Enhanced Corrosion Resistance Research Articles

Enhanced Corrosion Resistance and Mechanical Durability of the Composite PLGA/CaP/Ti Scaffolds for Orthopedic Implants.

In addressing the challenge of enhancing orthopedic implants, 3D porous calcium phosphate (CaP) coatings on titanium (Ti) substrates modified with poly(lactic-co-glycolic acid) (PLGA) were proposed. CaP coatings on Ti were deposited using the ultrasonic-assisted micro-arc oxidation (UMAO) method, followed by modification with PLGA through a dip coating process at concentrations of 5%, 8%, and 10%. The addition of PLGA significantly improved adhesive-cohesive strength according to the scratch test, while PLGA to CaP adhesion was found to be not less than 8.1 ± 2.2 MPa according to the peel test. Tensile testing showed a typical fracture of CaP coatings and mechanisms of brittle fracture. Corrosion resistance, assessed via gravimetric and electrochemical methods in 0.9% NaCl and PBS solutions, revealed PLGA's substantial reduction in corrosion rates, with the corrosion current decreasing by two orders of magnitude even for the 5% PLGA/CaP/Ti sample. Also, the PLGA layer significantly enhanced the impedance modulus by two orders of magnitude, indicating a robust barrier against corrosion at all PLGA concentrations. Higher PLGA concentrations offered even greater corrosion resistance and improved mechanical properties. This research underscores the potential of using CaP- and PLGA-modified coatings to extend the life and functionality of orthopedic implants, addressing a significant challenge in biomedical engineering.

Enhanced the Electrochemical Stability of Al-Zn-Mg Alloy Through the Dual Incorporation of ZrO2 and V2O5 into the Alumina Layer

This study explores the impact of direct and indirect incorporation of metallic oxide particles namely ZrO2 and V2O5 on the corrosion behavior of the alumina layer obtained by the plasma electrolytic oxidation of Al-Zn-Mg alloy. To achieve this goal, plasma electrolytic oxidation coating was formed in an alkaline-aluminate-ZrO2 electrolyte, without and with NH4VO3. The morphological analysis reveals a porous structure influenced by gas bubble discharge and rapid cooling, featuring micro-pores, oxide nodules, and cracks. The incorporation of V2O5 particles is observed to decrease surface roughness and enhance the compactness of the oxide layer. The X-ray diffraction patterns reveal the presence of γ-Al2O3, α-Al2O3, ZrO2, and V2O5 particles exclusively in the sample coated in the electrolyte with NH4VO3. Potentiodynamic polarization tests in a 3.5 wt.% NaCl solution revealed enhanced corrosion resistance, attributed to reduced micro-defects through V2O5 and ZrO2 incorporation.

Tribological, corrosion, mechanical, and metallurgical behavior of clay and Al2O3-reinforced aluminum-based composite material

Aluminum-based composite materials have garnered considerable attention in recent years owing to their outstanding mechanical and tribological properties. The integration of clay and Al2O3 into the aluminum matrix has notably elevated its tribological, corrosion, mechanical, and metallurgical characteristics. An examination of the metallurgical properties involved a thorough analysis of the material's microstructure and wettability. Notably, the composite material demonstrated enhanced wettability and a more uniformly distributed reinforcement, leading to improved mechanical attributes when incorporating 5% alumina and 5% clay particles. This composition resulted in heightened strength, improved hardness, and increased fatigue strength. Specifically, the addition of a mixture of ball-milled 5% alumina and 5% clay particles led to substantial improvements, with tensile strength, hardness, and fatigue strength increasing by approximately 40.49%, 44.11%, and 62.15%, respectively. However, this enhancement came at the cost of reduced toughness in aluminum, decreasing by about 46.66% following the addition of the ball-milled mixture. Tribological assessments, involving wear tests under varying loads and speeds, demonstrated that the inclusion of 5% clay and 5% Al2O3 substantially improved wear resistance. Furthermore, corrosion resistance was evaluated, revealing that the composite material exhibited enhanced corrosion resistance attributed to the passivation of the surface. Altogether, these findings underscore the promising potential of aluminum-based composite materials for various applications, particularly when tailored with specific ratios of alumina and clay particles.

Correlation between the micro-shot peening coverage and surface microstructural evolution and fluoride-induced corrosion behavior in Monel 400 alloy

This study examines the influence of micro-shot peening (MSP) on Monel 400 alloy, focusing on surface microstructural evolution and fluoride-induced corrosion behavior compared to its solution annealed (SAed) counterpart. MSP treatments were conducted at various surface coverages (100%, 200%, 500%, 1000%, 1500%, and 2000%). Characterization encompassed microhardness, surface roughness, grazing incidence x-ray diffraction (GI-XRD), field emission scanning electron microscopy (FE-SEM) with electron backscatter diffraction (EBSD), and transmission electron microscopy (TEM). With increasing the MSP coverage to 2000%, the surface crystallite size decreased from approximately ∼30 µm in the SAed sample to 60 nm. TEM analysis emphasized dislocation slip and formation of dislocation structures as the primary mechanisms for the grain refinement. However, the 2000% coverage exhibited microcrack formation, compromising its hydrofluoric (HF) corrosion resistance. Electrochemical tests revealed severe localized corrosion in all MSP-treated samples except the 1500% coverage, which exhibited a minimum passive current density of 0.2–1.0 µA/cm2. Inductively coupled plasma optical emission spectroscopy (ICP-OES) of immersion solutions showed lower copper and nickel ion concentrations (<150 ppm) in the 1500% MSP-treated sample, indicating its enhanced corrosion resistance. X-ray photoelectron spectroscopy (XPS) identified NiO, NiF2, CuO, CuF2, and Cu(OH)2 phases in SAed and 1500% MSPed samples, with a higher concentration of copper oxide (CuO) in the corrosion film of the 1500% MSP-treated sample, contributing to its superior corrosion resistance.

Improved corrosion resistance and interfacial conductivity of a-C/(Ti:C)/Ti nano-thin film for 316L stainless steel bipolar plates

To enhance corrosion resistance and electrical conductivity of metallic bipolar plates for proton exchange membrane fuel cells (PEMFCs), the film containing amorphous carbon (a-C) outer layer, titanium carbon compound (Ti:C) transition layer and titanium (Ti) seed layer has been deposited on the surface of 316L stainless steel (316L SS) by multi-arc ion plating method. Dense and uniform a-C/(Ti:C)/Ti nano-thin film is relatively hydrophobic and approximately 300 nm thick, presenting a clear multilayer structure. The interfacial contact resistance of 316L SS is effectively reduced from 124.97 mΩ·cm2 to 3.97 mΩ·cm2 at 1.4 MPa after modification. Electrochemical corrosion tests are investigated in the simulated cathodic PEMFCs environment (0.5 M H2SO4 and 2 ppm HF at 70 ℃ bubbled with air). Potentiodynamic polarization results reveal that the corrosion potential of a-C/(Ti:C)/Ti film modified sample is 0.23 V (vs. Ag/AgCl) and the corrosion current density is only 0.14 μA·cm−2. The durability of the a-C/(Ti:C)/Ti film was assessed by conducting potentiostatic polarization tests at various applied potentials. After 4 h potential of 0.6 V and 0.8 V (vs. Ag/AgCl) holding tests, the current densities of the modified 316L SS have stabilized at 0.076 μA·cm−2 and 0.098 μA·cm−2, respectively.

New insight into the role of Cu addition on surface nanocrystallization and corrosion behavior of aluminum alloy

Realization of surface-reinforced aluminum alloys with excellent corrosion resistance remains a major topic. Herein, a novel method based on combination of electron beam evaporation plating and surface alloying was proposed. Results revealed that the current density is one order of magnitude less than that of the substrate and that the impedance value is doubled. The nanometer-scale refinement of the grains and the homogenous dispersion of nanocrystallization Al2Cu in the modified layer of aluminum alloy contributed to the enhancement of corrosion resistance. This study is expected to provide a new sight for the development of Cu-reinforced high-performance aluminum alloys.

MXene‐CeO2@PDA Synergistically Enhanced Anticorrosion of Waterborne Epoxy Coating

AbstractDeveloping ecofriendly anticorrosion coating has great demand for marine protection. Incorporation of nontoxic inorganic fillers into waterborne epoxy (WEP) coating shows tremendous potential for enhancing corrosion resistance. However, the application of MXene/WEP coating is limited by the poor dispersion of MXene in WEP and insufficient corrosion resistance. Herein, a polydopamine (PDA) modified MXene‐CeO2@PDA (MCP) filler is constructed by a combination of CeO2 with MXene and embedded into WEP to form ecofriendly anticorrosion MCP/WEP coating. Dispersion of MXene in WEP is improved by the introduction of CeO2 and PDA modification. Benefiting from the synergy of the physical labyrinth effect of MXene and the chemical inhibition effect of CeO2, MCP/WEP coating exhibits remarkable anticorrosion behavior in 3.5 wt% NaCl solution with a low corrosion rate (CR) of 4.48 × 10−6 mpy, which is three orders of magnitude lower than that of blank WEP (4.78 × 10−3 mpy). Moreover, MCP/WEP presents long‐term and stable corrosion protection for over 30 days. The results reveal the incorporation of MCP significantly promotes the anticorrosion performance of WEP.

Amino-Modified Graphene Oxide from Kish Graphite for Enhancing Corrosion Resistance of Waterborne Epoxy Coatings.

Waterborne epoxy (WEP) coatings with enhanced corrosion resistance were prepared using graphene oxide (GO) that was obtained from kish graphite, and amino-functionalized graphene oxide (AGO) was modified by 2-aminomalonamide. The structural characteristics of the GO and AGO were analyzed using X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). And the anti-corrosive performance of waterborne epoxy-cased composite coatings with different addition amounts of AGO was investigated using electrochemical measurements, pull-off adhesion tests, and salt spray tests. The results indicate that AGO15/WEP with 0.15 wt.% of AGO has the best anti-corrosive performance, and the lowest frequency impedance modulus increased from 1.03 × 108 to 1.63 × 1010 ohm·cm-2 compared to that of WEP. Furthermore, AGO15/WEP also demonstrates the minimal corrosion products or bubbles in the salt spray test for 200 h, affirming its exceptional long-term corrosion protection capability.

A new index to estimate the corrosion resistance of aluminium‐containing steel

AbstractA new index that estimates the corrosion resistance of aluminium‐containing steel is established and verified. It is based on the well‐known pitting resistance equivalent number (PREN) but accounts for aluminium additions. It is shown that aluminium enhances the corrosion resistance of chromium‐containing steel, with a coefficient of 5.2. The new corrosion resistance index (CRI) is as follows CRI = Cr + 3.3Mo + 16N + 5.2Al. A minimum of 4 wt% of chromium addition is needed. In addition, the atomic ratio of chromium to aluminium addition needs to be higher than 1, for this new index to be valid. This new index allows for simple alloy design guidelines for steel applications that require improved corrosion resistance. Analysis of the data from the literature shows that this index becomes inaccurate when the corrosion environment is in the presence of NaCl, and aluminium becomes less effective in enhancing corrosion resistance.

Corrosion Resistance and Thermal Stability Enhancement of Green Layered Clay/Epoxy Coating

A layered clay/epoxy coating was fabricated to investigate the effects of montmorillonite (MMT) and halloysite nanotube (HNT) loading at 0.5, 1.5, and 2.5 parts per hundred resin (phr) on the corrosion resistance and thermal stability of coated mild steel plates. The corrosion study was carried out by Electrochemical Impedance Spectroscopy (EIS) and Tafel polarization. The |Z|0.1Hz value, Rct, and Rp of the layered/clay epoxy coatings containing 1.5 phr of HNT and MMT exhibited the best anticorrosion performance compared to other clay content levels. The |Z|0.1Hz value for the epoxy coating filled with 1.5 phr of MMT (M1.5) is 2.132 × 109 Ω·cm², while it is slightly higher for H1.5 coatings, i.e., 2.629 × 109 Ω·cm². Water absorption trends were consistent with EIS and Tafel polarization studies. The presence of highly compatible nanocontainers clay reduced the total free volume and promoted cross-linking, enhancing anticorrosion performance. Thermal Gravimetry Analysis (TGA) showed that a 1.5 phr loading of MMT in layered/clay epoxy coating demonstrated better thermal stability than a coating embedded with HNT. This improvement can be attributed to the barrier effect of MMT, which retards the diffusion of oxygen molecules into the coating.

Development of Electrolyte with Enhanced Corrosion Resistance for Sn Electroplating on Multi-Layer Ceramic Capacitors

Capacitors not only store and release electricity but selectively conduct alternating current. Among the various types of capacitors, multi-layer ceramic capacitors (MLCCs) have been widely used in automotive, smartphone, and wearable devices because of their compact size and high capacitance capabilities. In this study, we have developed an electrolyte for tin electroplating on multi-layer ceramic capacitors (MLCCs) to address the barium leaching issue at the termination points of the MLCCs. This issue has been effectively mitigated by introducing NaHSO&lt;sub&gt;4&lt;/sub&gt; into the conventional tin plating electrolyte as a corrosion inhibitor. This addition facilitates a rapid reaction between the dissolved barium ions and NaHSO&lt;sub&gt;4&lt;/sub&gt;, resulting in the formation of a thin passivation layer on the surface of the MLCC. The BaSO&lt;sub&gt;4&lt;/sub&gt; passivation layer effectively prohibits excessive leaching of barium ions from the glass in MLCCs, thereby maintaining chip insulation resistance and preventing crack formation. However, the chemical reaction of NaHSO&lt;sub&gt;4&lt;/sub&gt; and the formation of the passivation layer can lead to the generation of tin hydroxide precipitates due to pH fluctuations. To address this issue, we increase the amount of complexing agent from 100 g/L to 130 g/L. This adjustment enhanced the ability of tin ions to form stronger complexes, thereby enabling stable electrodeposition on the termination of MLCC. Consequently, the final electrolyte for Sn electroplating (denoted as LW-3) simultaneously achieves corrosion resistance and practical working efficiency, resulting in a uniform 5.4 μmthick tin plating layer with outstanding solderability, and high temperature/humidity stability.

Development of targeted chloride-responsive Ag/Ca-MoO4-LDH for synergistic corrosion resistance

Layered double hydroxides (LDHs), as novel corrosion inhibitor in reinforced concrete, face instability in chloride consolidation due to sensitivity to environmental anions. This study explored the use of nano-Ag loaded on MoO4-intercalated CaAl-LDH (Ag/Ca-MoO4-LDH), based on isomorphic substitutes for cement hydration products (AFm), to target and stabilize chloride ion fixation in alkaline environments, thereby enhancing steel corrosion resistance. The mechanism of targeting and the enhancement of corrosion resistance were explored through comprehensive experimental and theoretical analyses. Results showed that Ag/Ca-MoO4-LDH enhanced chloride ion consolidation stability, increased the threshold of chlorides needed to trigger corrosion in simulated chloride-contaminated concrete pore (SCCP) solutions, and boosted steel’s anti-corrosion effectiveness. Unlike direct application methods, Ag/Ca-MoO4-LDH released MoO42− in response to chloride presence, providing superior corrosion prevention. The study elaborated on the stability of Ag+ and Cl− interactions in SCCP solutions, the spontaneous exchange reactions between LDH-MoO4 and both LDH-OH and LDH-Cl, and various anti-corrosion mechanisms, including the formation of protective oxide films on steel surfaces and the precipitation of CaMoO4.

Corrosion Behavior of Chromium Conversion Coated AZ91C Magnesium Alloy in Sodium Borate and Sodium Chloride Aqueous solutions

A chromium containing film was deposited on the surface of the investigated AZ91C magnesium alloy by chemical conversion process. The microstructure and surface morphology of the as- received and coated alloys were initially characterized by optical microscope. The corrosion behavior of AZ91C before and after coating was studied through weight loss technique by immersion in 3.5% NaCl and borate solutions at various concentrations and pH values. Surface corrosion products and passivation films were analyzed by X-ray diffraction. The obtained results showed that AZ91C coated with chromium conversion coating exhibits enhanced corrosion resistance, furthermore X-ray diffraction revealed that corrosion damage was mainly caused by formation of crystalline phase Mg(OH)2. The addition of borate with different concentration enhanced the protection with efficiency of 86% recorded at 0.2N sodium borate concentration and 3.5% NaCl.Corrosion behavior

Heterogeneous nucleation induced A. pernyi/B. mori silk fibroin coatings on AZ31 biometals with enhanced corrosion resistance, adhesion and biocompatibility

Silk fibroin coatings on biomedical magnesium alloys have garnered significant attention due to their enhanced corrosion resistance and biocompatibility. However, the utilization of wild A. pernyi silk fibroin, known for its RGD sequence that facilitates tissue regeneration, presents a challenge for corrosion-resistant coatings on magnesium alloys due to its weak adhesion and high dissolution rate. In this study, we employed hexafluoroisopropanol as a solvent to blend A. pernyi silk fibroin with B. mori silk fibroin. The resulting blended fibroin coating at a 3:7 mass ratio exhibited a heterogeneous nucleation effect, enhancing β-sheet content (32.3 %) and crystallinity (28.6 %). This improved β-sheet promoted the “labyrinth effect” with an Icorr of 2.15 × 10−6 A cm−2, resulting in significantly improved corrosion resistance, which is two orders of magnitude lower than that of pure magnesium alloy. Meanwhile, the increased content of exposed serine in zigzag β-sheet contributes to a higher adhesion strength. Cell cytotoxicity evaluation confirmed the enhanced cell adhesion and bioactivity. This work provides a facile approach for wild A. pernyi silk fibroin coatings on magnesium alloys with enhanced corrosion resistance, adhesion and biocompatibility.

Enhancing corrosion resistance and mechanical properties of laser-direct energy deposited 316 stainless steel via W addition

Additions of 1–5 wt% W element enhanced corrosion resistance and mechanical properties of LDED-316 SS. Microstructure characterized the grain refinement and precipitation of ferrite and W-Mo carbides. Mechanical tests showed enhanced tensile strength and hardness of 316–5 W by 37.4% and 30.8%, respectively. Electrochemical tests indicated an increasing pitting potential and polarization resistance of 316–3 W in 3.5 wt% NaCl solution by 0.535 VSCE and 1679 kΩ·cm2, respectively. Corrosion morphology showed the preferential dissolution of ferrite and W-Mo carbides rather than austenite cell. The change in corrosion processes and presence of WO3 in the passivation film significantly contributed corrosion resistance.

Enhanced corrosion resistance of carbon steel in an aggressive environment by a recently developed pyrazole derivative: Electrochemical, SEM/XPS/AFM, and theoretical investigation

Enhanced corrosion resistance of carbon steel in an aggressive environment by a recently developed pyrazole derivative: Electrochemical, SEM/XPS/AFM, and theoretical investigation

A Novel Coating System Based on Layered Double Hydroxide/HQS Hierarchical Structure for Reliable Protection of Mg Alloy: Electrochemical and Computational Perspectives.

Growing research activity on layered double hydroxide (LDH)-based materials for novel applications has been increasing; however, promoting LDH layer growth and examining its morphologies without resorting to extreme pressure conditions remains a challenge. In the present study, we enhance LDH growth and morphology examination without extreme pressure conditions. By synthesizing Mg-Al LDH directly on plasma electrolytic oxidation (PEO)-treated Mg alloy surfaces and pores at ambient pressure, the direct synthesis was achieved feasibly without autoclave requirements, employing a suitable chelating agent. Additionally, enhancing corrosion resistance involved incorporating electron donor-acceptor compounds into a protective layer, with 8-Hydroxyquinoline-5-sulfonic acid (HQS) that helps in augmenting Mg alloy corrosion resistance through the combination of LDH ion-exchange ability and the organic layer. DFT simulations were used to explain the mutual interactions in the LDH system and provide a theoretical knowledge of the interfacial process at the molecular level.

Influence of ferrum film by FCVA deposition technique on properties of WE43 magnesium alloy

WE43 alloy was successfully coated with ferrum (Fe) films of varying thicknesses using filtered cathode vacuum arc technology. The physical phase composition, surface morphology, corrosion resistance and mechanical properties of the films were extensively investigated. The results demonstrate that a deposition time of 20 min for Fe ions exhibits minimal defects and low surface roughness. Compared to the WE43 substrate, the Fe20 alloy exhibits lower Icorr values at 81 μA/cm2, indicating enhanced corrosion resistance. Immersion experiments further confirm the superior integrity of the Fe20 film compared to other coated alloys tested. Notably, among all deposited modified alloys, Fe20 demonstrates significantly improved mechanical properties with its hardness and elastic modulus being three times higher than those of WE43, providing better wear resistance.

Enhancing corrosion resistance of Al50Ni50 alloy by increasing cooling rate plus annealing

Monophasic Al50Ni50 ribbons were fabricated by melt spinning at circumferential speeds (Sc) of 21 and 42 m/s, and subsequently annealed at various temperatures. The microstructure and corrosion behavior of ribbons were studied through various experimental methods. With increasing Sc, the as-spun and annealed ribbons at 42 m/s show a higher (100) crystal orientation factor F(100), a lower barrier to recrystallization and a higher total film resistance than the counterparts with 21 m/s. The as-spun ribbon at 42 m/s demonstrated a denser and more stable Al2O3 passive film compared to the as-spun and annealed ribbons at 21 m/s. This improvement in passive film can be further enhanced by 700 °C annealing. Therefore, the corrosion resistance of AlNi ribbons can be improved by increasing Sc and additional annealing at an appropriate temperature.

Repassivation-oriented pitting corrosion analysis in a cause-effect relationship with microstructure, precipitation, and mechanical behavior of low-carbon medium-chromium ferritic stainless steel

Ferritic stainless steels (FSS), which are potentially ferromagnetic, play a vital role in electromagnetic applications, including solenoid valves, owing to their ferromagnetic properties. This study delves into the microstructure's impact on the localized pitting corrosion behaviour of cold-drawn (CD) low-carbon medium-chromium ferritic/ferromagnetic EN1.4106. Employing potentiostatic-based corrosion analysis, mechanical assessments, and microstructural evaluations on 44 designated specimens subjected to varied annealing conditions, we unveil a nuanced correlation between corrosion resistance and microstructure. Lower reduction rate of 15% versus 45%, extended-enough annealing conditions, and meticulous microstructural control with average grain size of around 45–46 μm, particularly in minimizing dislocation density alongside the local misorientaion of 15° up to at most 35°, significantly enhance corrosion resistance. Overall, this FSS grade demonstrates commendable non-hardenable characteristics with moderate resistance to pitting corrosion in the two of the most corrosive (acidic and chlorinated) environments. The grade notably passivates in sulfuric acid electrolyte solution (SAES) but undergoes active anodic dissolution in sodium chloride electrolyte solution (SCES), ultimately forming a sort of passive-like oxide layer.