Corrosion Resistance In Seawater Research Articles

An imine-functionalized silicone-based epoxy coating with stable adhesion and controllable degradation for enhanced marine antifouling and anticorrosion properties.

Biofouling and corrosion of submerged equipment caused by marine organisms severely restrict the rapid development of the marine industry. Traditional antifouling or anticorrosion coatings typically serve a sole purpose and exhibit limited degradability upon failure, rendering them inadequate for current demands. Herein, a novel imine-functionalized command-degradable bio-based epoxy coating (SAHPEP-DDM) with enhanced integrated antifouling and anticorrosion performances was synthesized utilizing 1,3-bis (3-aminopropyl)-1,1,3,3-tetramethyldisiloxane and syringaldehyde. Compared with commercial epoxy resins (E51-DDM) and polydimethylsiloxanes (PDMS), the SAHPEP-DDM coating exhibits superior antifouling and anticorrosion properties due to the existence of -C=N- and Si-O-Si chain segments in the cross-linking network. The coatingshows promising resistance against bacteria, algae and proteins, as well as excellent corrosion resistance in artificial seawater. The coating also exhibits excellent chemical resistance in organic solvents as well as neutral and alkaline environments. Moreover, its controlled degradation afterfailure can be achieved in acid aqueous solutions through temperature and acidity adjustments, facilitated by the presence of -C=N-. This work presents a novel degradable coating successfully coupled the dual functions of antifouling and anticorrosion coatings, avoiding the employment of intermediate coat, indicating vast potential for application inmarine engineering fields.

(La0.2Ce0.2Gd0.2Er0.2Sm0.2)2Zr2O7 High-entropy ceramic-glass composite coating with a high corrosion resistance

In this work, a new type of high-entropy ceramic powder (La0.2Ce0.2Gd0.2Er0.2Sm0.2)2Zr2O7 was synthesized by sol-gel method and high-temperature sintering (1000 °C) method. Combing (La0.2Ce0.2Gd0.2Er0.2Sm0.2)2Zr2O7 and glass powder to prepare high-entropy ceramic-glass composite coating. The composite coating exhibits excellent seawater corrosion resistance and high-temperature resistance performance. The impedance values of composite coating are 2.36 × 106 Ω cm2 in 3.5% NaCl solution for 24 h. The high-entropy ceramic-glass composite coating could withstand the high temperature of 600 °C for 30 days and remains tight and intact with stainless steel without falling out. This work shows that the (La0.2Ce0.2Gd0.2Er0.2Sm0.2)2Zr2O7-glass composite coating can provide long-term high-temperature and seawater corrosion protection for stainless steel and has good application prospects in the field of marine corrosion protection.

Laboratory investigation on static and dynamic properties, durability, and microscopic structure of Nano-SiO2 and polypropylene fiber cemented soil under coupled seawater corrosion and cyclic loading

Cemented soils in coastal harbors are susceptible to adverse factors such as seawater corrosion and cyclic dynamic loading, which may consequently reduce their stability and durability. In recent years, Nano-SiO2(NS) has been widely used to enhance the mechanical properties of cemented soil. However, this enhancement may potentially lead to a reduction in ductility. Conversely, polypropylene fibers (PP) have attracted widespread attention for their potential to enhance the ductility of cemented soils, but their ability to improve the strength of cemented soils is limited. To address these issues, this study focused on utilizing five different nano-dosages combined with four different fiber dosages to enhance cemented soils. These enhanced soils were then subjected to curing periods of 7, 28, and 60 days in seawater environments. The study employed various tests including unconfined compressive strength tests (UCS), uniaxial cyclic loading tests, scanning electron microscopy tests (SEM), X-ray diffraction (XRD), and nuclear magnetic resonance (NMR) to investigate the potential impacts of these additives on durability, strength, corrosion resistance, and microstructure evolution. The results of the study indicate that seawater corrosion and cyclic loading contribute to a reduction in the stability of cemented soils. However, the addition of NS and PP effectively enhances the compressive strength and durability of these soils. The optimal combination ratio is achieved when the dosages of NS and PP are 3.6 % and 0.8 %, respectively. In this case, the growth rate of unconfined compressive strength of cemented soils surpasses the sum of each individual dosage, increasing by 137.7 %, 245.6 %, and 235.3 % after 7, 28, and 60 days of curing, respectively. Furthermore, the growth rate of PP on the compressive strength of cemented soils remains largely unaffected by seawater corrosion. The optimal composite dosage of cemented soils effectively mitigates the increase in porosity caused by seawater corrosion. C-S-H enhances the mechanical interlocking between hydration products and PP by encapsulating PP, reducing energy transfer losses in cemented soils, and increasing their dynamic modulus. The volcanic ash reaction and nucleation effect of NS further enhance this effect, and their combined use significantly improves the seawater corrosion resistance of cemented soils.

Cu-mediated electron-rich Ru centers on metal carbides for highly efficient hydrogen production from seawater

Seawater splitting for hydrogen production provides a promising pathway for green energy systems. However, the sluggish kinetics, corrosive ions, and the calcareous deposit seriously impede the wide-scale application of seawater electrolysis. Here, we report a trace amount of Cu-mediated anchoring electron-rich Ru centers on metal carbides (Cu-Ru/WC@C) for efficient hydrogen evolution from corrosive seawater. Benefiting from the conductive, electron-loss, and protophilic capacities of Cu atoms, the created Cu-Ru/WC@C catalyst possesses an electron-rich, anti-corrosive, and low oxophilic microenvironments, which eventually delivers excellent hydrogen evolution activities and anti-corrosion properties in seawater electrolysis. It requires a low overpotential of 392 mV to reach 1 A cm−2 and good long-term stability in alkaline seawater. Notably, the membrane electrolyzer with Cu-Ru/WC@C cathode exhibits outstanding performances for continuous H2 production under 1.875 V with 250 mA cm−2. This approach provides essential insights into the seawater corrosion resistance for cathode materials that match the electrochemical hydrogen production industry.

Monitoring and Evaluation of the Corrosion Behavior in Seawater of the Low-Alloy Steels BVDH36 and LRAH36.

The purpose of this study is to evaluate the corrosion resistance in natural seawater (Năvodari area) of two types of low-alloy carbon steels BVDH36 and LRAH36 by electrochemical methods. The electrochemical methods used were the evolution of the free potential (OCP), electrochemical impedance spectroscopy (EIS), polarization resistance (Rp) and corrosion rate (Vcorr), potentiodynamic polarization (PD), and cyclic voltammetry (CV). The studies were completed by ex situ characterization analyzes of the studied surfaces before and after corrosion such as: optical microscopy, scanning electron microscopy and X-ray diffraction analysis. The results of the study show us that the polarization resistance of the low-alloy carbon steel BVDH36 is higher compared to the polarization resistance of the low-alloy carbon steel LRAH36. It is also observed that with the increase in the immersion time of the samples in natural seawater, the polarization resistance of the BVDH36 alloy increases over time and finally decreases, and for the carbon steel LRAH36 the polarization resistance increases.

Study on seawater corrosion resistance of copper alloy

Abstract The Marine environment is a very complex and corrosive environment. Marine corrosion environment can be generally divided into Marine atmospheric environment and seawater environment. Because the seawater is rich in a variety of free ions mixed with corrosive media, the main component is sodium chloride, in addition to containing magnesium, potassium, iodine, bromine, and other elements of salt, which has strong corrosion to metal materials, if serious, it will cause safety accidents. Therefore, ensuring the effectiveness of the anticorrosion system is very important for the safe and reliable operation of the offshore platform. pulse plating is used and the metal nickel coating and metal nickel-chromium coating are prepared to analyze the microstructure and corrosion resistance of each film layer. From the macroscopic, it can be found that three coatings have more or less corrosion phenomenon, there is obviously no nickel-chromium and nickel layer on the surface of nickel-chromium corrosion defects, and through scanning electron microscopic observation, microscopic level nickel chromium corrosion after corrosion phenomenon is the least of three layers, which suggests that nickel chromium seawater corrosion resistance is strong. The three layers are then electrochemical corroded to study the corrosion resistance of the three layers. The results show that the corrosion resistance of the nickel-plated layer, nickel-chromium coating, and nickel-iron chromium coating prepared in the copper substrate is improved successively, which shows the influence of different membrane elements on the corrosion resistance of copper substrate against seawater medium. Although the composition parameters of the various membrane layers vary, they experience the same corrosion mechanism-pitting; Nickel chromium and chromium, iron and other atoms are present in the nickel matrix in the form of solid solution and finally form the solid solution alloy coating. For nickel-chromium coating, the content of iron and chromium in the surface layer has a certain influence on the corrosion resistance of the metal coating. The electrochemical parameters of nickel plating are studied separately, and the comparison with the nickel-chromium alloy coating and the coating is conducted. The equivalent circuit is fitted and determines the largest impedance value and the largest phase Angle among the three membrane layers, which finally has the strongest seawater corrosion resistance.

Robust and efficient Iron-Based electrodes for hydrogen production from seawater at high current density above 1000 mA cm−2

The implementation of cheap iron-based catalysts for seawater electrolysis at high- current–density offers an economical and sustainable solution for industrial hydrogen production in near future. However, Fe-based electrodes suffer from poor intrinsic activity and corrosion resistance in seawater, resulting in unsatisfactory seawater splitting performance. Here, we reported the scale-up fabrication of whole-Fe-based electrodes (NiFe-X (X = O, P) NAs/Fe foam) by facile soaking-phosphating. Surface active layers exhibit enhanced corrosion resistance compared to bare Fe foam, and trace Ni modification lowers reaction energy barriers of cathodic NiFeP and in-situ generated anodic NiFeOOH, respectively. Thus, NiFe-P||NiFe-O pair only requires 1.93 V to deliver 3000 mA cm−2 at 6 M KOH, 60 °C for overall seawater splitting, and works stably for 200 h at 1000 mA cm−2. Furthermore, NiFe-X (X = O, P) NAs/Fe foam show impressive adaptation to fresh water/tap water/seawater and all kinds of renewable energies, presenting excellent flexibility for various environmental applications and scenarios.

Study on seawater corrosion resistance of calcium sulfoaluminate cement-based novel grouting materials

Grouting materials play a critical role in anchoring structures of cross-sea tunnels by safeguarding the anchors against seawater corrosion and enhancing durability. In this paper, a novel grouting material comprising ferrite-rich sulfoaluminate cement (FCSA), ordinary Portland cement (OPC), anhydrite and limestone were prepared. Accelerated corrosion immersion tests were conducted to assess the corrosion resistance of the grouting material using artificial seawater solutions with varying salt concentrations. Pull-out tests were performed to verify the material's performance, while potentiometric titration and X-ray diffraction (XRD) analysis were employed to analyze free chloride ion concentration (Cf) and corrosion products at the anchorage interface. Results indicate that after 1.5 years of corrosion in seawater with different salt concentrations, the bond strength stabilized at 1.05 MPa. No rust was observed on the anchor surfaces and the Cf exhibited a linear increase with salt concentration. The content of Friedel's salt increases with salt concentration, demonstrating adequate chloride ion binding capacity. The test results validate the exceptional seawater corrosion resistance and long-term stability of the novel grouting material.

Bifunctional Mo4O11 Nanosheets-Engineered Co-Ni alloy nanowires enable High-Efficiency seawater electrolysis and Zn-Seawater battery

This study reports an electrocatalyst derived from multi-valent Mo4O11 nanosheets coupled Co-Ni (CN) nanowires (NW) (denoted as CN@Mo4O11) with improved catalytic coherency for both high-performance seawater splitting and Zn-seawater battery. The CN@Mo4O11 material significantly enhances the catalytical activity with a low overpotential of 63 mV/69 mV for hydrogen evolution and 100 mV/120 mV for oxygen evolution, respectively, to attain 10 mA⋅cm−2 in alkaline freshwater/seawater. An electrolyzer cell of CN@Mo4O11(+,-) exhibits a low cell voltage of 1.40 V/1.44 V at 10 mA‧cm−2 during alkaline freshwater/seawater splitting with an excellent performance retention of 98.6 %/97.6 % after a long-term operation for 50 h. The solar cell coupled electrolyzer also delivers a high solar to hydrogen conversion efficiency of 15.54 %/16.1 % in alkaline freshwater/seawater. A Zn-seawater battery based on CN@Mo4O11 cathode also delivers high current and power densities of 82 mA‧cm−2 and 27.6 mW‧cm−2, respectively, with a stable discharge time of 40 h. The CN@Mo4O11 heterostructure imparts favorable density of states and optimized adsorption energy for HER and OER, as deduced from DFT calculations, leading to improved overall catalytic performance and corrosion resistance in seawater. Results of this work clearly prove that this proposed catalyst architecture indeed has a huge potential for both seawater splitting and Zn-seawater battery fabrication.

Effects of Passivation with Cu and W on the Corrosion Properties of Super Duplex Stainless Steel PRE 42

Carbon steel is subjected to several pretreatments to enable its use in highly corrosive environments, such as marine structures. However, its surface treatment is problematic owing to various processes, and these problems can be solved by replacing it with super duplex stainless steel (SDSS), which exhibits remarkable strength and corrosion resistance owing to its austenite and ferrite phases. EN 1.4410 and EN 1.4501 are the most extensively used SDSS grades in marine structures, as they exhibit exceptional strength and corrosion resistance in seawater. This study subjected EN 1.4410 and EN 1.4501 samples to specific heat treatment after casting and observed their structural alterations through field emission scanning electron microscopy. Their passivation states, with or without the Cu and W layers, were determined by examining their corrosion properties through open-circuit potential measurements, electrostatic polarisation tests, electrochemical impedance spectroscopy (EIS), and critical pitting temperature (CPT) analysis. The inclusion of Cu significantly improved the uniform corrosion resistance within the passivation layers, whereas the addition of W enhanced the pitting resistance (Epit, CPT). Additionally, the EIS analysis confirmed a double-layer structure in the passivation layer of EN 1.4501. Moreover, Cu did not act as a strengthening element of the passivation layer, whereas W significantly reinforced it.

High-Throughput Designed and Laser-Etched NiFeCrVTi High-Entropy Alloys with High Catalytic Activities and Corrosion Resistance for Hydrogen Evolution in Seawater.

Electrocatalytic hydrogen evolution from seawater through wind or solar energy is a cost-effective way to produce green hydrogen fuel. However, the lack of highly active and anti-corrosive electrocatalysts in seawater severely hinders the industrial application. Herein, a novel Ni1.1FeCr0.4V0.3Ti0.3 high-entropy alloy (HEA) is designed through high throughput computing and prepared via powder metallurgy with the surface treated by laser etching under different laser power. The laser-etched NiFeCrVTi high-entropy alloys exhibit a unique periodically ordered structure with multiple active centers and high porosity. The Ni-HEA-30 displays remarkable hydrogen evolution reaction (HER) performance with an overpotential of 55.9mV and a Tafel slope of 47.3mV dec-1 in seawater. Density functional theory (DFT) calculations are applied to identify the real active sites for HER on the HEA surface as the key factor for both proton and intermediate transformation, which also reveals that the Cr atom promotes the adsorption energy of water molecules, and the modulation of the electronic structure plays a crucial role in optimizing the hydrogen binding capabilities of the Ni atoms within the alloy. Additionally, the electrocatalyst displays high corrosion resistance in seawater, contributing to the good durability for hydrogen production. This work uncovers a new paradigm to develop novel electrocatalysts with superior reaction activity in seawater.

Improving corrosion and wear resistances of 2195 Al–Li alloy by PEO and LDHs composite coating

In this study, a composite coating comprising a ceramic film and layered double hydroxide (LDHs) layer was prepared on the surface of extruded 2195 Al–Li alloy. The preparation method, surface morphology, and chemical composition of the coating were described and characterized in detail. The corrosion and wear protection of the coating on the Al–Li alloy substrate were tested, and the mechanisms of corrosion and wear resistance were discussed. The results indicate that plasma electrolytic oxidation processing can form a thick ceramic film with good interface bonding on the surface of 2195 Al–Li alloy. Hydrothermal reaction in an alkaline solution produces a nanoscale layer of Mg/Al LDHs on the surface of the ceramic film. The LDHs layer fills the micro-pores and cracks in the film and effectively prevents the corrosion medium from permeating and damaging the alloy matrix. The composite coating reduces the surface corrosion efficiency by 99.98 %. Moreover, the composite-coated samples exhibit long-lasting corrosion resistance in seawater and exfoliation corrosion environments. Additionally, the composite-coated Al–Li alloy exhibits wear resistance 1-2 orders of magnitude higher than that of the bare alloy at both room and high temperatures. This study proposes a novel strategy for corrosion and wear protection of Al–Li alloys.

Seawater corrosion resistance of a novel Cu-Ni/γ-Al2O3&CeO2 composite coating on H64 brass

In this paper, γ-Al2O3&CeO2 composite powder (ACp) was prepared by a simple hydrothermal method, and γ-Al2O3 and ACp were deposited on the surface of H64 brass with copper and nickel from sulfate plating bath at a specific deposition current density. The phase composition and morphology of composite powder and coating were studied, and the electrochemical behavior of composite coating in simulated seawater (3.5 wt% NaCl) was evaluated. The results show that γ-Al2O3 and CeO2 are well combined, the corrosion potential and polarization resistance of Cu-Ni/γ-Al2O3&CeO2 composite coating (CNACc) are as high as 0.022 V and 21.107 kΩ•cm2, respectively, which is due to the fact that the composite coating can distort the Cl- corrosion path and play a good role in corrosion resistance.

Seawater Corrosion Resistance of Duplex Stainless Steel and the Axial Compressive Stiffness of Its Reinforced Concrete Columns

In order to explore the corrosion resistance of duplex stainless steel under seawater corrosion and the compressive stiffness of its reinforced concrete columns, this study first performed seawater corrosion resistance tests on HRB400 ordinary steel rebar and S32205 duplex stainless steel rebar. The effect of the corrosion product film on the corrosion behavior was investigated through polarization curve tests and electrochemical impedance spectroscopy tests. The results showed that the corrosion rate of S32205 duplex stainless steel in a seawater environment was approximately 1/15 that of the HRB400 ordinary steel rebar. The anodic polarization curve of duplex stainless steel rebars exhibited a greater slope than that of carbon steel rebars. In the simulated seawater environment, the corrosion rate of these two kinds of steel bars showed different trends. The corrosion rate of ordinary steel bar HRB400 first decreased and then increased, while that of duplex stainless steel S2205 increased steadily. Furthermore, 18 short concrete columns reinforced with ordinary and duplex stainless steel rebars were subjected to the axial compression test and stiffness analysis; the stiffness of the short columns was calculated from the test data. The theoretical values agreed with the test values, with a stiffness calculation error of less than 5%.

Experimental research on pipeless power battery cooling system using shape-stabilized phase change materials (SSPCM) coupled with seawater

With the implementation of zero carbon strategy, electric ships based on lithium-ion power batteries have become development mainstream. Compared with vehicle power batteries, the heat generated by the larger size of ship power batteries is more difficult to be discharged. Therefore, efficient ship power battery thermal management (BTM) systems are urgently needed. Herein, a pipeless cooling system based on shape-stabilized phase change materials (SSPCM) as the seawater channel was proposed and experimentally studied. Firstly, the excellent seawater corrosion resistance of SSPCM channel was proven. Then, the cooling performance of SSPCM channel was compared with the metal channel and SSPCM coupled with metal channel. The results demonstrated that the maximum temperature and maximum temperature difference of the SSPCM channel system were 8.3 °C lower and 1.1 °C lower, respectively than the metal channel system. Although the cooling performance of SSPCM and SSPCM coupled with metal channel was similar, SSPCM had a lighter weight and avoided seawater corrosion. Furthermore, the effects of different factors on the SSPCM channel system were investigated and the key factors were identified by orthogonal experiment. The innovative use of SSPCM channel and seawater provides a new idea for the cooling of the ship power batteries.

Study on Friction and Corrosion Performance of CrTiBN Coating in Artificial Seawater Environment

CrN, CrTiN, and CrTiBN coatings were deposited onto 316 stainless steel substrates using multi-arc ion plating techniques. Their morphology, microstructures, friction performance, and corrosion resistance in simulated seawater were systematically characterized. After being analyzed with X-ray diffraction, X-ray photoelectron spectroscopy, and scanning electron microscopy, the results revealed that CrN coatings had a primary face-centered cubic CrN structure. Following the addition of Ti and B elements, CrTiBN coatings exhibited a cross-sectional structure with hexagonal TiB2 and amorphous BN, displaying the most compact structure. Electrochemical impedance spectroscopy tests indicated that CrTiBN coatings had the highest polarization resistance, the highest phase angle, and the widest frequency range. During electrochemical polarization curve tests, CrTiBN coatings displayed a corrosion potential of 0.11 V, a polarization resistance of 2470 kΩ·cm2, and a minimal corrosion current of 1.94 × 10−8 A/cm2, demonstrating outstanding corrosion resistance. The results from the friction tests indicated that CrTiBN coatings exhibited the lowest friction coefficients of 0.16 and wear rates of 8.18 × 10−7 mm3/Nm. Insights gained from electrochemical friction–corrosion tests revealed that CrTiBN coatings maintained the highest Open Circuit Potential (OCP) throughout the corrosion and friction process. In summary, the introduction of Ti and B has clearly enhanced the friction and corrosion resistance properties of CrTiBN coatings in comparison to CrN coatings.

О МЕХАНИЗМАХ ОБРАЗОВАНИЯ НАНОСТРУКТУРНЫХ ЭЛЕКТРОЛИТИЧЕСКИХ ПОКРЫТИЙ Fe-Ni, Co-Mn, Ni-Cr С ФУНКЦИОНАЛЬНЫМИ СВОЙСТВАМИ

The evolution of modern industry is impossible without the development of new materials and technologies. Nanostructured coatings, in particular electrolytic coatings, are among the most demanded in mechanical engineering. The purpose of this work was to study the different mechanisms of obtaining Fe-Ni, CoMn, Ni-Cr galvanic alloys and their relationship with the specified universal physical and mechanical properties. Fe-Ni alloy is characterized by high microhardness and corrosion resistance in sea water, low cold brittleness; Co-Mn – by a specified phase composition (α-Co >> α-Mn, amorphous and metastable phase Co(OH)2); Ni-Cr – by high coating microhardness, specified phase composition. The main methods of production: high-frequency alternating current for Fe-Ni and Co-Mn alloys; introduction of a special additive (carbamide or H-acid) for Ni-Cr alloy. The main mechanisms are: Fe-Ni due to phase transition α-Fe ε-Fe; Co-Mn by means of high-frequency alternating current and carbamide addition, providing a specified phase composition; Ni-Cr by means of stationary method of addition of H-acid (high-chromium alloy of 68 mass percent of Cr) and carbamide (low-chromium alloy of 25 mass percent of Cr). Recommended uses for electroplating: Fe-Ni – for protection of oil and gas production equipment in the Arctic; CoMn – in modulation systems and as a nanocatalyst in the Fischer-Tropsch synthesis reaction; Ni-Cr – for corrosion-resistant protective coatings in petrochemistry and for resistive elements.

Ni-based coating on 5083 aluminum alloy with Cu-Ni interlayer fabricated by ultra-high-speed laser directed energy deposition

Through the innovative design of interlayer connection materials, a high-performance wear-resistant and corrosion-resistant composite protective coating was successfully prepared on the surface of 5083 aluminum alloy using ultra-high-speed (0.5 m/s) laser energy deposition technology. By conducting orthogonal experiments and analyzing the coating morphology and non-destructive testing results, the optimal process parameters for preparing the Cu-Ni25 alloy interlayer and nickel-based alloy surface protection layer were determined. The bond strength and friction resistance of the composite coating and the substrate were tested by shearing and scratch tests. Furthermore, the wear and corrosion resistance of the nickel-based alloy protective layer and substrate were comparatively assessed using an abrasive wear tester, electrochemical workstation, and salt spray test chamber. The results show that the Cu-Ni25 alloy interlayer plays a good bridge role and realizes metallurgical bonding with the aluminum alloy matrix. Additionally, the addition of the nickel-based alloy surface protection layer yields a significant improvement in deformation resistance, wear resistance, and seawater corrosion resistance compared to the aluminum alloy substrate.

Study on preparation process and seawater corrosion resisting properties of chopped CF/PEEK composites

CF/PEEK composite material is widely used in marine engineering construction due to its characteristics of lightweight, high strength, corrosion resistance, and aging resistance, and it will inevitably produce side materials and wastes in the forming process. Therefore, the research on CF/PEEK recycling is of great significance. Due to the characteristics of PEEK’s high melting point and high viscosity of the solution, it is difficult to recycle and reuse such materials. In this paper, a certain amount of PEEK resin powder is added to improve the hot pressing technology of the chopped prepreg. Through a simulated seawater corrosion experiment, the influence of simulated seawater corrosion on the microstructure and mechanical properties of the composite materials is studied. Combined with the principal component analysis method, the corrosion resistance of the chopped CF /PEEK composite was evaluated comprehensively, which provided a reference for the recycling of thermoplastic prepreg and thermoplastic composite products. The results show that the surface quality and mechanical properties of the composites with resin powder are obviously improved. The resin matrix on the surface of the sample was subjected to salt corrosion by chloride ions in a simulated seawater solution to form local corrosion, resulting in pores, cracks, and other defects. The longer the corrosion time of simulated seawater is, the more serious the surface damage of the composite material is, and the more obviously the mechanical property declines. Principal component analysis showed that the resin content had little effect on the seawater corrosion resistance of chopped CF/PEEK composite.

Effect of synergistic cavitation erosion-corrosion on cavitation damage of CoCrFeNiMn high entropy alloy layer by laser cladding

The CoCrFeNiMn high entropy alloy (HEAs) clad layer was prepared on the surface of 304 stainless steel using coaxial powder feeding laser cladding. The effects of laser energy density on the macroscopic residual stress, crystallographic characteristics, microhardness, corrosion resistance and cavitation erosion (CE) resistance of HEAs clad layer were studied. With the decrease of laser energy density from 45 J/mm2 to 36 J/mm2, pore defects and abnormal coarsening of microstructure in HEAs cladding layer can be effectively avoided, the average grain size can be refined to 74.3 ± 1.7 μm, the average Schmidt factor is 0.43, which also shows the highest dynamic passivation tendency and corrosion resistance in artificial seawater. After 10 h-CE, the carrier density ND in the passivation film of HEAs clad layer can be as low as 3.24 ± 0.08 × 1022 cm−3, and the lowest mean depth erosion rates (MDER) is 0.68 ± 0.07 μm/h, which is much lower than that of 304 stainless steel substrate (4.23 ± 0.13 μm/h). The excellent CE resistance of the HEAs clad layer is attributed to the fact that its grains can effectively resist the plastic deformation and the surface passivation film can maintain a relatively high degree of integrity and continuous level after long aging CE, which has a considerable application prospect in marine engineering.