Corrosion Resistance Of Films Research Articles

Influence of the activation time of magnesium surfaces on the concentration of active hydroxyl groups and corrosion resistance

Magnesium alloys have been extensively studied as degradable biomaterials for clinical applications due to their biocompatibility and mechanical properties. However, their poor corrosion resistance can lead to issues such as osteolysis and the release of gaseous hydrogen. This study investigated the influence of the activation time of magnesium surfaces in a sodium hydroxide (NaOH) solution on the concentration of active hydroxyl groups and corrosion resistance. The results indicated that immersion time significantly influences the formation of a corrosion-resistant film and the distribution of surface hydroxyl groups. Specifically, specimens treated for 7.5 h exhibited the highest concentration of hydroxyl groups and the most uniform oxide film distribution. Electrochemical tests demonstrated capacitive behavior and passive surface formation for all evaluated times, with the 7.5-h immersion in NaOH yielding superior corrosion resistance, lower current density, and a more efficient and thicker protective film. SEM and EDS analyses confirmed increased formation of Mg(OH)₂ for samples treated for 5 and 7.5 h, while a 10-h treatment resulted in a brittle, porous layer prone to degradation. Statistical analysis using ANOVA and Fisher's LSD test corroborated these findings. The optimal 7.5-h alkali treatment enhanced magnesium's corrosion resistance and surface properties, making it a promising candidate for orthopedic implants. However, further studies are necessary to assess biocompatibility and physiological responses before clinical implementation.

Effect of Temperature on Passive Film Characteristics of LPBF (Laser Powder-Bed Fusion) Processing on UNS-S31603.

The effect of temperature on the localized corrosion resistance and passive film characteristics of laser powder-bed fusion (LPBF) 316L (UNS S31603) was studied in a buffered 3.5 wt% NaCl solution at 25, 50, and 75 °C. DC techniques such as cyclic potentiodynamic polarization showed lower passive current densities, high breakdown potentials, and a higher resistance to initial breakdown compared with wrought 316L samples at all temperatures. However, LPBF 316L was more susceptible to metastable pitting at potentials before film breakdown and higher damage accumulation post film breakdown. AC techniques, such as Mott-Schottky analysis and electrochemical impedance spectroscopy, showed that the formed passive film was more robust on the LPBF 316L samples at all temperatures, accounting for the higher initial resistance to pitting. However, with increasing temperatures, the film formed had an increasing concentration of defect density. Passive compositions at the various test temperatures studied using X-ray photoelectron spectroscopy (XPS) showed that the LPBF samples showed higher amounts of Cr and Fe oxides and hydroxides compared with the wrought samples, which made the passive films on the LPBF samples more compact and protective. Investigation of the pits formed on the LPBF showed the preferential regions of attack were the melt-pool boundaries and cell interiors due to their being depleted of Cr and Mo when compared with the boundaries and matrix.

Step-by-step in-situ preparation of magnesium-aluminum layered double hydroxide film to improve the corrosion resistance of AZ31 magnesium alloy

In this study, a hydrothermal method was employed to cultivate Mg(OH)2 precursor layers on the surface of AZ31 magnesium alloy samples. Subsequently, Mg-Al LDHs films were successfully synthesized through an in-situ growth approach. The phase composition of the films were analyzed using X-ray diffraction and infrared spectroscopy. The growth process and surface morphology of the films at the microstructure level were examined and interpreted using scanning electron microscopy and EDS. The corrosion resistance of the films was assessed through potentiodynamic polarization curves, electrochemical impedance spectroscopy, and hydrogen evolution tests. The findings indicate that the Mg(OH)2 precursor effectively mitigates defects in the Mg-Al LDHs films and improves the LDHs microstructure. Moreover, the precursor synthesized at a pH range of 10–12 better enhances the corrosion resistance of the Mg-Al LDHs film.

Effect of V2O7 4− anion intercalation on the microstructure and corrosion resistance of MgAl Layered Double Hydroxides films on LA43M Mg-Li alloy

ABSTRACT To improve the corrosion resistance of LA43M alloy, MgAl-NO3 −-Layered Double Hydroxides (LDH) was prepared on the surface of the alloy by an in situ hydrothermal method, and uniform and dense MgAl-V2O7 4−-LDH films were successfully obtained by ion-exchange over different times. SEM, XRD, EDS, electrochemical polarisation, EIS and hydrogen evolution experiments were conducted to analyse microstructure and corrosion resistance of these films. The results verified that with increase of the ion-exchange reaction time, the nanosheets of the MgAl-V2O7 4−-LDH film are larger in size, uniformly distributed, and slightly increased in thickness. The surface of the modified MgAl-V2O7 4−-LDH film grown for 4 h on the surface had a staggered and tilted manner, and the gaps between the nanosheets were small, making it more effective in blocking the corrosive medium. The MgAl-NO3 −-LDH film modified by V2O7 4− anion intercalation can further improve the corrosion resistance of the LA43M alloy.

Structure and performance of N-doped amorphous carbon films (a-C: N) on stainless steel surfaces for bipolar plates in proton exchange membrane fuel cells

Stainless steel bipolar plates (BPPs) are anticipated to supersede traditional graphite BPPs in proton exchange membrane fuel cells (PEMFCs) owing to their superior machinability, enhanced mechanical strength, and cost-effectiveness. Nevertheless, stainless steel BPPs are susceptible to corrosion and dissolution in acidic environments over extended periods, leading to the formation of a passivation film that diminishes conductivity. In this study, amorphous carbon (a-C) films with varying N doping contents were deposited onto 304L stainless steel foil using the cathodic arc ion plating technique. This was achieved by manipulating the N2 flow rate. The research investigated the impact of N doping on the microstructure, corrosion resistance, interfacial contact resistance (ICR), and hydrophobicity of the a-C films on stainless steel surfaces. The findings reveal that the various a-C films significantly enhance the performance of 304L stainless steel under simulated PEMFCs operating conditions. While N-doped a-C (a-C: N) films are advantageous for reducing ICR, incorporating N results in a decrease in C-sp3 content and density, ultimately leading to a decrease in the corrosion resistance of films. Additionally, the hydrophobicity of the a-C films diminishes with increasing N content. Consequently, N doping is not conducive to improving the overall performance of a-C films on the surface of 304L stainless steel bipolar plates under simulated PEMFCs operating conditions.

Corrosion characteristic of vitallium 2000 CoCrMo casting alloy in fluoride containing artificial saliva

In order to reveal the effect of fluoride ions (F−) on the passive film corrosion resistance and composition of CoCrMo dental prosthesis. The passivity of casting Vitallium 2000 CoCrMo series alloy was systematically studied by adopting electrochemical and surface techniques. The results show that F− have a certain effect on the passive film corrosion resistance of casting CoCrMo in oral environment, and the increase of F− concentration weakens the passive film corrosion resistance. With the increase of F− concentration, the open circuit potential moves negatively, the corrosion current density increases, the polarization resistance decreases, and the defect density in the passive film increases. With the extension of immersion time, the corrosion resistance of alloy will be enhanced and shows: AS > AS + 0.5 wt% NaF > AS + 1 wt% NaF. The addition of F− can decrease Co, Cr and Mo peaks sharply and promote the dissolution of the passive film. The result of present study could regulate and guide the application dose of oral fluorine-containing products.

Functional modification of TC4 by Cu-containing titanium dioxide films

To improve the biological fouling and corrosion resistance of Ti6Al4V (TC4) in marine environments, copper-containing titanium dioxide (TiO2(Cu)) films were prepared by magnetron sputtering TiO2(Cu) powder targets. The morphologies of the films showed that they became rough and coarse from 1.6 nm of the TiO2 film to approximately 9 nm of the TiO2(Cu) films, which might be owing to the increase in the deposition rates from 1.33 to 2.08 nm/min. No diffraction orientations of the TiO2 and Cu phases were found compared to those of the TiO2(Cu) powder. Ti, O, and Cu were detected using X-ray photoelectron spectroscopy to confirm the composition of the films. The ratio of Cu2+ increased as the Cu content of the films increased, whereas that of Cu/Cu + scarcely changed. The TiO2 and TiO2(Cu) films exhibited photocatalytic effects and their photocatalytic intensities decreased as the Cu content increased. Hydrophobicity was enhanced by the addition of Cu to the film. The antibiological fouling effect of the TiO2(Cu) films remained unchanged as the Cu/Ti ratio varied. Compared with those of TC4, the corrosion current densities of the TiO2(Cu) films decreased by one order of magnitude and the corrosion potentials increased by 350 mV in artificial seawater, indicating that the corrosion resistance of TiO2(Cu)/TC4 was improved. Importantly, Cu was in abundance in the films for both antibiological and corrosion resistance functions owing to the saturated ratio of Cu/Cu+ irrespective of the Cu/Ti ratio in the films.

Corrosion resistance and ion exchange properties of montmorillonite film on AZ31 in SBF solution

Montmorillonite (MMT) film was prepared on the surface of alkali-heat treated Mg alloys by one-step hydrothermal method. The structure and composition of MMT film were characterized using scanning electron microscopy, energy dispersive spectroscopy, X-ray diffractometry, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The corrosion resistance of MMT film in simulated body fluid (SBF) was investigated using electrochemical tests and immersion experiments. The experimental results showed that with the extension of hydrothermal time, the corrosion resistance of film increased and then decreased. With the increase of MMT powder mass fraction in precursor solution, the corrosion resistance of films also increased and then weakened. The best performance of MMT films was obtained at hydrothermal time of 12 h and MMT powder mass fraction of 2 wt%, with an impedance value of 9.77×106 Ω·cm2, which is an improvement of four orders of magnitude compared to substrate, and the efficiency of corrosion protection was up to 100%. The ion exchange properties, barrier effect and inertness characteristics of MMT provide excellent corrosion protection for magnesium substrates. This study provides a new coating strategy for the preparation of biodegradable magnesium alloys with excellent corrosion resistance and biocompatibility for use as biomedical materials.

Modification of bis-silane film with cerium salt for improved corrosion protection of sintered NdFeB

In this paper, a corrosion-resistant film (the cerium/bis-silane composite film) was fabricated on sintered NdFeB substrate by a simple and effective one-step film preparation method. The method uses an electrochemically assisted deposition technology to create superhydrophobic micro/nanostructures, during which the electrochemical oxidation of rare earth ions produces oxides and hydroxides to be deposited in the film layer. The experiment results show that the cerium/bis-silane composite film exhibited superhydrophobicity (hydrophobicity angle of 152°) and high corrosion resistance. The Icorr values for the cerium/bis-silane composite film is 1.81 × 10−6 A/cm2 with an inhibition efficiency of 74.6%. By characterising the morphology of its surface and cross-section, it can be observed that the cerium/bis-silane composite film is thicker and more uniform than the bis-silane (Ethyl orthosilicate (TEOS) + Dodecyltrimethoxysilane (DTMS)) film. Additionally, due to its superhydrophobic surface, 3D network structure, and alkaline passive layer, the cerium/bis-silane composite film was highly effective in preventing the infiltration and diffusion of corrosive ions. Furthermore, the cerium/bis-silane composite film has very little influence on the magnetic properties of the sintered NdFeB, being a hopeful candidate for the new environment-friendly protective coatings to be used in the NdFeB and related industries.

Rosmarinus officinalis l. Oil as an Eco-Friendly corrosion inhibitor for mild steel in acidic Solution: Experimental and computational studies

In this research, Rosmarinus officinalis L. (ROL) essential oil extracted from the plant was initially introduced as a green anti-corrosion agent for mild steel (MS) in a 1 M HCl solution. The components of the extract were identified using gas chromatography-mass spectrometry (GC–MS) and UV–Vis method. Gravimetric and electrochemical techniques (EIS and PDP) demonstrated that ROL inhibited steel corrosion by 90 % at a concentration of 1.5 g/l. The PDP experiment indicated that ROL essential oil acted as a mixed-type inhibitor with a cathodic predominance. The morphological and elemental characteristics of the metal surface were examined using SEM and EDX, revealing the formation of a corrosion-resistant film on the metal surface. The inhibited corrosive solutions were characterised before and after immersing MS using UV–visible spectrophotometry, indicating the possibility of iron-ROL complex formation. Finally, theoretical calculations using DFT, MC, and MD simulations were conducted and correlated with experimental results.

Corrosion resistance and mechanism of high‐entropy alloys: A review

AbstractEnvironmental corrosion inevitably occurs during the use of alloys, making their corrosion resistance a special requirement for their application under specific conditions. The environmental corrosion behavior of alloys, seawater corrosion behavior, corrosion resistance, and microstructure of high‐entropy alloys (HEAs) have been prominent research topics over the past decade, all of which warrant further investigation. The corrosion resistance and passivation film strength of HEAs could be enhanced by improving their microstructure with appropriate adjustments of their elemental composition and content. In this review, the research status and corrosion mechanism of HEAs in seawater solutions with NaCl as the main component were examined. Moreover, the correlation between the microstructure, elemental composition, and corrosion resistance of HEAs was revealed.

Corrosion Resistance, Composition, and Stratification of Passive Films: Ni-22Cr and Ni-22Cr-6Mo Alloys Passivated and Exposure Aged in Acidic Chloride Solutions

Ni-Cr based super-alloys have exceptional corrosion resistance, which is further improved with Mo alloying. The correlation between passive layer performance and composition was studied to gain a deeper mechanistic understanding of the role of Mo by comparing the behavior of Ni-22Cr to Ni-22Cr-6Mo (wt%) alloys. The passive layers were formed using galvanostatic holds to create fast and slow growth conditions using high and low current densities. A potentiostatic hold was added to initiate exposure aging. The passive film was characterized using electrochemical impedance spectroscopy (EIS), linear sweep voltammetry (LSV), atomic emission spectro-electrochemistry (AESEC), and X-ray photoelectron spectroscopy (XPS). Combined electrochemical and XPS characterization offered insight in cation concentrations and stratification, bonding states (oxide, hydroxide), and their modulation as a function of electrochemical conditions and performance. Most importantly: (i) Mo addition enhanced Cr(III) bound in oxide, (ii) fast growth conditions resulted in less corrosion resistant films, and (iii) exposure aging increased Cr-enrichment and reduced stratification of Mo-cations. The correlation between passive film performance and Cr, Ni, and Mo oxidation states, bonding, oxide-hydroxide contributions, and stratification is discussed. Generally accepted correlations, such as Cr-cation concentration and performance of the passive layer, have to be reexamined in order to account for the complex chemical make-up of the passive layer.

Corrosion behavior of AlCoCrFeNi2.1 high entropy alloy in a simulated oilfield produced fluid environment compared to 2205 duplex stainless steel

In this study, we investigated the corrosion resistance and passive film characteristics of AlCoCrFeNi2.1 high entropy alloy (HEA) and 2205 duplex stainless steel (DSS) when exposed to a simulated oilfield produced fluid. Our findings reveal that AlCoCrFeNi2.1 HEA exhibits a nobler self-corrosion potential (−340 mVSHE) and a lower self-corrosion current density (3.6 μA/cm2), in comparison to 2205 DSS, exhibiting better overall corrosion resistance, albeit with a narrower stable passivation interval. Long-term immersion tests establish that AlCoCrFeNi2.1 HEA primarily experiences overall corrosion, while 2205 DSS mainly undergoes localized corrosion, notably characterized by pitting corrosion. The predominant elements in the passive film on AlCoCrFeNi2.1 HEA are Al (13.4 at%), supplemented by varying amounts of Fe (2.4 at%), Cr (4.8 at%), Ni (2.2 at%), and Co (1.3 at%). In contrast, the passive film formed on 2205 DSS consists solely of Fe (7.9 at%) and Cr (5.0 at%). The absence of the corrosion-resistant elements Mo and Ni in the passive film of 2205 DSS may account for its inadequate corrosion resistance.

Electrodeposition-hydrothermal synthesis of inhibitor anion-intercalated layered double hydroxide films for corrosion resistance on steel substrates

The in-situ growth of layered double hydroxide (LDH) film on steel substrates holds huge potential for corrosion protection in reinforced concrete. However, because steel will passivate in alkaline environments, almost only CO32−-LDH films can be grown in situ on carbon steel surfaces at present, limiting the ability of LDH to release inhibitory anions. In this study, we proposed a novel electrodeposition-hydrothermal method to grow Mg/Al-NO3−-LDH films in situ on Q235 steel substrates. Subsequently, CO32−, PO43−, and V2O74− anion-intercalated LDH films were successfully prepared through anion exchange to enhance their functional applications. All LDH films were dense, uniform, and exhibited good adhesion to the substrate, with a thickness of approximately 20 μm. The electrochemical results demonstrated a significant improvement in the corrosion resistance of the steel containing LDH films. Specifically, the LDH films with intercalated inhibitory PO43− and V2O74− anions exhibited corrosion protection efficiencies exceeding 97.37 % in 3.5 wt% NaCl solution and 99.99 % in simulated concrete pore solution with chlorides.

Evaluation of Corrosion Resistance and Passive Film Properties of Industrial Chromium Plating by Immersion Potential Monitoring

Evaluation of Corrosion Resistance and Passive Film Properties of Industrial Chromium Plating by Immersion Potential Monitoring

Elucidation of the corrosion rate enhancement mechanism in Mg–Er–Gd–Ni alloys with high volume fraction of LPSO phase and different Gd contents after extrusion

The microstructure evolution and corrosion mechanism of Mg–9Er–xGd–2Ni alloys, subjected to Gd addition and extrusion, were investigated in this study. Results shows that with the increase in Gd content from 1.0 wt.% to 5.0 wt.%, the second phase change from continuous network LPSO phase with intragranular γʹ phase to a monolithic continuous network LPSO phase, while the corresponding volume fraction of the second phase remains essentially unchanged. Moreover, it is noted that increasing Gd content contributed to a reduction in the corrosion rate of alloy by reducing galvanic corrosion couples and facilitating the formation of double Gd2O3 and Er2O3 corrosion-resistant films. Ultimately, what's most noteworthy is that compared with as-cast alloys, the corrosion rate of as-extruded alloys increased by 49.2%–125.3% with increasing Gd content, which is due to the streamlined LPSO phase distribution weakening the corrosion barrier effect of high-volume fraction network distribution LPSO phase alloy and grain refinement providing more corrosion interfaces that inhibited the formation of corrosion-resistant product films. This study provides new provides new insights for the development of highly degradable Mg–Er–Gd–Ni alloys that have high strength potential for applications in unconventional oil and gas extraction.

Preparation of corrosion-resistant surface of magnesium alloy and its performance study

The susceptibility of magnesium alloys to corrosion has hindered the wide application of magnesium alloys. A natural green method was proposed in this study to prepare a corrosion-resistant film layer whose main substance is MgO on the magnesium alloy substrate by a two-step hydrothermal method combining water steaming and annealing treatment. The morphology, composition, structure and corrosion resistance of the coating were investigated by SEM, FTIR, XRD and electrochemical methods. The results showed that the prepared coating has excellent corrosion resistance, reducing corrosion current by about four orders of magnitude compared with the bare Mg alloy substrate, and the corrosion potential and corrosion rate are also increased in different degree.

Corrosion and passivation behavior of Ti-6Al-4V surfaces treated with high-energy pulsed laser: A comparative study of cast and 3D-printed specimens in a NaCl solution

This study explores using high-energy pulsed laser to improve the surface property and corrosion behavior of Ti-6Al-4V, aiming to develop a more eco-friendly and efficient approach. The study comprises conventional cast samples, advanced 3D-printed samples, and their respective laser-treated counterparts, all tested in a 3.5 wt% NaCl solution. The findings showed that sample 3 (as-3D-printed) had a more stable passivation film than sample 1 (as-cast). The laser-treated surface of sample 2 (laser-treated cast) greatly enhances film stability and resistance. Moreover, sample 4 (laser-treated 3D-printed) exhibited significantly better corrosion performance compared to sample 3 (as-3D-printed) due to the increased thickness of the passivation film in the laser-treated samples, resulting in higher film corrosion resistance. The results reveal that laser remelting treatment can eliminate macroscopic defects, reduce grain size, increase grain boundary density, and generate denser and more stable passivation films on the surface of Ti-6Al-4V, leading to reduced corrosion currents during dynamic potential polarization. Furthermore, laser remelting treatment has the capability to transform and refine the α phase into a finer lamellar and needle-like structure, thereby increasing the density of passivation nucleation sites during the corrosion process, resulting in the formation of a high-density passivation layer, and ultimately improving the corrosion resistance. By gaining a better understanding of the underlying mechanisms involved in high-energy pulsed treatment, this work provides valuable insights that can be used to optimize the treatment process and improve the overall surface properties of Ti-6Al-4V alloys.

Enhancing corrosion resistance of additive manufactured heterogeneous martensite stainless steel by hot isostatic pressing

The effect of hot isostatic pressing (HIP) on microstructure, corrosion resistance and passive film characteristics for heterogeneous martensite stainless steel (MSS) manufactured by laser powder bed fusion (LPBF) was studied. The microstructure was mainly typical original austenite grains and martensite laths and the high content of austenite disappeared after HIP. The average grain size (about 14.09 μm) was larger than that of sample before HIP (about 4.33 μm). When the laser power was 170 W and the scanning speed was 550 mm·s−1, the density of the samples after HIP increased to >99.99%. When the scanning speed increased to 1250 mm·s−1, the density of samples increased from 97.82% to 99.89%. After HIP treatment, the passivation trend of low density (97.8%) samples was more obvious and the pitting potential increased from −44 mVSCE to 179 mVSCE. The pitting potential of high density (99.77%) samples increased from 265 mVSCE to 291 mVSCE and the electrochemical impedance value increased. The sensitivity of the samples to chloride ions significantly decreases after HIP. The donor density for sample before HIP was 2.5546 × 1020 cm−3, which was higher than that of sample after HIP (2.001 × 1020 cm−3). Therefore, the corrosion resistance of LPBF high strength stainless steel was enhanced after HIP.

Effect of minor gallium addition on corrosion, passivity, and antibacterial behaviour of novel β-type Ti–Nb alloys

Metastable Ti–Nb alloys are promising bone-implant materials due to improved mechanical biofunctionality and biocompatibility. To overcome increasing bacterial infection risk, alloying with antibacterial elements is a promising strategy. This study investigates the effect of minor gallium (Ga) additions (4, 8 wt% Ga) to as-cast and solution-treated β-type Ti–45Nb-based alloy (96(Ti–45Nb)-4Ga, 92(Ti–45Nb)-8Ga (wt.%)) on corrosion and passive film properties, as well as cytocompatibility and antibacterial activity. The electrochemical properties were evaluated by potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and Mott-Schottky analyses in phosphate-buffered saline (PBS). X-ray photoelectron spectroscopy (XPS) was performed to analyze the chemical composition of passive films. Early adhesion and viability of macrophages and Staphylococcus aureus were assessed by nucleocounting and colony-forming unit counting, respectively. The results showed that high corrosion resistance and passive film properties of Ti–45Nb are retained and even slightly improved with Ga. EIS results revealed that Ga addition improves the passive film resistance. XPS measurements of 92(Ti–45Nb)-8Ga show that the passive film contains Ti-, Nb- and Ga-based oxides, implying the formation of mixed (Ti–Nb-Ga) oxides. In addition, marginal Ga ion release rate was detected under free corrosion conditions. Therefore, it can be assumed that Ga species may contribute to passive film formation on Ga-containing alloys. The 92(Ti–45Nb)-8Ga elicited an antibacterial effect against S. aureus compared to cp-Ti at 4 h. Moreover, Ga-containing alloys showed good cytocompatibility with THP-1 macrophages at 24 h. In conclusion, it was demonstrated that Ga additions to Ti–45Nb are beneficial to corrosion resistance and showed promising initial host and bacterial interactions.