Papers by Keyword: Coating

Abstract: This study examines the fabrication and performance of hydrophobic copper and nickel foams produced via a two-step immersion coating method using silver nitrate and stearic acid, targeting oil–water separation and corrosion protection in marine-related environments. In both substrates, silver deposition generated hierarchical surface roughness, while stearic acid functionalization reduced surface energy. Surface morphology and coating integrity were analyzed using scanning electron microscopy (SEM), and wettability was evaluated through water contact angle measurements. Copper foams exhibited water contact angles approaching 180°, demonstrated improved coating adhesion and separation efficiency remained above 95 % over repeated use. Copper-based superhydrophobic foams also showed excellent thermal and chemical stability, maintaining hydrophobicity after prolonged exposure to harsh conditions. Nickel foams developed a strongly adhered hydrophobic silver coating with water contact angles of approximately 147°. The coatings maintained high hydrophobicity across a wide temperature range and exhibited excellent reusability, achieving oil–water separation efficiencies higher than 95 % after multiple cycles. Potentiodynamic polarization was employed to evaluate corrosion behavior of both coated substrates in 3.5 % NaCl solution. Overall, the results indicate that while the same coating effectively provides hydrophobicity and durability to both copper and nickel foams, differences in wettability and coating stability are determined by their intrinsic microstructures.

Abstract: Hot stamping of manganese–boron steels is widely used in automotive manufacturing to produce ultra-high-strength components with tensile strengths exceeding 1500 MPa . Conventional industrial heating relies on gas-fired roller hearth furnaces, which require 5 – 10 min to reach austenitization and exhibit low energy efficiency . Resistance heating offers a compact and energy-efficient alternative, enabling heating rates above 100 K/s and full austenitization within seconds. However, rapid heating of uncoated steels leads to severe oxidation, and established coating systems such as AlSi are not designed for diffusion-controlled bonding within such short times . This study demonstrates that resistance heating in an XHV-adequate atmosphere – consisting of nitrogen and monosilane – suppresses oxidation while simultaneously enabling adhesion of a pre-laminated aluminum foil to the steel substrate. For coating preparation, 22MnB5 sheets were roughened by corundum blasting, cleaned, and laminated with an aluminum foil using a flat-die pressing tool. The pre-coated blanks were heated in a self-developed resistance-heating chamber, in which the oxygen concentration was reduced to an XHV-adequate level. Several heating profiles were investigated to determine suitable process windows for coating formation. The results show that resistance heating achieves austenitization within a few seconds, reducing heating times by more than an order of magnitude compared to furnace heating. The XHV-adequate atmosphere reliably prevents scale formation, enabling completely oxidation-free surfaces during rapid heating. Under these conditions, the laminated aluminum foil bonds uniformly to the substrate, forming a continuous coating layer. Metallographic cross-sections and SEM analyses confirm the formation of Al–Fe intermetallic phases at the interface, demonstrating robust metallurgical bonding suitable for subsequent hot stamping operations. Overall, the combination of resistance rapid heating and an XHV-adequate atmosphere provides a highly energy-efficient process route for hot stamping while offering an opportunity to integrate aluminum-based protective coatings directly into the heating step. This approach addresses the limitations of current furnace-based heating and coating technologies and opens a promising pathway toward more flexible, sustainable, and functionally integrated hot-stamping process chains.

Abstract: This research is centered on an environmentally sustainable sol-gel coating, using silica extracted from rice husk ash (RHA), to foster the persistent deterioration of mild steel cause by corrosion for decades despite all efforts put in place by previous researchers. The research focus, was on the extraction of silica from rice hush to synthesize silica-base sol-gel formulation, doped in a graphene oxide to enhanced its efficiency. The formulated sol-gel coating was applied on the mild steel substrates and then characterized by evaluating its corrosion resistance through electrochemical and surface characterization techniques. Such as XRD, FT-IR, SEM, Tafel Polarization and Adhesion Test, which were carried out on the coated samples. Corrosion test was carried out by immersing coated and uncoated samples in 3.5% NaCl solution for seven (7) days and then conducted a Potentiodynamic polarization and Electrical Impedance Spectroscopy (EIS) test to analyze the corrosion rates, impedance and protection efficiency. It was observed that, the highest inhibition efficiency of 85% was achieved at a concentration of 1.0g/200ml after 7 days of exposure which revealed that, coated mild steel possess higher potential corrosion resistant when compared with the conventional anti-corrosion coating in use. Essentially, this research would definitely promote green chemistry by utilizing agricultural waste materials, avoiding uses of toxic precursors and offering an eco-friendly alternative to conventional anti-corrosion coatings.

Abstract: This study evaluates the effect of a starch-calcium carbonate coating on the quality of paper produced from empty fruit bunches (EFB) of oil palm. The primary objective is to assess the changes in water absorbance of the paper before and after the coating process. Samples of EFB paper were coated and subsequently tested using a Cobb tester to measure their water absorbance. The results indicate that the coating application significantly reduced the paper’ water absorbance. These findings suggest that a starch-calcium carbonate coating can improve the quality of paper made from agricultural waste. The implications of this research may lead to new opportunities for utilizing agro-industrial waste in the paper manufacturing industry.

Abstract: Imidazole is an aromatic and alkaloid diazole that shows prominent anticancer properties. Regulating the imidazole compound into nano-drugs in the size range 10-200 nm enhances the effectiveness of imidazole as an anti-cancer agent, thus enhancing therapeutic potential. In this study, imidazole nano drug dispersion was prepared using the re-precipitation method. The dispersion of various imidazole derivative compounds, namely 4-(4,5-diphenyl-1H-imidazol-2-yl)-2-methoxyphenol (Vanilin), 2-(4-Methoxyphenyl)-4,5-diphenyl-1H-imidazole (O-Me), 2,4,5-Triphenylimidazole (Benzaldehid) and 2-(4-nitrophenyl)-4,5-diphenyl-1H-imidazole (Nitro) were screened. The dispersion stability was evaluated in a mimic biological environment using phosphate buffer saline (PBS) for 24 hours, and the size of the nanodrugs was determined. The results showed that 4-(4,5-diphenyl-1H-imidazol-2-yl)-2-methoxyphenol had the best size of 203 nm, and no aggregation was observed even after 24h. This result indicates that 4-(4,5-diphenyl-1H-imidazol-2-yl)-2-methoxyphenol (Vanilin) meets the requirement of enhanced permeability retention (EPR) effect and is a prominent candidate as an effective anti-cancer agent.

Abstract: Desalination plays a crucial role in addressing global water scarcity by providing a reliable source of freshwater from seawater and brackish water, supporting both human consumption and industrial needs. Feed spacers are an essential component of membrane systems, enhancing mixing and mass transfer. However, they also facilitate foulant deposition, with biofouling often initiating on the spacer surface before spreading to the membrane. Biofouling poses a significant challenge as it is difficult to remove once occurred. In response, extensive research has explored modifying feed spacer surfaces to mitigate fouling. Despite advancements, the use of hazardous chemical reagents in conventional spacer coatings raises serious environmental concerns, including contamination of the food chain and potential risks to human health. This review focuses on eco-friendly spacer coating strategies for biofouling resistance, emphasizing sustainable methods to address the environmental impacts of traditional approaches. Techniques such as plasma pretreatment, direct coating, oil-infused coatings, and candle-soot coatings have shown potential in reducing biofouling by modifying surface properties, including hydrophilicity, hydrophobicity, and biocidal characteristics. These methods have proven effective in mitigating membrane fouling, thereby improving the performance and lifespan of membrane systems. Finally, the paper outlines future research directions, including experimental and numerical approaches, to enhance spacer coatings for antifouling in membrane applications.

Abstract: Along with the rapid development of technology in this modern era, batteries have a significant role, used as energy storage devices. Lithium-ion batteries have reliable characteristics as energy sources for electronic devices and electric vehicles. Nickel Manganese Cobalt (NMC) is claimed to be the best cathode for high-energy-density lithium-ion batteries. This study aims to analyze the effect of the addition of TiO₂ nanoparticles as a coating material with variations of 1, 3, and 5 wt.% on the morphology and electrochemical performance of LiNi_0.9Mn_0.05Co_0.05O₂ (NMC 955). The coating process with the addition of TiO₂ through ball milling method at a speed of 600 rpm for 1 minute and 1000 rpm for 60 minutes. The results obtained are an increase in particle diameter in the 5 wt.% variation with particle size in the range from 0.1 to 0.5 μm. NMC 955 TiO₂ 1% has the highest specific capacity of 168 mAh g^-1 at 0.5 C. It is indicated that the process of adding TiO₂ coating on NMC 955, can improve the electrochemical performance in terms of specific capacity compared to NMC 955 without TiO₂ coating.

Abstract: Nowadays, researchers are trying to understand whether geopolymers have the potential to be used as a coating material, particularly for protecting metal from corrosion attack. This study aimed to evaluate the effectiveness of fly ash-based geopolymer coatings in protecting steel by immersing the coated samples in a 3.5 wt% NaCl solution for immersion periods of 1, 7, 14, and 28 days. The uncoated steel showed the NaCl color changed to yellowish and became darker with increasing immersion time, indicating severe corrosion on the uncoated steel after 28 days. Surprisingly, with 3mm geopolymer thickness coated on the steel, NaCl solution remain unchanged until 28 days immersion period. The corrosion rate exhibits a very gradual increase, with only 0.112 mm/year recorded after 28 days of immersion. No defects such as blistering, peeling, or cracking were observed on the coated steel. These results indicate that geopolymer holds considerable promise as a coating material, warranting further investigation for its potential applications in this area.

Abstract: Carbon steel is widely used in infrastructure, manufacturing, and structures due to its cost-effectiveness and robust mechanical properties. However, the susceptibility of steel structures to corrosion in various working environments has been a longstanding concern. In this study, we explored the potential of titanium-aluminum (Ti-Al) coating as a surface treatment to enhance the corrosion resistance of low-carbon steel. The coating was applied using the arc spraying technique, where two materials were melted by an arc and then distributed onto the substrate using compressed air. To evaluate the corrosion resistance of the coated samples, we conducted immersion tests following the ASTM G31 standard for durations of 625 and 1000 hours. Additionally, electrochemical technique was employed to assess the anti-corrosion performance of both the Ti-Al coating and the substrate. Surface characterization was carried out using scanning electron microscopy equipped with energy-dispersive X-ray spectroscopy (SEM-EDX), as well as measurements of hardness and roughness. The SEM-EDX analysis revealed uniform distribution of titanium and aluminum across the surface and within the coating. Moreover, the coating significantly altered the surface roughness. Electrochemical corrosion testing indicated that the Ti-Al coating exhibited lower corrosion current and corrosion potential, suggesting its potential to enhance the corrosion resistance of the substrate. The SEM-EDX revealed cracks on the coating surface and the oxidation level of the coating surface varied with immersion time. The hardness of the coating was found to be relatively lower than that of the substrate, while the surface roughness was higher. Overall, the findings suggest that Ti-Al coating holds promise for enhancing the corrosion resistance of steel structures, as evidenced by its low corrosion current density and corrosion potential in corrosive environments.

Abstract: The surface wettability of metallic biomaterials significantly influences the biological response of biomedical implants. However, the optimal degree of wettability depends on the specific coating or surface treatment applied to the biomaterial. Researchers have widely utilised hydroxyapatite coatings to modify implant surfaces to enhance bioactivity, biocompatibility, and osseointegration. This review article discussed the impact of hydroxyapatite-doped coatings on the surface wettability of metallic biomaterials. A systematic search of Scopus and Web of Science databases was conducted to review recent studies investigating the wettability and biological response of hydroxyapatite-doped coatings applied through standard implant surface deposition techniques. Results reveal that hydroxyapatite-doped coatings are typically hydrophilic and have higher surface energy than uncoated hydrophobic metallic surfaces. The hydrophilic nature promotes better interaction with biological fluids, resulting in cell adhesion and proliferation. The rough and porous surface increases wettability as fluid can easily penetrate the craters. Further research may elucidate the complex connectivity of deposition method process parameters with surface wettability and biological outcomes. This review briefly overviews current research on hydroxyapatite-doped coatings and their effects on surface wettability and biointegration.