Corrosion Resistance Of Coatings Research Articles

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.

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.

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

A promising perspective in improving corrosion and wear resistance of plain steel through electrodeposition of thick Ni–Mo–W ternary alloy

In this study, thick Ni–Mo–W ternary alloy coatings (∼24 μm) with 13–27 wt% Mo and 4–11 wt% W were electrodeposited from an alkaline citrate-ammonia bath using direct current. The effect of current density (20–100 mA/cm2) on the composition, current efficiency, morphology, structure, surface topography, tribological behavior, and corrosion resistance of coatings was investigated. The findings revealed an advantageous induced co-deposition of Mo in an electrolyte containing equimolar Mo and W ions. While increasing the current density decreased the Mo content of the coatings, they always had more Mo than W. Increasing the current density, according to SEM and AFM observations, changed the smooth and nodular morphology of Ni–Mo–W coatings to a relatively rough and cauliflower shape. The microhardness of the produced nanocrystalline solid solution coatings was 3.8–4.9 times higher than that of the plain carbon steel substrate. While the hardest coating (793 Hv) deposited at 100 mA/cm2 had the best wear resistance with a volume loss value of 0.04 mm3, it had the worst corrosion resistance among the coatings with icorr = 4.4 μA/cm2. The least hard coating (607 Hv), deposited at 40 mA/cm2, with the highest wear volume loss value of 0.11 mm3, however, was the most corrosion resistant sample with icorr = 1.9 μA/cm2.

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.

Corrosion resistance of hybrid plasma electrolytic oxidation coatings on AZ31B magnesium alloy in simulated body fluid

This study examines the effects of a hydroxyapatite/anatase TiO2/CeO2 coating on the corrosion of AZ31B magnesium alloy in a simulated body fluid. Plasma electrolytic oxidation (PEO) is used to create the coating, and the surface properties are analysed using X-ray diffraction (XRD), atomic force microscopy (AFM) and field-emission scanning electron microscopy (FE-SEM). Contact angle measurements adapted to compare the uncoated substrate (144.74 ± 2.08°) with the coated substrates, which exhibit contact angles of (107.92 ± 2.16°), (95.88 ± 2.06°) and (66.05 ± 2.09°) for the respective coating durations. Increasing the thickness of the coating improves its corrosion resistance. Specifically, a 6-minute PEO coating significantly increases the thickness and provides better protection against corrosion for the AZ31B magnesium alloy. Cross-sectional scans of the coated samples revealed an increase in specimen thickness from 32.92 μm to77.17 μm. Potentiodynamic polarisation tests in a simulated body fluid reveal that the 6-minute coated sample shows the highest corrosion resistance, with the lowest corrosion current density (1.9037 × 10-06) compared to other coatings, indicating strong protection against corrosion. This research proposes a novel method to enhance the corrosion resistance of PEO coatings on magnesium alloys by depositing a thicker layer of hydroxyapatite, anatase TiO2 and CeO2. This approach results in a stronger and more effective protective system against corrosion.

Preparation of AlCoCrFeNi/W-TiC HEA composite coating by laser cladding

In this paper, AlCoCrFeNiW2-x(TiC)x high-entropy alloy coatings (HEA) (x: mass fraction, x = 0, 0.5, 1.0, 1.5, and 2) were prepared on 316 stainless steel (316 L SS) substrate by laser cladding technique. The microstructure, phase, microhardness, wear resistance and corrosion resistance of the HEA composite coatings were discussed by adding different mass fractions of W and TiC particles. The results show that the coatings are metallurgically bonded under the experimental parameters, and the grain size of the coating decreases from the interface to the surface, which is in accordance with the constitutional undercooling criterion. Meanwhile, the contents of W and TiC can adjust the mechanical properties of the coatings. The microhardness of the coatings increases and then decreases with the variation of x value, which can be explained by the large number of TiC particles leading to severe lattice distortions and high internal stresses, which results in the fluctuation of microhardness in the cross-section. The coating exhibits the best microhardness, with an average microhardness of 452 HV when x = 0.5. The wear resistance of the coating is better with an average coefficient of friction of 0.4474 when x = 0.5. However, due to the presence of phase-boundary defects in the composite coatings, which contain cationic and anionic vacancies, When the passivation film is damaged by Cl-, the electrolyte will penetrate along the phase boundary defects and generate corrosive microcells.

Enhancement of ammonia corrosion resistance of coatings through improving dispersion and binding site of graphene oxide in silane coatings

Copper metal is essential to our production process, but it is highly corrosive in an ammonia environment and must be highly valued. Anti-corrosion coating is a simple and cost-effective method of preventing metal corrosion. In this study, a composite silane coating was prepared on copper using an impregnation method with mercaptopropyltriethoxysilane (TPTES) as the silane substrate and graphene oxide (GO) modified with isophorone diisocyanate (IPDI) or isocyanatopropyltriethoxysilane (IPTS) as filler to protect the copper from ammonia corrosion. The coating samples were hanging tested against ammonia corrosion by setting up two corrosive environments: ammonia gas and ammonia water. After 20 days of corrosion, the surfaces of the TPTES/IPDI-GO and TPTES/IPTS-GO coatings remained unchanged under both ammonia environments and the corrosion rate was consistently low at 2–3 μm/y. Additionally, the coating exhibited high protective qualities according to the electrochemical impedance spectroscopy (EIS) test in a 3.5% NaCl solution, which is attributed to the good dispersion that improves the densification and regularity of the coating. Meanwhile, IPTS-GO has a greater binding force with the coating matrix due to the increased number of reactive sites, resulting in further improved corrosion protection. This study provides an idea for research on ammonia-resistant coatings.

Interaction mechanisms and high-temperature erosion-oxidation performance of Cr3C2-NiCrCoMo/nano-TiC coatings

To improve the erosion resistance of typical Cr3C2-NiCr coatings at high temperature, a novel Cr3C2-NiCrCoMo/nano-TiC (NCT) coating was developed and deposited by the high-velocity oxygen fuel spray (HVOF), which involved a cooperative modification of the multi-alloy binding phase and ceramic phase. This study delves into the influence of nano-TiC on the coating’s resistance to erosion under varying impact angles, particularly at 700 °C and 800 °C. Additionally, it explores the interaction between oxidation and erosion processes within the coating. The results indicated that the NCT1 coating with the addition of 3 wt% TiC features lower erosion rates of 1.97, 2.56, 3.14 mg/g under the impact angles of 30°, 60° and 90° at 700 °C, and 2.16, 2.87, 3.49 mg/g at 800 °C compared with original NCC coating. By comparison, the NCT2 coating with 6 wt% nano-TiC shows a deterioration in erosion resistance. The results show that at high temperatures, the erosion resistance of the coating changes from the micro-cutting at lower angles, to the brittle fracture and spalling at higher angles. The appropriate addition of nano-TiC supports and stabilizes the metal binding phase of the NCT1 coating. However, excessive nano-TiC in NCT2 coating contributes to the separation of coating phases during the erosion. The oxidation of the nano-TiC promotes the diffusion of Cr3+ ions, thus accelerating the coating oxidation and deteriorating the high-temperature erosion resistance eventually. The study is anticipated to enhance the longevity and the high-temperature erosion resistance of Cr3C2 cermet coatings, offering significant advancements in practical applications.

Plasma-chemical synthesis of carbide-based vacuum-plasma functional coatings and study of tribological characteristics of friction pairs

The work is devoted to the search for new materials with high functional characteristics using the Avinit vacuum-plasma technologies developed by us, based on the complex use of coating methods (plasma-chemical CVD, vacuum-plasma PVD (vacuum-arc, magnetron), processes of ion saturation and ion surface treatment), stimulated by non-equilibrium low-temperature plasma.Processes of controlled plasma-chemical synthesis of the formation of multicomponent coatings in "metal-carbon" systems – Avinit coating (TiC, MoC) using vacuum-arc sources of ionized atomic fluxes of titanium and molybdenum in an argon-benzene plasma environment were developed and their characteristics were studied depending on their conditions formation.Metallographic studies confirm the possibility of low-temperature application of high-quality wear-resistant high-hard "metal-carbon" coatings with a hardness of 18,000-30,000 MPa, while ensuring good adhesion to the substrate materials (steel DIN 1.2379) without reducing strength and without deteriorating the cleanliness class of the original surface.The conducted tribological tests using the "cube-roller" scheme reveal high tribological characteristics of steel DIN 1.2379 tribopairs with developed coatings and testify to the promisingness of the developed multi-component multilayer coatings Avinit (Ti-C, MoS) for increasing wear resistance and reducing the coefficient of sliding friction in friction nodes.The developed plasma-chemical vacuum-plasma coatings are applied to mock-up samples of the working compressor blades of the GTE of aircraft engines. Proven modes allow to get high-quality, uniform coatings with high adhesion.This gives reason to consider the developed process as an alternative for expanding the range of new Avinit vacuum-plasma erosion-resistant coatings and developing structures of anti-friction wear-resistant coatings to increase the performance of friction pairs in "coating-steel" and "coating-coating" systems.

Effects and mechanism of Zn on the structure and corrosion resistance of microarc oxidation coatings on aluminum alloy

A composite Zn coating is prepared on 2024 aluminum alloy by microarc oxidation (MAO) and the corrosion resistance is investigated. During MAO, the addition of an appropriate concentration of Zn2+ regulates the size and intensity of surface sparks on the sample giving rise to a uniform distribution of MAO current and less large discharge channels. The crystal structure of Al2O3 is compressed and the density of the coating increases. The coating has the Zn3Al94O144 phase and electrochemical tests reveal a corrosion current density (icorr) that is 3 orders of magnitude smaller than that of the coating without Zn doping. Density-functional theory calculations show that Zn inhibits the adsorption of Cl- and consequently reduces the damage to the passivation layer.

Improvement in corrosion resistance of AZ91D Mg alloy in simulated body fluid by cerium-based/stearic acid composite coatings

Magnesium alloys have attracted attention due to their biocompatibility and biodegradability. In this work, composite coatings are developed to potentially improve the corrosion resistance of AZ91D Mg alloy in simulated physiological fluid. Cerium-based/stearic acid coatings were prepared by electrodeposition combined with a simple immersion method. The effect of stearic acid bath concentration on the contact angle and corrosion resistance of the composite coatings was evaluated. The results showed that the stearic acid treatment increased the hydrophobicity of the surfaces of the cerium-based simple coatings. The use of an appropriate stearic acid concentration is a key for the fabrication of hydrophobic surfaces. The duplex coatings were demonstrated to protect the substrate from corrosion in Ringer solution.

Air-based sputtering deposition of TiN(O)/a-TiNxOy multilayer films for enhanced mechanical properties and corrosion resistance

Extensive research has explored multilayer films for their distinctive mechanical and functional properties. This study employs an air-based sputtering technique, using air as a reactive gas under low vacuum conditions, to produce TiN(O)/a-TiNxOy multilayer films. By alternately adjusting the air/Ar flow ratios, the multilayer films with various modulation periods were created. The crystalline TiN(O)/amorphous TiNxOy multilayered structure was confirmed via cross-sectional microscopy and electron energy loss spectroscopy images and mappings. Hardness (H) and elastic modulus (E) initially increased, peaked, and then decreased with the modulation period, reaching a maximum hardness of 31.2 GPa and an elastic modulus of 343 GPa. The enhancements may be attributed to internal compressive stress, interface strain effects, and the inhibition of dislocation propagation throughout the films. Higher H/E ratios (0.09–0.11) and H3/E2 ratios (0.23–0.28 GPa) suggest enhanced resistance to elastic and plastic deformation, surpassing those of single-layered TiN(O). This enhancement is primarily attributed to the hard/soft multilayer design. Potentiodynamic polarization tests revealed improved corrosion resistance with decreasing modulation period, reaching optimal values Ecorr at −0.089 V and Icorr at 0.272 μA/cm2. This improvement is mainly ascribed to the multilayer design, which inhibits direct corrosion through grain boundaries. This air-based sputtering technique offers a facile approach for producing complex multilayer films, promising enhanced mechanical properties and corrosion resistance of coatings for various applications.

Development and electrochemical investigations of enhanced corrosion-resistant Polyvinylcarbazole-TiO2 hybrid nanocomposite coatings on 316L SS for marine applications

The present study focuses on evaluating the corrosion resistance of 316L stainless steel substrates with Polyvinylcarbazole (PVK)/TiO2 hybrid nanocomposite coatings (HNC). Using the chronoamperometry approach, the HNC were electrochemically synthesized on 316L stainless steel substrates, incorporating various weight (%) 1 %, 2 %, 3 % of TiO2 nanoparticles into the PVK matrix. The findings of the surface morphology investigation verified that the 316L SS had a dense and smooth PVK/TiO2 coating. A low surface roughness and high contact value of the PVK/TiO2 coatings are also responsible for the decrease in corrosion rate of the 316L SS. The corrosion protection efficiency of the PVK/TiO2 HNC were investigated through open circuit potential (OCP) measurement, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) analysis in 3.5 wt% NaCl solution. The corrosion rate obtained from the polarization studies of the HNC coatings as follows PVKT-2 < PVKT-3 < PVKT-1 < PVK < 316L SS. Results revealed that an optimal loading of 2 wt% TiO2 nanoparticles significantly enhanced the corrosion resistance of the coating. The enhanced electrochemical impedance response for PVK/TiO2 coatings was verified by EIS experiments. The study demonstrates that the incorporation of TiO2 nanoparticles into the PVK matrix effectively creates a barrier layer at the coating-metal interface, inhibiting the entry of aggressive ions. Microhardness studies revealed the increase in hardness value of the PVK and PVK/TiO2 coatings indicated the protective nature of the coating and provided high mechanical strength to 316L SS. The tape adhesion tests carried out on the coated specimens also indicated a good adhesion of the PVK/TiO2 on the 316L SS surface.

Fabrication Aspects and Performance Characterization of α-Al2O3/AlPO4 Based Sandwich Configuration Flow Channel Inserts and Coatings for High Temperature Liquid Metal Applications

Abstract Liquid metals (LMs) exhibit several key characteristics justifying their utilization as coolants and breeders for nuclear fusion reactors and advanced fission reactors. In fusion reactors, the LMs confront an exorbitantly high flow retarding force, due to the magneto-hydro-dynamics (MHD) effect, imposing significant demands on the pumping power and designs of ancillary coolant systems. Corrosion of structural materials leading to activated corrosion products and coolant chemistry control are some of the vital issues common to both fusion and fission reactors employing liquid lead (Pb) and its alloys. To address these concerns, different technological solutions such as flow channel inserts (FCIs) and high temperature compatible corrosion resistant coatings are being investigated to provide a chemical and/or electrical isolation between the LM and structural material for advanced reactors. In this study, three different prototype geometries (circular, square, and 90 deg bend) of steel-insulator-steel sandwich FCIs are fabricated for fusion reactor applications and an extensive characterization of the electrical insulation is performed over an operating temperature range of 100 °C–600 °C. Welding trials and pneumatic pressure tests up to 10 kg/cm2 (g) are performed on the assemblies to validate the electrical and mechanical integrity over typical fusion reactor operational regime. This paper presents detailed fabrication aspects along with quantitative estimations of insulation filling density, electrical insulation performance and, for the first time, a detailed systematic study of insulation degradation resulting from the combined effects of tungsten inert gas (TIG) welding, exposure to pressure and machining operations on these FCIs. The paper also provides critical details derived from the metallurgical examinations and visual observations from the destructive tests executed on the prototypes. Further, from an implementation perspective toward Lead-cooled Fast Reactors (LFRs), a preliminary feasibility assessment of the α-Al2O3/AlPO4 coating is performed through thin film deposition trials on planar and non-planar substrates followed by mechanical characterizations, such as coating thickness, surface roughness, adhesion strength and microhardness. Metallurgical analyses are presented and discussed to assess Pb ingress after 700 h of continuous exposure to molten Pb alloy at 300 °C–400 °C.