Search Results (112)

This work investigates on how Fe incorporation influences the surface, microstructural, and optical properties of solution precursor plasma-sprayed TiO₂ coatings. The Fe-TiO₂ coatings were prepared using titanium isopropoxide and iron acetylacetonate as precursors, with ethanol as the solvent. X-ray diffraction analysis revealed the existence of both anatase and rutile TiO₂ phases, with a predominant rutile phase, also confirmed by Raman spectroscopy. There was an increase in the anatase crystals upon the addition of Fe ions. A longer spray distance further enhanced the anatase content and reduced the average TiO₂ crystallite sizes present in the Fe-added coatings. SEM cross-sectional images displayed finely grained, densely packed deposits in the Fe-added coatings. UV-Vis spectroscopy showed visible-light absorption by the Fe-TiO₂ coatings, with reduced band gap energies ranging from 2.846 ± 0.002 eV to 2.936 ± 0.003 eV. Photoluminescence analysis showed reduced emission intensity at 356 nm (3.48 eV) for the Fe-TiO₂ coatings. These findings confirm solution precursor plasma spray to be an effective method for developing Fe-TiO₂ coatings with potential application as visible-light-active photocatalysts. Full article

Swimming goggles still face numerous challenges in practical use, including deterioration and failure of anti-fog coatings, residual water marks on lens surfaces, and relatively short service life in complex environments. When swimming outdoors during winter, goggles also present an icing problem. To address these problems and enhance the performance of swimming goggles, this study employs a combination of plasma cleaning and mechanical spraying methods, utilizing HB-139 SiO₂ to modify the surface of goggle lenses, thereby fabricating lenses with superhydrophobic properties. The changes in lens surfaces before and after friction and immersion treatments were characterized using three-dimensional profilometry and scanning electron microscopy, further investigating the hydrophobic, drag-reducing, wear-resistant, and anti-icing properties of the lenses. Experimental results demonstrate that SiO₂ can enhance the hydrophobic, drag-reducing, durability, and anti-icing performance of the lenses. Under standard conditions, the contact angle of modified samples reached 162.33 ± 3.15°, representing a 48.77 ± 2.15% improvement over original samples. Under friction conditions, modified samples exhibited a 45.86 ± 2.53% increase in contact angle compared to original samples, with Sa values decreasing by 58.64 ± 3.21%. Under immersion conditions, modified samples showed a 54.37 ± 2.44% increase in contact angle relative to original samples. The modified samples demonstrated excellent droplet bouncing performance at temperatures of −10 °C, 10 °C, and 30 °C. De-icing efficiency improved by 14.94 ± 2.37%. Throughout the experimental process, SiO₂ demonstrated exceptional hydrophobic, drag-reducing, durability, and anti-icing capabilities. This establishes a robust foundation for the exemplary performance of swimming goggles in both training and competitive contexts. Full article

Ice accumulation poses a significant hazard to aviation safety, particularly in cold weather conditions, as it can compromise aerodynamic performance, increase structural weight, and diminish lift, occasionally resulting in severe stall incidents. At present, such risks are managed through the use of energy-demanding active ice protection systems (IPSs), which operate either by inhibiting ice formation (anti-icing) or by removing existing ice (de-icing). Nonetheless, in the context of future sustainable aviation, there is a pressing need to develop IPSs with lower energy requirements. A promising approach involves hybrid IPSs that integrate conventional active systems with passive superhydrophobic or icephobic surface treatments, which are capable of preventing, delaying, or minimizing ice buildup. These systems offer the potential to substantially decrease the energy consumption and consequently the CO₂ emissions. Furthermore, in accordance with FAA regulations, active IPSs are not permitted to operate during takeoff and initial flight stages to prevent any reduction in engine thrust. These two reasons emphasize the critical importance of developing efficient coatings that, on the one hand, promote the mobility of water droplets, hereby preventing ice formation, as achieved by superhydrophobic surfaces, and on the other hand, facilitate ice detachment, as required for icephobic performance. In this context, the primary objective of the present work is to emphasize the icephobic properties of two superhydrophobic coatings. To achieve this, an extensive characterization is first conducted, including wettability, Surface Free Energy (SFE), and surface roughness, to confirm their superhydrophobic nature. This is followed by an assessment of their icephobic performance, specifically in terms of ice adhesion strength, with comparisons made against a commercial aeronautical coating. The results revealed a significant reduction in both the wettability and SFE of the developed coatings compared to the reference, along with a marked decrease in ice adhesion strength, thereby demonstrating their icephobic properties. Future activities will focus on the combination of coatings with active IPS in order to assess the energy efficiency under extensive icing conditions where both superhydrophobic and icephobic properties are required. Full article

Anti-icing and de-icing technologies are crucial in modern aviation, with optimising ice adhesion performance on material surfaces being a key challenge. This study proposes a straightforward method for fabricating hydrophobic silicone rubber surfaces using a mesh to construct microstructures. The influence of microstructure size and anisotropy on surface wettability and ice adhesion performance is systematically investigated. The experimental results demonstrate that introducing microstructures significantly enhances the hydrophobicity of silicone rubber surfaces, achieving a maximum static contact angle of 149.3 ± 1.3°. For microstructures with identical shapes, dimensional variations affect surface roughness and functional performance. Although the structure with the most significant dimension (600#-SR) exhibits the highest surface roughness, smaller structures (e.g., 1400#-SR) demonstrate superior hydrophobicity and lower ice adhesion strength, likely due to enhanced air entrapment and reduced effective solid–liquid and solid–ice contact areas. Furthermore, due to anisotropic microstructures, a marked directional difference in ice adhesion strength is observed: the lowest strength in the X direction is 38.6 kPa, compared to 63.3 kPa in the Y direction. Fine-tuning the size and configuration of microstructures effectively minimises the ice adhesion strength and enables targeted optimisation of surface properties. This research offers theoretical support for developing innovative, energy-efficient materials with superior anti-icing properties and provides new insights for crafting solutions tailored to various anti-icing needs. Full article

Airfoils are widely used in the fields of aviation and wind power generation. Icing changes the profile of an airfoil and degrades its aerodynamic performance. Therefore, it is necessary to explore the icing of airfoils and the adhesive characteristics of the ice formed in order to explore their de-icing. In the present study, this is accomplished for the NACA0018 and S809 airfoils through measurement of the areas, thicknesses, and adhesive strength of the ice formed under different wind speeds. The iced area increased linearly with the icing time. The area on the S809 airfoil covered with ice was larger than that on the NACA0018 airfoil because of the maximum thickness of the airfoil profile, the distribution of surface pressures, and the flow state of the air. The effects of wind speed on the adhesive strengths of the ice formed on both airfoils were then explored. The adhesive strength of ice on the NACA0018 airfoil increased with the wind speed, while the wind speed had a minor effect on the ice on the S809 airfoil. These findings provide a foundation for the in-depth exploration of de-icing technology. Full article

Al-Li alloys have been widely applied in aircraft structural component and shell material. However, Al-Li alloys are prone to corrosion failure, which leads to a considerable safety risk in the aerospace field and greatly limits their industrial application. Herein, a simple, low-cost, and large-scale air-spraying technique is developed for the preparation of an alumina-based ceramics coating with enhanced corrosion resistance and anti-icing behavior. The results show that the static contact angle of the as-prepared coating is 157.2 ± 0.4°, and the rolling angle is only 9.8°, suggesting a super-hydrophobic surface. Meanwhile, the electrochemical corrosion potential of the coating is 70 mV higher than that of the substrate, and the corrosion current density of the coating also decreases by 1 order of magnitude, indicating a significantly improved corrosion resistance. In addition, the fabricated super-hydrophobic coating also shows excellent anti-pollution and anti-icing characteristics. This work provides positive guidance for expanding the application of hydrophobic coating in the aerospace industry, especially in some complex corrosion, icing, and pollution environments. Full article

During continuous casting, coated slag is applied to molten steel to enhance heat transfer and lubrication. In this study, a numerical calculation model was built to reveal the flowing characteristic of slag according to the fundamental principles of heat transfer and viscous fluid mechanics. The flow and heat transfer behaviour of protective slag on the surface of molten steel and the flow velocity of liquid slag in slag channel gaps were calculated and analyzed. The streaming and thermal conduction situation of slag on the surface of molten steel, as well as the flow velocity of liquid flux in the slag passage gap, were calculated and analyzed. The results showed that as the thickness of the liquidus slag film increased from 10 to 12 mm, the thermal flux density at the top of the flux film layer decreased from 0.1059 to 0.0882 MW/m². The heat flux density increased rapidly within 0.1 m of the narrow side of the mould, reaching a peak value of 2.27 MW/m². As the viscosity temperature factor of the flux increased from 0.45 to 2.05, the maximum floating speed of the liquid film from the water inlet to the narrow side in the centre district of the mould decreased from 0.0316 to 0.028 m/s, representing a reduction of approximately 11.4%. This study can provide a reference for the design and improvement of protective slag. Full article

Cadmium-based coatings have long been used to protect high-strength steel in aerospace, but due to cadmium’s toxic and carcinogenic nature, its use is increasingly restricted. Zinc–nickel coatings, containing 10–14 wt% Ni, offer superior corrosion resistance compared to pure zinc, making them a promising alternative. However, Zn–Ni coatings are prone to cracking, which can compromise their protection. This study investigates how different anode materials influence crack formation and coating properties during electrodeposition. Zinc and nickel anodes produced coatings with consistent thicknesses of 13–15 µm, while 1020 steel and stainless steel resulted in thicker coatings of up to 33 µm. Notably, coatings deposited with nickel anodes demonstrated strong adhesion and consistent interface quality. Zinc anodes achieved a high Ni content of about 13.5 wt%, whereas 1020 steel and stainless steel produced lower Ni content, around 7 wt%. Additionally, zinc and nickel anodes led to fewer defects and minimal porosity, in contrast to the higher porosity observed with 1020 steel and stainless steel anodes. Furthermore, zinc anodes maintained stable voltages (~0.5 V), contributing to more uniform coatings. In terms of corrosion resistance, zinc anodes exhibited a lower corrosion rate of 0.44 mm/year compared to 1.54 mm/year for nickel anodes. This study highlights the importance of anode selection in reducing cracking and optimizing Zn–Ni coatings, presenting them as a safer and more effective alternative to cadmium-based coatings. Full article

Ice accumulation poses considerable challenges in transportation, notably in the domain of general aviation. The present study combines the strengths and limitations of conventional aircraft deicing techniques with the emerging trend toward all-electric aircraft. This study aims to utilize laser-induced graphene (LIG) technology to create a multifunctional surface, seamlessly integrating hydrophobic properties with efficient electrical heating to mitigate surface icing effectively. We investigated the utilization of a 10.6 μm CO₂ laser for direct writing on polyimide (PI), a widely used insulating encapsulation material. From the thermomechanical perspective, our initial analysis using COMSOL Multiphysics software (V5.6) revealed that when the laser power P exceeds 5 W, the PI substrate experiences ablative damage. The experimental results show that when P ≤ 5 W, an increase in power has a positive impact on the quality, surface porosity, roughness reduction, line-spacing reduction, and water contact-angle enhancement of the graphene. Conversely, when P > 5 W, higher power negatively affects both the substrate and the graphene structure by inducing excessive ablation. However, it influences the graphene line height positively and is consistent with overall experimental–simulation congruence. Furthermore, the incorporation of high-quality graphene resulted in a surface that exhibited higher contact angles (CA > 120°), lower energy consumption, and higher heating efficiency compared to the use of traditional electrically heated materials for anti-icing applications. The potential applications of this one-step fabrication method extend across various industries, particularly aviation, marine engineering, and other ice-prone domains. Moreover, the method has extensive prospects for addressing pivotal challenges associated with ice formation and serves as an innovative and efficient anti-icing technology. Full article

The present work is aimed at the development of superhydrophobic coatings and surfaces with enhanced robustness and boiling temperature resistance. We will address the synthesis method of the coatings, which was based on the preparation of a composite of silanized diatomite particles embedded in epoxy resin. After the synthesis of the composite solution, it was applied by dip-coating in stainless steel substrates and submitted to a post-treatment cure in an oven. The method proved to be a comparatively fast and simple one. Then, the substrate/coating sets were characterized using different techniques, including Fourier transform infrared spectroscopy and scanning electron microscopy, and their water contact angle and roughness were measured. Apart from this, the physical and chemical robustness of the sets was also tested using diverse resistance tests like adhesion strength, abrasion resistance, resistance to strong acids and bases, and resistance to boiling water. The main results are that we obtained robust coatings, with wettability defined by water contact angles above 150°. Also, the synthesized coatings revealed good resistance to boiling water, as their properties were almost unchanged after the completion of a long period of tests. The characterization of the produced coatings suggested their propensity to be explored for use in water boiling surfaces and interfaces for cooling purposes in boiling heat transfer systems. Full article

The liquid phase projection diagram, three-dimensional phase diagram, and vertical section diagram of the Zn–x%Al–x%Mg alloy system was calculated using the phase diagram calculation software Pandat. Simultaneously making full use of the self-developed hot-dip galvanizing process simulation machine by China Steel Research produced a 75%Zn–19%Al–6%Mg coating. A method combining phase diagram calculations and experimental verification was used to investigate the equilibrium phases and solidification process of the alloy. The microstructure of the 75%Zn–19%Al–6%Mg coating was studied using scanning electron microscopy and energy dispersive spectrometry. The results indicate that the coating structure consists of primary Al dendrite phase, MgZn₂ inter-metallic compound and Zn-rich phase. There is no ternary eutectic structure in the coating structure. Al dendrites grow on the surface of the coating, while there are no Al dendrites on the cross-section. The experimental results strongly concur with the calculated results from the Pandat phase diagram. The solidification sequence of the 75%Zn–19%Al–6%Mg coating is L→L + Al→L + Al + MgZn₂→Al + MgZn₂ + Zn. The phase diagram guides industrial production significantly, avoiding the waste of transitional materials and zinc caused by small scale trial and error experiments, thus reducing unnecessary production costs. The factory can select a reasonable coating composition designing scheme in the phase diagram, based on the performance requirements of customers for the coating. Full article

New biodegradable paper-based films are a hot research topic in the development of green agriculture. In this study, a black paper-based film coated with cooked tung oil with excellent mechanical properties, a hydrophobic surface, high heat transfer and strong weather resistance was prepared by spraying high-pigment carbon black solution on the surface of base paper. The results showed that the surface-solidified oil film had a rough structure produced via the brush coating process using cooked tung oil. The base film of the black paper had a given hydrophobic structure, and the contact angle reached 98.9°. Cooked tung oil permeates into the inside of the paper base, and after curing, it forms a multi-dimensional network film structure. The maximum tensile stress of the black paper base film is about 123% higher than that of the original paper base film. The coloring of carbon black gives the black paper base film a heat conduction effect, and the average heat transfer rate reaches 15.12 °C/s. Cooked tung oil is combined with the paper-based fiber high-toughness layer to form a stable system. The existence of a cured film improves the basic mechanics and hydrophobicity, and the resistance to ultraviolet radiation and hot air is greatly improved. This study provides a feasible scheme for the application of a black paper base film coated with cooked tung oil. Full article

Coating technology, as a common coating method, is widely used in many industrial fields, among which the mattress industry utilizes it to bond sponges to produce foam mattresses. The thickness of the coating on the sponge is crucial to the quality and performance of the mattress. Hence, this study took the CNCHK-10 high-performance intelligent sponge roller coating as a model; simulated the roller coating process under different viscosities and linear speeds using fluid simulation; analyzed the effects of different viscosities of the coating liquid and the linear speeds of the rollers on the thickness of the coating; and derived the relationships between the viscosity of the coating liquid and the linear speed of the rollers and the thickness of the coating. The relationship between the viscosity of the coating liquid and the linear speed of the roller and coating thickness was obtained. The results show that in the viscosity range of the glue, the viscosity is 1.5 Pa·s when the coating thickness is the smallest, and, at this time, the amount of glue is about 74.1927 g/m²; in the adjustment range of the roller linear speed, the linear speed is 20 m/min when the coating thickness is the smallest, and, at this time, the amount of glue is about 74.1931 g/m². The results of the study can be used for determining the coating process parameters for a reasonable selection and control to provide a theoretical basis. Full article

The variation of the classical viscous fingering instability is studied numerically in this work. An investigation of the viscous fingering phenomenon of immiscible displacement in the Hele–Shaw cell (HSC), where the displaced fluid is a shear-thinning fluid, was carried out numerically using the volume of fluid (VOF) method by adding a minor depth gradient or altering the geometry of the top plate in the HSC. The findings demonstrate how the presence of depth gradients can change the stability of the interface and offer a chance to regulate and adapt the fingering instability in response to the viscous fingering properties of air driving non-Newtonian fluids under various depth gradients. The relative breadth will shrink under the influence of the depth gradient, and the negative consequences of the gradient will be increasingly noticeable. Specifically, under different power-law indices, we found that with the enhancement of shear-thinning characteristics (lower power-law exponent n) in both positive and negative depth gradients, the fingers that protrude from the viscous fingers become shorter and thicker, resulting in higher displacement efficiency. Additionally, several modifications were performed to the upper plate’s design, and the findings revealed that the shape had no effect on the viscous fingering and only had an impact on the longitudinal amplitude. Based on the aforementioned traits, we may alter the HSC’s form or depth gradient to provide high-quality and effective work. Full article

Gas injection structures were designed for a vertical oven to improve the gas–solid flow countercurrent structure. This work measured the wall temperature distribution of the vertical oven to reflect gas velocity distribution, and simulated the basic gas–solid flow field. The effects of the number of gas orifice layers and the injection angle on the gas velocity distribution were examined. The results showed that number of gas injection layers had a significant effect on the gas velocity distribution in the lower zone. Compared with the distributions with one or three injection layers, two injection layers produce more uniform gas flow. A small particle size of 6–15 mm increased the bed resistance and solid fraction standard deviation. A nozzle angle of 45° was conducive to increase the gas velocity in the upper zone and forming a more uniform gas distribution. Full article