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This study focuses on the design, development, and validation of two coating systems for corrosion protection of hot dip galvanized steel substrates. The coatings consist of epoxy-based resin reinforced with core-shell microcapsules, either cerium oxide or cuprous oxide core and a polymeric shell doped with cerium ions. The effect of the modification of the epoxy resin with a liquid rubber polymer has also been studied. Corrosion studies via electrochemical impedance spectroscopy (EIS) revealed that the coatings have enhanced barrier properties. Moreover, EIS studies on coatings with artificial scribes, demonstrated an autonomous response to damage and a selfhealing effect. Heat-induced material re-flow has also been observed after exposure to temperature higher than the T g of the system, which offered an additional self-healing mechanism, partially inhibiting the underlying corrosion processes when the liquid rubber is present in the system.

Mild or low-carbon steel has an increasing utilization and is widely used for building construction, machinery parts, and pipelines, because it can be machined easily and has enhanced weldability as well as a low price. In any case, the corrosion resistance of mild steel under the conditions in industrial applications or in atmosphere is a thoughtful concern. This study inquires into the application of 2-mecraptobenzothiazole (MBT) and Na2HPO4 as corrosion inhibitors for the protection of API 5L X42 pipeline steel in 3.5 wt % NaCl as well as in water from the Athens city supply system. The electrochemical/morphological characterizations of the aforementioned mild steel proved that the corrosion protection mechanisms can be assigned to the protective layers created onto the metal surface because of the presence of the inhibitors, which prevent chloride’s penetration. The synergistic effect of the MBT and Na2HPO4 corrosion inhibition behavior, in a molar ratio of 1:1, revealed that the additives performed effectively with corrosion inhibition efficiency above 90%.

Carbon-based nanomaterials are promising reinforcing elements for the development of “smart” self-sensing cementitious composites due to their exceptional mechanical and electrical properties. Significant research efforts have been committed on the synthesis of cement-based composite materials reinforced with carbonaceous nanostructures, covering every aspect of the production process (type of nanomaterial, mixing process, electrode type, measurement methods etc.). In this study, the aim is to develop a well-defined repeatable procedure for the fabrication as well as the evaluation of pressure-sensitive properties of intrinsically self-sensing cementitious composites incorporating carbon- based nanomaterials. Highly functionalized multi-walled carbon nanotubes with increased dispersibility in polar media were used in the development of advanced reinforced mortar specimens which increased their mechanical properties and provided repeatable pressure-sensitive properties.

Purpose The purpose of this paper is to focus on the investigation of nanomechanical behavior of new types of metal alloys protective coatings. For this purpose, poly(n-butylacrylate) was synthesized via activators regenerated by electron transfer-atom transfer radical polymerization and mixed with epoxy resins, and microcomposites. Design/methodology/approach Multi-layered coatings were applied on hot dip galvanized steel via a baker film applicator. Every layer containing the aforementioned copolymer differs in the proportion of the epoxy resin resulting in the production of a coating with a gradient from hard to soft from the substrate to the top. Nanomechanical performance is accessed via nanoindentation, providing information for structural and mechanical integrity, adhesion and resistance to wear. Findings The results reveal that through trajection of hardness mapping, the resistance is divided in three regions, namely, the polymer (matrix), interface (region close to/between spheres-shells) and spheres-shell regions. Originality/value The structural analysis, adhesion and mechanical integrity of the coatings are clearly demonstrated.

This study demonstrates the synthesis and characterisation of core-shell particles for the removal of chlorides from water. The evaluation of their efficiency was conducted under a variety of experimental conditions. The core-shell particles consist of an organic template coated with Mg-Al-NO 3 layered double hydroxides (LDH). The characterisation of the LDH traps in terms of their morphology, structure and composition was accomplished with a variety of techniques such as SEM, energy dispersive X-ray analysis, Fourier transform infrared spectroscopy, X-ray diffraction, and thermogravimetric analysis. The LDH trap chloride adsorption loading was evaluated in respect of several parameters such as temperature, pH, contact time and dosage of traps. The experimental data fitting on kinetics models indicated that the adsorption's rate determining step was the chemisorption mechanism.

In this work, materials that as additives in cement promote self-sealing/healing properties by the gradual release of water they absorb were synthesized, characterized and evaluated. Specifically, hybrid SAPs that absorb high ammounts of water encapsulated with SiO2 that facilitates their incorporation in the matrix since it improves their chemical affinity were investigated. The structure and morphology of the fabricated SAPs were characterized analytically and confirmed the synthesis of P(MAA-co-EGDMA)@SiO2 nanocomposite. Its particle size is expected to reduce the size of the pores formed due to the absorbing/desorbing water process during the mixing and curing of cement. Moreover, the water absorbance of the above mentioned material as well as its ability to maintain its original structure during subsequent cycles of absorbing/desorbing water from different mediums and specifically from distilled water (DW) and cement slurry filtrate (CS) were evaluated. CS was chosen to mimic the cementitious environment considering the presence of various ions and its pH value (~ 12). The results revealed that the absorption ratio of P(MAA-co-EGDMA)@SiO2 in DW and CS was higher than 1500 wt.% its original dry weight, while SEM pictures proved that the hybrid SAPs maintained their structure after the water absorption tests.

Purpose 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. Design/methodology/approach 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. Findings 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. Originality/value 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.