Commercial Coatings Research Articles

Enhanced superhydrophobicity of acrylic polyurethane coatings by femtosecond laser ablation

In recent years, superhydrophobic coatings on aircraft surfaces have garnered significant attention due to their ability to protect the surface from corrosive source like raindrops, sand, and gasoline, etc. However, to date, research on enhancing the hydrophobicity of commercial aviation coatings on aircraft Al surface is still insufficient. In the present study, the femtosecond laser ablation technique is used to texture acrylic polyurethane coatings (denoted as APU) which has been used in the aviation field to achieve a superhydrophobic surface. The relationship between micro-/nanostructures fabricated on the coatings under different laser processing parameters and the corresponding hydrophobicity was studied. The microcone-structured superhydrophobic APU surface prepared under the optimal parameters exhibited a contact angle of 151.2° and a sliding angle of 4.2°. Durability test results show that the APU surface remains at a contact angle of more than 150° after a 140° high-temperature test and 6 h acid-base solution immersion, indicating good chemical and thermal stability. The adopted femtosecond laser fabrication technology and the resultant superhydrophobic coating in the present study may have potential applications to protect aircraft parts from corrosion damage.

Preparation of SiO2 solvent-free nanofluids for modification of commercial corrosion-resistant coatings

Preparation of SiO2 solvent-free nanofluids for modification of commercial corrosion-resistant coatings

Citral-thymol based synergistic shellac coatings enhanced shelf life of Kinnow fruit stored under low temperature conditions

Microbial spoilage incurs the main cause of reduced shelf life of Kinnow during storage and transportation. This study aimed to evaluate the postharvest application of plant-derived citral and thymol-based shellac wax coatings on ‘Kinnow’ mandarin under controlled conditions (5–7 °C, 90–95 % relative humidity (RH)) over a 75-day storage period. The fruit were coated with shellac wax (SH) supplemented with citral (1.0 %, CSH), thymol (1.0 %, TSH) and citral-thymol combined formulation (1.0 %, CTSH (1:1)). Rheology studies revealed that the Herschel–Bulkley model was the best fit for all coating solutions, ensuring desirable spreadability and adhesion. The CTSH-coating outperformed all other treatments by reducing mean spoilage to 0.46% as compared to commercial shellac (6.71%) over a period of 75 days under cold store conditions. The treated fruit could control the physiological weight loss to 5.73 % as compared to commercial SH coatings (7.62 %) for 60 days. The study concluded that CTSH-coated Kinnow fruit can be stored up to 60 days under cold store conditions at 5–7 °C and 90–95 % RH with acceptable fruit quality (sensory score 7.83). The activities of cell wall degrading enzymes such as Pectin methylesterase (PME) and cellulase were also found to be retarded, contributing to prolonged shelf life. Therefore, these coatings may offer a green substitute to the synthetic analogues, with no health side effects for extending the postharvest shelf life of Kinnow up to 60 days under cold store conditions.

Enhancing anticorrosion performance of metals by incorporating cellulose nanofibrils/α-ZrP composite as nanofiller into water-based coating

The anticorrosion of metals has gain considerable interest in view of economic and environmental issues. Coating protection is one of the most effective and cost-effective methods for anticorrosion of metals. However, the traditional coatings often suffer from many issues such as poor performance or high cost. For the first time, a strategy was proposed by constructing cellulose nanofibrils (CNF)/alpha‑zirconium phosphate (α-ZrP) composite as nanofiller and incorporating into water-based coatings for anticorrosion of metals. The successful coordination of α-ZrP nanosheet and CNF were characterized. The effects of the resultant composite on anticorrosion performance were investigated. The results showed that, the as-prepared coating exhibited superior anticorrosion performance to commercial coatings. The impedance of the test sample coated with the as-prepared coating reached up to 4.38 × 105 Ω when it was immersed in 3.5 % NaCl solution with few corrosions fragmentation on metal surface, exhibiting a favorable long-term anticorrosion performance. Meanwhile, the anticorrosion mechanism was proposed. It is expected that this strategy would provide novel solutions for developing highly efficient water-based anticorrosive coatings of metals.

Tunable distributed Bragg reflector developed by magnetron sputtering to improve the power conversion efficiency of transparent IR cells for solar energy harvesting applications

Transparent organic photovoltaic (TOPV) cells integrated into windows are key to reducing the carbon dioxide emissions associated with the building sector. However, TOPV cells that reach a compromise between efficiency and transparency must still be developed. In addition, to implement this technology in glass production companies, the materials and processes used in TOPV cell development must be compatible with producing these devices on an industrial scale. Here, an infrared (IR) cell combining a PC60BM-based active material, ITO/ZnO as the back transparent electrode, PEDOT:PSS and ITO or Ag as the top transparent electrode, and a DBR as an antireflective coating was developed and applied on 625 mm2 glass samples. The structure of the DBR based on titanium dioxide (TiO2) and silicon dioxide (SiO2) monolayers was adjusted to the IR cell absorption spectra to reach a power conversion efficiency (PCE) of 5 and 4.3, and an average visible transmission (AVT) of 41 % and 51 % for ITO and Ag top electrodes, respectively. The manufacturing route of these devices involved commercial polymers and coatings that can be deposited by technologies already applied in the glass industry, such as magnetron sputtering or thermal evaporation. Therefore, the IR cells developed here showed a good compromise between efficiency, transparency, and large-scale production manufacturability.

Effect of Deposition Parameters on Micromechanical Properties and Machining Performance of CrN Coating for Wet Finish Turning of Ti6Al4V Alloy.

This study aims to optimize the performance of CrN coatings deposited on WC cutting tools for machining Ti6Al4V alloy, where the formation of built-up edge (BUE) is a prevalent and critical issue. In-house CrN coatings were developed using the PVD (Physical Vapor Deposition) process, with variations in deposition parameters including nitrogen gas pressure, bias voltage, and coating thickness. A comprehensive experimental approach encompassing deposition, characterization, and machining performance evaluation was employed to identify the optimal deposition conditions. The results indicated that CrN coatings deposited at a nitrogen gas pressure of 4 Pa, a bias voltage of -50 V, and a thickness of 1.81 µm exhibited superior performance, significantly reducing BUE formation and tool wear. These optimized coatings demonstrated enhanced properties, such as a higher elastic modulus and a lower coefficient of friction, which contributed to improved tool life and machining performance. Comparative studies with commercial CrN coatings revealed that the in-house developed coatings outperformed the commercial variants by approximately 65% in tool life, owing to their superior mechanical properties and reduced friction. This research highlights the potential of tailored CrN coatings for advanced machining applications and emphasizes the importance of optimizing deposition parameters to achieve high-performance tool coatings.

Emissions of Oxygenated Volatile Organic Compounds and Their Roles in Ozone Formation in Beijing

Oxygenated volatile organic compound (OVOC) emissions play a critical role in tropospheric ozone (O3) formation. This paper aims to establish an emission inventory and source profile database for OVOCs in Beijing, utilizing revised and reconstructed data from field measurements and existing literature. The study also assesses their potential impact on the O3 base on the ozone formation potential (OFP). Results indicate that OVOC emissions in Beijing predominantly originate from natural and residential sources, encompassing commercial solvent usage, cooking, residential combustion, construction adhesives, and construction coatings. OVOCs contributed 5.6% to OFP, which is significantly less than their emission contribution of 20.1%. Major OFP contributors include plant sources (26.2%), commercial solvent use (21.0%), cooking (20.5%), and construction adhesives (8.4%). The primary OVOC species contributing to OFP for OVOCs are acetaldehyde, methanol, hexanal, ethanol, and acetone, collectively contributing 59.0% of the total OFP. Natural sources exhibit significant seasonal variability, particularly in summer when plant emissions peak, constituting 78.9% of annual emissions and significantly impacting summer ozone pollution (OFP of 13,954 t). Conversely, emissions from other OVOC sources remain relatively stable year-round. Thus, strategies to mitigate summer ozone pollution in Beijing should prioritize plant sources while comprehensively addressing residential sources in other seasons. District-specific annual OVOC emissions are from Fangshan (3967 t), Changping (3958 t), Daxing (3853 t), and Chaoyang (3616 t), which reflect year-round forested areas in these regions and high populations.

Surface Characteristics and Artificial Weathering Resistance of Oil-Based Coatings on the Chemically and Thermally Modified Short-Rotation Teak Wood.

Improving the durability of short-rotation wood can be achieved through chemical and thermal modification. Chemical and thermal modification can have an impact on the physicochemical properties of wood, which can affect wood's surface characteristics and its resistance to weathering. The purpose of this study was to investigate the surface characteristics and artificial weathering resistance of chemically and thermally modified short-rotation teak wood coated with linseed oil (LO)-, tung oil (TO)-, and commercial oil-based coatings consisting of a mixture of linseed oil and tung oil (LT) and commercial oil-based polyurethane resin (LB) coatings. The short-rotation teak woods were prepared in untreated and treated with furfuryl alcohol (FA), thermal treatment (HT) at 150 and 220 °C, and combination of glycerol-maleic anhydride (GMA) impregnation with thermal treatment at 150 and 220 °C. The surface characteristics measured were surface free energy, wettability, Persoz hardness, bonding quality, and color changes before and after artificial weathering exposure. The results showed that chemical and thermal modifications treatment tended to reduce total surface free energy (SFE), hardness, wettability, and bonding quality. FA and GMA at 220 °C treatments provided homogenization effect on surface characteristics, especially in total SFE and wettability. The total SFE of untreated wood ranged from 45.00 to 51.13 mN/m, and treated wood ranged from 40.58 to 50.79 mN/m. The wettability of oil-based coating according to K-value ranged from 0.20 to 0.54. TO presented better photostability than LO. Short-rotation teak wood coated with oil-based commercial coatings presented better weathering resistance compared to pure natural drying oil. Commercial oil-based coatings provided better weathering protection for the chemically and thermally modified teak wood. The application of oil-based coatings on chemically and thermally modified short-rotation teak is being considered for the development of a better wood-protection system.

Removal of graffiti paint from construction materials coated with TiO2-based photocatalysts.

Graffiti on construction materials has significant social and economic impacts, especially on artistic and historical artefacts. Anti-graffiti protective coatings are used to generate low surface energies that limit graffiti adhesion to the surface, thereby reducing surface damage and facilitating removal. The anti-graffiti properties of three commercial TiO2-based coatings were tested under outdoor exposure conditions using four colours of graffiti paint (red, blue, black, and white). Chemical removers were used to clean the stained surfaces to understand the impact of the photocatalytic coatings during the conventional cleaning procedure. The effectiveness of cleaning was assessed by visual observations, colour measurements, and the percentage of residual stain. The anti-graffiti efficacy was strongly dependent on the colour of the graffiti and characteristics of the TiO2 coating. The cleaning performance of TiO2-treated samples was likely related to the photocatalytic redox reactions that decompose the graffiti. Additionally, their hydrophilicity may also prevent the adhesion and/or penetration of graffiti paint on the surface and/or pore matrix.

Engineering of dual recognition functional aptamer-molecularly imprinted polymeric solid-phase microextraction for detecting of 17β-estradiol in meat samples

In this study, an enhanced selective recognition strategy was employed to construct a novel solid-phase microextraction fiber coating for the detection of 17β-estradiol, characterized by the combination of aptamer biorecognition and molecularly imprinted polymer recognition. Benefiting from the combination of molecularly imprinted and aptamer, aptamer-molecularly imprinted (Apt-MIP) fiber coating had synergistic recognition effect. The effects of pH, ion concentration, extraction time, desorption time and desorption solvent on the adsorption capacity of Apt-MIP were investigated. The adsorption of 17β-estradiol on Apt-MIP followed pseudo-second order kinetic model, and the Freundlich isotherm. The process was exothermic and thermodynamically spontaneous. Compared with polymers that only rely on imprinted recognition, non-imprinted recognition or aptamer affinity, Apt-MIP had the best recognition performance, which was 1.30–2.20 times that of these three materials. Furthermore, the adsorption capacity of Apt-MIP for 17β-estradiol was 885.36–1487.52 times than that of polyacrylate and polydimethylsiloxane/divinylbenzone commercial fiber coatings. Apt-MIP fiber coating had good stability and could be reused for more than 15 times. Apt-MIP solid-phase microextraction coupled with high-performance liquid chromatography was successfully applied to the determination of 17β-estradiol in pork, chicken, fish and shrimp samples, with satisfactory recoveries of 79.61 %–105.70 % and low limits of detection (0.03 μg/kg). This work provides new perspectives and strategies for sample pretreatment techniques based on molecular imprinting technology and improves analytical performance.

Optimization of the Application of Commercial Hydrophobic Coatings for Natural Stone Protection and Preservation

Natural stone has been used worldwide in the construction of archaeological and historical heritage. However, its preservation continues to be threatened by weathering and degradation phenomena. Water is widely recognized as the most threatening external component that contributes to stone deterioration, increasing the need for the development of protective hydrophobic coatings to eliminate water penetration. This study intends to contribute to the better understanding of natural stone treatment strategies to prevent water penetration and subsequent stone alteration by studying the effect of coating and stone substrate temperatures, and the number of coating applications, on the effectiveness, compatibility, and durability of commercial hydrophobic coatings. The results obtained revealed that while more than one application increases coating hydrophobic effectiveness, it frequently leads to changes in the aesthetic appearance of natural stone, including whitening and darkening of the substrate’s original hues. Improved hydrophobic effectiveness (maximum gain of ≈ 9%) is also achieved when applying the commercial coatings at 4 °C to natural stone substrates maintained at room temperature, conditions that are feasible to be used in real life. Additionally, the commercial coating composed of silane/siloxane with modified fluorinated additives was found to be the most effective and durable hydrophobic solution.

Environmental Impact Assessment of Anti-Corrosion Coating Life Cycle Processes for Marine Applications

In the present study, the life cycle assessment (LCA) of uncoated steel and alkyd-coated steel (using the sol–gel method) systems subjected to the marine atmosphere is performed to examine their environmental impacts. The LCA findings demonstrate a notable 46% reduction in the overall environmental impact of the coated system compared to the uncoated system. The findings of the sensitivity analysis indicate that a decreased mean time between repair and maintenance, along with an augmented quantity of coating, results in adverse environmental consequences. Furthermore, the LCA outcomes highlight the significant environmental impacts associated with 3-glycidyloxypropyltrimethoxysilane and n-propanol within the coated system. Hence, there is a need for the development of commercial coatings with bio-based products to develop a greener solution.

One-step spraying of protein-anchored chitosan oligosaccharide antimicrobial coating for food preservation

The persistent global issues of unsafe food and food waste continue to exist. Microbial contamination stands out as a major cause of losses in perishable foods like vegetables and fruits. Herein, we report a self-assembling coating based on disulfide bond cleavage-induced bovine serum albumin (BSA), where the antimicrobial activity of chitosan oligosaccharide (COS) is stably anchored in the coating by electrostatic interactions during the unfolding-aggregation phase of BSA. The intrinsic antimicrobial activity of COS, combined with the positively charged and hydrophobic regions enriched on the BSA coating, significantly disrupts the integrity of bacterial structures. Furthermore, the BSA@COS coating can easily adhere in situ to the grooves on the surface of strawberries through a simple one-step spraying process, extending the shelf life of strawberries and bananas by nearly three times. This makes it a potential economic alternative to current commercial antimicrobial coatings, offering a solution to the rampant global issue of food waste.

Development of inorganic anticorrosive coatings for steel bars: Corrosion resistance testing and design

A densely structured three-dimensional geopolymer network could effectively impede the migration and diffusion of chloride ion. This study developed one kind of efficient and cost-effective and multi-component geopolymer coating (MGC) for inhibiting and delaying the corrosion of steel. The influence of alkali content, metakaolin replacement ratio, polyvinyl alcohol content, and titanium dioxide content on the fluidity, setting time, and rheological properties of MGC was investigated. Accelerated corrosion tests were carried out to determine the optimal formulation of MGC. The corrosion resistance of MGC prepared by different coating method was compared to commercial organic metal coatings, for which the salt spray test, adhesion test, and electrochemical impedance spectroscopy test were conducted. The results showed that the dip-coated specimen of MGC exhibited 63.8% decrease in mass loss, 59.5% decrease in adhesive strength loss, and 38.1% increase in impedance modulus compared to commercial organic metal coatings. Furthermore, the corrosion protection mechanism of MGC was elucidated by analyzing its microstructural characteristics including the functional groups formed on the surface of coated steel bars. In terms of cost, MGC reduced the total cost by about 15 times compared to commercial organic metal coatings.

Development of a Simple Setup to Measure Shielding Effectiveness at Microwave Frequencies.

Testing the shielding effectiveness of materials is a key step for many applications, from the industrial to the biomedical field. This task is very relevant for high-sensitivity sensors, whose performance can be greatly affected by electromagnetic fields. However, the available testing procedures often require expensive, bulky, and heavy measurement chambers. In this paper, a cost-effective and reliable measurement procedure for testing the shielding effectiveness of materials is proposed. It exploits a lab-scale anechoic shielded chamber, which is lightweight, compact, and cost-effective if compared to the available commercial solutions. The measurement procedure employs a vector network analyzer to allow an accurate and fast characterization setup. The chamber realization phases and the measurement procedure are described. The shielding capability of the chamber is measured up to 26 GHz, whereas the performance of commercial shielding coatings is tested to demonstrate the measurement's effectiveness.

Processability and Separability of Commercial Anti-Corrosion Coatings Produced by In Situ Hydrogen-Processing of Magnetic Scrap (HPMS) Recycling of NdFeB.

The recycling of NdFeB magnets is necessary to ensure a reliable and ethical supply of rare earth elements as critical raw materials. This has been recognized internationally, prompting the implementation of large-scale legislative measured aimed at its resolution; for example, an ambitious recycling quote has been established in the Critical Raw Materials Act Successful recycling in sufficient quantities is challenged by product designs that do not allow the extraction and recycling of these high-performance permanent magnets without excessive effort and cost. This is particularly true for smaller motors using NdFeB magnets. Therefore, methods of recycling such arrangements with little or no dismantling are being researched. They are tested for the hydrogen-processing of magnetic scrap (HPMS) method, a short-loop mechanical recycling process. As contamination of the recycled material with residues of anti-corrosion coatings, adhesives, etc., may lead to downcycling, the separability of such residues from bulk magnets and magnet powder is explored. It is found that the hydrogen permeability, expansion volume, and the chosen coating affect the viable preparation and separation methods as recyclability-relevant design features.

Zwitterionic Hydrogel Coating with Antisediment Properties for Marine Antifouling Applications.

Biofouling is a serious issue affecting the marine industry because the attached micro- and macrocontaminants can increase fuel consumption and damage ship hulls. A hydrophilic hydrogel-based coating is considered a promising antifouling material because it is environmentally friendly and the dense hydration layer can protect the substrate from microbial attachment. However, sediment adsorption can be an issue for hydrogel-based coatings. Their natural soft and porous structures can trap sediment from the marine environment and weaken the antifouling capability. There is still little research on the antisediment properties of hydrogels, and none of them deal with this problem. Here, we report on optimizing zwitterionic hydrogel-based coatings to improve their antisediment properties and achieve comparable performance to commercial biocidal coatings, which are the gold standard in the antifouling coating area. After 1 week of sediment contamination and 2 weeks of diatom coculturing, this optimized zwitterionic hydrogel coating maintained its antifouling properties with a few diatoms on the surface. Its large-scale samples also achieved antifouling performance similar to that of biocidal coatings in the Atlantic Ocean for 1.5 months. More importantly, our research provides a universal strategy to improve the antisediment properties of soft hydrogel-based coatings. For the first time, we report that the introduction of interfacial electrostatic interactions enhanced the antisediment properties of hydrogels.

The Response of Naturally Based Coatings and Citrus Fungicides to the Development of Four Postharvest Fungi.

The tomato (Licopersicon esculentum Mill.) is considered to be one of the products with the highest demand due to its nutritional value; however, it is susceptible to infection by fungi during its pre- and postharvest stages. In this research, three commercial products (1% Citrocover, 1% Citro 80, and 0.002% Microdyn) and two coatings based on 1.0% chitosan/0.1% lime or 0.1% orange essential oils were evaluated in vitro and on Saladette tomatoes that were previously inoculated with four postharvest fungi. The application of the commercial citrus-based product Citrocover was highly effective in reducing the in vitro development of Aspergillus flavus, Fusarium oxysporum, and Colletotrichum gloeosporioides, but not Rhizopus stolonifer. The sanitizer Microdyn promoted infections with most fungi. Citrus-based products were effective in reducing infections with A. flavus in the tomatoes during storage. Overall, mycotoxin production was very low for all treatments. The use of commercial citrus-based products and coatings did not alter the weight loss, firmness, or total soluble solid contents of the treated tomatoes. The changes observed were, rather, associated with the normal ripening process of Saladette tomatoes. The commercial citrus-based products satisfactorily controlled the in vitro growth of the fungi Aspergillus flavus, Fusarium oxysporum, and Colletotrichum gloeosporioides.

Environmental friendly multifunctional orange pigment for cool coating applications

The present study illustrates the development of an environmentally benign intense orange inorganic pigment, by substituting Si4+ metal ion at the Bi3+ site of Bi4V2O11 via solid-state method. The partial replacement of Si4+, induced a strain in the crystal lattice of the compound, which resulted in a substantial improvement in the visible light reflectance. A reduction in oxygen deficiency in the lattice structure facilitated the colour tuning of the pigment series from brownish red to orange and then on to yellowish orange. The composition Bi3.8Si0.2V2O11+δ exhibited a bright orange hue with colour co-ordinates a* = 39, b* = 34 and L* = 52. Furthermore, NIR solar reflectance of the pigment was 86%, which is superior than the reported and commercial orange pigments. Compared to commercial pigment coatings, Bi3.8Si0.2V2O11+δ achieved a temperature reduction of 2 °C inside a foam model house. An exceptional corrosion resistance of 1.6 × 1010 Ωcm2, was registered by the pigment loaded epoxy coating with good stability. The corrosion inhibition mechanism of the pigment operates through the hand in hand working of passive Bi-O and Si-O, active FeOOH and vanadate moiety. On the whole, the new multifunctional orange pigment has the potential to be a viable replacement for the toxic commercial pigments in the market.

Absorption of volatile organic compounds (VOCs) by polymer tubing: implications for indoor air and use as a simple gas-phase volatility separation technique

Abstract. Previous studies have demonstrated volatility-dependent absorption of gas-phase volatile organic compounds (VOCs) to Teflon and other polymers. Polymer–VOC interactions are relevant for atmospheric chemistry sampling, as gas–wall partitioning in polymer tubing can cause delays and biases during measurements. They are also relevant to the study of indoor chemistry, where polymer-based materials are abundant (e.g., carpets and paints). In this work, we quantify the absorptive capacities of multiple tubing materials, including four nonconductive polymers (important for gas sampling and indoor air quality), four electrically conductive polymers and two commercial steel coatings (for gas and particle sampling). We compare their performance to previously characterized materials. To quantify the absorptive capacities, we expose the tubing to a series of ketones in the volatility range 104–109 µg m−3 and monitor transmission. For slow-diffusion polymers (e.g., perfluoroalkoxy alkane (PFA) Teflon and nylon), absorption is limited to a thin surface layer, and a single-layer absorption model can fit the data well. For fast-diffusion polymers (e.g., polyethylene and conductive silicone), a larger depth of the polymer is available for diffusion, and a multilayer absorption model is needed. The multilayer model allows fitting solid-phase diffusion coefficients for different materials, which range from 4×10-9 to 4×10-7 cm2 s−1. These diffusion coefficients are ∼ 8 orders of magnitude larger than literature values for fluorinated ethylene propylene (FEP) Teflon film. This enormous difference explains the differences in VOC absorption measured here. We fit an equivalent absorptive mass (CW, µg m−3) for each absorptive material. We found PFA to be the least absorptive, with CW ∼ 105 µg m−3, and conductive silicone to be the most absorptive, with CW ∼ 1013 µg m−3. PFA transmits VOCs easily and intermediate-volatility species (IVOCs) with quantifiable delays. In contrast, conductive silicone tubing transmits only the most volatile VOCs, denuding all lower-volatility species. Semi-volatile species (SVOCs) are very difficult to sample quantitatively through any tubing material. We demonstrate a system combining several slow- and fast-diffusion tubing materials that can be used to separate a mixture of VOCs into volatility classes. New conductive silicone tubing contaminated the gas stream with siloxanes, but this effect was reduced 10 000-fold for aged tubing, while maintaining the same absorptive properties. SilcoNert (tested in this work) and Silonite (tested in previous work) steel coatings showed gas transmission that was almost as good as PFA, but since they undergo adsorption, their delay times may be humidity- and concentration-dependent.