Corrosion Resistance Of Alloy Research Articles

Enhanced Anti-Corrosion and Biological Performance of Plasma-Sprayed Nb/ZrO2/HA Coatings on ZK60 Mg Alloy

Niobium (Nb) and zirconium dioxide (ZrO2) were doped into hydroxyapatite (HA) to fabricate HA-based composite coatings prepared on a ZK60 magnesium alloy by plasma spraying technology to improve anti-corrosion and biocompatibility for clinical applications. The results revealed that the Nb-enriched coating exhibits fewer cracks and pores with a flat surface due to the decreased temperature gradient during spraying, and small needle-like structures can fill the cracks and pores in the ZrO2-contained coating, resulting in a more uniform and dense surface. Compared to coatings with only niobium or zirconium dioxide, the ZrO2/Nb/HA composite coating significantly enhanced the mechanical properties and corrosion resistance of the magnesium alloys. Among all the specimens, the ZrO2/HA coating and ZrO2/Nb/HA coating revealed high surface hardness values (327.73 HV and 293.80 HV, respectively). However, the higher hardness value made the ZrO2/HA coating fragile and more likely to crack, while the ZrO2/Nb/HA coating avoided this shortcoming and exhibited a more comprehensive performance. During immersion tests, the ZrO2/Nb/HA coating exhibited a gradual pH increase and minimal mass loss, and the cytocompatibility test demonstrated promising cellular activity.

Powder bed fusion of solid and permeable Crofer 22 APU parts for applications in chemical process engineering

AbstractAdditive manufacturing of metals has attracted significant attention across various industries. However, its adoption in certain chemical and energy sectors remains constrained by the absence of optimized alloys tailored for high temperatures and corrosive environments. This study explores the laser-based powder bed fusion processing of Crofer 22 APU, a high-temperature, corrosion-resistant alloy ideal for applications such as methane steam reforming reactors, high-temperature fuel cells, and palladium membrane supports. Systematic optimization of laser parameters including laser power, hatch distance, point distance, and building angles was conducted for both dense and porous objects. Dense parts achieved a relative density of 0.9999 and surface roughness of Sa= 41.27±1.48 on a 45$$^\circ$$ ∘ overhang. Porous samples showed a porosity range of 28.655.5% and surface roughness Sa 22.2 $$\upmu$$ μ m to 45.9 $$\upmu$$ μ m as hatch distance increased from 0.12 mm to 0.16 mm. Additionally, an 8YSZ coating applied via screen printing demonstrated the impact of hatch distance and laser power on surface quality. The combination of additive manufacturing of Crofer 22 APU and screen printing of 8YSZ simplifies the preparation of metallic supports for Pd-based membranes, reducing fabrication time and cost by shortening the number of preparation steps. This technique offers a promising approach for scaling up membranes and membrane reactors.

Unveiling the influence of zirconium on the corrosion behavior of Fe-36Ni Invar alloy

The influence of zirconium (Zr) on the corrosion resistance of Fe-36Ni Invar alloy in a 3.5 wt% NaCl solution was systematically investigated. Results indicated that adding Zr promoted the formation of Zr-bearing intermetallic compounds (Ni7Zr2 and Ni2Zr). The phases suppressed the grain growth and numerous dislocations were enriched around the Ni-Zr phases. Unfortunately, the incorporation of Zr into Fe-36Ni Invar alloy impaired corrosion resistance. The marked disparity in Volta potential between the Ni-Zr phases and the matrix signified the existence of micro-galvanic coupling, which caused the matrix to dissolve preferentially. Furthermore, the matrix around the Ni-Zr phases possessed high dislocation density, promoting the emergence of local galvanic corrosion. The introduction of Zr also decreased the protectiveness of the passive film, which was ascribed to the reduction of the thickness of the passive film and the beneficial oxide content in the passive film.

Effect of stage gas nitriding on corrosion and wear resistance of Ti6Al4V alloy in physiological environment

The wear and corrosion resistance of the Ti6Al4V alloy after gas nitriding combined with stage heat treatment was studied in the physiological environment. It was shown that nitriding temperature at the first stage of the heat treatment mainly effects on the surface quality and microhardness of the treated alloy. The corrosion behaviour of the nitrided Ti6Al4V alloy was studied in Ringer's solution, which simulates the physiological environment of human body. It was shown that the corrosion resistance of the alloy is enhanced by increasing thickness and TiN content in the nitride layer, and improving surface quality. The tribological characteristics of the nitrided Ti6Al4V alloy in a tribo-pair with PE-UHMW were evaluated in a 10 % aqueous solution of chondroitin sulfate, which simulates the synovial fluid. It was established that reducing nitriding temperature at the first stage of the heat treatment improved the wear resistance of the treated alloy due to decrease of the surface roughness and microhardness.

Corrosion of Copper, Cupronickel, Nickel Aluminium Bronze and Super-Duplex Stainless Steel Rotating Cylinder Electrodes in Seawater under Turbulent Flow Conditions

The corrosion of uncoated metals in a marine environment restricts the choice of suitable engineering metals and alloys. Anodic dissolution of metal and cathodic reduction of oxygen are important processes and formation of a surface oxide film can affect both electrode reactions. Charge transfer and mass transfer data can provide information on corrosion rate and mechanism. Several metals and alloys having a history of use in marine engineering are considered, including copper, two copper alloys (cupronickel and nickel aluminium bronze) plus a more recent addition to strong, corrosion resistant alloys (a super duplex stainless steel). The rotating cylinder electrode offers the benefits of a controlled, turbulent flow of electrolyte, facilitating controlled mass transfer in a compact cell geometry which is well-suited to bench-top operation. These features are illustrated using a variety of electrochemical techniques, including open-circuit potential vs time monitoring, linear sweep voltammetry, rotation speed step- or potential step current transients and linear polarisation resistance measurements. Seawater taken from Langstone Harbour, Hampshire, UK, was filtered, air-saturated, pH 8.0 and maintained at 25 °C. Dimensionless group correlations and graphical plots (using an analogous approach to the Koutecky-Levich equation for an RDE) enabled contributions of charge transfer-, mixed- and mass transfer- controlled data to be appreciated, allowing the Tafel slopes of electrode reactions, the diffusion coefficient of dissolved oxygen, the mass transfer coefficient for oxygen reduction and the mean corrosion rate to be estimated.

Comprehensive evaluation of corrosion resistance and biocompatibility of ultrafine-grained TiMoNb alloy for dental implants

To address the limited wear resistance observed in traditional titanium alloys, we have developed an ultrafine-grained equiatomic TiMoNb compositionally complex alloy (CCA) with exceptional wear resistance. However, there is a significant lack of in vitro and in vivo evaluation of the TiMoNb CCA for biomedical applications. In this study, we comprehensively evaluate the corrosion behavior, tribo-corrosion performance, biocompatibility, and osseointegration of the TiMoNb alloy. Our findings indicate that the alloy exhibits strong corrosion resistance and stable tribo-corrosion behavior, attributed to the presence of Ti-rich nanoscale precipitates that impede tribo-corrosion-induced shear deformation, along with a protective nanoscale oxide layer. Furthermore, in vitro and in vivo evaluations demonstrate the excellent biocompatibility of the TiMoNb alloy and reveal its ability to promote the regeneration of defective femurs and its favorable bone osseointegration capability. Overall, our study underscores the potential of the TiMoNb alloy as a promising material for dental implants and provides valuable insights into the tribo-corrosion mechanisms of ultrafine-grained alloys.

Corrosion behavior of novel Ti6422 alloy with equiaxed structure and lamellar structure in HCl solution

This study systematically investigated the electrochemical corrosion and static immersion corrosion behavior of the novel Ti6422 (Ti-6Al-4V-2Mo-2Fe) alloy with equiaxed (EM) and lamellar structure (LM) in HCl solution. The differences in corrosion performance between EM and LM samples were analyzed based on the characteristics of the passive film and substrate microstructure. Results indicated that the LM sample contained higher contents of TiO₂, Al₂O₃, and MoO₃ with higher stability compared with the EM sample, and the thickness of passive film was approximately twice that of the EM sample. Additionally, the donor density of LM sample was lower than EM sample. These findings indicate that the passive film on LM samples is thicker, with fewer defects and higher density. Electrochemical corrosion results revealed that the corrosion current of LM samples was lower and the polarization resistance was higher than these of EM samples, both suggesting superior corrosion resistance of LM samples. Immersion corrosion further confirmed that the LM sample had a lower corrosion rate. The enhanced corrosion resistance in LM samples was primarily due to higher content of corrosion-resistant β phase. Conversely, the numerous micro-galvanic cells between αs precipitates and adjacent β phase in EM samples weakened the corrosion resistance. Overall, these results demonstrated that regulating microstructure through heat treatment is an effective strategy for improving corrosion resistance of titanium alloys.

تأثير استعمال ليزر النيوديميوم ياك (Nd-YAG) على البنية الدقيقة وصلابة سطح الفولاذ AISI1012

The unique characteristics of the laser beam such as directionality, monochromaticity, and brightness make it a very important tool in the surface treatment engineering. The concentrated heat in the laser beam can be precisely directed toward the processed region on the surface. The laser beam power, beam size, and scanning velocity are easily controlled during the different processing methods. Laser surface modifications of metallic materials, such as laser surface melting, laser surface alloying, and laser cladding are some of the most important methods to improve the mechanical properties of the processed layer on the surface. A pulsed Nd-YAG laser surface melted specimens of low carbon steel with a maximum power of 90W at different processing parameters. The rapid melt and solidification of the treated layer produced a refinement in the microstructure. The original microstructure of this steel (Ferrite + Pearlite) has been transformed to new phases of martensitic and bainitic structures. The melted layer consists of the melted pool, the heat affected zone, and the substrate. The maximum hardness of the laser melted layer is more than 400 HV. The effect of different lasers such as high power CW CO2 laser on the mechanical properties and corrosion resistance of steel alloys will be carried out in future studies. Keywords: Nd-Yag Laser, Laser surface treatment, Microstructure and hardness of AISI1012 steel

On the corrosion resistance of the CoCrFeMnNi high entropy alloys in chloride-containing sulfuric acid solutions

The electrochemical reactivity of the high entropy Cantor alloy (CoCrFeMnNi) was investigated via potentiodynamic polarization curves, electrochemical impedance spectroscopy (EIS), and surface analysis as a function of chloride content, in sulfuric acid solutions. The results revealed that corrosion mechanism of the CoCrFeMnNi alloy at the corrosion potential, is a two-step mechanism, involving one adsorbed intermediate, similar to that of pure iron in the H2SO4, and this model provided a good description of the impedance data. X-ray photoelectron spectroscopy (XPS) surface characterization and impedance data fitting revealed that chloride ions do not alter the corrosion mechanism or the thickness of the surface oxide film. Instead, they affect the corrosion resistance by changing the composition of the oxide film. Additionally, this work demonstrated that the corrosion mechanism of the CoCrFeMnNi alloy varies with the applied potential, as evidenced by impedance measurements under potentiostatic polarization. Surface observations using scanning electron microscopy (SEM) and XPS analysis provided insights into the morphology and composition of the surface oxide film at different applied potentials, explaining the observed changes in impedance.

Superhydrophobic carbon fiber composite coatings based on TC4 titanium alloy for improving corrosion resistance

Seawater corrosion poses significant challenges to marine industrial equipment, leading to a reduced lifespan and potential safety hazards. To enhance the corrosion resistance and reliability of titanium alloys in marine environments, a superhydrophobic TiO₂ nanotube-carbon fiber composite coating (SCF-TAD20) was developed through anodic oxidation, spraying, and chemical modification. SCF-TAD20 achieves a contact angle of 153°, which facilitates excellent corrosion protection due to its unique micro-nano structure, gas barrier properties, and chemical resistance. Electrochemical tests demonstrate that SCF-TAD20 increases the corrosion potential from -0.482 V to 0.0612 V and reduces the corrosion current density from 377.8 × 10-8 A/cm2 to 0.615 × 10-8 A/cm2, a four-order decrease. Its charge transfer resistance (∼8.81E6 Ω·cm2) is significantly higher than that of the substrate (∼3.03E5 Ω·cm2). The coating also performs well in seawater with varying pH levels, showing the lowest corrosion current density and a significant increase in resistive arc radius. This research presents a novel approach to enhancing TC4 titanium alloys for marine applications.

Enhancing aesthetics, hardness and corrosion resistance of aluminum alloy via deposition of Al/Si/AlN coatings

Enhancing aesthetics, hardness and corrosion resistance of aluminum alloy via deposition of Al/Si/AlN coatings

Construction and biocompatibility evaluation of CS-FA/VA composite coating on the surface of ZE21B vascular stent

Magnesium alloys have become the focus of attention as a new generation of vascular stent materials due to their excellent mechanical properties and degradability. However, their rapid degradation rate and poor surface endothelialization performance have become key factors limiting their clinical application. In this study, the Mg-Zn-Y-Nd (ZE21B) surface was modified with the magnesium fluoride (MgF2) corrosion-resistant layer, and the polydopamine (PDA) layer was used to immobilize the chitosan (CS)-ferulic acid (FA)/vanillic acid (VA) bioactive composite coating. The results of the electrochemical and hydrogen evolution experiments showed that the corrosion current density and hydrogen release of the modified ZE21B alloy significantly decreased, and its corrosion resistance was enhanced; the results of the hemolysis rate and whole blood experiments showed that the adhesion of blood components such as white blood cells and platelets on the surface of the modified ZE21B alloy significantly decreased, improving the blood compatibility of the magnesium alloy; the results of in vitro cell experiments showed that the modified ZE21B alloy effectively promoted endothelial cell (ECs) adhesion and proliferation, and inhibited smooth muscle cell (SMCs) pathological proliferation. These enhancements suggest that the CS-FA/VA coating significantly improves both the corrosion resistance and biological compatibility of the ZE21B alloy.

The influence of nitrogen content on the microstructure and properties of W-Ta-Cr-V-N refractory high-entropy nitrides

To enhance the mechanical performance and corrosion resistance of refractory high-entropy alloys (RHEAs) and to identify materials better suited for severe high-temperature and corrosive environments, this study utilized a double glow plasma surface alloying technique to fabricate a W-Ta-Cr-V-N refractory high-entropy nitride coating on a W substrate. The microstructure and phase structure of the samples were characterized using a scanning electron microscope and X-ray diffractometer. The mechanical properties of the samples were evaluated through microhardness testing, while their corrosion performance was assessed by potentiodynamic polarization and electrochemical impedance spectroscopy measurements. The study investigated the effects of different nitrogen contents on the microstructure, mechanical properties, and corrosion resistance of the BCC-structured W-Ta-Cr-V alloy in the past tense. The study found that the doping of an appropriate amount of nitrogen can lead to the formation of FCC and HCP structured nitrides. As the nitrogen content increases, there is a significant change in the preferred orientation of the coating. When the nitrogen content is 16.6 at.%, the distribution of the nitrides is uneven, resulting in increased surface undulations and roughness. Conversely, when the nitrogen content is elevated to 48.1 at.%, the clustering of surface nitride particles becomes more pronounced, leading to a decrease in the coating density. The thickness of the nitride coatings is around 10 μm, with a slight decrease in thickness as the nitrogen content increases. The hardness of the coatings is significantly superior to that of the W-Ta-Cr-V alloy films, reaching up to 3465 HV0.25 in the highest instance. The introduction of 31.4 at.% nitrogen results in the densest coating, effectively enhancing the corrosion resistance of the refractory high-entropy alloy. Therefore, the doping of an appropriate amount of nitrogen can alter the microstructure of the refractory high-entropy alloy, improve its mechanical properties, and enhance its chemical stability.

The effects of ECAP, Mn and Ca elements on the microstructure and corrosion properties of magnesium alloys were investigated

In this study, through reasonable composition design, three elements of Zn, Mn and Ca, which are harmless to human body, were selected for alloying magnesium. The effects of ECAP treatment on the microstructure and corrosion properties of Mg-4Zn-1Mn-0Ca, Mg-4Zn-1Mn-0.2Ca and Mg-4Zn-0Mn-0.2Ca alloys were studied. The corrosion mechanism of Mg-Zn-Mn-Ca alloys with different components in Simulated. Body fluid (SBF) was analyzed by weight loss method and electrochemical test. The grains and the second phase were refined by Equal Angular Channel Pressing (ECAP). It was found that after 8 ECAP deformations, the microstructure of the alloy was refined and more uniform than that of the extruded alloy. The corrosion resistance of the Mg-Zn-Mn-Ca alloy after ECAP deformation in simulated body fluids was studied by electrochemical testing techniques, immersion experiments and observation of the microstructure and morphology of corrosion products. The relationship between microstructure characteristics, the behavior of the magnesium metal matrix and the properties of corrosion products was revealed. The results show that the microstructure of the alloy is refined and the corrosion resistance is improved with the increase in extrusion passes in the SBF solution. The corrosion resistance of magnesium alloy after 8 ECAP deformation is the best, showing small Icorr and large Rt. With the extension of the soaking time, the surface of the alloy will form a passivation film, which will protect the matrix and avoid further corrosion of the alloy. It is found that in SBF, the corrosion of the alloy surface is mainly pitting, which indicates that Ca2+, HCO3- and HPO42- in SBF can reduce the corrosion rate of magnesium alloy.

Microstructure and localized corrosion properties of 2219 aluminum alloy manufactured by additive friction stir deposition

Multi-layer 2219 aluminum alloy samples were successfully fabricated using additive friction stir deposition (AFSD). AFSD deposition reduced grain size and the size of intermetallic Al2Cu particles, but greatly increased the amount of Al2Cu particles. More Al2Cu particles increased the number of galvanic microcells on alloy surface and at the grain boundaries, which promoted the localized corrosion and improved the intergranular corrosion sensitivity of AFSD alloy. Subsequent T6 heat treatment had little effect on grain size but enhanced the corrosion resistance of AFSD alloy, primarily attributed to the reduction in Al2Cu particles and the elimination of dislocations within grains.

Enhancing corrosion resistance of T91 F/M steel in liquid lead-bismuth (LBE) by slurry FeAl coating

A FeAl coating was fabricated on T91 steel via slurry aluminizing. The corrosion behavior of coated and uncoated samples was assessed in static LBE (lead-bismuth eutectic) with two both high and low dissolved oxygen concentrations at 550 °C. The coating was mostly intact and exhibited great corrosion resistance compared to the uncoated specimens regardless of the oxygen concentration. That is because the coating can form a protective alumina film on the surface at extremely low dissolved oxygen level. This coating is of significant engineering value in enhancing the corrosion resistance of Fe base alloy in LBE.

PDA-modified sol-gel coating for long-lasting corrosion protection on Al alloy 3003

Within the realm of corrosion protection methods for Al alloys, sol-gel technique has garnered increasing attention. However, conventional sol-gel methodologies cannot provide adequate long-lasting corrosion protection to Al alloys when exposed to chloride-rich solutions. This paper introduces an innovative approach to substantially augment the corrosion resistance of aluminum alloys through utilization of polydopamine (PDA)-modified sol-gel films. Effort was made to fabricate a PDA-modified sol-gel coating and a systematic investigation was conducted thereof. Long-term corrosion performance of this coating in 3.5 wt.% NaCl solution was evaluated through electrochemical impedance spectroscopy (EIS). Results show that the low-frequency impedance of the PDA-modified sol-gel coating remains significantly high at 7.9 × 105 Ω·cm2, even after 36 d of immersion in 3.5 wt.% NaCl medium, indicative of excellent protective properties. It notably surpasses low-frequency impedance of the unmodified coating, which registers at 2.5 × 104 Ω·cm2. The incorporation of PDA into the sol-gel coating, facilitated by adsorption and diffusion mechanisms, serves to fill micrometer- and nanometer-scale defects of the coating, thereby markedly enhancing their compactness. Furthermore, despite its modest thickness of 9 μm, the PDA-modified coating exhibits enduring corrosion protection capabilities.

Enhanced wear resistance, corrosion behavior, and thermal management in magnesium alloys with PEO coatings

The harsh conditions encountered in aerospace applications, such as high operational temperatures, abrasive wear, and corrosive substances, present significant challenges to the performance and longevity of magnesium alloy components. To create a coating with superior wear resistance, corrosion resistance, and high emissivity, this study employs plasma electrolytic oxidation (PEO) technology to develop a nanocomposite coating doped with carbon nanotubes (CNTs) and hexagonal boron nitride (h-BN). The results demonstrate that the MgO-BN/CNTs coating with an emissivity of 0.82 reduces the equilibrium temperature of the 5 W LED junction by nearly 10 °C compared to the magnesium alloy substrate, showing improved radiative heat dissipation performance. Due to the ability of the porous structure to accommodate abrasive particles, coupled with the lubricating effect of h-BN and CNTs, the friction coefficient of the MgO-BN/CNTs coating is 0.57, which is 21 % lower than that of the MgO coating. Additionally, the coating exhibits excellent corrosion protection, attributed to the dense microstructure and chemical inertness of h-BN. The findings demonstrate that the strategic incorporation of h-BN and CNTs into PEO coatings effectively improves the wear resistance, corrosion resistance, and thermal management performance of magnesium alloys.

A novel corrosion resistant NiFeCrAlTi eutectic high entropy alloy with high strength and ductility

We present a novel corrosion resistant Ni42.6Fe24.6Cr16.4Al13.4Ti3 eutectic high entropy alloy (EHEA), which consists of FCC(L12) phase and BCC(L21) phase. The FCC and BCC phases contain numerous nano-precipitates, with sizes of ∼10 nm and 80 nm, respectively. The as-cast EHEA exhibits exceptional mechanical properties with a yield strength of ∼730 MPa, an ultimate tensile strength of 1220 MPa and elongation of 25 %, surpassing those observed in other as-cast EHEAs. The excellent mechanical properties are attributed to the extensive dislocation activities and precipitation strengthening in both BCC and FCC phases, as well as hetero-deformation induced (HDI) strengthening. Besides, the Kurdjumov-Sachs (KS) orientation relationship between adjacent phases promotes the cooperative deformation of both constituent phases, thereby enhancing the ductility of the EHEA.

Optimization of Welding Process for 825 Bimetallic Composite Pipes Based on Corrosion Testing

Abstract In the process of welding bimetallic composite pipe ring joints, a problem arises where the outer layer of carbon steel dilutes the inner corrosion-resistant alloy lining, resulting in a reduction in corrosion resistance. Therefore, selecting the appropriate welding process and parameters is crucial. This study established manual, semi-automatic, and fully automatic welding processes for welding 825 bimetallic composite pipes, conducted simulated corrosion tests on weld joint ring seams under sulfur-containing conditions, and performed comprehensive evaluations of physical and chemical properties, as well as corrosion resistance. The research findings are as follows: (1) There is a phenomenon of softening in the heat-affected zone of bimetallic composite pipe ring seams. Among them, the fully automatic welding method exhibits significant fluctuations in weld joint strength, higher toughness in the weld and heat-affected zone, and higher hardness values with less variation compared to other welding methods. (2) Under the manual, semi-automatic, and automatic welding processes, the intergranular corrosion rates are 1.08 mm/a, 1.64 mm/a, and 1.11 mm/a, respectively, and the pitting corrosion rates are 0.41 g/m2, 0.25 g/m2, and 0.31 g/m2, respectively. The uniform corrosion rates are 0.0002305 mm/a, 0.0002183 mm/a, and 0.0002197 mm/a, respectively. (3) High-temperature solution heat treatment (above 980 ° C for 30 minutes) can effectively promote the dissolution of carbides into the matrix, improving the intergranular corrosion resistance of alloy 825. The research demonstrates that under sulfur-containing conditions, weld joints obtained using the fully automatic welding process developed in this study exhibit better physical characteristics and corrosion resistance. This can effectively prevent corrosion failures and leakage incidents.