Passive Film Research Articles

Nanosecond Laser Passivation and Corrosion Resistance Mechanism on the Surface of 2205 Duplex Stainless Steel

In addressing issues related to defects in laser quenching technologies, this study undertakes surface passivation treatment on 2205 duplex stainless steel. The investigation explores the impact of different laser parameters on the corrosion resistance of the passive film on the steel surface. The findings may provide theoretical references for the laser passivation treatment and corrosion resistance mechanism of steel surfaces.

Insights into the Influence of Tensile and Compressive Strain on the Microstructure and Corrosion Performance of 304 L Stainless Steel

The effects of tensile and compressive strain, originating from U-bent deformation, on the corrosion behavior of 304 L stainless steel were studied via analyses of the material’s microstructure and electrochemistry in a 3.5% NaCl solution. In contrast with the as-received 304 L steel with the largest grain size, the deformed 304 L material with a small grain size had the lowest number of Σ3 grain boundaries and an overall low fraction, with special low-Σ values (≤29). Moreover, the dislocation density increased to 1.13 × 1016/m2 and 1.4 × 1016/m2 for the tensile and compressive 304 L steel testing, respectively. The decrease in Epit and increase in ipit suggested that there was a decrease in anti-corrosion properties due to tensile and compressive deformation. This might be attributed to the higher plastic strain found in deformed 304 L steel, which can induce the rupture of passive film and have a harmful influence on corrosion resistance. In particular, the compressive 304 L steel with the highest content of deformed grains (42.12%) promoted the formation of microgalvanic cells, thereby facilitating the nucleation of pits. Then, these pits grew to a large size through grain shedding. Subsequently, massive chloride ions were generated during metal dissolution and diffused along grain boundaries, which promoted the initiation and propagation of intergranular corrosion cracks.

Prediction of Hydrogen Diffusion Behavior under the Influence of Defect Structures in Stainless Steel Passivation Film Based on Molecular Dynamics

Prediction of Hydrogen Diffusion Behavior under the Influence of Defect Structures in Stainless Steel Passivation Film Based on Molecular Dynamics

Microstructure, mechanical behavior, and cavitation erosion-corrosion resistance of the BCC/B2 strengthened FeNiCrMoAl-based multi-principal element alloys

The influence of disordered and ordered body-centered cubic (BCC-β and B2-β′) secondary phases on the mechanical properties and cavitation erosion-corrosion (CE-C) behavior of BCC/B2 strengthened FeNiCrMoAl-based multi-principal element alloy (MPEA) was systematically investigated. An increased β/β′ phases content enhanced the MPEAs’ strengths while maintaining good ductility. However, this increases also led to a higher proportion of loosely bound Al2O3 within the passivation film, resulting in a slight reduction in electrochemical corrosion performance. Remarkably, in a NaCl solution, the increased β/β′ phases significantly improved the MPEAs’ resistance to CE-C, attributed to the outstanding corrosion resistance and mechanical properties which could withstand elastic strain damage and plastic deformation.

Optimizing the corrosion resistance of additive manufacturing TC4 titanium alloy in proton exchange membrane water electrolysis anodic environment

Titanium alloys are commonly used as the bipolar plate material in proton exchange membrane water electrolysis (PEMWE). However, traditional machining methods are difficult to process titanium alloy parts, which further increases the cost of bipolar plates. The wire-arc directed energy deposition (WA-DED) additive manufacturing (AM) technology is low cost and high utilization of material. However, the undesirable microstructure always restricts the performance improvement. In this work, the electrochemical corrosion and passive characteristics of wrought TC4 and WA-DED AM TC4 alloys in the simulated PEMWE anode environment were investigated. The microstructure of AM TC4 alloy was optimized and the corrosion resistance was enhanced by heat treatment. The results indicate that the corrosion resistance of AM TC4 alloy is better than wrought TC4 alloy, and appropriate heat treatment can further improve the stability of passive film. Compared to wrought TC4, Ti −β phase fraction of AM TC4 decreased from 9.6 % to 1.3 %, and the heat treatment further reduced Ti −β phase fraction of AM TC4-850 and AM TC4-1050 alloys to 0.8 % and 0.1 %. The passive film thickness of wrought TC4, AM TC4, AM TC4-850, and AM TC4-1050 alloys calculated with the Power-Law model were 0.5 nm, 1.76 nm, 1.94 nm, and 2.02 nm, respectively. After heat treatment of 1050 °C, AM TC4-1050 alloy exhibited the best corrosion resistance, showing the lowest corrosion current density of 54 μA/cm2 and the lowest passive current density of 19.5 μA/cm2. Moreover, Ti oxide contributed most to the composition of passive film. In AM TC4-1050 alloy, the percentage of Ti oxides was 80.9 %, showing the best corrosion resistance.

Unraveling a Molecular Adhesion Mechanism at Complex Polymer-Metal Interfaces.

Controlling polymer-metal adhesion is critical in ensuring that materials can be cleanly separated during production processes without residue, which is crucial for various industrial applications. Accurately characterizing adhesion on industrial-grade surfaces is complex due to factors like surface roughness and actual contact area between surfaces and the polymer. In this study, we quantified the adhesive behavior of stainless-steel samples with varying surface treatments against a polymer using the surface forces apparatus (SFA) in reflection geometry, as well as X-ray photoelectron spectroscopy (XPS). We compared adhesive properties with the penetration depth of oxygen and the hydroxide-to-oxide ratio, which were modified by plasma and thermal treatments. Our results indicate that both treatment types enhance the deadhesive properties of the materials compared to native passive films, due to decreasing hydroxide functionality on the surface. Thermal treatment reduces adhesion further, due to an even lower hydroxide content, which reduces hydrogen bonding between the surface and polymer. Furthermore, we show that van der Waals forces, which depend on the density, have marginal to no influence on the adhesive behavior. This study not only advances our understanding of the factors influencing polymer-metal adhesion but also demonstrates the application of the SFA in reflection geometry for characterizing industrially relevant rough surfaces.

Unveiling the effect of bovine serum albumin on the corrosion resistance of high nitrogen stainless steel for cardiac stents

Herein, the effect of bovine serum albumin (BSA) on the corrosion resistance of high nitrogen stainless steel (HNS) is systematically investigated based on experimental characterizations and first-principle calculations. Electrochemical measurements firstly prove that the anodic dissolution rate of HNS has significantly increased due to BSA adsorption and the potential deterioration of the passive film. By subsequent morphology and composition characterizations, it is demonstrated that BSA forms a 1.9 μm porous adsorption layer on HNS surface via the peptide bond mostly in -helix and -turn structure. Furthermore, Mott-Schottky tests confirm that the carrier (cation vacancy) density in the passive film has dramatically risen from 6.29×1021 cm-3 to 1.97×1022 cm-3 after BSA adsorption, which could be ascribed to the detachment of Cr atom from its original lattice due to the preference interaction between BSA molecule and Cr atom. Most importantly, such an increased defects will further promote the dissolution process of both the passive film and HNS matrix according to point defect model (PDM), which will definitely undermine the protective ability of the passive film and eventually result in the declined corrosion resistance of HNS in BSA-contained solution.

Metastable Pitting Corrosion Behavior of the Incoloy 825 Liner of Metallurgically Clad Pipe in Simulated Oilfield Produced Water

This study investigates the metastable pitting corrosion behavior and passive film characteristics of metallurgically clad pipe (MCP) 825 within simulated oilfield produced water. Electrochemical testing and microstructural examination were employed to assess the corrosion behavior. The results revealed a narrowing of the passivation region and an increased frequency of metastable pitting nucleation. These phenomena are attributed to the enlarged grain size and the proliferation of precipitate phases within the MCP 825. X-ray photoelectron spectroscopy analysis unveiled a decreased fraction of Cr3+ and Fe3+ ox in the passive film. Additionally, an elevated concentration of vacancies and a rapid vacancy diffusion rate were observed, leading to diminished defect performance as indicated by Mott-Schottky (M-S) and electrochemical impedance spectroscopy (EIS) results.

Research on the multi environmental corrosion characteristics and mechanism of B4C doped Fe–Cr–Ni composite coating produced by laser cladding

Different Fe–Cr–Ni composite coatings doped with B4C were produced on the surface of Cr12MoV steel by laser cladding. Special attention was paid to the effects of B4C content on the phase composition, microstructure, and corrosion resistance of the cladded layers. The results indicated that the Fe–Cr–Ni composite coating was primarily composed of α-(Fe, Cr) and γ-(Ni–Cr–Fe) solid-solution phases, as well as Fe2B, M7C3, Fe3Si and M23C6 phases. Once the B4C content increased to 10 wt%, the microstructure of the cladding layer became coarse and exhibited the prominent carbide agglomeration. The composite coatings with different B4C contents exhibited superior corrosion resistance compared to the pure substrate in both 3.5 wt% NaCl and 1 mol/L HCl solutions. Furthermore, as the B4C content increased, the corrosion resistance of the coating initially increased and then declined. In particular, the Fe–Cr–Ni composite coating with an 8 wt% B4C content experienced the pronounced passivation in the corrosive media and possessed the optimal corrosion resistance due to the synergistic effect of the passive film and carbide barrier layer.

Design and fabrication of multiphase TiVCrZrW films with superior wear resistance and corrosion resistance

High entropy alloys (HEAs) have the potential to overcome the conflict between hardness and toughness by incorporating dual-phase or multiphase structures. Under unbalanced magnetron sputtering, HEA films with large atomic size differences tend to form non-monophasic structures. In this study, based on a phase diagram calculation simulation, a multiphase TiVCrZrW film with deposition temperature-induced phase separation was successfully designed. Interestingly, the TiVCrZrW film deposited at 600 °C exhibited a multiphase structure including a double body-centered cubic (BCC) phase and Laves phase by spinodal decomposition, realizing a balance between hardness and toughness. The tribological experiments showed that the multiphase TiVCrZrW film provided superior wear resistance, with a minimum wear rate of 2.63 × 10−6 mm3/(N·m). The electrochemical experiment demonstrated the outstanding corrosion resistance of the multiphase TiVCrZrW film, and the corrosive solution was effectively inhibited by the ZrO2 and Cr2O3 oxides passive film formed on the surface. According to the results of this study, TiVCrZrW protective films have a wide range of potential applications in various fields of marine engineering.

Corrosion resistance and wear behavior of CoCrFeNiMn@Gr high entropy alloy-based composite coatings prepared by laser cladding

In this study, we utilize laser cladding to apply a CoCrFeNiMn HEA with 2 wt.% few-layer graphene (Gr) coating onto the surface of Q235B mild steel. Alcohol stirring method was used for HEA and Gr preparation of composite powder. Raman spectroscopy and energy dispersion spectroscope (EDS) indicate the successful mixing of HEA and Gr powders, with Gr adhering to the surface of the HEA powder in a lamellar structure. The X-ray diffraction (XRD), scanning electron microscope (SEM), EDS, and Electron backscatter diffraction (EBSD) analyses revealed that grain refinement and the formation of fine carbide-hard phases in the HEA/Gr coating improve microhardness and wear resistance. The average Schmidt factors of the coating decreased from 0.47 to 0.45 with the addition of Gr, indicating enhanced resistance to plastic deformation and anisotropy. Nanoindentation experiments demonstrated that the HEA/Gr coatings exhibit superior resistance to plastic deformation, effectively enhancing the coating’s durability against spalling under stress and wear conditions. The microhardness of the HEA/Gr coating increased by 99.25%, and the wear rate decreased by 86.31% compared to the HEA coating alone. The open circuit potential (OCP), linear polarization curve, Tafel curves, electrochemical impedance spectroscopy (EIS), and Mott-Schottky tests all indicated that the HEA/Gr coating possesses superior corrosion resistance. X-ray Photoelectron Spectroscopy (XPS) results suggest that the passivation film of the HEA/Gr coating, which contains more oxides and less hydroxide, is more protective and denser, thereby slowing the corrosion rate.

Pitting corrosion resistance of tempered N08825 alloy in the inner layer of bimetallic composite pipe

Pitting corrosion resistance of N08825 alloy in the inner layer of bimetallic composite pipe SA210A/N08825 tempered at 570∼720 ℃ was investigated in NH4Cl solution by scanning electron microscopy (SEM), X-ray diffraction (XRD), and electrochemical measurement techniques. The M23C6 precipitates, observed at the grain boundaries of inner layer alloy 825, exhibit a temperature-dependent behavior during tempering at 570∼720 ℃. The quantity of M23C6 precipitates and the pitting corrosion resistance change with the tempering temperature. When the tempering temperature increases from 570 to 660 ℃, the quantity of M23C6 precipitates increases, with the pitting potential (Ep) decreasing from about 499 ± 8.6 to 354 ± 6.7 mVSCE, the passive current density (ip) increases from about 1.9 ± 0.2 to 2.45 ± 0.3 μA cm-2, and the average number of pits on the specimen surface rises from 3 to 7. Conversely, when the tempering temperature increases from 660 to 720 ℃, the quantity of M23C6 precipitates decreases, leading to the Ep increases from about 354 ± 6.7 to 394 ± 14.6 mVSCE, the ip decreases from about 2.45 ± 0.3 to 2.34 ± 0.4 μA cm-2, and the average number of pits on the specimen surface decreases from 7 to 6. There is a strong relationship between the M23C6 precipitates and the pitting corrosion resistance. As the quantity of M23C6 precipitates increases, it results in the expansion of Cr-depleted zones on the specimen surface, the rise of passive film defects, and a subsequent reduction in the pitting corrosion resistance of inner layer alloy 825.

A significant improvement in corrosion resistance and biocompatibility in ZrNbTiCrCu high-entropy films induced by the precipitation of Cu

Utilizing nanotechnology and composites to create a protective film on titanium alloy is an effective means of achieving the desired high performance. Self-assembly of nanocomposite structures offers a promising route to forming high entropy alloy films (HEAFs), but controlled preparation remains challenging. This work used magnetron sputtering through adjusting preparation parameters to prepare ZrNbTiCrCu HEAFs, achieving a significant improvement in corrosion resistance and biocompatibility induced by the precipitation of Cu. According to the electrochemical corrosion test, without obvious corrosion pits on the surface of S2 after corrosion, a passivation film composed of bimetallic oxide CuCrO2 formed on the film surface, indicating that ZrNbTiCrCu HEAFs have remarkable corrosion resistance performance. In the cytocompatibility experiment, the cell viability of HEAFs reached over 95 % due to the precipitation of Cu, suggesting their excellent biocompatibility. In addition, ZrNbTiCrCu HEAFs exhibit outstanding antibacterial ability, especially when the sputtering current is 0.6 A, and the in vitro antibacterial rate of the sample against Escherichia coli is close to 99 %.

Corrosion and wear mechanisms of rare earth (Gd, Sc, Y)-doped Zr-based amorphous alloys

Rare-earth elements have been utilized in the design and development of new amorphous alloys to improve the corrosion and wear resistance of Zr-based amorphous alloys. In this study, a rare-earth doped Zr-based amorphous alloy (Zr-BMG(RE)) was prepared by the copper mold casting method, which was investigated by corrosion and wear experiments. The results show that Zr-BMG(RE) has a completely amorphous structure, and the doping of rare earths Gd and Y raises the crystallization transition temperature of the amorphous. The addition of rare earth elements Gd and Sc increases the microhardness of Zr-based amorphous alloys, while rare earth element Y causes a slight decrease in microhardness. Gd and Sc will make Zr-based amorphous materials corrosion current density increases, the material pitting and localized corrosion, acid corrosion resistance is reduced. Y doping improves the self-corrosion potential of Zr-based amorphous alloys, reduces the corrosion current density, the surface passivation film is the densest, and the degree of charge transfer on the metal surface is the most difficult, Zr-BMG(Y) has a better corrosion resistance compared with other alloy materials. Zr-BMG(Gd) has the smallest friction rate (1.72×10-7mm3N-1mm-1), and the wear rates of the rare earth doped Zr-based amorphous alloys are all smaller than that of Zr-BMG, and the main loss mechanism of Zr-based amorphous alloys is the interaction of adhesive wear, abrasive wear, oxidative wear and fatigue wear. The mechanism of corrosion and wear resistance of rare earth to Zr-based amorphous alloys is discussed, which provides a new idea for the design of amorphous alloys.

A novel fine-grained TiZrCu alloy tailored for marine environment with high microbial corrosion-resistance

Titanium alloys, usually known as non-corrodible material, are susceptible to microbiologically influenced corrosion (MIC) in marine environment. While titanium-zirconium (TiZr) alloys have been extensively studied in medical applications, the influence of microorganisms, especially marine microorganisms, on their corrosion behavior has not been explored. In this work, a TiZrCu alloy with a combination of excellent mechanical, anti-corrosion, and antibacterial properties was developed by optimizing the Cu content and grain refinement. Its MIC and antibacterial mechanisms against Pseudomonas aeruginosa, a representative marine microorganism, were systematically investigated. 5.5 wt% was determined as the optimal copper content. The fine-grained Ti-15Zr-5.5Cu (TZC-5.5FG) alloy maintained high MIC resistance, exhibiting a corrosion current of 5.7 ± 0.1 nA/cm2 and an antibacterial rate of 91.8 % against P. aeruginosa. The mechanism of improved corrosion resistance was attributed to the denser passive film with high TiO2 content and the lower surface potential difference ΔE. The release of Cu2+ ions, ΔE, and the generation of ROS are three major factors that contribute to the antibacterial performance of TiZrCu alloys. Compared to other available marine metals, TZC-5.5FG alloy exhibited superior comprehensive performance, including excellent mechanical properties and anti-MIC capacity, which make it a promising material for load-bearing applications in marine environment.

Effect of neodymium on microstructure, mechanical properties, and corrosion behavior of Mg-2Si-xNd alloys fabricated by powder metallurgy

In the present work, the effects of neodymium (Nd) on microstructure, mechanical performance, and corrosion behavior of powder metallurgy Mg-2Si-xNd (x = 0.05 wt%, 0.15 wt%, and 0.20 wt%) alloys were investigated. Microstructures were examined by optical and scanning electron microscopes combined with an energy-dispersive spectrometer. Hardness and compressive tests were used to study the mechanical properties of alloys. Potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), Mott-Schottky analysis, and the hydrogen evolution test were applied to characterize the corrosion behavior of alloys in Hanks’ solution. The microstructure of Mg-2Si-xNd alloys mainly consists of α-Mg matrix, Mg2Si, and MgNd phases. The increase in Nd content tends to decrease the aspect ratio of α-Mg grains, which leads to the enhancement of the ultimate-compressive strengths and hardness of the alloys. Potentiodynamic polarization shows that increasing Nd content leads to a lower corrosion current density in the Mg-2Si-xNd alloys. The EIS results confirm that a higher addition of Nd suppresses the dissolution kinetics of the alloys due to the increasing charge transfer resistance. Mott-Schottky analysis reveals the formation of an n-type semiconductive passive film on the alloy surfaces, where the interstitial and oxygen vacancies predominate over the metal vacancies. The X-ray photoelectron spectroscopy (XPS) reveals that a mixture of Mg(OH)2, MgO, MgCO3, and Nd2O3 has formed as the corrosion products on the Mg-2Si-xNd alloy surfaces after a longer immersion time in Hanks’ solution.

Fabrication of Mo-encapsulated stainless steel by powder metallurgy and assessment of localized corrosion resistance

As a source of corrosion inhibitors, 2.5% Mo powder was mixed with Type 304L stainless steel powder and spark-plasma sintered to a fabricate Mo-encapsulated Type 304L stainless steel. The Mo particles formed a core/shell structure. The localized corrosion resistance of the fabricated Mo-encapsulated Type 304L stainless steel was compared with those of spark-plasma-sintered Type 304L and Type 316L stainless steels. Potentiodynamic polarization in 0.1 M NaCl suggested that the Mo cores could release molybdate, which acts as an inhibitor. However, the shells did not dissolve, preventing the Mo-enriched particles from acting as pit initiation sites. Similarly, the surface of the Mo core dissolved during dip-and-dry cycles using 0.1 M NaCl, but the shell was less prone to dissolution. Although the fabricated Mo-encapsulated stainless steel did not contain Mo as a solid solution, its rust resistance was equivalent to that of spark-plasma-sintered Type 316L stainless steel. In potentiodynamic polarization, the initiation potential for localized corrosion of the Mo-encapsulated Type 304L stainless steel was remarkably higher than those of the sintered Type 304L and Type 316L stainless steels. The corrosion inhibition mechanism of the Mo-encapsulated Type 304L stainless steel was discussed from three viewpoints: (1) passive film modification on the steel matrix, (2) cathodic protection of the steel matrix by the Mo core dissolution, and (3) corrosion inhibition by molybdate dissolved from the Mo-enriched particles, and the last one appeared to be the most likely.

Enhancing corrosion resistance of Al alloy sheets with potential gradient by arc-sprayed Zn coatings

To improve the corrosion resistance and wide the application of Al alloy sheet in the engineering production, a corrosion potential gradient along the thickness of the Al alloy sheet was fabricated using the sprayed Zn layer. The process of arc spraying was employed to obtain the Zn coating with optimizing the parameters. Electrochemical testing was conducted on the surface of Al alloy sprayed with Zn layers at different depths. As the depth in the thickness direction increases, the content of Zn alloy elements gradually decreases and the potential gradually increases. This exhibits a gradual decrease in corrosion tendency. The results of electrochemical impedance spectra (EIS) revealed the existence of pitting corrosion on the surface of the Al alloy. This even extended to the underlying substrate material. In contrast, the Zn coating, when exposed to a corrosive environment, demonstrated the beneficial cathodic effect as a sacrificial anode and the protective function of a passivating film, thus mitigating corrosion. The gradual increase in charge transfer resistance in the impedance spectrum suggested that the corrosion resistance of the sample is increasingly improved. Therefore, it exhibited remarkable resistance to corrosion. Additionally, the SEM surface morphology and XRD pattern were utilized to further explain the corrosion mechanism of the arc-sprayed Zn coating. The Zn coating can provide sacrificial protection to the Al layer due to its higher negative potential and localized corrosion reactivity. This is attributed to the micro-galvanic couples formed between the Zn and Al layer, thus increasing the corrosion resistance of the sheets.

Green Film Forming Technology Based on Polydopamine Galvanized

At present, the mainstream passivation agent is chromate passivation agent, but it has the disadvantages of high toxicity and high price, so this project seeks to find a safer, cheap and green chromium-free passivation agent. Because dopamine and chitosan derivatives have certain corrosion inhibition properties on metals in acidic media, these polymer corrosion inhibitors can achieve high corrosion inhibition rates at high concentrations. Therefore, in this experiment, dopamine was added on the basis of sodium silicate, and the sample was passivated to explore the potential enhancement effect of dopamine on the passivated film performance. After the sample was treated, the impedance value could be fitted by electrochemical impedance spectroscopy and Zsimpwin software, and then the Tafel polarization curve was drawn. It was found that the addition of dopamine significantly improved the corrosion resistance of the passivated film. By promoting the positive shift of self-corrosion potential and greatly reducing the self-corrosion current density, the protective barrier effect of passivation film on metal matrix is effectively enhanced. Finally, the experiment successfully proved that the corrosion resistance of the passivation film after adding dopamine was better

Quantification of Interfacial Voids Using Positron Annihilation Spectroscopy for Mechanism Study on SiCN Bonding and SiN Bonding

Abstract Hybrid bonding for 3D integration requires reliable direct bonding interface of dielectrics. Lately, the spotlight has focused on SiCN/SiCN bonding considering its superior bonding performance by the dangling bonds-facilitated nanovoid closure mechanisms, but it is reported to be sensitive to reactive species especially under the high temperatures. Recent work proposed SiN/SiO2 asymmetric bonding showing a void-free bonding interface and bond energy higher than 2.5 J/m2 as a promising candidate for direct bonding applications. Interestingly, we observed opposite bonding behaviors between SiCN and SiN in corresponding symmetric bonding pair and asymmetric bonding pair (with SiO2). Thus, a comprehensive fundamental understanding on the bonding of different dielectrics is needed to guide the specifications of the bonding layer for enabling a void-free and highly reliable bonding interface. In this study, we systematically quantified the nanovoids in the bonding interface of SiCN/SiCN, SiCN/SiO2, and SiN/SiO2 through positron annihilation spectroscopy and simulation, dangling bond formation by electron spin resonance, and the film passivation property by quasi-steady-state photoconductance. By correlating the film properties and bonding performance, the model of SiCN bonding is extended towards its SiCN/SiO2 asymmetric bonding, and a new model of the nanovoid closure mechanism in SiN bonding is first-time proposed.