Search results

This study aims to develop a sol-gel-based coating to provide a long-lasting corrosion protection on AZ31 Mg alloy. Silane-based sol-gel coatings have been successfully applied to Mg alloys for corrosion protection. However, the micro or nano defects formed during condensation and solidification will cause the coating failure during a long-lasting immersion in a saline solution. More durable corrosion-protective sol-gel coatings are needed.

A sol-gel-based coating was modified on AZ31 Mg alloy by levodopa (DOPA). The long-lasting corrosion protection mechanism was studied by multiple electrochemical testing methods and surface characterization techniques.

Long-term testing by electrochemical impedance spectroscopy in aqueous 0.1 M NaCl indicated that the modified DOPA@sol-gel coating exhibited significant corrosion protection performance (>14 days). In comparison, the DOPA-free sol-gel coating failed only after three days of testing. The improved corrosion protection is attributed to the self-polymerized DOPA filling to the micro or nano defects in the glassy cross-linked networks of the sol-gel coating, which greatly improves the compactness of the coating.

The method of this study is simple and easy to process, the raw materials are green and the protective effect is excellent, which is of significance for the study of magnesium alloy corrosion protection.

A sol-gel process has been successfully utilized to form hybrid materials of poly(vinyl butyral) (PVB) and zirconium dioxide (zirconia). The gelation occurred due to the interaction between remaining hydroxyl group of PVB and zirconia. The hybrids showed good optical transparency and significant improvement in Young's modulus, dynamic mechanical property, abrasion resistance and impact resistance. The glass transition temperature of PVB shifted to higher temperatures by hybridization of PVB and zirconia.

The purpose of this paper is to develop a corrosion resistant zinc‐free coating for interstitial free steel.

The objective was achieved by developing a titania‐silica hybrid coating through a sol‐gel process by incorporating a dye molecule. The role of dye molecules was particularly important for enhancing the anti‐corrosion properties of the coating. The approach of current research was to develop a low‐temperature coating process that can bring similar performance to that obtained in case of zinc coating. Titania and silica precursors were mixed by stirring under a nitrogen atmosphere at 80°C to formulate a low‐temperature coating. The dye molecules were added before addition of water for subsequent hydrolysis. This complete formulation was applied over steel sheets using a roll coater as the application method.

The ranking order of improved corrosion resistance was found to be PATMS>EETMS>GPTMS and the addition of trace amount of tartrazine dye (60‐65 mg/l of liquid) in PATMS increased the corrosion service life in saline environments from 168 to 216 h, thus showing a promising improvement. Scanning Kelvin Probe results indicated that the corrosion reaction is controlled cathodically in presence of dye and, electrochemical impedance spectroscopy results exhibited a charge transfer resistance (Ct) of coating with dye of 419Ω cm², which was higher than that of a similar coating without dye (360Ω cm²), indicating increased corrosion protection.

This coating had improved barrier protection but lacked cut edge protection. Future work will focus on adding sacrificial protection by introducing compatible corrosion inhibitors, especially dye molecules, which are photosensitive.

This coating has huge potential for use in the automotive sector, especially for certain automotive parts (i.e. helm flanges), which suffer from poor durability in salty and high‐humidity atmospheres.

Since this coating formulation utilises a partially aqueous base, some environmental impact cannot be avoided, but it will have less impact than a complete solvent base formulation.

The novelty of the work was the introduction of dye molecules as the corrosion inhibitor and their compatibility in the hybrid coating system.

Examines the fourteenth published year of the ITCRR. Runs the whole gamut of textile innovation, research and testing, some of which investigates hitherto untouched aspects. Subjects discussed include cotton fabric processing, asbestos substitutes, textile adjuncts to cardiovascular surgery, wet textile processes, hand evaluation, nanotechnology, thermoplastic composites, robotic ironing, protective clothing (agricultural and industrial), ecological aspects of fibre properties – to name but a few! There would appear to be no limit to the future potential for textile applications.

The purpose of this paper is to synthesize and characterize nano-ceramic blue pigment Co_0.5Zn_0.5Al₂O₄ via polyacrylamide gel method. Generally, the high cost and the environmental toxicity of cobalt aluminate pigments lead them to become less common and cause problems in production process. To significantly reduce this problem, it is required to reduce the cobalt in the pigment and replace the cobalt with some amounts of zinc in the structure.

In this paper, calcination temperature and its effects on phase specification and color properties of final product were investigated. The powders were studied by using XRD, FESEM, TG/DTA, FTIR, UV-Vis and colorimetric in CIELab space, in which the calcination temperatures were set to 600°C, 800°C and 1,000 °C, and the inert atmosphere was air.

According to the XRD patterns, single-phase spinel structure with a good crystallinity was formed even in the low temperature. The infrared spectra displayed vibrations at about 500, 560 and 680 cm⁻¹, which were ascribed to the spinel structure. FESEM images showed nanoscale particles with an average size of 32 nm. Regarding the Co²⁺ spin transitions in tetrahedral sites, the UV-Vis spectra presented three bands at 552, 598 and 628 nm.

The colorimetric data indicated the formation of blue pigments corresponding to negative values of b*. The color of pigments was affected by calcination temperature.

The characterization analysis shows that a blue pigment has been obtained in this research. Different degrees of blue color were obtained at different calcination temperatures.

The purpose of this paper was to study the corrosion resistance of water-based sol-gel coatings containing titania nanoparticles doped with organic inhibitors for corrosion protection of AA2024 alloy.

The coatings were obtained using tetraethylorthosilicate, 3-glycidoxypropyltrimethoxysilane, titanium (IV) tetrapropoxide and poly(ethylene imine) polymer as cross-linking agents. As corrosions inhibitors, 2-mercaptobenzoxazole and salicylaldoxime were incorporated into the sol-gel for the improvement of the corrosion resistance. The corrosion protection performance of coatings was studied using the potentiodynamic scan and the electrochemical impedance spectroscopy (EIS) methods. Atomic force microscopy was used to investigate surface morphology of the coatings.

The results indicated that doping the sol-gel coatings with inhibitors leads to improvement of the corrosion protection. The comparison of doped coatings confirmed that corrosion protection performance of the sol-gel coatings doped with 2-mercaptobenzoxazole was better than for the sol-gel coatings doped with salicylaldoxime. Also the EIS results verified self-healing effects for the sol-gel coatings doped with 2-mercaptobenzoxazole.

This paper indicates 2-mercaptobenzoxazole and salicylaldoxime can be added as corrosion inhibitors to sol-gel coatings to improve their corrosion protective properties for AA2024 alloy.

This paper aims to improve the anti-corrosive properties of aluminum alloy AA2024-T3 by coating of hybrid sol-gel coating incorporated with TiO₂ nanosheets and to investigate the effect of nanosheets’ size on the improvement of corrosion-resistant performance.

A series of hybrid sol-gel films incorporated with varying amounts of TiO2 nanosheets were developed to enhance the corrosion protection performance of the bare metal. Scanning electron microscopy, transmission electron microscopy and atomic force microscopy were used to investigate the structure and morphology of the coatings obtained. In addition, the corrosion-resistant properties of the coatings were evaluated using salt spray test and electrochemical impedance spectroscopy.

The corrosion current was as low as 9.55 × 10-4 µA/cm² and optimal positive corrosion potential reached −0.6 V when the size and loading amount of TiO₂ nanosheet were optimized, resulting in a remarkable improvement in anti-corrosive properties.

This work first investigates the effect of incorporation of TiO₂ nanoparticles on hybrid sol-gel coating on the improvement of anti-corrosive performance of aluminum alloy AA2024-T3.

Uniform nanostructured TiO₂ thin film has been applied as an over coat on micro‐arc oxidized substrate, using the sol‐gel method. The anticorrosion performance of the coating have been evaluated using electrochemical techniques. Owing to increasing application of light alloys in industry, the purpose of this paper is to report effort to increase the corrosion and wear resistance properties of these alloys by applying a TiO₂ nanostructured coating using the sol‐gel method on the micro‐arc oxidation (MAO) surface. This approach will decrease the time for the MAO process, especially for achieving good mechanical properties, and will minimize energy consumption as well as achieving better results from the obtained coatings.

Sol‐gel coatings were deposited (on titanium substrates) by spin coating techniques. The morphologies and nanostructures of thin films were analyzed using scanning electron microscope, atomic force microscopy and grazing incidence X‐ray diffraction (XRD). The anticorrosion performance of the coating has been evaluated by using electrochemical techniques. Tafel polarization measurements provide an explanation for the increased resistance of nanostructured TiO₂ coated specimen against corrosion. Effective sol‐gel coating parameters were optimized with respect to this enhancement. Electrochemical impedance spectroscopy measurements showed the role of barrier layer on corrosion resistance of MAO and nanostructured TiO₂ coating.

The results showed that i_corr is decreased from 0.258 to 0.169 (μA/cm²). An optimized TiO₂ nanostructured coating with thickness of 74 nm will shift the open circuit potential (OCP) about 165 mV and will improve the corrosion prevention properties of coated samples. Corrosion resistance by these duplex coatings can be improved by a factor of more than three times, compared to that of the uncoated substrate. Increasing the coating thickness to more than 74 nm will decrease the physical and corrosion properties of coated samples. It can be concluded that samples with the optimized coating showed higher values of charge transfer resistance, due to the presence of a newly formed layer that accounted for the greater corrosion protection.

The results obtained in this research into nanostructured coating can be used wherever good corrosion and wear resistances are required.

The speed of treatment by this technique makes this method very suitable for industrial surface treatment of different components.

It is essentially valuable to use simpler methods for making the protected pigment by inclusion of hematite in a transparent zirconium silicate crystal. The purpose of this paper is to compare solution combustion and co‐precipitation methods as two different routes for synthesis of zircon‐based coral pigment.

X‐ray diffraction, scanning electron microscopy and simultaneous thermal analysis were used to characterise and evaluate the precipitated zircon and Fe₂O₃ phases. The synthesised samples were incorporated into a suitable ceramic glaze and then their L*, a* and b* colour parameters were measured via Commission Internationale de I'Eclairage colorimetric method.

The results revealed that partial reduction of hematite (α‐Fe₂O₃) to maghemite (γ‐Fe₂O₃) destroyed the quality of the pigment obtained from the combustion processing method. Nevertheless, it is found that co‐precipitation would be an appropriate method for synthesis coral pigment.

It is found that the solution combustion method is not able to directly synthesise a zircon‐based coral pigment during combustion reaction. Furthermore, the presence of carbon has led to partial reduction of hematite resulting in unwanted crystalline maghemite phase. This reveals that solution combustion method is not suitable to obtain zircon‐based coral pigment.

The conventional method to synthesise ceramic pigments is a solid‐state reaction that requires high temperature and long processing time. The products are usually coarse and inhomogeneous so this method requires further processing like wet or dry milling in order to produce fine powders. Diffusion barrier in solid‐state processing prevents the control of the microstructure and the reactivity of the system. Soft‐chemical routes such as solution combustion and co‐precipitation methods are better choices to get finer powders and to achieve the desired phases at lower temperatures in shorter time as well.

Co‐precipitation synthesis of iron‐zircon coral pigment using sodium silicate (water glass) as Si source and its comparison with solution combustion method is valuable and has not been reported until now.

Traditional analytical methods are often time-consuming and require bulky instruments, making their widespread implementation challenging. This paper aims to represent the principal concepts of biosensors as an introduction of this technology to readers and offers a comprehensive understanding of its functions.

The authors provide descriptions of the components, characteristics and advantages of biosensors along with the immobilization methods, followed by a brief discussion.

A biosensor is an analytical device comprising a specific biomolecule and a transducer in conjunction with an output system. The biomolecule recognizes a specific target which leads to a change in physicochemical properties of a system. This biorecognition phenomenon is later converted into a detectable signal by the transducer. Biosensors can essentially serve as rapid and cost-effective devices with excellent sensitivity and specificity for critical purposes in innumerable fields, ranging from scientific research to day-to-day applications.

Here, the authors explain and discuss the approaches and challenges with the aim of leading to an interest in biosensor development and improving their applications.