant increment of the general corrosion rate and reduction of the pitting corrosion resistance.

The effects of deformation-induced martensite transformation on electrochemical corrosion behaviors of 304 austenitic stainless steel was investigated in a simulated primary water environment of a pressurized water reactor nuclear power plant with boric acid and lithium hydroxide contaminated with 0.1 M Cl⁻ by potentiodynamic polarization, EIS, Mott–Schotty curves and XPS in this paper.

Coral aggregate seawater concrete (CASC) is a new type of lightweight aggregate concrete that is becoming widely used in reef engineering. To investigate the corrosion behavior of different kinds of rebar in CASC exposed to simulated seawater for 0-270 d, the electrochemical techniques, including linear polarization resistance (LPR) technique and the electrochemical impedance spectroscopy (EIS), were used in the present work.

The electrochemical techniques, including LPR technique and the EIS, were used in the present work.

Based on the time-varying law of linear polarization curves, self-corrosion potential (E_corr), polarization resistance (R_p), corrosion current density (I_corr), corrosion rate (i), and the characteristics of EIS diagrams for different types of rebar in CASC, it can be found that the anti-corrosion property of them can be ranked as epoxy resin coated steel > 2205 duplex stainless steel (2205S) > 316 L stainless steel (316 L) > organic coated steel > ordinary steel. Additionally, the linear regression equation between R_p and charge transfer resistance (R_ct) was established. Finally, the EIS corrosion standard of rebar was established from the LPR corrosion standard, which provides a direct standard for the EIS technique to determine the condition of rebar in CASC.

The linear regression equation between polarization resistance and charge transfer resistance was established. And the EIS corrosion standard of rebar was established from the LPR corrosion standard, which provides a direct standard for the EIS technique to determine the condition of rebar in CASC.

High-silicon chromium iron (HSCI) has been used in ground grids in southern China, while there was a lack of study on its corrosion behavior in this soil environment. The purpose of this paper is to discover the corrosion of HSCI in acidic and alkaline soil solutions.

The original defects on the HSCI surface were observed using optical microscopy, and the corrosion behavior of the HSCI in the acidic and alkaline soil solutions were jointly detected using electrochemical measurements and scanning electron microscopy/energy dispersive spectrometer.

The results showed the corrosion rates of the HSCI in the acidic and alkaline soil solutions were limited, and the high contents of Cr and Si in matrix was responsible for its high corrosion resistance. The HSCI showed a similar corrosion tendency in the two solutions, while its corrosion rate in the acid soil solution was higher than that in the alkaline soil solution. The corrosion pits on the specimen surface were originated from the original defects in matrix, and the edges of the corrosion pits were more rounded than the original defects after 720 h immersion in the two solutions. The original defects in the HSCI matrix played a significant role in the corrosion process.

The paper discovered the corrosion evolution of HSCI in the acidic and alkaline soil solutions. What is more, the acceleration role of the original defects on the corrosion of the HSCI in the acidic and alkaline soil solutions was discovered in the paper. The results are beneficial for the material selection of ground grid equipment in engineering.

The purpose of this paper is to study the effect of thermal treatment on the corrosion protection of steel by using poly(3-hexylthiophene) (P3HT) and P3HT/PS(polystyrene) or P3HT/PMMA(polymethyl methacrylate) blends coatings in sulfuric acid solution.

The polymer coatings were thermally treated at two different temperatures (100 and 200°C, respectively) and were compared with the polymer coatings dried at room temperature in their application as protective coatings against corrosion of A36 steel. The corrosion resistance of polymer coatings-covered steel substrates was evaluated by using potentiodynamic polarization curves and linear polarization resistance.

At 25 and 100°C, polymer coatings showed a better protection of the A36 steel, and the corrosion rate diminished in three orders of magnitude with regard to the bare steel. Morphological study showed that the increased temperature benefited the integration of the two polymeric phases; however; the temperature of 200°C affected the film quality, generated cracks and holes, which affected the barrier properties of the coatings.

The research involved the synthesis and physicochemical characterization of the polymeric coatings (P3HT, PS/P3HT y PMMA/P3HT), as well as their application as coatings in the steel to prevent corrosion. The effect of thermal treatment of the protective coatings on steel corrosion was studied.

This paper aims to contribute to reducing the problem of metal corrosion through the use of polymer coatings.

Today, majority of metal surfaces are subject under the protection to prevent a very common phenomenon, that is corrosion. Corrosion is the result of chemical reactions that occur between a metal or a metal alloy and its environment. Corrosion creates a degradation of the material that has an impact on some economic, environmental and even social aspects, here the great importance of its protection.

It is shown in this study that the P3HT coating provides better corrosion protection of the A36 steel than the PS and PMMA coatings. However, mixtures of P3HT with PMMA and PS protected the steel from corrosion by two and three orders of magnitude similar to the simple P3HT coating. Polymer blends improved adhesion to the substrate and mechanical property of the coating, and in addition, the polymer blends made cheaper coating.

This paper aims to study the effect of current density of hydrogen charging on the semiconductor properties and pitting initiation of 2205 duplex stainless steel (DSS) passivation film.

In this work, the 2205 DSS is pre-hydrogenated and passivated. Then, the passivation film is tested by electrochemical impedance method, Mott–Schottky curve method and dynamic potential scanning method. The influences of hydrogen on the properties of the passivation film and the corrosion behavior of the matrix were studied by analyzing the curves obtained in the electrochemical test. The surface of the passivation film after pre-hydrogenation and anodic polarization was observed by using the ultra-depth three-dimensional microscopy and the scanning electron microscope. The integrity, density and corrosion morphology of the passivation film were studied and discussed.

With the increase of the hydrogen current density, the growth of the passivation film is hindered, the concentrations of donor and acceptor in the film are increased, the conductivity of the passivation film increases. In the anodic polarization, the dimensional passive current density increases with the increase of the hydrogen current density, and the pitting potential is reversed, the more likely the sample is pitting. In general, hydrogen hinders the formation of the passive film on duplex stainless steel, which increases the concentration of point defects in the passive film. Finally, the passive film is easy to crack and pitting.

The performance of passive film is an important condition to influence the corrosion behavior of stainless steel. However, little research has been done on the effects of hydrogen on the electrochemistry and pitting sensitivity of 2205 DSS passivation films. The effect of hydrogen on semiconductor properties and pitting initiation of 2205 DSS passivation film is needed to be investigated.

This paper aims to study the influence of NaNO₂ on the chemical composition of passivation film.

X-ray photoelectron spectroscopy and X-ray diffraction were selected to determine the composition of passivation film of steel bars in mortar. The specimens were exposed to the chloride solution, carbonation environment and the coupling effects of chloride solution and carbonation. The chemical composition and micro structures at 0 and 5 nm from the outer surface of the passivation film of steel bars were analyzed.

Results showed that the nitrite inhibitor improved the forming rate of the passivation film and increased the mass ratio of Fe₃O₄ to FeOOH on the surface of steel bars. The component of Fe₃O₄ at 5 nm of the steel passivation film was more than that at 0 nm. Sodium ferrite in the pore solution was easily hydrolyzed and then FeOOH was formed. Therefore, due to the nitrite inhibitor, a “double layer structure” of the passivation film was formed to prevent steels bars from corrosion.

This is original work and may help the researchers further understand the mechanism of rust resistance by nitrite inhibitor.

The purpose of this paper is to fill the knowledge gap in the microscopic origin of high corrosion resistance in the passivated 316 L stainless steel.

Here, the pitting corrosion potential of the passivated 316 L stainless steel is measured, as well as the non-passivated one. Using the aberration-corrected scanning transmission electron microscopy, the microstructure of the passive film is unambiguously revealed. Combining the electron energy loss spectroscopy with the X-ray photoelectron spectroscopy, the depth profiling analysis is conducted and the variations in composition from the very surface of the passive film to the internal steel are clarified.

By optimizing the passivation treatment process, the authors significantly increase the pitting corrosion potential of the passivated 316 L stainless steel by 300 mV, compared with the non-passivated one. The passive film features a unique amorphous multilayer structure. On the basis of the depth profiling analysis, the origin of the high corrosion resistance achieved is unraveled, in which the redistribution of elements in the multilayer passive film, especially the enrichment of Cr in the topmost layer and Ni at the film-metal interface, prevent the oxidization of the inner iron of the steel.

This study advances understanding of the nature of the passive film from a microscopic view, which can be helpful for the further improvement of the corrosion resistance performance.

This study introduces a model for the multilayer structure of passive films that reveals the reconstitution of the passive films after the opportune passivation treatments. Due to the redistribution of elements caused by passivation, the enrichment of Cr in the outer layer and Ni near the film-metal interface leads to enhance corrosion resistance performance.

The purpose of this work is to reveal the mechanism of WO₄²⁻ on surface passivation for Q235 carbon steel in tungstate solution.

In Na₂WO₄ solutions with the different concentrations of WO₄²⁻, the spontaneous passivation occurred on the surface of Q235 carbon steel when the concentration of WO₄²⁻ was up to 0.13 mmol/L, which was attributed to the formations of the inner deposition film and the outer adsorption film on the Q235 surface under the action of WO₄²⁻.

The inner deposition film presented a two-layer microstructure: the inside layer was composed of Fe₂O₃ mainly, and the outside layer comprised Fe(OH)2•nH₂O, Fe(OH)3•nH₂O, FeWO₄ and Fe₂(WO₄)3.

Both FeWO₄ and Fe₂(WO₄)3 repaired the defects in the outside layer of the inner deposition film; however, the outer adsorption film played a more important role in the surface passivation than the inner deposition film did.