Search results

The purpose of this paper is to introduce the theoretical basis of N-order spectral spreading-compressing (SSC) frequency shift interference algorithm and expand it to active cancellation. An active cancellation simulation and verification system based on N-order SSC algorithm is established and carried out; simultaneously, the absorbing material coating stealth simulation of two kinds of thickness is carried out to compare the stealth effect with active cancellation system.

The active cancellation method based on N-order SSC algorithm is proposed based on theoretical formula derivation; the active cancellation simulation and verification system is established in MATLAB/Simulink. The full-size model is built by CATIA and meshed by hypermesh. The omnidirectional radar cross section (RCS) is calculated in cadFEKO, and the results are analyzed in postFEKO.

The simulations are implemented on a stealth fighter, and results show that after active cancellation, the peak of spectrum analyzer has reduced in all azimuths, the omnidirectional RCS has also decreased and the detection probability of almost all azimuths has dropped under 50 per cent. The absorbing material coating stealth simulations of two kinds of thickness are carried out, and results show that the stealth effect of active cancellation is much better than absorbing material coating.

An active cancellation system based on SSC algorithm is proposed in this paper, and the effect of active cancellation is verified and compared with that of absorbing materials. A new method for the current active stealth is provided in this paper.

Active cancellation simulation and verification system is established. RCS calculation module, signal-to-noise-ratio (SNR) calculation module and detection probability module are built to verify the effect of active cancellation system. Simultaneously, the absorbing material coating stealth simulation is carried out, and the stealth effect of absorbing material coating and active cancellation are compared and analyzed.

This review discusses the concept of edible nanocoatings (ENCs), the biomaterials used in the coating matrices, techniques of coating development, applications, challenges and safety regulations associated with nanotechnology in food products. These ENCs are capable of imparting increased shelf life, improved appearance, better physiological qualities and bioactive potentials such as antimicrobial and antioxidant properties. ENCs can be developed using the layer-by-layer method which forms multiple alternative layers adhered together primarily by electrostatic interactions.

Various keywords such as edible coatings (ECs), safety aspects and nanocoatings were used to search the literature from Google Scholar, Research Gate, ScienceDirect, Springer Link, Taylor and Francis and PubMed. After searching enough literature, 113 articles and research papers were examined, which provides the updated overview of different aspects of edible nano-coatings.

Consumers today are very much aware of the food quality and its safety. They demand food products with longer shelf life, which are minimally processed with natural or no preservatives. ECs based on biopolymers is an alternative technique, which is biodegradable and can be consumed as such without posing any safety risks. The emergence of nanotechnology in food processing has provided new insights to develop ECs at the nanoscale with improved mechanical and barrier properties

ECs are beneficial to consumers and to the environment. ECs have generated significant attention over years as an alternative to fossil-based plastics, considering their renewable and biodegradable features

Banana is an important tropical fruit with high demand in the market. The ripe fruits are less resistant to transport making logistics difficult. Moreover, as a climacteric fruit, it has a short post-harvest shelf life. Edible coatings/films, including active substances, have been used as an alternative for preserving fruits and vegetables during post-harvest period. The purpose of this study was to evaluate the incorporating clove essential oil on the properties of cassava starch films and their effect on the post-harvest quality of different banana varieties.

Cassava starch films incorporating clove essential oil were developed and the films were characterized with respect to moisture, thickness, solubility, water vapor permeability (WVP), biodegradability, color and in vitro antifungal activity. Cultivars such as Prata-Anã, Grand Nine, BRS Tropical and BRS Conquista were coated with cassava starch, cassava starch film with clove essential oil (CSEO) and polyvinyl polychloride (PVC). The quality of fruits was monitored during eight storage days using mass loss, total soluble solids content (TSS) and titratable acidity (TTA).

Incorporation of clove essential oil significantly increased film thickness, reduced moisture content, solubility and WVP (p < 0.05) and did not affect the biodegradability and color of the films. The essential oil incorporated films showed antifungal activity against the fungi Colletotrichum gloeosporioides and Colletotrichum musae, but not against the yeast Saccharomyces bourladii. CSEO and PVC coating were more efficient in reducing the mass loss, SS content and TTA of the coated fruits in all varieties studied. Both CSEO and PVC coatings improve the quality attributes such as TSS and TTA and reduced mass loss, of the banana varieties such as Prata-Anã, Grand Nine, BRS Tropical and BRS Conquista during storage.

The active film with essential oil showed antifungal activity and essential oil can be incorporated into other food systems. This study approaches a new possibility of film coating with essential oil for a banana that showed minimum weight loss and satisfactory quality and increased shelf life. This film coating demonstrates biodegradable characteristics that could be eco-friendly and sustainable to consumers.

The purpose of this study is to improve the anticorrosion performance of low nickel stainless steel (AISI 201) in 3.5% NaCl by electroactive polyimide/copper oxide (EPI/CuO) composites coating.

Electroactive polyimide/copper oxide (EPI/CuO) composites were prepared by oxidative coupling polymerization followed by thermal imidization method.

The functional and structural properties of composites were characterized by X-ray diffraction, Fourier transmission infra-red and ultra violet-visible spectroscopy and the surface topography was characterized by field emission scanning electron microscope analysis and anticorrosion performance in 3.5 Wt.% NaCl was evaluated by electrochemical techniques. The obtained results of electrochemical techniques measurement indicated that the composites coated samples give better corrosion protection against attacking electrolyte.

The ever-increasing price of nickel (Ni) is driving the industries to use low-Ni austenitic stainless steels (ASSs). However, it exhibits relatively poor corrosion resistance as compared with conventional Cr-Ni ASSs. Nonetheless, its corrosion resistance can be enhanced by polymeric (electroactive polyimide [EPI]) coating. CuO particles exhibit the hydrophobic properties and can be used as inorganic filler to incorporate in EPI to further enhance the corrosion protection. The present research paper is beneficial for industries to use low-cost AISI 201, enhance its corrosion resistance and replace the use of costly conventional Cr-Ni ASSs.

Magnesium-aluminum layered double hydroxides (LDH) with a platelet-like morphology were synthesized through a modified co-precipitation method. The purpose of this paper is to investigate calcined Mg-Al-CO₃ LDH (CLDH) as chloride ion traps.

The morphology and chemical composition of the synthesized materials were studied through UHR-SEM, EDS, FT-IR and XRD. The chloride ion adsorption was confirmed by XRD; the characteristic diffraction peaks of the reconstructed LDH structure were revealed, similar to the one before the thermal treatment process. The effect of varying the experimental conditions on the chloride ion adsorption, such as the initial target-ion concentration, the adsorbent material dosage, the solution temperature and the solution pH was also investigated.

The experimental data fitting revealed that the Langmuir equation is a better model on the basis of correlation coefficients (R²) and that the pseudo-second kinetic model can satisfactorily describe the chloride ion uptake.

The ability of Mg-Al CLDH to recover their layered structure upon exposure to aqueous sodium chloride solutions with concentrations up to 0.3 M (10,636 mg/L) through the chloride adsorption and the simultaneous rehydration process is clearly demonstrated.

Summary This paper describes an electrochemical procedure useful to the determination of metallic and oxidised parts in zinc‐base coatings obtained by thermal spraying. The procedure has been successfully applied to the examination of coatings made of pure zinc or of a zinc alloy containing 15% in weight of aluminium, as well as on corroded as on uncorroded samples. The method allows the degree of advancement of oxidation in the coating to be determined as a function of the exposure time; this permits an evaluation of the corrosion resistance to be made without having to wait for the appearance of rust on the protected steel plate. By this manner, the better resistance of the studied alloy compared to the pure zinc has been evidenced under severe conditions of attack by an aerated 5% NaCl solution. This could be attributed to a decrease in the oxidation rate of the metallic zinc in the alloy, owing to its higher aptitude to self‐sealing. The improved behaviour of the alloy has been attributed to the existence through the whole thickness of the coating of a coherent network made of an α‐aluminium‐rich phase, this explanation being in good agreement with the results of other investigations carried out by SEM + EDAX or by X‐Rays diffraction techniques, which have been reported elsewhere. Each studied coating was obtained from wires produced by Vieille‐Montagne under the trade‐names Zinacor 100 (pure electrolytic zinc) and Zinacor 850 (zinc‐base alloy containing 15% aluminium).

This paper aims to enhance the barrier properties and active protection of a water-based silane coating on mild steel through nanoclay and zinc acetylacetonate simultaneously included into the formulation.

The corrosion protection performance of the silane sol-gel coatings with no additive, zinc acetylacetonate, nanoclay and nanoclay + zinc acetylacetonate was monitored using electrochemical impedance spectroscopy during 5 h of immersion in a sodium chloride solution. Moreover, the surface of coatings was analyzed using a field emission scanning electron microscopy equipped with an energy dispersive X-ray spectrometer (FESEM-EDX) and water contact angle measurements.

In electrochemical impedance spectroscopy analysis, the impedance at low frequencies, coating resistance and charge transfer resistance were the parameters considered which indicated the superiority of silane coating formulated with both nanoclay and zinc acetylacetonate. According to the results of FESEM/EDX and water contact angle measurements, the superiority was linked with the enhancement in the barrier properties in the presence of nanoclay, as well as function of the corrosion inhibitor at coating–substrate interface.

According to the literature, there is no research conducted to study the impact of the simultaneous use of nanoclay and zinc acetylacetonate on the barrier properties and active protection of an eco-friendly silane sol-gel coating including glycidyloxypropyltrimethoxysilane, tetraethoxysilane and methyltriethoxysilane on mild steel in a sodium chloride solution.

This paper aims to focus on the research progress of intelligent self-healing anti-corrosion coatings in the aviation field in the past few years. The paper provides certain literature review supports and development direction suggestions for future research on intelligent self-healing coatings in aviation.

This mini-review uses a systematic literature review process to provide a comprehensive and up-to-date review of intelligent self-healing anti-corrosion coatings that have been researched and applied in the field of aviation in recent years. In total, 64 articles published in journals in this field in the last few years were analysed in this paper.

The authors conclude that the incorporation of multiple external stimulus-response mechanisms makes the coatings smarter in addition to their original self-healing corrosion protection function. In the future, further research is still needed in the research and development of new coating materials, the synergistic release of multiple self-healing mechanisms, coating preparation technology and corrosion monitoring technology.

To the best of the authors’ knowledge, this is one of the few systematic literature reviews on intelligent self-healing anti-corrosion coatings in aviation. The authors provide a comprehensive overview of the topical issues of such coatings and present their views and opinions by discussing the opportunities and challenges that self-healing coatings will face in future development.

The purpose of this paper is to present an overview of functional properties of the polysaccharide-based component and their application in developing edible film and coating for the food processing sector.

In this review study, approximately 271 research and review articles focusing on studies related to polysaccharide-based components and their film-forming properties. This article also focused on the application of polysaccharide-based edible film in the food sector.

From the literature reviewed, polysaccharide components and components-based edible film/coating is the biodegradable and eco-friendly packaging of the materials and directly consumed by the consumer with food. It has been reported that the polysaccharide components have excellent properties such as being nontoxic, antioxidant, antimicrobial, antifungal and with good nutrients. The polysaccharide-based edible film has lipid and gas barrier properties with excellent transparency and mechanical strength. In various studies, researchers worked on the development of polysaccharide-based edible film and coating by incorporating plant based natural antioxidants. This was primarily done for obtaining improved physical and chemical properties of the edible film and coating. In future, the technology of developing polysaccharide-based edible film and coating could be used for extending the shelf life and preserving the quality of fruits and vegetables at a commercial level. There is more need to understand the role of edible packaging and sustainability in the food and environment sector.

Through this review paper, possible applications of polysaccharide-based components and their function property in the formation of the edible film and their effect on fruits, vegetables and other food products are discussed after detailed studies of literature from thesis and journal article.

Demands for coatings with superior technical characteristics have induced the use of composite coatings, which usually represent an extremely strong product. The resin blend technique is a simple and useful method for improving paint properties. Coal tar resins are the most economical coating extensively used in the industry; short oil‐length alkyd resins are usually used for air and force‐dry industrial coatings for metal surfaces. The purpose of this paper is to evaluate coating blends composed of these resins, in particular, the effects of short oil‐length alkyd additive on the properties of coal tar binder.

One way to achieve new types of binders is to make combinations of the existing ones, in an ideal case retaining the desirable properties of both. The alkyd has important properties over the original drying oil. To achieve the goal of improving coal tar resin properties, short oil‐length alkyd was blended with it. The prepared short oil‐length alkyd was characterised using IR and ¹HNMR spectroscopy. The mixing ratio of short oil‐length alkyd with coal tar was up to 25 per cent. The compatibility of coating blend was characterised by scanning electron microscope. The physical, mechanical and chemical properties of the coating blend in addition to the corrosion resistance were determined according to ASTM methods.

In spite of a large number of synthetic resins being available for use in paint formulations, the alkyd resins surpassed all of them in versatility and low cost. The blend of short oil‐length alkyd resin with coal tar has yielded better coating blend properties. The coating blend showed significant enhancement of physical, mechanical and chemical properties such as gloss, drying time, adhesion, scratch hardness, acid and solvent resistance because the coating blend combines the properties of thermosetting and thermoplastic resins.

Alkyd resins are the most extensively used synthetic polymers in the coating industry. Modification of coal tar blend based on other type of polyester resins could also be studied in order to assess the applicability of the coal tar blend system found for other applications.

These types of alkyd resins can be applied in other bitumen composites as additives and reinforce agent.

The paper shows how the low‐cost modified coal tar binder can be used for air and force‐dry industrial coatings for metal surfaces.