Corrosion Resistance Of Passive Film Research Articles

The Effect of Potential on Surface Characteristic and Corrosion Resistance of Commercial Pure Titanium Processed by Anodic Oxidation Treatment

Anodic oxidation treatment of commercial pure titanium was carried out at the voltage of 30, 50 V in 0.5 M H2SO4 solution so as to obtain the effects of the anodic potential on the surface characteristic and corrosion resistance of passive film. The morphology and corrosion resistance of the treated samples were investigated using scanning electron microscopy (SEM), atomic force microscope (AFM), X-ray photoelectron spectroscopy (XPS), potentiodynamic polarization curves and electrode impedance spectroscopy (EIS). The results show that increasing anodic potential can significantly enhance the corrosion resistance of commercial pure titanium.

Effect of martensite transformation on chemical composition, semiconductor property and corrosion resistance of passive film on SAE 304 stainless steel

Effect of martensite transformation on chemical composition, semiconductor property and corrosion resistance of passive film on SAE 304 stainless steel

Enhancements of Passive Film and Pitting Resistance in Chloride Solution for 316LX Austenitic Stainless Steel After Sn Alloying

In the present work, the electrochemical behavior and properties of the passive film of a new Sn-alloyed 316LX austenitic stainless steel were investigated. With the increase in Sn content in 316LX austenitic stainless steel from 0 to 0.21%, the critical pitting temperature value increased from 32.6 to 38.8 °C, and the pitting potential increased from 0.252 VSCE to 0.317 VSCE. Electrochemical impedance spectroscopy results showed that the corrosion resistance of passive film rose with the increase in Sn content, indicating a more stable passive film. The Mott–Schottky measurement revealed an n-type passive film with a decreased carrier concentration on the 316LX austenitic stainless steel surface. The Cr, Sn2+ and Sn4+ (SnO, SnOHCl or SnO2) enrichments were observed in the passive layer by X-ray photoelectron spectroscopy. The enrichment of Sn and Cr in the passive film can account for the enhanced pitting resistance of 316LX austenitic stainless steel in chloride solution.

Effect of Corrosion Inhibitors on Chromate-free Passivation of Hot-Dip Galvanized Steel

Commercially available passivation methods for white-rust protection of Hot-Dip Galvanized steel have been applied for chromate passivation. However, hexavalent chromium (Cr-VI) is highly toxic and carcinogenic. Therefore, in this paper, we put forth a new means for white-rust protection of Hot-Dip Galvanized steel based on the effects of corrosion inhibitors. In this study, the passivation solution combines the advantages of inorganic salt passivation, silane passivation and resin passivation. The corrosion resistance of the inorganic and organic composite passivation films with corrosion inhibitors was determined by a neutral salt spray test and electrochemical Tafel polarization curves. The surface chemistry of the coatings was monitored by scanning electron microscopy (SEM), X-ray Photoelectron spectroscopy (XPS) and Fourier transform infrared reflection absorption spectroscopy (FTIR). And further studying on the formation mechanism of the passivation film was carried out. The SEM indicated that the top surface of the passivation film was transparent, smooth, uniform and compact. The XPS and FTIR results showed that the passivation film consisted mainly of organic functional groups including-(CH2)n-, -OH, N-H, C=O, C-Si, C-O-C, C-N, Si-O-Si, Si-O-C and so on. The corrosion resistance of passivation film with corrosion inhibitors was significantly improved than that of the passivation film without corrosion inhibitor. After 96h of the corrosion test, the corrosion area was found to be less than 5 %, which indicated that the passivation film greatly improved the corrosion resistance of the hot-dip galvanized sheet, and exhibited a very good protective effect so that can met some industrial applications.DOI: http://dx.doi.org/10.5755/j01.ms.24.3.16330

Electronic properties and corrosion resistance of passive films on austenitic and duplex stainless steels

Passive films were grown at constant potential in acidic (pH∼2) and alkaline (pH∼13) solutions on chromium, AISI 304L, AISI 316L and Duplex stainless steels. Passive films on chromium grow following a high field mechanism considering the presence of dissolution phenomena. According to the photoelectrochemical characterization, passive films on Cr have a bandgap of 3.4 eV when formed in acidic solution, and of 2.4 eV when formed in alkaline solution due to the formation of Cr(OH)3. These films result to be poorly stable against anodic dissolution due to a very anodic flat band potential. Conversely, impedance and photoelectrochemical measurements proved that passive films on stainless steels are chromium rich oxide n-type semiconductors with a very high polarization resistance. Their band gap depends on the pH of the passivation solution and on the SS composition.

Passivity of stainless steel in sulphuric acid under chemical oxidation

ABSTRACTThe main purpose of the present work was to study the passivity of stainless steel in sulphuric acid under chemical oxidation with H2O2 solution. Potentiodynamic polarisation and open circuit potential (OCP) measurements indicated that H2O2 facilitates the increase of OCP of stainless steel which shifts from active region into passive region. The X-ray photoelectron spectroscopy results suggested that a passive film, composed of oxyhydroxides, Cr2O3, Cr(VI) species, NiO, and sulphate (FeSO4, Cr2(SO4)3·xH2O), is achieved after H2SO4–H2O2 passivation. The passive mechanism under H2O2 oxidation was discussed and the corrosion resistance of passive film was compared with that of the passive films produced by HNO3 passivity and H2SO4 potentiostatic passivity. The results of electrochemical impedance spectroscopy, cyclic voltammetry, and anodic polarisation experiments confirmed that the chemical oxidation with H2O2 solution is capable of improving the corrosion resistance of stainless steel significantly and the passive film is more stable than those produced by other passivating methods.

Corrosion Behavior of Carbon Steel Under Environment Simulated inside of Concrete Containing Chloride Ion

Many infrastructures such as expressways and buildings were constructed in Japan between the 1950s and the 1970s. There is greatly influence of airborne sea salt on corrosion in Japan surrounded by the sea, and reinforcement corrosion is accelerated by rainfall, dew condensation and water absorption of airborne sea salt. Therefore, many of these infrastructures are in a condition requiring repair or renewal in the present. In this study, electrochemical measurements of carbon steel were conducted in an aqueous solution simulated the inside of concrete, in order to investigate corrosion behavior of reinforcing bars in concrete. In addition, the influence of surface condition of the reinforcing bars before corrosion on their corrosion resistance was examined by the corrosion monitoring using an electrochemical impedance method. Carbon steel and 0.1% Ca(OH)2 solution were used as the sample for the reinforcing bar in concrete and as the test solution simulating the internal environment of the concrete, respectively. The corrosion resistance of passive film in concrete was investigated by anodic polarization measurement and electrochemical impedance measurement. The passive film region was observed regardless of concentration of chloride ion in the test solution. The current density in the test solution containing 0M and 0.01M of chloride ion did not abruptly increase in the passive state region and local corrosion such as pitting corrosion did not occur on the steel surface. A sharp rise in current density was observed in the test solution containing 0.1M or more of chloride ion. The anodic polarization curves of carbon steel with passive film formed by immersion in the test solution was measured, in order to investigate the influence of the film formation period on the properties of passive film. A passive region was observed in the anodic polarization curves of all samples. The passive current density decreased with an increase of immersion time, indicating that the corrosion resistance of the passive film improved as the immersion time increased. Furthermore, the electrochemical impedance measurements of carbon steel passivated in the test solution were carried out. The impedance characteristic can be represented by a typical Randles type equivalent circuit, and the diameter of the semicircle corresponds to the film resistance. The film resistance increased in proportion to the immersion time in the test solution. This result is consistent with the result of the anodic polarization measurement.

Investigating the influence of hydrogen on stress corrosion cracking of 2205 duplex stainless steel in sulfuric acid by electrochemical impedance spectroscopy

AbstractAs a nondestructive and sensitive method, electrochemical impedance spectroscopy (EIS) can be used to investigate the passivation and breakdown of passive films on steel. In this study, EIS, combined with slow strain rate test and scanning electron microscopy, was employed to study the stress corrosion cracking (SCC) behavior of 2205 duplex stainless steel in 0.5 m sulfuric acid solution under hydrogen-charging conditions. Results showed that the corrosion resistance of passive film on the hydrogen-charged specimen was lower than that for the specimen with no hydrogen charge. Hydrogen-induced cracking was evident after the specimens had been charged for 24 h. The phase shift in EIS, calculated from frequencies between 0.1 and 10 Hz, could be used to monitor the SCC process.

Corrosion Resistance of Passive Films on Orthodontic Bands in Fluoride-Containing Artificial Saliva

Corrosion Resistance of Passive Films on Orthodontic Bands in Fluoride-Containing Artificial Saliva

Characterization of a Stressed Passive Film Using Scanning Electrochemical Microscope and Point Defect Model

The corrosion resistance of passive film is investigated by in situ scanning electrochemical microscopy (SECM), and is also diagnosed by modified point defect model (PDM). Thus the constant rate related to defect reactions present in the passive film, can be obtained. SECM results indicate that both compressed and tensile stress decreases the stability of passive film, leading to an increase in surface reactivity and dissolution rate—which is possibly due to the decreased binding force between atoms caused by the stress and therefore make them more easy to dissolve. PDM results indicate that the reason of the decreased stability is an increase in the rate constant of defect reactions present in the passive layer, including transportation rate of oxygen and cation dissolution rate.

Surface corrosion enhancement of passive films on NiTi shape memory alloy in different solutions

The corrosion behaviors of NiTi shape memory alloy in NaCl solution, H2SO4 solution and borate buffer solution were investigated. It was found that TiO2 in passive film improved the corrosion resistance of NiTi shape memory. However, low corrosion resistance of passive film was observed in low pH value acidic solution due to TiO2 dissolution. Moreover, the corrosion resistance of NiTi shape memory alloy decreased with the increasing of passivated potential in the three solutions. The donor density in passive film increased with the increasing of passivated potential. Different solutions affect the semiconductor characteristics of the passive film. The reducing in the corrosion resistance was attributed to the more donor concentrations in passive film and thinner thickness of the passive film.

Semiconducting behavior of pure copper in alkaline solutions

The corrosion resistance of passive film is correlated with its semiconducting properties, which can be measured by the Mott–Schottky analysis in high frequency domain. In this study, the semiconducting behavior of passive films formed on pure copper in aqueous NaOH solutions was investigated using Mott–Schottky analysis. The polarization curves suggested that pure copper shows comparable passive behavior in NaOH solutions with different concentrations. Also, the potentiodynamic polarization curves showed corrosion current densities reduction with decrease in concentration of NaOH solutions. In Mott–Schottky analysis, no evidence of n-type semiconducting behavior was found, indicating that oxygen vacancies and copper interstitials do not have a significant population density in the passive film. Also, this analysis indicated that with the decrease of NaOH concentration in the solution, the acceptor density of passive films increases.

The effects of grain refinement and deformation on corrosion resistance of passive film formed on the surface of 304 stainless steels

The nano/ultrafine grained stainless steel promoted the form of more deformation nanotwins and inhibited dislocation slip and strain induced α′-martensite transformation during deformation compared with coarse grained stainless steel. The diffusivity of the point defects in passive film in coarse grain stainless steel was lower than that in nano/ultrafine one. The corrosion resistance of nano/ultrafine grained stainless steel was improved by reducing content of strain induced α′-martensite. Moreover, the donor and acceptor densities in passive film formed on the stainless steel increased due to more strain induced α′-martensites and more chloride ions. Fewer strain induced α′-martensites and more nanotwins in nano/ultrafine grained stainless steel improved its corrosion resistance.

Effect of Pentaerythritol Glycoside on Performance of Passive Film Formed on Steel Rebar in Saturated Ca(OH)2 Solution Containing 3.5%NaCl

The effect of PG(pentaerythritol glycoside) on the performance of the passive film on steel rebar in Ca(OH)2saturated solution containing 3.5%NaCl, which was designed to simulate solutions in concrete pores, was investigated by mean of polarization curve measurement, MottSchottky analysis technique and surface analysis. The results showed that the PG could enhance the stability of the adsorption film formed on the metal surface. The curves of Csc-2vs E of the steel rebar electrodes follow a linear Mott-Schottky(M-S) relationship with a positive slope in the range of potential from-0.5 to-0.1 V(vs SCE) in the M-S measurements, suggesting the passive film formed on the steel rebar surface was n-type semi-conductor. Moreover, with increasing concentration of inhibitor, the carrier density in passive film decreases, indicating that the passive film formed on steel rebar surface in the presence of PG was more compact and stable rather than that in the absence of inhibitor, and the corrosion resistance of passive film is gradually enhanced.

Effect of aluminium on the passivation of zinc–aluminium alloys in artificial seawater at 80 °C

The effect of Al (0.15, 0.3 and 1.0wt.%) on the passivation of Zn–Al alloys in artificial seawater at 80°C is investigated by electrochemical measurements, scanning electron microscopy (SEM) and X-ray diffraction (XRD). It is found that the presence of Al in Zn–Al alloys can retard passivation. Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) measurements show that Al increases the current density but decreases the corrosion resistance of passive films, respectively. Mott-Schottky analysis reveals that Al increases the electrical conductivity and the capacitance of the films. Passivation of Zn–Al alloys occurs in artificial seawater when the immersion time is between 120 and 288h, due to the presence of various Zn and Al protective compounds at the surfaces. Depassivation occurs when the immersion time is between 288 and 720h, probably due to the decrease of solution pH and the Cl− penetration mechanism.

Passivator Composition of Rich of Phytic Acid Used for Brass-Strip

Passivator components of phytic acid, hydrogen peroxide, boric acid and polyethylene glycol was optimized by orthogonal experiment. Corrosion resistance of passivation film of brass-strip was invertigated by salt spraying, weight loss and electrochemical test. The results show that the optimization passivator consists of phytic acid (50% mass fraction) 8ml/L, hydrogen peroxide (mass fraction 30%) 30ml/L, boric acid 5g/L, polyethylene glycol 15ml/L and additive 4g/L. Corrosion current density and corrosion rate of the brass-strip specimens coated by rich-phytic acid passivator are similar to that treated by traditional sodium dichromate passivator, the characteristic of anti-tarnish slightly better than that coated by sodium dichromate passivator. The feature of rich-phytic acid passivator is environmental protection.

The Study about Environmentally-Friendly Passivation Technology Process and Performance on Brass Surface

The paper through the synergy before mixed Phytic acid and Sodium molybdate, Sulfosalicylic acid, Organic silane, and add the active substances PEG, Optimize the Passivation liquid formula of Brass surface, Phytic acid is the main ingredient, study the affection of Phytic acid Passive film Corrosion resistance on the three main Passivation conditions: Passivation temperature, time and Passivation solution PH value. The results show that，Phytic acid passivation film process recipes as follows：Phytic acid (quality score 50%) 2~5ml/L, sodium molybdate 4~8g/L, organic material 10~30ml/L, sulfosalicylic acid 3~7g/L, polyethylene glycol 2~6g/L, deactivated temperature 30~35°C, pH value 5, deactivated time 60s. The test showed that，the phytic acid passive film can obviously enhance the anti-corrosive performance on the brass surface, its corrosion resistance proportion chromates passive film is fairly good.

The semi-conductor property and corrosion resistance of passive film on electroplated Ni and Cu–Ni alloys

Mott–Schottky analysis, electrochemical impedance spectroscopy in conjunction with the Point Defect Model (PDM), were performed to characterize the semi-conductor property of passive films formed on Cu–Ni alloys in 1 mol/L NaOH solution. The acceptor density, flat potential and vacancy diffusion coefficient in the passive films formed on Cu–Ni alloys were determined. Results indicated that the passive films displayed p-type semi-conductive characteristics, where metal vacancies (over oxygen vacancies and interstitials) preponderated. With the increase of Cu, the flat potential moved towards positive, while the acceptor density and impedance of passive films decreased due to its steady oxidation-from Cu(I) to Cu(II), which increased the susceptibility to corrosion. In addition, the acceptor density and flat potential increased when the formation potential moved towards negative. The calculated value obtained for D 0 was around 10 −14 cm −2 s −1.

Effect of hydrostatic pressure on the nature of passive film of pure nickel

AbstractThe effect of hydrostatic pressure on the nature of passive film of nickel in 3.5% NaCl solution was investigated by means of polarization curves, electrochemical impedance spectroscopy (EIS), and Mott–Schottky measurement. The experimental results revealed that hydrostatic pressure had two opposite effects on passive film of nickel. On one hand, hydrostatic pressure improved the corrosion resistance of passive film of nickel such as the decreased acceptor density. On the other hand, the passive film became unstable and showed a higher diffusivity of acceptor density with the increasing of hydrostatic pressure, which deteriorated the corrosion resistance of passive film of nickel. The deterioration effect had greater influence on the passive film than the improvement effect, which led to the decreasing corrosion resistance of passive film with the increasing of hydrostatic pressure.

The Semiconductor Character of Passive Film of 304L Stainless Steel(SS), 316L SS and Nickel Alloy 800 Formed in Zinc Contained High-Temperature and High-Pressure Water

The semiconductor properties of passive film formed on 304L stainless steel (SS), 316L SS and Alloy 800HT in high-temperature and high-pressure water with zinc addition have been investigated by using Polarization curve, Mott-Schottky analysis and photocurrent method. The donor density, flat band and band gap of semiconductor behavior are analyzed to investigate the impact of zinc addition to the passive film. Analysis of the experimental results indicated that passive film formed on 316L and 800HT with zinc addition showed different electrochemical, photo-electrochemical and semiconductor properties. The results indicated that corrosion resistance of passive film from in high-temperature and high-pressure water with zinc addition was obviously better than that without zinc addition.