Journal of Coatings Technology and Research最新文献

In this work, the wear resistance of the linear low-density polyethylene polymer (LLDPE) is enhanced by incorporating copper (Cu) and bronze powders into thin composite coatings. These coatings are applied separately to the LLDPE substrate using an ecologically friendly elaboration methodology. Digital image processing methodology indicates better homogeneity of LLDPE/Cu coatings when compared to the LLDPE/bronze coatings. Mechanical characterizations of the coating film show a significant increase in the tensile elastic modulus, tensile yield strength, and Vickers microhardness as the filler content increases. Reciprocating friction tests against high-chromium steel ball indicate that the friction coefficient of LLDPE/Cu composite coatings (with a 20% weight fraction) decreases by 24% compared to pure LLDPE, providing the best friction results. Bronze coatings show superior wear resistance with an optimum filler reinforcement equal to 10 wt%. An increase in the friction and wear performances of LLDPE/Cu coatings is associated with the ability of copper atoms in enhancing the adhesion of the transfer film to the steel counterface, preventing its direct contact with the coating. The transfer film is less coherent than that obtained with LLDPE/Cu coatings due to the spherical shape of bronze particles, which could act as bearing and roll inside the wear track.

The microporosity of micro-arc oxidation (MAO) coatings hindered their application on magnesium alloys. Here, the polysilazane (PSZ) was used to seal the pores of MAO coatings by spraying, creating a corrosion-resistant MAO/PSZ composite coating on AZ31B Mg alloy. The active groups (Si–N) in the PSZ layer hydrolyzed in the presence of moisture and they typically cured at elevated temperatures to form a solid ceramic layer. Its morphology, hydrophobicity, corrosion resistance and other properties were studied in detail. The PSZ formed a hydrophobic pore-sealing layer on the MAO layer with high bond strength. Moreover, the self-corrosion current density of the coating was significantly reduced (2.95 × 10^–5 μA/cm²), indicating enhancement of the corrosion protection ability. This is attributed to the dense and strong Si–O pore-sealing layer formed by the PSZ polymer on MAO.

Space exploration has burgeoned into a billion-dollar industry, pushing the boundaries of human knowledge in various fields. The prospect of space stations being accessible to part of the population by the end of the century is within reach. However, the bacterial ecology in these stations poses a significant threat, as the hostile environment may increase the mutation rate, potentially leading to new pandemics upon return to Earth. One proposed mitigation strategy is the development of bactericidal surfaces that prevent bacteria from adhering and promote their inactivation. Bioinspired approaches offer promising solutions given their efficiency, cost-effectiveness, and environmental friendliness. This paper conducts a comprehensive literature review on bacteria in the space environment, using the International Space Station as a reference. In addition to presenting a brief overview of various bactericidal coating strategies currently studied or employed, three specific production approaches are examined in more detail: antimicrobial peptide coatings, quaternary ammonium compound coatings, and nanostructured surfaces that promote bacterial lysis. The study concludes that while antimicrobial peptides are susceptible to radiation and quaternary ammonium compounds raise concerns about genotoxicity, nanostructured surfaces emerge as a robust solution due to their structural stability and immense potential for applications in the aerospace industry.

Zn/Al-LDHs were firstly synthesized, and then, NO₂^- ions were exchanged into the interlayers of LDHs. The sustained release of NO₂^- ions from the ({text{NO}}_{2}^{ - })-modified LDHs was confirmed in the simulated concrete pore solution. The ({text{NO}}_{2}^{ - })-modified LDHs, acting as nanoreservoirs, were incorporated into an epoxy coating. The nanocomposite coating exhibits more durable corrosion protection for the steel substrate in comparison with the undoped coating in the simulated concrete pore solution. The improvement of corrosion resistance is attributed to the sustained release of ({text{NO}}_{2}^{ - }) ions with strong passivation ability from the nanoreservoirs. The excess incorporation of the nanoreservoirs is adverse to the corrosion protection of the nanocomposite coating. In addition, the self-repairing performance can be observed for the scribed nanocomposite coating in the simulated concrete pore solution.

UV-curable epoxy acrylic resin (EA) has been widely used due to its high hardness, good thermal stability, and low cost. However, EA has some disadvantages including poor flexibility and low impact resistance, which limit the application field of EA resin. Herein, the modified EA resin (REA) was synthesized by modifying bisphenol A epoxy resin (E51) with esterification products of cyclic anhydride (RAH) and 2-hydroxyethyl acrylate (HEA). The effects of anhydride categories on REA properties including mechanical properties, thermostability, gel content, and comprehensive properties were studied. It was found that UV-cured REA resin formed by the anhydride carrying benzene ring or C=C double bond exhibited high gel contents, high tensile stresses (40 MPa), high pencil hardness (H), and excellent water resistance. As the carbon chain of the anhydride increased, the viscosity of the modified resin product decreased sharply, the elongation at break and the thermal stability of the cured resin were improved, and the flexibility and the impact resistance of the cured film were enhanced. In order to combine the advantages of a flexible long chain and rigid benzene ring, REA was modified by chemical blending of glutaric anhydride (GAH) and phthalic anhydride (PAH). When the GAH/PAH molar ratio was 0.3:0.7, the UV-cured film exhibited better impact resistance (35 cm·kg) and flexibility (1 mm) compared with EA, as well as excellent water resistance and ethanol resistance. The results provide theoretical guidance for the design and synthesis of high-performance UV-curable resins.

Urea-formaldehyde resins, which are often used indoors as coatings or adhesives due to their limited resistance to moisture, are becoming less and less important, particularly due to the increasingly strict limit values for formaldehyde.¹ The release of toxicologically harmful formaldehyde is possible even after curing, so that these resins, which have been favored in terms of price, are increasingly being substituted.² This work focused on the synthesis of formaldehyde-free coating materials based on higher aldehydes, which can be cured with urea or urea derivatives. The substitution of formaldehyde, which is becoming more and more restricted, also makes it easier to produce and handle these resins on an industrial scale. Especially higher aldehydes of the benzaldehyde type were investigated, as these do not mechanistically release formaldehyde during the curing reaction with urea and are also unable to form colored enamides.³ Both aspects were confirmed in this work. The crosslinking mechanism was investigated using spectroscopic methods such as IR or Raman, and the mechanical properties of the resulting coatings were examined using DMA and rheometer-DMTA. Furthermore, application tests in accordance with DIN were carried out. Especially adducts from renewable 5-hydroxymetylfurfural turned out to form high performance coatings when crosslinked with urea.

The increasing severity of electromagnetic pollution has prompted the development of various conductive polymer composite materials for electromagnetic protection in recent years. However, research specifically focused on conductive polymer composite coatings remains limited. In this study, we prepared two types of conductive coatings, which are designated as UP and UC coatings, using waterborne polyurethane (WPU) combined with polyaniline (PANI) or multi-walled carbon nanotubes (MWCNT) through a standard preparation method involving paint formulation and air spraying. We conducted a thorough evaluation and comparison of the performance of these coatings. Both UP and UC coatings exhibited commendable mechanical properties, including adhesion, impact strength, and hardness. Notably, the UC coatings demonstrated higher conductivity and electromagnetic interference (EMI) shielding capabilities compared to the UP coatings. Specifically, the UP-20 coating achieved a high conductivity of 97.79 S m⁻¹, a moderate total shielding effectiveness (SE_T) of 7.47 dB, and an impressive specific shielding effectiveness (SSE) of 983.7 dB cm² g⁻¹ at 8.2 GHz. Overall, the UP coatings show significant potential and advantages for everyday applications in electromagnetic protection.

This study presents the development of a multifunctional nanocomposite coating aimed at enhancing the efficiency of solar panels through self-cleaning and cooling properties. The novel coating integrates nanosized zinc oxide (ZnO), silicon dioxide (SiO₂), and chlorophyll to address two significant challenges: dust accumulation and thermal management. The results showed that the ZnO coating exhibits the highest visible light transmittance (96.38%), while the combined coating containing ZnO, SiO₂, and chlorophyll achieves a balanced transmittance of 93.48%. In terms of UV absorption, chlorophyll significantly enhances the coating's ability to protect underlying materials from UV damage, complemented by ZnO's protective qualities. Furthermore, the coating's thermal emissivity is optimized, with the combined formulation showing the highest emissivity, indicating superior heat management capabilities. Contact angle measurements reveal that the multifunctional coating exhibits hydrophobic properties, contributing to effective self-cleaning by minimizing dust accumulation—evident over a 7-day assessment period. Performance testing indicates that the coated panels demonstrate up to 22.12% improvement in power output and notable cooling enhancements, with surface temperatures decreasing by up to 9.62%. These findings suggest that the proposed nanocomposite coating not only improves energy efficiency by minimizing maintenance needs but also advances the sustainability of solar energy technologies, making it a promising solution for photovoltaic applications, particularly in dust-prone environments. Further research will focus on optimizing the coating's formulation and exploring its long-term performance in real-world conditions.

Based on its characteristics, gangue, which contains stabilized silica and aluminum oxide, is suitable for preparing high-temperature-resistant materials. Geopolymer (GP) derived from gangue (CG) is characterized by a three-dimensional mesh structure and used as a filler in water-based intumescent fireproofing coatings, which improves the fire performance of the coatings and, to a certain extent, also alleviates the environmental problems caused by the large number of outputs of CG, and plays the role of turning waste into treasure. Experimental tests showed that the fireproof coating with 4% GP showed excellent high-temperature fire retardant properties, and the maximum expansion factor was 16.3, and the minimum backsheet temperature was 256.4°C by simulating the large-board method. The addition of GP with three-dimensional mesh structure enhances the densification of the coating and delays the burning time of the coating, which is delayed by 10 s compared with that of the coating without GP. In addition, it also reduces the generation of CO, has less heat release and better thermal stability, which can be confirmed by the cone calorimeter test and thermogravimetric (TG) analysis. The limiting oxygen index (LOI) of the coating with the addition of 4% GP is 60.2%, which is much higher than that of the flame retardant standard (27%). The results of these tests show the coating’s excellent ability to form a protective barrier, limit heat transfer and delay the decomposition process.

Marine biofouling has caused huge economic and energy losses, and the application of marine antifouling coatings is one of the effective solutions to this problem. Sily-acrylate based self-polishing coatings are favored because of excellent antifouling performance. However, weak static antifouling performance restricts the development of sily-acrylate based antifouling coatings. To solve this problem, an eugenol ester-based sily-acrylate polymer (EMSPs) is synthesised, which showed both self-polishing and antifouling performance. The highest content of eugenol (EMSP-16) inhibits Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) up to 62.2% and 76.3%, respectively, and inhibits the adhesion of Halamphora sp. and Nitzschia closterium (N. closterium) up to 85.1% and 90.8%, respectively. Mussel adhesion experiments show that mussels tend to avoid coatings with high eugenol content. The eugenol ester-based sily-acrylate polymer provides a new way to develop new environmentally friendly marine antifouling coatings and alleviate heavy metal pollution in the marine environment.