Passivation Of Stainless Steel Research Articles

Investigation of the passive film of nanocrystalline 304 stainless steel in 3.5 wt% NaCl solution under hydrostatic pressure

In this paper, the effect of hydrostatic pressure on the passive film of coarse crystalline 304 stainless steel (304 SS) and sputtered nanocrystalline stainless steel (304 NC) in 3.5 wt% NaCl solution has been investigated using in-situ electrochemical measurement techniques. The results indicate that nanosizing promotes the growth of the passive film. Hydrostatic pressure changes the nucleation mechanism of the passive film, decreases the carrier density and oxygen vacancy diffusivity, and decreases the content of oxides and hydroxides within the film, significantly deteriorating the corrosion resistance of the passive film. The point defect model (PDM) was introduced to elaborate the microscopic process of the surface passivation of stainless steel under hydrostatic pressure.

Effect of Al and Si addition on passivation of stainless steels in H2SO4 solution

The dissolved masses of Fe, Cr, Al, and Si in H2SO4 solution during the polarization of Cr-containing steels were quantified by online ICP-OES. The active dissolution current on 11Cr-2Al/-2Si was smaller than that on 11Cr due to the enrichment of Al/Si on the steel. The Cr dissolution from 11Cr2Al was suppressed in passive state, while that from 11Cr2Si was decreased in active-passive transition because accumulated Al or Si products have different physicochemical effects on the Cr-enrichment of the surface. Roles of Al/Si in corrosion process, especially passivation, were discussed based on quantitative analysis of dissolution products detected by ICP-OES.

Stainless Steel-Like Passivation Inspires Persistent Silicon Anodes for Lithium-Ion Batteries.

Passivation of stainless steel by additives forming mass-transport blocking layers is widely practiced, where Cr element is added into bulk Fe-C forming the Cr2 O3 -rich protective layer. Here we extend the long-practiced passivation concept to Si anodes for lithium-ion batteries, incorporating the passivator of LiF/Li2 CO3 into bulk Si. The passivation mechanism is studied by various ex situ characterizations, redox peak contour maps, thickness evolution tests, and finite element simulations. The results demonstrate that the passivation can enhance the (de)lithiation of Li-Si alloys, induce the formation of F-rich solid electrolyte interphase, stabilize the Si/LiF/Li2 CO3 composite, and mitigate the volume change of Si anodes upon cycling. The 3D passivated Si anode can fully retain a high capacity of 3701 mAh g-1 after 1500 cycles and tolerate high rates up to 50C. This work provides insight into how to construct durable Si anodes through effective passivation.

Surface Characterization on Electrophoretic Deposition Oof 316l Stainless Steel with Dissolved Chitosan for Biomedical Application

<span lang="EN-US">Of many compounds materials, </span><span lang="PT-BR">metallic biomaterial is widely used in human medical devices. An implant material's corrosion resistance impacts its flexibility and longevity. This corrosion resistance is also an important consideration for biocompatibility. This biomaterial contains stainless steel whcih may corrode after being installed in the human body since the passivity of stainless steel disappears when it is exposed to acids in the human body for a long duration. In addition, lacks of oxygen inhibits the formation of a new Cr<sub>2</sub>O<sub>3</sub> layer for corrosion protection. Based on this phenomenon, an advance treatment is required to improve the resistance corrosion of implant. This study investigates the effect of the concentration and duration of chitosan on the thickness and corrosion resistance of biomaterials. The concentration of chitosan used was 0.08</span><span lang="PT-BR">%, 0.16</span><span lang="PT-BR">%, and 0.24</span><span lang="PT-BR">% while the voltage used was constant at 10 V. The test results demonstrated the lowest corrosion rate occrured for 0.24 % chitosan concentration with 30 minutes coating duration. The lowest corrosion rate achieved was 0.014 mmpy and the maximum thickness was 75.4 μm. This study could be then used as a new solution to increase the safety of existing implants using biodegradable and non-toxic compounds. The next experiment should be implantation in real human body.</span>

Can We Enhance Passivity with a Surface Finish? Spectroscopic and Electrochemical Analysis on 316L Stainless Steel

The effects of surface finish by mechanical polishing, vibratory polishing, and high-temperature annealing were studied on 316L stainless steel by combining microscopic and spectroscopic analysis of the surface morphology and composition and electrochemical analysis of the corrosion resistance. Compared to mechanical polishing, vibratory finishing promotes passivity at the active-passive transition in acid solution and enhances resistance to chloride-induced passivity breakdown. Cr and Mo enrichments in the native oxide film increase owing to preferential iron etching. The bilayer structure develops a thicker Cr(III) oxide inner barrier layer and an outer exchange layer further enriched in Cr(III) hydroxide and Mo(IV/VI) oxides. The Fe-rich weak sites of passivity are reinforced. High-temperature annealing in reducing hydrogen environment enables us to fully reconstruct the cold-worked layers left by mechanical or vibratory finishing, thus allowing us to expose the bulk microstructure at the topmost surface. The benefits brought by vibratory finishing are lost upon reducing the initial native oxide. The re-formed native oxide develops a bilayer structure with similar Cr and Mo enrichments as that obtained from mechanical polishing and no beneficial effects on passivity. The results provide comprehensive insight into how the passivity of stainless steel can be enhanced by surface enrichment engineering.

Data on the effect of Ibuprofen drug derivative on 430T1 stainless steel in acid solutions

The anti-corrosion performance of Ibuprofen (IP) on 430T1 stainless steel samples exposed to 0.5 M H2SO4 solutions was evaluated employing electrochemical techniques. The results obtained validated the inhibitive performance of this compound, and the compound efficiency increased with increasing its concentration. The compound enhances the stainless steel passivation with an increased repression rate of the critical current. The inhibited samples show the lowest corrosion rate and high inhibition efficiency in comparison to the uninhibited samples. Tafel curves suggested that the IP mitigate both the cathodic and anodic reactions simultaneously. The adsorption of Ibuprofen was found to obey Freundlich’s adsorption isotherm. It is concluded that IP improved the stainless steel corrosion protection considerably.

Development of a Process for Applying Cerium-Containing Protective Coatings to Alloy Steel

A solution has been developed for deposition of cerium-containing coatings on an alloy steel base that meets the requirements for protective coatings. It is established that the protective coating on alloyed steel consists of cerium oxides Ce2O3 and CeG2, iron oxide Fe2O3, and chromium oxide Cr2O3. Passivation of stainless steel in a cerium-containing solution has been shown to significantly increase its resistance to pitting corrosion.

Effect of hydrogen on semiconductor properties and pitting initiation of 2205 duplex stainless steel passivation film

PurposeThis 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.Design/methodology/approachIn 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.FindingsWith 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.Originality/valueThe 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.

Study on the correlation between passive film and AC corrosion behavior of 2507 super duplex stainless steel in simulated marine environment

The correlation between passive film and AC corrosion behavior of 2507 super duplex stainless steel (SDSS) has been investigated in NaCl solution under various AC current densities using the polarization curve, EIS test, Mott-Schottky curve and with immersion test. Additionally, the corrosion mechanism of passive film under AC interference was studied by X-ray photoelectron spectroscopy (XPS) and atomic force microscope (AFM). The test results indicate that the roughness of the passive film increases and the composition as well as electronic properties change under AC interference. Moreover, AC interference can enhance the dissolution of passive film, resulting in a non-uniform destructive effect to the film. The passivity of stainless steel degrades and pitting sensitivity increases as the increase of iAC. When iAC is less than 100A/m2, the pit initiation sites mainly concentrate on the austenite phase and the boundary between ferrite and austenite phase. However, a great number of pits occur on the ferrite phase while iAC equals to 200A/m2.

Corrosion Rates of Stainless Steels in Renewable Biofuel Sources of Refined Rapeseed Oil, Waste Cooking Oil and Animal Waste Lard

The 1.4541 and the 1.4571 stainless steels and a carbon steel were subjected to immersion corrosion tests in stagnant and stirred biomass fuel sources such as rapeseed oil, waste cooking oil and animal waste lard as well as their emulsions with 5 and 50 wt.% aqueous citric acid solutions at a temperature of 80°C so as to model storage, handling and purification conditions. Passivation of carbon steel was facilitated by flow of the less acidic rapeseed and waste cooking oils and increased flux of oxygen. Carbon steel was sensitive for the higher concentration of proton donor species, acidity of the waste lard. Higher mass loss rates correlated with increased corrosion currents measured in citric acid solution by electrochemical methods. Flow of the biomasses and increased acid concentration of the emulsions were beneficial for the passivation of stainless steels. Although corrosion related mass loss, dissolution rate of the passive layers increased by flow and high acidity of the fluids, both the formation and compactness of passive layers are facilitated by the biomasses with higher concentration of oxygen donating species like water, alcohol and acids. Surface transformation of the passivating steels was reflected by decreasing electrochemical pseudo-capacity of the interfaces and increasing resistance of the passive layers derived from the results of Tafel and Stern methods as well as impedance results. Anti-correlation between mass loss results obtained by immersion in the biomasses and electrochemical data measured in dilute aqueous citric acid solution is explained by the varied compactness, resistance of the passive layers and exchange currents of the steel electrodes due to the orders of magnitude different activities of the hydrogen ion in the biomass mixtures and citric acid solution.

Revisiting the passivation of stainless steels and other passive CRAs

All that was said so far about passivity and passivation was indeed based on electrochemical prejudgments, and all based on unverified postulates. However, due the authors’ fame and for lack of anything better, the great many contradictions were carefully ignored. However, when resuming from raw experimental facts and the present general knowledge, it now appears that passivation always begins by the precipitation of a metallic hydroxide gel. Therefore, all the protectiveness mechanisms already known for porous corrosion layers apply, so that this outstanding protectiveness is indeed governed by the chemistry of transport processes throughout the entrapped water. For Al type passivation, the base metal ions only have deep and complete electronic shells, which precludes any electronic conductivity. Then protectiveness can only arise from gel thickening and densification. For Fe type passivation, an incomplete shell of superficial 3d electrons allows an early metallic or semimetallic conductivity in the gel skeleton, at the onset of the very first perfectly ordered inorganic polymers (- MII-O-MIII-O-)n. Then all depends on the acquisition, maintenance or loss of a sufficient electrical conductivity in this Faraday cage. But for both types of passive layers, all the known features can be explained by the chemistry of transport processes, with neither exception nor contradiction.

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.

Stainless Steel Passivation Using Electropolishing and Thermal Treatments

Tritium is highly reactive with many materials. It is adsorbed onto and absorbed through the surface of containment vessels subsequently modifying the contained gas composition by isotopic exchange and catalytic reactions with surface elements and adsorbed gas species. Savannah River Tritium Enterprise (SRTE) uses a proprietary surface treatment that is intended to render the surface inert. Unfortunately, this process has not proven to be sufficiently robust for containing tritium gas standards. SRTE has funded a project that will explore the effects of electropolishing and vacuum and oxidizing thermal treatments on surface passivation of stainless steel (SS). Herein, a statistically designed series of experiments will be discussed that will inform optimized parameters for acid composition, current density, and other electrochemical process variables for the passivation of SS. The surfaces were analyzed using Laser Induced Breakdown Spectroscopy (LIBS), Auger Electron Spectroscopy (AES), Atomic Force Microscopy (AFM), and Scanning Electron Microscopy (SEM). Novel techniques to characterize the passive layers are also being developed. In future experiments, gas sample bottles will be loaded with protium and deuterium to determine the relative exchange characteristics of the treated vessels. Previous work has indicated that if little protium ingrowth occurs or few contaminant species form, e.g., methane or ammonia, and little hydrogen exchange occurs in a protium and deuterium gas mixture the treatment is suitable for maintaining the tritium stability. This statement is not intended to imply that tritium, deuterium, protium mixes will not exchange, only that these results are useful as a screening tool prior to tritium exposure.

Characterizing biofilms for biofouling and microbial corrosion control in cooling water systems

Purpose The purpose of this paper is to study the metal-Microbe interaction playing a crucial role in microbiologically influenced corrosion (MIC) and biofouling of materials in cooling water systems. Treatment regimens should be planned based on this understanding. Design/methodology/approach Attempts were made in the past decades to characterize and understand biofilm formation on important power plant structural materials such as carbon steel (CS), stainless steel (SS) and titanium in fresh water and in seawater to achieve better control of biofouling and minimize MIC problems. Findings This report presents the results of detailed studies on tuberculation-formed CS because of the action of iron-oxidizing bacteria and the effects of algae- and bacteria-dominated biofilms on the passivity of SS. The preferential adhesion of different bacterial species on SS under the influence of inclusions and sensitization was studied in the context of preferential corrosion of SS weldments due to microbial action. Detailed characterization of biofilms formed on titanium (the likely condenser material for fast breeder reactors) after exposure for two years in Kalpakkam coastal waters revealed intense biofouling and biomineralization of manganese even in chlorinated seawater. Studies on the effectiveness of conventional fouling control strategies were also evaluated. Originality/value The detailed studies of different metal/biofilm/microbe interactions demonstrated the physiological diversity of microbes in the biofilms that were formed on different materials, coupling their cooperative metabolic activities with consequent corrosion behaviour. These interactions could enhance either anodic or cathodic reactions and exploit metallurgical features that enhance biofilm formation and/or the capacity of microbes to mutate and overcome mitigation measures.

Erosion-enhanced corrosion of stainless steel and carbon steel measured electrochemically under liquid and slurry impingement

The erosion-enhanced corrosion of 304 stainless steel and carbon steel under impingement by NaCl solution has been investigated. With increasing flow velocity, the open-circuit potential of carbon steel increases in the sand-free solution, while decreases in the sand-containing solution. The passive current density of stainless steel under impingement is close to that in quiescent condition in most cases, while increases by an order of magnitude at a flow velocity higher than the critical flow velocity. An ideal schematic has been used to explain the electrochemical results. The passivation of stainless steel under impingement is further analyzed by potentiostatic polarization.

Effect of Strain on Passivation of Stainless Steel in a Simulated Concrete Pore Solution

Passivation behavior of a deformed stainless steel in a simulated concrete pore solution was studied by means of open circuit potential (OCP), electrochemical impedance spectroscopy (EIS), and Mott-Schottky plots. The results show that with the increasing strain, the OCP and im- pedance of the steel decreased, whereas the concentration of oxygen vacancy in passive films in- creased. This result suggests that the passivation of the stainless steel is degraded by the increasing strain. In addition, the difference in passivation between the deformed samples would not be dimin- ished with the increasing immersion time.

Effects of Nitrogen on Passivity of Nickel-Free Stainless Steels by Electrochemical Impedance Spectroscopy Analysis

The effects of different nitrogen contents on the passivity of nickel-free stainless steels in 0.5 M sulfuric acid + 0.5 M sodium chloride solution were investigated by electrochemical impedance spectroscopy in the potential ranges of active dissolution and active-passive transition. A simplified reaction model containing adsorbed intermediates involved dissolution process, and passivation process was proposed to explain the impedance characteristics. Based on both equivalent circuit and mathematical model analysis, the effects of nitrogen on the passivity of stainless steels are discussed.

Molybdate‐doped copolymer coatings for corrosion prevention of stainless steel

ABSTRACTThe polypyrrole and polyaniline copolymer coating (PPy‐PAni) and PPy‐PAni doped with sodium molybdate copolymer coating ( ) were synthesized on stainless steel by cyclic voltammetry. The effect of molybdate on the passivation of stainless steel was investigated by linear sweep voltammetry in 0.2 mol L−1 of oxalic acid. The corrosion prevention performances of these copolymer coatings for stainless steel were investigated by linear sweep voltammetry, electrochemical impedance spectroscopy in 1 mol L−1 of sulfuric acid, and potentiodynamic polarization in 0.1 mol L−1 of hydrochloric acid. Copolymer coating doped with molybdate could accelerate the formation of the passive oxide film and have better corrosion prevention efficiencies than PPy‐PAni coating on stainless steel. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40602.

In Situ and Ex Situ Contact Resistance Measurements of Stainless Steel Bipolar Plates for PEM Fuel Cells

Passivation of stainless steel caused by the formation of an oxide layer on the surface is one of the main concerns when it comes to using stainless steel as bipolar plate material. Interfacial Contact Resistance (ICR) between the bipolar plate and the gas diffusion layer was measured both in situ and ex situ. A method for measuring ICR in situ was developed, and initial results showed that the ICR measured in situ is close to the ICR measured ex situ, for both non-coated and gold coated stainless steel bipolar plates. At a compaction pressure of 205.79 N cm-2, the in situ ICR was found to be close to 50 mΩ cm2 and the ex situ measurement performed on the same plate ex situ was found to be approximately 40 mΩ cm2. The in situ method for ICR measurements enables direct studies of the passivation processes at the bipolar plate interface, while the cell is in operation, under the actual fuel cell conditions.

Relevance of the cathodic process on the passivation of stainless steels – an approximation to the origin of the rouging phenomenon

AbstractUnwanted corrosive phenomena on stainless steel surfaces like rouging had been observed for years occurring at certain service conditions. Rouging consists in the formation of a colored surface film containing mainly iron on metallic surfaces in contact with high‐purity waters. In spite of numerous hypotheses and experimental examinations a clear explanation about the origin of rouging on stainless steels is currently still lacking. Because rouging occurs even at well passivated stainless steel surfaces the origin of this corrosive phenomenon should be related to the weakness of the stability of the passive film. In the present paper electrochemical noise measurements regarding the stability of the passive layer of alloy 904L (1.4539, X1NiCrMoCu25‐20‐5) in high‐purity water at 70 °C depending on the cathodic process are presented. In addition, the importance of the cathodic reaction on the passivation and stability of the passive layer is discussed.