Enhanced Corrosion Resistance Research Articles

Microstructure, mechanical and corrosion behavior of CrNx/Al2O3 multilayer films deposited by magnetron sputtering

A novel design was adopted to improve corrosion resistance of 2024 Al alloys by magnetron sputtering CrNx based multilayer films with Al2O3 intercalation. The multilayer films were composed of inhomogeneous structure, i.e., thick CrNx transition layer (∼2 μm) + CrNx/Al2O3 multilayer (∼1 μm). The effect of Al2O3 interlayer and modulation period on microstructure and performance of multilayer films were investigated. The nitride layer was dominated by Cr2N and CrN with minor Cr, while the Al2O3 layer displayed in the amorphous form. The intercalation of Al2O3 blocked the columnar growth in CrNx layers and refined the grains. As the period increased, the cluster particle size decreased and the mechanical properties increased, with the maximum hardness and modulus at CN-8 (19.13 GPa and 282.2 GPa). In addition, the multilayer structure enhanced the bonding between the film and the substrate, and has an improvement on the hard and brittle properties of the film. The multilayer films showed improved corrosion resistance than the CrNx mono-layer in 3.5 wt% NaCl solution. The film with CrNx-top layer showed superior corrosion resistance than the film with Al2O3-top layer. The increasing period also enhanced corrosion resistance, showing an excellent corrosion potential and corrosion current density (Ecorr=-0.538 V, icorr=0.96 μA·cm−2) at CN-8.

Effect of loading level on the corrosion resistance of a novel self-healing cementitious composite

A novel self-healing cementitious composite SMA-ECC is utilized to enhance corrosion resistance and maintain mechanical properties in chloride environment. The purpose of this study is to investigate the impact of the loading level on embedded steel rebar corrosion and the self-healing performance of SMA-ECC. The study examined the damage conditions, mechanical properties, and rebar corrosion resistance following a loading test. Chloride ingress depth and electrochemical tests were adopted to evaluate the corrosion resistance of the specimens. The findings reveal that SMA-ECC exhibits remarkable self-healing abilities in terms of damage recovery and restoration of mechanical properties. Cracks smaller than 50 μm can achieve a 100 % closure rate in SMA-ECC. It was observed that specimens with less damage (50 %, 70 % damage conditions) displayed improved chloride resistance (SMA-ECC in 50 % damage condition has equivalent corrosion resistance in terms of corrosion current density compared to intact NC control specimens), leading to higher corrosion resistance for SMA-ECC according to the electrochemical test results.

Synthesis and Characterization of Superhydrophobic Epoxy Resin Coating with SiO2@CuO/HDTMS for Enhanced Self-Cleaning, Photocatalytic, and Corrosion-Resistant Properties.

The exceptional corrosion resistance and combined physical and chemical self-cleaning capabilities of superhydrophobic photocatalytic coatings have sparked significant interest among researchers. In this paper, we propose an economical and eco-friendly superhydrophobic epoxy resin coating that incorporates SiO2@CuO/HDTMS nanoparticles modified with Hexadecyltrimethoxysilane (HDTMS). The application of superhydrophobic coatings effectively reduces the contact area between the metal surface and corrosive media, leading to a decreased corrosion rate. Additionally, the incorporation of nanomaterials, exemplified by SiO2@CuO core-shell nanoparticles, improves the adhesion and durability of the coatings on aluminum alloy substrates. Experimental data from Tafel curve analysis and electrochemical impedance spectroscopy (EIS) confirm the superior corrosion resistance of the superhydrophobic modified aluminum alloy surface compared to untreated surfaces. Estimations indicate a significant reduction in corrosion rate after superhydrophobic treatment. Furthermore, an optical absorption spectra analysis of the core-shell nanoparticles demonstrates their suitability for photocatalytic applications, showcasing their potential contribution to enhancing the overall performance of the coated surfaces. This research underscores the promising approach of combining superhydrophobic properties with photocatalytic capabilities to develop advanced surface modification techniques for enhanced corrosion resistance and functional properties in diverse industrial settings.

Application of AIE luminogen-loaded core–shell fibers in self-warning and self-healing polymer coatings with enhanced corrosion resistance

Aggregation-induced emission (AIE) materials have been used for non-destructive visual detection of cracks and damages to prevent the final structural failure and increase the service life of coatings. In this study, a self-warning and self-healing core–shell fiber is synthesized for developing AIE composite coatings. In these core–shell fibers, a mixture of hmethylene diisocyanate (HDI) and tetraphenylethylene (TPE) is used as core constituent, and polyacrylonitrile (PAN) is used for preparing the shell, which are continuously wrapped with a high loading rate through coaxial electrospinning technology. The parameters of electrospinning process are optimized to achieve core–shell fibers with smooth surface and average diameter of 100 ± 50 nm. The composite coating reveals effective fluorescence in case of cracks in a corrosive environment. The maximum self-healing efficiency of the fiber coating is 94.8 % after soaking for 120 h. The introduced composite coating paves the way for improving the safety and reliability of critical engineering components.

Essential role of Si in enhancing corrosion resistance of high strength low alloy steels in marine environment

High strength low alloy steels are extensively applied in marine engineering structures (cross-sea bridge, ocean platform, etc), which are usually subjected to severe corrosion in marine atmosphere. In this work, the corrosion behaviors of 550 MPa-grade high strength low alloy marine steels with varied Si content were studied in simulated marine atmosphere. Results show the increase of Si could significantly facilitate the formation of α-FeOOH and enrichment of Cr and Cu in inner rust layer, making the rust layer compact and cation-selective. Si and Cr can be co-enriched in inner rust layer to form mixed or complex oxides with amorphous network structure, which could greatly improve the compactness and stability of rust layer and thereby enhance the corrosion resistance of low alloy steel.

Hybrid inorganic-organic capsules encapsulated FeNi with enhanced corrosion resistance and microwave absorption

Responding to the critical need for stable microwave absorption (MA) devices in complex and extreme environments, dual-function electromagnetic wave absorbers have garnered significant attention. Addressing this, we developed a novel FeNi-based composite encapsulated within superhydrophobic SiO2@Perfluorooctyltriethoxysilane (F13)/Methyltrimethoxysilane (MTMS) hybrid capsules, approximately 28-nm-thick, utilizing a straightforward one-pot strategy. This innovative FeNi@SiO2@F13/MTMS composite surpassed pure FeNi, exhibiting an effective MA bandwidth of 8.16 GHz and a minimal reflection loss value of −24.03 dB at 2.00 mm. It also boasted the largest radar scattering cross-section reduction value recorded at 21.09 dB m2. The enhanced MA properties were primarily attributed to the SiO2@F13/MTMS, which significantly improved the substrate's impedance matching. In addition to facilitating multiple scattering and reflection, it also triggered dipole and interfacial polarization. Moreover, the SiO2@F13/MTMS layer was instrumental in reducing the corrosion current density of FeNi from 3.512 mA cm2 to 5.59 nA cm2, thereby demonstrating exceptional corrosion resistance. This remarkable improvement was largely due to the surface hydrophobicity and the barrier effect provided by the hybrid capsules. Our exploration into corrosion-resistant and efficient MA materials provides valuable insights for the rational design of bifunctional components tailored for specific applications.

GPa-level pressure-induced enhanced corrosion resistance in TiZrTaNbSn biomedical high-entropy alloy

GPa-level pressure-induced enhanced corrosion resistance in TiZrTaNbSn biomedical high-entropy alloy

Localized corrosion characteristics of Al-Mg-Si aluminum alloy with aging time and pre-delayed aging condition

The effects of single aging, delayed aging and pre-delayed aging treatment on the corrosion resistance of Al-Mg-Si alloy were studied by scanning Kelvin probe force microscopy (SKPFM), transmission electron microscopy (TEM), scanning electron microscopy (SEM), three-dimensional X-ray tomography (3D-XRT), confocal laser scanning microscopy (CLSM) and electrochemical measurements. The surface potentials of Al(MnFe)Si, Mg2Si, and Si-rich remnant phases are determined, identifying Al(MnFe)Si phase as the crucial cathodic site for corrosion initiation, and the increase in surface potential implies an accelerated corrosion rate after immersion. The intergranular corrosion susceptibility of the alloy is predominantly influenced by the microstructure caused by aging conditions. The factors affecting corrosion resistance are summarized as (i) adjustment of electrochemical reaction activity by controlling the area fraction of Al(MnFe)Si phase, (ii) the spacing of grain boundary precipitates (GBPs), and (iii) the width of the precipitation-free zone (PFZ). The delayed aging (DA) sample exhibits inferior corrosion resistance due to the continuous GBPs and extended sub-grain boundaries corrosion propagation paths. The pre-delayed aging treatment successfully mitigates the corrosion degree of DA by widening the GBPs spacing and narrowing the PFZ width. This suggests that pre-aging treatment is a potent strategy for enhancing corrosion resistance without compromising the alloy's strength.

Corrosion behavior of Nb-doped FeCrAl alloy in 500°C steam

The corrosion behavior of Fe-13Cr-4Al-2.2Mo, a candidate cladding material for accident tolerant fuel, doped with varying concentrations of Nb (0, 0.5, 1.0, and 1.5 wt%), was investigated under conditions of 500°C/10.3 MPa superheated steam. Upon exposure, a triple-layer oxide film comprising outer, inner, and diffusion oxide layers was formed. The results indicate that the addition of Nb significantly enhances the corrosion resistance of this alloy by reducing the thickness and porosity of the oxide film. The enhanced volume diffusion rate of Al and Cr, facilitated by the solid solution Nb, along with the inhibited inward diffusion of oxidant ions along grain boundaries owing to Laves phase precipitates, contributed to the enhanced corrosion resistance of the Nb-doped Fe-13Cr-4Al-2.2Mo alloy.

Unraveling the effects of nano-grained microstructure on mechanical behavior, corrosion, and in vitro biocompatibility of 316L austenitic stainless steel

Nanograins are often beneficial in achieving better cytocompatibility for metallic implants. In this work, we have achieved grains from the micro to nano range in 316L austenitic stainless steel by a combination of cryo-rolling (50%, 70%, and 90% thickness reduction) followed by annealing (750–1000 °C for 2–20 min). The combined effect of grain refinement along with texture on its mechanical, corrosion, and in vitro cellular behavior was thoroughly investigated. Microstructural observations revealed nanograins formation (grain size = 144 nm) only for the 90CRA sample, whereas grain refinement in the micron range was observed for 0-70CRA samples. Electron backscatter diffraction (EBSD) studies showed fully austenitic structures for all the annealed samples while low Kernel Average Misorientation (KAM) values indicated strain-free microstructures. Orientation distribution function (ODF) maps showed the presence of strong γ-fiber (<111>||ND) and weak α-fiber (<110>||ND) in the 90CRA sample. The grain refinement led to an increase in the yield strength and ultimate tensile strength from 470.6 ± 16.21 MPa and 858.35 ± 31.82 MPa (0CRA) to 1662.06 ± 58.44 MPa and 2112.3 ± 51.62 MPa (90CRA), respectively. The potentiodynamic polarization study revealed that the corrosion rate of the 90CRA sample was about eight times less than that of the 0CRA sample. This was further corroborated by Mott-Schottky analysis, which showed a lowering of both acceptor and donor densities with the reduction in grain size. The evolution of a strong <111> texture during cryo-rolling contributed towards enhanced corrosion resistance of nano-grained 316L. Furthermore, grain refinement improved wettability, which in turn led to better cell proliferation and differentiation. At all culture days, MC3T3-E1 cell proliferation and differentiation were considerably higher for nano-grained 316L micron-sized counterparts. Thus, grain refinement to the nano range is an effective technique for the property enhancement of biomedical implants.

Design multifunctional Mg–Zr coatings regulating Mg alloy bioabsorption

Magnesium (Mg) alloys are widely used for temporary bone implants due to their favorable biodegradability, cytocompatibility, hemocompatibility, and close mechanical properties to bone. However, rapid degradation and inadequate strength limit their applicability. To overcome this, the direct current magnetron sputtering technique is employed for surface coating in Mg-based alloys using various zirconium (Zr) content. This approach presents a promising strategy for simultaneously improving corrosion resistance, maintaining biocompatibility, and enhancing strength without compromising osseointegration. By leveraging Mg's inherent biodegradability, it has the potential to minimize the need for secondary surgeries, thereby reducing costs and resources.This paper is a systematic study aimed at understanding the corrosion mechanisms of Mg–Zr coatings, denoted Mg-xZr (x = 0–5 at.%). Zr-doped coatings exhibited columnar growth leading to denser and refined structures with increasing Zr content. XRD analysis confirmed the presence of the Mg (00.2) basal plane, shifting towards higher angles (1.15°) with 5 at.% Zr doping due to lattice parameter changes (i.e., decrease and increase of “c” and “a” lattice parameters, respectively). Mg–Zr coatings exhibited “liquidphilic” behavior, while Young's modulus retained a steady value around 80 GPa across all samples. However, the hardness has significantly improved across all samples’ coating, reaching the highest value of (2.2 ± 0.3) GPa for 5 at.% Zr. Electrochemical testing in simulated body fluid (SBF) at 37 °C revealed a significant enhancement in corrosion resistance for Mg–Zr coatings containing 1.0–3.4 at.% Zr. Compared with the 5 at.% Zr coating which exhibited a corrosion rate of 32 mm/year, these coatings displayed lower corrosion rates, ranging from 1 to 12 mm/year. This synergistic enhancement in mechanical properties and corrosion resistance, achieved with 2.0–3.4 at.% Zr, suggests potential ability for reducing stress shielding and controlled degradation performance, and consequently, promising functional biodegradable materials for temporary bone implants.

Microstructure, thermal/mechanical properties and corrosion behaviors of ternary and quaternary equimolar rare-earth monosilicates

The properties of rare-earth (RE) monosilicates can be regulated by solid solution engineering based on the mixture rule. The combination and number of RE principals are critical factors for better performances. In the present study, four single-phase equimolar multicomponent RE-monosilicate solid solutions including (Dy1/3Er1/3Yb1/3)2SiO5, (Ho1/3Er1/3Yb1/3)2SiO5, (Y1/4Er1/4Tm1/4Lu1/4)2SiO5 and (Dy1/4Er1/4Tm1/4Yb1/4)2SiO5 were synthesized by solid-state reaction and hot-pressing method. The microstructures, thermal and mechanical properties, and corrosion resistance to high-temperature water vapor were systematically investigated. Compared to the single-principal and ternary RE-monosilicates, the quaternary RE-monosilicates exhibited lower thermal conductivity of 1.32 Wm−1K−1 at 400 °C, matched thermal expansion coefficients (3.3 × 10−6/oC ∼ 5.8 × 10−6/oC from 200 °C to 1000 °C) with SiC, and much lower weight loss during water vapor corrosion. The results indicate that the increase of the RE element number can promote the grain growth, lower the thermal conductivity and thermal expansion coefficient, and enhance corrosion resistance.

Diatomite@MoS2 Nanocomposite Layers as Composite Coating Targeting for Mg Alloys Endowed with Properties of Anticorrosion and Antiwear.

Molybdenum disulfide (MoS2) demonstrates promising applications in enhancing the corrosion and wear resistance of metals, but the susceptibility of this nanomaterial to agglomeration hinders its overall performance. In this study, the externally assisted corrosion inhibitor sodium molybdate (SM) was successfully constructed in diatomaceous earth (DE) and molybdenum disulfide (MoS2). This not only served as a molybdenum source for MoS2 but also enabled the preparation of DE@MoS2-SM microcapsules, achieving a corrosion inhibitor loading of up to 23.23%. The corrosion testing reveals that the composite coating, when compared to the pure epoxy coating, exhibits an impedance modulus 2 orders of magnitude higher (1.80 × 109 Ω·cm2), offering prolonged protection for magnesium alloys over a 40 day period. Furthermore, a filler content of 3% sustains a coefficient of friction (COF) at 0.55 for an extended duration, indicating commendable stability and wear resistance. The protective performance is ascribed to the synergistic enhancement of corrosion and wear resistance in the coatings, facilitated by the pore structure of DE, the high hardness of MoS2, and the obstructive influence of Na2MoO4. This approach offers a straightforward and efficient means of designing microcapsules for use in corrosive environments, whose application can be extended in industrial fields. In particular, we promote the application of nautical instruments, underwater weapons, and seawater batteries in the shipbuilding industry and marine engineering.

Theoretical explanation of passivation behavior in OFP-Cu and OF-Cu

This research presents a comprehensive comparative analysis of the passivation kinetics of OFP-Cu and OF-Cu in simulated repository electrolyte. The study employs a range of techniques, including potentiodynamic polarization, multi-step potentiostatic polarization, electrochemical impedance spectroscopy, and Mott-Schottky analysis, to explore the intricacies of corrosion behavior. The Point Defect Model (PDM) is used to interpret the steady-state physicochemical processes. Utilizing the results of PDM optimization, defect distribution diagrams within the passivation film were constructed, shedding light on the pivotal transition from p-type to n-type semiconductor properties of the film. The study concludes with an interpretation of the experimental data, highlighting the enhancement of copper's corrosion resistance due to phosphorus doping, as elucidated by the Solute-Vacancy Interaction Model.

Empowering PVD for corrosion protection

SummaryA novel, monolithic DC‐magnetron sputtered TiN+MgGd coating, only 3to5 μm thick, effectively protects steel substrates from corrosion. This achievement is due to alloying of TiN with MgGd, which not only maintains the renowned wear resistance of TiN coatings, but potentially improves it through optimized deposition parameters.The key to the enhanced corrosion resistance lies in the addition of magnesium (Mg) and gadolinium (Gd). It reduces the coating's free corrosion potential, thereby mitigating the driving force for galvanic corrosion between coating and substrate. Moreover, at specific Mg to Gd ratios, a cathodic protection effect can be observed. Crucially, the presence of Gd is essential for this performance. It imparts hydrophobicity to the coating surface, reinforces a passivating layer and significantly enhances defect tolerance.This discovery paves the way for a sustainable alternative to electroplated chromium or combined electroplating and PVD, offering superior corrosion protection with minimal coating thickness.

Structural, mechanical, wear and anticorrosive properties of CrSiCN coatings used for industrial woodworking applications

The woodworking applications are a fast-growing field that aims to create advanced coatings with superior wear resistance, reduced friction, and robust corrosion protection. Chromium silicon carbonitride (CrSiCN) coatings have emerged as a promising solution that offers a unique combination of properties ideal for various industrial applications. The C/N ratio significantly influences the coatings' mechanical and tribological properties. By optimizing the C/N ratio, this research aims to reveal new insights for CrSiCN coatings, enhancing their application in environments that require durability, efficiency, and longevity. In this paper, the effect of the C/N ratio on the structural, mechanical, and corrosion resistance of CrSiCN coatings deposited by cathodic arc evaporation on different steel substrates was studied. The main purpose was to enhance the mechanical and anticorrosion properties of the CrSiCN coatings and to select the optimum parameters for the deposition of layers with superior properties. The results showed that the final properties can be tailored by choosing specific deposition conditions. In this case, the C/N ratio proved to be critical since coatings with higher carbon content presented enhanced corrosion resistance, being able to withstand operating conditions similar to real-life.

Effect of Cr on the corrosion behavior of low carbon vanadium micro alloyed weathering steel in a simulated industrial atmosphere

AbstractThe study investigates the practical application of cyclic wet/dry corrosion tests in simulated industrial atmospheres to assess the impact of chromium (Cr) on the protective properties of vanadium micro‐alloyed weathering steels. Two types of steels were examined: a V‐N steel and a V‐N‐Cr micro‐alloyed weathering steel. These steels were subjected to corrosion tests with 0.01 mol/L NaHSO3 at a pH range of 4.4–4.8 for varying durations. The findings indicate that the inclusion of Cr in the composition of vanadium micro‐alloyed weathering steel enhances corrosion resistance and leads to the accumulation of Cr in the inner rust layer. Furthermore, the distribution of corrosion‐resistant elements (Cr, Ni, Cu, P, and Mo) in V‐N and V‐N‐Cr steels is analyzed. The rust layer was observed to exhibit stratification in the corrosive environment, with the outer layers being dense and uniform, while the inner layers were porous and exhibited poor adhesion to the matrix. The study also delves into the anticorrosion mechanism of vanadium weathering steel using techniques such as X‐ray diffractometer, electron probe microanalysis, and potential‐phase diagram.

Effect of Heat Treatment on the Electrochemical and Tribological Properties of Aluminum-Bronze Coatings Deposited Used the Thermal Spraying Process

The corrosion and wear resistance of aluminum-bronze coatings deposited by thermal flame spraying were investigated after a 10 h heat treatment at 500 °C in a nitrogen atmosphere. The coatings were characterized by SEM, EDS, XRD, and XRF. Corrosion resistance was evaluated by Tafel and EIS tests, while wear resistance was assessed using a ball-on-disc test. Results showed the heat treatment compacted the coating microstructure, increased oxide content, and improved splat bonding through diffusion mechanisms. This led to enhanced corrosion resistance, evidenced by reduced corrosion current density in electrochemical tests, resulting from densification impeding electrolyte penetration. Heat treatment also increased wear resistance, as indicated by lower wear rates in ball-on-disc tests, attributable to increased hardness, reduced friction coefficients, and annealing-induced microstructural changes. Overall, the heat treatment optimizes the anticorrosive and tribological properties of thermally sprayed aluminum-bronze coatings via favorable alterations in composition, morphology, and physical characteristics. The research provides a new understanding of how thermal spray parameters and post-deposition heat treatment can be utilized to enhance the corrosion and wear resistance of aluminum-bronze coatings for marine applications.

Environmentally friendly synthesis and characterization of copper nanoparticles using amino acids as capping agents: enhanced corrosion resistance and morphological control

Environmentally friendly synthesis and characterization of copper nanoparticles using amino acids as capping agents: enhanced corrosion resistance and morphological control

Effect of substrate’s surface roughness on corrosion and wear rate of Ni-GO nanocomposite coating

Corrosion is a natural process that occurs when refined metal is converted into a more stable form, such as oxide, hydroxide, or sulfide. Wear is the failure of a surface due to dynamic contact between two surfaces. In offshore operations and environments, corrosion and wear are major problems due to the presence of corrosive and abrasive elements. The coating is a common surface protection method that enhances corrosion resistance and prolongs lifespan. In this work, a Ni-Graphene nanocomposite coating was fabricated using the electrodeposition method. This work aimed to fabricate a Ni-GO nanocomposite coating on mild steel with different surface roughness, to characterize the physical, mechanical, and chemical properties of the coating, and to investigate its corrosion and wear rate. The fabrication process involved preparing substrates coated with Ni-GO nanocomposite through a 45-minute constant current electrodeposition process. The coated specimens were characterized using X-Ray Diffraction Machine (XRD), Scanning Electron Microscope (SEM), Alicona Infinite Focus, Vicker’s Hardness Test, Raman spectroscopy, and Adhesion test. The corrosion and wear rate of the coatings were investigated using a Slurry Erosion tester and Salt Water spray, respectively. The results showed that the Ni-Go nanocomposite coating on a smooth surface roughness substrate achieved the highest microhardness, wear resistance, and corrosion resistance, with values of 468.8 HV, 0.182% weight loss, and 0.03% weight gain, respectively. This indicates that the specimen coated with a smooth surface roughness substrate provided better coating performance than the rough and medium surface roughness substrates.