Corrosion Resistance Research Articles

Triple Corrosion Protection: Dual-Layer Coating with Simultaneous Superhydrophobicity, Intelligent Self-Healing, and Shape Memory.

In this paper, a self-healing superhydrophobic smart two-layer coating, ZOA/SMP-S, was developed. ZIF-8 was surface hydrophobically modified by octadecylphosphoric acid (OPA) to obtain Z-OPA and then encapsulated with a corrosion inhibitor, AMT ( 2-Amino-5-mercapto-1,3,4-thiadiazole), to obtain the superhydrophobic nanocontainers, ZOA. ZOA was embedded into the SMP (shape memory coating) to obtain the smart coating, and Z-OPA was sprayed to obtain the second superhydrophobic coating. SEM showed that the scratch coatings were rapidly reduced by scratches after a simple heat treatment. The prepared composite coatings showed excellent performance in corrosion inhibitor release, immersion, superhydrophobicity, and self-healing experiments. The contact angle of the superhydrophobic coating reached 158.2°, and the sliding angle was 2.8°. The low-frequency impedance value |Z|f=0.01Hz of ZOA/SMP-S is as high as 1.58 × 1010 Ω·cm2 after 40 days of immersion test, which indicates that the triple protection greatly enhances the corrosion resistance of the coating.

On the Improved Mechanical Properties and Corrosion Resistance in LM6 Alloy Through Eutectic Modification

On the Improved Mechanical Properties and Corrosion Resistance in LM6 Alloy Through Eutectic Modification

Effect of a Novel Heat Treatment on the Corrosion Resistance of Duplex Stainless Steel S32101

Effect of a Novel Heat Treatment on the Corrosion Resistance of Duplex Stainless Steel S32101

Protection of stainless steel surfaces in desalination units against corrosion during acid cleaning under dynamic conditions by using lavender angustifolia extract as a green inhibitor

This study investigates the thermodynamics, kinetics, and adsorption mechanisms of Lavender angustifolia extract (LAE) as a corrosion inhibitor for stainless steel (316SS) in desalination units. The primary aim is to evaluate the efficacy of LAE in mitigating corrosion in a 5.0 M HCl solution under dynamic conditions. High-Performance Liquid Chromatography (HPLC) analysis identified key components of the LAE extract that contribute to corrosion inhibition, including linalyl acetate (41.7%), linalool (13.6%), 1,8-cineole (8.3%), β-ocimene (6.2%), terpinen-4-ol (5.7%), lavandulyl acetate (7.5%), and camphor (4.7%). Results indicate that the inhibitory efficiency of LAE increases with concentration, peaking at 94.3% at 300 mg L⁻¹. The Freundlich adsorption isotherm model best describes the experimental adsorption data. Notably, the activation energy for corrosion increases from 7.17 kJ mol⁻¹ in the 5.0 M HCl solution to 21.65 kJ mol⁻¹ with the addition of LAE, reflecting enhanced protection. The enthalpy change (∆H*) in the presence of LAE (19.04 kJ mol⁻¹) is significantly greater than that of the extract-free solution (4.55 kJ mol⁻¹), indicating improved corrosion resistance of 316SS. Electrochemical techniques confirmed the mixed-type inhibition behavior of LAE, while UV and SEM-EDAX analyses demonstrated effective adsorption of the extract on the stainless steel surface.

Improving Bioactivity and Corrosion Resistance of Laser-Powder-Bed-Fused Ti6Al4V with Hydroxyapatite and Titanium Oxide Nanocomposite Coatings Applied by Electrophoretic Deposition

Improving Bioactivity and Corrosion Resistance of Laser-Powder-Bed-Fused Ti6Al4V with Hydroxyapatite and Titanium Oxide Nanocomposite Coatings Applied by Electrophoretic Deposition

The Impact of Pre- and Post-Treatment Processes on Corrosion Resistance of Micro-Arc Oxidation Coatings on Mg Alloys: A Systematic Review

As one of the lightest metallic structural materials, magnesium (Mg) alloys possess numerous distinctive properties and are utilized across a broad spectrum of applications. However, the poor corrosion resistance of Mg alloys limits their application. Micro-arc oxidation (MAO) is an effective surface treatment method that enhances the corrosion resistance of Mg alloys. Nevertheless, the intrinsic porous structure of MAO coatings hinders significant improvement in corrosion resistance. Research indicates that the pre- and post-treatment processes associated with MAO markedly enhance the densification of the oxide coatings, thereby improving their overall performance. This paper aims to provide a comprehensive review and analysis of the effects of various pre- and post-treatment processes, highlighting key advancements and research gaps in improving MAO coatings on Mg alloys. An in-depth analysis of the crucial role of pre-treatment in optimizing interfacial bonding and post-treatment in enhancing coating density is conducted using electrochemical testing and scanning electron microscopy (SEM). Finally, the future development of pre- and post-treatment processes are discussed.

Enhancing Mechanical and Biodegradation Properties of Zn-0.5Fe Alloys Through Rotary Forging

The rising prevalence of orthopedic conditions, driven by an aging population, has led to a growing demand for advanced implant materials. Traditional metals such as stainless steel and titanium alloys are biologically inert and often necessitate secondary surgical removal, imposing both economic and psychological burdens on patients. Biodegradable zinc-based alloys offer promising alternatives due to their moderate degradation rates, biocompatibility, and tissue-healing properties. However, existing studies on Zn-Fe alloys primarily focus on composition optimization, with limited investigation into how processing methods influence their performance. This study explores the effects of rotary forging on the microstructure and mechanical properties of Zn-0.5Fe alloys. By refining grain structure and promoting dynamic recrystallization, rotary forging achieves significant improvements in ductility (60% elongation, a 114% increase compared to the extruded state) while maintaining corrosion resistance. Electrochemical and immersion tests reveal that rotary forging produces a denser and more protective corrosion layer, thereby improving the degradation performance of the material in simulated body fluid. Cytotoxicity and fluorescence staining tests confirm excellent biocompatibility, validating the material’s suitability for medical applications. These findings elucidate the mechanisms by which rotary forging enhances the properties of Zn-0.5Fe alloys, providing a novel approach to tailoring biodegradable implant materials for orthopedic applications.

A combined approach of melt pool ultrasonic vibration and inter-pass laser re-melting for achieving superior mechanical properties by controlling microstructure and phases in L-DED of Inconel 625

Abstract Laser Direct Energy Deposition (DED) is an additive manufacturing technique used in aerospace, automotive, nuclear industries. However, challenges such as porosity, cracks, microstructural inhomogeneity, elemental segregation, usually affect the mechanical properties of fabricated components. This study proposes the synergistic application of ultrasonic vibration and inter-pass laser re-melting in DED of Inconel 625 to effectively address these issues. Ultrasonic vibration to the melt pool results in equiaxed structures and reduces micro-pores by inducing acoustic streaming and cavitation effects, whereas inter-pass laser re-melting selectively melts the previously deposited layers and reduces porosity. Both the techniques influence the formation and distribution of intermetallic within the deposition. A synergistic application of these methods led to minimal porosity and equiaxed grains with thinner grain boundaries. Phase analysis revealed significant presence of similar intermetallic compounds in as-deposited and vibration-assisted samples, with (γ′) phase appearing specifically in re-melted and combined techniques. Further, intermetallic compounds, which were randomly distributed in as-deposited and re-melted conditions, were found predominantly near the grain boundaries when vibration was applied alone or with re-melting, resulting in better mechanical properties. The synergistic effect led to ∼20% increase in micro-hardness, ∼75% reduction in wear rate, ∼32% higher ultimate tensile strength, ∼25% increase in strain, and significantly enhanced corrosion resistance compared to as-deposited samples. This study underscores the potential of using ultrasonic vibration and inter-pass re-melting synergistically to enhance overall performance of DED-fabricated Inconel 625 components, outperforming their individual effect.

A Sustainable Microstructure Modification‐Based Design of Al‐Si Alloys for Energy Efficient Electric Power Transmission and Distribution

Power transmission and distribution systems need to be more efficient and sustainable to meet the growing electricity demand. The high conductivity of aluminum alloys is advantageous for power transmission. The present work demonstrates how the size, shape, and distribution of phases influence the electrical and thermal conductivity of a hypoeutectic Al‐Si alloy power connector. The addition of Al‐10 wt% Sr to Al‐10.5 wt% Si reduces the size of eutectic Si from 15 ± 8 μm to 0.75 ± 0.2 μm and β‐(Al‐Fe‐Si) phases from 52.85 ± 7 μm to 35.79 ± 3 μm, while slightly increasing the secondary dendrite arm spacing from 40.5 ± 3 μm to 55.2 ± 5 μm. These modifications increase the thermal conductivity from 111 to 127 W mK−1, which enhances the current density of the power connector assembly from 1.7 × 107 to 2.1 × 107 A m−2, improving its ampacity. Additionally, the Sr‐modified alloy exhibits superior corrosion resistance, with the corrosion rate decreases from 0.0416 to 0.012 mm year−1. These results are supported by finite element simulations and experimental validation, which show that microstructure optimization enhances electrical and thermal conductivity while reducing energy losses. This approach lowers the electricity demand, decreases greenhouse gas emissions, and minimizes the environmental impact of frequent replacements.

Mechanical Properties and High-Temperature Steam Oxidation of Cr/CrN Multi-Layers Produced by High-Power Impulse Magnetron Sputtering

In this study, Cr coatings, CrN coatings, and CrN/Cr multi-layer coatings were deposited on the surface of Zr-4 alloy by high-power impulse magnetron sputtering (HiPIMS). We have investigated the effect of coating structure on the microstructure, mechanical properties, and high-temperature steam oxidation properties of coatings. The results show that the single-layer CrN coating has higher hardness but performs poorly in high-temperature steam oxidation compared to the Cr coating due to its greater brittleness, which makes it prone to cracking and spalling in high-temperature steam environments and provides a channel for Zr diffusion. In multi-layer coatings, however, they form a fine columnar crystal structure and a smoother surface, and the more layers there are, the better the mechanical properties and resistance to high-temperature steam oxidation of the coating. In a high-temperature steam environment, the CrN layer decomposes to form Cr2N and N2, and the N atoms diffuse inwards and react with Zr to form an α-Zr(N) layer, which restricts interdiffusion between Cr and Zr and blocks the diffusion of O into the substrate. Therefore, (CrN/Cr)n coatings with a multi-layer structure have excellent high-temperature steam corrosion resistance.

Characteristics and properties of hot-deformed duplex stainless steel 2205: An overview

Abstract This overview details the characteristics and attributes of hot-deformed Duplex Stainless Steel (DSS) 2205, emphasizing its phases, alloying elements, and deformation behaviour. Due to its exceptional mix of mechanical qualities and corrosion resistance, it has found extensive applications in water treatment and desalination, chemical industries, oil and gas storage tankers, construction, food production, and marine environments. Its properties during hot deformation are crucial in defining its applications. DSS 2205 features a balanced dual-phase microstructure, with ferrite (α) and austenite (γ) phases in roughly equal quantities, resulting in high mechanical characteristics and corrosion resistance. Depending on the alloy composition and processing conditions, hot deformation can result in the development of secondary phases. Temperature, strain rate, and initial microstructure impact DSS 2205's hot deformation. Hot deformation initiates several forms of grain boundaries, which contribute to microstructural evolution and yielding properties. Therefore, the characteristics of hot-deformed DSS 2205 show a refined and dynamically recrystallized microstructure, resulting in improved properties. Understanding the interaction of alloying components, phases, and deformation conditions can help optimize the hot deformation process for DSS 2205. In conclusion, this study emphasizes optimizing the phases and deformation parameters to fully utilize DSS 2205 in demanding applications.

Fractal, tribo-mechanical and corrosion characterization of hydrophobic and lead free electroless Ni-B mono and bi-layer coating developed using artificial intelligence

Abstract A quaternary, lead free electroless Ni-B-Cu-Sn coating was obtained using experimental design, artificial neural network and genetic algorithm based on higher hardness and deposition rate. A high predicted as-deposited hardness of 1138 HV0.05 and deposition rate of 10 μm hr−1 was achieved. Coating surface had nodular, self-similar fractal nature with higher density for the bi-layered variant. The surface roughness and tribological behaviour was better for the single layered coating. Adoption of double layered coating only had a mild improvement in the corrosion resistance. The bi-layered coatings also exhibit hydrophobic nature with contact angle ∼121°–130°. The first critical load of failure of both the coatings were around 20 N which is nearly like lead stabilized electroless Ni-B coating. This new coating variant can possibly be a newer replacement to the conventional coatings.

Accelerated Destruction of Passive Film and Microbial Corrosion of 316 L Stainless Steel via Extracellular Electron Transfer

AbstractThe dense passive film on 316 L stainless steel is the key in its corrosion resistance. Its interactions with an electroactive biofilm are critical in deciphering microbial corrosion. Herein, an in‐depth investigation using genetic manipulations and addition of an exogenous electron mediator found that extracellular electron transfer (EET) mediated by the electroactive S. oneidensis biofilm grown aerobically accelerated the destruction of the microstructure and weakened the passive film. The changes in surface properties accelerated the electrochemical reactions and increased pitting corrosion. The redox state on the surface also changed due to the activity of the electroactive biofilm. A synergistic EET corrosion mechanism, including both direct and mediated electron transfer with passive film destruction was proposed to illustrate the corrosion caused by electroactive S. oneidensis. The techniques used in this work provide a systematic approach to probe EET impact on microbial corrosion by electroactive biofilms with electron transfer across the biotic‐abiotic interfaces.

Low-temperature growth of wafer-scale amorphous boron nitride films with low-dielectric-constant and controllable thicknesses.

Amorphous boron nitride (aBN) films, with extremely low relative dielectric constant (κ) and chemical inertness, are excellent insulation and packaging materials for electronic device interconnection. It is of great significance to prepare the low-κ aBN films with controllable thickness, but there are still some limitations to achieve the goal. In this study, we succeed in growing wafer-scale aBN films with specific thicknesses from 1.2 to 4.0 nm by varying the growth time and temperature. The thickness of the films increases linearly with growth time and the crystallinity of BN films is precisely controlled by the growth temperature. The preferred temperature for aBN films ranges from 200 to 400 °C. Raman spectroscopy, X-ray photoelectron spectroscopy and transmission electron microscope all confirm the amorphous feature. These films are wafer-scale uniformity and have an ultra-flat surface, with excellent thermal stability and corrosion resistance. Particularly, the growth temperature affects the κ value and breakdown voltage of aBN films. The aBN films grown at 200 °C have the lowest κ value of 1.66 at 100 kHz, along with the breakdown field strength of 5.5 MV/cm. We believe that wafer-level aBN films with various thicknesses can bring new opportunities for the development and application of nanoscale electrical devices.

Optimization of multiple outputs of electric arc spray coating parameters for EN AW 7020-T6

Electric arc spray coating (EASC) is a method used to protect aluminum materials from corrosion, but there is no optimization in the literature using Al99.99 coating wire for EN AW 7020 alloy. The presented study aims to optimize the EASC process parameters (voltage, amperage, spray distance, and number of passes) for EN AW 7020-T6 aluminum samples. The experimental design of selected factors was made with Taguchi L9(34) orthogonal array and the aftermath of optimum values for coating were obtained with the TOPSIS multicriteria decision-making method. Output parameters respectively; pull-off strengths of coating were determined in compliance with the ASTM D4541 standard, the coating thicknesses were measured with a 3D profilometer, and the porosity values for cross-section were analyzed by optical microscope according to ASTM E2109 standard. After determining the optimum parameters, the substrates were coated and the crystallographic analysis of the coated samples was performed by XRD technique and electrochemical corrosion potential values were determined by galvanostat/potentiostat device in 3.5% NaCl solution. In exfoliation corrosion (EXCO) tests performed according to ASTM G34-1 standard, EXCO damage was detected on the surfaces of uncoated samples and graded as EA. In the EXCO tests with coated samples, no corrosion damages were observed on the coatings and they were rated with an N grade. The Al99.99 coating significantly improved the EXCO resistance of EN AW 7020-T6, reducing the corrosion rate by almost 100%. EXCO tests with uncoated and coated samples proved that the Al99.99 coating acts as a barrier to protect the substrate. Optimized Al99.99 coating offers a promising solution to improve the corrosion resistance of EN AW 7020-T6 aluminum alloys and extend their service life in harsh environments.

High corrosion resistance chromium-free passivated copper foils for lithium-ion batteries

Presently, the widely electronic copper foil passivation technology in the field of lithium-ion batteries mostly adopts chromate-containing treatment, but there are serious environmental pollution problems. Here, a novel organic-inorganic chromium-free passivation formula was developed by utilising benzotriazole (BTA), 3-chloropropyltriethoxysilane (CPTES) and taking advantage of the corrosion resistance of nickel. The best passivation formula for corrosion resistance treatment was realised by an orthogonal experiment, consisting of 6 g/L BTA, 5 mL/L CPTES and 6 g/L NiSO4. Through Tafel and impedance tests, the copper foil treated with the passivation solution possesses the most excellent corrosion resistance. The corrosion current density is 1.06 × 10−6 A·cm−2, and the corrosion inhibition efficiency reaches 99.5%. Moreover, the surface of the copper foil transformed from hydrophobicity to hydrophilicity. Surface characterisation through X-ray photoelectron spectroscopy, scanning electron microscope etc . results indicate that BTA, CPTES and Ni in the passivation solution participate in the formation of the passivation film. The chromium-free passivation film has been successfully prepared on the surface of copper foil.

Topography, antisoiling and anticorrosion behavior of the superamphiphobic composite coating on 5083 aluminum alloy based on microarc oxidation

Abstract The inadequate corrosion resistance of aluminum alloys significantly limits their widespread application, thereby necessitating research on enhancing their resistance to corrosion and contamination. Superamphiphobic coatings present a promising solution to mitigate this issue. In this study, spraying technology was employed in conjunction with MAO to create a superamphiphobic composite coating with exceptional corrosion resistance on the surface of 5083 aluminum alloy. The morphology, superamphiphobic characteristics, and corrosion resistance of the material were comprehensively assessed. The corrosion current density of the optimal superamphiphobic composite coating obtained via MAO followed by spraying with modified TiO2 nanoparticles (Icorr = 9.23 × 10-13 A·cm-2) was six and three orders of magnitude lower than that of 5083 aluminum alloy and the unmodified MAO coating, respectively. Furthermore, the coating exhibited a large capacitive arc diameter, enhanced charge-transfer resistance, and high |Z| value at a low frequency (0.01 Hz), signifying its excellent corrosion resistance. Additionally, the coating exhibited superamphiphobic properties with high contact angle (>150°) and low sliding angle (<10°), promoting nonwetting behavior toward various liquids with different surface tensions. This behavior can be attributed to the micro-nanostructure, which significantly enhances surface hydrophobicity and oleophobicity. Moreover, the coating demonstrated dynamic self-cleaning and antisoiling capabilities. These attributes underscored the ability of the coating to exhibit super-repellency, antisoiling performance, ultralow surface energy, and interfacial adhesion forces. Finally, the superamphiphobic composite coating demonstrated noteworthy thermal and chemical stabilities—as evaluated through heat, acid, and alkali resistance tests—thereby affirming its practical viability.

Enabling boosting abrasion resistance of titanium alloy matrix via B4C particles doping micro arc oxidation coating strategy

Abstract Titanium alloy is recognized as the future metal due to its remarkable advantages, including high strength, lightweight properties, and corrosion resistance. Meanwhile, there are a series of technical challenges hindering its development, such as poor abrasion resistance. Herein, we propose a direct strategy by combining micro arc oxidation (MAO) technology with B4C particles doping that can effectively ameliorate the contact mechanics at the interface and regulate the microporous structure of the MAO coating. Exhilaratingly, compared to the titanium alloy and undoped samples, the modified B4C-doped alloy (B0.9) exhibited high hardness of 706.2 HV (increased by 121.9% and 15.8%, respectively) and low friction coefficient of 0.3435 (ameliorated by 40.6% and 39.6%, respectively). Utilizing in X-ray diffraction, scanning electron microscopy, and Image Pro Plus analysis, we found that B0.9 exhibited lower surface porosity and average pore size (8.7% and 3.0 μm, respectively), which are attributed to the regulation of the microporous structure. Specifically, B4C particles are successfully incorporated into the MAO coating by mechanical stirring and electrophoresis, filling the surface micropores and resulting in a denser and more uniform coating. This study emphasizes the compatibility between B4C doping and MAO technology, which effectively provides guidance for the inadequate abrasion resistance of titanium alloy.

Mechanical characterization of sandwich composite structures with Alumix231 foam core between Al2024/B4C composite plates

Abstract The study investigates the production of lightweight B4C particle-reinforced aluminum sandwich foam (ASF) materials, crucial for high impact and corrosion resistance, particularly in defense and automotive sectors. These materials are manufactured via powder metallurgy. Five different combinations of ASF materials, layered and unlayered with B4C, were examined. Alumix231 served as the primary material in the Al foam, with TiH2 as the blowing agent. In layered ASF materials, Al2024 powder acted as the main material, reinforced by B4C particles. Samples with various configurations, including foam, foam/Al2024 layers, and 5-10–20 % B4C particle-reinforced Al2024 layers, were produced. After powder mixing, they were filled into a hot pressing mold, pre-pressed at 25 MPa, dwelled at 550 °C for 30 min, then hot pressed at 200 MPa to form foamable preform material. B4C particle-layered ASF materials were generated by foaming the preforms in a steel mold at 750 °C for 11 min. Microstructure, density, pore size, and morphology analyses were conducted. Al2024 exhibited the highest density at 99 %, decreasing with increased B4C ratio. With more B4C, compressibility decreased, and agglomeration increased. Pores were observed around TiH2 and Si particles in B4C-lacking materials. The material with the best homogeneity and spherical pore resemblance was noted as Alumix231.

Establishment of Multivalent Molybdenum Salt System and Its Effect on the Anti-Corrosion Performance of Insulating Coatings for Oriented Silicon Steel

Chromium salt fillers commonly used in current anti-corrosion coatings are highly toxic. However, due to the unique high–low valence transformation and passivation mechanisms of chromium-based functional fillers and their wide applicability, chromium-free coatings find it challenging to achieve the same performance and industry acceptance. This study introduces an innovative approach that uses zinc to reduce molybdate (MoO42−) in an acidic solution, thereby forming a multivalent MoO42− system (PMZ system), and applies it to chromium-free insulating coating for oriented silicon steel. The effects of reductant dosage on the valence composition of molybdenum in the PMZ system and the corrosion resistance of the coating were investigated. Additionally, the difference in the valence composition of molybdenum between the PMZ system and the multivalent phosphomolybdate system (PMNZ system) and its impact on corrosion resistance were studied. The results indicate that the PMZ system contains trivalent molybdenum and hexavalent molybdenum, while the PMNZ system contains pentavalent molybdenum and hexavalent molybdenum. The systems leverage the reactivity of lower-valence molybdenum to delay the corrosion by reacting with oxygen while maintaining the original mechanism of molybdenum salt fillers and forming sediment with iron ions to form a passivation layer. As the content of trivalent molybdenum in the PMZ system increases, the corrosion resistance of the insulating coating improves. When the amount of zinc added in the PMZ system is 0.006 g, the relative proportion of trivalent molybdenum reaches 20.52%, and the salt spray resistance of the coating developed with the PMZ system reaches 248 h with a corrosion area of less than 5%. When the contents of the main components and sodium molybdate in the PMZ coating and the PMNZ coating are the same, the corrosion resistance of the PMZ coating, which contains trivalent molybdenum, is better than that of the PMNZ coating, and the salt spray resistance exceeds 192 h.