Protective Coatings Research Articles

Anticorrosive pigment for smart and green protective coatings: An alkyd resin coating incorporating lanthanum-loaded hydroxyapatite, derived from a phosphate mining industry by-product

Intelligent anti-corrosive coatings have gained considerable interest as a method to protect metals. This approach offers an effective strategy for mitigating corrosion by providing advanced control over the process. In this research, lanthanum-loaded hydroxyapatite pigment (La-HAp) was successfully synthesized using phosphate sludge (PS) waste. The pigment was incorporated into an alkyd resin coating to provide smart corrosion protection for mild steel exposed to a saline solution. The synthesized pigments were characterized using various analytical techniques, including FTIR, XRD, and SEM−EDS. The inhibitory performance of La-HAp on mild steel submerged in a 3% NaCl solution was evaluated using linear polarization and EIS techniques. The findings demonstrated substantial inhibitory effectiveness, achieving 82% inhibition efficiency. Further investigation compared the protective capabilities of modified (C-La-HAp) and reference (C-Ref) alkyd coatings on carbon steel using EIS. The results indicated significant corrosion protection enhancement with 5% La-HAp, showing a polarization resistance of 19.7 MΩ·cm2 after four weeks of immersion in the aggressive solution. This corrosion resistance is primarily attributed to the formation of a barrier against the corrosive environment and the trapping of Cl- ions by the HAp, accompanied by the release of La, phosphate, and calcium ions. La ions react with OH- ions produced in the cathodic zones to form a uniform protective layer of Lahydroxides, while iron orthophosphates provide additional protection at anodic sites. This synergistic blend of mechanisms imparts intelligent corrosion-inhibiting properties to the alkyd resin, effectively guarding against the damaging effects of corrosive agents.

Large Range Curvature Measurement Using FBGs in Two-Core Fiber with Protective Coating

In this work, we propose a fiber Bragg grating (FBG)-based sensor for curvature measurements. Two gratings are inscribed through the protective coating in a specialty optical fiber using focused femtosecond laser pulses and point-by-point direct writing technology. One grating is inscribed on the central core adjacent to an air channel, while the other is inscribed on the eccentric core. The bending characteristics of the two-core fiber strongly depend on the bending direction due to the asymmetry of the fiber cores. A bending sensitivity of 58 pm/m−1 is achieved by the FBG in the eccentric fiber core over the curvature range of 0–50 m−1 . Temperature and humidity cross-sensitivity could be significantly reduced by analyzing the differences in peak shifts between the two gratings. The sensor features a large sensing range and good robustness due to the presence of its protective buffer coating, which makes it a good candidate for curvature sensing in engineering fields.

Mechanism-Guided Rational Design of Anode Coatings for Aqueous Zinc Ion Batteries.

Aqueous zinc ion batteries (ZIBs) hold promises as a safer, more cost-effective, and environmental-friendly alternative to lithium-ion batteries, especially for stationary energy storage. Recent advancements in protective anode coatings, which fine-tune zinc ion solvation structure, have yielded significant improvements in the aqueous ZIB performance, addressing dendrite formation and side reactions, thereby prolonging cycle lifetime. Understanding the underlying mechanisms of these coatings as ions sieves is crucial for further optimization and achieving long-term stability, which is a key requirement for practical applications. This concept explores recent developments in ZIB anode coatings from the view of molecular mechanisms and points out future research directions.

Mechanical and high-temperature steam oxidation properties of Cr coatings deposited via high-power impulse magnetron sputtering

Applying protective coatings to Zr alloy cladding surfaces is one of the better methods to design fuel tolerant materials. In this study, the surface of a Zr-4 alloy was coated with Cr using high-power impulse magnetron sputtering. Furthermore, the mechanisms by which bias voltages affect the mechanical characteristics, resistance to high-temperature steam oxidation, and coating structure were elucidated. The coating exhibits a strong (200) weave structure with coarse grains at a bias voltage of -100 V. With increasing bias, the energy of deposited particles increases, grains continue to grow, (200) preferential growth orientation disappears, and the coating exhibits a (110) crystal orientation. The growth structure of the coating first shows a tendency to be dense and then loose. For the Cr coating with a (200) crystal orientation, a dense oxide layer is preferentially formed after oxidation, which can effectively block the internal diffusion of O. With increasing oxidation time, coarse Cr grains can effectively block the external diffusion of Zr. Furthermore, the Cr coating exhibiting a (110) crystal orientation was severely oxidized after oxidation, resulting in the formation of cracks at the film base; this accelerated the outward diffusion of Zr.

Enhanced Polyaspartate Polyurea Reinforced with Boron Nitride Nanosheets for Protective Coatings

Enhanced Polyaspartate Polyurea Reinforced with Boron Nitride Nanosheets for Protective Coatings

Effect of Protective Coating Layer and Overlapping Factor on the Microstructure and Mechanical Properties of Rene-80 Ni-Based Superalloy in Laser Shock Peening Process

Effect of Protective Coating Layer and Overlapping Factor on the Microstructure and Mechanical Properties of Rene-80 Ni-Based Superalloy in Laser Shock Peening Process

Investigation of Structural, Elastic and Magnetic Properties of CoCr2−xZrxO4 Nanoparticles

This study investigates the impact of zirconium substitution on the structural, elastic and magnetic properties of CoCr2O4 nanoparticles. A series of CoCr2−xZrxO4 nanoparticles, x = 0.00, 0.05, 0.10, 0.15 and 0.20, are synthesized via the co-precipitation method. X-ray diffraction (XRD) patterns affirm the formation of single-phase cubic structure with the space group Fd3m. Special attention is given to accurately calculating the average crystallite size (D) and lattice parameter (a) using Williamson–Hall (W–H) analysis and the Nelson–Riley (N–R) extrapolation function, respectively. The increase in Zr4+ content leads to a reduction in crystallite size and an increase in the lattice parameter. Elastic properties are estimated from force constants and the lattice constant, determined from FTIR and XRD, respectively. The observed changes in the elastic constants are attributed to the strength of interatomic bonding. The stiffness constants decrease, while Poisson’s ratio increases with increasing Zr4+ content, reflecting the increase in the ductility of the prepared samples. As the Zr4+ content increases, the stiffness constants decrease, and Poisson’s ratio increases, reflecting enhanced ductility of the samples. Furthermore, as Zr4+ content rises, Young’s modulus, the rigidity modulus and Debye temperature decrease. The magnetic hysteresis loop measurements are carried out at room temperature using a vibrating sample magnetometer (VSM) over a field range of 25 kg. Unsubstituted CoCr2O4 exhibits ferrimagnetic behavior. As Zr4+ content increases, saturation magnetization (Ms) and magnetic moment decrease, while remanent magnetization (Mr) and coercivity (Hc) initially decrease up to x = 0.10, then increase with further increases in x. The novel key of this study is how Zr4+ substitution in CoCr2O4 nanoparticles can effectively modify their elastic moduli and magnetic properties, making them suitable for various applications such as flexible electronics, protective coatings, energy storage components and biomedical implants.

Influence of NiCrAlY coating on anti-corrosion of M951 alloy

M951 alloy is a cast nickel-based super-alloy widely used in gas turbines and aircraft engines, thus a suitable high temperature protective coating must be applied on its surface to enhance the corrosion resistance. In this research, NiCrAlY coating was deposited on M951 by arc ion plating. TGA at 1100 °C, cyclic oxidation at 1000 °C and hot corrosion in molten Na2SO4+25 wt% K2SO4 salt at 850 °C of M951 bare alloy and NiCrAlY coating specimens were investigated respectively. After TGA and cyclic oxidation, mixed oxides of NiO, NiAl2O4, Nb2O5 and Al2O3 formed on M951 surface, which spalled seriously during cyclic oxidation process. Thin, continuous and adhesive α- Al2O3 formed on the surface of NiCrAlY coating after both oxidation process. In molten Na2SO4+25 wt%K2SO4 salt at 850 °C, catastrophic corrosion occurred for the M951 alloy only after 10 hours, while thin and continuous θ- Al2O3 film formed on the surface of the NiCrAlY coating. In a word, NiCrAlY coating greatly improved the high temperature oxidation and hot corrosion resistance of the M951 superalloy. This study will further refine the oxidation and corrosion behaviors of M951 superalloy under different high temperature protective coatings and provides theoretical and experimental basis for the application of M951 superalloy in corrosive environments.

Boosting Erosion‐Corrosion Resistance: Collaborative Ni–P Electroless Deposition on Poly‐Amino‐Alcohol@Functionalized GO Matrices

AbstractIn recent years, protective coatings have become crucial in graphene‐based chemical studies. This research investigates the anticorrosive properties of coatings created by co‐depositing carbon compounds. Electroless Ni−P‐PAA@F‐GO coatings were applied to stainless steel by adding various amounts of PAA@F‐GO particles to the Ni−P bath. The coated samples were analyzed using X‐ray diffraction and micro‐hardness tests, revealing a peak hardness of 764 HV at 30 mg/L PAA@F‐GO, compared to 521 HV for standard Ni−P coatings. Corrosion performance was evaluated in a 3 % sodium chloride solution, showing that despite a higher corrosion‐erosion rate. Although the coated samples exhibited a corrosion‐erosion rate 4.7 times higher than untreated samples, the mass loss was notably more pronounced in the untreated samples. The study found that adding PAA@F‐GO particles improved corrosion resistance and durability, with optimal results at a specific particle concentration. The enhanced performance is attributed to the increased roughness, impermeability, and hydrophobicity of the functionalized graphene oxide.

From Wet to Protective: Film Formation in Waterborne Coatings.

The importance of anticorrosive coatings cannot be overstated, as they play a vital role in safeguarding assets and infrastructure across various industries. Within this context, the emergence of waterborne (WB) coatings stands out for their paramount significance, offering a sustainable alternative to traditional solvent-based (SB) coatings and addressing pressing environmental concerns. Despite their eco-friendliness, the complexity of their film formation mechanism and the lack of understanding present challenges in enhancing the performance of waterborne coatings for corrosion protection. These coatings are created by dispersing polymers in water, which then form a protective film on a substrate. The process involves stages like water evaporation, particle packing, and polymer interdiffusion, often leading to films with defects and inferior protection against extremely corrosive environments compared to SB coatings. This Review scrutinizes the interplay of factors affecting film formation in application, including coalescing agents, environmental factors, and application conditions. A comparative analysis between SB and WB coatings is also featured to shed light on the performance gap under harsh conditions. This Review discusses analytical techniques for studying film formation, aiming to guide future research toward improving WB coatings' durability and effectiveness. In compiling this collective wisdom, this Review emphasizes the translation of theoretical understanding into practical knowledge, equipping formulators with actionable insights to optimize WB coatings for real-world application and performance.

Synthesis and evaluation of substituted cyclodiphosph(V)azane sulfonamide and their Fe(III), Ag(I) metal complexes as novel insecticides for protective coatings

Purpose This study aims to synthesize new cyclodiphosph(V)azane derivatives, 2,2,4,4-tetrachloro-1,3-di-[o-nitriyl]-2,4-di-[N-(pyrimidin-2-yl)benzenesulfonamide]-1,3,2,4- diazadiphosphetidine(H2L) ligand and their Fe(III) and Ag(I) metal complexes as insecticides for protective coatings. Design/methodology/approach The substitutes of cyclodiphosph(V)azane sulfonomide and their Fe(III), Ag(I) metal complexes were prepared and confirmed by a combination of elemental analyses, mass spectra, conductivity measurement-vis, FTIR, 1H,13C-NMR TGA, XRD and Docking investigation of the ligand and some complexes to verify their drug ability. The prepared compounds have been incorporated with a polyurethane (PU) coating formula. Gloss, scratch resistance, flexibility and adhesion are some of the coating attributes investigated; mechanical capabilities include impact resistance and shore hardness and physicochemical properties such as chemical resistance of coated PU samples are also investigated. Findings The results of the experiments revealed that all PU coatings based on the prepared compounds had good scratch resistance which varied from >1.8 to >2.2 kg. Gloss value varied from 85 to 95 and impact resistance from 1.4 to 2.0 (J), whereas the authors noticed that there was no effect of the prepared compounds in the flexibility and adhesion test. These PU coatings have excellent chemical resistance except the alkali resistance. Insecticide activities of the prepared compounds are promising for resistance to these insects. It was noticed that, metal complex > incorporated PU with Fe (III) metal complex > incorporated PU with ligand. Originality/value Insecticide paints based on cyclodiphosph(V)azane sulfonamide and their Fe(III), Ag(I) metal complexes as insecticide agents are novel.

Enhancing high-temperature chloride molten salts corrosion resistance of 310S steel with Si-added Ni–Al coating

Ni–Al based coating is one of the common high temperature and corrosion resistant protective coatings. In the present paper, the effect of Si content on the formation of Al2O3 layer and the corrosion resistance of Ni–Al coating to chloride molten salt was studied. The research results show that the Ni–Al coatings with varying Si content mainly form NiAl2O4 and Al2O3 oxide layers after pre-oxidation, and form a three-layer structure after molten salt corrosion. The appropriate amount of Si added to the Ni–Al coating can promote the formation of the α-Al2O3 layer during pre-oxidation and thermal corrosion, improving the corrosion resistance of the coating to high temperature chloride molten salt, and hindering the diffusion of Cr elements. Particularly, the Ni–Al coating with Si content of 1.2 at.% has the thickest and densest Al2O3 protective layer, showing the best corrosion resistance. The simulation results shows that compared with the Ni–Al coating without Si, the Cl atoms in the Si-added Ni–Al coating need to overcome greater energy barriers to diffusion during the molten salt corrosion process, which also indicates that the addition of Si can improve the corrosion resistance of the coating.

Assessment of the Functional Properties of the Surfaces of Ductile Cast Iron Parts

Modern technology allows ductile cast iron parts to be efficiently machined while ensuring a relatively long tool life. One of the basic indices describing the susceptibility of ductile cast irons to change in volume, shape, and dimensions under machining conditions is their machinability. Machinability can be expressed directly in terms of the values of basic quantities such as periodic cutting speed and roughness. At the same time, machinability is a relative quantity evaluated alternatively. This means that the machinability of ductile cast iron can be good, allowing high cutting speeds to be achieved, but it can also be poor, expressed in terms of poor surface quality. In the experimental research carried out, an attempt was made to determine the limit values of the cutting speed, beyond which one should not exceed, in order to increase the efficiency of the machining process. The surface roughness, unlike the periodic cutting speed, is a quantity defined in the product design documentation, so its limits must be observed. In addition to the usual indices of surface geometric texture, the research analysed alternative indices for determining the condition of surface geometric texture and the influence of periodic cutting speed on their values. In the conclusions, valuable recommendations are given for designers and technologists on the purpose and functionality of product surfaces and how to define them. Methods of specifying tribological characteristics, hydrophobic or hydrophilic properties, as well as the ability to retain fluids and maintain protective coatings of ductile cast iron parts after machining are described, for which relative values, depending on the machining parameters used, can vary from about 10 to even 30%.

High-temperature oxidation resistance and wear properties of functionally graded CrHfNbTaTiN high-entropy nitride coating on Ti alloy

High-entropy nitrides have emerged as promising alternatives to traditional protective coatings due to their excellent comprehensive properties. However, there is still a long-standing technical challenge in the design and manufacture of hard and high-temperature stable high-entropy nitride coatings. This study utilized first-principles calculations to evaluate the thermodynamic stability between high-entropy nitrides and corresponding high-entropy metals, as well as titanium alloy substrates, confirming the rationality of the structural design of the functional gradient high-entropy ceramic coating. Subsequently, a double-glow plasma surface alloying technique were conducted to prepare a CrHfNbTaTiN functional gradient high-entropy ceramic coating on titanium alloy, followed by high-temperature cyclic oxidation experiments and high-temperature ball-on-disk wear tests. The research demonstrates that the gradient composition coating exhibits strong interfacial bonding, with an adhesion strength of around 40 N. It maintains excellent oxidation resistance in environments below 700 °C and displays good high-temperature wear resistance. This study contributes to providing insights and guidance for the further development of high-temperature, high-hardness, and wear-resistant materials.

Investigation of Protective Coatings for Reducing High-Temperature Oxidation of Steels

AbstractOxidation of steel billets during pre-heating at elevated temperatures is a challenge, particularly in the forging industry. There is a need to address this problem by applying effective oxidation-resistant coatings on forging billets. In this investigation, different types of commercially available high-temperature, oxidation-resistant coatings, termed Coating A, B, C, D, E, F, and G, were applied on AISI 4340 low-alloy steel by spraying and dipping at room temperature. The oxidation protection behavior of each coating was studied over a wide range of temperatures and holding times in atmospheric conditions. The weight and height losses caused by oxidation were measured, and the samples were subsequently characterized using XRD and SEM-EDS. The protection mechanisms and anti-oxidation properties of the coatings are discussed in detail. The sample coated with Coating A showed the best protection at all temperatures compared to other coatings. The weight/height loss of Coating A-coated steel samples was reduced by 80–90% compared to an uncoated/bare sample. Coating A not only limited the outward diffusion of iron cations from the substrate but also prevented the inward diffusion of oxygen anions from the atmosphere, resulting in better oxidation resistance. The findings of the study should apply to other steels with similar compositions.

Synergistic Effect of Sn Doping in TiO2 Nanoparticles as an Additive in Anti‐Corrosion Coatings

ABSTRACTCorrosion is a major problem and protective coatings offer an effective solution. However, organic coatings are often associated with microcracks caused by the evaporation of solvents during coating preparation. This study investigates the use of titanium dioxide (TiO2) nanoparticles as a coating additive to protect mild steel surfaces. Additionally, doping TiO2 with tin (Sn) is believed to enhance its properties due to the reduced size of the nanoparticles. These nanoparticles were synthesised using the sol–gel method and subjected to various analyses. The coated mild steel samples were prepared using the dip‐coating method and immersed in 3.5 wt.% sodium chloride (NaCl) solution for 30 days. Electrochemical impedance spectroscopy (EIS) and Tafel polarisation showed that the Sn‐doped TiO2 nanoparticles as an additive improved the corrosion resistance, as evidenced by a positive shift in corrosion potential (Ecorr) and reduced corrosion current density (Icorr).

A comprehensive investigation of oxygen/graphite carbon nitride smart Nano coatings for sustainable maintenance and sacrificial anode protection of mild steel

AbstractBACKGROUNDThis study enhancing the corrosion resistance of mild steel (MS) by incorporating photo‐catalyst‐doped graphitic carbon nitride (g‐C₃N₄) nano‐sheets containing silver (Ag) and oxygen (O₂) into a solar light‐active photoelectrochemical anticorrosion paint with polyester (PE). The objective is to provide sacrificial anode protection through visible light activation.RESULTSThe developed paint forms a uniform film on the MS surface, effectively providing anodic protection under visible light. Characterization techniques, including energy‐dispersive X‐ray spectroscopy (EDX), transmission electron microscopy (TEM), Fourier‐transform infrared spectroscopy (FTIR), and UV–Vis spectroscopy, confirm the molecular structure of the nano‐sheets. Corrosion resistance, assessed through weight loss measurements and open circuit potential (OCP) tests, shows significant improvement with the addition of Ag/g‐C₃N₄ and Ag‐O₂/g‐C₃N₄ nano‐sheets at an optimized concentration of 15 mg. The protection efficiency is ranked as follows: O₂‐g/C₃N₄ > O‐g/C₃N₄ > Ag‐O₂/g‐C₃N₄ > Ag‐g/C₃N₄ > g‐C₃N₄. After 28 days of immersion in seawater, MS coated with O₂/g‐C₃N₄ exhibited the least weight loss, with an inhibition efficiency of up to 99%. Electrochemical impedance spectroscopy (EIS) further demonstrated enhanced coating resistance for the O₂/g‐C₃N₄ coating (Rct = 3.76 kΩ.cm2, Rcoat = 1.69 kΩ.cm2) compared to pure PE (Rct = 0.005 kΩ.cm2, Rcoat = 0.096 kΩ.cm2).CONCLUSIONThe synthesized O₂/g‐C₃N₄ and Ag‐O₂/g‐C₃N₄ nano‐sheets exhibit high surface areas and enhanced water dispersibility, which contribute to significant corrosion protection of MS. The electrochemical performance, including weight loss and OCP measurements, highlights the potential of these nano‐sheet photo‐catalysts in advancing corrosion resistance technologies, with broad implications for materials science and engineering applications. © 2024 Society of Chemical Industry (SCI).

Enhancing the conductivity and dispersion properties of polyaniline using ethyl orange

In our research, we developed a novel one-step synthesis method for polyaniline (PANI) using the organic dye Ethyl Orange (EO). This method facilitated the formation of PANI nanorods and significantly enhanced their electrical conductivity, achieving up to 13.5 S cm−1. The structural interaction between EO and PANI was confirmed through Fourier-transform infrared (FTIR) and UV–visible (UV-Vis) spectroscopy. Notably, the inclusion of EO improved PANI's dispersion properties, resulting in a zeta potential of 34 mV in water and excellent dispersibility in various organic solvents. These attributes significantly enhance the application potential of PANI nanorods, especially in protective coatings. Electrochemical impedance spectroscopy (EIS) analysis revealed that EO-PANI/WPU coatings (0.5 wt% EO-PANI) exhibited exceptional electrochemical stability and corrosion resistance in a 3.5 wt% NaCl solution. Specifically, the initial impedance magnitude (Zf=0.01 Hz, 1010 ohms) of EO-PANI/WPU coatings was approximately two orders of magnitude higher than that of traditional WPU coatings (108 ohms). Over time, the EO-PANI coatings demonstrated higher phase angles and impedance, indicating superior electrochemical stability and protective performance.

Diffusion nickel-cobalt coatings for protection of solid oxide electrolysis cells’ current collectors made of Crofer 22 APU steel

Diffusion nickel-cobalt coatings for protection of solid oxide electrolysis cells’ current collectors made of Crofer 22 APU steel

Protective coatings for aeroengine blade tips: a review

Protective coatings for aeroengine blade tips: a review