Protective Coatings Research Articles

Amide and amidoester fatty acid derivatives as multifunctional components of protective alkyd urethane coatings

Amide and amidoester fatty acid derivatives as multifunctional components of protective alkyd urethane coatings

Oleogel Microsphere‐Based Composite Protective Coatings with Room‐Temperature Self‐Healing Enabled by a “Soft + Hard” Hybrid Architecture (Adv. Funct. Mater. 37/2024)

Oleogel Microsphere‐Based Composite Protective Coatings with Room‐Temperature Self‐Healing Enabled by a “Soft + Hard” Hybrid Architecture (Adv. Funct. Mater. 37/2024)

Microstructural, tribological, and corrosion behavior of B4C-added TiO2 coatings applied on 316 L stainless steel via sol-gel method

Corrosion protection of metals is essential for a wide range of technological applications, and coating metal surfaces with protective materials is a commonly employed method to achieve this. Among these, TiO2 coatings are extensively used due to their excellent photocatalytic properties, their applications in sensing and solar cells, and enhancing the corrosion and wear resistance of metal surfaces. Recent advancements have focused on the incorporation of carbide particles, such as B4C, to further improve the performance of TiO2 coatings. In this study, TiO2 coatings containing 0–3.25 wt% B4C were applied to a 316 L stainless steel substrates using the sol-gel method. The coatings were characterized by XRD and SEM-EDS analyses, and their wear and corrosion properties were evaluated using ball-on-disc wear tests and corrosion tests in NaCl solutions. The results demonstrated that lower concentrations of B4C led to improved wear resistance, likely due to the formation of a durable tribolayer, while higher concentrations reduced the wear resistance, attributed to increased oxidation and the formation of brittle phases. Corrosion resistance was enhanced in coatings containing 0.25 wt% and 1.25 wt% B4C, which can be attributed to the formation of protective B2O3 phases. However, at higher B4C concentrations, the corrosion rate increased, primarily due to the presence of cracks in the coating structure. Overall, the addition of 0.25 wt% B4C to the TiO2 coating significantly improved wear and corrosion resistance, indicating its potential as an effective additive for protective coatings.

Analysis and Estimation of Atmospheric Corrosivity of Zinc Protective Coating on Steel Substrate

Analysis and Estimation of Atmospheric Corrosivity of Zinc Protective Coating on Steel Substrate

Research progress on the preparation of irradiation-resistant coating based on PVD technology

Nuclear energy is essential for the future development of countries. However, both structural and functional components of nuclear power equipment are facing severe challenges of nuclear irradiation damage after experiencing irradiation growth and irradiation creep. How to avoid irradiation damage to nuclear power equipment has become a hotspot in international research and development of surface protection technology. Deposition of protective coatings on the underlying object surface or in bulk materials has been considered as a near-term solution to enhanc functional components. Different substrate materials are selected according to other service conditions within the reactor. Suitable material selection combined with relevant optimization can significantly increase the service life of materials. This review summarizes recent research on several categories of anti-irradiation coatings prepared by physical vapor deposition technology for current industrial applications. These includes metallic, ceramic, composite and high entropy alloy coatings. The review endeavors to impart a thorough understanding of the properties of these selected anti-irradiation coatings, from the fundamental aspects of their substrate materials to their practical applications across diverse settings. It explores not only the current research progress but also the potential avenues for future advancements. Additionally, the intricate relationships between coating formulations, their resistance to irradiation, and their ultimate performance in various environments are illuminated in this paper.

Advanced eco-friendly dual-layer coating: Combining superhydrophobicity with smart self-healing for superior metal protection

In this study, a double-layer composite coating was developed by integrating a superhydrophobic top layer with a smart self-healing bottom layer. The superhydrophobic top coating demonstrated a high water contact angle of up to 153°, showcasing excellent mechanical properties, corrosion resistance, self-cleaning ability, and resistance to fouling, ice formation, and scaling. Notably, the anti-scaling property of the coating remained above 80 % after 36 h of immersion. The bottom layer, composed of waterborne epoxy resin and pH-responsive smart fillers, provided enhanced corrosion resistance and self-repairing capabilities while maintaining environmental friendliness. Experimental results indicated that the impedance value of the composite coating could reach 1010 Ω·cm2 at 0.01 Hz, significantly surpassing the corrosion resistance of traditional waterborne epoxy resin coatings. Additionally, the protective effect of the superhydrophobic top layer was evident even after the coating was damaged, suggesting a novel approach for employing superhydrophobic coatings in metal corrosion protection.

High temperature oxidation mitigation efficacy of Al2O3 and Ni-20Cr ceramic coating on boiler steel application

The primary reason of degradation and failure of many products used for high temperature applications are oxidation. Protective coatings are employed to increase the component resistance to oxidation. In the present research work, Al2O3 and Ni-20Cr were applied as coatings on SAE431 steel using a detonation gun spraying technique. At 800 °C in air with 50 cycles of heating and cooling, the oxidation behavior of uncoated and coated SAE-431 boiler steel was analyzed. Ni-20Cr coating on SAE431 boiler steel exhibits approximately 25.44 % higher oxidation resistance and the Al2O3 coating on SAE431 boiler steel exhibits approximately 32.22 % higher oxidation resistance compared to uncoated SAE431 boiler steel. After oxidation at 800 °C, the SAE431 boiler steel coated with Ni-20Cr displays prominent peaks of the Cr2O3 and Ni phases, with some minor phase of NiO. The NiO phase is observed to be less intense than Cr2O3 and Ni phases. After oxidation at 800 °C, Al2O3 coated SAE431 boiler steel exhibited strong peaks of ƞ-Al2O3 and δ-Al2O3 phases. The X-ray diffraction investigation also reveals the existence of the α-Al2O3 phase. According to our findings, based on weight change data, Ni-20Cr and Al2O3 coated boiler steel provided higher oxidation resistance than the uncoated SAE431boiler steels. The enhancement in the oxidation resistance of boiler steel can be attributed to the formation of nickel, chromium and aluminum oxide inert layer which is evident from the XRD patterns also. Exploration throughout global survey has been already done and it was found that not much work has been done on the high-temperature behavior of Ni-20Cr and Al2O3 coatings. The data obtained from the study will be helpful in examining the viability of using these coatings on boiler tubes.

Mussel-Inspired, Self-Healing, Highly Effective Fully Polymeric Fire-Retardant Coatings Enabled by Group Synergy.

Fire-retardant coatings represent a universal cost-effective approach to providing fire protection for various substrates without compromising substrates' bulk properties. However, it has been attractive yet highly challenging to create waterborne polymeric fire-retardant coatings combining high-efficiency, generally strong adhesion, and self-repairability due to a lack of rational design principles. Inspired by mussel's unique adhesive, self-healing, and char-forming mechanisms, herein, a "group synergy" design strategy is proposed to realize the combination of self-healing, strong adhesion, and high efficiency in a fully polymeric fire-retardant coating via multiple synergies between catechol, phosphonic, and hydroxyethyl groups. As-created fire-retardant coating exhibits a rapid room-temperature self-healing ability and strong adhesion to (non)polar substrates due to multiple dynamic non-covalent interactions enabled by these groups. Because these functional groups enable the formation of a robust structurally intact yet slightly expanded char layer upon exposure to flame, a 200µm-thick such coating can make extremely flammable polystyrene foam very difficult to ignite and self-extinguishing, which far outperforms previous strategies. Moreover, this coating can provide universal exceptional fire protection for a variety of substrates from polymer foams, and timber, to fabric and steel. This work presents a promising material design principle to create next-generation sustainable high-performance fire-retardant coatings for general fire protection.

Geometric modelling of corrosion inhibitor pigments in active protective coatings based on SR-nano-CT images

This paper reports on an essential step towards accelerating the development of new, environmentally friendly active protective coatings by structure optimization. The complex microstructure of the pigment particles within a coating have been observed non-destructively in 3D by nano-computed tomography using synchrotron radiation. For the first time, a stochastic geometry model is fitted based on spatial geometric features of the particles observed in the 3D images. The typical cell of a random Gibbs-Laguerre tessellation is used to model the particles' polyhedral shapes as well as the observed joint size and aspect ratio distributions.

Novel high-entropy perovskite titanate: A potential thermal protective material with improved thermophysical properties

High-entropy oxides (HEOs) have attracted considerable attention as potential materials for thermal protective coatings, which are driven by the growing demand for critical high-temperature components. Solid-phase reaction was used in the successful synthesis of Nonisotropic high-entropy titanate (La0.3K0.1Ca0.2Sr0.2Ba0.2)TiO3+δ thermal protective coating (TPC) material, whose mechanical and thermal properties were investigated via combined first-principles calculations and experimental methods. Notably, the coating material exhibited a higher thermal expansion coefficient (TEC) of 12.2 × 10−6 K−1 compared with other HEOs reported in the TPC field. Meanwhile, the prepared TPC material presented a prominent thermal insulation behavior with a low thermal conductivity of 1.46W·m−1·K−1 at 1200 °C, and this condition was mainly attributed to multicomponent cation doping, which produces prevalent structural defects and lattice distortions that greatly enhance phonon scattering. First-principles calculations revealed the outstanding elastic anisotropy of (La0.3K0.1Ca0.2Sr0.2Ba0.2)TiO3+δ and its stronger resistance to microcrack extension compared with its single-component counterpart. The compound also showed good mechanical properties with a Vickers hardness of 11.5GPa. The extraordinary thermo-mechanical properties achieved serve as a strong motivation for the pursuit of high-entropy approaches for the development of promising high-temperature TPC.

Effect of chemical inhomogeneity on the structure and properties of the two-layer TiAl-based coating obtained by non-vacuum electron beam cladding: Experimental investigations and density functional theory simulations

Non-vacuum electron beam cladding is a highly effective technology for producing protective coatings on metal workpieces. In this study, the 3.8 mm thick TiAl-based coating with Cr and Nb additions was obtained on the Ti alloy substrate in two passes of the electron beam. To evaluate inhomogeneity of the two-layer coating, energy-dispersive synchrotron X-ray diffraction (EDSXRD) in combination with energy-dispersive X-ray spectroscopy (EDX) was applied. It was found that in the direction from the top of the coating to the substrate, the dilution of the cladding layers with Ti increased. It influenced the phase constitution of the coating and led to a variation in the chemical composition of different phases (α2-Ti3Al, β-phase, and TiN). The properties of the first (lower) and the second (upper) cladding layers were evaluated separately. The upper layer exhibited greater oxidation resistance than the lower one due to the presence of the γ-phase, which has superior high-temperature stability compared to the α2-Ti3Al phase, predominant in the coating. The influence of varying chemical composition on the oxidation resistance was also estimated using density functional theory (DFT) simulations. It was found that decrease in Al content in the α2 phase leads to an increase in oxygen absorption energy. This could potentially result in a decrease in oxidation resistance. Wear resistance of the first and the second cladding layers was at the same level mainly due to the low contribution of minor phases. Additionally, DFT simulations show that the variations in chemical composition of the major phase (Ti3Al) are not likely to impact the coating wear resistance.

Preparation, microstructure and properties of Yb2O3-x optical hydrophobic films for infrared windows

In order to improve the adaptability of infrared windows in harsh wet environments, Yb2O3-x films were prepared by ion assisted reactive thermal evaporating deposition. The surface morphology, microstructure, composition, optical properties, hardness, residual stress and hydrophobicity of Yb2O3-x films were comprehensively characterized. The effects of the oxygen flow rate on the properties of the Yb2O3-x films had been explored. It is found that the root-mean-square roughness of the films increases as the flow rate increases from 10 sccm to 35 sccm. The crystallization characteristics are closely related to the oxygen flow rate, and the film prepared at 15 sccm exhibits the best crystallinity. X-ray photoelectron spectroscopy (XPS) testing shows that the ratio of Yb to lattice oxygen decreases, while the content of trivalent Yb ions in the film increases with increasing oxygen flow rate. Thin film prepared at lowest oxygen flow rate exhibits highest optical absorption, which is related to oxygen defects in the films. Moreover, films prepared at 15 sccm, 25 sccm and 35 sccm show good transparency in the long-wave infrared band. The hardness of the film prepared at 15 sccm is about 9 GPa. Due to change in density of the thin film, the compressive stress of the film decreases with increase of oxygen flow rate. The hydrophobicity of the film is affected by the surface chemical composition and surface roughness, and the maximum water contact angle is 100°. In a word, the Yb2O3-x films are found to be excellent hydrophobic protective coatings for infrared windows.

Long-term superhydrophobic, antibacterial, and corrosion-resistant Ag-loaded LiAl-LDH composite coating grown in-situ on MAO coating

This study successfully prepared long-term superhydrophobic, antibacterial, and corrosion-resistant lithium aluminum layered double hydroxide (LiAl-LDH) modified with 1H,1H,2H,2H-perfluorooctyltriethoxysilane (PFOTES) through a hydrothermal reaction. The LiAl-LDH was in situ grown on the micro-arc oxidation (MAO) film and loaded with Ag nanoparticles. The results showed that at a hydrothermal reaction temperature of 150 °C, LiAl-LDH effectively filled the microscopic defects of the MAO coating, significantly enhancing its hydrophobicity. After PFOTES treatment, the water contact angle remained above 150° even after 75 days of immersion in simulated seawater. Additionally, the introduction of Ag+ notably improved the antibacterial properties of the coating. Electrochemical tests indicated that the corrosion resistance of the coating increased with higher hydrothermal temperatures. The corrosion current density of the coating obtained at 150 °C was measured at 2.30 × 10−9 A∙cm−2, which is two orders of magnitude lower than that obtained at 100 °C. Following hydrophobic modification, the corrosion current density decreased further, and after 50 days of immersion in simulated seawater, the |Z|0.01Hz value remained above 108 Ω·cm2, demonstrating excellent corrosion resistance. This study provides important experimental and theoretical foundations for developing metal surface protective coatings with broad application prospects.

Fabrication of large frame zincophilic bimetallic compounds as protective coatings for highly efficient Zn metal anodes

Abstract The integration of an artificial protective coating into the Zn metal anode is considered as a highly efficient approach to minimize growth of Zn dendrites. The present study involves the design and synthesis of NiCo nanomaterials featuring a three-dimensional (3D) open structure and an abundance of active groups on their surface. Subsequently, NiCo nanomaterials are applied as a protective coating onto Zn foil to safeguard the Zn anode. The NiCo protective coating provides a rich zincophilic site, thus enhancing the stability of the electrode and effectively inhibiting Zn dendrite growth. Hence, the NiCo@Zn\\|NiCo@Zn symmetric cell with a lifespan up to 950 h at a current density of 2 mA cm−2. When paired with NH4V4O10, the full battery exhibits satisfied ultra-long cycle stability, maintaining good capacity retention after 3000 cycles at 10 A g−1. This work provides a new idea for the practical application of zinc ion batteries.

An Analytical Review on the Degradation Mechanisms and Magnesium Alloy Protective Coatings in Biomedical Applications

An Analytical Review on the Degradation Mechanisms and Magnesium Alloy Protective Coatings in Biomedical Applications

Optimization strategies for graphene-based protection coatings: a review

Abstract Graphene has become an emerging and promising option in the field of protection coating for anti-corrosion due to its specific properties in chemical inertia and physical impermeability. It can be applied to metal protection coating in forms of either atomically thin films or composite materials, known, respectively, as pure chemical vapour deposition (CVD) graphene coatings and graphene composite coatings (GCCs). Nonetheless, various structure defects, synthesis imperfections and graphene’s positive potential to metals would make graphene-based protective coatings tend to exhibit corrosion promotion by arousing micro-galvanic corrosion, largely undermining its anti-corrosion efficiency. Based on this, many optimization strategies and methods have been conceived and applied to the graphene-based protection coatings in these two aspects for improving its anti-corrosion efficiency. For example, a good dispersion and orderly arrangement of graphene derivatives in the GCCs can largely optimize its anti-corrosion performance. Here, this paper separately reviews detailed optimization strategies, corresponding mechanisms and key factors for the use of representative graphene-based materials in these two aspects, with the aim of providing comprehensive knowledge and a roadmap of developing cheap, powerful and effective barrier technologies. Finally, perspectives on opportunities and challenges in improving the barrier coating efficiency of graphene-based materials are discussed.

Properties and Applications of Supersaturated Metastable Alloys Obtained via Electrodeposition

Supersaturated alloys can exhibit superior properties and electrodeposition is a cost-effective and versatile technique to produce them. In this review, the chemical, mechanical and structural properties of supersaturated alloys are discussed, and connections with metallic glasses and high entropy alloys are also exposed. After discussing mechanisms causing supersaturation in electrodeposited alloys, an overview of the most important electrodeposited metastable alloys is provided, showing that they are mainly used as protective coatings able to improve corrosion resistance and tribological performance of a large variety of industrial components. Composition of the electrolytic baths and deposition parameters are also considered and discussed.

Thermodynamic properties, interfacial adhesion energy and tribological properties between MCN (M = Hf, Ta, Cr, Nb) coating and Ti alloy substrates investigated by experiment and first-principles calculations

A series of MCN (M = Hf, Ta, Cr, Nb) coatings were prepared by double glow plasma surface alloying (DGPSA) as protective hard coatings for Ti60 (Ti-5.5Al-4.0Zr-4.0Sn), aiming to solve the problems of low bonding strength between the ceramic coating and the substrate as well as the poor wear resistant of ceramic alloy coatings. First principles calculation was used to study the elastic constant of MC0.5N0.5 solids, thermomechanical parameters and the interfacial adhesive strength of Ti(101)/MCN(220). The calculated results indicated the HfCN solids show excellent mechanical properties, lower thermal expansion coefficient α, lower Gibbbs values and higher values of entropy (S), superior adhesion strength Wad ∼ 5.7 J/m2. The high-temperature tribological performance tests show that the HfCN and TaCN coatings exhibited better wear resistance compared with the CrCN and NbCN coatings at 500 °C -700 °C. The wear rate of HfCN coatings at 500 °C and 700 °C is about 2 times and 5 times lower than that of CrCN, which is in accordance with the HfCN coating’s excellent thermal stability and high interfacial bonding strength with the Ti substrate. The adhesion wear mechanism of all coatings gradually intensified with increasing temperature.

Physical aging of a glassy polymer in cultural heritage conservation

AbstractArtworks, particularly easel paintings, are multi‐component materials intended to last indefinitely. The protective coatings applied to these artworks often consist of amorphous glass‐like polymers, which undergo slow physical aging and structural recovery below their glass transition temperature. This process alters key physical properties such as mechanical strength, optical clarity, and thermal stability over extended periods. This study investigates the time‐dependent evolution of these properties in Laropal A81, a widely used synthetic resin for cultural heritage conservation, particularly as a replacement for ancient varnishes. The investigation involves characterization of enthalpy recovery via differential scanning calorimetry, refractive index evolution via refractometry, and creep compliance evolution via rheological measurements. The aging behavior of Laropal A81 is further analyzed using the Kohlrausch–Williams–Watts function and the Tool–Narayanaswamy–Moynihan model, enabling the quantification of critical dynamic parameters such as activation energy, nonlinearity, partition coefficients, and non‐exponentiality. The gained insights into the long‐term behavior of this coating's properties can be valuable for improving preservation and restoration strategies for cultural heritage.

Information-bibliographical service of scientific and technical problem of „Application of protective coatings as well as protective and decorative metal coatings"

The article is devoted to the analysis of information models dealing with the problem of the application of protective coatings as well as protective and decorative metal coatings. Results of investigations reveal the subject structure of the problem, display the core of scientific and industrial journals, and define bibliographical manuals and databases. Based on the developed models, a structure for a problem-oriented data bank is suggested.