Corrosion Resistance Of Coatings Research Articles

Tribocorrosion behavior of GCr15 steel in water–glycol fire-resistant hydraulic fluids (HFC) containing seawater

With the development of deep-sea exploration technology, the technology of fire-retardant hydraulic fluid (HFC) has played an important role in the power transmission of exploration equipment. However, the mechanism of the influence of seawater content on the tribocorrosion behavior of HFC remains unclear. In this study, the effects of different seawater contents on the tribological and corrosive properties of HFC were systematically investigated. The results showed that when the seawater concentration exceeds 30 wt%, a soft Mg-containing reaction film is formed in the friction contact area owing to seawater corrosion, thus effectively improving the sintering load and wear resistance to some extent. By contrast, with increasing seawater concentration, the lubricity declines, the wear intensifies, and the extreme pressure characteristics decrease significantly. The comparative analysis shows that the composition of the wear and corrosion reaction films significantly differs under high-concentration seawater conditions, which is also a key factor affecting the friction and corrosion behavior of HFC. This study provides a direction for the research and development of wear- and corrosion-resistant materials and coatings on the surface of deep-sea exploration equipment.

Melamine-Modified Graphene Oxide as a Corrosion Resistance Enhancing Additive for Waterborne Epoxy Resin Coatings

Waterborne epoxy resin (WEP) coatings are widely used in various fields due to their environmentally friendly properties, yet their corrosion resistance and shielding properties demand further refinement. In this work, melamine-modified graphene oxide (MGO) was synthesized using surface covalent functionalization, and a novel waterborne epoxy/modified graphene oxide coating (WEP/MGO) was prepared. The optimal modification effect was obtained by exploring different proportions of melamine, which led to significant improvements in the corrosion resistance of WEP. Furthermore, the corrosion protection efficiency of WEP/MGO coatings was systematically evaluated by examining the impact of different additions of MGO. The impedance modulus at the lowest frequency was increased from 3.77 × 108 Ω·cm2 of WEP to 2.85 × 109 Ω·cm2 after immersion in 3.5% NaCl for 48 h, when the addition of MGO was 0.1 wt.%. And the corrosion expansion at both the scratch and corrosion spot frequencies of the WEP-coated samples displayed a remarkable attenuation following exposure to salt spray for 300 h. The corrosion resistance and barrier properties of WEP coatings have been considerably enhanced.

Effect of titanium interlayer configurations on residual stresses and performance of titanium/titanium nitride multilayer coatings

Multilayer coatings provide an effective measure to control and optimise of residual stresses, enhance coating adhesion, fracture toughness, wear and corrosion resistance of coating system. In this study, we designed and produced bi-layer and four-layer titanium/titanium nitride magnetron sputtered coating configurations by altering the position of the interlayer. The in-plane residual stresses in different coating configurations are measured by multiple peak grazing incidence X-ray diffraction techniques. Subsequently, the effect of different compressive residual stresses on adhesion, mechanical properties, wear and corrosion resistance of coatings are investigated. Results show that the position of interlayer in multilayer coating configuration has a great impact on relaxation of residual stresses. The residual stresses are relieved by 26% and 46% by lowering the position of titanium interlayer from 800 nm at the top to 1000 nm and 1200 nm, respectively. The nanoindentation hardness is decreased by 11% and 13%, respectively. The wear rate of multilayer coating having interlayer position at 800 and 1000 nm from the top is ≈ 23% lower compared to bilayer however it is increased by ≈ 50% when interlayer coatings position changed to 1200 nm from the top. The interposition of interlayer in multilayer coating configurations decreased the corrosion current density by ≈ 50%. All multilayer coatings including higher residual stresses show better adhesion to the substrate compared to bilayer coatings which shows severe delamination.

A Review of Corrosion-Resistant PEO Coating on Mg Alloy

The corrosion problem of Mg alloy limits its application in many engineering fields. Plasma electrolytic oxidation (PEO) is an economical and eco-friendly technology that can create a dense oxide layer on Mg alloy, offering a solution to the corrosion issue. This research summarizes the use of PEO technology in developing corrosion-resistant coatings for Mg alloys and examines the growth mode and corrosion process of PEO coatings. It is concluded that current efforts to enhance the corrosion resistance of PEO coatings on Mg alloys can be categorized into two approaches: improving the internal structure of the coating and enhancing the phase composition. This includes optimizing coating thickness, roughness, and density; repairing micropores and cracks; and introducing corrosion-resistant compounds by doping. Micropores and cracks are identified as vulnerable points for corrosion, and sealing is an effective strategy to address this. By modifying the phase composition of the coating, corrosion occurrence can be minimized, significantly boosting the corrosion resistance of Mg alloys. Finally, future challenges and potential advancements in corrosion-resistant PEO coatings for Mg alloys are discussed.

Effects of spraying power on Fe-based amorphous coatings

To avoid the corrosion damage caused by cavitation and sediment erosion on the turbine blades, Fe-based amorphous coatings were deposited on steel of hydraulic turbine blades using plasma spraying with various spraying power. The effects of spraying power on the microstructure, electrochemical corrosion and wear resistance were systematically studied. Results show that the coatings have remarkable corrosion resistance and wear resistance compared with the substrate. Porosity is the most critical factor influencing the corrosion resistance of coatings. The anti-corrosion performance increases and the wear rate decreases as the spraying power increases. The coatings prepared at 25 kW has excellent corrosion resistance and wear resistance, with a corrosion rate of 0.011 mm·a−1, and a wear rate of only 5.91 mm3·N−1·m−1.

Molten salt corrosion behavior of laser remelted PS-PVD YSZ thermal barrier coatings

Molten salt from the service environment leaches Y2O3 from yttria-stabilized zirconia (YSZ), threatening the security of thermal barrier coatings (TBCs). In this study, we compared the molten salt corrosion resistances of YSZ coatings prepared via plasma-spraying physical vapor deposition (PS-PVD) before and after laser remelting. At 1000 °C, the molten salt reacted with YSZ particulates in the PS-PVD YSZ coating and infiltrated the gaps between quasi-columnar crystals, resulting in phase transition of the coating and column breakage. A dense glazed layer was formed on the YSZ coating surface after remelting by the low-energy-density laser, which prohibited the penetration of molten salt and improved the hot corrosion resistance of the YSZ coating. By contrast, the failure of the high-energy-density laser-treated YSZ coating was accelerated due to the significant interfacial stress from the thick glazed layer and volume expansion caused by the corrosion products. Our investigation revealed the structural evolution of the PS-PVD YSZ coating under hot corrosion conditions, emphasized the role of laser remelting, and could serve as a guideline for TBCs modification.

Anti-corrosion behavior of magnesium phosphate (Mg–P) coatings after exposure to elevated temperatures

In this study, Mg–P coatings, prepared on steel alloy substrates, were exposed to temperature from 25 °C to 900 °C. The effects of high temperature exposure and the salt spray test on the anti-corrosion ability of Mg–P coating were investigated in detailed. The results show that the corrosion resistance of coatings decreases continuously from 25 °C to 700 °C, then increases at 900 °C of exposure. However, the corrosion resistance of coatings after 2000h salt spray test was significantly improved. In particular, the corrosion rate of the coating is only one-ninth that of the coating before the salt spray test when the temperature is 900 °C. Furthermore, the microscopic characterization test revealed that a dense oxide layer form between the steel alloy substrate and the coating when temperature exceed 400 °C. Besides the crystal phase transition and oxide layer, the synergistic effect of the secondary reaction of the raw material is the key factor to ensure that the coating still has good corrosion resistance at a high temperature.

Cl2 corrosion resistance of SiC coatings with different morphologies

The objective of this study was to investigate the corrosion resistance of SiC coatings with various morphologies on graphite in a high-temperature Cl2 environment. The researchers conducted a thorough assessment of the coating's corrosion resistance by comparing micro-morphology, changes in surface roughness, and mass loss rates before and after corrosion. The findings reveal that the SiC layer can undergo a chemical reaction with Cl2 at high temperatures, resulting in the formation of layered or granular carbon on the grain surface. Corrosion occurs primarily at the grain boundaries. Among the tested samples, the S30 sample, characterized by the smallest grain size with average grain size 7.15μm, exhibited the highest corrosion resistance. It showed a low mass loss rate of only 0.72 % and a minimal surface roughness change rate of 11.3 % before and after corrosion, whereas the S40 exhibited the highest mass rate loss of 1.2 % and S20 had the highest roughness variation rate 54.3 %.

Comparative study of anti-corrosion properties in different CrN/WC-Co duplex coatings processed by PVD/HVOF

WC-Co coatings produced by high-velocity oxy-fuel (HVOF) show the high porosity which limits their application in seawater. Herein, we prepared CrN/WC-12Co and CrN/WC-10Co-4Cr duplex coatings combined with the physical vapor deposition (PVD) and HVOF technologies. The microstructure and the corrosion behavior were studied and compared with WC-Co coatings. The CrN film covers the pores on the surface of WC-Co coatings which enhances the corrosion resistance. In addition, the corrosion products of WC-10Co-4Cr coating seal the defects in the CrN film, and further improve the corrosion resistance of the duplex coatings. The CrN/WC-Co duplex coatings enhance the corrosion resistance of WC-Co coatings, especially for CrN/WC-10Co-4Cr, which greatly increases the corrosion potential and reduces the corrosion current density of WC-Co coatings.

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

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

A new method for preparing Mg-Al-layered double hydroxides coating using supercritical CO2 fluid

A new method for preparing Mg-Al-layered double hydroxides (Mg-Al-LDHs) coating using supercritical CO2 fluid was developed. The morphologies, structures, compositions, and corrosion resistances of the surface coatings were investigated. Unlike traditional methods, the method using supercritical CO2 fluid generated ultrafine nanocrystal coatings with an average size of 30 nm, and a thickness of ca. ∼ 11 μm. The Mg-Al-LDHs coating was mainly composed of C, O, Mg, and Al. Corrosion resistance measurements show that the amount of hydrogen evolution for the nanocrystal LDHs coating was only 0.133 mL·cm−2, the polarisation resistance was 3174.9 Ω·cm2, and the immersion test corrosion grade of 7G. Finally, the formation mechanism of the Mg-Al-LDHs coating under supercritical CO2 fluid was proposed.

Enhanced corrosion resistance of graphite-like carbon coatings via dense ta-C interlayer encapsulating

Taking the combination of atomic bond density, in this work, the tetrahedral amorphous carbon (ta-C) layer with high sp3 bond were especially introduced into the sp2-riched graphite-like carbon (GLC) coatings, using a hybrid filtering cathodic arc and magnetron sputtering deposition technique. The focus was elaborated on the electrochemical behavior of coatings against the stimulated chloride solutions for marine applications. Results showed that inserting dense ta-C layer significantly encapsulated the intrinsic pore defects within GLC growth, thereafter enhancing the corrosion resistance remarkably. In particular, the coating porosity was reduced from 10.84 % for pristine GLC system to 3.19 % for GLC with ta-C sealing layer, accompanying with a reduction in corrosion current to 7.8 × 10−9 A/cm2 and an increment in protective efficiency to maximum value of 95.49 %. The small angle X-ray scattering (SAXS) analysis evidenced qualitatively that the coating porosity was suppressed greatly, which were well consisted with the enhanced corrosion resistance of GLC coating with ta-C sealing layer. Furthermore, the balance between pores sealing and interfacial matching could be tailored by controlling the thickness ratio of ta-C and GLC layers, enabling the achievement of both the compact structure and the superior corrosion resistance. These observations offer a new promising strategy to develop the protective coatings for harsh marine environment that required both excellent capability against corrosion and friction with long lifetime.

Enhancing the high-temperature corrosion resistance of HVOF-sprayed NiCoCrAlY coating in marine environment by Pt modification and pre-oxidation

To prolong the service lifetime of hot-section components used in marine environment at elevated temperatures, it is crucial to explore and develop high-temperature corrosion-resistant coatings. High-velocity oxygen fuel (HVOF) sprayed NiCoCrAlY, Pt-modified NiCoCrAlY and pre-oxidized Pt-modified NiCoCrAlY coatings were prepared and investigated. This study is concerned with the performance of three coatings in a simulated marine environment based on the phase composition of corrosion products and microstructure evolution of coating samples combined with first-principles density functional theory. The results show that the NiCoCrAlY coating was subject to accelerated corrosion and extensive aluminum depletion, leading to premature coating failure. The high-temperature corrosion resistance of Pt-modified NiCoCrAlY coating was found to be better than that of NiCoCrAlY coating. In contrast, the pre-oxidized Pt-modified NiCoCrAlY coating offered long-lasting protection and exhibited the best corrosion resistance, which is attributed to the positive synergistic effect between Pt modification and pre-oxidation.

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

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

Performance and Formula Optimization of Graphene-Modified Tungsten Carbide Coating to Improve Adaptability to High-Speed Fluid Flow in Wellbore

In order to improve the erosion resistance of steel PDC (Polycrystalline Diamond Compact) bit under high-speed fluid flow conditions underground, it is necessary to develop a high-performance erosion-resistant coating. In this paper, laser cladding was used to prepare the new coating by modifying tungsten carbide with graphene. And the effects of tungsten carbide content and graphene content on the coating performance have been thoroughly studied and analyzed to obtain the optimal covering layer. The research results indicate that, for new coatings, 60% tungsten carbide and 0.3% graphene are the optimal ratios. After adding tungsten carbide, the hardness has significantly improved. However, when the tungsten carbide content further increases more than 30%, the increase in hardness is limited. In addition, when the content of graphene is more than 0.3%, the branched structure becomes thicker. In detail, this is a phenomenon where the segregation of Cr, Si, and W becomes very obvious again, and the segregation of Fe occurs at the Ni enrichment site. The research results contribute to the development and optimization of high-quality erosion-resistant coatings under the high-speed flow conditions in wellbore. These are of great significance for improving the efficiency of oil and gas exploration and development.

Corrosion resistance of ceramic coatings formed by microarc oxidation on aluminium alloy AK4-1

Corrosion resistance of ceramic coatings formed by microarc oxidation on aluminium alloy AK4-1

Enhancing anticorrosive performance of epoxy-based coatings using magnetite/graphene hybrids modified with ionic liquids

Hybrid materials based on magnetite (Fe3O4) and graphene nanoplatelets (GNP) were prepared by the in situ co-precipitation synthesis of Fe3O4 in the presence of GNP aqueous dispersion. Alkyl-phosphonium–based ionic liquids bearing bromide (IL102) and diethyl phosphate (IL169) as the counter-anions were used for the first time to improve the dispersion of GNP. The successful preparation of the hybrids and the final incorporation of the ILs in the hybrids were confirmed by thermogravimetric analysis (TGA) and Fourier transform infrared (FTIR) spectroscopy. The exfoliation of the GNP sheets and the incorporation of Fe3O4 particles on the GNP surface were confirmed by transmission electron microscopy. The effect of different hybrids on the corrosion resistance of the epoxy coatings was evaluated in saline medium using by electrochemical impedance spectroscopy (EIS). Hybrids prepared by the in situ synthesis of magnetite (Mag@GNP) promoted better corrosion resistance than pure magnetite or those hybrids introduced into the epoxy coatings by physical blends, due to better dispersion of the former fillers into the epoxy matrix. The best anti-corrosion response was achieved using 5 % of Mag@GNP 102 due to the better filler dispersion and higher amount of incorporated ionic liquid in the system, which can act as inhibition agent for the corrosion process.

A mechanically robust superhydrophobic corrosion resistant coating with self-healing capability

Conferring self-healing capability represents an effective approach for extending the lifespan of multifunctional superhydrophobic coatings. Presently, reported self-healing superhydrophobic coatings exhibit scratch-healing capabilities ranging from 5 μm to 40 μm. However, achieving large-scale scratch-healing (>100 μm) remains a significant challenge within this research domain. In this paper, we introduces the design and fabrication of a dual-layer self-healing superhydrophobic anti-corrosion coating using polycaprolactone (PCL), EASTMAN Kristalex 3085 resin (EK), epoxy resin (EP), and 1H, 1H, 2H, 2H-perfluorodecyltriethoxysilane (PFDTES) modified silica particles via a facile spray-coating approach. The surface morphology, chemical composition, wettability, self-cleaning, damage-healing, and anti-corrosion behaviors of the coating were thoroughly evaluated. Results demonstrate that the coating exhibits self-healing capabilities across multiple scratch-damage scales (45 μm, 55 μm, and 100 μm), particularly exhibiting superior large-scale scratch-healing ability. Furthermore, the coating displays outstanding corrosion resistance, with the charge transfer resistance (Rct) increasing by nearly 8 orders of magnitude compared to the bare Q235 carbon steel substrate. Although the corrosion resistance of the scratch-damaged coatings significantly decreases, the anti-corrosion capability of the scratch-healed coating is effectively restored to its initial state, showcasing excellent anti-corrosion sustainability. Additionally, the coating demonstrates remarkable mechanical stability, withstanding 90 sandpaper abrasion cycles and 70 tape-peeling cycles.

Study on the erosion and corrosion resistance of graphene oxide and polymer composite coatings

Study on the erosion and corrosion resistance of graphene oxide and polymer composite coatings

Study on the Microstructure, Corrosion Resistance and Dielectric Properties of Atmospheric Plasma-Sprayed Y2O3 Ceramic Coatings

Atmospheric plasma spraying (APS) is one of the most efficient processes for the preparation of yttrium oxide (Y2O3) ceramic coatings. Changing the spraying process parameters can significantly improve the microstructure and enhance the coating properties. In this study, the combination of plasma-spraying process parameters (current, spraying distance, and argon (Ar) flow) was varied by Response Surface Methodology (RSM) with the help of Minitab 19 software. Applied to the design of experiments, improvement of errors, and prediction of microstructure property results, the optimization and validation of experimental parameters for attaining the desired microstructure of Y2O3 coatings, especially porosity, was achieved. Process parameters were optimized by RSM: current 613.64 A, Ar flow rate 46.92 L/min, spray distance 15.38 cm, and optimum porosity 1.8% after optimization. Electrochemical corrosion experiments and breakdown voltage experiments revealed that the corrosion resistance and dielectric properties increased significantly as the porosity of the coatings decreased. Therefore, by optimizing the plasma-spraying process parameters, the porosity of the coatings can be significantly reduced and the corrosion resistance and dielectric properties of Y2O3 coatings can be effectively improved.